Physical Review D

(Particles, Fields, Gravitation, and Cosmology - 1)

January 2007

Volume 75, Number 1 , Articles (01xxxx)

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Study of the charmed baryonic decays [overline B]⁰-->Sigma_c⁺⁺[overline p]pi^- and [overline B]⁰-->Sigma_c⁰[overline p]pi⁺

K. S. Park et al. (Belle Collaboration)

Published 8 January 2007 (6 pages)
011101(R) Full Text: PDF (2722 kB) | Buy Article

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We study the three-body charmed baryonic decays [overline B]⁰-->Sigmac⁺⁺[overline p]pi^- and [overline B]⁰-->Sigmac⁰[overline p]pi⁺ in the four-body final state [overline B]⁰-->Lambdac⁺[overline p]pi⁺pi^-, using a data sample of 357 fb^-1 accumulated at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e⁺e^- collider. We measure the branching fractions [script B]([overline B]⁰-->Sigmac(2455)⁺⁺[overline p]pi^-)=(2.1±0.2±0.3±0.5)×10^-4, [script B]([overline B]⁰-->Sigmac(2455)⁰[overline p]pi⁺)=(1.4±0.2±0.2±0.4)×10^-4 and [script B]([overline B]⁰-->Sigmac(2520)⁺⁺[overline p]pi^-)=(1.2±0.1±0.2±0.3)×10^-4 with signal significances of 13.1sigma, 9.4sigma and 7.1sigma, respectively. The errors are statistical, systematic, and due to the uncertainty in [script B](Lambdac⁺-->pK^-pi⁺), respectively. We also set an upper limit [script B]([overline B]⁰-->Sigmac(2520)⁰[overline p]pi⁺)<0.38×10^-4 at the 90% confidence level. In addition, we obtain a nonresonant branching fraction of (6.4±0.4±0.9±1.7)×10^-4, and a total branching fraction of (11.2±0.5±1.4±2.9)×10^-4 for [overline B]⁰-->Lambdac⁺[overline p]pi⁺pi^-.

Search for psi(2S)-->eta_cpi⁺pi^-pi⁰

T. K. Pedlar et al. (CLEO Collaboration)

Published 10 January 2007 (5 pages)
011102(R) Full Text: PDF (336 kB) | Buy Article

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Using 5.63 pb^-1 of data accumulated at the psi(2S) resonance with the CLEO III and CLEO-c detectors corresponding to 3.08×10⁶ psi(2S) decays, a search is performed for the decay psi(2S)-->etacpi⁺pi^-pi⁰ to test a theoretical prediction based upon the assumption that the c[overline c] pair in the psi(2S) does not annihilate directly into three gluons but rather survives before annihilating. No signal is observed, and a combined upper limit from six etac decay modes is determined to be [script B](psi(2S)-->etacpi⁺pi^-pi⁰)<=1.0×10^-3 at 90% C.L. This upper limit is about an order of magnitude below the theoretical expectation.

Beam-charge azimuthal asymmetry and deeply virtual Compton scattering

A. Airapetian et al. (HERMES Collaboration)

Published 26 January 2007 (5 pages)
011103(R) Full Text: PDF (205 kB) | Buy Article

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The first observation of an azimuthal cross section asymmetry with respect to the charge of the incoming lepton beam is reported from a study of hard exclusive electroproduction of real photons. The data have been accumulated by the HERMES experiment at DESY, in which the HERA 27.6 GeV electron or positron beam scattered off an unpolarized hydrogen gas target. The observed asymmetry is attributed to the interference between the Bethe-Heitler process and the deeply virtual Compton scattering (DVCS) process. The interference term is sensitive to DVCS amplitudes, which provide the most direct access to generalized parton distributions.

Higgs instability in gapless superfluidity/superconductivity

Ioannis Giannakis, Defu Hou, Mei Huang, and Hai-cang Ren

Published 19 January 2007 (5 pages)
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In this letter we explore the Higgs instability in the gapless superfluid/superconducting phase. This is in addition to the (chromo)magnetic instability that is related to the fluctuations of the Nambu-Goldstone bosonic fields. While the latter may induce a single-plane-wave Larkin-Ovchinnikov-Fulde-Ferrel state, the Higgs instability favors spatial inhomogeneity. In the case of the 2-flavor color superconductivity state the Higgs instability can only be partially removed by the electric Coulomb energy. But this does not exclude the possibility that it can be completely removed in other exotic states such as the gapless color-flavor locked state.

Accelerating staggered-fermion dynamics with the rational hybrid Monte Carlo algorithm

M. A. Clark and A. D. Kennedy

Published 24 January 2007 (5 pages)
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Improved staggered-fermion formulations are a popular choice for lattice QCD calculations. Historically, the algorithm used for such calculations has been the inexact R algorithm, which has systematic errors that only vanish as the square of the integration step size. We describe how the exact rational hybrid Monte Carlo (RHMC) algorithm may be used in this context, and show that for parameters corresponding to current state-of-the-art computations it leads to a factor of approximately seven decrease in cost as well as having no step-size errors.

Thermal leptogenesis in extended supersymmetric seesaw model

M. Hirsch, J. W. F. Valle, M. Malinský, J. C. Romão, and U. Sarkar

Published 29 January 2007 (4 pages)
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We consider an extended supersymmetric SO(10) seesaw model with only doublet Higgs scalars, in which neutrino masses are suppressed by the scale of D-parity violation. Leptogenesis can occur at the TeV scale through the decay of a singlet Sigma, thereby avoiding the gravitino crisis. Washout of the asymmetry can be effectively suppressed by the absence of direct couplings of Sigma to leptons.

Chiral transition and mesonic excitations for quarks with thermal masses

Yoshimasa Hidaka and Masakiyo Kitazawa

Published 5 January 2007 (5 pages)
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See Also: Erratum

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We study the effect of a thermal quark mass, mT, on the chiral phase transition and mesonic excitations in the light quark sector at finite temperature in a simple chirally symmetric model. We show that, while nonzero mT lowers the chiral condensate, the chiral transition remains of second order. It is argued that the mesonic excitations have a large decay rate at energies below 2mT, owing to the Landau damping of the quarks and the van Hove singularities of the collective modes.

ARTICLES

Search of neutrino magnetic moments with a high-purity germanium detector at the Kuo-Sheng nuclear power station

H. T. Wong et al. (TEXONO Collaboration)

Published 5 January 2007 (16 pages)
012001 Full Text: PDF (3729 kB) | Buy Article

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A search of neutrino magnetic moments was carried out at the Kuo-Sheng nuclear power station at a distance of 28 m from the 2.9 GW reactor core. With a high purity germanium detector of mass 1.06 kg surrounded by scintillating NaI(Tl) and CsI(Tl) crystals as anti-Compton detectors, a detection threshold of 5 keV and a background level of 1 kg^-1 keV^-1 day^-1 near threshold were achieved. Details of the reactor neutrino source, experimental hardware, background understanding, and analysis methods are presented. Based on 570.7 and 127.8 days of Reactor ON and OFF data, respectively, at an average Reactor ON electron antineutrino flux of 6.4×10¹² cm^-2 s^-1, the limit on the neutrino magnetic moments of µ[overline nu ][sub e]<7.4×10^-11µB at 90% confidence level was derived. Indirect bounds on the [overline nu ]e radiative decay lifetimes were inferred.

Measurement of [script B](Upsilon(5S)-->B_s^(*)[overline B]_s^(*)) using phi mesons

G. S. Huang et al. (CLEO Collaboration)

Published 9 January 2007 (13 pages)
012002 Full Text: PDF (1020 kB) | Buy Article

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Knowledge of the Bs decay fraction of the Upsilon(5S) resonance, fS, is important for Bs meson studies at the Upsilon(5S) energy. Using a data sample collected by the CLEO III detector at CESR consisting of 0.423 fb^-1 on the Upsilon(5S) resonance, 6.34 fb^-1 on the Upsilon(4S) and 2.32 fb^-1 in the continuum below the Upsilon(4S), we measure [script B](Upsilon(5S)-->phiX)=(13.8±0.7-1.5^+2.3)% and [script B](Upsilon(4S)-->phiX)=(7.1±0.1±0.6)%; the ratio of the two rates is (1.9±0.1-0.2^+0.3). This is the first measurement of the phi meson yield from the Upsilon(5S). Using these rates, and a model dependent estimate of [script B](Bs-->phiX), we determine fS=(24.6±2.9-5.3^+11.0)%. We also update our previous independent measurement of fS made using the inclusive Ds yields to now be (16.8±2.6-3.4^+6.7)%, due to a better estimate of the number of hadronic events. We also report the total Upsilon(5S) hadronic cross section above continuum to be sigma(e⁺e^--->Upsilon(5S))=(0.301±0.002±0.039) nb. This allows us to extract the fraction of B mesons as (58.9±10.0±9.2)%, equal to 1-fS. Averaging the three methods gives a model dependent result of fS=(21-3⁺⁶)%.

Inclusive Lambda_c⁺ production in e⁺e^- annihilations at sqrt(s)=10.54 GeV and in Upsilon(4S) decays

B. Aubert et al. (BABAR Collaboration)

Published 9 January 2007 (16 pages)
012003 Full Text: PDF (588 kB) | Buy Article

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We present measurements of the total production rates and momentum distributions of the charmed baryon Lambdac⁺ in e⁺e^--->hadrons at a center-of-mass energy of 10.54 GeV and in Upsilon(4S) decays. In hadronic events at 10.54 GeV, charmed hadrons are almost exclusively leading particles in e⁺e^--->c[overline c] events, allowing direct studies of c-quark fragmentation. We measure a momentum distribution for Lambdac⁺ baryons that differs significantly from those measured previously for charmed mesons. Comparing with a number of models, we find none that can describe the distribution completely. We measure an average scaled momentum of <xp>=0.574±0.009 and a total rate of N Lambda c^{q[overline q]}=0.057±0.002(exp.)±0.015(BF) Lambdac⁺ per hadronic event, where the experimental error is much smaller than that due to the branching fraction into the reconstructed decay mode, pK^-pi⁺. In Upsilon(4S) decays we measure a total rate of N Lambda c^Upsilon=0.091±0.006(exp.)±0.024(BF) per Upsilon(4S) decay, and find a much softer momentum distribution than expected from B decays into a Lambdac⁺ plus an antinucleon and one to three pions.

Measurement of the rare decay pi⁰-->e⁺e^-

E. Abouzaid et al.

Published 11 January 2007 (6 pages)
012004 Full Text: PDF (248 kB) | Buy Article

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The branching ratio of the rare decay pi⁰-->e⁺e^- has been measured precisely, using the complete data set from the KTeV E799-II experiment at Fermilab. We observe 794 candidate pi⁰-->e⁺e^- events using KL-->3pi⁰ as a source of tagged pi⁰s. The expected background is 52.7±11.2 events, predominantly from high e⁺e^- mass pi⁰-->e⁺e^-gamma decays. We have measured B(pi⁰-->e⁺e^-,(me⁺e^-/mpi⁰)²>0.95)=(6.44±0.25stat±0.22syst)×10^-8, which is above the unitary bound from pi⁰-->gammagamma and within the range of theoretical expectations from the standard model.

Xi⁰ and [overline Xi ]⁰ polarization measurements at 800 GeV/c

E. Abouzaid et al. (KTeV Collaboration)

Published 11 January 2007 (5 pages)
012005 Full Text: PDF (358 kB) | Buy Article

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The polarization of Xi⁰ and [overline Xi ]⁰ hyperons produced by 800 GeV/c protons on a BeO target at a fixed targeting angle of 4.8 mrad is measured by the KTeV experiment at Fermilab. Our result of 9.7% for Xi⁰ polarization shows no significant energy dependence when compared to a result obtained at 400 GeV/c production energy and at twice our targeting angle. The polarization of the [overline Xi ]⁰ is measured for the first time and found to be consistent with zero. We also examine the dependence of polarization on production pt.

Dalitz analysis of three-body charmless B⁰-->K⁰pi⁺pi^- decay

A. Garmash et al. (Belle Collaboration)

Published 12 January 2007 (10 pages)
012006 Full Text: PDF (946 kB) | Buy Article

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We report results of a Dalitz plot analysis of the three-body charmless B⁰-->K⁰pi⁺pi^- decay. The analysis is performed with a data sample that contains 388×10⁶ B[overline B] pairs collected near the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e⁺e^- collider. Measurements of branching fractions for the quasi-two-body decays B⁰-->rho(770)⁰K⁰, B⁰-->f0(980)K⁰, B⁰-->K^*(892)⁺pi^-, B⁰-->K^*(1430)⁺pi^-, and upper limits on several other quasi-two-body decay modes are reported.

Precise determination of the spin structure function g₁ of the proton, deuteron, and neutron

A. Airapetian et al. (HERMES Collaboration)

Published 16 January 2007 (48 pages)
012007 Full Text: PDF (1040 kB) | Buy Article

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Precise measurements of the spin structure functions of the proton g1^p(x,Q²) and deuteron g1^d(x,Q²) are presented over the kinematic range 0.0041<=x<=0.9 and 0.18 GeV²<=Q²<=20 GeV². The data were collected at the HERMES experiment at DESY, in deep-inelastic scattering of 27.6 GeV longitudinally polarized positrons off longitudinally polarized hydrogen and deuterium gas targets internal to the HERA storage ring. The neutron spin structure function g1ⁿ is extracted by combining proton and deuteron data. The integrals of g1^p,d at Q²=5 GeV² are evaluated over the measured x range. Neglecting any possible contribution to the g1^d integral from the region x<=0.021, a value of 0.330±0.011(theo)±0.025(exp)±0.028(evol) is obtained for the flavor-singlet axial charge a0 in a leading-twist next-to-next-to-leading-order analysis.

Improved measurements of the branching fractions for B⁰-->pi⁺pi^- and B⁰-->K⁺pi^-, and a search for B⁰-->K⁺K^-

B. Aubert et al. (BABAR Collaboration)

Published 23 January 2007 (9 pages)
012008 Full Text: PDF (324 kB) | Buy Article

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We present measurements of the branching fractions for the charmless two-body decays B⁰-->pi⁺pi^- and B⁰-->K⁺pi^-, and a search for the decay B⁰-->K⁺K^-. We include the effects of final-state radiation from the daughter mesons for the first time, and quote branching fractions for the inclusive processes B⁰-->h⁺h^[prime]-ngamma, where h and h^[prime] are pions or kaons. The maximum value of the sum of the energies of the n undetected photons, Egamma^max, is mode-dependent. Using a data sample of approximately 227×10⁶ Upsilon(4S)-->B[overline B] decays collected with the BABAR detector at the PEP-II asymmetric-energy e⁺e^- collider at SLAC, we measure: [script B](B⁰-->pi⁺pi^-ngamma;Egamma^max=150 MeV)=(5.1±0.4±0.2)×10^-6, [script B](B⁰-->K⁺pi^-ngamma;Egamma^max=105 MeV)=(18.1±0.6±0.6)×10^-6, [script B](B⁰-->K⁺K^-ngamma;Egamma^max=59 MeV)<0.5×10^-6(90% confidence level), where the first uncertainty is statistical and the second is systematic. Theoretical calculations can be used to extrapolate from the above measurements the nonradiative branching fractions, [script B]⁰. Using one such calculation, we find: [script B]⁰(B⁰-->pi⁺pi^-)=(5.5±0.4±0.3)×10^-6, [script B]⁰(B⁰-->K⁺pi^-)=(19.1±0.6±0.6)×10^-6, [script B]⁰(B⁰-->K⁺K^-)<0.5×10^-6(90% confidence level). Meaningful comparison between theory and experiment, as well as combination of measurements from different experiments, can be performed only in terms of these nonradiative quantities.

Antideuteron production in Upsilon(nS) decays and the nearby continuum

D. M. Asner et al. (CLEO Collaboration)

Published 24 January 2007 (9 pages)
012009 Full Text: PDF (465 kB) | Buy Article

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Using CLEO data, we study the production of the antideuteron, [overline d], in Upsilon(nS) resonance decays and the nearby continuum. The branching ratios obtained are [script B]^dir(Upsilon(1S)-->[overline d]X)=(3.36±0.23±0.25)×10^-5, [script B](Upsilon(1S)-->[overline d]X)=(2.86±0.19±0.21)×10^-5, and [script B](Upsilon(2S)-->[overline d]X)=(3.37±0.50±0.25)×10^-5, where the “dir” superscript indicates that decays produced via reannihilation of the b[overline b] pair to a gamma^* are removed from both the signal and the normalizing number of Upsilon(1S) decays in order to isolate direct decays of the Upsilon(1S) to ggg, gggamma. Upper limits at 90% C.L. are given for [script B](Upsilon(4S)-->[overline d]X)<1.3×10^-5, and continuum production sigma(e⁺e^--->[overline d]X)<0.031 pb. The Upsilon(2S) data is also used to extract a limit on chibJ-->[overline d]X. The results indicate enhanced deuteron production in ggg, gggamma hadronization compared to gamma^*-->q[overline q]. Baryon number compensation is also investigated with the large Upsilon(1S)-->[overline d]X sample.

Measurement of the B⁺ production cross section in p[overline p] collisions at sqrt(s)=1960 GeV

A. Abulencia et al. (CDF Collaboration)

Published 29 January 2007 (12 pages)
012010 Full Text: PDF (481 kB) | Buy Article

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We present a new measurement of the B⁺ meson differential cross section dsigma/dpT at sqrt(s)=1960 GeV. The data correspond to an integrated luminosity of 739 pb^-1 collected with the upgraded CDF detector (CDF II) at the Fermilab Tevatron collider. B⁺ candidates are reconstructed through the decay B⁺-->J/psiK⁺, with J/psi-->µ⁺µ^-. The integrated cross section for producing B⁺ mesons with pT>=6 GeV/c and |y|<=1 is measured to be 2.78±0.24 µb.

Scalar mesons in radiative phi-->K⁰[overline K]⁰gamma decay

A. Gokalp, C. S. Korkmaz, and O. Yilmaz

Published 3 January 2007 (5 pages)
013001 Full Text: PDF (214 kB) | Buy Article

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We study the radiative phi-->K⁰[overline K]⁰gamma decay within a phenomenological framework by considering the contributions of the f0(980) and a0(980) scalar resonances. We calculate the branching ratio B(phi-->K⁰[overline K]⁰gamma) by employing the coupling constants gf0K⁺K^- and ga0K⁺K^- as determined by different experimental groups.

Precise mass-dependent QED contributions to leptonic g-2 at order alpha² and alpha³

M. Passera

Published 4 January 2007 (6 pages)
013002 Full Text: PDF (147 kB) | Buy Article

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Improved values for the two- and three-loop mass-dependent QED contributions to the anomalous magnetic moments of the electron, muon, and tau lepton are presented. The standard model prediction for the electron (g-2) is compared with its most precise recent measurement, providing a value of the fine-structure constant in agreement with a recently published determination. For the tau lepton, differences with previously published results are found and discussed.

Neutrino phenomenology of very low-energy seesaw scenarios

André de Gouvêa, James Jenkins, and Nirmala Vasudevan

Published 9 January 2007 (14 pages)
013003 Full Text: PDF (564 kB) | Buy Article

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The standard model augmented by the presence of gauge-singlet right-handed neutrinos proves to be an ideal scenario for accommodating nonzero neutrino masses. Among the new parameters of this “new standard model” are right-handed neutrino Majorana masses M. Theoretical prejudice points to M much larger than the electroweak symmetry breaking scale, but it has recently been emphasized that all M values are technically natural and should be explored. Indeed, M around 1–10 eV can accommodate an elegant oscillation solution to the liquid scintillator neutrino detector (LSND) anomaly, while other M values lead to several observable consequences. We consider the phenomenology of low-energy (M<~1 keV) seesaw scenarios. By exploring such a framework with three right-handed neutrinos, we can consistently fit all oscillation data—including those from LSND—while partially addressing several astrophysical puzzles, including anomalous pulsar kicks, heavy element nucleosynthesis in supernovae, and the existence of warm dark matter. In order to accomplish all of this, we find that a nonstandard cosmological scenario is required. Finally, low-energy seesaws—regardless of their relation to the LSND anomaly—can also be tested by future tritium beta-decay experiments, neutrinoless double-beta decay searches, and other observables. We estimate the sensitivity of such probes to M.

Need for purely laboratory-based axionlike particle searches

Joerg Jaeckel, Eduard Massó, Javier Redondo, Andreas Ringwald, and Fuminobu Takahashi

Published 9 January 2007 (9 pages)
013004 Full Text: PDF (309 kB) | Buy Article

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The PVLAS signal has led to the proposal of many experiments searching for light bosons coupled to photons. The coupling strength probed by these near-future searches is, however, far from the allowed region, if astrophysical bounds apply. But the environmental conditions for the production of axionlike particles in stars are very different from those present in laboratories. We consider the case in which the coupling and the mass of an axionlike particle depend on environmental conditions such as the temperature and matter density. This can relax astrophysical bounds by several orders of magnitude, just enough to allow for the PVLAS signal. This creates exciting possibilities for a detection in near-future experiments.

Weak boson emission in hadron collider processes

U. Baur

Published 11 January 2007 (21 pages)
013005 Full Text: PDF (907 kB) | Buy Article

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The [script O](alpha) virtual weak radiative corrections to many hadron collider processes are known to become large and negative at high energies, due to the appearance of Sudakov-like logarithms. At the same order in perturbation theory, weak boson emission diagrams contribute. Since the W and Z bosons are massive, the [script O](alpha) virtual weak radiative corrections and the contributions from weak boson emission are separately finite. Thus, unlike in QED or QCD calculations, there is no technical reason for including gauge boson emission diagrams in calculations of electroweak radiative corrections. In most calculations of the [script O](alpha) electroweak radiative corrections, weak boson emission diagrams are therefore not taken into account. Another reason for not including these diagrams is that they lead to final states which differ from that of the original process. However, in experiment, one usually considers partially inclusive final states. Weak boson emission diagrams thus should be included in calculations of electroweak radiative corrections. In this paper, I examine the role of weak boson emission in those processes at the Fermilab Tevatron and the CERN LHC for which the one-loop electroweak radiative corrections are known to become large at high energies (inclusive jet, isolated photon, Z+1 jet, Drell-Yan, di-boson, [overline t]t, and single top production). In general, I find that the cross section for weak boson emission is substantial at high energies and that weak boson emission and the [script O](alpha) virtual weak radiative corrections partially cancel.

Resolving the eightfold neutrino parameter degeneracy by two identical detectors with different baselines

Takaaki Kajita, Hisakazu Minakata, Shoei Nakayama, and Hiroshi Nunokawa

Published 19 January 2007 (12 pages)
013006 Full Text: PDF (477 kB) | Buy Article

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We have shown in a previous paper that two identical detectors with each fiducial mass of 0.27 megaton water, one in Kamioka and the other in Korea, which receive the (anti-) muon neutrino beam of 4 MW power from J-PARC facility have potential of determining the neutrino mass hierarchy and discovering CP violation by resolving the degeneracies associated with them. In this paper, we point out that the same setting has capability of resolving the theta23 octant degeneracy in region where sin²2theta23<~0.97 at 2 standard deviation confidence level even for very small values of theta13. Altogether, it is demonstrated that one can solve all the eightfold neutrino parameter degeneracies in situ by using the Tokai-to-Kamioka-Korea setting if theta13 is within reach by the next generation superbeam experiments. We also prove the property called “decoupling between the degeneracies”, which is valid to first-order in perturbation theory of the earth matter effect, that guarantees approximate independence between analyses to solve any one of the three different type of degeneracies.

QCD corrections to Higgs pair production in bottom quark fusion

Sally Dawson, Chung Kao, Yili Wang, and Peter Williams

Published 22 January 2007 (12 pages)
013007 Full Text: PDF (640 kB) | Buy Article

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We present a complete next-to-leading-order (NLO) calculation for the total cross section of inclusive Higgs pair production via bottom-quark fusion (b[overline b]-->hh) at the CERN Large Hadron Collider (LHC) in the standard model. The NLO QCD corrections lead to less dependence on the renormalization scale (µR) and the factorization scale (µF) than the leading-order (LO) cross section, and they significantly increase the LO cross section. The rate for inclusive Higgs pair production is small in the standard model, but can be large in models with enhanced couplings of the b quark to the Higgs bosons.

Extracting |V_ub| from B-->pilnu decays using a multiply-subtracted Omnès dispersion relation

Jonathan M Flynn and Juan Nieves

Published 22 January 2007 (6 pages)
013008 Full Text: PDF (205 kB) | Buy Article

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We use a multiply-subtracted Omnès dispersion relation for the form factor f⁺ in B-->pi semileptonic decay, allowing the direct input of experimental and theoretical information to constrain its dependence on q², thereby improving the precision of the extracted value of |Vub|. Apart from these inputs we use only unitarity and analyticity properties. We obtain |Vub|=(4.02±0.35)×10^-3, improving the agreement with the value determined from inclusive methods, and competitive in precision with them.

Mass splittings in Sigma_b and Sigma_b^*

Jonathan L. Rosner

Published 25 January 2007 (3 pages)
013009 Full Text: PDF (107 kB) | Buy Article

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The charged Sigmab and Sigmab^* states have recently been reported by the CDF Collaboration. The relation of their reported charge-averaged masses to expectations based on the quark model is reviewed briefly. A relation is proved among the DeltaI=1 electromagnetic mass differences Sigma1[equivalent]M(Sigma⁺)-M(Sigma^-), Sigma1^*[equivalent]M(Sigma^*+)-M(Sigma^*-), Sigmab1[equivalent]M(Sigmab⁺)-M(Sigmab^-), and Sigmab1^*[equivalent]M(Sigmab^*+)-M(Sigmab^*-). The relation is Sigmab1^*-Sigmab1=(ms/mb)(Sigma1^*-Sigma1), leading to the expectation Sigmab1^*-Sigmab1=0.40±0.07 MeV.

Periodogram and likelihood periodicity search in the SNO solar neutrino data

Gioacchino Ranucci and Marco Rovere

Published 25 January 2007 (14 pages)
013010 Full Text: PDF (1966 kB) | Buy Article

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In this work a detailed spectral analysis for the periodicity search of the time series of the ⁸B solar neutrino flux released by the SNO Collaboration is presented. The data have been publicly released with truncation of the event times to the unit of day (1 day binning); they are thus suited to undergo the traditional Lomb-Scargle analysis for periodicity investigation, as well as an extension of such a method based on a likelihood approach. The results of the analysis presented here confirm the absence of modulation signatures in the SNO data. For completeness, a more refined “1 day binned” likelihood is also illustrated, which approximates the unbinned likelihood methodology, based upon the availability of the full time information, adopted by the SNO collaboration. Finally, this work is completed with two different joint analyses of the SNO and Super-Kamiokande data, respectively, over the common and the entire data taking periods. While both analyses reinforce the case of the constancy of the neutrino flux, the latter in addition provides evidence of the detection at the 99.7% confidence level of the annual modulation spectral line due to the Earth's orbit eccentricity around the Sun.

Leptonic CP violation studies at MiniBooNE in the (3+2) sterile neutrino oscillation hypothesis

G. Karagiorgi, A. Aguilar-Arevalo, J. M. Conrad, M. H. Shaevitz, K. Whisnant, M. Sorel, and V. Barger

Published 29 January 2007 (8 pages)
013011 Full Text: PDF (556 kB) | Buy Article

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We investigate the extent to which leptonic CP-violation in (3+2) sterile neutrino models leads to different oscillation probabilities for [overline nu ]µ-->[overline nu ]e and nuµ-->nue oscillations at MiniBooNE. We are using a combined analysis of short-baseline (SBL) oscillation results, including the LSND and null SBL results, to which we impose additional constraints from atmospheric oscillation data. We obtain the favored regions in MiniBooNE oscillation probability space for both (3+2) CP-conserving and (3+2) CP-violating models. We further investigate the allowed CP-violation phase values and the MiniBooNE reach for such a CP violation measurement. The analysis shows that the oscillation probabilities in MiniBooNE neutrino and antineutrino running modes can differ significantly, with the latter possibly being as much as 3 times larger than the first. In addition, we also show that all possible values of the single CP-violation phase measurable at short baselines in (3+2) models are allowed within 99% CL by existing data.

µ-tau symmetry and radiatively generated leptogenesis

Y. H. Ahn, Sin Kyu Kang, C. S. Kim, and Jake Lee

Published 30 January 2007 (8 pages)
013012 Full Text: PDF (321 kB) | Buy Article

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We consider a µ-tau symmetry in neutrino sectors realized at the GUT scale in the context of a seesaw model. In our scenario, the exact µ-tau symmetry realized in the basis where the charged lepton and heavy Majorana neutrino mass matrices are diagonal leads to vanishing lepton asymmetries. We find that, in the minimal supersymmetric extension of the seesaw model with large tanbeta, the renormalization group (RG) evolution from the GUT scale to seesaw scale can induce a successful leptogenesis even without introducing any symmetry breaking terms by hand, whereas such RG effects lead to tiny deviations of theta23 and theta13 from pi/4 and zero, respectively. It is shown that the right amount of the baryon asymmetry etaB can be achieved via so-called resonant leptogenesis, which can be realized at rather low seesaw scale with large tanbeta in our scenario so that the well-known gravitino problem is safely avoided.

Lepton flavor violation and supersymmetric Dirac leptogenesis

Brooks Thomas and Manuel Toharia

Published 31 January 2007 (9 pages)
013013 Full Text: PDF (311 kB) | Buy Article

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Dirac leptogenesis (or Dirac neutrinogenesis), in which neutrinos are purely Dirac particles, is an interesting alternative to the standard leptogenesis scenario. In its supersymmetric version, the modified form of the superpotential required for successful baryogenesis contributes new, generically nonflavor-diagonal terms to the slepton and sneutrino mass matrices. In this work, we examine how current experimental bounds on flavor-changing effects in the lepton sector (and particularly the bound on µ-->egamma) constrain Dirac leptogenesis and we find that it is capable of succeeding with superpartner masses as low as ~100 GeV. For such light scalars and electroweakinos, upcoming experiments such as MEG are generically expected to observe signals of lepton flavor violation.

Quark contribution to the small-x evolution of color dipole

Ian Balitsky

Published 2 January 2007 (21 pages)
014001 Full Text: PDF (593 kB) | Buy Article

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The small-x deep inelastic scattering in the saturation region is governed by the nonlinear evolution of Wilson-lines operators. In the leading logarithmic approximation it is given by the Balitsky-Kovchegov (BK) equation for the evolution of color dipoles. In the next-to-leading order (NLO) the nonlinear equation gets contributions from quark and gluon loops. In this paper I calculate the quark-loop contribution to small-x evolution of Wilson lines in the NLO. It turns out that there are no new operators at the one-loop level—just as at the tree level, the high-energy scattering can be described in terms of Wilson lines. In addition, from the analysis of quark loops I find that the argument of coupling constant in the BK equation is determined by the size of the parent dipole rather than by the size of produced dipoles. These results are to be supported by future calculation of gluon loops.

Improved method for CKM constraints in charmless three-body B and B_s decays

Michael Gronau, Dan Pirjol, Amarjit Soni, and Jure Zupan

Published 2 January 2007 (11 pages)
014002 Full Text: PDF (390 kB) | Buy Article

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Recently Ciuchini, Pierini, and Silvestrini proposed a method for constraining CKM parameters in B-->Kpipi and Bs-->Kpipi through phase measurements of amplitudes involving I=3/2 K^*pi final states. We show that complementary information on CKM parameters may be obtained by studying the phases of DeltaI=1 B-->(K^*pi)I=1/2, Bs-->(K^*[overline K])I=1 and Bs-->([overline K]^*K)I=1 amplitudes. Hadronic uncertainties in these constraints from electroweak penguin operators O9 and O10, studied using flavor SU(3), are shown to be very small in B-->Kpipi and Bs-->Kpipi and somewhat larger in Bs-->K[overline K]pi. The first processes imply a precise linear relation between [overline rho ] and [overline eta ], with a measurable slope and an intercept at [overline eta ]=0 involving a theoretical error of 0.03. The decays Bs-->Kpipi permit a measurement of gamma involving a theoretical error below a degree. We note that while time-dependence is required when studying B⁰ decays at the Upsilon(4S), it may not be needed when studying Bs decays at hadronic colliders.

Hadron optics in three-dimensional invariant coordinate space from deeply virtual Compton scattering

S. J. Brodsky, D. Chakrabarti, A. Harindranath, A. Mukherjee, and J. P. Vary

Published 3 January 2007 (25 pages)
014003 Full Text: PDF (820 kB) | Buy Article

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The Fourier transform of the deeply virtual Compton scattering amplitude (DVCS) with respect to the skewness parameter zeta=Q²/2p·q can be used to provide an image of the target hadron in the boost-invariant variable sigma, the coordinate conjugate to light-front time tau=t+z/c. As an illustration, we construct a consistent covariant model of the DVCS amplitude and its associated generalized parton distributions using the quantum fluctuations of a fermion state at one loop in QED, thus providing a representation of the light-front wave functions (LFWFs) of a lepton in sigma space. A consistent model for hadronic amplitudes can then be obtained by differentiating the light-front wave functions with respect to the bound-state mass. The resulting DVCS helicity amplitudes are evaluated as a function of sigma and the impact parameter b-vector[perpendicular], thus providing a light-front image of the target hadron in a frame-independent three-dimensional light-front coordinate space. Models for the LFWFs of hadrons in (3+1) dimensions displaying confinement at large distances and conformal symmetry at short distances have been obtained using the AdS/CFT method. We also compute the LFWFs in this model in invariant three-dimensional coordinate space. We find that, in the models studied, the Fourier transform of the DVCS amplitudes exhibit diffraction patterns. The results are analogous to the diffractive scattering of a wave in optics where the distribution in sigma measures the physical size of the scattering center in a one-dimensional system.

Final state interaction effects in near threshold enhancement of the p[overline p] mass spectrum in B and J/psi decays

D. R. Entem and F. Fernández

Published 3 January 2007 (8 pages)
014004 Full Text: PDF (310 kB) | Buy Article

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A near threshold enhancement in the p[overline p] invariant mass spectrum has been reported by the BELLE, BES, and BABAR collaborations for several B and J/psi decays. This enhancement has been interpreted as a narrow baryonium state X(1835). We investigate its nature using a p[overline p] interaction derived from a constituent quark model. This interaction does not show any p[overline p] bound state but a ³P0 resonance. We show that p[overline p] final state interaction can reproduce the mass dependence of the p[overline p] mass spectrum close to the threshold observed in different B and J/psi decays.

Can the X(3872) be a 1⁺⁺ four-quark state?

R. D. Matheus, S. Narison, M. Nielsen, and J.-M. Richard

Published 5 January 2007 (12 pages)
014005 Full Text: PDF (438 kB) | Buy Article

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We use QCD spectral sum rules to test the nature of the meson X(3872), assumed to be an exotic four-quark (c[overline c]q[overline q]) state with J^PC=1⁺⁺. For definiteness, we work with the diquark-antidiquark current proposed recently, at leading order in alphas, consider the contributions of higher dimension condensates and keep terms which are linear in the light quark mass mq. We find MX=(3925±127) MeV which is compatible, within the errors, with the experimental candidate X(3872), while the SU(3) breaking-terms lead to an unusual mass-splitting MX^s-MX=-(61±30) MeV. The mass-difference between the neutral states due to isospin violation is about (2.6~3.9) MeV. For the b-quark, we predict MXb=(10144±106) MeV for the Xb(b[overline b]q[overline q]), which is much below the [overline B]B^* threshold, and for the Xb^s(b[overline b]s[overline s]), a mass-splitting MXb^s-MXb=-(121±182) MeV. Our analysis also indicates that the mass-splitting between the ground state and the radial excitation of about (225~250) MeV is much smaller than in the case of ordinary mesons and is (within the errors) flavor-independent. We also extract the decay constants, analogous to fpi, of such mesons, which are useful for further studies of their leptonic and hadronic decay widths. The uncertainties of our estimates are mainly due to the ones from the c and b quark masses.

Strong decays of charmed baryons in heavy hadron chiral perturbation theory

Hai-Yang Cheng and Chun-Khiang Chua

Published 8 January 2007 (14 pages)
014006 Full Text: PDF (234 kB) | Buy Article

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Strong decays of charmed baryons are analyzed in the framework of heavy hadron chiral perturbation theory (HHChPT) in which heavy quark symmetry and chiral symmetry are synthesized. HHChPT works excellently for describing the strong decays of s-wave charmed baryons. For L=1 orbitally excited states, two of the unknown couplings, namely, h2 and h10, are determined from the resonant Lambdac⁺pipi mode produced in the Lambdac(2593) decay and the width of Sigmac(2800), respectively. Predictions for the strong decays of the p-wave charmed baryon states Lambdac(2625), Xic(2790) and Xic(2815) are presented. Since the decay Lambdac(2593)⁺-->Lambdac⁺pipi receives nonresonant contributions, our value for h2 is smaller than the previous estimates. We also discuss the first positive-parity excited charmed baryons. We conjecture that the charmed baryon Lambdac(2880) with is an admixture of with an ; both are L=2 orbitally excited states. The potential model suggests or for Lambdac(2940)⁺. Measurements of the ratio of Sigmac^*pi/Sigmacpi will enable us to discriminate the J^P assignments for Lambdac(2940). We advocate that the J^P quantum numbers of Xic(2980) and Xic(3077) are and , respectively. Under this J^P assignment, it is easy to understand why Xic(2980) is broader than Xic(3077).

Regularities in hadron systematics, Regge trajectories and a string quark model

S. V. Chekanov and B. B. Levchenko

Published 8 January 2007 (10 pages)
014007 Full Text: PDF (652 kB) | Buy Article

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An empirical principle for the construction of a linear relationship between the total angular momentum and squared-mass of baryons is proposed. In order to examine linearity of the trajectories, a rigorous least-squares regression analysis was performed. Unlike the standard Regge-Chew-Frautschi approach, the constructed trajectories do not have nonlinear behavior. A similar regularity may exist for lowest-mass mesons. The linear baryonic trajectories are well described by a semiclassical picture based on a spinning relativistic string with tension. The obtained numerical solution of this model was used to extract the (di)quark masses.

Leptonic widths of heavy quarkonia: S-wave QCD/NRQCD matching coefficients for the electromagnetic vector annihilation current at [script O](alpha_sv²)

A. Hart, G. M. von Hippel, and R. R. Horgan

Published 9 January 2007 (15 pages)
014008 Full Text: PDF (414 kB) | Buy Article

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We construct the S-wave part of the electromagnetic vector annihilation current to [script O](alphasv²) on the lattice for heavy quarks whose dynamics are described by the NRQCD action, and v is the nonrelativistic quark velocity inside the meson. The lattice vector current for Q[overline Q] annihilation is expressed as a linear combination of lattice operators with quantum numbers L=0, J^P=1^-, and the coefficients are determined by matching this lattice current to the corresponding continuum current in QCD to O(v²) at one-loop. The annihilation channel gives a complex amplitude and a proper choice for the contours of integration is needed; a simple Wick rotation is not possible. In this way, and with a careful choice of subtraction functions in the numerical integration, the Coulomb-exchange and infrared singularities appearing in the amplitudes are successfully treated. The matching coefficients are given as a function of the heavy quark mass Ma in lattice units. An automated vertex generation program written in Python is employed, allowing us to use a realistic NRQCD action and an improved gluon lattice action. A change in the definition of either action is easily accommodated in this procedure. The final result, when combined with lattice simulation results, describes the electromagnetic decays of heavy quarkonia, notably the Upsilon meson.

Weak hadronic decays of charmed mesons emitting pseudoscalar and axial-vector mesons

Neelesh Sharma and R. C. Verma

Published 11 January 2007 (9 pages)
014009 Full Text: PDF (136 kB) | Buy Article

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In this paper, we investigate phenomenologically several weak decays of charmed mesons emitting a pseudoscalar meson and an axial-vector meson. Decay amplitudes are obtained using the factorization scheme in the spectator quark model. Branching ratios for the Cabibbo angle-favored, Cabibbo angle-suppressed, and Cabibbo angle-doubly-suppressed decays are obtained and compared with available experimental results.

Azimuthal dependence of the heavy quark initiated contributions to DIS

L. N. Ananikyan and N. Ya. Ivanov

Published 11 January 2007 (9 pages)
014010 Full Text: PDF (242 kB) | Buy Article

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We analyze the azimuthal dependence of the heavy-quark-initiated contributions to the lepton-nucleon deep inelastic scattering (DIS). First we derive the relations between the parton-level semi-inclusive structure functions and the helicity gamma^*Q cross sections in the case of arbitrary values of the heavy quark mass. Then the azimuth-dependent [script O](alphas) lepton-quark DIS is calculated in the helicity basis. Finally, we investigate numerically the properties of the cosphi and cos2phi distributions caused by the photon-quark scattering (QS) contribution. It turns out that, contrary to the basic photon-gluon fusion (GF) component, the QS mechanism is practically cos2phi-independent. This fact implies that measurements of the azimuthal distributions in charm leptoproduction could directly probe the charm density in the proton.

Collective quantization of axially symmetric gravitating B=2 skyrmion

Hisayuki Sato, Nobuyuki Sawado, and Noriko Shiiki

Published 12 January 2007 (14 pages)
014011 Full Text: PDF (1333 kB) | Buy Article

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In this paper we perform collective quantization of an axially symmetric skyrmion with baryon number two. The rotational and isorotational modes are quantized to obtain the static properties of a deuteron and other dibaryonic objects such as masses, charge densities, and magnetic moments. We discuss how gravity affects those observables.

Traveling waves and the renormalization group improved Balitsky-Kovchegov equation

Rikard Enberg

Published 16 January 2007 (11 pages)
014012 Full Text: PDF (269 kB) | Buy Article

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I study the incorporation of renormalization group (RG) improved BFKL kernels in the Balitsky-Kovchegov (BK) equation which describes parton saturation. The RG improvement takes into account important parts of the next-to-leading and higher-order logarithmic corrections to the kernel. The traveling wave front method for analyzing the BK equation is generalized to deal with RG-resummed kernels, restricting to the interesting case of fixed QCD coupling. The results show that the higher-order corrections suppress the rapid increase of the saturation scale with increasing rapidity. I also perform a diffusive differential equation approximation, which illustrates that some important qualitative properties of the kernel change when including RG corrections.

D wave heavy mesons

Wei Wei, Xiang Liu, and Shi-Lin Zhu

Published 16 January 2007 (10 pages)
014013 Full Text: PDF (207 kB) | Buy Article

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We first extract the binding energy [overline Lambda ] and decay constants of the D wave heavy meson doublets (1^-,2^-) and (2^-,3^-) with QCD sum rule in the leading order of heavy quark effective theory. Then we study their pionic (pi,K,eta) couplings using the light-cone sum rule, from which the parameter [overline Lambda ] can also be extracted. We then calculate the pionic decay widths of the strange/nonstrange D wave heavy D/B mesons and discuss the possible candidates for the D wave charm-strange mesons. Further experimental information, such as the ratio between Dseta and DK modes, will be very useful to distinguish various assignments for DsJ(2860 2715).

Transverse-momentum dependent factorization for gamma^*pi⁰-->gamma

J. P. Ma and Q. Wang

Published 17 January 2007 (13 pages)
014014 Full Text: PDF (279 kB) | Buy Article

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With a consistent definition of transverse-momentum dependent (TMD) light-cone wave function, we show that the amplitude for the process gamma^*pi⁰-->gamma can be factorized when the virtuality of the initial photon is large. In contrast to the collinear factorization in which the amplitude is factorized as a convolution of the standard light-cone wave function and a hard part, the TMD factorization yields a convolution of a TMD light-cone wave function, a soft factor and a hard part. We explicitly show that the TMD factorization holds at one-loop level. It is expected that the factorization holds beyond one-loop level because the cancellation of soft divergences is on a diagram-by-diagram basis. We also show that the TMD factorization helps to resum large logarithms of type ln²x.

Inhomogeneity driven by Higgs instability in a gapless superconductor

Ioannis Giannakis, Defu Hou, Mei Huang, and Hai-cang Ren

Published 19 January 2007 (16 pages)
014015 Full Text: PDF (321 kB) | Buy Article

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The fluctuations of the Higgs and pseudo Nambu-Goldstone fields in the 2-flavor color superconductivity (2SC) phase with mismatched pairing are described in the nonlinear realization framework of the gauged Nambu-Jona-Lasinio model. In the gapless 2SC phase, not only Nambu-Goldstone currents can be spontaneously generated, but also the Higgs field exhibits instablity. The Nambu-Goldstone currents generation indicates the formation of the single plane wave Larkin-Ovchinnikov-Fulde-Ferrel state and breaks rotation symmetry, while the Higgs instability favors spatial inhomogeneity and breaks translation invariance. In this paper, we focus on the Higgs instability which has not drawn much attention yet. The Higgs instability cannot be removed without a long range force, thus it persists in the gapless superfluidity and induces phase separation. In the case of gapless 2-flavor color superconductivity state, the Higgs instability can only be partially removed by the electric Coulomb energy. However, it is not excluded that the Higgs instability might be completely removed in the charge neutral gapless color-flavor locked phase by the color Coulomb energy.

Next-to-leading order versus quark off-shellness and intrinsic k_T in the Drell-Yan process

O. Linnyk, S. Leupold, and U. Mosel

Published 19 January 2007 (10 pages)
014016 Full Text: PDF (565 kB) | Buy Article

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We calculate the effects of next-to-leading order perturbative QCD as well as of the quark transverse motion and off-shellness on the Drell-Yan process cross section. By studying the s-->[infinity] behavior of the cross section in these approaches, we find that the effects of quark off-shellness and intrinsic-kT parametrize those of higher twists. In particular, the off-shellness of partons generates part of the K-factor type corrections to the leading order cross section. Higher-twist contributions to the pT-spectrum of the Drell-Yan pairs are found to be large for presently accessible energies. The evolution of quark off-shellness distribution with the hard scale is also studied.

Clues for the existence of two K₁(1270) resonances

L. S. Geng, E. Oset, L. Roca, and J. A. Oller

Published 22 January 2007 (13 pages)
014017 Full Text: PDF (1532 kB) | Buy Article

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The axial-vector meson K1(1270) was studied within the chiral unitary approach, where it was shown that it has a two-pole structure. We reanalyze the high-statistics WA3 experiment K^-p-->K^-pi⁺pi^-p at 63 GeV, which established the existence of both K1(1270) and K1(1400), and we show that it clearly favors our two-pole interpretation. We also reanalyze the traditional K-matrix interpretation of the WA3 data and find that the good fit of the data obtained there comes from large cancellations of terms of unclear physical interpretation.

Branching ratio and CP asymmetry of B⁰-->eta^([prime])eta^([prime]) decays in the perturbative QCD approach

Zhen-jun Xiao, Dong-qin Guo, and Xin-fen Chen

Published 23 January 2007 (16 pages)
014018 Full Text: PDF (572 kB) | Buy Article

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We calculate the CP-averaged branching ratios and CP-violating asymmetries for B⁰-->etaeta, etaeta^[prime] and eta^[prime]eta^[prime] decays by employing the perturbative QCD (pQCD) factorization approach. The pQCD predictions for the CP-averaged branching ratios are Br(B⁰-->etaeta)[approximate]0.67×10^-7, Br(B⁰-->etaeta^[prime])[approximate]0.18×10^-7, and Br(B⁰-->eta^[prime]eta^[prime])[approximate]0.11×10^-7, which are consistent with currently available experimental upper limits. We also predict large CP-violating asymmetries for the considered three decay modes, which can be tested by the future B meson experiments.

B-->KK^* decays in the perturbative QCD approach

Libo Guo, Qian-gui Xu, and Zhen-jun Xiao

Published 23 January 2007 (16 pages)
014019 Full Text: PDF (470 kB) | Buy Article

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We calculate the branching ratios and CP-violating asymmetries for B⁰-->K⁰[overline K]^*0, [overline K]⁰K^*0, K⁺K^*-, K^-K^*+, and B⁺-->K⁺[overline K]^*0, and [overline K]⁰K^*+ decays by employing the low energy effective Hamiltonian and the perturbative QCD (pQCD) factorization approach. The theoretical predictions for the branching ratios are Br(B⁰/[overline B]⁰-->K^±K^*-/+)[approximate]7.4×10^-8, Br(B⁰/[overline B]⁰-->K⁰[overline K]^*0([overline K]⁰K^*0))[approximate]19.6×10^-7, Br(B⁺-->K⁺[overline K]^*0)[approximate]3×10^-7 and Br(B⁺-->K^*+[overline K]⁰)[approximate]18.3×10^-7, which are consistent with currently available experimental upper limits. We also predict large CP-violating asymmetries in these decays: ACP^dir(K^±[overline K]^*0)[approximate]-20%, ACP^dir(K^*±[overline K]⁰)[approximate]-49%, which can be tested by the forthcoming B meson experiments.

Supersymmetric QCD corrections to single top quark production at hadron colliders

Jia Jun Zhang, Chong Sheng Li, Zhao Li, and Li Lin Yang

Published 23 January 2007 (19 pages)
014020 Full Text: PDF (1280 kB) | Buy Article

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We present the calculations of the supersymmetric QCD corrections to the total cross sections for single top production at the Fermilab Tevatron and the CERN Large Hadron Collider in the minimal supersymmetric standard model. Our results show that, for the s-channel and t-channel, the supersymmetric QCD corrections are at most about 1%, but for the associated production process pp-->tW, the supersymmetric QCD corrections increase the total cross sections significantly, which can reach about 6% for most values of the parameters. Thus, the supersymmetric QCD corrections should be taken into consideration in future high precision experimental analyses for top physics.

Deep inelastic pion electroproduction at threshold

V. M. Braun, D. Yu. Ivanov, A. Lenz, and A. Peters

Published 25 January 2007 (16 pages)
014021 Full Text: PDF (297 kB) | Buy Article

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We consider the cross section of the deep inelastic pion electroproduction on a proton target at threshold for Q² in the region 5–10 GeV². The corresponding amplitudes are described in terms of two form factors which we calculate using light-cone sum rules to leading order in QCD and including higher twist corrections. Our results suggest a considerable change from a small Q² region that can be treated in the soft-pion limit using current algebra. In particular, we obtain a pi⁰ to pi⁺ production ratio of order 1/3 and significant nucleon helicity-flip contributions.

Momentum flow correlations from event shapes: Factorized soft gluons and soft-collinear effective theory

Christopher Lee and George Sterman

Published 26 January 2007 (15 pages)
014022 Full Text: PDF (239 kB) | Buy Article

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The distributions of two-jet event shapes contain information on hadronization in QCD. Near the two-jet limit, these distributions can be described by convolutions of nonperturbative event shape functions with the same distributions calculated in resummed perturbation theory. The shape functions, in turn, are determined by correlations of momentum flow operators with each other and with lightlike Wilson lines, which describe the coupling of soft, wide-angle radiation to jets. We observe that leading power corrections to the mean values of event shapes are determined by the correlation of a single momentum flow operator with the relevant Wilson lines. This generalizes arguments for the universality of leading power corrections based on the low-scale behavior of the running coupling or resummation. We also show how a study of the angularity event shapes can provide information on correlations involving multiple momentum flow operators, giving a window to the system of QCD dynamics that underlies the variety of event shape functions. In deriving these results, we review, develop and compare factorization techniques in conventional perturbative QCD and soft-collinear effective theory (SCET). We give special emphasis to the elimination of double counting of momentum regions in these two formalisms.

Parton transverse momenta and direct photon production in hadronic collisions at high energies

T. Pietrycki and A. Szczurek

Published 25 January 2007 (20 pages)
014023 Full Text: PDF (3470 kB) | Buy Article

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The invariant cross sections for direct photon production in hadron-hadron collisions are calculated for several initial energies (SPS, ISR, Sp[overline p]S, RHIC, Tevatron, LHC) including initial parton transverse momenta within the formalism of unintegrated parton distributions (UPDF). Different approaches from the literature are compared and discussed. A special emphasis is put on the Kimber-Martin-Ryskin (KMR) distributions and their extension into the soft region. Sum rules for UPDFs are formulated and discussed in detail. We find a violation of naive number sum rules for the KMR UPDFs. An interesting interplay of perturbative (large kt²) and nonperturbative (small kt²) regions of UPDFs in the production of both soft and hard photons is identified. The kt-factorization approach with the KMR UPDFs is inconsistent with the collinear approach at large transverse momenta of photons. Kwieciński UPDFs provide very good description of all world data, especially at super proton synchrotron (SPS) and intersecting storage rings (ISR) energies. Off-shell effects are discussed and quantified. Predictions for the CERN LHC are given. Very forward/backward regions in rapidity at LHC energy are discussed and a possibility to test unintegrated gluon distributions (UGDF) is presented.

Semiinclusive hadronic B decays as null tests of the standard model

A. Soni and J. Zupan

Published 26 January 2007 (8 pages)
014024 Full Text: PDF (163 kB) | Buy Article

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We propose a new set of observables that can be used as experimental null tests of the Standard Model in charged and neutral B decays. The CP asymmetries in hadronic decays of charged B mesons into inclusive final states containing at least one of the following mesons: KS,L, eta^[prime], c[overline c] bound states or neutral K^* or D mesons, for all of which a U-spin rotation is equivalent to a CP conjugation, are CKM suppressed and furthermore vanish in the exact U-spin limit. We show how this reduces the theoretical error by using Soft Collinear Effective Theory to calculate the CP asymmetries for KS,LXs+d, K^*Xs+d and eta^[prime]Xs+d final states in the endpoint region. For these CP asymmetries only the flavor and not the charge of the decaying B meson needs to be tagged up to corrections of NLO in 1/mb, making the measurements more accessible experimentally.

Ordinary muon capture on a proton in manifestly Lorentz invariant baryon chiral perturbation theory

Shung-ichi Ando and Harold W. Fearing

Published 26 January 2007 (21 pages)
014025 Full Text: PDF (465 kB) | Buy Article

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The amplitude for ordinary muon capture on the proton is evaluated, through the first four orders in the expansion parameter, in a manifestly Lorentz invariant form of baryon chiral perturbation theory. Expressions for the low energy constants in terms of physical quantities are obtained in each of the several renormalization schemes which have been proposed for forcing the relativistic approach to obey the same counting rules as obtained in heavy baryon chiral perturbation theory. The advantages and disadvantages of these schemes are discussed, using the muon capture results as an example, with the aim of gaining insight as to which scheme is preferable for practical calculations.

Transverse spin effects of sea quarks in unpolarized nucleons

Zhun Lu, Bo-Qiang Ma, and Ivan Schmidt

Published 29 January 2007 (7 pages)
014026 Full Text: PDF (404 kB) | Buy Article

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We calculate the nonzero Boer-Mulders functions of sea quarks inside the proton in a meson-baryon fluctuation model. The results show that the transverse spin effects of sea quarks in an unpolarized nucleon are sizable. Using the obtained antiquark Boer-Mulders functions, we estimate the cos2phi asymmetries in the unpolarized pp and pD Drell-Yan processes at FNAL E866/NuSea experiments. The prediction for the cos2phi asymmetries in the unpolarized pp Drell-Yan process at the BNL Relativistic Heavy Ion Collider (RHIC) is also given.

Test of the reaction mechanism for gammaN-->KLambda(1520) using the polarized photon

Seung-il Nam, Ki-Seok Choi, Atsushi Hosaka, and Hyun-Chul Kim

Published 30 January 2007 (7 pages)
014027 Full Text: PDF (400 kB) | Buy Article

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We study the reaction mechanism for the photoproduction of the Lambda(1520), based on an effective Lagrangian approach. We investigate each contribution of the s-, u-, t-channel processes and contact term, separately. One of the most characteristic features of this reaction is the contact-term dominance which governs the photoproduction from the proton, when the K^*-exchange contribution is possibly not too large. We suggest several different ways of the polarizations and arrangement of the beam and target to understand the role of each contribution separately in future experiments.

Charm photoproduction at DESY HERA: k_T factorization versus experimental data

A. V. Lipatov and N. P. Zotov

Published 31 January 2007 (14 pages)
014028 Full Text: PDF (905 kB) | Buy Article

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We calculate the cross section of charm photoproduction at HERA collider in the framework of the kT-factorization QCD approach. Our analysis covers the inclusive charm production as well as charm and associated jet production processes. Both photon-gluon and gluon-gluon fusion mechanisms are taken into account. The unintegrated gluon densities in a proton and in a photon obtained from the full Ciafaloni-Catani-Fiorani-Marchesini (CCFM), from unified Balitsky-Fadin-Kuraev-Lipatov–Dokshitzer-Gribov-Lipatov-Altarelli-Parizi evolution equations as well as from the Kimber-Martin-Ryskin prescription are used. Our theoretical results are compared with the recent experimental data taken by the H1 and ZEUS collaborations at HERA. Special attention is put on the specific angular correlations which can provide unique information about noncollinear gluon evolution dynamics.

Model independent approach to studies of the confining dual Abrikosov vortex in SU(2) lattice gauge theory

Richard W. Haymaker and Takayuki Matsuki

Published 9 January 2007 (18 pages)
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We address the problem of determining the type I, type II or borderline dual superconductor behavior in maximal Abelian gauge SU(2) through the study of the dual Abrikosov vortex. We find that significant electric currents in the simulation data call into question the use of the dual Ginzburg-Landau Higgs model in interpreting the data. Further, two definitions of the penetration depth parameter take two different values. The splitting of this parameter into two is intricately connected to the existence of electric currents. It is important in our approach that we employ definitions of flux and electric and magnetic currents that respect Maxwell equations exactly for lattice averages independent of lattice spacings. Applied to specific Wilson loop sizes, our conclusions differ from those that use the dual GLH model.

Phase diagram at finite temperature and quark density in the strong coupling limit of lattice QCD for color SU(3)

N. Kawamoto, K. Miura, A. Ohnishi, and T. Ohnuma

Published 11 January 2007 (18 pages)
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We study the phase diagram of quark matter at finite temperature (T) and chemical potential (µ) in the strong coupling limit of lattice QCD for color SU(3). We derive an analytical expression of the effective free energy as a function of T and µ, including baryon effects. The finite temperature effects are evaluated by integrating over the temporal link variable exactly in the Polyakov gauge with an antiperiodic boundary condition for fermions. The obtained phase diagram shows the first and the second order phase transition at low and high temperatures, respectively, and those are separated by the tricritical point in the chiral limit. Baryon has effects to reduce the effective free energy and to extend the hadron phase to a larger µ direction at low temperatures.

Chiral extrapolation of g_A with explicit Delta(1232) degrees of freedom

M. Procura, B. U. Musch, T. R. Hemmert, and W. Weise

Published 12 January 2007 (13 pages)
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An updated and extended analysis of the quark-mass dependence of the nucleon's axial-vector coupling constant gA is presented in comparison with state-of-the-art lattice QCD results. Special emphasis is placed on the role of the Delta(1232) isobar. It is pointed out that standard chiral perturbation theory of the pion-nucleon system at order p⁴ fails to provide an interpolation between the lattice data and the physical point. In constrast, a version of chiral effective field theory with explicit inclusion of the Delta(1232) proves to be successful. Detailed error analysis and convergence tests are performed. Integrating out the Delta(1232) as an explicit degree of freedom introduces uncontrolled errors for pion masses mpi>~300 MeV.

Modified SO(3) lattice gauge theory at T[not-equal]0 with parallel tempering: Monopole and vortex condensation

G. Burgio, M. Fuhrmann, W. Kerler, and M. Müller-Preussker

Published 17 January 2007 (14 pages)
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The deconfinement transition is studied close to the continuum limit of SO(3) lattice gauge theory. High barriers for tunneling among different twist sectors causing loss of ergodicity for local update algorithms are circumvented by means of parallel tempering. We compute monopole and center vortex free energies both within the confining phase and through the deconfinement transition. We discuss in detail the general problem of defining order parameters for adjoint actions.

Electromagnetic corrections in partially quenched chiral perturbation theory

Johan Bijnens and Niclas Danielsson

Published 19 January 2007 (11 pages)
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We introduce photons in partially quenched chiral perturbation theory and calculate the resulting electromagnetic loop-corrections at next-to-leading-order (NLO) for the charged meson masses and decay constants. We also present a numerical analysis to indicate the size of the different corrections. We show that several phenomenologically relevant quantities can be calculated consistently with photons which couple only to the valence quarks, allowing the use of gluon configurations produced without dynamical photons.

Quarkonium correlators and spectral functions at zero and finite temperature

A. Jakovác, P. Petreczky, K. Petrov, and A. Velytsky

Published 19 January 2007 (22 pages)
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We study quarkonium correlators and spectral functions at zero and finite temperature using the anisotropic Fermilab lattice formulation with anisotropy xi=2 and 4. To control cut-off effects we use several different lattice spacings. The spectral functions were extracted from lattice correlators with maximum entropy method based on a new algorithm. We find evidence for the survival of 1S quarkonium states in the deconfined medium till relatively high temperatures as well as for dissolution of 1P quarkonium states right above the deconfinement temperature.

Proton decay matrix elements with domain-wall fermions

Y. Aoki, C. Dawson, J. Noaki, and A. Soni

Published 25 January 2007 (24 pages)
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Hadronic matrix elements of operators relevant to nucleon decay in grand unified theories are calculated numerically using lattice QCD. In this context, the domain-wall fermion formulation, combined with nonperturbative renormalization, is used for the first time. These techniques bring reduction of a large fraction of the systematic error from the finite lattice spacing. Our main effort is devoted to a calculation performed in the quenched approximation, where the direct calculation of the nucleon to pseudoscalar matrix elements as well as the indirect estimate of them from the nucleon to vacuum matrix elements are performed. First results, using two flavors of dynamical domain-wall quarks for the nucleon to vacuum matrix elements, are also presented to address the systematic error of quenching, which appears to be small compared to the other errors. Our results suggest that the representative values for the low-energy constants from the nucleon to vacuum matrix elements are given as |alpha|~=|beta|~=0.01 GeV³. For a more reliable estimate of the physical low-energy matrix elements, it is better to use the relevant form factors calculated in the direct method. The direct method tends to give a smaller value of the form factors, compared to the indirect one, thus enhancing the proton lifetime; indeed, for the pi⁰ final state the difference between the two methods is quite appreciable.

Infrared behavior of the Faddeev-Popov operator in Coulomb gauge QCD

Y. Nakagawa, A. Nakamura, T. Saito, and H. Toki

Published 31 January 2007 (7 pages)
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We calculate the eigenvalue distribution of the Faddeev-Popov operator in Coulomb gauge QCD using quenched SU(3) lattice simulation. In the confinement phase, the density of the low-lying eigenvalues increases with lattice volume, and the confinement criterion is satisfied. Moreover, even in the deconfinement phase, the behavior of the FP eigenvalue density is qualitatively the same as in the confinement phase. This is consistent with the fact that the color-Coulomb potential is not screened in the deconfined phase.

Low scale seesaw, electron electric dipole moment, and leptogenesis in a model with spontaneous CP violation

Mu-Chun Chen and K. T. Mahanthappa

Published 2 January 2007 (9 pages)
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Strong correlations between leptogenesis and low energy CP violating leptonic processes have been shown by us to exist in the minimal left-right symmetric model with spontaneous CP violation. In this note, we investigate the implications of this model for the electric dipole moment of the electron. With an additional broken U(1)S symmetry, the seesaw scale can be lowered to close to the electroweak scale. This additional symmetry also makes the connection between CP violation in quark sector to that in the lepton sector possible.

Collider signals of top quark flavor violation from a warped extra dimension

Kaustubh Agashe, Gilad Perez, and Amarjit Soni

Published 5 January 2007 (5 pages)
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We study top quark flavor violation in the framework of a warped extra dimension with the Standard Model (SM) fields propagating in the bulk. Such a scenario provides solutions to both the Planck-weak hierarchy problem and the flavor puzzle of the SM without inducing a flavor problem. We find that, generically, tcZ couplings receive a huge enhancement, in particular, the right-handed ones can be [script O](1%). This results in BR(t-->cZ) at or above the sensitivity of the Large Hadron Collider (LHC). At the International Linear Collider (ILC), single top production, via e⁺e^--->t[overline c], can be a striking signal for this scenario. In particular, it represents a physics topic of critical importance that can be explored even with a relatively low energy option, close to the tc threshold. At both the LHC and the ILC, angular distributions can probe the above prediction of dominance of right-handed couplings.

A new custodian for a realistic Higgsless model

Giacomo Cacciapaglia, Csaba Csáki, Guido Marandella, and John Terning

Published 10 January 2007 (7 pages)
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We present an example of a realistic Higgsless model that makes use of alternative SU(2)R assignments for the top and bottom quarks recently proposed by Agashe et al. which results in an enhanced custodial symmetry. Using these new representations reduces the deviations in the Zb[script-l][overline b][script-l] coupling to ~4% for a wide range of parameters, while this remaining correction can also be eliminated by varying the localization parameter (bulk mass) for br.

Pair production of heavy MSSM charged and neutral Higgs bosons in multi-TeV e⁺e^- collisions at the Compact Linear Collider

Elias Coniavitis and Arnaud Ferrari

Published 11 January 2007 (16 pages)
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In the theoretical framework of the minimal supersymmetric extension of the standard model (MSSM), we study the pair production of heavy charged and neutral Higgs bosons in e⁺e^- collisions with a center-of-mass energy of 3 TeV, at the Compact Linear Collider (CLIC). The high-energy beam-beam effects at the interaction point are taken into account in our simulations. With an integrated luminosity of 3000 fb^-1, the hadronic cascade decays of H⁺H^- and A⁰H⁰ pairs can be observed over a wide range of Higgs boson masses, extending beyond 1 TeV. The Higgs mass parameter mA can be derived from a chi²-analysis, and the corresponding statistical error was found to be smaller than 1%. In addition, by comparing the signal rates of different decay channels, one can determine the ratio between the vacuum expectation values tanbeta with a good accuracy in the intermediate region, i.e. when tanbeta lies between 6 and 11 typically.

Supersymmetry without the desert

Yasunori Nomura and David Poland

Published 24 January 2007 (26 pages)
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Naturalness of electroweak symmetry breaking in weak scale supersymmetric theories may suggest the absence of the conventional supersymmetric desert. We present a simple, realistic framework for supersymmetry in which (most of) the virtues of the supersymmetric desert are naturally reproduced without having a large energy interval above the weak scale. The successful supersymmetric prediction for the low-energy gauge couplings is reproduced due to a gauged R symmetry present in the effective theory at the weak scale. The observable sector superpotential naturally takes the form of the next-to-minimal supersymmetric standard model, but without being subject to the Landau pole constraints up to the conventional unification scale. Supersymmetry breaking masses are generated by the F-term and D-term vacuum expectation values of singlet and U(1)R gauge fields, as well as by anomaly mediation, at a scale not far above the weak scale. We study the resulting pattern of supersymmetry breaking masses in detail and find that it can be quite distinct. We construct classes of explicit models within this framework, based on higher-dimensional unified theories with TeV-sized extra dimensions. A similar model based on a non-R symmetry is also presented. These models have a rich phenomenology at the TeV scale, and allow for detailed analyses of, e.g., electroweak symmetry breaking.

Modification of the unitarity relation for sin2beta-V_ub in supersymmetric models

Bhaskar Dutta and Yukihiro Mimura

Published 25 January 2007 (11 pages)
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Recently, a more than 2sigma discrepancy has been observed between the well measured inclusive value of Vub and the predicted value of Vub from the unitarity triangle fit using the world average value of sin2beta. We attempt to resolve this tension in the context of grand unified SO(10) and SU(5) models where the neutrino mixing matrix is responsible for flavor changing neutral current at the weak scale and the models with nonproportional A-terms (can be realized simply in the context of intersecting D-brane models) and investigate the interplay between the constraints arising from Bs,d-[overline B]s,d mixings, epsilonK, Br(tau-->µgamma), Br(µ-->egamma) and a fit of this new discrepancy. We also show that the ongoing measurement of the phase of Bs mixing will be able to identify the grand unified model. The measurement of Br(tau-->egamma) will also be able to test these scenarios, especially the models with nonproportional A-terms.

Constraints on the minimal supergravity parameter space from NLO calculation of isospin asymmetry in B-->K^*gamma

M. R. Ahmady and F. Mahmoudi

Published 31 January 2007 (14 pages)
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The contributions of supersymmetric particles in the isospin symmetry violation in B-->K^*gamma decay mode are investigated. The model parameters are adopted from minimal Supergravity with minimal flavor violation. A complete scan of the mSUGRA parameter space has been performed, using the next to leading supersymmetric contributions to the relevant Wilson coefficients. The results are compared to recent experimental data in order to obtain constraints on the parameter space. We point out that isospin asymmetry can prove to be an interesting observable and imposes severe restrictions on the allowed parameter space, in particular, for large values of tanbeta. The constraints obtained with isospin asymmetry also appear as more restricting than the ones from the branching ratio of B-->Xsgamma.

Dispersion representations and anomalous singularities of the triangle diagram

Wolfgang Lucha, Dmitri Melikhov, and Silvano Simula

Published 3 January 2007 (10 pages)
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We discuss dispersion representations for the triangle diagram F(p1²,p2²,q²), the single dispersion representation in q² and the double dispersion representation in p1² and p2², with special emphasis on the appearance of the anomalous singularities and the anomalous cuts in these representations. For the double dispersion representation in p1² and p2², the appearance of the anomalous cut in the region q²>0 is demonstrated, and a new derivation of the anomalous double spectral density is given. We point out that the double spectral representation is particularly suitable for applications in the region of p1² and/or p2² above the two-particle thresholds. The dispersion representations for the triangle diagram in the nonrelativistic limit are studied and compared with the triangle diagram of the nonrelativistic field theory.

piN--> multi-piN scattering in the 1/N_c expansion

Herry J. Kwee and Richard F. Lebed

Published 8 January 2007 (11 pages)
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We extend the 1/Nc expansion meson-baryon scattering formalism to cases in which the final state contains more than two particles. We first show that the leading-order large Nc processes proceed through resonant intermediate states (e.g., rhoN or piDelta). We then tabulate linear amplitude expressions for relevant processes and find that the pole structure of baryon resonances can be uniquely identified by their (non)appearance in etaN or mixed partial-wave piDelta final states. We also show that quantitative predictions of piN to piDelta branching ratios predicted at leading order alone do not agree with measurements, but the inclusion of 1/Nc corrections is ample to explain the discrepancies.

Deep inelastic scattering near the endpoint in soft-collinear effective theory

Junegone Chay and Chul Kim

Published 8 January 2007 (22 pages)
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We apply the soft-collinear effective theory to deep inelastic scattering near the endpoint region. The forward scattering amplitude and the structure functions are shown to factorize as a convolution of the Wilson coefficients, the jet functions, and the parton distribution functions. The behavior of the parton distribution functions near the endpoint region is considered. It turns out that it evolves with the Altarelli-Parisi kernel even in the endpoint region, and the parton distribution function can be factorized further into a collinear part and the soft Wilson line. The factorized form for the structure functions is obtained by the two-step matching, and the radiative corrections or the evolution for each factorized part can be computed in perturbation theory. We present the radiative corrections of each factorized part to leading order in alphas, including the zero-bin subtraction for the collinear part.

Classes of confining gauge field configurations

Marc Wagner

Published 9 January 2007 (18 pages)
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We present a numerical method to compute path integrals in effective SU(2) Yang-Mills theories. The basic idea is to approximate the Yang-Mills path integral by summing over all gauge field configurations, which can be represented as a linear superposition of a small number of localized building blocks. With a suitable choice of building blocks many essential features of SU(2) Yang-Mills theory can be reproduced, particularly confinement. The analysis of our results leads to the conclusion that topological charge as well as extended structures are essential elements of confining gauge field configurations.

The Greisen equation explained and improved

Rainer W. Schiel and John P. Ralston

Published 19 January 2007 (7 pages)
016005 Full Text: PDF (421 kB) | Buy Article

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Analytic description of the evolution of cosmic ray showers is dominated by the Greisen equation nearly five decades old. We present an alternative approach with several advantages. Among the new features are a prediction of the differential distribution, replacing Greisen's form which fails to be positive definite. Explicit comparison with Monte Carlo simulations shows excellent agreement after a few radiation lengths of development. We find a clear connection between Monte Carlo adjustment of Greisen's form and underlying physics, and present a concise derivation with all steps explicit. We also reconstruct the steps needed to reproduce Greisen's approximate formula, which appears not to have been published previously.

All one-loop maximally helicity violating gluonic amplitudes in QCD

Carola F. Berger, Zvi Bern, Lance J. Dixon, Darren Forde, and David A. Kosower

Published 24 January 2007 (35 pages)
016006 Full Text: PDF (897 kB) | Buy Article

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We use on-shell recursion relations to compute analytically the one-loop corrections to maximally helicity-violating n-gluon amplitudes in QCD. The cut-containing parts have been computed previously; our work supplies the remaining rational parts for these amplitudes, which contain two gluons of negative helicity and the rest positive, in an arbitrary color ordering. We also present formulae specific to the six-gluon cases with helicities (-+-+++) and (-++-++), as well as numerical results for six, seven, and eight gluons. Our construction of the n-gluon amplitudes illustrates the relatively modest growth in complexity of the on-shell-recursive calculation as the number of external legs increases. These amplitudes add to the growing body of one-loop amplitudes known for all n, which are useful for studies of general properties of amplitudes, including their twistor-space structure.

BRIEF REPORTS

Search for B⁺-->J/psieta^[prime]K⁺ and B⁰-->J/psieta^[prime]K_S⁰ decays

Q. L. Xie et al. (Belle Collaboration)

Published 22 January 2007 (6 pages)
017101 Full Text: PDF (242 kB) | Buy Article

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We report the results of searches for B⁺-->J/psieta^[prime]K⁺ and B⁰-->J/psieta^[prime]KS⁰ decays, using a sample of 388×10⁶ B[overline B] pairs collected with the Belle detector at the Upsilon(4S) resonance. No statistically significant signal is found for either of the two decay modes and upper limits for the branching fractions are determined to be [script B](B⁺-->J/psieta^[prime]K⁺)<8.8×10^-5 and [script B](B⁰-->J/psieta^[prime]KS⁰)<2.5×10^-5 at 90% confidence level.

Timelike form factor of the Kaon for |Q²|=M²(J/psi)

Kamal K. Seth

Published 23 January 2007 (2 pages)

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Physical Review D

January 2007

Volume 75, Number 1 , Articles (01xxxx)

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