HADRON 2009: Proceedings of the XIII International Conference on Hadron Spectroscopy
1257(2010); http://dx.doi.org/10.1063/1.3483358View Description Hide Description
The proton mass arises from spontaneous breaking of chiral symmetry and the formation of constituent quarks. Their dynamics cannot be tested by proton tomography but only by studying excited baryons. However, the number of excited baryons is much smaller than expected within quark models; even worse, the existence of many known states has been challenged in a recent analysis which includes—compared to older analyses—high‐precision data from meson factories. Hence πN elastic scattering data do not provide a well‐founded starting point of any phenomenological analysis of the baryon excitation spectrum. Photoproduction experiments now start to fill in this hole. Often, they confirm the old findings and even suggest a few new states. These results encourage attempts to compare the pattern of observed baryon resonances with predictions from quark models, from models generating baryons dynamically from meson‐nucleon scattering amplitudes, from models based on gravitational theories, and with the conjecture that chiral symmetry may be restored at high excitation energies. Best agreement is found with a simple mass formula derived within AdS/QCD. Consequences for our understanding of QCD are discussed as well as experiments which may help to decide on the validity of models.
1257(2010); http://dx.doi.org/10.1063/1.3483307View Description Hide Description
In this invited presentation I review some recent developments in the theory of charmonium that appear likely to be of importance for future experimental studies in this field. The specific areas considered are double charmonium production, LQCD studies of charmonium, recent results for hadron loops, c c̄ production cross sections at PANDA, charm molecules, and two recent developments, “charmiscelleny”.
1257(2010); http://dx.doi.org/10.1063/1.3483319View Description Hide Description
Lattice spectroscopy is becoming increasingly sophisticated. This review will introduce the methodology and describe progress made recently probing the spectrum of excitations of QCD. The focus will be on describing new developments that enable excited states, exotic quantum numbers and resonances to be explored.
1257(2010); http://dx.doi.org/10.1063/1.3483333View Description Hide Description
Light scalar mesons abound in hadron processes, like the alligators in the Florida Everglades. Moreover, scalars are intimately tied to the vacuum structure of QCD. They are the product of many decays. Consequently, a rich source of recent information about them has come from experiments producing heavy flavour mesons. Indeed, scalars will continue to dominate many of the processes to be studied at forthcoming facilities like BESIII in Beijing, FAIR at GSI Darmstadt and the GlueX experiment at JLab, making an understanding (or at least an excellent and theoretically consistent description) essential for the physics missions of these facilities.
1257(2010); http://dx.doi.org/10.1063/1.3483371View Description Hide Description
The theory of the strong interaction, Quantum Chromodynamics, has been remarkably successful in describing high‐energy and short‐distance‐scale experiments involving quarks and gluons. However, applying QCD to low energy and large‐distance‐scale experiments has been a major challenge. Chiral symmetry is one of the most fundamental symmetries in QCD and provides guiding principles to deal with strong interaction phenomena in the non‐perturbative domain. Various QCD‐inspired models predict a modification of the properties of hadrons in nuclear matter from their free‐space values. A review of experiments searching for the in‐medium modifications of light mesons and baryons will be given trying to assess if they confirm or refute these theoretical predictions.
1257(2010); http://dx.doi.org/10.1063/1.3483389View Description Hide Description
A new hadron spectroscopy program to study particle production at the central region through diffractive processes in polarized collisions at has been initiated with the STAR detector at RHIC. Staged implementation of multiple Roman Pot stations for tagging forward protons in diffractive processes allows studying for the first time the dynamics of the particle production in the diffractive processes systematically at the RHIC energy regime. The STAR detector system with complete azimuthal coverage at the central region equipped with excellent particle reconstruction capabilities enables studies of the constituent gluonic degree of freedom in double Pomeron exchange processes.
1257(2010); http://dx.doi.org/10.1063/1.3483402View Description Hide Description
We find a correspondence between semiclassical QCD quantized on the light‐front and a dual gravity model in anti—de Sitter (AdS) space, thus providing an initial approximation to QCD in its strongly coupled regime. This correspondence—light‐front holography—leads to a light‐front Hamiltonian and relativistic bound‐state wave equations that are functions of an invariant impact variable ζ which measures the separation of the quark and gluonic constituents within hadrons at equal light‐front time. The eigenvalues of the resulting light‐front Schrödinger and Dirac equations are consistent with the observed light meson and baryon spectrum, and the eigenmodes provide the light‐front wavefunctions, the probability amplitudes describing the dynamics of the hadronic constituents. The light‐front equations of motion, which are dual to an effective classical gravity theory, possess remarkable algebraic and integrability properties which are dictated by the underlying conformal properties of the theory. We extend the algebraic construction to include a confining potential while preserving the integrability of the mesonic and baryonic bound‐state equations.
1257(2010); http://dx.doi.org/10.1063/1.3483423View Description Hide Description
Hadron spectroscopy is one of the main topics within the COMPASS experiment. Three production mechanisms are used to study exotic states and to search for glueballs: diffractive and central production with pions and protons using a liquid hydrogen target and diffraction and Primakoff reactions with pions impinging on nuclear targets. While the main data taking has been performed in 2008 and 2009, where the statistics of previous experiments has been boosted by a factor 10–100, early measurements with diffractive production on nuclear targets in 2004 have confirmed the existence of an exotic state at a mass around 1.6 GeV. In this paper we report on the final analysis of our 2004 data discussing the evidence for the exotic π(1600) and show first insights into the results of the analysis from 2008 data using various final states, thus demonstrating the data quality and potential of the COMPASS data set.
1257(2010); http://dx.doi.org/10.1063/1.3483442View Description Hide Description
We review recent progress in calculating radiative transition form factors using lattice QCD. We discuss results in the charmonium region involving excited states, states of high spin and exotics. As well as highlighting interesting results involving an exotic states and a vector‐hybrid candidate, we give comparison with experimental data and models. Some lattice calculations of baryon photocouplings are also mentioned. We conclude with some comments on future prospects.
1257(2010); http://dx.doi.org/10.1063/1.3483449View Description Hide Description
The Tevatron experiments have each accumulated about good data since the start of RUN II. This large dataset provided good opportunities for meson spectroscopy studies at the Tevatron. This article will cover the recent new Υ(nS) polarization studies as well as exotic meson spectroscopy studies.
1257(2010); http://dx.doi.org/10.1063/1.3483450View Description Hide Description
The Tevatron at Fermilab continues to collect data at high luminosity resulting in datasets in excess of of integrated luminosity. The high collision energies allow for the observation of new heavy quark baryon states not currently accessible at any other facility. In addition to the ground state Lb, the spectroscopy and properties of the new heavy baryon states and as measured by the CDF and DO/ Collaborations will be presented.
1257(2010); http://dx.doi.org/10.1063/1.3483304View Description Hide Description
We review recent developments in strangeness photo‐ and electro‐ production off the proton and neutron, as investigated using CLAS in Hall B at Jefferson Lab. By measuring sufficient spin observables one can decompose the reaction mechanism into elementary amplitudes. We discuss progress toward this end in recent data from CLAS, including cross sections and spin observables. We next discuss new results on the mass distribution of the Λ(1405), which shows signs of being a composite meson‐baryon object of mixed isospin. The work on other hyperons such as the Ξ resonances will be mentioned, and future prospects for the CLAS program outlined.
1257(2010); http://dx.doi.org/10.1063/1.3483305View Description Hide Description
The P¯ANDA experiment (Pbar ANnihilations at DArmstadt) is a next generation hadron physics detector under design for the Facility for Antiproton and Ion Research (FAIR) at Darmstadt, Germany. It will be using cooled antiproton beams with an energy between 1.5 GeV and 15 GeV interacting with various internal targets.
The experiment is focusing on hadron spectroscopy, in particular the search for exotic states in the charmonium region, on the interaction of charm hadrons with the nuclear medium and on double‐hypernuclei.
With physics requiring precise partial wave analysis the experiment has almost 4π acceptance, a solenoid magnet for high tracks and a dipole magnet for the forward part of reaction products. A silicon vertex detector surrounds the interaction point. In both spectrometer parts tracking, charged particle identification, electromagnetic calorimetry and muon identification are available.
The experiment is being designed to fully exploit the extraordinary physics potential arising from the availability of high‐intensity, cooled antiproton beams.
Significant progress beyond the present understanding of the field is expected thanks to improvements in statistics and precision of the data.
1257(2010); http://dx.doi.org/10.1063/1.3483306View Description Hide Description
The GlueX detector facility in Hall‐D at Jefferson lab in Newport News is part of the 12 GeV upgrade and dedicated to the search for gluonic degrees of freedom in mesons by scattering high energy linearly polarized real photons of up to 9 GeV from nucleon targets. Civil construction of the Hall‐D complex has started as well as the construction of the various detector components. The current status of the project is outlined here.
1257(2010); http://dx.doi.org/10.1063/1.3483308View Description Hide Description
Hadron spectroscopy has been an essential part of the physics program with the CLAS detector in experimental Hall B at Jefferson Lab. Production of baryon and meson resonances with high energy (polarized) electron and photon beams was studied on a veriety of targets, ranging from hydrogen to lead. Physics topics of interest include: investigation of the spectrum of baryon and meson resonances, transition form‐factors, meson‐nucleon couplings (mesons in nuclei), and search for exotic and missing states. With the 12 GeV upgrade of the CEBAF machine, hadron spectroscopy in Hall B will be extended to a new domain of higher mass resonances and the range of higher transferred momentum using up to 11 GeV electron beams and the upgraded CLAS12 detector. In this paper a brief description of the CLAS12 detector and the physics program adopted for 12 GeV with emphasis to baryon and meson spectroscopy is presented.
1257(2010); http://dx.doi.org/10.1063/1.3483309View Description Hide Description
The Japan Proton Accelerator Research Complex, J‐PARC, has just finished its phase‐1 construction, and the proton beams have been delivered to the experimental facilities. The hadron experimental hall (Hadron Hall) is one of the experimental facilities at J‐PARC, where secondary beams such as pions and kaons, as well as the primary proton beams, will be used for fixed target experiments. The first proton beam to the Hadron Hall was delivered in January and February, 2009, and the beam was resumed from October. The first experiments at the Hadron Hall are just being started, at a low‐momentum beam lines for chaged partticle beams (K1.8BR and K1.8) and at a neutral kaon beam line. Other beam lines, such as K1.1 and high momentum beam lines, are planned. In this talk, physics topics to be conduced at the Hadron Hall will be introduced as well as the status and plan of the facility.
1257(2010); http://dx.doi.org/10.1063/1.3483310View Description Hide Description
Two proposals have been presented for the construction of super high luminosity B factories, the SuperB in Italy and SuperKEKB in Japan. We review the physics case for the construction of such facilities in the LHC era and highlight several topics of hadronic physics that can benefit from the high luminosity they will integrate. The present status of the accelerator and detector work toward the Technical Design Reports is also presented.
1257(2010); http://dx.doi.org/10.1063/1.3483311View Description Hide Description
In this talk we briefly review how the unitarization of Chiral Perturbation Theory with dispersion relations can successfully describe the meson‐meson scattering data and generate light resonances, whose mass, width and nature can be related to QCD parameters like quark masses and the number of colors.