Proceedings of the 17th International Spin Physics Symposium
915(2007); http://dx.doi.org/10.1063/1.2750734View Description Hide Description
Polarization and spin effects are useful for probing the Standard Model, in both the electroweak sector and the strong sector, where the spin decomposition of the nucleon is still a hot topic, with important new data on the net polarizations of the gluon and the strange quarks. Spin phenomena are also useful in searches for new physics, for example via measurements of the anomalous magnetic moment of the muon and searches for electric dipole moments. The cross sections for the direct detection of dark matter may also have an important spin‐dependent component, related to the spin decomposition of the nucleon, that could be an important diagnostic tool. Polarization effects are also important diagnostic aids for high‐energy experiments at electron‐proton, proton‐proton and electron‐positron colliders.
915(2007); http://dx.doi.org/10.1063/1.2750735View Description Hide Description
The spin structure of the proton has been one of the most important quests driving high‐energy spin physics in recent years. In this talk, I review the status of theoretical studies in this area. I will also point out the future opportunities in understanding the proton spin.
915(2007); http://dx.doi.org/10.1063/1.2750736View Description Hide Description
The Relativistic Heavy Ion Collider (RHIC) is designed to provide collisions of high energy polarized protons for the quest of understanding the proton spin structure. Polarized proton collisions at a beam energy of 100 GeV have been achieved in RHIC since 2001. Recently, polarized proton beam was accelerated to 250 GeV in RHIC for the first time. Unlike accelerating unpolarized protons, the challenge for achieving high energy polarized protons is to fight the various mechanisms in an accelerator that can lead to partial or total polarization loss due to the interaction of the spin vector with the magnetic fields. We report on the progress of the RHIC polarized proton program. We also present the strategies of how to preserve the polarization through the entire acceleration chain, i.e. a 200 MeV linear accelerator, the Booster, the AGS and RHIC.
915(2007); http://dx.doi.org/10.1063/1.2750737View Description Hide Description
International Linear Collider, ILC, is a future energy‐frontier electron‐positron machine currently under design by a world‐wide collaboration. Utilizing the advantage of linear accelerator, a polarized electron beam plays an essential role for various key physics studies. In addition to the default operation‐mode, options are proposed such as polarized positron and polarized‐γγ collider mode. In this note, roles of the polarized beams are briefly discussed along the physics expected at ILC.
915(2007); http://dx.doi.org/10.1063/1.2750738View Description Hide Description
After briefly reviewing the status of the standard model, I will focus mainly on polarized electron scattering and other tests of the weak neutral current. I will also address other low energy tests in which polarization degrees of freedom play a crucial role, including precision muon physics and searches for electric dipole moments.
915(2007); http://dx.doi.org/10.1063/1.2750739View Description Hide Description
We present a review of recent works on variation of fundamental constants and violation of parity in atoms and nuclei.
Theories unifying gravity with other interactions suggest temporal and spatial variation of the fundamental “constants” in expanding Universe. The spatial variation can explain fine tuning of the fundamental constants which allows humans (and any life) to appear. We appeared in the area of the Universe where the values of the fundamental constants are consistent with our existence.
We describe recent works devoted to the variation of the fine structure constant α, strong interaction and fundamental masses (Higgs vacuum). There are some hints for the variation in quasar absorption spectra, Big Bang nucleosynthesis, and Oklo natural nuclear reactor data.
A very promising method to search for the variation consists in comparison of different atomic clocks. Huge enhancement of the variation effects happens in transitions between very close atomic and molecular energy levels. A new idea is to build a “nuclear” clock based on UV transition in Thorium nucleus. This may allow to improve sensitivity to the variation up to 10 orders of magnitude!
Measurements of violation of fundamental symmetries, parity (P) and time reversal (T), in atoms allows one to test unification theories in atomic experiments. We have developed an accurate method of many‐body calculations — all‐orders summation of dominating diagrams in residual e‐e interaction. To calculate QED radiative corrections to energy levels and electromagnetic amplitudes in many‐electron atoms and molecules we derived the “radiative potential” and the low‐energy theorem. This method is simple and can be easily incorporated into any many‐body theory approach. Using the radiative correction and many‐body calculations we obtained the PNC amplitude EPNC = −0.898(1 ± 0.5%) × 10−11 ieaB (−QW/N). From the measurements of the PNC amplitude we extracted the Cs weak charge QW = −72.66(29)exp(36)theor. The difference with the standard model value is .
915(2007); http://dx.doi.org/10.1063/1.2750740View Description Hide Description
Recent progress in the study of nuclear interactions has been discussed, focusing on experiments for few‐nucleon systems and for spin‐isospin excitations using intermediate‐energy beams. Some noticeable results are presented with emphasis on the data from RIKEN and RCNP, as well as future plans at these facilities.
915(2007); http://dx.doi.org/10.1063/1.2750741View Description Hide Description
Intermediate‐energy heavy‐ion collisions can produce a spin polarization of the projectile‐like species. Spin polarization has been observed for both nucleon removal and nucleon pickup processes. Qualitative agreement with measured spin polarization as a function of the momentum of the projectile‐like fragment is found in a kinematical model that considers conservation of linear and angular momentum and assumes peripheral interactions between the fast projectile and target. Improvements to the kinematical model are discussed that aim to achieve quantitative agreement with spin polarization data from both the nucleon removal and pickup processes.
915(2007); http://dx.doi.org/10.1063/1.2750742View Description Hide Description
Three subjects in hypernuclear physics related to hyperon spins in nuclei are discussed. The precision γ spectroscopy technique has been applied to various p‐shell hypernuclei and revealed spin dependence of ΛN interaction from experiments at KEK and BNL. It also provides a unique means to study g‐factor of a Λ in hypernuclei. The asymmetry of proton emission in non‐mesonic weak decay from a polarized Λ in a nucleus, which has recently been measured at KEK, disagreed with theoretical predictions of this process.
915(2007); http://dx.doi.org/10.1063/1.2750743View Description Hide Description
After a brief history of nucleon spin crisis I will motivate the need for a high energy polarized proton collider. I will then describe the distinct advantages of this new facility to study the spin structure of the proton. I will highlight the recent achievements of the RHIC Spin program from the experimental side, and review the achievements in terms of physics impact now and in near future.
915(2007); http://dx.doi.org/10.1063/1.2750744View Description Hide Description
The transverse spin phenomena are one of the most important topics being presently investigated in semi‐inclusive Deep Inelastic Scattering. In the last two years, since SPIN2004, many new data have become available. In parallel a remarkable progress in understanding the spin and the transverse momentum structure of the nucleon has occured.
915(2007); http://dx.doi.org/10.1063/1.2750746View Description Hide Description
This talk is dedicated to the memory of Jiro Kodaira who passed away in September, 2006. As one of his friends and also a collaborator from 1970’s I would like to talk about what contributions he has made to perturbative QCD, especially to Spin Physics.
915(2007); http://dx.doi.org/10.1063/1.2750747View Description Hide Description
Recent precise polarization measurements have considerably improved constraints on nucleon electromagnetic form factors. The BLAST experiment, carried out at MIT‐Bates Linear Accelerator Center, was designed to study these quantities systematically using the intense polarized stored electron beam of the South Hall Ring, highly polarized internal gas jet targets, and a symmetric toroidal spectrometer. Simultaneous measurements of multiple reaction channels with different combinations of beam and target polarizations were carried out to extract the nucleon form factors with high precision at Q 2< 1 GeV2/c2. Results for the nucleon form factors , , , and are presented and discussed.
915(2007); http://dx.doi.org/10.1063/1.2750748View Description Hide Description
A new generation of parity violating electron scattering measurements at high precision probe for physics beyond Standard Model. The experiments are complementary to high energy experiments and provide indirect access to TeV scale physics via electroweak one‐loop effects. Data are presented from the recently completed SLAC experiment E158, which measured the weak charge of the electron . The Qweak experiment at Jefferson Lab will measure the weak charge of the proton to an accuracy of ±4.3%.
915(2007); http://dx.doi.org/10.1063/1.2750749View Description Hide Description
The electron‐proton collider HERA is currently running with polarized electron or position beams, making it possible to perform electroweak analysis on deep inelastic scattering cross sections at large momentum transfer. Latest results from H1 and ZEUS experiments are described.
915(2007); http://dx.doi.org/10.1063/1.2750751View Description Hide Description
For few body systems, the treatment of charge symmetry breaking (CSB) that is based on meson‐exchange models is being replaced by effective field theories whose CSB originates in the down‐up quark mass difference and quark electromagnetic effects. In parallel, two new observations of CSB in π0 production (the fore‐aft asymmetry in n+p→d+π0 and the total cross section for d+d→4He+π0) provide applicable data.