Bulletin of the American Physical Society
3rd Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 54, Number 10
Tuesday–Saturday, October 13–17, 2009; Waikoloa, Hawaii
Session 1WG: Workshop on Investigations of Glue and the Physics and Prospects of the Electron Ion Collider |
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Chair: Yoshiyuki Miyachi, Tokyo Tech Room: Kings 2 |
Tuesday, October 13, 2009 9:00AM - 9:30AM |
1WG.00001: What we have learned from the RHIC d+Au program Invited Speaker: Measurements in p+A, and at RHIC in d+Au collisions have long been a fundamental arena for the study of the modification of QCD processes in normal or cold nuclear matter (CNM). They provide insight into fundamental physics such as coherence effects or shadowing in nuclei, the saturation of gluons at small momentum, the energy loss of quarks or gluons in CNM, and soft multiple scattering effects that cause broadening of the transverse momentum. For heavy-ion physics it has been apparent for some time that CNM effects must be quantified before physics beyond these can be inferred from the heavy-ion results. Most notably at RHIC, the large densities of the hot-dense matter created in heavy-ion collisions indicated by the suppression of pions at high transverse momentum, could not be substantiated until it was verified that no such effects occured in d+Au collisions. We will review the progress at RHIC in quantifying CNM effects in various sectors including high-pT particle suppression and correlations, direct photon production, particle production at forward rapidity and small x, and open and closed heavy-quark systems - in the context of related measurements at Fermilab and CERN. [Preview Abstract] |
Tuesday, October 13, 2009 9:30AM - 10:00AM |
1WG.00002: RHIC-spin program for the next several years Invited Speaker: It has been almost a decade since RHIC provided the first polarized proton proton collision. The performance is improving towards the design luminosity and polarization. With the applicability of the factorized perturbative QCD (pQCD) and gluons in a leading order process, RHIC is a unique place to access to the gluon spin in the proton. In the first stage, PHENIX and STAR measured the double helicity asymmetries of inclusive channels. The data excluded the large gluon polarization scenario and prefers rather small polarization in the range of Bjorken-x presently measured. The next step is to study the x dependence. One way is to fix the kinematics, and the other is to change the collision energy to enlarge the x-coverage. The inclusion of data with lower collision energy than the nominal RHIC energy ($\sqrt{s}$=200GeV) might be an option if the range where the factorized pQCD can be applied is extended. The field of transverse spin physics is rapidly growing. PHENIX and STAR spent a half of their beam time taking data with transverse beam polarization. BRAHMS used its great capability of particle ID and its broad rapidity coverage to measure single spin asymmetries. At this stage, it is important to collect many experimental evidences in wide range of kinematics and channels. For this purpose, STAR recently extended their forward acceptance. With the full energy ($\sqrt{s}$=500GeV), W boson has a reasonable production rate. Thanks to its parity violating process, it provides a unique way to separate the flavor spin components with the high scale of $\rm{Q}^2$ ($\sim 6400\rm{GeV}^2$) and no fragmentation involved. In 2009, RHIC provided the first 500GeV polarized collisions successfully. Experiments demonstrated the feasibility of this program. In this talk, I will give a short summary of what we have learned from the past RHIC runs and prospects for the near future measurements. [Preview Abstract] |
Tuesday, October 13, 2009 10:00AM - 10:30AM |
1WG.00003: Physics Program with 12 GeV JLab Invited Speaker: Jefferson Lab (JLab) is one of the premier facilities in nuclear and hadronic physics in the world. Recommended as the top priority in the most recent US nuclear physics long-range plan [1], JLab is undergoing an energy upgrade from 6 GeV to 12 GeV [2]. With high luminosity and high polarization CW electron beam, the 6 GeV physics program has produced exciting results in the last decade. The energy upgrade will greatly expand the JLab capability and open up new opportunities. The planned physics program will be discussed, including a precision study of valence quark distributions, a 3-d mapping of the transverse momentum dependent distributions and the generalized parton distributions, low-energy tests of the standard model, a search for exotic mesons and a study of few-body and nuclear medium effects. \\[4pt] [1] The Frontiers of Nuclear Science: A Long Range Plan.(Dec. 2007)\\[0pt] [2] http://www.jlab.org/12GeV/ [Preview Abstract] |
Tuesday, October 13, 2009 10:30AM - 11:00AM |
1WG.00004: COFFEE BREAK
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Tuesday, October 13, 2009 11:00AM - 11:30AM |
1WG.00005: The nucleon structure, what an Electron-Ion Collider will teach us Invited Speaker: The question after the individual parton (quarks and gluons) contributions to the spin of the nucleon is even after 20 years of experimental efforts not yet solved. After several precise measurements in polarized deep inelastic scattering it is clear, that the spin of the nucleon cannot be explained by the contribution of the quarks alone. This is affirmed by the newest results from COMPASS, HERMES and JLAB on the inclusive spin structure function g$_1$ and on the individual contributions from the different quark flavors from semi-inclusive deep inelastic scattering data. Recent measurements from the polarized proton proton collider RHIC show that also the contribution from the Gluons is smaller than originally expected. Recent clear experimental evidence of exclusive reactions, especially DVCS, allows in the formalism of generalized parton distributions the study of an other component of the nucleon spin the orbital angular momentum. The most recent results on indications of the size of the orbital angular momentum of quarks from data and lattice measurements indicate also here small contributions from quark orbital angular momenta to the spin of the proton. At the electron-ion collider (EIC) it will not only be possible to measure all these contributions to the spin of the nucleon with unseen precision, but more importantly the range of all observables can be extended to much smaller Bjoerken $x$ (~10$^{-4}$). This will allow removing the biggest uncertainty in all these observables the extrapolation to the currently unmeasured low-x region. The study of the spin structure is only one of the observables sensitive to the nucleon structure, which can be studied at the EIC. The possibility to run heavy nuclei will give the possibility to study the transition from the structure of a nucleon to nuclei. Several measurements giving a handle on the modifications of the partonic structure of nucleons in nuclei will be presented. [Preview Abstract] |
Tuesday, October 13, 2009 11:30AM - 12:00PM |
1WG.00006: How universal gluodynamics underlying the structure of matter can be uncovered with precision by an Electron-Ion Collider (EIC) Invited Speaker: We discuss measurements in DIS off nuclei at an EIC that provide unique insight into the nature of strong color fields in QCD. We will focus in particular on what one can learn from diffractive DIS measurements that will be performed for the first time at an EIC. [Preview Abstract] |
Tuesday, October 13, 2009 12:00PM - 12:30PM |
1WG.00007: Planning and Realization of an Electron Ion Collider Invited Speaker: According to the 2007 Nuclear Physics Long Range Plan, ``An EIC with polarized beams has been embraced by the U.S. nuclear science community as embodying the vision for reaching the next QCD frontier.'' I will discuss the open questions of science, technology and strategy that are being addressed in order to convince the community to endorse a high priority for construction of such a facility in the next Long Range Plan. Both Brookhaven National Laboratory and Jefferson Lab have designs built upon their present facilities to achieve eventually an EIC with polarized electron beams up to 10-20 GeV colliding with polarized proton beams up to 250 GeV and with beams of heavy nuclei up to 100 GeV/nucleon. Both designs have introduced staging options that would achieve lower collision energies at a fraction of the full cost. I will discuss the science reach of an EIC as a function of its energy and luminosity goals, initial rough cost estimates for various designs, and the accelerator and detector research and development being launched to demonstrate technical feasibility of the ambitious design goals. I will also place these plans in the broader context of international discussions of possible electron-hadron colliders of both much lower and much higher energy. [Preview Abstract] |
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