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 1WH: Workshop on the Expanding Future of High Energy Nuclear Physics at LHC and RHIC I |
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Chair: Xin-Nian Wang, LBNL Room: Kings 3 |
Tuesday, October 13, 2009 9:00AM - 9:30AM |
1WH.00001: Relativistic Heavy Ion Theory: Present and Future Invited Speaker: The success of theories, hydrodynamic models, recombination models, jet quenching and color glass condensate and so on brought us the fact that the strongly coupled quark-gluon plasma is created at RHIC. Now more detailed investigations from the theoretical side are carried out to know this hot and dense QCD matter at RHIC. I will give a brief overview on recent theoretical achievements for understanding of RHIC physics and also outline interesting topics which arise from recent experimental results and still await a theoretical explanation. I will discuss the expected future of the LHC physics from the point of view of exploration of the QCD phase diagram. [Preview Abstract] |
Tuesday, October 13, 2009 9:30AM - 10:00AM |
1WH.00002: The present status and future physics program of RHIC Invited Speaker: RHIC is preparing to enter its second decade of operations. I will highlight several measurements from the first 10 years of running that have been pivotal in our belief that the hot and dense matter created in AA collisions at RHIC is strongly interacting, has partonic degrees of freedom, flows like a near-perfect fluid, and is highly opaque to high energy partons passing through it. I will then discuss the near-future heavy-ion program at RHIC. It is focussed on extended top energy Au-Au running and a systematic low energy beam scan. The goals of the 200 GeV collision runs are the detailed measurements of heavy-flavor (c and b) production and jet reconstruction. These results will greatly improve our understanding of the properties of the medium created. The purpose of the low energy beam scan is to search for the QCD critical point. Finally, there are also plans to study U+U collisions where interesting effects may be observed due to the highly oblate nature of the U nucleus. [Preview Abstract] |
Tuesday, October 13, 2009 10:00AM - 10:30AM |
1WH.00003: Jet shapes and jet cross sections in relativistic heavy-ion collisions Invited Speaker: Energetic partons traversing a hot/dense nuclear medium are expected to lose a large fraction of their energy. In fact, the stopping power of strongly-interacting matter for color-charged particles has, by far, the largest experimentally established effect: the attenuation of the cross section for final-state observables of large mass/momentum/energy. This jet quenching mechanism has been used to successfully explain the strong suppression of the hadron spectra at large transverse momentum observed in nucleus-nucleus collisions at the Relativistic Heavy Ion Collider (RHIC). However, at present, most measurements of hard processes are limited to single particles and particle correlations, which are only the leading fragments of a jet. Experimental advances at RHIC and new opportunities provided by LHC will allow for innovative and much more definitive tests of the mechanisms of parton attenuation in matter. In this study we demonstrate that jet shape and jet cross section measurements are precisely the tools to probe the underlying QCD theory. We present a first step in understanding these shapes and cross sections in heavy ion reactions. Our approach allows for detailed simulations of the experimental acceptance/cuts that help isolate jets in such high-multiplicity environment. It is demonstrated for the first time that the pattern of stimulated gluon emission can be correlated with a variable quenching of the jet rates and provide an approximately model-independent approach to determining the characteristics of the medium-induced bremsstrahlung spectrum. Surprisingly, in realistic simulations of parton propagation through the QGP we find a minimal increase in the mean jet radius even for large jet attenuation. Jet broadening is manifest in the tails of the energy distribution away from the jet axis and its qualification may need high statistics measurements. [Preview Abstract] |
Tuesday, October 13, 2009 10:30AM - 11:00AM |
1WH.00004: COFFEE BREAK
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Tuesday, October 13, 2009 11:00AM - 11:30AM |
1WH.00005: Full jet-reconstruction in heavy-ion collisions at RHIC Invited Speaker: Measurements of inclusive hadron suppression and di-hadron azimuthal correlations in ultra-relativistic nuclear collisions have provided important insights into jet quenching in hot QCD matter, but are limited in their sensitivity due to well-known biases. Complete jet reconstruction in heavy-ion collisions would provide a direct measurement of the energy of the scattered parton before energy loss, alleviating such biases and allowing a measurement of the energy loss probability distribution necessary to extract properties of the medium in a model-independent way from hard probes. In this talk measurements of the inclusive jet spectrum and the fragmentation function of fully reconstructed jets in 200 GeV heavy ion collisions will be presented. The fragmentation function as well as the jet spectra in heavy ion collisions will be presented and discussed with respect to p+p reference measurements. [Preview Abstract] |
Tuesday, October 13, 2009 11:30AM - 12:00PM |
1WH.00006: Direct Photon-Hadron Correlations in RHIC Collisions Invited Speaker: Direct photon-hadron correlations from photon-jet pairs are an important tool to study jet energy loss and jet modification in Heavy Ion collisions since the direct photon escapes the medium without strong interaction and can act as a control or energy calibrator to the opposing jet in the same event. Due to the large background of meson decay photons from di-jets, measurements are experimentally difficult, and further complications in interpretations arise from Bremmstrahlung-like fragmentation photons also associated with di-jets. First measurements of direct photon-jet correlations have been performed by both PHENIX and STAR. Implications of these results and the status of future improvements will be discussed. [Preview Abstract] |
Tuesday, October 13, 2009 12:00PM - 12:30PM |
1WH.00007: Heavy Quarkonia Production in High Energy Heavy Ion Collisions at RHIC and Perspectives for the LHC Invited Speaker: High energy heavy ion collisions has been performed at RHIC to search for the new state of QCD matter and to study its proerties. Quarkonia ($J/\psi$, $\psi^{\prime}$, $\chi_{c}$, $\Upsilon$) have long been considered as one of the most promising probes for the deconfinment of the hot and dense QCD matter, since the attraction between heavy quark and anti-quark pairs is predicted to be reduced in the medium due to the color screening. Quarkonia production has been measured in $p+p$, $d$+Au, Cu+Cu and Au+Au collisions at RHIC to understand the production process, the cold nuclear matter effects that modify the quarkonia production in nuclear environment as well, and the hot and dense medium effects such as color screening, thermal gluon dissociation, and regeneration of quarkonia from uncorrelated heavy $q\bar{q}$ pairs. Recent experimental and theoretial progress to understand the observed $J/\psi$ suppression at RHIC will be present, issues for the future quarkonia measurement at RHIC and perspectives for the upcoming LHC will be present in this talk. [Preview Abstract] |
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