Bulletin of the American Physical Society
2007 Annual Meeting of the Division of Nuclear Physics
Volume 52, Number 10
Wednesday–Saturday, October 10–13, 2007; Newport News, Virginia
Session HA: AdS/CFT - Applications of String Theory to Nuclear Physics |
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Chair: Alice Mignerey, University of Maryland Room: Newport News Marriott at City Center Grand Salon I |
Saturday, October 13, 2007 9:00AM - 9:36AM |
HA.00001: Bulk Properties and Collective Flow of Quark Gluon Plasma Invited Speaker: Quantum Chromodynamics predicts a transition from a hadronic phase at temperatures less than 150-200 MeV to a quark gluon plasma phase at higher temperatures. Lattice calculations show a big increase in the entropy density in this vicinity. Whether the transition is first or second order or a smooth rapid crossover depends upon the values of the up, down and strange quark masses. The goal of the heavy ion experimental program at RHIC is to observe this transition and to study the nature of the quark gluon plasma quantitatively. Two big surprises arose from these experiments: Substantial collective flow has been observed, as evidenced by single-particle transverse momentum distributions and by azimuthal correlations among the produced particles, and the degree to which high energy jets are attenuated in the produced matter. A variety of theoretical models of these collisions require initial energy densities more than a factor of 10 greater than in neutron star cores and more than a factor of 100 greater than within atomic nuclei. Taken together this body of work implies a strongly interacting phase of quarks and gluons beyond the capabilities of perturbation theory. This has motivated approaches based on gauge theories with gravity duals where physical observables may be calculated in a strong coupling limit. This in turn has stimulated interest from members of the string theory community who are currently bringing their expertise to bear on the problem. [Preview Abstract] |
Saturday, October 13, 2007 9:36AM - 10:12AM |
HA.00002: Quark Gluon Plasma: Experiments With Strings Attached? Invited Speaker: Experiments have shown that the hot partonic matter formed in heavy ion collisions at RHIC has substantial collective flow and is highly opaque to energetic quarks and gluons. New measurements of strange quarks, energetic jets, and rare particles containing heavy quarks are beginning to shed light on properties of this novel plasma. Constraints on the viscosity per unit entropy, timescales for thermalization and build-up of collective motion, diffusion of heavy quarks, the response of the medium to deposited energy, and perhaps even the speed of sound in the plasma are now becoming experimentally accessible. The new data have inspired novel approaches to calculating the properties of quantum systems in the strong coupling limit. [Preview Abstract] |
Saturday, October 13, 2007 10:12AM - 10:48AM |
HA.00003: Understanding the Quark-gluon Plasma via String Theory Invited Speaker: Collisions of high-energy gold nuclei at the Relativistic Heavy Ion Collider (RHIC) in Brookhaven National Laboratory create exploding droplets of quark-gluon plasma, the stuff which filled the universe microseconds after the Big Bang. The quark- gluon plasma at RHIC exhibits many surprising properties: it is close to an ideal liquid and it strongly attenuates the high energy quarks trying to plow through it. So far calculations in QCD have not been able to explain these properties satisfactorily, but interesting insight has been gained by using techniques from string theory. In the last ten years string theory has revealed a surprising and deep connection between quantum gravity and non-Abelian gauge theories similar to QCD. Such a connection enables one to answer difficult questions in some strongly coupled gauge theories by simple calculations of classical gravity. I will discuss some examples where these string theory techniques have been used to shed light on existing data from RHIC and to make one prediction that can be tested by experiments in the near future. [Preview Abstract] |
Saturday, October 13, 2007 10:48AM - 11:24AM |
HA.00004: A few comparisons between string theory and heavy-ion physics Invited Speaker: String theory---in particular, the gauge-string duality---provides a window into the physics of strongly coupled gauge theories which may be of use in understanding aspects of relativistic heavy ion collisions. Although the supersymmetric gauge theories we understand most clearly via string theory are not QCD, their behavior at finite temperature seems to be similar enough to the deconfined quark-gluon plasma to make meaningful comparisons. Interesting comparisons include thermalization time, energy loss by heavy quarks, and the formation of sonic booms. Momentum diffusion by heavy quarks raises some intriguing puzzles. The string theory computations all hinge on the dynamics of black horizons in a fifth dimension used to characterize energy scales. Although such horizons may seem fanciful, they in fact provide very practical and direct tools for computing dynamical properties of analogs of the quark-gluon plasma. The overall picture is that a few string theory predictions are suggestively close to experimentally favored values, but non-trivial barriers remain to making the predictions more precise. [Preview Abstract] |
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