Bulletin of the American Physical Society
APS April Meeting 2014
Volume 59, Number 5
Saturday–Tuesday, April 5–8, 2014; Savannah, Georgia
Session B6: Relativistic Heavy Ions: Theoretical Aspects |
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Sponsoring Units: DNP Chair: Vivian Incera, University of Texas at El Paso Room: 200 |
Saturday, April 5, 2014 10:45AM - 10:57AM |
B6.00001: Thermal fluctuations in heavy-ion collisions Clint Young The thermal fluctuations inherent in viscous hydrodynamics are significant when examining a fluid either at small length scales or near a critical point. Both of these conditions can be met in ultra-relativistic heavy-ion collisions. These fluctuations have small but non-vanishing effects on two-particle correlations at the Relativistic Heavy-Ion Collider (RHIC) and at the Large Hadron Collider (LHC). Because the amplitudes of the fluctuations are related to viscosity through the fluctuation-dissipation relation, their effects on observables may lead to an independent measurement of the transport coefficients in quark-gluon plasma. [Preview Abstract] |
Saturday, April 5, 2014 10:57AM - 11:09AM |
B6.00002: Reconsideration of Statistical Hadronization in Light of LHC Results Michal Petran, Johann Rafelski We revisit the description of hadron production in heavy-ion collisions at SPS, RHIC considering new insights gained from LHC particle multiplicity analysis~[1]. For all but lowest SPS energy just like at LHC, the non-equilibrium statistical hadronization model describes the experimental results accurately with a freeze-out temperature of $T\simeq140\,{\rm MeV}$ and light quark phase space occupancy $\gamma_q\simeq 1.6$. A remarkable result is the constant hadronization pressure across SPS, RHIC, and LHC of $P = 80\pm 3\,\mathrm{MeV/fm}^3$. On the other hand we find that the QGP fireballs created at different collision energies and centralities differ in size of hadronization volume by over two orders of magnitude, and analysis covers a wide range of chemical potential $\mu_B<600$ MeV. The considerable difference between two lowest energies studied at SPS: $\sqrt{s_{NN}}=6.26$ and $7.61$ GeV indicates an opportunity for the Beam Energy Scan program at RHIC to identify the onset of quark deconfinement via study of hadron multiplicity yields. [Preview Abstract] |
Saturday, April 5, 2014 11:09AM - 11:21AM |
B6.00003: Time-Dependent Dynamics of Massive Quarkonium Resonances in Nuclear and Quark-Gluon-Plasma Media Noor Sabrina Mah Hussin, Asmaa Shalaby, Athanasios Petridis The time-dependent Schr\"odinger equation is used to study the formation of quarkonia and their propagation in Quark-Gluon Plasma (QGP) and nuclear media. The initial bound (ground) state is computed using imaginary-time propagation in a confining potential. The QGP is simulated with a confining potential of an extended asymptotic freedom region. The initial state propagates through this potential in real time. The nuclear medium is simulated with a periodic potential. In all cases the survival probability is calculated versus time for various potential parameters and relative momenta of the quarkonium with respect to the surrounding medium. In all calculations the staggered-leap frog method is used with special attention paid to the issue of stability. It is found that quarkonium decay is typically non-exponential. Fast moving states decay faster. There is a distinctive difference in the time-dependence of the survival probability between QGP and the nuclear medium. The effects of more realistic potentials are investigated. [Preview Abstract] |
Saturday, April 5, 2014 11:21AM - 11:33AM |
B6.00004: Enhanced Pair Production in Multicenter Systems by SuperIntense Lasers Andre Bandrauk Electron-positron(e-e$+)$ pair production is considered for many-center systems with multiple bare nuclei immersed in intense static electric fields corresponding to the extrema of electric fields planned by future super intense laser pulse sources with intensities I\textgreater 10$^{24}$ W/cm$^{2}$. It is shown analytically using an exactly solvable 1-D delta potential model [1] in a multicenter Dirac equation that there are two distinct regimes where pair production rates are enhanced.At small internuclear distances, the effective nuclear charge approaches the critical charge where the ground state dives into the negative continuum of the Dirac equation.At large atomic distances a new mechanism is predicted,similar to Charge Resonance Enhanced Ionization of molecules by intense, I $\sim$ 10$^{24}$ W/cm$^2$, laser pulses [2]. Multicenter resonances from the negative energy states are shown to cross into the positive energy states due to large field induced Stark shifts thus resulting in a resonantly enhanced pair production mechanism. A numerical method is developed to calculate the pair production rates from the multicenter Dirac equation. The latter is evaluated for systems (clusters) up to five nuclei of large charge. It is shown that the pair production rate for multicenter systems in superintense electric fields generally exceeds by orders of magnitudes the Schwinger tunneling rate which requires intensities of $\sim$ 10$^{29}$ W''/cm$^2$. [1] F Fillion-Gourdeau, E Lorin, A D Bandrauk, Phys Rev Lett 110,013002(2013); J Phys B 46,175002 (2013). [2] A D Bandrauk,F Legare, in ``Progress in Ultrafast Intense Laser Science'', VIII, edit K Yamanouchi et al,(Springer, Berlin, 2012) p 29-46. [Preview Abstract] |
Saturday, April 5, 2014 11:33AM - 11:45AM |
B6.00005: Towards the Test of Saturation Physics Beyond Leading Logarithm David Zaslavsky, Anna Stasto, Bo-Wen Xiao Earlier this year, we published the first numerical calculation to incorporate all next-to-leading order (NLO) corrections for the forward pion production cross section in pA collisions. Our calculation gives a good description of existing results from RHIC at $p_\perp$ up to the saturation scale. I will present an overview of the calculation, review the results for RHIC as compared to the experimental data, and present our predictions for the LHC's heavy ion program. I'll also discuss an interesting issue in which, at larger $p_\perp > Q_s$, the results of the prediction become negative, and review the progress of our attempts to cure the negativity by resumming higher-order terms of the cross section. [Preview Abstract] |
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