Bulletin of the American Physical Society
4th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 59, Number 10
Tuesday–Saturday, October 7–11, 2014; Waikoloa, Hawaii
Session DJ: Ultrarelativistic Heavy Ions - Theory I |
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Chair: Gary Westfall, Michigan State University Room: Queen's 5 |
Thursday, October 9, 2014 9:00AM - 9:15AM |
DJ.00001: Collective dynamics in dijet+QGP-fluid system Yasuki Tachibana, Tetsufumi Hirano Compared with p+p collisions, dijet imbalance is enhanced in ultra-relativistic heavy-ion collisions as a consequence of jet quenching. Enhancement of low-$p_T$ particles distributed upto large angle from jet axes is observed by the CMS collaboration at LHC [1]. A large fraction of the di-jet momentum imbalance is compensated by these low-$p_T$ particles. On the other hand, according to recent results from the STAR collaboration, the dijet $p_T$-balance is restored by low-$pT$ particles closer to the jet direction at RHIC[2]. Motivated by these latest results, the dynamical transport process of energy and momentum deposited from jets traversing expanding QGP-fluid is studied. We perform simulations of dijet asymmetric events in ultra-relativistic heavy-ion collisions. By solving relativistic hydrodynamic equations with source terms in fully (3+1)-dimensional Milne coordinates, we describe the collective flow in dijet+QGP-fluid system. We calculate the $p_T$ distribution around dijet to interpret the events with large dijet imbalance both at LHC and at RHIC. \\[4pt] [1] Doga Gulhan [CMS Collaboration], talk at Quark Matter 2014. \\[0pt] [2] J\"orn Putschke [STAR Collaboration], talk at Quark Matter 2014. [Preview Abstract] |
Thursday, October 9, 2014 9:15AM - 9:30AM |
DJ.00002: Non-Gaussian source function for pions and kaons from a hydro+cascade model Hiromi Hinohara, Tetsufumi Hirano We study source functions for pions and kaons from a hybrid model in which event-by-event initial conditions, (3+1)-dimensional ideal hydrodynamics for evolution of the quark gluon plasma and hadronic cascade are combined. We derive the source functions, namely distribution of difference of last interaction points between two pions/kaons, by using this dynamical approach at the RHIC energy. We calculate one-dimensional source function for pions and kaons and compare them with the PHENIX data. Our results show the source function is largely deviated from the Gaussian as the PHENIX observed. We predict three-dimensional source functions which can be compared with experimental data from source imaging technique in the future experiments. We also discuss the azimuthal angle dependence of source functions in non-central collisions. [Preview Abstract] |
Thursday, October 9, 2014 9:30AM - 9:45AM |
DJ.00003: Derivation of the hydrodynamic equation from the quantum transport equation Yuta Kikuchi, Kyosuke Tsumura, Teiji Kunihiro The Kadanoff-Baym equation is the quantum transport equation which possesses the microscopic trans- port properties. We derive the hydrodynamic equation as an infrared effective dynamics of the microscopic theory from Kadanoff-Baym equation with the dynamical renormalization group method [1]. As a preparation, we check the validity of the dynamical renormalization group method developed in [2] by comparing with the Chapman-Enskog method discussed in [3]. We consider the unitary Fermi gas system as an example. Next, we derive the hydrodynamic equation including the quantum effect from the Kadanoff-Baym equation. Furthermore, we extend this method to the multi-component system. Finally, we apply the hydrodynamic equation derived here to the unitary Fermi gas system and analyze the transport coefficients of the second order hydrodynamics. \\[4pt] [1] D. Boyanovsky and H. J. de Vega, Annals Phys. 307 (2003) 335.\\[0pt] [2] K. Tsumura and T. Kunihiro, Eur. Phys. J. A 48, 162 (2012).\\[0pt] [3] Thomas Schaefer, arXiv:1404.6843. [Preview Abstract] |
Thursday, October 9, 2014 9:45AM - 10:00AM |
DJ.00004: Relativistic hydrodynamic equations and effective Lagrangian from quantum field theory Yoshimasa Hidaka, Tomoya Hayata, Masaru Hongo, Yuki Minami, Toshifumi Noumi We discuss dissipative relativistic hydrodynamic equations. Assuming a local Gibbs distribution as the initial one, we derive the relativistic hydrodynamics equations from quantum field theory. It is known that there is ambiguity of the choice of frames in the dissipative hydrodynamic equations. We frame-independently derive the first order equations, and discuss the frame dependence. We also derive the effective Lagrangian, and discuss the relation between our results and those in previous works that were phenomenologically derived. [Preview Abstract] |
Thursday, October 9, 2014 10:00AM - 10:15AM |
DJ.00005: Derivation of anomalous hydrodynamics from quantum field theory Masaru Hongo, Tomoya Hayata, Yoshimasa Hidaka, Yuki Minami, Toshifumi Noumi Hydrodynamics is a low-energy effective theory which describes a long-distance and long-time behavior of many-body systems. It has been recently pointed out that triangle anomalies affect macroscopic transport properties and generate anomaly-induced transports. These transport phenomena have a common feature that they are dissipationless, or in other words, they don't cause the entropy production. One example is the chiral magnetic effect, which represents the existence of a dissipationless vector current along the magnetic field and is expected to occur in ultra-relativistic heavy ion collisions. In this study, we derive anomalous hydrodynamic equations from the point of view of quantum field theory. Assuming the local Gibbs distribution at initial time, we derive a thermodynamic potential for relativistic hydrodynamics. This action has a form in the curved space-time whose metric is determined by the thermodynamic variables such as the temperature. We show that anomaly-induced transports manifest from this thermodynamic potential if systems do not have the parity symmetry, and, therefore, are dissipationless. We also discuss a relation between our work and other recent approaches that aim at deriving hydrodynamic equations for the parity-violating systems. [Preview Abstract] |
Thursday, October 9, 2014 10:15AM - 10:30AM |
DJ.00006: Fluctuation theorem in Bjorken expansion Ryuichi Kurita In the hot and dense QCD matter, quarks and gluons are deconfined to form Quark-Gluon Plasma(QGP). The QGP, which existed in the early universe, can be created experimentally by the relativistic heavy ion collisions at RHIC and LHC. The dynamics of the QGP in these experiments has been described by relativistic hydrodynamics. Towards detailed description of the QGP dynamics, event-by-event initial fluctuations have been included in the hydrodynamic model. In addition to these fluctuations, fluctuations originated from thermal noises during hydrodynamic evolution should be taken into account on an event-by-event basis. To investigate this hydrodynamic fluctuation, causal fluctuating hydrodynamics was formulated recently.\footnote{K. Murase and T. Hirano, arXiv:1304.3243} Applying this framework to the (0+1)-dimensional Bjorken expansion, we investigate how hydrodynamic noises cause entropy fluctuations. The probability of the events with entropy decreased and that with entropy increased are related through ``fluctuation theorem."\footnote{D. J. Evans and D. J. Sarles, \textbf{Phys. Rev. E} 52, 5839 (1995)} Through this theorem, we calculate the entropy fluctuation and claim that the thermal noise gets more important in the smaller systems such as p-A and peripheral A-A collisions. [Preview Abstract] |
Thursday, October 9, 2014 10:30AM - 10:45AM |
DJ.00007: Yet another instability in glasma Shoichiro Tsutsui, Hideaki Iida, Teiji Kunihiro, Akira Ohnishi In relativistic heavy ion collisions (HIC), hydrodynamic models can describe many experimental data and suggest that the quark-gluon plasma formed at RHIC and LHC is almost perfect fluid. We need very short thermalization time and far-from-equilibrium dynamics may be important in thermalization processes of HIC. In the earliest stages of HIC, classical gluon dynamics is dominant and many types of instabilities emerge there. These instabilities may strongly affect the later stages of dynamics; realization of chaoticity and field-particle conversions. We investigate instabilities of classical gluon fields under the homogeneous, but time dependent background color magnetic fields. The background field become periodic function of time and we can analyze the stability of fluctuations based on the Floquet theory which consists the basis of the Bloch theory. As a result, we get the complete structure of instability bands for physical degrees of freedom appearing from parametric resonance. We also find that the parametric instabilities considered here have different natures from the several known instabilities; Weibel and Nielsen-Olesen instabilities. We also discuss some implications of parametric resonance to the particle productions in HIC. [Preview Abstract] |
Thursday, October 9, 2014 10:45AM - 11:00AM |
DJ.00008: Husimi-Wehrl entropy in the quantum chaotic system -An efficient calculational method- Hidekazu Tsukiji, Hideaki Iida, Teiji Kunihiro, Akira Ohnishi, Toru T. Takahashi Early thermalization in heavy ion collisions still remains a theoretical challenge. It was suggested in the hydrodynamical analyses of the relativistic heavy-ion collisions at RHIC and later at LHC. There are many proposals for pinning down the underlying mechanism for it. Quantum fluctuations on top of the classical configurations (glasma) are found to induce instabilities. It may trigger the chaotic behavior of the gauge field and eventually give rise to entropy production. In this work, we investigate thermalization of glasma by using the Husimi-Wehrl entropy. Quasi-distribution function defined in phase space should be useful to describe possible chaotic behavior of a quantum system. We adopt the Husimi distribution function to discuss entropy production of quantum systems. Husimi function is a minimally coarse-grained Wigner function and semi-positive definite. As a first stage of the study, we calculate the Husimi-Wehrl (H-W) entropy of a quantum Yang-Mills system[Tsai, Muller(2012)] with two-degrees of freedom. We propose a Monte-Carlo method to numerically calculate the time evolution of the Husimi function and the H-W entropy. We also discuss an extension of the method to quantum field theories. [Preview Abstract] |
Thursday, October 9, 2014 11:00AM - 11:15AM |
DJ.00009: Properties of the baryon number distribution in QGP Keitaro Nagata, Kouji Kashiwa, Shinsuke Mochizuki-Nishigaki, Atsushi Nakamura We study properties of the baryon number distribution in QGP phase. We first point out that a Gaussian type of the canonical partition function with regard to the baryon number means the Roberge-Weiss phase transition. The canonical partition function of QCD at high temperatures is studied both analytically and numerically. We find that the canonical partition function obtained in lattice QCD simulation agrees with that obtained for Stefan-Boltzmann limit for T higher than Tc, and is the Gaussian function of the baryon number. [Preview Abstract] |
Thursday, October 9, 2014 11:15AM - 11:30AM |
DJ.00010: Non-Markov effect on the time evolution of higher order fluctuations of conserved charges Miki Sakaida, Masayuki Asakawa, Masakiyo Kitazawa Fluctuations of conserved charges in a given rapidity window are promising observables for extracting the properties of the QGP in heavy ion collisions. Recent experimental result on the rapidity window dependence of the net electric-charge fluctuation observed at LHC shows an interesting behavior that the value of the fluctuation does not reach their thermal equilibrium value. This result suggests that observed fluctuation contains information on the QGP. We investigate the time evolution of higher order fluctuations of conserved charges in the hadronic stage in heavy ion collisions. Previous study on the time evolution is modeled by the diffusion master equation, which describes a Markov process. However, diffusion on fluctuations of conserved charges in heavy ion collisions is non-Markov process. In the present study, we describe the time evolution of fluctuations of conserved charges with Kramers equation in order to include non-Markov property and investigate this effect on the rapidity window dependence of fluctuations of conserved charges. [Preview Abstract] |
Thursday, October 9, 2014 11:30AM - 11:45AM |
DJ.00011: Thermal interpretation of the proton number fluctuations in the beam-energy scan at RHIC/STAR Takahiro Sasaki, Kenji Fukushima We exposit an interpretation of the kurtosis and the skewness of the proton number fluctuation based on a thermal model. We demonstrate that the kurtosis decreases to show a significant deviation from the unity due to quantum statistics when the baryon density grows up. Such a simple estimate of the fluctuations in a thermal gas picture fits in with the experimental data of the beam-energy scan at RHIC/STAR. We also discuss effects from the nuclear matter region where the density dependent in-medium mass would further decrease the fluctuations. [Preview Abstract] |
Thursday, October 9, 2014 11:45AM - 12:00PM |
DJ.00012: D and D* meson mixing in magnetic field from QCD sum rules Kei Suzuki, Philipp Gubler, Koichi Hattori, Su Houng Lee, Sho Ozaki Quantum chromodynamics (QCD) in strong magnetic field is one of the most exciting topic in hadron physics. Especially, one can expect that hadrons are modified by strong magnetic fields such as that produced in ultrarelativistic heavy-ion collisions. In this study, we investigate the properties of the heavy-light (D) meson in magnetic field. QCD sum rule (QCDSR) is a method to investigate the properties of hadrons from QCD including non-perturbative effect. Recently, applications of QCDSR to systems in external magnetic field is tried by some authors. In this presentation, we report the result of the D meson mass shift in magnetic field from QCDSR and discuss mixing of the vector and pseudoscalar mesons by magnetic effect. [Preview Abstract] |
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