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 EJ: MiniSymposium on FlowLike Observables in Heavy Ion Collisions 
Hide Abstracts 
Chair: Kyoichiro Ozawa , High Energy Research Institute, KEK Room: Queen's 5 
Thursday, October 9, 2014 7:00PM  7:30PM 
EJ.00001: Flow Measurements at the RHIC and LHC, What Have We Learned? What is Needed? Invited Speaker: Takahito Todoroki Higherorder flow coefficients, $v_n$, reflect the spacetime evolution process of hot and dense medium formed in relativistic heavy ion collisions. In the low $p_T$ region, experimental $v_n$ data at the highest energy A+A collisions at the RHIC and LHC is successfully described by various hydrodynamic calculations that employ Glauber/CGC initial conditions for heavy ion collisions and a shear viscosity of the medium. Our goal is to determine a single combination of an initial state and a viscosity value which can describe the data. However, there are currently more than one such combination and further constraints from experiments and theories are of importance. Azimuthal anisotropy $v_n$ is also observed in small collisions systems such as p(d)+A collisions at RHIC and LHC. The CGC (initial state effect) and hydrodynamic expansion (final state effect) are suggested as a possible explanations. Understanding the primary causes of $v_n$ evolution is important for the understanding of small collision systems and might provide useful information to the understanding of the initial condition in A+A collisions. In this talk, we will (i) summarize what we have observed in p(d)A and A+A collisions at the RHIC and LHC, and (ii) discuss what has to be done as next step towards more precise understanding of the properties of the medium. [Preview Abstract] 
Thursday, October 9, 2014 7:30PM  7:45PM 
EJ.00002: Chargedependent elliptic flow from eventbyevent anomalous hydrodynamic simulations Yuji Hirono, Hongo Masaru, Tetsufumi Hirano, Dmitri Kharzeev Macroscopic transport effects induced by the quantum anomaly have been attracting much attention. We develop an anomaloushydrodynamic model for heavyion collisions in order to quantify the effects of anomalous transports in the quarkgluon plasma. We perform eventbyevent simulations of the anomalous fluids, and we calculate the chargedependent particle distributions from subsequent hadronizations. According to the distributions, we calculate observables like chargedependent $v_2$ using the same methods as experimentalists use. We also take the initial fluctuations in chiral charge into account and see how they affect the final observables. [Preview Abstract] 
Thursday, October 9, 2014 7:45PM  8:00PM 
EJ.00003: Flow Measurements and selection of bodybody and tiptip enhanced samples in U+U collisions at STAR Hui Wang The azimuthal anisotropy of particle production is commonly used in highenergy nuclear collisions to study the early evolution of the system. The prolate shape of uranium nuclei provides the possibility to study how the initial geometry of the nuclei affects the azimuthal distributions. It also provides a unique opportunity to understand the initial conditions for particle production at midrapidity in heavy ion collisions. In this talk, the two and four particle cumulant, $v_2\{2\}$ and $v_2\{4\}$, from U+U collisions at $\sqrt{s_{NN}}=$ 193 GeV and Au+Au collisions at $\sqrt{s_{NN}}=$200 GeV for inclusive charged hadrons will be presented. The STAR Zero Degree Calorimeter is used to subdivide the 01\% centrality bin into even finer centralities. Differences were observed between the multiplicity dependence of $v_2\{2\}$ for most central Au+Au and U+U collisions. Data were compared with both Monte Carlo Glauber and IPGlasma models and it was seen that IPGlasma model does a better job of describing data. It has also been demonstrated that ZDC and multiplicity in combination provide a way to select bodybody or tiptip enhanced samples of central U+U collisions. We will also present preliminary $v_3\{2\}$ results for inclusive charged hadrons from Au+Au and U+U collisions. [Preview Abstract] 
Thursday, October 9, 2014 8:00PM  8:15PM 
EJ.00004: Charged hadron flow in Cu+Au collisions at RHICPHENIX Hiroshi Nakagomi Quark Gluon Plasma (QGP) was discovered in heavy ion collisions at RHIC. To investigate the characteristics of QGP, anisotropic flow plays an important role in study of QGP properties because it provides access to initial spacial anisotropy, density profile and shear viscosity over entropy ratio. In 2012, Cu+Au collisions, the first asymmetric collisions of heavy nuclei, were operated at RHIC. Measurement of flow in asymmetric collisions is a subject of special interest because they probe different density profiles, pressure gradients and initial triangularity comparing to symmetric collisions in midcentral collisions. In this talk we present current status of flow observables in Cu+Au 200 GeV collisions at PHENIX as a function of transverse momentum and (pseudo)rapidity. [Preview Abstract] 
Thursday, October 9, 2014 8:15PM  8:30PM 
EJ.00005: Production and Elliptic Flow of Dileptons and Photons in the semiQuark Gluon Plasma Robert Pisarski, Charles Gale, Yoshimasa Hidaka, Sangyong Jeon, Shu Lin, JeanFrancoise Paquet, Daisuke Satow, Vladimir Skokov, Gojko Vujanovic We consider the thermal production of dileptons and photons at temperatures above the critical temperature in QCD. In the semi Quark Gluon Plasma (QGP), color excitations are suppressed by a small value of the Polyakov loop. Comparing the semiQGP to the usual, perturbative QGP, we find a mild enhancement of thermal dileptons. In contrast, to leading logarithmic order in weak coupling there are far fewer photons from the semiQGP than the usual QGP. To illustrate the possible effects we use a hydrodynamic model. Dileptons uniformly exhibit a small elliptical flow, but the strong suppression of photons in the semiQGP tends to bias the elliptical flow of photons to that generated in the hadronic phase. [Preview Abstract] 

EJ.00006: ABSTRACT WITHDRAWN 
Thursday, October 9, 2014 8:45PM  9:00PM 
EJ.00007: Systemsize and beam energy dependence of the spacetime extent of the pion emission source Robert Pak Twopion interferometry measurements are used to extract the Gaussian source radii $R_{out}$, $R_{side}$ and $R_{long}$, of the pion emission sources produced in $d+$Au, Cu$+$Cu and Au$+$Au collisions for several beam collision energies at PHENIX experiment. The extracted radii, which are compared to recent STAR and ALICE data, show characteristic scaling patterns as a function of the initial transverse geometric size of the collision system, and the transverse mass of the emitted pion pairs. These scaling patterns indicate a linear dependence of $R_{side}$ on the initial transverse size, as well as a smaller freezeout size for the $d+$Au system. Mathematical combinations of the extracted radii generally associated with the emission source duration and expansion rate exhibit nonmonotonic behavior, suggesting a change in the expansion dynamics over this beam energy range. [Preview Abstract] 
Thursday, October 9, 2014 9:00PM  9:15PM 
EJ.00008: Forward and backward rapidity longrange correlation in pPb collisions at $\sqrt{s_{NN}}$=5.02 TeV with the ALICE detector Yuko Sekiguchi Measurements of the particle correlations are very useful to investigate the underlying mechanism and the dynamics of particle production in highenergy nucleusnucleus collisions. Long range, near side angular correlations have been observed in high multiplicity pp and pPb collisions at the LHC energy. Possible explanations of the long range correlations in high multiplicity pp and pPb collisions are the collective behavior of the created medium and/or the remnants of the strong color fields created by the dense gluonic field (gluon saturation). The saturation effects are expected to be enhanced at forward rapidity region and the measurements of the particle productions with large rapidity gaps and the centrality dependence are important to quantify saturation and hydrodynamical final state effects. The twoparticle correlations are measured with VZERO and TPC, where the ALICE VZERO detectors cover 3.7$ < \eta < $ 1.7 in backward and 2.8 $< \eta <$ 5.1 in forward. The status of the data analysis for pPb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV will be presented. [Preview Abstract] 
Thursday, October 9, 2014 9:15PM  9:30PM 
EJ.00009: A parametric study of dihadron azimuthal angular correlations in forward rapidity protonnucleus collisions at RHIC and the LHC Jamal JalilianMarian, Elena Petreska We investigate the behavior of dihadron azimuthal angular correlations in high energy protonnucleus collisions at RHIC and the LHC in the forward rapidity region. We consider the correlations in different kinematics separated by the saturation scale of the nucleus and study the dependence of the correlations on the transverse momenta of the hadrons as compared to the nuclear saturation scale. We then investigate the effect of the recently proposed quartic terms in the action on the angular correlation. [Preview Abstract] 
Thursday, October 9, 2014 9:30PM  9:45PM 
EJ.00010: Transverse dynamics of multistrange hadrons Shiori Takeuchi, Koichi Murase, Tetsufumi Hirano, Pasi Houvinen, Yasushi Nara We study the hadronic rescattering effects, in particular for multistrange hadrons, on the final observables within an integrated dynamical approach in which a (3+1)D ideal hydrodynamic model is combined with hadronic cascade model, JAM. Since the measured observables contain all the information throughout the spacetime evolution in relativistic heavy ion collisions, dissipation caused by hadronic rescattering in the late stage must be taken into account to investigate the properties of the quark gluon plasma. By comparing final observables to those obtained just after the QGP stage in this approach, we quantify the hadronic rescattering effects on particle ratio, azimuthal anisotropic flow $v_n$ and mean transverse momentum $\langle p_{\mathrm T} \rangle$. Furthermore we show that multistrange hadrons can be direct probes of the QGP at hadronization due to a fact that multistrange hadrons rescatter less than nonstrange hadrons. [Preview Abstract] 
Thursday, October 9, 2014 9:45PM  10:00PM 
EJ.00011: Effects of causal hydrodynamic fluctuations on observables in relativistic heavyion collisions Koichi Murase, Tetsufumi Hirano In recent years, the flow harmonics $v_n$ are systematically observed in relativistic heavyion collision experiments at RHIC and LHC, and attract a lot of theoretical and experimental interests. Initial state fluctuations turned out to be important to explain these flow harmonics through eventbyevent numerical calculations. While, there are other sources of fluctuations such as hydrodynamic fluctuations which are thermal fluctuations of hydrodynamics, and they have effects on the flow harmonics and other observables in the same matter as the initial fluctuations. We implement (3+1)dimensional relativistic fluctuating hydrodynamics, which is viscous hydrodynamics with causal hydrodynamic fluctuations [1], in our dynamical models. We then investigate the effect of the hydrodynamic fluctuations on observables such as flow harmonics, and compare the effect with that of the initial fluctuations. \\[4pt] [1] Koichi Murase, Tetsufumi Hirano, arXiv:1304.3243 [nuclth] [Preview Abstract] 
Thursday, October 9, 2014 10:00PM  10:15PM 
EJ.00012: Simulation of causal hydrodynamic fluctuation in Bjorken expansion Kenichi Nagai, Ryuichi Kurita, Koichi Murase, Tetsufumi Hirano We investigate the effects of causal hydrodynamic fluctuation [1] on dynamics of the quark gluon plasma (QGP) in the Bjorken expansion model [2]. The QGP is created in relativistic heavy ion collisions and its time evolution can be described by relativistic hydrodynamics. So far the effects of eventbyevent (ebye) initial fluctuation on final flow observables have been focused. In addition to these effects, fluctuation during hydrodynamic evolution should be also important on an ebye basis of hydrodynamic description of the QGP. We first introduce causal hydrodynamic fluctuation into the Bjorken expansion model. We then perform simulations of this Bjorken model with hydrodynamic fluctuation on an ebye basis. We find the final entropy fluctuates around the mean value. This indicates multiplicity also fluctuates due to hydrodynamic fluctuation and can contain transport properties of the QGP. This effect would be significant in small system such as pA and peripheral AA collisions. \\[4pt] [1] K. Murase and T. Hirano, arXiv:1304.3243.\\[0pt] [2] J.D. Bjorken, Phys. Rev. D 27, 140 (1983). [Preview Abstract] 
Follow Us 
Engage
Become an APS Member 
My APS
Renew Membership 
Information for 
About APSThe American Physical Society (APS) is a nonprofit membership organization working to advance the knowledge of physics. 
© 2021 American Physical Society
 All rights reserved  Terms of Use
 Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 207403844
(301) 2093200
Editorial Office
1 Research Road, Ridge, NY 119612701
(631) 5914000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 200452001
(202) 6628700