Strangeness in Quark Matter

21 Jul 2013, 08:30 → 27 Jul 2013, 13:00 GB

The University of Birmingham

David Evans (University of Birmingham (GB)), Orlando Villalobos Baillie (University of Birmingham (GB))

The 14th International Conference on Strangeness in Quark Matter.

Topics include:

• Strangeness and heavy quark production in nuclear collisions and hadronic interactions.
• Bulk matter phenomena associated with strange and heavy quarks.
• Strangeness in astrophysics
• Open questions and new developments

Sunday, 21 July

Welcome Reception + Registration

Monday, 22 July

Registration

Opening talks

1 Welcome and VC Address

Slides SQM2013Welcome.pdf SQM2013Welcome.pptx

2 A Snapshot of our Experimental Knowledge Circa Winter 2012-13

Speaker: Helen Louise Caines (Yale University (US))

Slides SQMCaines.pdf

3 Strangeness in Quark Matter: Opening Talk

Speaker: Marcus Bleicher (Uni Frankfurt)

Paper Proceedings_sqm_bleicher_2014_02_13.pdf

11:10 Break

Plenary 1

Convener: Tamas Biro (KFKI RMKI)

4 Strangeness overview Experiment

Speaker: Boris Hippolyte (Institut Pluridisciplinaire Hubert Curien (FR))

Slides (.key) B_Hippolyte_SQM_2013_vf.key

Slides (.pdf) B_Hippolyte_SQM_2013_vf.pdf

5 Strangeness overview Theory

Speaker: Francesco Becattini (Unversity of Florence)

Slides becattini.pdf

Plenary 2

Convener: Andrea Dainese (Universita e INFN (IT))

6 Overview of results from ALICE

Speaker: Mateusz Ploskon (Lawrence Berkeley National Lab. (US))

Slides SQM-MPloskon-v2.4.pdf

7 Recent Results on Strangeness Production at STAR

Strange hadron productions are sensitive probes to the dynamics of the hot and dense matter created in heavy-ion collisions. In this talk, we will present the recent STAR measurements on the production of various strange hadrons (K0s, phi, Lambda, Xi and Omega) in $\sqrt{S_{NN}}$ = 7.7 - 39 GeV Au+Au collisions in the STAR beam energy scan program. We will investigate the collision energy dependence of the strangeness enhancement, nuclear modification factors, baryon to meson ratios, as well as the phi meson elliptic flow. We will present the extracted chemical and kinetic freeze-out parameters with the thermal and blast wave models as a function of energy and centrality. The physics implications of these measurements on the collision dynamics will be discussed.

Speaker: Xianglei Zhu (Tsinghua University)

Slides zhu_sqm2013_v9.pdf

8 Identified charged hadron spectra and ratios in PHENIX

PHENIX has recently reported[arXiv:1304.3410] measurements of identified charged hadron spectra and ratios in Au+Au and d+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. Identified hadrons are an important probe of both hot and cold nuclear matter. The intermediate $p_T$ region, 2 -5~GeV/c, is of particular interest. In Au+Au collisions, the production of mesons is suppressed in this $p_T$ region relative to that in p+p collisions, while the production of baryons is nearly unmodified. On the other hand, in d+Au collisions, the meson production exhibits a slight enhancement in this $p_T$ region while the baryon production exhibits a much stronger enhancement. In this talk, the $p_T$ spectra and ratios of identified charged hadrons $\pi^{\pm}$, $K^{\pm}$, $p$, and $\bar{p}$ in 5 different centrality classes for each collision species will be presented. Implications for particle production will be discussed.

Speaker: Ron Belmont (University of Michigan, Wayne State University)

Slides Belmont_SQM13.pdf

9 Strangeness in ALICE

Speaker: Lee Stuart Barnby (University of Birmingham (GB))

Slides ALICEStrangenessSQM2013.pdf

16:20 Break

Plenary 3

Convener: Jean Cleymans (University of Cape Town (ZA))

10 Heavy Flavours and Quarkonia

Speaker: Raphael Granier De Cassagnac (Ecole Polytechnique (FR))

Slides 2013.07.22.SQM13.pptx

11 Open and Hidden Heavy Flavor Production in pp, pA and AA Collisions

Speaker: Ramona Vogt (LLNL)

Paper SQM13_proc.pdf

Slides sqm13.pdf

Tuesday, 23 July

Plenary 4

Convener: Francesco Becattini (Unversity of Florence)

12 ALICE results on quarkonium production in pp, p-Pb and Pb-Pb collisions

Speaker: Dr Giuseppe Bruno (Universita e INFN (IT))

Slides 2013-Jul-20-conferencefile-Bruno_SQM13_Quarkonia.pdf 2013-Jul-20-conferencefile-Bruno_SQM13_Quarkonia.pptx

13 Heavy flavour production at STAR

Heavy quarks are produced early in the heavy-ion collisions and they are expected to interact differently from light quarks with the Quark Gluon Plasma (QGP); therefore, they are unique probes of the QGP properties. Moreover, their production and elliptic flow are sensitive to the medium dynamics. These measurements for open heavy flavour sector are crucial for understanding the parton energy loss mechanism and the degree of thermalization of the QGP. They can be also used to determine the transport coefficients of the QGP. Furthermore, production of various quarkonia states can provide insight into thermodynamic properties of the QGP since different states are predicted to disassociate (due to the Debye screening of the quark-antiquark potential) at different temperatures. In this talk, we report on recent STAR results on heavy flavour production at $\sqrt{s_{NN}}$ = 200, 62.4 and 39 GeV. We present nuclear modification factor and elliptic flow of open charm mesons and electrons from semileptonic decays of heavy flavor hadrons. We also report on new measurement of energy dependence of the J/psi production. STAR data are compared to theoretical model calculations and physics implications are discussed.

Speaker: Daniel Kikola (Warsaw University of Technology)

Paper HeavyFlavorStar_v3.pdf

Slides SQM_STAR_HeavyFlavor.pdf

14 Quarkonia and heavy flavors latest PHENIX results

Heavy quarks and quarkonia are mostly produced in the first steps of a collision, and then are sensitive to the whole evolution of the system, and in particular to the initial stage, which makes also of the heavy quarkonia an excellent probe of the quark gluon plasma formation in heavy ion collisions. Other effects also occur, such as partonic distributions modification in cold nuclear matter, and a multidimensional description is necessary to get a sufficient set of equations to disentangle the various contributions. In particular, the characterization of the production processes in p-p and p or d induced collisions with ions is critical in the extraction of the additional ion-ion collisions effect. The Relativistic Heavy Ion Collider has been delivering the widest range of systems and energies, from p-p to Au-Au through d-Au and Cu-Au, from 7.6 to 200 GeV (n-n collision), allowing the PHENIX experiment to start to explore these various experimentally available dimensions, also versus rapidity and transverse momentum, for open and hidden charm and beauty. Recent PHENIX results of their production through single lepton or pairs of leptons, including J/psi, psiprime, Chi_c, Upsilon, open charm and beauty, will be presented.

Speaker: Mr Denis Jouan (IPN CNRS/IN2P3)

Slides plenary4_DJouan_PHENIX_SQM13_quarkonia_heavy_flavor.pdf plenary4_DJouan_PHENIX_SQM13_quarkonia_heavy_flavor.pptx

10:30 Break

Plenary 5

Convener: Karel Safarik (CERN)

15 Open heavy-flavour results from ALICE

Speaker: Diego Stocco (Laboratoire de Physique Subatomique et des Technologies Associe)

Slides stocco_HF_ALICE.pdf

16 Open and closed heavy-flavour suppression in heavy-ion collisions with CMS

The Compact Muon Solenoid (CMS) is fully equipped to measure quarkonia in the di-muon decay channel in the high multiplicity environment of nucleus-nucleus collisions. Quarkonia are especially relevant for studying the quark-gluon plasma since they are produced at early times and propagate through the medium, mapping its evolution. CMS has measured the nuclear modification factors of non-prompt J/psi (from b-hadron decays), prompt J/psi, inclusive psi(2S), and the first three Y states in PbPb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV. A suppression of non-prompt J/psi, which is sensitive to the in-medium b-quark energy loss, has been measured at relatively high p_T (6.5 < p_T < 30 GeV/c) in PbPb collisions, compared to the yield in pp collisions scaled by the number of inelastic nucleon-nucleon collisions. For prompt J/psi in the same kinematic range, a strong, centrality-dependent suppression is observed. Such strong suppression at high p_T has previously not been observed at RHIC. At midrapidity and high p_T, psi(2S) show an even stronger suppression than J/psi. Furthermore, CMS has measured the suppression of the three Y states, separately, down to p_T = 0. A clear ordering of the suppression with binding energy is observed, as expected from sequential melting. The status of quarkonium measurements in pPb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV will be also presented.

Speakers: Mihee Jo (Korea University (KR)), The CMS Collaboration (CMS)

Slides 23July2013_MiheeJo_SQM2013_v3.pdf

17 Strange particle production in Monte Carlo generators in pp and pPb collisions at the LHC

Speaker: Klaus Werner (SUBATECH)

Slides sqm.pdf

Flow

Convener: Wojciech Broniowski (IFJ PAN)

18 Anisotropic flow of identified particles in Pb-Pb collisions at √ sN N = 2.76 TeV with the ALICE detector

Anisotropic flow is an important observable to study the properties and the evolution of the system created in heavy-ion collisions. We present measurements of anisotropic flow of strange and multi-strange particles, including Ks, Λ, Ξ, Ω and φ, in Pb–Pb collisions at \sqrt{s_{NN}} = 2.76 TeV recorded with the ALICE detector. The results are compared to hydrodynamic model calculations, blast-wave fit and the measurements at top RHIC energy. Particle mass dependence and scaling with the number of quarks of the anisotropic flow will be also discussed.

Speaker: You Zhou (NIKHEF and Utrecht University (NL))

Slides SQM2013_YZ.pdf

19 Recent ATLAS results on flow measurements in lead-lead and proton-lead collisions

ATLAS has performed a detailed measurement of event-by-event flow in lead-lead collisions at the LHC. The Fourier coefficients, v2-v4, of the azimuthal angle distribution of charged particles measured in the ATLAS inner detector (|eta| < 2.5) are extracted in each of 48 million minimum-bias Pb+Pb collisions. The v2-v4 distributions are measured for a variety of centrality intervals over three transverse momentum ranges, pT > 0.5 GeV, pT > 1 GeV and 0.5 < pT < 1 GeV. The measurements of the vn distributions, unfolded for experimental resolution will be presented. The relationship between the shapes of the vn distributions and the collision geometry and initial-state fluctuations will be discussed. The results will be compared with theoretical calcualtions of initial-state eccentricity distributions and theoretical calculations of the vn distributions using hydrodynamics.

Speaker: Adam Trzupek (Henryk Niewodniczanski Inst. Nucl. Physics, PAN)

Slides SQM13_AdamTrzupek_v3.pdf

20 Thermalization of massive partons in anisotropic medium

At first, we exactly solve the relaxation-time approximation Boltzmann equation for a system which is transversely homogeneous and undergoing boost-invariant longitudinal expansion. We compare the resulting exact numerical solution with approximate solutions available in the anisotropic hydrodynamics and second order viscous hydrodynamics frameworks. In all cases studied, we find that the anisotropic hydrodynamics framework is a better approximation to the exact solution than traditional viscous hydrodynamical approaches. In the next step we generalize the kinetic approach to include finite parton masses and analyze their impact on the thermalization process. The talk is partially based on the recent eprint: "Anisotropic Hydrodynamics for Rapidly Expanding Systems" by W. Florkowski, R. Ryblewski, and M. Strickland, arXiv:1304.0665

Speaker: Radoslaw Ryblewski (Institute of Nuclear Physics PAS)

Slides talk.pdf

21 Effects of Jets in the Flow Observables

The study of the transverse momentum anisotropy of the particles produced in heavy ion collisions is one of the most important experimental observable to investigate the collective behavior of the systems created in such collisions. Recent studies show that the complexity of the nature of the system evolution, such as initial condition fluctuations and jets, may lead to important effects in the flow coefficients and, therefore, to misinterpretation of the results obtained. In this study, we used combined simulated events produced with a hydrodynamic model which allows inhomogeneous initial condition and proton-proton collisions produced with Pythia event generator to create a final set of particles to be analyzed with the usual experimental flow calculation techniques. Although this modest approach is somehow unrealistic, since it does not include the interaction of the jet with the medium, our results have shown a good agreement of the behavior of the elliptic flow coefficient as a function of the transverse momentum up to 6 GeV/c for Au+Au collisions at 200 GeV. Despite each model alone is not able to describe the full range, the combination of both set of particles as seem by the flow calculation techniques may be the key to explain the behavior observed in experimental data.

Speaker: Prof. Jun Takahashi (UNICAMP)

Slides SQM2013_Takahashi.pdf

22 Landau hydrodynamics for non-central heavy-ion collisions and longitudinal scaling of elliptic flow

Landau solution of hydrodynamics is generalized for the non-central high-energy nuclear collisions. The multiparticle production after hydrodynamic expansion from the transversely asymmetric initial state shows elliptic flow formation. Moreover, obtained solution does reproduce the observed longitudinal scaling of the elliptic flow for the different collision energies at LHC and RHIC. It will be argued, that the analyticity of the solution allows us to separate collective pressure driven flow effects from the initial conditions.

Speaker: Karolis Tamosiunas (Vilnius University (LT))

Slides Presentation-Tamosiunas-SQM2013.pptx.pdf

23 Charge asymmetry dependency of {$\pi$}/K anisotropic flow in U+U {$\sqrt{s_{NN}}$} = 193 GeV and Au+Au {$\sqrt{s_{NN}}$} = 200 GeV collisions at STAR

Theoretical study\cite{myref1} indicates that a chiral magnetic wave at finite baryon density could induce an electric quadrupole moment in QGP produced in heavy-ion collisions. The electric quadrupole deformation will lead to a difference in elliptic flow of hadrons, by increasing {$v_{2}$} of negatively charged hadrons and decreasing {$v_{2}$} of positively charged ones. The magnitude of this difference is predicted to be proportional to the charge asymmetry {$A_{ch}$}, defined as {$A_{ch}\equiv \left (\bar{N}_{+} -\bar{N}_{-} \right )/\left ( \bar{N}_{+} +\bar{N}_{-} \right )$}. Such charge asymmetry dependency of pion elliptic flow has been observed in Au+Au collisions at the STAR experiment. \\ \newline Here we present elliptic flow measurements of charged pions and kaons at low momentum, as a function of {$A_{ch}$}, in U+U collisions at {$\sqrt{s_{NN}}$} = 193 GeV at STAR. The {$v_{2}$} difference for charged kaons is suggested\cite{myref1} to have a weaker {$A_{ch}$} dependency than that of pions due to hadronic effects. Our measurements for both serve as important consistency checks for the phenomena due to the chiral magnetic wave.

Speaker: Qi-Ye Shou (SINAP, BNL)

Slides SQM2013_qyshou_presentation_v2.pdf

Low Energy / Heavy Flavour

24 Influence of the in-medium kaon potential on kaon production in heavy ion collisions

The inclusive cross section, polar angle distribution and the direct transverse momentum of K+ mesons in C + C, Ni + Ni and Au + Au collisions at incident energies from 0.6 to 2.0 A GeV are studied using the Quantum Molecular Dynamics model based on the covariant kaon dynamics, and compared with the KaoS data of GSI. The calculated K+ yields consist with experiment data for a soft and hard nuclear equation of state (compression modulus K = 200 , 380 MeV respectively) when including the in-medium K+ potential (its value at saturation density is ). The experimental data for the polar distribution of Au + Au collisions at 1.5 A GeV and Ni + Ni collisions at 1.93 A GeV are slightly more forward/back than theoretical predicts and rather flat. The direct transverse momentum of K+ mesons in Ni + Ni collisions at 1.93 A GeV is not obviously affected by the in-medium K+ potential.

Speaker: Dr Pornrad Srisawad (Department of Physics, Faculty of Science, Naresuan University, 65000 Phitsanulok Thailand)

Slides PornradSQM2013.pdf PornradSQM2013.ppt

25 Phenomenology of quarkyonic matter in heavy-ion collisions

I will discuss the phase structure of matter at moderate temperature and chemical potential, relevant for the lower energy runs at RHIC as well as the upcoming experiments of NICA and FAIR. Motivated by large Nc physics, I will argue that the non-perturbative structure of QCD can give rise to hitherto little explored phenomena, such as the coexistence of confinement with perturbative quark degrees of freedom. I will however show that this "quarkyonic phase" is defined by a percolation-type phase transition line which curves in "number of colors", as well as density and temperature. Given theoretical uncertainities in dealing with matter at this regime, therefore, a phenomenological and experimental investigation of matter at high chemical potential might be decisive to determine if the quarkyonic phase does in fact exist. I will discuss possible experimental signatures of this new state of matter,concentrating on electromagnetic signals as well as strangeness enhancement.

Speaker: Giorgio Torrieri (JW Goethe Universitat, Frankfurt)

Slides sqm.pdf

26 Strongly interacting parton-hadron matter in- and out-off equilibrium

We study the equilibrium properties of strongly-interacting infinite parton-hadron matter and the non-equilibrium dynamics of heavy-ion collisions from SIS to LHC energies within the Parton-Hadron-String Dynamics (PHSD) transport approach, which incorporates explicit partonic degrees of freedom in terms of strongly interacting quasiparticles (quarks and gluons) in line with an equation of state from lattice QCD as well as the dynamical hadronization and hadronic collision dynamics in the final reaction phase. The equilibration of different observables on light and strange sector and their fluctuations in the QGP and also transport coefficients, such as shear and bulk viscosity, electric and heat conductivity are presented. We investigate as well as out-off equilibrium phenomena seen in azimuthal angular distribution in higher harmonics (v1,v2,v3,v4), particle spectra etc. in heavy-ion collisions. We focus on the sensitivity of different observables (in particular, involving strange particles) to the "traces" of the QGP from low to ultrarelativistic energies.

Speaker: Elena Bratkovskaya (FIAS)

Slides Bratkovskaya_SQM_Jul13.pdf

27 The Production of K0's in p+p Reactions

Since the recent discovery of a massive neutron star of about 1.97 solar masses [1] the discussion about a possible existence of a condensed kaon matter inside the neutron star has been revived [2,3]. Kaons not only influence the nuclear EOS [1,2], but also play an important role for the cooling process of a neutron star [4]. Thus a better understanding of the kaon nucleon/nucleus interaction is urgently requested. For example, characteristics of the interaction such as the KN potential and the KN scattering in medium still need further investigation. These properties can be obtained by comparisons of proton-nucleus or heavy ion data to transport models [5,6,7]. Hence the models should be able to reproduce elementary reactions at the first place. In this contribution we present high statistics K0s data from p+p collisions at Ekin = 3.5 GeV measured by the HADES detector at GSI (Darmstadt, Germany). The measurement of this energy regime is of particular importance because of two reasons. First of all there is a lack of data at these energies. Second of all it is not clear, whether the processes are dominated by resonance productions or already need to be described via string models (e.g. PYTHIA or FRITIOF) in the transport calculations. In both cases the constraints put up by this measurement for the transport models will be essential for the interpretation of the physics measured by CBM at the future FAIR facility. The good statistics in the p+p data set allow for a double differential analysis in pt-y and angular distributions in momentum bins. Exclusive production channels as p + p -> Y + Delta++ + K0, p + p -> Y + p + pi+ + K0 and others have been studied and the extraction of the relative cross sections has been carried out. In particular, the role played by the Delta++ resonance has been adressed. These results can be used to constrain the transport models. Results of the ongoing investigation and the influence of angular anisotropy will be presented in the contribution. [1] P.B. Demorest et al., Nature 467, 10811083 (2010); [2] K. Masuda et al., arXiv:1205.3621[nucl-th] (2012); [3] K. Kim et al., Phys. Rev. C 84, 035810 (2011); [4] S. Kubis et al., Nucl. Phys. A, 720 189-206 (2003); [5] G. Agakishiev et al., Phys. Rev. C 82, 044907 (2010); [6] M. B¨uscher et al., Eur. Phys. J. A 22, 301-317 (2004); [7] M.L. Benabderrahmane et al., PRL 102, 182501 (2009).

Speaker: Jia-Chii Berger-Chen (Technische Universitaet Muenchen (DE))

Slides SQM13_jbergerchen_V2.pdf

28 Effect of quark gluon plasma on charm quark produced in relativistic heavy ion collision

Charm quarks are produced mainly in the pre-equilibrium stage of heavy ion collision and serve as excellent probes entering the thermalized medium medium. They come out with altogether different momentum and energies and fragments into D mesons and later decay into non-photonic electron which are experimentally observed. Here we present effects of Quark Gluon Plasma on charm quark production using two different models, one of which is the calculations based on Wang-Huang-Sarcevic model of multiple collisions and other using the calculations of Parton Cascade Model based on Microscopic Boltzmann Transport Equation.

Speaker: Mohammed Younus (Variable Energy Cyclotron Centre)

Slides SQMmdy_talk2013.pdf

29 Gluon radiation by heavy quarks

It is generally assumed that in ultrarelativistic heavy ion collisions a plasma of quarks and gluons is produced, and then quickly expands and hadronizes. The main objective of present experiments at ultrarelativistic heavy ion colliders is to study this plasma. The study of the plasma properties is difficult because the initial momentum distribution of the light quarks is not known and that before being detected the system passes the chiral/confinement phase transition in which hadrons are formed. Hadrons interact on the way to the detectors what modifies their spectrum. Therefore soft light hadrons do not carry information on the early stage of the plasma. The situation is much better for heavy quarks (c and b) which are created in hard processes. Here perturbative QCD allows for the calculation of the production cross sections (in contradistinction to light quarks) and these cross sections have also been measured. Also the details of the chiral/confinement phase transition are less important than for light quarks because, due to its mass, the momentum of the heavy quark determines the momentum of the open charm hadrons. In addition, the momentum distribution at production and at the transition is very different from that expected if the heavy quarks are in thermal equilibrium with the plasma of light quarks and gluons. Therefore the modification of the initial momentum distribution by the interaction of the heavy quarks with the plasma carries information on the plasma properties. The interaction of the heavy quark with the plasma has two parts, elastic collisions and radiative collisions. For the first a model was developped [1] in which the cross section of the elementary interactions are calculated by perturbative QCD with a running coupling constant and an infrared behavior adjusted so as to match hard thermal loop calculations. Embedding these cross sections in the hydrodynamical description of the expanding plasma of Heinz and Kolb it was shown that the collisional energy loss underpredicts the measured energy loss of heavy mesons at large momenta as well as their elliptic flow by roughly a factor of two. It is the purpose of the present work to extend our pQCD calculation toward the calculation of the radiative energy loss. To this end we compute the gluon emission cross section of a heavy quark colliding a light parton from the plasma in pQCD at leading order. We first derive the high-energy approximation that naturally extends results obtained by Gunion and Bertsch for the light quark sector to heavy quarks. We next show that it is possible to compute the complete energy dependence of the result. This allows us to assess the range of applicability in energy of the high-energy approximation. The latter has the advantage of leading to very compact expressions for the various integrated cross sections and also of making more transparent the discussion of various physical phenomena. We discuss in particular the relevance of the dead cone effect. [1] P.B. Gossiaux and J. Aichelin, Phys Rev C78, 014904 (2008)

Speaker: Thierry Gousset (Subatech)

Slides gousset.pdf

Strangeness 1

Starting from lower energies

30 System-size dependence of charged kaon and pion production in nucleus-nucleus collisions at beam energies of 40A GeV and 158A GeV

The NA49 collaboration measured the rapidity and transverse mass distributions of kaons and pions in Pb+Pb collisions at different centralities. These data are complemented by results from the small systems C+C and Si+Si. We find that the centrality dependence of kaon and pion production is reproduced by microscopic transport model calculations (HSD and UrQMD2.3) within 20% or better. The mean transverse mass evolves with centrality as expected for increased stopping and en- ergy deposition. The centrality dependence of the widths of the rapidity distributions in Pb+Pb collisions does not smoothly connect to results from the small systems p+p, C+C, and Si+Si. In Pb+Pb collisions the K/π ratios show a smooth increase with centrality at both beam energies with saturation setting in around 100-200 (60-100) wounded nucleons for 40A GeV (158A GeV). This behavior fits well into the trends observed at lower (AGS) and higher (RHIC) energies.

Speaker: Herbert Stroebele (Johann-Wolfgang-Goethe Univ. (DE))

Paper SQM2013-contribution.pdf SQM2013-contribution-v1.pdf

Slides HS-SQM13_v2.pdf

31 Status and results from the NA61/SHINE experiment at the CERN SPS

Present status and recent results shall be presented from the NA61/SHINE experiment at the CERN SPS. The physics program is concentrated along heavy-ion physics and the study of hadron production in p+p and h+A collisions. The heavy-ion program mostly address the study of onset of deconfinement and search for the critical point of the strongly interacting matter, while the p+p and h+A program is also meant to provide valuable reference data for neutrino beam experiments and large coverage cosmic shower observatories. The quantitative results to be shown are identified charged pion and Kaon production spectra in p+C collisions, along with preliminary K^0_s and Lambda yields. These results are mostly used by neutrino beam communities. Preliminary identified charged pion, Kaon and proton spectra in p+p collisions shall also be presented. These data are mostly relevant for the heavy-ion program of NA61 as a baseline. Along with single particle spectra, results on the energy and system size dependence on event-by-event fluctuation measures shall also be presented. Finally, the near plans and farther future perspectives shall also be mentioned, such as the Pb+Pb energy scan and open charm measurement possibilities.

Speaker: Dr Zoltan Fodor (Hungarian Academy of Sciences (HU))

Slides na61_status_v3.pdf

32 Production of pi/K/p in pp and Pb-Pb collisions measured with ALICE.

The ALICE detector features multiple particle identification systems including: the Time Projection Chamber (TPC), the Inner Tracking System (ITS), a time-of-flight system (TOF) and a Ring-imaging Cherenkov detector (HMPID). This combination of detectors along with the excellent tracking capabilities of ALICE provides us with the opportunity to measure the production of pi/K/p over a broad transverse momentum (pT) range, from 100 MeV/c up to 20 GeV/c. Particle identification at low pT (below 1GeV/c) is performed using the energy loss of particles in the ITS and the TPC. The TOF contributes to the identification for the pT range between 0.5 GeV/c and 3-5 GeV/c (depending on the particle type and the colliding system). For high pT (up to 20 GeV/c), particles are identified with the HMPID or the relativistic rise of the energy loss in the TPC. In this talk an overview of the ALICE results on the production of pi/K/p in pp collisions at sqrt(s) = 0.9, 2.76 and 7 TeV, and Pb-Pb collisions at sqrt(s_NN) = 2.76 TeV will be presented. The ALICE results from pp collisions provide constraints for the commonly used event generators and are the baseline for the Pb-Pb measurement. The Pb-Pb results will be compared to statistical models and hydrodynamic calculations at low pT and recombination models at intermediate pT. The high pT region provides constraints on models describing parton energy loss in the hot and dense medium.

Speaker: Marek Chojnacki (University of Copenhagen (DK))

Slides MChojnackiSQMv7.pdf

33 Kaon femtoscopy in 200 GeV central Au+Au collsions at STAR

Three-dimensional source extraction techniques allow us to get an insight to the space-time extent and the freezeout dynamics of the hot and dense medium created in RHIC high energy heavy ion collisions, using Bose-Einstein correlated like-sign hadron pairs. Three-dimensional analyses of the pion source revealed a heavy, non-Gaussian tail in the "out" direction. The interpretation of these pion sources in terms of pure hydrodynamical evolution is, however, complicated by the strong contribution of feed-down from long-lived resonances to the source. On the other hand, kaons provide a much cleaner probe of the expanding fireball. We present a recent three-dimensional kaon correlation analysis in central Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV, using Cartesian harmonics decomposition technique. We compare the three-dimensional spatial source function of kaons to that of pions, and to a thermal model of source evolution. We also present results on the three-dimensional extent of the kaon source with respect to the pair transverse momentum, and compare it to predictions of two different hydrodynamical models.

Speaker: Robert Vertesi (Nuclear Physics Institute of the Czech Academy of Sciences)

Slides sqm13-star-kkimg-vertesi.pdf sqm13-star-kkimg-vertesi.pptx

34 Study of h-h and V0-h angular correlations in Pb-Pb collisions at sNN = 2.76 TeV

Two-particle angular correlations provide a powerful tool to study jets and their modication in ultra-relativistic heavy-ion collisions. The study of the particle species dependence of correlation structures as a function of transverse momentum provides additional information on the particle production mechanisms at LHC energies. In this contribution we will present studies of a near-side jet-like correlation peak in (eta,phi) space for Pb-Pb collisions at sqrt(s_NN) = 2.76 TeV. The measurement is performed using the correlations formed by pairs of high pT (6 < pT_trig < 15 GeV/c) , and Lambda, antiLambda, K0S (trigger particles) associated with unidentified charged hadrons in the transverse momentum range 3 GeV/c < pT_assoc < pT_trig. The jet-like peak yield and width for different trigger strange particles are investigated as a function of pT_trig, pT_assoc and collision centrality.

Speaker: Marek Bombara (Pavol Jozef Safarik University (SK))

Slides MBombara_V0Ch_SQM13.pdf

35 Multiplicity fluctuations of identified hadrons in p+p interactions at SPS energies

The problem of pinning down the critical point of strongly interacting matter still puzzles the community. One of the answers suspected to emerge in the near future will surely come from NA61/SHINE - a fixed-target experiment aiming to discover the critical point as well as to study the properties of the onset of deconfinement. This goal will be reached by obtaining precise data on hadron production in proton-proton, proton-nucleus and nucleus-nucleus interactions in a wide range of system size and collision energy. In this contribution inclusive spectra of identified hadrons in p+p interactions at the SPS energies will be shown as a function of transverse momentum/mass and rapidity. New data will be compared with the corresponding results of NA49 for central Pb+Pb collisions as well as with some model predictions.

Speaker: Andrzej Gabriel Wilczek (University of Silesia (PL))

Slides awilczekSQM.pdf

16:00 Break

16:00 Break

16:00 Break

Heavy Flavour 1

Convener: Wojciech Florkowski (Institute of nuclear Physics, Krakow)

36 Nuclear Modification Factor and Elliptic Flow of Muons from Heavy-Flavour Hadron Decays in Pb–Pb Collisions at √ sNN = 2.76 TeV with ALICE

Nuclear Modification Factor and Elliptic Flow of Muons from Heavy-Flavour Hadron Decays in Pb–Pb Collisions at √ sNN = 2.76 TeV with ALICE X. Zhang for the ALICE Collaboration Lawrence Berkeley National Laboratory, Berkeley, CA, U. S. A. The LHC heavy-ion physics program aims at investigating the properties of strongly-interacting matter in extreme conditions of temperature and energy density, where the formation of the Quark- Gluon Plasma (QGP) is expected. In high-energy heavy-ion collisions, heavy quarks are regarded as efficient probes of the properties of the QGP as they are created on a very short time scale in initial hard scattering processes and subsequently interact with the medium. In the high transverse momentum region, the suppression of the heavy-flavour production, quantified by means of the nuclear modification factor, $R_{\rm AA}$, defined as the ratio of the yield measured in Pb--Pb to that observed in pp collisions scaled with the number of binary nucleon-nucleon collisions, is used to study the heavy quark in-medium energy loss mechanisms. The heavy-flavour elliptic flow, the second order coefficient of the Fourier expansion of particle azimuthal distributions, provides insights on the degree of thermalization of heavy quarks in the deconfined medium and carries information on the path length dependence of parton energy loss in the low and high transverse momentum region, respectively. ALICE, the only detector designed and optimized for heavy-ion physics at the LHC, measures open-heavy flavours at forward rapidity ($2.5<y<4$) using semi-muonic decays. The latest results on the nuclear modification factor and elliptic flow of muons from heavy-flavour decays in Pb--Pb collisions at $\sqrt{s_{\rm NN}}=2.76$~TeV will be presented.

Speaker: Xiaoming Zhang (Lawrence Berkeley National Lab. (US))

Slides SQM2013_XiaomingZhang.pdf

37 Heavy Quark Energy Loss and Bulk Physics

Bulk matter phenomena in heavy ion collisions is characterized by an extremely small viscosity to entropy ratio best understood by strong coupling dynamics described by the AdS/CFT correspondence. We test a consistent description of QGP physics by applying this AdS/CFT paradigm to the energy loss of heavy quarks. Previously we found consistency with the non-photonic electron data at RHIC but a significant, systematic oversuppression compared to LHC D meson measurements; b quark energy loss is so far consistent within the large uncertainties of current LHC results. Previous predictions for light mesons are also suggestive of oversuppression in this AdS/CFT picture. We present an attempt to resolve the discrepancy between the AdS/CFT energy loss predictions and data by incorporating a more realistic matching between the AdS/CFT world and ours, and thus resolve the current contradiction between the low momentum and high momentum physics phenomena seen at RHIC and LHC.

Speaker: Dr W A Horowitz (University of Cape Town)

Slides 130723(SQM)Horowitz.pptx

38 Heavy-flavor azimuthal correlations of D mesons

The observation of strong jet quenching and the suppression of high-$p_t$ hadrons in relativistic heavy-ion collisions are striking experimental signatures for the formation of a deconfined QCD plasma in which partons suffer from in-medium energy loss. In particular, heavy quarks are considered as suitable probes for revealing the properties of the produced matter as they are created at very early stages in hard scattering processes and assumed not to thermalize completely within the medium. Typical observables for the interaction of heavy quarks with the medium constituents are the nuclear modification factor $R_{AA}$ and the elliptic flow $v_2$, which we present within a combined Monte-Carlo approach and realistic fluid dynamic description of the expanding plasma for both RHIC and LHC energies. In the main part of this talk we will investigate the potential of correlations between heavy quarks and anti-quarks to reveal basic principles of energy loss scenarios at LHC. At low $p_t$ any correlation of the initially heavy quark-antiquark pair is lost due to thermalization, at larger $p_t$, however, these correlations in $p_t$ and azimuthal angle $\phi$ survive and show distinctive features for purely elastic and elastic plus radiative energy loss mechanisms. We discuss these results in view of the centrality dependence, next-to-leading order production processes and details of the equation of state.

Speaker: Dr Marlene Nahrgang

Slides sqm_marlene.pdf

39 Heavy Flavour Suppression: Boltzmann vs Langevin

The propagation of heavy flavour through the quark gluon plasma has been treated commonly within the framework of Langevin dynamics, i.e. assuming the heavy flavour momentum transfer is much smaller than the light one. On the other hand a similar suppression factor R_AA has been observed experimentally for light and heavy flavor. We present a thorough study of the thermalization dynamics and of the approximations involved by Langevin equation by mean of a direct comparison with the full collisional integral within the framework of Boltzmann transport equation. We found that it is difficult to achieve thermalization in Langevin dynamics for a realistic momentum dependence of the drag and diffusion coefficients. The nuclear suppression factor, $R_{\mathrm AA}$ and the elliptic flow $v_2^{HF}$ of the charm and bottom quarks have been evaluated at RHIC and LHC energies within both the Langevin and Boltzmann approach. We have compared the results obtained in both approaches which can differ substantially leading to quite different values extracted for the the heavy quark diffusion coefficient.

Speaker: Dr Santosh Kumar Das (Department of Physics and Astrophysics, University of Catania)

Slides SQM_BM_LV.pdf

40 Shear viscosity of a multi-component hadronic system

Shear viscosity $\eta$ and entropy density $s$ of a hadronic resonance gas are calculated consistently within the Chapman-Enskog approximation using the $K$-matrix parameterization of hadronic cross sections which preserves the unitarity of the $T$-matrix. In the $\pi-K-N-\eta$ mixture considered, a total of 82 resonances up to 2 GeV were included. Comparisons are also made to results with other hadronic cross sections such as the Breit-Wigner (BW) and, where available, experimental phase shift (EXP) parameterizations. The BW parameterization fails to preserve unitarity of the $T-$matrix for nearby resonances, whereas experimental phase shifts are not available for all resonances considered. Hadronic interactions among the many resonances are shown to decrease the shear viscosity and increase the entropy density leading to a reduction of $\eta/s$ as the QCD phase transition temperature is approached.

Speaker: Anton Wiranata (Lawrence Berkeley Lab)

Slides wiranata_SQM_13.pdf

Phase Transition

Convener: Joerg Aichelin (Unknown)

41 An Inverse Magnetic Catalysis Effect Induced by Sphalerons

We find that the barrier between topologically in-equivalent vacua is lowered at the presence of external magnetic field. As a consequence, the imbalanced chiral quark density arises due to the sphaleron transition at finite temperatures. It quantitatively explains and describes the unusual phenomena of the inverse magnetic catalysis, which was numerically found to happen at the transition between the hadron, low-temperature phase and hot, magnetized quark-gluon plasma. We also propose revelant singantures of this effect to be experimentally accessible in the magnetised plasma environment created in noncentral heavy-ion collisions at the LHC.

Speaker: Dr Jingyi Chao (Institute of High Energy Physics, CAS)

Slides ppt_SQM2013.pdf

42 Flavor-specific behavior of conserved charge fluctuations at the QCD confinement transition

Great experimental and theoretical effort is being put into the detailed study of the confinement/deconfinement transition in QCD matter. Susceptibilities of conserved quantities, which are related to the statistical moments of particle multiplicity distributions measured in heavy-ion collisions, provide important insight, in particular, into the composition of the produced matter. Based on a study of the higher moments of quark-flavor quantum number distributions, I will argue in this talk about a potential hierarchy in the hadronization sequence of different quark flavors during the course of an ultra-relativistic heavy-ion collision. Such a flavor-dependence would, in particular, influence the production of strange versus non-strange (light-quark) hadrons in comparison with standard approaches which assume a flavor-independent hadronization. The presented study will rest upon an interplay between recent lattice QCD results for the quark-number susceptibilities of different quark flavors, recent measurements of particle multiplicity distributions from the ALICE collaboration and phenomenological models that aim to relate the thermal properties of the QCD matter at the confinement/deconfinement transition to final state hadron measurements.

Speaker: Dr Marcus Bluhm (SUBATECH Nantes)

Slides FlavorHierarchySQMv1.pdf

43 Quark-hadron phase transition in a three flavor PNJL model

We extend our previous study of the quark-hadron phase transition at finite temperatures with zero net baryon density by two flavor Nambu-Jona-Lasinio model with Polyakov loop [1] to the three flavor case. At low temperatures, only mesonic correlations, mainly due to mesonic collective excitations, dominate the pressure while thermal excitations of quarks are suppressed by the Polyakov loop. As temperature increases, mesonic collective modes melt into the continuum of quark and anti-quark so that hadronic phase changes continuously to the quark phase where quark excitations dominate pressure. We add the gluon pressure in a phenomenological way through the effective potential for the Polyakov loop. Since we introduce mesons as not elementary fields but auxiliary fields made from quarks, we can describe the phase transition between hadronic phase and quark phase in a unified fashion. [1] Kanako Yamazaki and T.Matsui, arXiv:1212.6165 [hep-ph].

Speaker: Kanako Yamazaki (University of Tokyo)

Slides yamazaki.pdf

44 Transport coefficients from the Nambu-Jona-Lasinio model for SU(3)f

Based on the Nambu-Jona-Lasinio model for 3 flavours we study the transport properties of strongly interacting matter in vicinity of the phase transition. We present our results on the temperature dependence of the shear and bulk viscosity (calculated within the relaxation time formalism), as well as of the electric and heat conductivity. We compare these results with recent lattice data and the transport coefficients of the DQPM (dynamical quasiparticle model). These transport coefficients allow for discussing quantitatively how fast particles traverse the quark gluon plasma and open the possibility to compare different approaches for the expansion of the quark gluon plasma created in ultrarelativistic heavy ion collisions.

Speaker: Rudy Marty (FIAS (Frankfurt, GERMANY))

Slides SQM2013_Marty.pdf

45 Diffusion of non-Gaussianity in heavy ion collisions

We investigate time evolution of higher-order cumulants of bulk fluctuations of conserved charges in the hadronic stage in heavy ion collisions. The dynamical evolution of the non-Gaussian fluctuations are modeled by the diffusion master equation. In this model, we show that the fourth-order cumulant is suppressed compared with the recently observed second-order one at ALICE. Significance of various cumulants as functions of rapidity acceptance as experimental observables to probe dynamical history of fireballs are emphasized.

Speaker: Masakiyo Kitazawa (Osaka University)

Slides 1307SQM_DME.pdf 1307SQM_DME.pptx

Polarisation observables and eA

46 Turbulence, Vorticity and Lambda Polarization

Due to the low viscosity and strongly interacting QGP at high LHC energies flow fluctuations were observed up to the 8th flow harmonics. Similarly rotation, turbulence and even Kelvin-Helmholtz Instability were predicted and these may be observable by different methods. Apart of the usual flow harmonics analysis, other methods like two particle correlations, or particle polarizations may arise as a consequence of these processes. The appearance of turbulent phenomena in these experiments would be additional direct proof of the low viscosity. In particular we observed in 3+1D fluid dynamical calculations at LHC energy that Lambda polarization arising from thermal and mechanical equilibrium, can provide measurable signal in given azimuthal directions. This mechanism is considerably stronger than the polarization arising from the direct electro-magnetic effect of the strong and rapidly changing fields during the collision.

Speaker: Laszlo Pal Csernai

Slides 1-Csernai-SQM-Birmingham.pdf 1-Csernai-SQM-Birmingham.ppt

47 Relativistic distribution function for particles with spin at local thermodynamical equilibrium

We present an extension of relativistic single-particle distribution function for weakly interacting particles at local thermodynamical equilibrium including spin degrees of freedom, for massive spin 1/2 particles. We infer, on the basis of the global equilibrium case, that at local thermodynamical equilibrium particles acquire a net polarization proportional to the vorticity of the inverse temperature four-vector field. The obtained formula for polarization also implies that a steady gradient of temperature entails a polarization orthogonal to particle momentum. The single-particle distribution function in momentum space extends the so-called Cooper-Frye formula to particles with spin 1/2 and allows to predict their polarization, and particularly of Lambda hyperons, in relativistic heavy ion collisions at the freeze-out.

Speaker: Eduardo Grossi (University of Florence & INFN Florence)

Paper grossi_sqm2013.pdf

Slides Grossi-sqm2013.pdf

48 Hyperon Polarization in Heavy ion Collisions

The STAR collaboration has measured the Λ and anti-Λ polarizations in 200 GeV Au-Au collisions [1]. These results can be understood in terms of a model [2], [3], that we proposed recently, based on the hydrodynamical model, and taking into account the effect of the final-state interactions (that occur in the hadronic phase) between the hyperons and other produced particles. These final interactions are described in terms of chiral effective lagrangians, that consider many hadronic processes. This model describes quite well the antihyperon polarization data obtained in proton-nucleus collisions, and now we extended it to study nucleus-nucleus collisions, with a very good accord. Theoretical results obtained with other models will also be discussed. The perspectives of hyperon and antihyperon polarization at LHC is another subject of interest. References: [1] STAR Collaboration: B. I. Abelev et al., Phys. Rev. C, 76, (2007) 024915. [2] C. C. Barros Jr. and Y. Hama, Phys. Lett. B., 699, 74 (2011). [3] C. C. Barros Jr., to be submitter soon.

Speaker: Prof. Celso Barros (Universidade Federal de Santa Catarina)

Slides Hyperon_Polarization_in_Heavy_ion_Collisions.pdf Hyperon_Polarization_in_Heavy_ion_Collisions.pptx

49 eRHIC: A Precision Tool for Studying Nuclear Structure.

eRHIC is envisaged as a next-generation upgrade to the RHIC facility, involving the addition of a high-intensity, high-energy electron beam, to deliver a broad programme of both nuclear and spin physics. e+A collisions at eRHIC will answer open questions about the distribution and interactions of gluons within nuclei, something not possible with any existing machine. They will allow precise probing of the nuclear initial state, due to both the absence of the final-state interactions present in nucleus-nucleus collisions, which obscure details of the initial state, and the precise reconstruction of the initial event kinematics afforded by an electron beam. Exclusive diffractive collisions will allow the nuclear gluon distribution to be imaged in detail, while the use of nuclear beams will provide access to the regime of low-x gluon saturation, for which there are presently only tantalising hints. Meanwhile, polarised electron and proton beams will yield unmatched detail in characterising the spin structure of nucleons. I will summarise the features of the eRHIC accelerator itself and some of the key measurements to be made, with a focus on in its e+A physics programme.

Speaker: Thomas Burton (BNL)

Slides burtonERhicSqmJuly2013.pdf

50 LHeC

Speaker: Paul Richard Newman (University of Birmingham (GB))

Slides SQM13.pdf

Poster Session

Wednesday, 24 July

Plenary 6

Convener: Boris Hippolyte (Institut Pluridisciplinaire Hubert Curien (FR))

51 Strange Quark Matter (Astro)

Speaker: Mark Alford (W)

Slides sqm.pdf

52 Traveling Through the Universe: Back in Time to the Quark-Gluon Plasma Era

Speaker: Johann Rafelski (University of Arizona (US))

Paper 1310SQM_JR_Sub2.pdf

Slides 1307SQM_Universe_Talk.pdf

53 Quark-gluon plasma phenomenology from the lattice

The interquark potential in charmonium states is calculated for the first time in both the zero and non-zero temperature phases from a first-principles lattice QCD calculation. Simulations with two dynamical quark flavours were used with temperatures T in the range 0.4Tc 􏰇 T 􏰇 1.7Tc, where Tc is the deconfining temperature. The correlators of point-split operators were analysed to gain spatial information about the charmonium states. A method, introduced by the HAL QCD collaboration and based on the Schr ̈odinger equation, was applied to obtain the interquark potential. We find a clear temperature dependence, with the central potential becoming flatter (more screened) as the temperature increases.

Speaker: Chris Allton (Swansea University)

Slides talk-v2.pdf

10:30 Break

Plenary 7

Convener: Klaus Werner

54 Role of fluctuations in detecting the QCD phase transition

We will discuss the role of fluctuations of conserved charges and the Polayakov loop, as well as their probability distributions, to detect deconfinement and chiral phase transition or their remnants.

Speaker: Krzysztof Redlich (University of Wroclaw (PL))

Slides Redlich_SQM_2013.pdf Redlich_SQM_2013.ppt

55 Holographic descriptions of dense quark matter

The properties of quark matter at high density and strong coupling remain largely intractable using conventional tools. We review how the tools of string theory and holography can pave the way towards a better understanding of general properties of such phases of matter using a holographically dual gravitational picture. We will describe some recent results within such a framework that point at novel critical scaling behaviour emerging as long-wavelength descriptions of high density systems.

Speaker: Prem Kumar (Swansea University)

56 Coarse Graining in Hydrodynamics and Effects of Fluctuations

The success of hydrodynamic description of the collective flow dynamics in relativistic heavy ion collisions is often understood as the realization of local thermal equilibrium during the phase of QGP. However, the scale of locality is not clear. Some of such basic questions about the hydrodynamic approach to relativistic heavy-ion collisions are discussed aiming to clarify how far we can go with such an approach to extract useful information on the properties and dynamics of the QCD matter created. We emphasize the importance of the coarse graining scale required for the hydrodynamic modeling which determines the space-time resolution and the associated limitations of collective flow observables. We show that certain kinds of observables can indicate the degree of non homogeneity of the initial condition under less stringent condition than the local thermal equilibrium subjected to the coarse-graining scale compatible to the scenario. The origin of viscosity associated with the coarse-graining procedure is also discussed.

Speaker: Takeshi Kodama (Universidade Federal do Rio de Janeiro)

Slides SQM2013_Kodama.pdf

Excursion

Thursday, 25 July

Plenary 8

57 Hydrodynamic models of particle production - p-Pb collisions

The modelling of the collective expansion in A-A and p-A collisions and the role of initial conditions for the fireball are discussed. Predictions for spectra of strange baryons and mesons are presented. Di-hadron correlations between identified particles, resulting from flow and charge correlations are estimated in the model.

Speaker: Piotr Bozek

Slides bozeksqm.pdf

58 Interpretation of strange hadron production at LHC

We present a highly successful description of all available particle yields in Pb–Pb collisions at 2.76 TeV measured by the ALICE experiment as a function of centrality. We find that our fit of π, K, p, Ξ and Ω within the framework of non–equilibrium statistical hadronization model is consistent with previous fits of Au–Au data at 62.4 and 200 GeV from RHIC. The more precise LHC data strongly support chemical non-equilibrium model and chemical freeze-out temperature of T ≃ 140 MeV. The high entropy content of the fireball suggests additional entropy production mechanism increasing with centrality, yet to be understood. Strangeness content of the fireball shows saturation already for small systems at LHC energy suggesting a chemically equilibrated QGP as a source of hadrons. Our results show universal hadronization conditions of the particle source, represented by critical pressure P ≃ 80 MeV/fm3 , energy density ε ≃ 0.5 GeV/fm3 and entropy density σ ≃ 3.3 fm-3. These conditions apply to both RHIC and LHC for all collision centralities, in which the fit procedure works.

Speaker: Michal Petran (Czech Technical University (CZ))

Slides Petran-SQM2013.pdf

59 Confronting LHC data with the statistical hadronization model

Speaker: Johanna Stachel (Ruprecht-Karls-Universitaet Heidelberg (DE))

Slides 3.sqm2013_stachel.pdf

10:30 Break

Plenary 9

Convener: Paolo Giubellino (Universita e INFN (IT))

60 Latest LHCb results from the pA data

With a unique forward acceptance, and excellent vertexing and particle identification capability, LHCb is well-placed to make important contributions to heavy ion physics through measurements performed using data taken during pA and Ap collisions. The first studies of these data will be presented. These include measurements of particle multiplicity and studies of strange and charmed particle and onia production.

Speaker: Liang Zhong (Tsinghua University (CN))

Slides lzhong_sqm.pdf

61 p-Pb Results from ALICE with an Emphasis on Centrality Determination

Speaker: Dr Andreas Morsch (CERN)

Slides SQM2013_morsch_1.pdf

62 Identified hadron production in pp and pPb collisions with CMS

Spectra of identified charged hadrons measured in pPb collisions at the LHC at $sqrt{s_{NN}} = 5 $TeV are presented. Charged pions, kaons, and protons in the transverse-momentum range p_T = 0.1-1.7 GeV/c and for central rapidities are identified via their energy loss in the CMS silicon tracker. The average p_T increases rapidly with the mass of the hadron and the charged-particle multiplicity of the event. The fully corrected transverse momentum spectra and integrated yields are compared to pp data at various collision energies and to several Monte Carlo event generators.

Speakers: Eric Andrew Appelt (Vanderbilt University (US)), The CMS Collaboration (CMS)

Slides SQM2013_Birmingham_Appelt_v2.pdf

Beam Energy Scan

Convener: Evgeni Kolomeitsev (Matej Bel University)

63 The QCD phase transition in a fully dynamical model of heavy-ion collisions

Experimental signals for a possible QCD critial point and first-order phase transition are strongly influenced by the rapid nonequilibrium dynamics during a heavy-ion collision. In order to estimate and understand these effects we study the cooling through the phase transition within a nonequilibrium chiral fluid dynamics model. The order parameters for the chiral and deconfinement transition are explicitly propagated, taking into account dissipation and fluctuation stemming from the interaction with a quark-antiquark fluid. In studies of single events, we demonstrate for the first time in a realistic dynamical study the formation of domains in net-baryon density at the first-order transition. This shows that nonequilibrium effects are strong enough to favor spinodal decomposition. As a possible experimental signal we find a clear enhancement of higher flow harmonics. For the detection of the critical point it is crucial that the relevant signal survives the rapid dynamics. Critical slowing down is manifestly incorporated in our model and influences the growth of the correlation length. We demonstrate in an event-by-event analysis that fluctuations of the volume-averaged order parameters develop a clear peak around the critical point in a dynamical system like a heavy-ion collision.

Speaker: Christoph Herold (Frankfurt Institute for Advanced Studies)

Slides SQM_Herold.pdf

64 Study of freeze-out dynamics in STAR at RHIC beam energy scan program

The STAR experiment at RHIC has collected data at various collision energies in its beam energy scan (BES) program to study the QCD phase diagram. The BES program covers a large part of the QCD phase diagram in terms of temperature (T) versus baryon chemical potential ($\mu_B$). The collected data set can be used to study the kinetic and chemical freeze-out dynamics. The kinetic and chemical freeze-out parameters can be extracted using the transverse momentum ($p_{T}$) spectra of hadrons and the total yields within the framework of statistical model assuming thermal equilibrium. We report the centrality and energy dependence of chemical freeze-out parameters (temperature, baryon and strangeness chemical potential, and strangeness saturation factor) in Au+Au collisions at $\sqrt{s_{NN}} =$ 7.7, 11.5, 27, and 39 GeV. The chemical freeze-out conditions are obtained by comparing the experimentally measured ratios of particle yields at mid-rapidity, which includes $\pi^{\pm}$, $\emph{K}^{\pm}$, $\emph{p}$, $\bar{\emph{p}}$, $K^{0}_{S}$, $\Lambda$, $\bar{\Lambda}$, $\Xi^{-}$, and $\bar{\Xi^{+}}$ to those obtained from the statistical-thermal model calculations (THERMUS). The kinetic freeze-out parameters of temperature and radial collective flow are obtained by fitting the invariant pT differential yields of the produced hadrons, as a function of transverse momentum using a Blast Wave model.

Speaker: Ms Sabita Das (Brookhaven National Laboratory, USA and Institute of Physics, India)

Slides sqm2013_Sabita.ppt

65 Beam energy scan using a viscous hydro+cascade model

We employ the up-to-date version of viscous Hydro-Kinetic Model (vHKM) based on 3+1D viscous hydrodynamic code coupled to UrQMD hadron cascade. Following the experimental program at BNL RHIC, we perform a similar "energy scan" in the model, and study the collision energy dependence of charged and identified hadron spectra, flow coefficients and femtoscopic radii. For this aim the equation of state for finite baryon density from Chiral model coupled to Polyakov loop is employed for hydrodynamic stage. 3D initial conditions from UrQMD model are used to study gradual deviation from boost-invariant picture for midrapidity interval justified for top RHIC energies and above. In particular, we address the question, how far down in the collision energy the well-established at RHIC and LHC energies picture of (viscous) hydro+cascade can be applied at BES. Based on the constraints from the NA49/CERES data the model may also be used to provide the predictions for the measurements in RHIC BES program.

Speaker: Dr Iurii Karpenko (Frankfurt Institute for Advanced Studies)

Slides sqm13.pdf

66 The elliptic flow and the shear viscosity of the QGP within a kinetic approach

We investigate within a parton cascade approach at fixed $\eta/s$ ratio the effect of a temperature dependent $\eta/s(T)$ at three different beam energies from RHIC for Au+Au at $\sqrt(s)=$62.4, 200 GeV to LHC energies for Pb+Pb at $\sqrt(s)=$2.76 TeV. An important result is that for the different beam energies considered the suppression of the elliptic flow due to the viscosity of the medium has different contaminations coming from the cross-over (hadronic) or QGP phase depending on the average energy of the system. In particular, we observe that at LHC the elliptic flow is less contaminated by the hadronic phase allowing a better study of the QGP properties. We will show that the observed scaling of $v_{2}(p_{T})$ from RHIC to LHC energies implies a fall and rise of $\eta/s(T)$ and allow to put a first constraint on $\eta/s(T)$. [1] S. Plumari, A. Puglisi, F. Scardina, V. Greco, Phys.Rev. C86 (2012) 054902. [2] S. Plumari, A. Puglisi, M. Colonna, F. Scardina, V. Greco, J.Phys.Conf.Ser. 420 (2013) 012029.

Speaker: Dr SALVATORE PLUMARI (UNIVERSITY OF CATANIA, ITALY)

Slides PLUMARI_TALK_SQM2013.pdf

67 Higher moments of net kaon multiplicity distributions at RHIC energies for the search of QCD Critical Point

The Relativistic Heavy-Ion Collider (RHIC), at BNL, has started its beam energy scan(BES) program by colliding heavy-ions covering a wide range in baryonic chemical po- tential. One of the main goals of this beam energy scan program is to locate the critical point which is postulated to lie at the end of the phase transition boundary between partonic and hadronic matter. Finite temperature lattice QCD calculations at baryon chemical potential $μ_{B}$ = 0 suggest a crossover above a critical temperature from a system with hadronic degrees of freedom to a system where the relevant degrees of freedom are quarks and gluons. Several QCD based calculations find the quark-hadron phase transition to be first order at large $μ_{B}$ . The point in the QCD phase plane (T vs $μ_{B}$ ) where the first order phase transition ends is the QCD critical point (CP). In a static, infinite medium, the correlation length (ξ) diverges at the CP. ξ is related to various moments of the distributions of conserved quantities such as net baryons, net charge, and net strangeness[1]. Typically variances ($σ^{2} = <(∆N)^{2}>$ ; ∆N = N − M ;where M is the mean) of these distributions are related to ξ as $σ^{2}$ ≃ $ξ^{2}$ [2]. Finite size and time effects in heavy-ion collisions put constraints on the values of ξ. A theoretical calculation suggests ξ ≃ 2 − 3 fm for heavy-ion collisions[2, 3]. It was recently shown that higher moments of distributions of conserved quantities, measuring deviations from a Gaussian, have a sensitivity to CP fluctuations that is better than that of $σ^{2}$, due to a stronger dependence on ξ[2, 3, 4]. The numerators in skewness $(S=<(∆N )^{3}>/σ^{3})$ go as $ξ^{4.5}$ and kurtosis $(k = [<(∆N)^{4}>/σ^{4}] − 3) go as $ξ^{7}$ [5].

Speaker: Mr Amal( for the STAR collaboration) Sarkar (Indian Institute of Technology Bombay, Mumbai)

Slides SQM2013_Amal.pdf

68 Probing the QCD phase diagram with the measurements of $\phi$-meson production and elliptic flow in the heavy-ion collision at STAR.

The main goal of the Beam Energy Scan (BES) program at Relativistic Heavy Ion Collider (RHIC) is to study the QCD phase diagram by varying the colliding beam energy. Due to the small hadronic interaction cross-section, the yield and elliptic flow of the $\phi$ meson are primarily controlled by the partonic interaction in the relativistic heavy-ion collisions[1,2]. Therefore, the $\phi$ meson can be considered as a good probe for the phase boundary study in the BES program at RHIC. At top RHIC energy ($\sqrt{s_{NN}}$= 200 GeV) in Au + Au collisions, the $\phi$ meson has played an important role to establish that matter formed in such collisions is partonic. The number-of-constituent-quark scaling of the elliptic flow of the $\phi$ meson[3], enhancement in the yield of the $\phi$ meson in Au + Au collisions relative to $p + p$ collisions[4], and the ratio of yield of the $\Omega$ baryon to the yield of the $\phi$ meson as a function of $p_{T}$[3] have been the key measurements. We will present transverse momentum dependence of yield and elliptic flow of the $\phi$ meson in Au + Au collisions at $\sqrt{s_{NN}}$= 7.7 - 200 GeV data collected in the years 2010 and 2011 by the STAR experiment. We will discuss the number-of-constituent-quark scaling of $\phi$-meson $v_{2}$, nuclear modification factor $R_{CP}$ and ratio of yield of the $\Omega$ baryon to the yield of the $\phi$ meson as a function of $p_{T}$. The implications of these results on the quark-hadron phase transition will be also discussed. References: [1] Md. Nasim, B. Mohanty and N. Xu, Phys. Rev. C 87 (2013) 014903. [2] B. Mohanty and N. Xu, J. Phys. G 36 (2009) 064022. [3] B. I. Abelev et al. [ STAR Collaboration], Phys. Rev. Lett. 99 (2007) 112301. [4] B. I. Abelev et al. [ STAR Collaboration], Phys. Lett. B 673, (2009) 183.

Speaker: Mr Nasim Md (NISER)

Slides SQM2013_nasim.pdf

Hard Probes

Convener: George Stephans (Massachusetts Inst. of Technology (US))

69 Electroweak boson production in heavy-ion collisions with CMS

The Compact Muon Solenoid (CMS) is fully equipped to measure leptonic decays of electroweak probes in the high multiplicity environment of nucleus-nucleus collisions. Electroweak boson production is an important benchmark process at hadron colliders. Precise measurements of W and Z production in heavy-ion collisions can help to constrain nuclear PDFs as well as serve as a standard candle of the initial state in PbPb collisions at the LHC energies. The inclusive and differential measurements of the Z boson yield in the muon decay channel will be presented, establishing that no modification is observed with respect to next-to-leading order pQCD calculations, scaled by the number of incoherent nucleon-nucleon collisions. Measurements of the yield of W bosons decaying into a muon and a(n anti)neutrino as a function of centrality, and the W charge asymmetry as a function of rapidity show no modifications beyond the expected effect of isospin when compared to pp collisions.

Speakers: Michael Gardner (University of California Davis (US)), The CMS Collaboration (CMS)

Slides Electroweak_Measurement.pdf

70 Jet production and structure in pp, p-Pb and Pb-Pb collisions measured by ALICE

One of the major goals of jet and high pT measurements in heavy-ion collisions is the quantification of the medium-modified fragmentation of hard scattered partons. Here, the aim in the reconstruction of jets, as compared to single particle measurements, is to gain a larger sensitivity to the possibly modified structure of the parton shower. It aims at the understanding of the detailed mechanisms of in medium energy loss and their relation to transport properties of the medium itself. The measurement of the jet production cross section in three different colliding systems pp (QCD vacuum), pPb (cold nuclear matter), and PbPb (hot partonic system) allows to extract the modification of jets in the hot and dense medium with respect to two references. Different angular resolutions (jet radii) allows for the a first estimate of the degree of angular modification in the medium. In the context jets spectra and the measurement of a modified fragmentation compared to the vacuum reference it is important that the underlying event background and its fluctuations is treated consistently for all colliding systems. We will present recent ALICE results on the jet production in pp, p-Pb and Pb-Pb collisions and discuss their sensitivity on a modified jet fragmentation process beyond a leading parton energy loss.

Speaker: Marta Verweij (Wayne State University (US))

Slides JetsALICEMVerweij.pdf

71 Investigation of Mach cones and the corresponding two-particle correlations in a microscopic transport model

Using a microscopic transport model we investigate the evolution of conical structures originating from the supersonic jet through the hot matter and dense matter of ultra-relativistic heavy-ion collisions. We found that the Mach cone angle is influenced by the source term properties, energy deposition and viscosity. While in a static medium a possible double-peak structure is overshadowed by the diffusion wake and head shock, it turns out that in central heavy-ion collisions due to the radial flow of the expanding medium a double-peak structure is visible. On the one hand this is mainly contributed from Mach cones propagating into the opposite direction of the radial flow, while on the other hand deflected jets may also contribute to a final double-peak structure. The corresponding double-peak structure is observed insofar the shear viscosity over entropy density ratio is sufficiently small, while a larger dissipation destroys any kind of Mach cone and/or double-peak structure.

Speaker: Ioannis Bouras (University of Frankfurt a.M.)

Slides bouras_SQM2013.pdf

72 ATLAS high-pT measurements in lead-lead collisions

Measurements of high-pT processes in lead-lead collisions can provide insight on the physics responsible for the quenching of jets in the quark gluon plasma. Results will be presented from ATLAS measurements of single jet suppression, both inclusively and as a function of the azimuthal angle of the jets with respect to the elliptic flow plane, single jet fragmentation, and gamma-jet correlations. Theoretical comparisons to and implications of the results will be discussed. Also, results will be presented for measurements of photon, Z, and W production that provide essential tests on calculations of hard scattering rates and nuclear geometry.

Speaker: Zvi Citron (Weizmann Institute of Science (IL))

Slides sqm.pptx

73 Tomography of QGP with jet asymmetries

Within a multi-phase transport (AMPT) model, the transverse momentum asymmetries for $\gamma$-jet and di-jet are studied in Pb+Pb collisions at $\sqrt{s_{_{\rm NN}}}$ = 2.76 TeV. A large asymmetry is produced by strong interactions between jets and partonic matter rather than by hadronic interactions only. It is demonstrated that final hadronic processes such as hadronization and hadronic rescatterings have little effects on the formed asymmetry. The asymmetry evolution functions are extracted to disclose that final asymmetry is driven by both initial asymmetry and partonic jet energy loss, which is consistent with jet energy loss in a hot and strongly interacting partonic medium. The imbalance or asymmetry ratio, e.g. $x_{j\gamma}$ or $A_{J}$, is sensitive to both production position and passing direction of $\gamma$-jet and di-jet, which could enable a detail tomographic study on the formed partonic matter by selecting different asymmetry ratio ranges experimentally. References: [1]Guo-Liang Ma, arXiv: 1302.5873 [2]Guo-Liang Ma, arXiv: 1304.2841

Speaker: Guo-Liang Ma (Shanghai INstitute of Applied Physics (SINAP), CAS)

Slides MaGuoliang_sqm2013_final.pdf

74 Appearance of a quark matter phase in hybrid stars

Appearance of a quark matter in the core region of hybrid stars is the main issue in such compact stars because the central density of the star is sufficiently high for the nuclear matter to undergo a further change into other exotic phase which consist of hyperons and quarks. Therefore a quark matter is expected in the core region but many theoretical calculation suggest that the inner structures of the star are strongly depend on the equation of states (EOS) of the matters. However the EOS for the high density matter is still not clear and recent several observations indicate the restrictions of the EOSs, theoretical studies should try to elucidate the EOSs in the high density and/or temperature. It is believed that the crust region of the stars consist of nucleus and nuclear matter and therefore the inner region of the stars should have hadron-quark mixed phase. We study the hadron-quark mixed phase with taking into account the finite-size effects and find that the mixed phase should be restricted to a narrower region, therefore a quark matter phase should appear in the central region[1]. Many studies show that the inner structures would affect macroscopic phenomena of the star, for instance, the quark core would give a new cooling curve[2]. References: [1] T. Endo, Phys. Rev. C 83, 068801 (2011). [2] R. Negreiros, V.A. Dexheimer and S. Schramm, Phys. Rev. C85, 035805(2012).

Speaker: Prof. Tomoki Endo (Kagawa National College of Technology)

Slides sqm2013_endo.pdf

Heavy Flavour 2

Convener: Ramona Vogt (University of California at Davis)

75 Towards the dynamical study of heavy-flavour quarks in the Quark-Gluon-Plasma

The aim of this project is to study the properties of the QGP produced in relativistic heavy-ion collisions (HIC) using heavy quarks - charm and beauty (c, b) - as penetrating probes. The heavy quarks (and correspondingly charm and beauty mesons) are considered to be one of the best probes for such a study since due to their large mass they are produced dominantly by hard processes during the early stage of the reaction when the QCP is formed; traversing the plasma they do not come into equilibrium with the environment since their interaction with the partons is probably not strong enough. Our study of charm dynamics in HIC is based on the existing microscopic PHSD (Parton-Hadron-String Dynamics) transport approach [1] which incorporates explicit partonic degrees-of-freedom in terms of strongly interacting quasiparticles (quarks and gluons) in line with an equation-of-state from lattice QCD as well as the dynamical hadronization and hadronic collision dynamics in the final reaction phase. The evaluation of scattering cross sections of heavy quarks with the QGP quasiparticles represents the first step of this study. In our contribution, we will present the elastic scattering cross section of heavy quarks with partons in vacuum and in the QGP medium [2] at finite temperature and chemical potential. We will, furthermore, present our evaluation of the transport coefficients, employing this cross section and discuss the dynamical collisional energy loss of heavy quarks in the QGP. Our results show clearly the effect of finite temperature and chemical potential on the perturbative heavy quark cross section, transport coefficients and collisional energy loss [2, 3]. [1] W. Cassing, and E. L. Bratkovskaya, ``Parton-Hadron-String Dynamics: an off-shell transport approach for relativistic energies’’, Nucl. Phys. A831 (2009) 215-242. [2] H. Berrehrah, P.B. Gossiaux, J. Aichelin, E. Bratkovskaya, W. Cassing and M. Bleicher, “Collisional processes of heavy quarks in vacuum and in the QGP medium”, in preparation. [3] H. Berrehrah, E. Bratkovskaya, W. Cassing, P.B. Gossiaux and J. Aichelin, “Interaction rates, dynamical collisional energy loss and transport coefficients of heavy quarks in vacuum and in the QGP medium”, in preparation.

Speaker: Dr Hamza Berrehrah (FIAS)

Slides SQM2013_H.Berrehrah.pdf

76 Heavy vs. light flavor energy loss within a partonic transport model

The full space-time evolution of gluons, light and heavy quarks in ultra-relativistic heavy-ion collisions is studied within the partonic transport model Boltzmann Approach to MultiParton Scatterings (BAMPS). We discuss in detail for all flavors the influence of elastic and radiative energy loss with a running coupling. Radiative processes, in particular, are implemented through an improved version of the Gunion-Bertsch matrix element, which is derived from comparisons to the exact result, explicitly taking finite heavy quark masses into account. Consequently, we present results of this updated version of BAMPS and compare them to experimental data at RHIC and LHC. In detail, the nuclear modification factor and elliptic flow of charged hadrons, heavy flavor electrons as well as muons, D mesons, and non-prompt J/psi are discussed. The latter two are especially sensitive to the mass difference of charm and bottom quarks. Furthermore, we make predictions where no data is available yet.

Speaker: Jan Uphoff (Goethe University Frankfurt)

Slides jan_uphoff_sqm13.pdf

77 Open charm measurements in $p+p$ collisions at STAR

Heavy quarks are expected to be created from initial hard scatterings. Due to their large masses, their production can be described by perturbative QCD. The charm production cross section measurement in $p+p$ collisions provides an important baseline to further exploring the QCD medium. At STAR, charm quarks are measured through Open Charm Mesons and Non-photonic Electrons (electrons from semi-leptonic decays of charmed and bottom hadrons, NPE) production analysis. In this talk, we will present the STAR results of open charm hadron and NPE productions at mid-rapidity in $p+p$ collisions at $\sqrt{s}$ = 200 and 500 GeV. Open charm mesons were reconstructed directly via hadronic decay channels with daughter particles identified by STAR Time Projection Chamber (TPC) and Time Of Flight (TOF) detectors and NPE yields were calculated by subtracting photonics electrons from inclusive electrons identified by TPC and Electromagnetic Calorimeter. These measurements are compared to theoretical model calculations and physics implications will be discussed.

Speaker: David Tlusty (NPI ASCR)

Slides SQM2013_Tlusty.pdf

78 Measurement of electrons from heavy-flavour decays in Pb-Pb collisions at √sNN = 2.76 TeV with ALICE

Measurement of electrons from heavy-flavour decays in Pb-Pb collisions at √sNN = 2.76 TeV with ALICE Deepa Thomas (Utrecht University) for the ALICE Collaboration The measurement of heavy-flavour (charm and beauty) production in ultra-relativistic heavy-ion collisions is an important probe to study the properties of the high temperature and density medium created in such collisions. Heavy quarks are useful to study the mechanism of parton energy loss, which is expected to be sensitive to the colour charge and mass of the parton. One approach to study heavy-flavour production is the measurement of electrons from semi-leptonic decays of heavy-flavour hadrons. With the ALICE detector at the LHC, electrons are identified using several detectors in the central rapidity region, namely the Time Of Flight detector, the Time Projection Chamber, the Electromagnetic Calorimeter, and the Transition Radiation Detector. In this contribution we present the nuclear modification factor (RAA) which is the ratio of the yield in Pb-Pb collisions to the yield in binary scaled pp collisions, azimuthal anisotropy and elliptic flow (v2) which is the second Fourier coefficient of particle azimuthal distribution of heavy-flavour decay electrons as a function of transverse momentum. These two observables are sensitive to the interactions of c and b quarks with the medium. Further insight into the interaction of heavy quarks with the dense medium can be obtained by measuring azimuthal angular correlations of heavy-flavour decay electrons and charged hadrons in Pb-Pb collisions. We will also discuss results from this analysis.

Speaker: Deepa Thomas (University of Utrecht (NL))

Slides SQMProc-Deepa.pdf

79 D meson nuclear modification factor and v2 in Pb-Pb collisions

D meson nuclear modification factor and v2 in Pb-Pb collisions Elena Bruna (INFN Torino) for the ALICE Collaboration The remarkable heavy-flavour results from RHIC and LHC show that heavy quarks are affected by the strongly coupled medium created in heavy-ion collisions at high energies. A way to characterize the properties of such a hot and dense medium is to quantify to what extent the medium influences the propagation of the particles through it, and how this varies for different parton species. Given their large mass, heavy quarks are produced in the early stages of a heavy-ion collision and their abundance is not expected to change throughout the evolution of the system. Therefore, they behave as self-generated probes that carry information of the medium by losing energy via subsequent interactions. The high precision tracking, particle identification, and excellent vertexing capabilities of ALICE allow for measurements of heavy-flavoured particles in a wide momentum region. We present the ALICE results on open heavy-flavour, focusing on the production of D0, D+, D*, and Ds mesons measured via the exclusive reconstruction of their hadronic decays displaced from the interaction vertex. These measurements benefit from the large statistics of Pb-Pb collisions collected in 2011. The results on the nuclear modification factor RAA for D mesons indicate a suppression of their yield in central collisions relative to binary-scaled pp collisions in a large momentum range. The comparison to the RAA of non-prompt J/Psi (measured by CMS) indicates a difference in the suppression of charm and beauty at high pT, as expected according to the predicted mass hierarchy in energy loss models. The measurement of the azimuthal anisotropy of charmed mesons in semi-peripheral events is also discussed. The observed non-zero second Fourier harmonic v2 (elliptic flow) for 2<pT<6 GeV/c, together with the different D0 RAA along the event plane and orthogonally to it, could originate from the collective motion and path-length dependence of the energy loss of charm quarks. The results discussed above are also compared to various energy-loss models.

Speaker: Elena Bruna (Universita e INFN (IT))

Slides ebruna_SQM13_v6.pdf

80 Open-charm production as a function of charged-particle multiplicity in pp collisions at √s = 7 TeV with ALICE

Open-charm production as a function of charged-particle multiplicity in pp collisions at √s = 7 TeV with ALICE Renu Bala, for the ALICE Collaboration University of Jammu, Jammu Heavy quarks (charm and beauty) are an effective tool to investigate the properties of the Quark-Gluon Plasma in heavy ion collisions as they are produced in initial hard scattering processes and as they experience all the stages of the medium evolution. The measurement of heavy-flavour production cross sections in pp collisions at the LHC, besides providing a reference for heavy-ion studies, allows one to test perturbative QCD calculations. A brief review of ALICE results on the production of heavy flavoured hadrons measured from fully reconstructed decay topologies in pp collisions at √s = 2.76 and 7 TeV will be presented. Furthermore, heavy-flavour production was also studied as a function of the particle multiplicity in pp collisions. This allows to investigate the interplay between hard and soft QCD processes and to study the role of multi-parton interactions. It is interesting to remark that the highest multiplicities reached in pp collisions at 7 TeV are similar to those measured in Cu-Cu collisions at RHIC energies. A measurement of the inclusive J/Psi yield as a function of the charged-particle pseudorapidity density was performed by the ALICE Collaboration at the LHC in pp collisions at √s = 7 TeV. An approximately linear increase of the J/Psi yield with increasing multiplicity was observed. In this context, the study of the yield of D mesons as a function of the charged-particle multiplicity could provide a deeper insight into charm-quark production in pp collisions. We will present the first results obtained for prompt D0, D+, and D*+ mesons using hadronic decay channels at midrapidity in pp collisions at √s = 7 TeV as a function of the charged-particle multiplicity. The prompt D meson yields as a function of multiplicity are measured in different pT intervals. These yields will be compared to the results obtained for inclusive and non-prompt J/Psi.

Speaker: Dr Renu Bala (University of Jammu (IN))

Slides renu_SQMNew.pdf

16:00 Break

16:00 Break

16:00 Break

Future

Convener: Jun Takahashi (Universidade Estadual de Campinas (BR))

81 Prospects for heavy flavour measurements with the ALICE inner tracker upgrade

Prospects for heavy flavour measurements with the ALICE inner tracker upgrade C.Terrevoli, University and INFN of Cagliari, on behalf of the ALICE Collaboration The ALICE detector is designed to investigate the properties of the hot and dense plasma of quarks and gluons, formed at the extreme energy densities reached in Pb-Pb collisions at LHC. Among the probes useful to investigate this medium, heavy quarks play a special role because they are produced in the very initial stage of the collisions and they carry information about the properties of the traversed medium. In particular, an accurate measurement of heavy flavour provides information on fundamental properties of the medium as transport coefficients, the thermalization and hadronization mechanisms. Interesting results have been obtained in the first three years of data-taking at the LHC, but there are still open questions, which would require measurements beyond the present capabilities of the ALICE apparatus. Among them, the most interesting are the measurement of the nuclear modification factor (R_AA) and anisotropy of the azimuthal distributions of charm and beauty mesons down to transverse momentum below 1 GeV/c. Another completely unexplored field is the measurement of the production of heavy flavour baryons, like the Lambda_c and Lambda_b, that can bring insight on the heavy quark hadronization mechanism in the presence of a partonic medium. At present such measurements are limited by the resolution of the inner tracking system, which, for instance, is not sufficient to measure in Pb-Pb collisions the production of Lambda_c baryons, that have a mean proper decay length of only 60 μm. Another limitation of the present ALICE central barrel detectors to the measurement of heavy flavours at low momentum, is the maximum achievable readout rate, which prevents the full exploitation of the luminosity expected to be delivered by LHC after the Long Shutdown 2. An upgrade of the inner tracking system based on today’s frontier technologies has been recently approved. The new detector will improve by a factor 2-3 the current performance in pointing and momentum resolution, providing in addition a high tracking efficiency down to very low transverse momentum. Moreover, a faster readout, for all the central barrel detectors, will allow for a data collection rate, in Pb-Pb collisions, a factor 100 larger than at present, and this will contribute to enhance the ALICE physics performance very significantly. In this contribution, we will present an overview of the inner tracker upgrade and the expected physics performance for heavy flavour measurements.

Speaker: Cristina Terrevoli (Universita e INFN (IT))

Slides ITSUpgradeSQM2013_ter.pdf

82 NA61/SHINE experiment upgrade with vertex detector for open charm measurements

A feasibility study for D0 meson (Open charm) measurements via its decay into two daughter particles, D0 → K+ π−, in a central Pb­-Pb collisions at SPS energies will be presented. To generate the physical input we use AMPT (A MultiPhase Transport model) event generator. We employed the GEANT4 application to describe particle transport through the experimental setup. The study is done assuming the NA61/SHINE experimental setup supplemented with a future vertex detector that allows for precise track vertex reconstruction at the target proximity. This detector will be used ultimately to measure open charm mesons in nucleus­nucleus collisions at energies accessible at the CERN-­SPS. The simulation results show that this measurement is feasible. The presentation will discuss the obtained results focusing on the predicted yields of D0 mesons and the possibilities of differential analysis. It will also address the issue of vertex detector optimization and the emphasis will be put on the prospect of the development of a vertex detector based on CMOS technology.

Speaker: Mr Yasir Ali (Jagiellonian University)

Slides SQM2013-YAli.pdf

83 The NICA project at JINR Dubna

The NICA (Nuclotron-based Ion Collider fAcility) project is now under the realization stage at the Joint Institute for Nuclear Research (JINR, Dubna). The main goal of the project is an experimental study of hot and dense strongly interacting matter in heavy ion collisions at centre-of-mass energies √s_NN = 4 - 11 GeV (NN-equivalent) and the average luminosity of 10E27 cm-2 s-1 for Au(79+) in the collider mode (NICA collider). In parallel, fixed target experiments at the upgraded JINR superconducting synchrotron Nuclotron are carried out with extracted beams of various nuclei species up to Au(79+) with maximum momenta 13 GeV/c (for protons). The project also foresees a study of spin physics with extracted and colliding beams of polarized deuterons and protons at the energies up to √s = 26 GeV (for protons). The proposed program allows to search for possible signs of the phase transitions and critical phenomena as well as to shed light on the problem of nucleon spin structure. General design and construction status, physical program of the NICA complex is presented.

Speakers: Prof. Alexander Sorin (Joint Institute for Nuclear Research), Prof. Vladimir Kekelidze (Joint Institute for Nuclear Research)

Slides Sorin_SQM2013_Birmingham_25_07_2013.pdf Sorin_SQM2013_Birmingham_25_07_2013.pptm

84 Status and Challenges of the Compressed Baryonic Matter (CBM) Experiment at FAIR

The CBM experiment is one of the four scientific pillars of the Facility for Antiprotons and Ion Research (FAIR) in Darmstadt, Germany. Its discovery potential – complementary to heavy-ion experiments at colliders – is based on high-luminosity ion beams. This enables access to extremely rare probes such as charmed particles, vector mesons, multi-strange hyperons or even double hypernuclei with high statistics. However, 3rd generations readout systems and detectors are required to handle the large interaction rates (up to 10 MHz for Au+Au) with sufficient precision and bandwidth. In this contribution we will outline the unique CBM physics program and its relation to other, existing (RHIC-BES, SPS-NA61) or future (NICA-MPD) heavy-ion experiments in a similar energy range (2-35 AGeV). We will further elaborate on the demands and challenges, which are imposed by the high collision rates and event multiplicities on the different CBM detectors systems

Speaker: Prof. Hans Rudolf Schmidt (University of Tuebingen)

Slides CBM_Status_SQM_2013.pdf

Resonances

Convener: Christina Markert (University of Texas (US))

85 Beam Energy Dependence of Strange Hadron Production from STAR at RHIC

Strange hadron production is believed to be sensitive to parton dynamics in nucleus-nucleus collisions, in particular, the strange quark production rate and its subsequent evolution in the dense partonic medium depend on the beam energy and the net baryon density. We will present STAR measurements of $K_{s}$, $\Lambda$, $\Xi$, $\Omega$ at mid-rapidity from Au+Au collisions at the beam energies of 7.7, 11.5, 19.6, 27 and 39 GeV from the RHIC Beam Energy Scan (BES) program. We investigate the strangeness enhancement and ratios of anti-baryon to baryon yields as a function of beam energy at RHIC. Nuclear modification factors and ratios of baryon to meson yields will also be discussed. Implications on collision dynamics due to the increase in the baryon chemical potential at low beam energy and constraints on chemical freeze-out parameters will also be discussed.

Speaker: Feng Zhao (University of California, Los Angeles)

Slides SQM_FengZhao.pdf

86 Resonance Production in sqrt(s) = 7 TeV pp collisions with ALICE.

The study of pp collisions at LHC energies is important not only as a baseline for future analysis in heavy-ion events at ALICE but also aiding in the calibration of QCD inspired models for LHC energies. ALICE has measured the rho0, Sigma* and Csi* resonances in pp collisions at sqrt(s) = 7 TeV. This presentation will give an overview of the obtained results including transverse momentum spectra, ratios between the yields of these resonances and stable particles and <pT>.

Speaker: Mr Graham Richard Lee (University of Birmingham (GB))

Slides Res_production_7tev.pdf

87 Hadronic resonances in heavy-ion collisions at ALICE

Properties of the hadronic phase of high-energy heavy-ion collisions can be studied by measuring the ratios of hadronic resonance yields to the yields of longer-lived particles such as charged pions and kaons. These ratios can be used to study the strength of re-scattering effects, the chemical freeze-out temperature, and the lifetime between chemical and kinetic freeze-out. The restoration of chiral symmetry during the early hadronic phase or near the phase transition may lead to shifts in the masses and increases in the widths of hadronic resonances. The ALICE collaboration has measured the spectra, masses, and widths of the K(892)0 and phi(1020) resonances in Pb–Pb collisions at sqrt(s_NN) = 2.76 TeV. These results, including R_CP, R_AA, mean transverse momenta, and the ratios of the integrated resonance yields to non-resonance hadron yields, will be presented and compared to results from other collision systems and theoretical predictions. Studies of resonance properties in p–Pb collisions provide a baseline measurement to which heavy-ion measurements can be compared; the status of the measurements of the phi(1020) meson in this collision system will be also reported.

Speaker: Anders Garritt Knospe (University of Texas (US))

Slides Knospe130725_v8.pdf Knospe130725_v8.pptx

88 Low mass vector meson production in pp and Pb-Pb collisions measured with ALICE at the LHC

Low mass vector meson (ρ, ω, ϕ) production provides key information on the hot and dense state of strongly interacting matter produced in high-energy heavy-ion collisions. Among them, strangeness production can be accessed through the measurement of ϕ meson production. The detection of vector mesons through their decay in dileptons has the advantage, with respect to hadronic decays, that the decay products are not in uenced by nal state interactions. The ALICE apparatus at the LHC can access vector mesons produced at forward rapidity (2.5 < y < 4) through their decays in muon pairs. We present results on vector meson production in pp and Pb-Pb collisions at c.m. energy of 2.76 TeV per nucleon pair. The ϕ cross section is measured in pp collisions. In Pb-Pb collisions, a measurement of the ϕ/ρ + ω ratio and of the ϕ nuclear modication factor as a function of the collision centrality is obtained. The status of the analysis in p-Pb and Pb-p at c.m. energy of 5.02 TeV per nucleon pair is also shown.

Speaker: Alessandro De Falco (Universita e INFN (IT))

Slides adf-SQM13.pdf

Strangeness 2

Convener: Krzysztof Redlich (University of Wroclaw (PL))

89 Elliptic ow of Λ, Ξ and Ω in 2.76 A TeV Pb+Pb collisions

The elliptic flow of common hadrons (pions, kaons, and protons) are developed in both the QGP and the hadronic phase and are sensitive to the viscosity of the evolving fireball. For a precise extraction of the QGP viscosity from these flow data, Hybrid model calculations that combine hydrodynamic simulations of the expending QGP fluid with microscopic descriptions of the re-scattering hadronic gas are required. Multi-strange hadrons ($\phi$, $\Omega$, etc) with smaller hadronic cross sections are expected to decouple from the system earlier and might directly probe the QGP viscosity. In this talk, we will systematically study the elliptic flow of different multi-strange hadrons to test the QGP viscosity extracted from the elliptic flow of common hadrons. We will also extract effective early decoupling temperatures for different multi-strange hadrons through comparing the full hybrid model simulations and the pure hydrodynamic simulation with early decoupling.

Speaker: Huichao Song (Peking U)

Slides Strange-SQM2013.pdf Strange-SQM2013.pptx

90 Multi-strange baryon production in Pb-Pb and pp collisions at √sNN = 2.76 TeV with the ALICE experiment at the LHC

Measurement of the production of strange and multi-strange particles is a fundamental tool in the investigation of the hot and dense QCD matter created in ultra-relativistic nucleus-nucleus collisions, as there is no net strangeness content in the initial colliding system. Multi-strange baryons are measured in the ALICE apparatus through the reconstruction of the cascade topology of their weak decays into charged hadrons, exploiting the tracking and particle identification capabilities of the central barrel detectors. The increased production of (multi-)strange (anti-)baryons in A-A collisions with respect to normal hadronic interactions (known as strangeness enhancement) and their nuclear modification factor RAA as a function of the transverse momentum and collision centrality are the main subjects of this contribution. Results in Pb-Pb collisions at √sNN = 2.76 TeV for five centrality intervals and in pp collisions at the same centre-of-mass energy will be presented and compared with the corresponding lower energy nucleus-nucleus measurements.

Speaker: Domenico Colella (Universita e INFN (IT))

Slides Multistrange_baryons_ALICE_SQM13.pdf

91 K0s and Lambda Production in ALICE

The production of the Λ and 𝐾0s hadrons at the LHC can be measured through the reconstruction of their weak decay topologies with only charged particles in the final state. The tracking and particle identification capabilities of the ALICE detector allow us to measure the spectra of these particles over a wide transverse momentum range (0.4 < pT < 12 GeV/c), and to precisely determine the behaviour of the baryon-to-meson ratio Λ/K0S. Transverse momentum spectra and production yields at mid-rapidity for Λ and K0S will be presented for sqrt(s_NN) = 2.76 TeV Pb-Pb collisions as a function of centrality. The evolution of the Λ/K0S ratio will be discussed, in comparison with corresponding results in pp collisions at the LHC and in sqrt(s) = 200 GeV Au-Au collisions at RHIC.

Speaker: Luke David Hanratty (University of Birmingham (GB))

Slides ldh_LLK0Results_SQM2013_10.pdf

92 Strangeness baryon to meson ratio

We present a model to compute baryon and meson transverse momentum distributions, and their ratios, in relativistic heavy ion collisions. Our model allow to compute the probability to form colorless bound states of either two or three quarks as functions of the evolving density during the collision. The qualitative differences of the baryon to meson ratio for different collision energies and for different particle species can be associated to the different density dependent probabilities when accounting for the combinatorial factors which in turn depend on whether the quarks forming the bound states are heavy or light. We compare to experimental data and show that we obtain a good description up to intermediate values of pt.

Speaker: Eleazar Cuautle Flores (Universidad Nacional Autonoma (MX))

Slides Cuautle_sqm2013.pdf

Conference Dinner

Friday, 26 July

Plenary 10

Convener: Dr Andreas Morsch (CERN)

93 Jet Quenching and Heavy Quarks

Jet quenching is a cornerstone of the heavy-ion physics program at the LHC. I review the current understanding of jet quenching in terms of a QCD shower evolution being modified by the surrounding medium, leading to copious medium induced radiation, and I outline the evidence for this picture from the light parton sector. Conceptually, the QCD shower description should also be relevant for heavy quarks, but with several important modifications. I discuss why heavy quark jets (especially in the limit of small E_jet/m_q) do not reflect the same physics as light quarks and give an overview over current attempts to explain how the observed behaviour of heavy quark jets can be understood.

Speaker: Thorsten Renk (University of Jyväskylä)

Slides trenk-SQM.pdf

94 Jet results from PbPb and pPb collisions with CMS

We present a review of recent experimental results on jet production and properties in heavy-ioncollisions by the CMS Collaboration, with emphasis on jet-quenching and heavy quark jet production. These studies include various parton energy loss phenomena (dijet and photon-jet energy imbalance, jet shapes and fragmentation functions), a study of heavy quark jet production using b quark tagging technique, and measurements of jet pT and pseudorapidity distributions. All of the presented results utilize the high statistics pPb and PbPb data collected at the LHC.

Speakers: George Stephans (Massachusetts Inst. of Technology (US)), The CMS Collaboration (CMS)

Slides Stephans_CMS_Jets_SQM13_v3.pdf

95 Results on angular correlations with ALICE

Angular correlations are a sensitive probe of the transport properties of the system produced in heavy-ion collisions. Angular correlations measured in p--Pb have recently revealed intriguing features as well. In this talk, we will review the latest results on charged and identified particle correlations obtained with the ALICE detector at the LHC in both Pb--Pb and p--Pb events.

Speaker: Dr Panos Christakoglou (NIKHEF (NL))

Slides CorrelationsAlice.Christakoglou.SQM.pdf

10:30 Break

Plenary 11

Convener: Nu Xu (LBNL)

96 Measurement of azimuthal anisotropy of hadrons in Au+Au collisions from the beam energy scan program by the PHENIX experiment at RHIC

Large azimuthal anisotropy of particle emission in non-central heavy ion collisions has been has been clearly observed in heavy ion collision at RHIC since 2001. The elliptic flow as given by the second term of the Fourier series for the azimuthal distribution of particles with respect to the event plane is believed to carry information on the initial geometrical anisotropy. One of the early observations was that in Au+Au collisions at 200 GeV, the elliptic flow of hadrons scales with number of constituent quarks, which may be an indication for flow of constituent quarks in a QGP phase. An event plane detector, RxP, was installed in the PHENIX experiment for 2007 data taking period, in order to improve the resolution of the event plane determination. The RxP detector also has allowed PHENIX make accurate measurements of elliptic flow at lower collision energies, where the transition of a QGP might be detected. The primary goal of beam energy scan program at RHIC energy is to search for the boundary between two phases of QCD matter: a gas of hadrons, and the Quark Gluon plasma. The latest elliptic flow measurement for identified hadrons in Au+Au collisions from the beam energy scan program at PHENIX will be presented and discussed.

Speaker: Yoshimasa Ikeda (for the PHENIX collaboration, Riken)

Slides sqm2013.pdf

97 Status and Physics Opportunities of STAR Heavy Flavor Tracker and Muon Telescope Detector Upgrades

The STAR Collaboration will complete the Heavy Flavor Tracker (HFT) and the Muon Telescope Detector (MTD) upgrades by 2014. HFT utilizes the state-of-art active thin pixel detector technology, which will greatly enhance STAR physics capability by measuring heavy quark collectivity and correlations via the topological reconstruction of charmed hadrons over a wide momentum range. MTD is based on the long Multi-Gap Resistive Plate Chamber detector technology designed to measure muons penetrating the bulk of other detectors and the magnet yoke. It will enable STAR to study di-muon and electron-muon correlations and enhance heavy quarkonium studies. With the addition of these upgrades, STAR is well suited to perform precise measurements of production as well as correlations of rare probes (heavy flavors, dileptons) to systematically investigate the quark-gluon plasma properties at RHIC. For the ongoing Run 13 63% of the MTD has been installed and data have been taken. And prototype PXL sectors (30% coverage) have also been installed and commissioned. Anticipated physics results and current status of these upgrades will be reported.

Speaker: Dr Hao Qiu (Lawrence Berkeley National Laboratory)

Slides Status_and_physics_opportunities_of_STAR_HFT_and_MTD_upgrades.pdf

98 Strangeness balance in HIC

We discuss the strangeness production in heavy-ion collisions at SIS-FAIR-NICA energies and the role of doubly and triply strange baryons for testing the strangeness balance in a collision event. The minimal statistical model is applied, in which the total strangeness yield is fixed by the observed K+ multiplicity. Exact strangeness conservation in each collision event is explicitly preserved. This implies for instance that Xi baryons can be released only in events where two or more kaons are produced. The influence of in-medium effects and centrality bias on the strange particle production is analyzed. The puzzling enhancement of Xi yields is discussed and arguments in favor of the Xi production in direct reactions are given. Various mechanisms for Xi productions are reviewed.

Speaker: Evgeni Kolomeitsev (Matej Bel University)

Slides Kolomeitsev-SQM13.pdf Kolomeitsev-SQM13.ppt

Quarkonia/Heavy Flavour

99 Quarkonia production and suppression in heavy ion collisions at STAR

Suppression of quarkonia production in high energy nuclear collisions relative to proton-proton collisions, due to the Debye screening of the quark-antiquark potential, was proposed as a signature of the formation of the Quark-Gluon Plasma (QGP). Measurement of production of various quarkonia states can provide insight into thermodynamic properties of the QGP since different states have different binding energy and therefore disassociate at different temperature. However, there are other effects that may affect the observed production, such as cold nuclear matter effects, final state nuclear absorption and statistical coalescence of quark-antiquark pairs. Study of quarkonia production for different colliding systems, collision energies and centralities can help to disentangle the interplay of these mechanisms and to understand the medium properties. In this talk we report on recent STAR results on J/psi and Upsilon production and suppression at midrapidity in Au+Au collisions at RHIC. We present J/psi invariant yield and nuclear modification factor as a function of centrality and transverse momentum at $\sqrt{s_{NN}}$ = 200, 62.4 and 39 GeV and discuss the energy dependence of the J/psi production. We also present $\Upsilon$ nuclear modification factor in Au+Au and d+Au collisions at 200 GeV calculated using high statistics p+p data taken in 2009.

Speaker: Daniel Kikola (Warsaw University of Technology)

Slides SQM_2013_STAR_Quarkonia.pdf

100 Free energy versus internal energy potential for heavy quark systems at finite temperature

Using the QCD sum rule with its operator product expansion reliably estimated from lattice calculations for the pressure and energy density of hot QCD matter, we calculate the strength of the $J/\psi$ wave function at origin and find that it decreases with temperature when the temperature is above the transition temperature. This result is shown to follow exactly that obtained from the solution of the Schr\"odingier equation for a charm and anticharm quark pair using the free energy from lattice calculations as the potential and is in sharp contrast to that using the deeper potential associated with the internal energy, which shows an enhanced strength of the $J/\psi$ wave function at origin. Our result thus has resolved the long-standing question of whether the free energy potential or the internal energy potential should be used in analyzing the spectrum of heavy quark systems at finite temperature.

Speaker: Su Houng Lee (Yonsei University)

101 Heavy quark quenching from RHIC to LHC: MC@HQ generator compared to experiements

Recently, we have proposed a microscopic approach for the quenching and thermalisation of heavy quarks (HQ) in URHIC [1-4], assuming that they interact with light partons through both elastic and radiative processes evaluated by resorting to some parameterization of the running coupling constant, while those partons are spatially distributed along hydrodynamical evolution of the hot medium. This approach is able to explain successfully several observables measured at RHIC and LHC, such as the nuclear modification factor and the elliptic flow of open heavy flavor mesons and non-photonic single electrons. The diffusion coefficient of heavy quarks in the quark gluon plasma -- a fundamental property of this state of matter -- can thus be extracted and compared with recent lattice calculations. In this contribution, we would like to provide a general overview of our MC@HQ event generator and discuss the predictions of our model for D and B mesons and lepton production in URHIC and confront them with experimental results obtained so far by the various collaborations at RHIC and LHC. A particular focus will be devoted to the impact of the backgound medium, using several hydrodynamical schemes available nowadays. Perspectives for future observables like correlations will be proposed. [1] P.B. Gossiaux, J. Aichelin, Phys. Rev. C78, 014904 (2008), [hep-ph/0802.2525]. [2] P.B. Gossiaux, R. Bierkandt, J. Aichelin, Physical Review C79 (2009) 044906. [3] P.B. Gossiaux, V. Guiho, J. Aichelin, J. Phys. G: Nucl. Part. Phys. 37 (2010) 094019. [4] P.B. Gossiaux et al., accepted for publication in Nuclear Physics A [arXiv:1209.0844].

Speaker: Pol Gossiaux (Subatech)

Slides SQM_gossiaux.pdf

102 Jet suppression at LHC: theory vs. experiment

Suppression of light and heavy flavor observables is one of the most important probes in studying the properties of QCD matter created at RHIC and LHC experiments. We will here provide the most up-to-date light and heavy flavor suppression predictions for the available (2.76TeV) and the upcoming (~5TeV) Pb+Pb collisions at LHC. The predictions are based on our recent improvements in the energy loss calculations that take into account: i) theoretical formalism which includes finite magnetic mass [1], ii) finite size dynamical QCD medium [2], iii) numerical procedure which includes path-length and multi-gluon fluctuations [3]. We recently showed that these improvements may provide a reasonable explanation of the "Heavy flavor puzzle at RHIC" [3], while predictions for the available and the upcoming LHC data will be presented here. [1] M. Djordjevic and M. Djordjevic, Physics Letters B 709, 229 (2012). [2] M. Djordjevic, Phys. Rev. C 80, 064909 (2009) (highlighted in: M Gyulassy, Physics 2, 107 (2009)). [3] M. Djordjevic, Phys. Rev. C 85, 034904 (2012).

Speaker: Dr Magdalena Djordjevic (Institute of Physics Belgrade, University of Belgrade, Serbia)

Slides MDjordjevicSQM2013.pdf MDjordjevicSQM2013.pptx

103 Semi-classical approach to J/psi suppression in high energy heavy-ion collisions

Quarkonia suppression in heavy ion collisions has been investigated as a probe to Quark-Gluon Plasma properties and was indeed observed at SPS. However, the saturation of the suppression observed at RHIC and then is decrease at LHC has triggered the interest of our community and leads to consider alternate schemes as those based on sequential suppression in a stationary medium. In our contribution, we study the evolution of a quark-antiquark pair in a cooling isotropic QGP medium. For this purpose we use two different approaches: a) the semi-classical evolution equation proposed by C. Young and E. Shuryak [1] and b) a quantum evolution equation of the open QQbar system, better suited to study the evolution of bound states. We consider for both approaches different color screening potentials, temperature scenarios at RHIC and LHC, charmonium and bottomonium bound states, and thermalisation processes. A comparison to previous results [1][2][3] is finally carried out. [1] C. Young and E. Shuryak, Phys. Rev. C 79, 034907 (2009) [2] Y. Akamatsu and A. Rothkopf, Phys.Rev. D85 (2012) 105011 [3] M. Strickland and D. Bazow, Nuclear Physics A 879, 25-58 (2012)

Speaker: Mr Roland Katz (SUBATECH)

Slides Quantum_and_semi-classical_approches_to_quarkonia_suppression_Katz_SQM2013.pdf

104 Studies of Onia and Strangeness Production in Proton-proton Collisions at LHCb

Studies of strangeness and quarkonia production in the forward region provide important input to the understanding of QCD models in a kinematical range where they have large uncertainties. The LHCb experiment has collected a dataset corresponding to an integrated luminosity of about 3 fb-1 in proton-proton collisions at sqrt(s)= 7 and 8 TeV, as well as smaller samples recorded with other LHC operating modes. We present the latest studies of the production of kaons, Lambda baryons, and quarkonia states.

Speaker: Nicholas Brook (University of Bristol (GB))

Paper brook.pdf

Slides LHCb_SQM.pdf

Thermal models/Hydro

105 Production of Strange, Non-Strange Particles and Hypernuclei in an Excluded-Volume Model

Recently, we proposed a thermodynamically consistent excluded-volume model for a hot, dense hadron gas (HG). We confront our model calculations on various properties of HG, multiplicity and ratios of various strange and non-strange particles in the entire range of temperature and baryon densities with the other models and experimental data and we find that our model describes the experimental data suitably in comparison to other models. Furthermore, we numerically show that our model respects causality while most of the excluded-volume models suffer from this deficiency. Our model describes the production of strange particles satisfactorily but fails in describing multistrange particles (i. e. \phi, \Omega etc.) production. So, we need another kind of mechanism to describe the production of multistrange particles successfully. We test our model in getting the rapidity as well as transverse mass spectra of various strange and non-strange hadrons. We find that our model with the effect of flow describes the experimental data on transverse mass spectra and rapidity distributions very well. Further, we analyze the production of light nuclei, hypernuclei and their anti-nuclei over a broad energy range from Alternating Gradient Synchrotron (AGS) to Large Hadron Collider (LHC) energies using our excluded-volume model. We again find a good agreement between our model calculations and experimental data. Thus, we conclude that our excluded-volume model is a proper equation of state (EOS) for hot and dense HG.

Speaker: Swatantra Kumar Tiwari (Banaras Hindu University)

Slides SQM_2013_UK.pdf

106 Event-by-event correlation between medium flow and jet flow

It is well-known that a nonzero initial spatial eccentricity in a heavy-ion collision is reflected in the final anisotropic flow of the bulk medium. Jets traversing a spatially anisotropic medium also develop momentum anisotropy (at fixed pT) through path length dependence of energy loss. For smooth initial conditions, bulk and jet flow anisotropy coefficients are naturally related. However, more realistic initial condition models include large fluctuations in the initial transverse profile of the medium with "hot spots" that induce a nontrivial bulk and jet response in momentum space. We present results on the correlation between the bulk and jet flow anisotropy pattern in A+A at RHIC and LHC, from a calculation that combines covariant transport theory for the bulk medium evolution with jet energy loss for high-pT light and heavy-flavor production.

Speaker: Denes Molnar

107 Strangeness at high temperatures

Appropriate combinations of up to fourth order cumulants of net strangeness fluctuations and their correlations with net baryon number and electric charge fluctuations, obtained from ab-initio Lattice QCD calculations, have been used to probe the strangeness carrying degrees of freedom at high temperatures. For temperatures up to the chiral crossover separate contributions of strange mesons and baryons can be well described by an uncorrelated gas of hadrons. Such a description breaks down immediately after the chiral crossover region, suggesting that the deconfinement of strangeness takes place at the chiral crossover. On the other hand, the strangeness carrying degrees of freedom inside the quark gluon plasma can be described by a weakly interacting gas of quarks only for temperatures larger than twice the chiral crossover temperature. In the intermediate temperature window these observables show considerably richer structures, indicative of the strongly interacting nature of the quark gluon plasma.

Speaker: Christian Schmidt (University of Bielefeld)

Slides sqm13v2.pdf

108 Systematic Properties of the Tsallis Distribution: Energy Dependence of Parameters

Changes in the transverse momentum distributions with beam energy are studied using the Tsallis distribution as a parameterization. The dependence of the Tsallis parameters q, T and the volume are determined as a function of beam energy. The Tsallis parameter q shows a weak but clear increase with beam energy with the highest value being approximately 1.15. The Tsallis temperature and volume are consistent with being independent of beam energy within experimental uncertainties.

Speaker: Prof. Jean Cleymans (University of Cape Town)

Slides cleymans_sqm2013.pdf

109 Elliptic Flow from fKLN Initial Conditions

A current goal of relativistic heavy ion collisions experiments is the search for a Color Glass Condensate as the limiting state of QCD matter at very high density. In viscous hydrodynamics simulations, a standard Glauber initial condition leads to estimate $4\pi \eta/s \sim 1$, while a Color Glass Condensate modeling leads to at least a factor of 2 larger $\eta/s$. Within a kinetic theory approach based on a relativistic Boltzmann-like transport simulation, we point out that the out-of-equilibrium initial distribution proper of a Color Glass Condensate reduces the efficiency in building-up the elliptic flow. We study the dynamical impact of Color Glass Condensate at both RHIC and LHC energies. Our main result at RHIC energy is that the available data on $v_2$ are in agreement with a $4\pi \eta/s \sim 1$ also for Color Glass Condensate initial conditions, opening the possibility to describe self-consistently also higher order flow, otherwise significantly underestimated, and to pursue further the search for signatures of the Color Glass Condensate. [1] M. Ruggieri, F. Scardina, S. Plumari, V. Greco, arXiv:1303.3178 [nucl-th]. [2] S. Plumari, V. Baran , M. Di Toro, G. Ferini, V. Greco, Phys.Lett. B689 (2010) 18-22.

Speaker: Dr francesco scardina (INFN Catania)

Slides scardina_talk_sqm2013.pdf

p-A collisions

110 Measurement of D meson production in p-Pb collisions with the ALICE detector

Measurement of D meson production in p-Pb collisions with the ALICE detector Grazia Luparello (NIKHEF and Utrecht University) for the ALICE Collaboration The ALICE Collaboration has measured the production of prompt $\rm{D^0}$, $\rm{D^{+}}$ and $\rm{D^{*+}}$ mesons in Pb-Pb and pp collisions by fully reconstructing their hadronic decays. A large suppression of D meson yield in the most central Pb-Pb collisions with respect to the binary-scaled pp yield was observed in a broad $p_{\rm{T}}$-range. This effect is consistent with the energy loss of charm quarks while they traverse the hot and dense medium formed in such collisions. To come to a quantitative understanding of these results, it is important to disentangle hot nuclear matter effects from initial-state effects due to cold nuclear matter, such as modification of the parton distribution functions in the nucleus, in particular nuclear shadowing, and saturation effects. Between January and February 2013, ALICE collected a data sample of minimum bias p-Pb collisions at $\sqrt{s_{NN}}$=5.02 TeV. The study of the D meson production in this collision system, where a hot nuclear medium is not expected to be formed, will quantify the role of initial-state effects. In this talk, the first results on D meson production in p-Pb collisions obtained in the $\rm{D}^0 \rightarrow \rm{K}^- \pi^{+}$, $\rm{D}^+ \rightarrow \rm{K}^- \pi^+ \pi^+$, $\rm{D}^{\star +} \rightarrow \rm{D}^0 \pi^{+}$ decay channels in the central rapidity region will be presented.

Speaker: Grazia Luparello (NIKHEF (NL))

Slides Luparello_SQM2013.pdf

111 Measurement of electrons from heavy-flavour hadron decays in pp and p-Pb collisions with ALICE

Measurement of electrons from heavy-flavour hadron decays in pp and p-Pb collisions with ALICE at the LHC Markus Heide for the ALICE Collaboration, WWU Münster Charm and beauty quark production in hadronic collisions occurs mostly in initial parton scattering processes with high virtuality. The measurement of heavy-flavour decay electrons in pp collisions with the ALICE detector represents therefore a crucial test of pQCD predictions on heavy-flavour production. At the same time, it provides an essential reference for measurements in Pb-Pb collisions, where heavy quarks are important probes for the investigation of energy-loss mechanisms in the Quark-Gluon Plasma. The influence of cold nuclear matter effects (e.g. gluon saturation, nuclear shadowing, and the Cronin effect) on the electron spectrum can be inferred from the analysis of p-Pb collisions. ALICE makes use of its central barrel detectors TPC, TOF, TRD, and EMCal to identify electrons at mid-rapidity. From these, background electrons from decays of light mesons and photon conversions are subtracted, based on respective preceding ALICE measurements. The resulting yield of heavy-flavour hadron decay electrons is measured down to a transverse momentum of 0.5 GeV/c. In addition, the high precision vertex reconstruction with the Inner Tracking System allows for a separate determination of the electron yield from B-meson decays, either from displaced single electrons or from secondary vertices. Alternatively, the contribution from beauty-hadron decays to the inclusive spectrum of electrons from heavy-flavour hadron decays is determined via the azimuthal angular correlation between electrons and charged hadrons. Measurements of the pT-differential electron production cross sections from inclusive heavy-flavour hadron and B-meson decays in pp collisions at √s = 2.76 and 7 TeV will be presented. Furthermore, a first look will be taken at the inclusive electron spectrum from heavy-flavour hadron decays in p-Pb collisions at √sNN = 5.02 TeV.

Speaker: Markus Ansgar Heide (Westfaelische Wilhelms-Universitaet Muenster (DE))

Slides SQM13_Heide_HF.pdf

112 D meson-hadron angular correlations in pp and p-Pb collisions with ALICE at the LHC

Fabio Filippo Colamaria, for the ALICE Collaboration ALICE measured a significant suppression of D-meson production in a wide momentum range in central Pb-Pb collisions with respect to the expectation based on the cross section measured in pp collisions, scaled by the number of nucleon-nucleon collisions. This effect can be, at least partially, attributed to the energy loss by charm quarks through the interaction with the Quark Gluon Plasma formed in such collisions. The comparison of angular correlations between charmed mesons and charged hadrons produced in pp, p-Pb and Pb-Pb collisions can give insight into the mechanisms through which charm quarks lose energy and help to spot possible modifications of their hadronisation induced by the presence of the medium. The analysis of pp and p-Pb data and the comparison with predictions from pQCD calculations, besides constituting the necessary baseline for the interpretation of Pb-Pb data, can provide relevant information on charm production and fragmentation processes. We will present a study of azimuthal correlations between D0, D+, and D* mesons and charged hadrons in pp collisions at √s = 7 TeV and p-Pb collisions at √s = 5.02 TeV. D mesons were reconstructed from their hadronic decays at central rapidity and in the transverse momentum range 2 ≤ pT ≤ 16 GeV/c and were correlated to charged hadrons reconstructed in the pseudorapidity range |η|<0.8. Perspectives for the measurement in Pb-Pb collisions at √s = 2.76 TeV will be also discussed.

Speaker: Fabio Filippo Colamaria (Universita e INFN (IT))

Slides Colamaria_-_D-hadron_correlations_ALICE.pdf

113 Inclusive J/psi production in p-Pb collisions with ALICE at the LHC

Production of charmonia, bound state of c and cbar quarks, is an intense research activity, both experimentally and theoretically. In addition, the peculiar properties of some of the charmonium states, like their small size (< 1 fm) and strong binding energy (several hundred MeV), make them ideal probes of the strongly interacting matter, the so-called Quark-Gluon Plasma (QGP), formed in heavy-ion collisions. ALICE is dedicated to the study of QGP properties in heavy-ion collisions at the LHC. It measured J/psi suppression in Pb-Pb collisions at the energy of 2.76 TeV per nucleon pair. At the beginning of 2013, p-Pb collisions at the energy of 5.02 TeV per nucleon pair have been studied at the LHC, in order to measure the effects related to cold nuclear matter which, for charmonia, include gluon shadowing (or gluon saturation), energy loss and nuclear absorption. Their evaluation is important in order to be able to disentangle, in Pb-Pb collisions, hot and cold nuclear matter effects. First results on the J/psi production in p-Pb collisions, in the dimuon decay channel at forward rapidity, will be presented and compared to theoretical models.

Speaker: Igor Lakomov (Universite de Paris-Sud 11 (FR))

Slides Lakomov_SQM2013.pdf

114 Two-particle correlations in p-Pb collisions at the LHC with ALICE

The double ridge structure previously observed in Pb-Pb collisions has also been recently observed in high-multiplicity p-Pb collisions at \sqrt{s_{NN}} = 5.02 TeV. These systems show a long-range structure (large separation in ∆η) at the near- (∆ϕ = 0) and away-side (∆ϕ = π) of the trigger particle. In order to understand the nature of this effect the two-particle correlation analysis has been extended to identified particles. Particles are identified up to pT values of 4GeV/c using the energy loss signal in the Time Projection Chamber detector, complemented with the information from the Time of Flight detector. This measurement casts a new light on the potential collective (i.e. hydrodynamic) behavior of particle production in p-Pb collisions.

Speaker: Leonardo Milano (CERN)

Slides LM_SQM2013.pdf

115 Transverse Momentum Distributions of Identified Particles in p–Pb collisions at sqrt(s_NN) = 5.02 TeV

Recent measurements of di-hadron correlations in p–Pb collisions at sqrt(s_NN) = 5.02 TeV revealed a double-ridge pattern, reminiscent of the one observed in Pb–Pb collisions. This raises the question of the possible existence of collective effects in high multiplicity p–Pb collisions. Further insight into the observed phenomena can be gained by studying the evolution of spectral shapes with the particle mass and particle ratios as a function of charged-particle density. Transverse momentum (pT) distributions of hadrons have been measured at midrapidity (0. < yCMS < 0.5). Particles are reconstructed with the central barrel detectors over a wide transverse momentum range (0 GeV/c up to 6 GeV/c) and different identification techniques are used. Primary charged particles (pi±,K±, p and ¯p) are identified by their specific energy loss (dE/dx) and time-of-flight. Weakly decaying particles (K0s, Lambda and antiLambda) are identified by their characteristic decay topology. Particle-production yields, spectral shapes and particle ratios are measured in several multiplicity classes and are compared with results obtained in Pb–Pb collisions at sqrt(s_NN) = 2.76 TeV at the LHC.

Speaker: Jonas Anielski (Westfaelische Wilhelms-Universitaet Muenster (DE))

Slides 2013.07.25_SQMjonas_final.pdf 2013.08.06_SQMjonas_final.pdf

16:00 Break

16:00 Break

16:00 Break

Hypernuclei

116 Recent results on ultra-peripheral Pb-Pb and p-Pb collisions at the ALICE experiment

The electromagnetic fields surrounding the protons and nuclei, accelerated by the LHC, lead to very large cross sections for photon-induced processes. This makes the LHC the world's most powerful collider not only for protons and lead ions but also for photon-photon and photon-hadron collisions. These interactions can be studied in ultra-peripheral collisions, where the impact parameters are larger than the sum of the nuclear radii and hadronic interactions are suppressed. Exclusive vector meson production in heavy-ion collisions is expected to probe the nuclear gluon density, for which there is considerable uncertainty at low values of Bjorken-x. The first LHC measurement on UPC was recently carried out with the ALICE experiment [1-2]. During the 2010 and 2011 Pb+Pb runs at the LHC, as well as in the p+Pb run in 2013, ALICE collected data using dedicated triggers to select ultra-peripheral collisions. These triggers were based on the Muon spectrometer, the Time-of-Flight detector, the Silicon Pixel detector, and the VZERO scintillator array. Information from other detectors was also used in the analysis, mainly to ensure the exclusivity of the reaction. The photoproduction cross section of J/ψ meson at forward and central rapidities in Pb-Pb collisions have been measured [1-2]. These results have been compared to model calculations and their implications for nuclear gluon shadowing will be discussed in this talk. Furthermore, first results on exclusive J/ψ photoproduction in p+Pb collisions will be given. Other ongoing analyses on ultra-peripheral collisions will also be discussed. 1. B.Abelev,etal.(ALICECollaboration) Phys.Lett.B718(2013)1273-1283 2. E.Abbas,etal.(ALICECollaboration) http://arxiv.org/abs/arXiv:1305.1467

Speaker: Daniel Tapia Takaki (Universite de Paris-Sud 11 (FR))

Slides

• DanielTapiaTakaki-SQM2013-v3.pdf
• jdtt-SQM-Birmingham2013-v4.pdf
• SQM-ExternalReview-1.pdf

117 Production of antinuclei and hypernuclei in a relativistic heavy-ion collisions

The production of light nuclei, hypernuclei and their antiparticles in relativistic energy heavy ion collisions are explored within a relativistic Hagedorn Resonance Gas (HRG) model. In the HRG model the unknown heavy-mass resonance spectra is characterized by an exponentially growing Hagedorn states that undergo sequential binary emission of lighter resonances and stable hadrons till all the energy is exhausted. Binary collision between the particles during space-time evolution may regenerate the resonance thereby maintaining detailed balance. The production yield of (hyper)nuclei and exotic multistrange hypernuclear objects will be presented over a wide collision energy range from the AGS/BNL to the LHC/CERN. We find abundant antinuclei production and their reconstruction thus becomes feasible at the RHIC and LHC energies where the net baryon densities are relatively small. At center-of-mass energy of 8-20 GeV, relatively large baryon density and moderate strangeness provide the ideal energy regime for the observation of multistrange hypernuclear objects.

Speaker: Prof. Subrata Pal (Tata Institute of Fundamental Research, Mumbai)

118 Production of hypernuclei in Pb-Pb collisions at √sNN = 2.76 TeV with ALICE at the LHC

In high-energy heavy-ion collisions hyperon-baryon bound systems, called hypernuclei, can emerge from the hot and dense fireball region of the reaction. Their production yield can be estimated employing two distinct models: they can be formed via the coalescence of nucleons and hyperons produced in the collision or they can be produced directly in the hadronisation process. The study of the production yield of hypernuclei at the LHC energy can help to distinguish between the two models. Results on (anti-) hypertriton production in Pb–Pb collisions at √sNN = 2.76 TeV, obtained by ALICE at the LHC, are reported. The (anti-) 3LH signal is extracted exploiting its mesonic decay ( 3 LH → 3He + π ) , via the topological identification of secondary vertices and the study of the invariant mass distributions of (3He, π) pairs. The (anti-) 3LH production yield will be presented and compared to stable nuclei and theoretical models. An assessment of (anti-) 3 LH lifetime will also be discussed.

Speaker: Ramona Lea (Universita e INFN (IT))

Slides SQM_RamonaLea.pdf

119 Search for exotic hyper-matter and measurement of nuclei with ALICE at the LHC

The high collision energies reached at the LHC lead to significant production yields of light anti-nuclei and hyper-matter in proton-proton and, in particular, Pb-Pb collisions. The excellent particle identification capabilities of the ALICE apparatus, based on the specific energy loss in the Time Projection Chamber and time-of-flight measurement, allow for the detection of these rarely produced particles. Further the Inner Tracking System gives the possibility to separate primary nuclei from those coming from the decay of heavier systems. This offers the unique opportunity to search for exotica like the bound state of a Lambda and a neutron which would decay into deuteron and pion, or the bound states of two Lambda’s. The results of these searches will be compared to the production of light (anti-)nuclei and with the expectations from thermal and coalescence models.

Speaker: Benjamin Doenigus (GSI - Helmholtzzentrum fur Schwerionenforschung GmbH (DE))

Slides sqm2013_bd_final.pdf

Quarkonia/Heavy Flavour

120 Measurements of J/psi to ee with ALICE at the LHC

The ALICE detector provides excellent capabilities to study quarkonium production at the Large Hadron Collider (LHC). Quarkonia, bound states of heavy (charm or bottom) quark anti-quark pairs such as the J/psi, are expected to be produced by initial hard processes. Thus they will provide insight into the earliest and hottest stages of A-A collisions where the formation of a Quark-Gluon Plasma (QGP) is expected. Furthermore, high-precision data from pp collisions represent an essential baseline for the measurement of nuclear modifications in heavy-ions and serve also as a crucial test for several models of quarkonium hadroproduction. In addition, the study of pA collisions allows to investigate nuclear modifications due to cold nuclear matter effects. In ALICE, J/psi have been measured in pp, p-Pb and Pb-Pb down to pT = 0 via their di-electron decay channel in the central barrel (|y| < 0.9). Results on the nuclear modification factor (RAA) at central rapidities in Pb-Pb collisions at sqrt{sNN} = 2.76 TeV, as well as a first look into p-Pb data at sqrt{s} = 5.02 TeV will be shown and their implications discussed. A separation of the prompt and non-prompt components is also possible down to a pT of the J/psi of a few GeV/c, which allows to study the beauty hadron nuclear modification factor down to almost zero pT.

Speaker: Fiorella Fionda (Universita e INFN (IT))

Slides SqmSlides_afterCCreview.pdf

121 Charmonium production measurements in Pb-Pb collisions with ALICE at the LHC

ALICE (A Large Ion Collider Experiment), one of the four main experiments at the Large Hadron Collider (LHC), was designed and built to perform dedicated research on heavy-ion collisions to study the Quark-Gluon Plasma (QGP), a deconfined state of strongly interacting QCD matter. As heavy flavours are produced on a very short time-scale in the initial hard scattering processes, they can be used to characterize the hot and dense medium formed in high-energy heavy-ion collisions through their modified yield as compared to pp collisions. In particular, the production c-cbar bound states was proposed as a thermometer of the created medium. In ALICE, charmonium production is measured via the dielectron and dimuon decay channels at central (|y| < 0.9) and forward (2.5 < y < 4) rapidity, respectively. In this talk, final results on charmonium production in Pb-Pb collisions at sqrt{s_{NN}} = 2.76 TeV will be presented and compared to theoretical models, with emphasis on the measurements at forward rapidity using the Muon Spectrometer.

Speaker: Lizardo Valencia Palomo (Universite de Paris-Sud 11 (FR))

Slides LizardoValenciaPalomoSQM.pdf

122 Upsilon Production in Pb-Pb and p-Pb Collisions at Forward Rapidity with ALICE at the LHC

The ALICE apparatus at the LHC was designed and built to perform dedicated studies of the Quark-Gluon Plasma (QGP), a strongly interacting QCD matter deconfined state, expected to be created in high energy heavy-ion collisions. In such collisions heavy flavours are produced at the very early stage of the interaction in the initial hard scattering processes and hence can be used to characterize the hot and dense medium. In particular the bottonium family was proposed as a thermometer of the deconfined medium. In ALICE, the Upsilon(1S) meson can be measured in its dimuon decay channel at forward rapidity (2.5 < y < 4.0). In this talk, results on the Upsilon(1S) nuclear modification factor (RAA) in Pb-Pb collisions at a Nucleon-Nucleon c.m. energy of 2.76 TeV will be discussed and will be compared to the measurement at midrapidity by CMS and to theoretical predictions.

Speaker: Palash Khan (Saha Institute of Nuclear Physics (IN))

Slides 20130726PalashKhanUpsilonSQM.pdf

123 Open Heavy Flavor Production in Heavy-ion Collisions from STAR

(for the STAR Collaboration) Recent RHIC measurements support that a strongly coupled nuclear matter with parton degree of freedom has been created in relativistic heavy-ion collisions. However, the thermalization of such a hot and dense medium is still unclear. Heavy quarks are expected to be created from initial hard scatterings. Their large masses are not easily affected by the strong interaction with QCD medium, they thus carry clean information from the system at early stage. The interaction between heavy quarks and the medium is sensitive to the medium dynamics, especially sensitive to the degree of the system thermalization. Therefore heavy quarks are suggested as ideal probes to quantify the properties of the strongly interacting QCD matter. In this talk, we will present the STAR measurements of open charm hadron and its semileptonic decay electron (NPE) production in Au$+$Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. The centrality dependence of D-meson and NPE $p_T$ spectra, nuclear modification factors will be presented. The elliptic flow of $D^0$ and NPE will also be shown. The comparison between D-meson and NPE, and the status of separating bottom and charm contributions in NPE analysis, will be discussed.

Speaker: Prof. Yifei Zhang (University of Science and Technology of China)

Slides OpenHF_SQM2013_YF.pdf

Thermal models

124 Thermalization through Hagedorn-States

We examine the evolution of a heavy ion collision starting from non-equilibrium to an equilibrium state by looking at the corresponding thermalization times. Therefore we use the hadronic transport model "UrQMD" as microscopic model for high-energetic heavy ion collisions. Unfortunately these times are too long at present because detailed balance is not realized for all collisions which may occur. This especially holds for strange mesons like Kaons and hypreons like Lmabda, Sigma. etc.. In order to get rid of this drawback we deploy non-strange and strangeness-carrying Hagedorn-States proposed by the "Statistical Bootstrap Model". We study the question, whether creation of these states in binary collisions and their decay into two particles only will lower the thermalization times in UrQMD.

Speaker: Mr Maxim Beitel (Institut für Theoretische Physik, Goethe Universität)

Slides beitel.pdf

125 Dynamical freeze-out criterion in event-by-event hydrodynamics

In hydrodynamical modeling of the ultrarelativistic heavy-ion collisions the freeze-out is typically performed at a constant temperature. In this work we introduce a dynamical freeze-out criterion, which compares the hydrodynamical expansion rate with the pion scattering rate [1]. Previous studies [2] have shown that differences between constant temperature and dynamical freeze-out criteria are small in the transverse momentum spectra, but the effect on flow anisotropies has not yet been studied. Recently many calculations have been done using event-by-event hydrodynamics, in which case the expansion rate does not necessarily behave as nicely as in the case of smooth initial conditions. Thus it is interesting to check how the dynamical freeze-out changes hadron distributions with respect to the constant temperature freeze-out. In this contribution we present hadron spectra and elliptic and triangular flow calculated using (2+1)-dimensional ideal hydrodynamics, and show the differences between constant temperature and dynamical freeze-out criteria. First we discuss the systematics of the dynamical freeze-out, and for simplicity these calculations have been performed using smooth initial states. Finally dynamical freeze-out condition is applied to event-by-event calculations to evaluate v_2 and v_3. We find that in event-by-event calculations, pion v_2 is sensitive to the freeze-out criterion. [1] C. M. Hung and E. V. Shuryak, Phys. Rev. C 57, 1891 (1998). [2] K. J. Eskola, H. Niemi and P. V. Ruuskanen, Phys. Rev. C 77, 044907 (2008).

Speaker: Dr Pasi Huovinen (Frankfurt Institute for Advanced Studies)

Slides Huovinen_SQM13.pdf

126 Hadronic effects on the hadron abundances in heavy ion collisions

We present results from our recent investigation on the evolution of hadron abundances in heavy ion collisions. We study the production yields of hadrons with strangeness or charm quarks at the chemical freeze-out and their evolutions in the hadronic matter. The scattering cross sections with pions and rho mesons are studied in an effective Lagrangians to describe the dominant hadronic interaction during the hadronic stage of heavy ion collisions. We show that some hadron abundances may vary significantly and this result in return can tell us the lifetime of the hadronic phase in heavy ion collisions.

Speaker: Sungtae Cho

Slides 3.pdf

Plenary 11

Saturday, 27 July

Closing 1

Convener: Orlando Villalobos Baillie (University of Birmingham (GB))

127 eA

Speaker: Javier Lopez Albacete (IPhT-CEA)

Slides AlbaceteSQM2013.pdf

128 Theory summary: Quarks, Flow and Temperature in Spectra

Speaker: Tamas Biro (KFKI RMKI)

Paper SQMTheoSum.pdf

Slides SQM2013_Biro_TheoSum.pdf

10:10 Break

Closing 2

Convener: David Evans (University of Birmingham (GB))

129 SQM2013: Experimental Summary

Speaker: Andrea Dainese (Universita e INFN (IT))

Slides DaineseSQM2013.pdf

130 Next SQM

Slides Sorin_SQM_2015_JINR_Dubna.pdf Sorin_SQM_2015_JINR_Dubna.ppt

131 Closure

Speaker: Orlando Villalobos Baillie (University of Birmingham (GB))

Slides SQM2013-Closure.pdf SQM2013-Closure.pptx