11-th Polish Workshop on Relativistic Heavy-Ion Collisions

17 Jan 2015, 08:00 → 18 Jan 2015, 18:00 Europe/Zurich

107 (Building of the Faculty of Mathematics and Information Science, Warsaw University of Technology)

11-th Polish Workshop on Relativistic Heavy-Ion Collisions

17-18 January 2015

organized by

Heavy Ion Reactions Group, Faculty of Physics, 
Warsaw University of Technology

The Workshop will be focused on correlation and fluctuation measures used to characterize heavy-ion collisions at ultrarelativistic energies. Recent theoretical and experimental results from SPS, RHIC and the LHC will be covered.

Saturday, 17 January

09:30 → 10:00 Registration

10:00 → 12:35 Recent news from LHC

Convener: Wojciech Broniowski (IFJ PAN)

10:00 Welcome by the Vice-Rector of WUT prof. Rajmund Bacewicz and the Dean of Faculty of Physics prof. Miroslaw Karpierz

10:05 Finite Size of Hadrons and 3-Body Bose-Einstein Correlations

TBA

Speaker: Andrzej Bialas (Jagellonian U., Cracow, Poland)

Slides Bialas_warszawa2015a.pdf

10:30 fluctuations at the LHC and QCD phase diaggram

We will discuss how to construct fluctuations at the LHC and their relation to QCD phase boundary

Speaker: Prof. Krzysztof Redlich (Uni wroclaw)

Slides Redlich_HIC_Warszawa.pdf

10:55 Coffe break

11:20 ALICE overview

TBA

Speaker: Jacek Tomasz Otwinowski (GSI - Helmholtzzentrum fur Schwerionenforschung GmbH (DE))

Slides Otwinowski_HI_PolishWorkshp_2015_Jacek.pdf

11:45 CMS results

TBA

Speaker: Bozena Boimska (National Centre for Nuclear Research (PL))

Slides Boimska_Workshop2015.pdf

12:10 The overview of the ATLAS experiment results on azimuthal anisotropy in high energy nuclear collisions

The results from the detailed measurements of the azimuthal anisotropy of charged particles in lead-lead collisions at $\sqrt{s_{NN}} = $ 2.76 TeV and proton-lead collisions at $\sqrt{s_{NN}} = $ 5.02 TeV are presented. Various experimental methods were used to analyze high statistics data set collected by ATLAS experiment. Multi-particle cumulants provide a measurement of $v_{n}$ harmonics free from contributions not related to the initial geometry and give an estimate of event-by-event fluctuations of the flow harmonics. In lead-lead collisions second Fourier harmonic, $v_{2}$, was measured with two-, four-, six- and eight-particle correlation while $v_{3}$ and $v_{4}$ were extracted with four-particle cumulants. The distributions of event-by-event harmonic flow coefficients $v_{n}$ for n=2-4 were also measured in lead-lead collisions. Both approaches provides independent estimate of the event-by-event fluctuations of the flow harmonics and agrees well. Finally the collective behaviour of charged particles produced in the proton-lead collisions was studied by the measurements of $v_{n}$ harmonics associated with the azimuthal modulation of two-particle correlation structures and also extracted with four-particle cumulant method. These measurements give insight into the nature of fluctuations in the initial geometry and the role of hydrodynamic response to the fluctuations.

Speaker: Dominik Karol Derendarz (Polish Academy of Sciences (PL))

Slides derendarz_Atlas_flow.pdf

12:35 → 14:00 Lunch break

14:00 → 19:00 Properties of nuclear matter

Convener: Marek Gazdzicki (Johann-Wolfgang-Goethe Univ. (DE))

14:00 Event-by-Event Fluctuations in High-Energy Reactions

The talk presents some new theoretical results on event-by-event fluctuations in high energy proton-proton and nucleus-nucleus collisions. Three subjects will be discussed: 1) the role of global conservation laws and applications of different statistical ensembles; 2) the strongly intensive measures of fluctuations; 3) fluctuations with incomplete particle identifications.

Speaker: Mark Gorenstein (Bogolyubov Institute for Theoretical Physics)

Slides gorenstein-1.pdf

14:25 Fluctuations and correlations from the energy scan in p+p and Be+Be interactions at the SPS energies

The NA61/SHINE experiment aims to discover the critical point of strongly interacting matter and study the properties of the onset of deconfinement. These goals are to be achieved by performing a two-dimensional phase diagram (T-mu_B) scan by measurements of hadron production properties in proton-proton, proton-nucleus and nucleus-nucleus interactions as a function of collision energy and system size. Close to the critical point an increase of fluctuations is predicted. In this contribution preliminary results on fluctuations and two-particle correlations in pseudorapidity and azimuthal angle will be presented for p+p and Be+Be interactions at SPS energies. The NA61 results will be compared with the corresponding data of other experiments and model predictions.

Speaker: Maja Katarzyna Mackowiak-Pawlowska (Warsaw University of Technology)

Slides pwhir.pdf

14:50 Chiral thermodynamics with charm

Chiral thermodynamics of charmed mesons is formulated at finite temperature within a $2+1+1$-flavored effective Lagrangian incorporating heavy quark symmetry. The charmed-meson mean fields act as an extra source which breaks the chiral symmetry explicitly. This leads to effective interactions of the light and heavy-light mesons, which depend on temperature. Effective masses of the scalar and pseudoscalar charmed-mesons tend to approach each other as increasing temperature, so that the splitting between the chiral partners is reduced. These chiral splittings turn out to be less sensitive to the light-quark flavors, attributed to the underlying heavy quark symmetry. Consequently, chiral symmetry restoration is more accelerated in the strange charmed-mesons than in the strange light mesons, and this is in striking contrast to the chiral SU(4) result.

Speaker: Dr Chihiro Sasaki (Frankfurt Institute for Advanced Studies)

Slides warsaw.pdf

15:15 Quantum flavor kinetics and chemical freeze-out

We present current status of a quantum kinetic formulation of the chemical equilibration process in dense hadronic matter at the hadronization transition. Delocalization of hadron wave functions at the Mott-Anderson transition (where their binding energies vanish) lead to a divergence of scattering lengths and critical enhancement of rearrangement collisions between hadrons. We exemplify this for different meson-meson scattering processes from light (pi-pi scattering) to heavy flavors (charmonium dissociation). On this basis we suggest that chemical freeze-out has to be correlated with (partial) chiral symmetry restoration.

Speaker: David Blaschke (University of Wroclaw)

Slides Blaschke_PHIC_2014-15.pdf

15:40 Comparative studies of pion spectra in p+p and Pb+Pb collisions

In this talk I shall address the characteristic structures in the ratio of negative pion spectra in Pb+Pb divided by p+p collisions, published by NA61/SHINE and presented by Antoni Aduszkiewicz in the previous Workshop in this series. I will try to shed some light on these structures on the basis of information obtained from peripheral Pb+Pb reactions at top SPS energy. In the latter reactions, charatceristic structures present when comparing to p+p appear as a conglomerate of hadronic, isospin and electromagnetic effects.

Speaker: Andrzej Rybicki (Polish Academy of Sciences (PL))

Slides Rybicki_xipwohic.pdf

16:05 Coffe break

16:30 High-energy parton in unstable QGP

The momentum distribution of quark-gluon plasma at the early stage of relativistic heavy-ion collisions is anisotropic and consequently, the system is unstable due chromomagnetic plasma modes. We consider a high-energy parton, which flies across such an unstable plasma, showing that the parton either loses or gains an energy in dependence of initial conditions. The energy transfer is studied as an initial value problem. We have checked that in the limit of equilibrium plasma the highly-energetic parton loses the energy and the well-known formula of the collisional energy-loss is reproduced. Consequences of our findings for a phenomenology of jet quenching in relativistic heavy-ion collisions are discussed.

Speaker: Stanislaw Mrowczynski (Jan Kochanowski University)

Slides Mrowczynski.pdf

16:55 Status of the NICA heavy-ion project at JINR

The main physics goal of the NICA project at JINR (Dubna) is experimental study of the fundamental properties of the QCD matter by the relativistic heavy-ion collisions. The new accelerator complex NICA will provide a broad range of ion beams (from protons to gold nuclei) at energies from 1 to 4.5 GeV per nucleon. The data taking will start in 2017 at the fixed-target BM@N experiment at the Nuclotron with a further extension of the exploration range to CM energies of 4-11 GeV after putting the NICA collider into operation. Multi-Purpose Detector (MPD) at NICA is a versatile device designed for the study of multiple fascinating dynamical phenomena in heavy-ion collisions including event-by-even fluctuations and correlations. In my report I will discuss the main objectives of the NICA physics program and overview the current status of the project realization

Speaker: Vladimir Kolesnikov (Joint Institute for Nuclear Research (JINR))

Slides Kolesnikov_Warsaw.pdf

17:20 Inhomogeneous condensation in dense nuclear matter

We investigate the emergence of inhomogeneous condensation at nonzero density in effective models of QCD. In particular, we present results for the chiral density-wave solution in nuclear matter in the so-called extended linear sigma model, which is an effective hadronic model. Then we test more general forms of inhomogeneous condensation in QCD-ispired models models in 1+1 dimensions (Gross-Neveu model and variants of it) and in 1+3 dimensions (Nambu Jona-Lasinio model).

Speaker: Francesco Giacosa (JW Goethe University)

Slides GiacosaWarsaw.pdf

17:45 Possible Implication of a Single Nonextensive pT Distribution for Hadron Production in High-Energy pp Collisions

Multiparticle production processes in pp collisions at the central rapidity region are usually considered to be divided into independent "soft" and "hard" components. The first is described by exponential (thermal-like) transverse momentum spectra in the low-pT region with a scale parameter T associated with the temperature of the hadronizing system. The second is governed by a power-like distributions of transverse momenta with power index n at high-pT associated with the hard scattering between partons. We show that the hard-scattering integral can be approximated as a nonextensive distribution of a quasi-power-law containing a scale parameter T and a power index n = 1/(q−1), where q is the nonextensivity parameter. We demonstrate that the whole region of transverse momenta presently measurable at LHC experiments at central rapidity (in which the observed cross sections varies by 14 orders of magnitude down to the low pT region) can be adequately described by a single nonextensive distribution. These results suggest the dominance of the hard-scattering hadron-production process and the approximate validity of a “no-hair" statistical-mechanical description of the pT spectra for the whole pT region at central rapidity for pp collisions at high-energies.

Speaker: Grzegorz Andrzej Wilk (National Centre for Nuclear Research (PL))

Slides HIP2015_Wilk.pdf HIP2015_Wilk.pptx

18:10 Correlations and Fluctuations at Warsaw University of Technology

Speaker: Jan Marian Pluta (Warsaw University of Technology (PL))

Slides

• Grebieszkow_17_01_2015_NA61group_from_WUT_short.pdf
• HYDRO.Slodkowski.2015.01.17.pdf
• STAR_PLATFORMA_(1).pdf
• WFGroup-ALICE-ZPCJ.pdf

19:30 → 22:00 Conference dinner

Sunday, 18 January

09:00 → 14:00 Models for heavy-ion collisions

Convener: Stanislaw Mrowczynski (Jan Kochanowski University)

09:00 Collective flow in He-Au collisions

TBA

Speaker: Piotr Bozek

Slides Bozek_bozekwaw.pdf

09:25 $\alpha$ clusters in ultra-relativistic light-ion + Pb collisions at CERN SPS

We investigate ultra-relativistic collisions of the light nuclei with heavy targets at energies available at CERN SPS and show that the harmonic flow measures based on ratios of cumulant moments are particularly suited to study the intrinsic deformation of the light nuclei wave functions. That way one can probe the expected clusterization in the ground state, which leads to large initial ellipticity or triangularity in the shape of the fireball in the transverse plane. We show that the clusterization effect results in very characteristic behavior of the ratios of the cumulant moments as functions of the number of participant nucleons, both for the elliptic and triangular deformations. Thus the experimental event-by-event studies of harmonic flow in ultrarelativistic light-heavy collisions may offer a new window to look at the ground-state structure of light nuclei.

Speaker: Maciej Rybczynski (Jan Kochanowski University (PL))

Slides Rybczynski_XI_Polish_Workshop_v5.pdf

09:50 Ultrarelativistic proton-beryllium collisions

We investigate ultrarelativistic p-9Be and p-7Be collisions. It is shown that the clustered structure of beryllium leads to large (order of magnitude, thus possibly observable) effects in the distribution of the participant nucleons in the case when berillium is polarized. In general, our method can be used to probe the structure of light nuclei whose ground state spin is nonzero.

Speaker: Wojciech Broniowski (IFJ PAN)

Slides Broniowski_Polish11_v2.pdf

10:15 Strong correlations in the QGP at realistic coupling

Experimental results from relativistic heavy-ion collisions at RHIC and LHC have shed light on the strongly coupled nature of the quark-gluon plasma (QGP) in the experimentally available range of temperatures. These features are not within the reach of conventional perturbative methods, such as the Hard-Thermal-Loop (HTL) effective theory, and are deeply related to the lack of infrared stability of the (chromo)magnetic gluons. We present a novel approach which explicitly incorporates effects of color confinement leading to the appereance of a (chromo)magnetic scale at finite temperatures. Firstly, we investigate the collective excitations of hot QCD in order to get a handle of the relevant d.o.f. in a QGP. In stark contrast to conventional HTL expectations, we find three collective modes or quasi-particles (instead of two as from conventional HTL) as well as a modified analytical structure of the relevant propagators. The novel mode is massless and implies positivity violation of the spectral function. Secondly, we also estimate the heavy-quark potential incorporating effects from the (chromo)magnetic scale in order to study the string-breaking mechanism at finite temperatures and their effects on the jet quenching parameter qhat.

Speaker: Konrad Tywoniuk

Slides Tywoniuk_11PolishWorkshop2015.pdf

10:40 Statistics of thermalization in Bjorken flow

Using the AdS/CFT correspondence we study non-equilibrium dynamics and the approach to the hydrodynamic region of N=4 supersymmetric Yang-Mills theory at strong coupling. We numerically evolve over 600 randomly generated far-from equilibrium initial conditions, characterized by an initial entropy. Based on this fairly large sample we confirm previous observations of early thermalization in N=4 SYM at strong coupling. I will present our results concerning thermalization times and entropy production, as well as various correlations. A particulary interesting example is the square-root correlation of the hydrodynamization temperature and the entropy at hydrodynamization.

Speaker: Jakub Jankowski (Jagiellonian University)

Slides Jankowski_Warszawa2015_v2.pdf

11:05 Coffe break

11:30 Centrality dependence of high energy jets in p+Pb collisions at the LHC

The recently measured centrality dependence of high energy jets in proton-lead collisions at the LHC is investigated. We conjecture that events with jets of very high energy (a few hundred GeV) are characterized by a suppressed number of soft particles thus shifting these events into more peripheral bins. This naturally results in the suppression (enhancement) of the nuclear modification factor, $R_{pA}$, in central (peripheral) collisions. Our calculations suggest that a moderate suppression of the order of $20\%$ can quantitatively reproduce the experimental data. We further propose an independent experimental test to verify this mechanism.

Speaker: Adam Bzdak (AGH University of Science and Technology)

Slides abzdak.pdf

11:55 Single particle spectra from the energy scan of p+p and Be+Be interactions in the SPS energy range

The NA61/SHINE experiment studies the onset of deconfinement in strongly interacting matter by performing a two-dimensional scan of particle production in beam momentum (13A, 20A, 30A, 40A, 75A and 150A GeV/c) and system size (p+p, 7Be+9Be, Ar+Sc, Xe+La, Pb+Pb). In this contribution, single particle spectra of pions, kaons and protons produced in inelastic p+p collisions and spectra of negatively charged pions produced in centrality selected Be+Be reactions will be presented. The energy dependence of observables sensitive to deconfinement and inspired by the Statistical Model of the Early Stage (kink, horn and step) already show interesting behaviour in p+p collisions, which is not described by the Monte-Carlo models. The Be+Be data indicate presence of collective effects. Influence of isospin effects will also be discussed based on the comparison between p+p and Be+Be data.

Speaker: Emil Aleksander Kaptur (University of Silesia (PL))

Slides Kaptur.pdf

12:20 Kinetic coefficients in non-conformal viscous hydrodynamics

Based on the exact solution of Boltzmann kinetic equation in the relaxation-time approximation, the precision of the two most recent formulations of relativistic second-order non-conformal viscous hydrodynamics (14-moment approximation and causal Chapman-Enskog method), standard Israel-Stewart theory, and anisotropic hydrodynamics framework, in the simple case of one-dimensional Bjorken expansion, is tested. It is demonstrated that the failure of Israel-Stewart theory in reproducing exact solutions of the Boltzmann kinetic equation occurs due to neglecting and/or choosing wrong forms of some of the second-order transport coefficients. In particular, the importance of shear–bulk couplings in the evolution equations for dissipative quantities is shown. One finds that, in the case of the bulk viscous pressure correction, such coupling terms are as important as the corresponding first-order Navier-Stokes term and must be included in order to obtain, at least qualitative, overall agreement with the kinetic theory. Literature: G.S.Denicol, W.Florkowski, R.Ryblewski, M.Strickland, Phys.Rev. C90 (2014) 044905 A.Jaiswal, R.Ryblewski, M.Strickland, Phys.Rev. C90 (2014) 044908

Speaker: Dr Radoslaw Ryblewski (Institute of Nuclear Physics PAS)

Slides ryblewski.pdf

12:45 New formulation of leading-order anisotropic hydrodynamics

New formulation of leading-order anisotropic hydrodynamics ---------------------------------------------------------- In ultrarelativistic heavy-ion collisions nuclear matter is heated to a temperature exceeding that necessary to create a quark-gluon plasma (QGP). Traditionally, second order viscous hydrodynamics has been used to reproduce the soft collective flow of the QGP and hadronic spectra; however, due to rapid longitudinal expansion in the early stages of evolution, the system may possess substantial pressure anisotropies which are a consequence of large viscous corrections.  These large corrections may lead to unphysical results.  In order to more accurately treat systems possessing large pressure anisotropies, a new approach called anisotropic hydrodynamics was recently developed.  In this approach, the pressure anisotropy is treated non-perturbatively at leading order in the hydrodynamic expansion.  This allows one to match with second order viscous hydrodynamics in the close to equilibrium limit and to also have a striking agreement with the exact solution for large anisotropies.  We are presenting the latest formulation of the leading-order for anisotropic hydrodynamics, which uses a general ellipsoidal ansatz for the underlying distribution function, and dynamical equations resulting from the moments of the Boltzmann equation. Differently from previous approaches, we don't require any symmetry for the flow, like longitudinal boost invariance or cylindrically symmetric radial flow. References [1] L. Tinti, (3+1)-dimensional framework for leading-order non conformal anisotropic hydrodynamics, arXiv:1411.7268.

Speaker: Leonardo Tinti (Jan Kochanowski University)

Slides Tinti_11PWoHIC.pdf

13:10 Onset of Pion Condensation at the LHC

We show that the recent LHC data on transverse-momentum spectra of hadrons produced in PbPb collisions at sqrt(sNN) = 2.76 TeV can be explained by the hadronization out of equilibrium [1,2]. The values of our fit parameters suggest the onset of pion Bose condensation. We determine the number of pions in the condensate and make predictions for the pion spectra at low p_T [3]. We further argue that the Bose condensation has even stronger impact on the fluctuations and correlations of pions [4,5], and present some quantitative estimates of expected effects. [1] V. Begun, W. Florkowski and M. Rybczynski, Phys. Rev. C 90 (2014) 5, 054912 [arXiv:1405.7252 [hep-ph]]. [2] V. Begun, W. Florkowski and M. Rybczynski, Phys. Rev. C 90 (2014) 1, 014906 [arXiv:1312.1487 [nucl-th]]. [3] V. Begun, W. Florkowski, work in progress. [4] V. V. Begun and M. I. Gorenstein, Phys. Rev. C 77 (2008) 064903 [arXiv:0802.3349 [hep-ph]]. [5] V. V. Begun and M. I. Gorenstein, Phys. Lett. B 653 (2007) 190 [hep-ph/0611043].

Speaker: Dr Viktor Begun (UJK)

Slides Begun_Onset.pdf