XI Workshop on Particle Correlations and Femtoscopy

3 Nov 2015, 08:00 → 7 Nov 2015, 18:25 Europe/Zurich

Main Auditorium (Centre for Innovation and Technology Transfer Management, Warsaw University of Technology)

XI Workshop on Particle Correlations and Femtoscopy

3-7 November 2015

Warsaw, Poland

organized by

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

       

 

Scientific information and topics
This event follows the tradition of previous editions by bringing together experts and other interested researchers in the field of particle-particle correlations and “femtoscopy” in nuclear and particle physics. The topics covered by the WPCF workshop concern dynamical and thermo-dynamical properties of emitting sources produced in heavy-ion collisions, including links to phase transitions and equation of state properties. Moreover, two- and multi-particle correlation measurements provide tools to reveal the existence of new resonances (both at high and at low energies) and phenomena such as nuclear clusters and molecules and spectroscopic properties of unbound states.
The scope of the meeting will include correlation and femtoscopy research at RHIC/LHC energies and at low and intermediate energies as well.
Topics:

• Femtoscopy at RHIC and LHC: links to QGP physics
• Femtoscopy in A+A, p+p , p+A and e⁺-e^- collisions at relativistic energies
• Femtoscopy at intermediate energies: links to the EoS of asymmetry nuclear matter
• Charge fluctuations and correlations
• Fluctuation in initial conditions
• Collective flow and correlations
• Resonance decays at RHIC and LHC
• Resonance decay spectroscopy in low and intermediate energy reactions
• Correlations, cluster states, nuclear molecules and production of boson condensates in nuclei
• New methods and facilities

These topics will be covered with invited and contributed talks, selected from received abstracts. Participation and abstract submission by students and postdocs are strongly encouraged. More details on the program will be provided on the second circular and on the conference web site, http://indico.cern.ch/e/wpcf2015.

WPCF 2015 is associated with "NICA-days 2015", that will be held at the same place and time. Common sessions are envisaged as well, expecting interests of participants in the topics of both conferences. See the web page of NICA-days 2015: http://indico.cern.ch/e/nica2015.

Disclaimer:
The banner picture on top of this page is adapted from https://commons.wikimedia.org/wiki/File:Panorama_Warszawy_by_Night_SS.jpg.
The background picture in the poster is adapted from https://commons.wikimedia.org/wiki/File:Palace_of_Culture_and_Science_nightshot.JPG.
These files are licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.

 

AnnouncementThursdayEvents.pdf

KalliopiPetrou_programme.pdf

Presentation_Dinner.pdf

Szubstarska_Kupczynski_Programme.pdf

WPCF2015_Final_Announcement.pdf

WPCF_2015_poster.pdf

Tuesday 3 November

Registration

Opening session

Convener: Adam Kisiel (Warsaw University of Technology (PL))

1 Welcome

Speaker: Rajmund Bacewicz (Warsaw University of Technology)

2 Welcome

Speaker: Anita Uchanska (Warsaw University of Technology)

CZIiTT_litopad_2015_funkcje_eng.pdf

CZIiTT_litopad_2015_funkcje_eng.ppt

3 Welcome

Speaker: Richard Lednicky (Joint Institute for Nuclear Research, Dubna, Russia)

4 Welcome

Speaker: Michael Waligorski (National Atomic Energy Agency)

5 Brief history of femtoscopy and WPCF - personal view

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

JP-WPCF15.pdf

JP-WPCF15.ppt

10:20 Coffee break

Session 2

Convener: Richard Lednicky (Joint Institute for Nuclear Research, Dubna, Russia)

6 NICA project

Speaker: Vladimir Kekelidze (Joint Inst. for Nuclear Research (RU))

7 Femtoscopy: the way back in the energy scale from ALICE to NICA

Speakers: Daniel Wielanek (Warsaw University of Technology), Ludmila Malinina (Joint Inst. for Nuclear Research (RU))

femto_malinina_NICA_WPCF2015_2.pdf

Femtoscopic study at MPD facility 2.pdf

Femtoscopic study at MPD facility 2.pptx

8 From the Physical Model to the Electronic System - OMTF Trigger for CMS

Speaker: Wojciech Zabolotny (Warsaw University of Technology)

OMTF-from-model.pdf

9 Dense cold baryonic matter

Speaker: Alexey Stavinskiy (ITEP,Moscow)

Stavinskiy-NICA-DAYS-Warsaw-2015.pdf

12:50 Lunch

Session 3

Convener: Ludmila Malinina (Joint Inst. for Nuclear Research (RU))

10 Three decades of femtoscopy in relativistic heavy ion collisions: from the roots up (lecture for students)

Speaker: Mike Lisa (Ohio State University (US))

11 Results and Future of Beam Energy Scan (BES) Program at RHIC

Speaker: Grazyna Odyniec

WPCF_2015_WAW.pdf

15:35 Coffee break

Special session

Mrowczynski.pdf

Welcome reception

KalliopiPetrou_programme.pdf

Wednesday 4 November

Session 4

Convener: Tamas Csorgo (Hungarian Academy of Sciences (HU))

12 Correlation measurement of particle strong interaction

Basic assumptions behind the correlation measurement of particle strong interaction are reviewed and recent results are discussed.

Speaker: Richard Lednicky (JINR Dubna, RF)

lednicky_warsaw_wpcf_2015.pdf

13 Blast-wave model description of the Hanbury-Brown -Twiss radii in pp collisions at LHC energies

The blast wave model is applied to the recent data on HBT radii in pp collisions, measured by the ALICE collaboration. A reasonable description of data is obtained for a rather low temperature of the kinetic freeze-out, T = 100 MeV, and the transverse profile corresponding to the emission from a shell of a fairly small width of about 1.5 fm. The size and the life-time of the produced system are determined for various multiplicities of the produced particles.

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

wpcf wflorkowski.pdf

14 Finite size of hadrons and Bose-Einstein correlations

Speaker: Andrzej Bialas

Bialas.pdf

10:15 Coffee break

Session 5

Convener: Wojciech Broniowski (IFJ PAN)

15 Global hyperon polarization at RHIC

Speakers: Mike Lisa (Ohio State University (US)), Mike Lisa (Ohio State University (US))

LisaWPCF2015final.pdf

LisaWPCF2015final.pdf

LisaWPCF2015final.pptx

16 K0sKch femtoscopy in Pb-Pb collisions at sqrt(s)=2.76 TeV from the LHC ALICE experiment

Femtoscopic correlations with the particle pair combinations K$^0_{\rm S}$K$^{\rm \pm}$ are studied for the first time. This method has been applied to Pb-Pb collisions at $\sqrt{s_{\rm NN}}=2.76$ TeV by the LHC ALICE experiment. Correlations in the K$^0_{\rm S}$K$^{\rm \pm}$ pairs are produced by final-state interactions which proceed through the a$_{\rm 0}$(980) resonance. It is found that the a$_{\rm 0}$ final-state interaction describes the shape of the measured K$^0_{\rm S}$K$^{\rm \pm}$ correlation functions well. The extracted radius parameter for K$^0_{\rm S}$K$^{\rm -}$ is found to be equal to that for K$^0_{\rm S}$K$^{\rm +}$ within the errors of the present measurement. Comparing the results of the present study with those from identical-kaon femtoscopic studies by ALICE, mass and coupling parameters for the a$_{\rm 0}$ resonance are constrained and the branching ratio of non-resonance to resonance final-state interactions for K$^0_{\rm S}$K$^{\rm \pm}$ is estimated.

Speaker: Thomas Humanic (Ohio State University (US))

2015-Oct-30-conferencefile-humanic_WPCF15v4.pdf

17 On mT dependence of femtoscopy scales for meson and baryon pairs

Speaker: Yuriy Sinyukov (Bogolyubov Institute for Theoretical Physics)

Sinyukov-WPCF-2015.pdf

18 Pomeron Femtoscopy

Speaker: Tamas Csorgo (Hungarian Academy of Sciences (HU))

2015-11-04-Csorgo-Pomeron-Femtoscopy-WPCF-2015.pdf

2015-11-04-Csorgo-Pomeron-Femtoscopy-WPCF-2015.pdf

2015-11-04-Csorgo-Pomeron-Femtoscopy-WPCF-2015.pptx

12:25 Lunch

Session 6

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

19 NA61/SHINE results on fluctuations and correlations at CERN SPS energies

The aim of the NA61/SHINE strong interaction programme is to explore the phase diagram of strongly interacting matter. The main physics goals are the study of the onset of deconfinement and the search for the critical point of strongly interacting matter. These goals are pursued by performing an beam momentum (13A - 158A GeV/c) and system size (p+p, p+Pb, Be+Be, Ar+Sc, Xe+La) scan. This contribution presents results on transverse momentum, charge and multiplicity fluctuations from the Be+Be and p+p energy scan. Also, results on two-particle correlations in pseudorapidity and azimuthal angle obtained in p+p interactions will be shown. The influence of conservation laws and resonance decays on multiplicity and chemical fluctuations of identified particles in p+p interactions will be discussed. Obtained results will be compared with Pb+Pb collisions and with model predictions.

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

wpcf2015_mmp.pdf

20 Event-by-event dynamical fluctuations of K/π, p/π, and K/p in Pb-Pb collisions with ALICE

The study of event-by-event fluctuations of identified hadrons may reveal the degrees of freedom of the strongly interacting matter created in heavy-ion collisions and reflect the underlying dynamics of the system. The observable νdyn, which is given in terms of the moments of identified-particle multiplicity distributions, is used to quantify the magnitude of the dynamical fluctuations in event-by- event measurements of given particle ratios. The ALICE detector at the LHC is well suited for the study of νdyn, due to its excellent particle identification capabilities. Particle identification that is based on the measurement of the specific ionization energy loss dE/dx works well on a statistical basis, however, suffers from ambiguities when applied on the event-by- event level. A novel experimental technique called the "Identity Method" was recently proposed to overcome such limitations. The method follows a probabilistic approach using the inclusive dE/dx distributions measured in the ALICE TPC, and determines the moments of the multiplicity distributions by an unfolding procedure. In this contribution, we will present dynamical K/π, p/π, and K/p fluctuation analysis, which applies the Identity Method to Pb-Pb data from ALICE. We will also show comparisons to some theoretical models and the lower energy measurements at CERN-SPS and RHIC.

Speaker: Mr Mesut Arslandok (Goethe University, Frankfurt)

WPCF15_MesutArslandok.pdf

21 Correlations and fluctuations of pions at the LHC

The intriguing possibility of Bose-Einstein condensation of pions (BEC) at the LHC [1-3] is examined with the use of higher order moments of the multiplicity distribution. The scaled variance, skewness and kurtosis are calculated for the pion system in and out of chemical equilibrium. The effects of resonance decays are estimated. The obtained results show the possibility to see a significant increase of the kurtosis for the case of BEC in the measured data. [1] Bose-Einstein condensation of pions in heavy-ion collisions at the CERN Large Hadron Collider (LHC) energies By Viktor Begun, Wojciech Florkowski. arXiv:1503.04040 [nucl-th]. Phys.Rev. C91 (2015) 054909. [2] Transverse-momentum spectra of strange particles produced in Pb+Pb collisions at sNN‾‾‾‾√=2.76 TeV in the chemical non-equilibrium model By Viktor Begun, Wojciech Florkowski, Maciej Rybczynski. arXiv:1405.7252 [hep-ph]. Phys.Rev. C90 (2014) 5, 054912. [3] Explanation of hadron transverse-momentum spectra in heavy-ion collisions at s√NN= 2.76 TeV within chemical non-equilibrium statistical hadronization model By Viktor Begun, Wojciech Florkowski, Maciej Rybczynski. arXiv:1312.1487 [nucl-th]. Phys.Rev. C90 (2014) 1, 014906.

Speaker: Viktor Begun

Begun_HMoments_LHC.pdf

22 Hadron production within PHSD

We study the production of (anti-) strange and multi-strange hadrons in heavy-ion collisions from FAIR/NICA to LHC energies within the Parton-Hadron-String Dynamics (PHSD) microscopic transport approach, which contains the partonic and hadronic dynamics. By showing the channel decomposition for the strangeness production we demonstrate how with increasing energy the production in the QGP dominates the hadronic production. We observed traces from the QGP by looking at a verity of ‘bulk’ observables like the excitation functions of particle yields, pt- and rapidity distributions, centrality dependencies of yields, etc. A striking disagreement between the PHSD results and the available data persists for bombarding energies below $\sqrt{s_{NN}} \approx$ 8 GeV where the strangeness production is significantly underestimated as in earlier HSD studies. This finding implies that the strangeness enhancement seen experimentally at FAIR/NICA energies cannot be attributed to a deconfinement phase transition or crossover but probably involves the approximate restoration of chiral symmetry in the hadronic phase.

Speaker: Pierre Moreau (Frankfurt Institute of Advanced Studies)

P.Moreau_WPCF2015.pdf

15:40 Coffee Break

Session 7

Convener: Mike Lisa (Ohio State University (US))

23 Two-particle correlations in pp collisions at 13 TeV measured with CMS

Results on two-particle angular correlations for charged particles emitted in pp collisions at a center-of-mass energy of 13 TeV are presented. The correlations are studied as a function of charged-particle multiplicity and transverse momentum (pT). In high-multiplicity events, a long-range (|eta| > 2.0), near-side (Delta_phi =# 0) structure emerges in the two-particle Delta_eta - Delta_phi correlation functions. The overall correlation strength is similar to that found in earlier pp data at 7 TeV, but is measured up to much higher multiplicity values.

Speaker: Sunil Manohar Dogra (UNESP - Universidade Estadual Paulista (BR))

Dogra_SM_wpcf_2015.key

Dogra_SM_wpcf_2015.pdf

Dogra_SM_wpcf_2015.pptx

24 Measurement of the ridge and Bose-Einstein correlations in pp and pPb collisions with the ATLAS detector at the LHC

ATLAS measurement of azimuthal correlations between particle pairs at large pseudorapidity separation in pp and pPb collisions are presented. The data were collected using a combination of the minimum-bias and high track-multiplicity triggers. A detailed study of the dependence of two-particle correlations on the charged particle multiplicity, transverse momentum of the pair constituents and the pseudorapidity separation between particles forming a pair is shown. Measurements of multi-particle cumulants in the azimuthal angles of produced particles in wide pseudorapidity (|η|<2.5) and multiplicity ranges, with the aim to extract a single particle anisotropy coefficient, v1-v5, are also presented. These measurements can help to understand the origin of the long-range correlations seen in high-multiplicity pp and p+Pb collisions. In addition, one and three-dimensional HBT radii in p+Pb collisions are presented as a function of event centrality. An estimation of dE/dx in the pixel detector is used to identify charged pions. These particles are selected from |η| < 2.5 and the measurement is performed in several pair-average momentum (kT) bins from 0.1 GeV to 1.0 GeV. The measured source sizes are observed to increase with collision centrality. The contribution to the correlation function from hard processes is studied and a novel method for tuning the amplitude of this background in the data is introduced.

Speaker: Michael Felix Clark (Columbia University)

clark_hbt_slides.pdf

25 Charged kaon femtoscopy with ALICE at LHC

Femtoscopy allows for measurements of the space-time characteristics of particle production using correlations resulting from the effects of quantum statistics and final state interactions. We present the results of femtoscopic analyses for charged kaons measured by ALICE in Pb- Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV. Kaon femtoscopy is a substantial supplement to that of pions because it allows one to distinguish between different model scenarios working equally well for pions. Particularly, we compare the measured 3D kaon radii with a model where the hydrodynamic phase is followed by a hadronic rescattering phase and a purely hydrodynamical calculation. The latter predicts an approximate $m_{\mathrm{T}}$ scaling of source radii obtained from pion and kaon correlations. This $m_{\mathrm{T}}$ scaling appears broken in our data, which indicates strong rescattering in the hadronic phase at LHC energies. The decoupling time of the system is also estimated using the three-dimensional femtoscopic analysis for kaons, and compared with such estimates obtained from pions.

Speaker: Ludmila Malinina (JINR & SINP MSU)

femto_Malinina_ALICE_WPCF2015.pdf

26 Femtoscopy with unlike-sign kaons at STAR in 200 GeV Au+Au collisions

Experiments with high-energy heavy-ion collisions study properties of nuclear matter and its transition from hadrons to a state of deconfined quarks and gluons, the Quark-Gluon Plasma (QGP). Femtoscopic measurements of two-particle correlations at small relative momenta reveal the space-time characteristics of the system at the moment of particle emission. It has been predicted that correlations due to the strong final-state interactions (FSI) in a system with a narrow near-threshold resonance will be sensitive to the source size in the region of the resonance. Such a measurement can provide complementary information to the measurements at very low relative momenta. Since phi-meson ($\phi(1020)$) is a narrow resonance, it is ideal for the femtoscopic analysis of unlike-sign kaon pairs. In this talk, we will present a status report of a STAR analysis of unlike-sign kaon femtoscopic correlations in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV. The experimental results will be compared to theoretical predictions that include the treatment of resonance formation due to final-state interactions.

Speaker: Jindrich Lidrych (Czech Technical University in Prague)

wpcf_KK_lidrych.pdf

Thursday 5 November

Excursion

Session 8

27 Extraordinary Claims: the 0.000029% solution - Faculty Seminar combined with WPCF

Speaker: Tommaso Dorigo (Universita e INFN, Padova (IT))

13:00 Lunch

Special session: IAC meeting

Mrowczynski.pdf

Session 9

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

28 Superstatistical cluster decay

I shall provide an overview of Tsallis statistics, presented as a special case of superstatistics and applied to the multiparticle processes described by the statistical cluster model. This model combines Boltzman statistics applied to hadronization of clusters and superstatistics induced by fluctuations of their Lorentz factors. It results in a Tsallis-like distribution of transverse momenta with some scale, the origin of which is discussed. We show that this distribution becomes a Tsallis distribution in a special case, namely when one combines fluctuations of the Lorentz factor and temperature inside the cluster, given by beta and gamma distributions, respectively [1]. [1] G.Wilka and Z.Włodarczyk, Phys. Lett. A, in print; available online at http://dx.doi.org/10.1016/j.physleta.2015.08.038 and also as arXiv:1506.06074 [hep-ph].

Speaker: Prof. Grzegorz Wilk (NCNR)

XI-WPCF_GWilk.pdf

29 The q-Statistics and QCD Thermodynamics at RHIC and LHC: A Systematic Study of Particle Spectra

Tsallis non-extensive thermodynamics has been successfully used in describing the transverse momentum distributions from RHIC to LHC energies. In this work, we present a simplified and thermodynamically consistent Tsallis distribution by using Taylor series expansion in (q-1). It helps us to study the degree of deviation of Tsallis distribution from a thermalized Boltzmann distribution, for proton-proton collisions at LHC energies. We provide analytical results for the Tsallis distribution in the presence of collective flow up to the first order in (q-1) and observe that the pion $p_{T}$ spectrum for Pb+Pb collisions at center of mass energy of 2.76 TeV at LHC, could be well described by Tsallis q-statistics with inclusion of a constant radial flow. We study the degree of deviation of the thermodynamic observables like, the number density, pressure and energy density, from a Boltzmann type of distribution, in the ambient of Tsallis q-statistics, for different physically acceptable values of the q-parameter. Further, we extend the q-statistics for the Hagedorn resonance gas to examine the basic thermo-dynamical quantities for systems having different ‘q’ parameters. The speed of sound and thus the equation of state in a Hagedorn resonance gas is also studied in the framework of non-extensive statistics. We extend the studies for a comparison with a physical resonance gas.

Speaker: Raghunath Sahoo (Indian Institute of Technology Indore (IN))

wpcf-rns-Final.pdf

30 Can we obtain a "new femtoscopy" on the basis of electromagnetic effects?

In this talk we review our studies of spectator-induced electromagnetic (EM) effects on charged pion emission in ultrarelativistic heavy ion collisions. These effects are found to consist in the electromagnetic *charge splitting* of pion directed flow as well as very large distortions in spectra and ratios of produced charged particles. As it emerges from our analysis, they offer sensitivity to the actual distance $d_E$ between the pion formation zone at freeze-out and the spectator matter. As a result, this gives a new possibility of studying the space-time evolution of dense and hot matter created in the course of the collision. Having established that $d_E$ traces the longitudinal evolution of the system and therefore rapidly decreases as a function of pion rapidity, we investigate the latter finding in view of pion feed-over from intermediate resonance production. As a result we obtain a first estimate of the pion decoupling time from EM effects which we compare to existing HBT data. We conclude that spectator-induced EM interactions can serve as a new tool for studying the space-time characteristics and longitudinal evolution of the system. We discuss the future perspectives for this activity on the basis of existing and future data from NICA, NA61/SHINE, STAR and ALICE experiments.

Speaker: Andrzej Rybicki (H. Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences)

Rybicki_WPCF_2015.pdf

15:45 Break

Session 10

Convener: Thomas Humanic (High Energy Physics Group, Department of Physics)

31 Nonfemtoscopic correlations study with EPOS model

Correlations at small relative velosities are not limited by identical particle interferometry and FSI effects. Others contributions are visible experimentally and should be studied both as the source of systematic errors in femtoscopic measurements and as potential new source of information about the process. The study of such a correlations within EPOS model is presented. It was found that most prominent nonfemtoscopic effects related with nonuniformity of data sample rather then with kinematical or minijets effects.

Speaker: Dr Alexey Stavinskiy (ITEP,Moscow)

Stavinskiy-WPCF-2015-Nonfemto-29-10-15-f.pdf

32 Interferometry of rotating sources

It is shown that rotational of a cylindrically symmetric system can be perceived as asymmetric by the azimuthal HBT method. We study an exact rotating and expanding solution of the fluid dynamical model of heavy ion reactions, that take into account the rate of slowing down of the rotation due to the longitudinal and transverse expansion of the system. The parameters of the model are set on the basis of realistic 3+1D fluid dynamical calculation at TeV energies, where the rotation is enhanced by the build up of the Kelvin Helmholtz Instability in the flow.

Speaker: Sindre Velle (University of Bergen)

WPCF15-velle.pdf

33 Description of multipole asymmetries with Buda Lund hydrodynamical model

The Buda-Lund hydro model describes an expanding ellipsoidal fireball, and fits the observed elliptic flow and the second order HBT oscillations successfully. If the finite number of nucleons are taken into account then the shape of the fireball fluctuates on an event-by-event basis and specifies the final state asymmetries which can be translated into a series of multipole anisotropy coefficients. These anisotropies then result in measurable phase-space anisotropies, to be measured with respect to their respective symmetry planes. In my talk I present an updated, multipole version of the Buda-Lund model and investigate the resulting higher order flow coefficients and the oscillations of the HBT radii.

Speaker: Sándor Lökös

WPCF_15_Lokos.pdf

34 Baryonic femtoscopy in heavy-ion collisions

Speaker: Dominik Arominski (Warsaw University of Technology (PL))

DArominskiWPCF2015.pdf

35 Proton-proton and proton-lambda correlations in p+Nb reactions measured with HADES

Speaker: Oliver Werner Arnold (Technische Universitaet Muenchen (DE))

oarnold_WPCF2015.pdf

Concert "Great Music in the Small Hall"

Friday 6 November

Session 11

Convener: Piotr Bozek (AGH University of Science and Technology)

36 Universality of particle production and energy balance in hadronic and nuclear collisions

A study of the universality of multihadron production in nucleus-nucleus and $pp/\bar{p}p$ collisions is performed using the dependencies of the midrapidity pseudorapidity and transverse energy densities and of the mean multiplicity on the collision energy and on the number of nucleon participants, or centrality, in the energy range from a few GeV to a few TeV. The approach in which the multiparticle production is driven by the dissipating centrality-dependent effective energy of participants is introduced exploiting the earlier proposed consideration that combines the constituent quark picture with Landau hydrodynamics. Within this approach, the data on the energy dependence of the global variables studied and the pseudorapidity spectra from the most central nuclear collisions are well reproduced. The centrality dependence of the midrapidity pseudorapidity and transverse energy densities of charged particles are well described pointing to a similarity in the most central collisions and centrality data. The study of the mean multiplicty centrality dependence reveals a new scaling between the measured and calculated pseudorapidity spectra. Using this scaling, called the energy balanced limiting fragmentation scaling, one reproduces the pseudorapidity spectra at all centralities. The obtained scaling clarifies on the differences in the multiplicty centrality dependence from RHIC and LHC as well as on the this dependence of the midrapidity pseudorapidity density vs. multiplicity at RHIC. A complementarity in the multiplicity energy dependence in the most central collisions and centrality data is obtained. A new regime in heavy-ion collisions is pointed out to occur at ∼ 1 TeV. The pseudorapidity spectra of photons are also well reproduced within the proposed approach in the entire collision energy range and an explanation of their centrality independence is given. Predictions are made for the forthcoming higher-energy measurements in pp and heavy-ion collisions at the LHC.

Speaker: Aditya Nath Mishra (Indian Institute of Technology Indore (IN))

Aditya_WPCF2015.pdf

37 Model independent analysis of nearly Levy correlations in 1, 2 and 3 dimensions

Speaker: Tamas Novak (H)

wpcf2015-novak.pdf

wpcf2015-novak.pptx

38 Shadowing in Glauber models

The two component Monte-Carlo Glauber model predicts a knee-like structure in the centrality dependence of elliptic flow $v_2$ in Uranium+Uranium collisions at $\sqrt{S_{NN}}=193$ GeV. It also produces a strong anti-correlation between $v_2$ and $dN_{ch}/dy$ in the case of top ZDC events. However, none of these features have been observed in data. We address these discrepancies by including the effect of nucleon shadowing to the two component Monte-Carlo Glauber model. Apart from addressing successfully the above issues, we find that the nucleon shadow suppresses the event by event fluctuation of various quantities, e.g. $\varepsilon_2$ which is in accordance with expectation from the dynamical models of initial condition based on gluon saturation physics. Ref. arXiv: 1510.01311 [nucl-th]

Speaker: Sandeep Chatterjee (Variable Energy Cyclotron Centre)

sandeep.pdf

39 The role of the sigma meson in thermal models

The by now well-established scalar-isoscalar resonance f0(500) (the σ meson) seems potentially relevant in the evaluation of thermodynamic quantities of a hadronic gas, since its mass is low. However, we recall that its contribution to isospin-averaged observables is, to a surprising accuracy, canceled by the repulsion from the pion-pion scalar-isotensor channel. As a result, in practice one should not incorporate f0(500) in standard hadronic resonance-gas models for studies of isospin averaged quantities. In our analysis we use the formalism of the virial expansion, which allows one to calculate the thermal properties of an interacting hadron gas in terms of derivatives of the scattering phase shifts, hence in a model-independent way directly from experimentally accessible quantities. A similar cancellation mechanism occurs for the scalar kaonic interactions between the I=1/2 channel (containing the alleged K∗0(800) or the κ meson) and the I=3/2 channel.

Speaker: Prof. Francesco Giacosa (Kielce University)

giacosawpcf.pdf

10:40 Break

Session 12

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

40 Event shape analysis in ultrarelativistic nuclear collisions

We present a novel method for sorting events. So far, single variables like multiplicity or flow vector magnitude were used for sorting events. We present a method that takes into account the whole azimuthal angle distribution rather than a single variable. This method studies the angular distribution via the algorithm proposed in [1]. There, the algorithm was initially used for distinguishing good scientific authors from the bad ones using their citation record. We sort events according to their angular record. The algorithm compares and sorts different azimuthal angle histograms according to their similarity, using the Bayesian concept of probability. It allows us to determine the good measure of the event shape. Its simplicity allows many different ways of event analysis. Moreover, it provides a multiplicity-independent insight. The algorithm is implemented in a code entitled ESSTER and we present its functionality on simple examples. We discuss the advantages and disadvantages of this approach and the possible usage in femtoscopy and other more exclusive experimental studies. $[$1$]$ S. Lehmann, A.D.Jackson, B. Lautrup: Measures and Mismeasures of Scientific Quality, Arxiv: physics/0512238

Speaker: Renata Kopecna (CERN)

kopecren_warsaw_2015.pdf

41 Reproduction of fluctuations of flow harmonics in Pb+Pb collisions at sqrt(s)=2.76 TeV in the Glauber model

In the framework of the Glauber model, we compute fluctuations of flow harmonics with multi-bin cumulants in Pb+Pb collisions at the LHC energy of $\sqrt{s_{NN}}=2.76$~TeV. The model with wounded nucleons and the admixture of binary collisions leads to agreement with the experimental data from the ATLAS, ALICE, and CMS collaborations. The agreement becomes even better when negative binomial fluctuations for the particle production are overlaid over the Glauber sources.

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

mryb_wpcf_2015_4.pdf

42 Systematic studies of correlations between different order flow harmonics in Pb-Pb collisions at sqrt(s)=2.76 TeV

Dong Jo Kim for the ALICE Collaboration The collective expansion of the color-deconfined fireball created in ultra-relativistic heavy-ion collisions can map the initial state of the quark-gluon plasma (QGP) to the final-state particle spectrum. Due to quantum fluctuations of the positions of the constituents inside the colliding nuclei, the density of produced QGP is highly inhomogeneous in the plane transverse to the beam direction and fluctuates from event to event, even for collisions with identical impact parameters. Such inhomogeneities in the initial density lead to development of anisotropic pressure gradients, causing an anisotropic collective expansion of the fireball whose anisotropic flow magnitudes $v_n$ and associated symmetry planes $\Psi_n$ fluctuate from collision to collision. The magnitudes of higher-order harmonics are sensitive to the shear viscosity to entropy density ratio [1]. Further, the correlations between magnitudes of two different flow harmonics can give valuable additional insights to constrain initial conditions and the transport properties of the system produced in heavy-ion collisions. Both the magnitudes of individual flow harmonics and the correlations between magnitudes of two different flow harmonics have been investigated with the ALICE detector at the LHC. The results will be compared to the calculations from AMPT and hydrodynamic models. [1] Nucl.Phys. A904-905 (2013) 377c-380c

Speaker: Dong Jo Kim (University of Jyvaskyla (FI))

WPCF2015_djkim.pdf

43 An analytic hydrodynamical model of the effect of rotation on observables in heavy-ion collisions

Observing the rotation of the expansion tells new information on the equation of state of the strongly interacting quark gluon plasma produced in high energy heavy ion collisions. In this work we review a recently found exact and analytic solution of fireball hydrodynamics. Its unique space-time picture (it describes an expanding, rotating three-axis ellipsoid) makes it a perfect candidate to analytically investigate the effect of rotation on the observables. THe calculation of single-particle spectra and two-particle correlation functions (and related quantites) will be presented, and argued that the experimentally measurable angle between the eigenframe of the single-particle spectrum and that of the HBT correlations is a quantitative signature of rotation. The observables are calculated using simple exact analytic formulas. In the spirit of the successful Buda-Lund model, we will also show the straightforward generalization of our analytic non-relativistic results to a relativistic parametrization, that predicts realistic momentum dependence of the parameters of the HBT correlations.

Speaker: Marton Nagy (Eotvos Lorand University (HU))

2015-11-06-Csorgo-4-Nagy-Warsaw-WPCF2015.pdf

2015-11-06-Csorgo-4-Nagy-Warsaw-WPCF2015.pptx

12:40 Lunch

Session 13

Convener: Yuriy Sinyukov (Bogolyubov Institute for Theoretical Physics)

44 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 violate the viscous hydrodynamics assumption of small deviation from local equilibrium. They may lead to unphysical results, and, comparing to the exact 0+1 solutions of the Boltzmann equation, they often badly reproduce the longitudinal pressure (especially for initial stages) and provide the wrong asymptotic behavior. In order to more accurately treat systems possessing such large anisotropies, a new approach, called anisotropic hydrodynamics, was recently developed. In this approach, the pressure anisotropy is treated in a non perturbative manner at the leading order in the hydrodynamic expansion.  This allows one to match with second order viscous hydrodynamics in the close to equilibrium limit where viscous hydrodynamics is justified. We present the very latest prescription for the leading order of the anisotropic expansion. Differently from previous formulations it lacks any symmetry constraint on the space-time evolution, like longitudinal boost invariance or cylindrically symmetric radial flow. Therefore it can be used directly without the need of a next to leading order treatment for describing non trivial transverse dynamics. Checking numerically the agreement with the known solution of the Boltzmann equation in the Bjorken flow limit we found a very striking agreement, improving the already good agreement of previous 0+1 and 1+1 dimensional formulations. References [1] L. Tinti, Anisotropic matching principle for the hydrodynamics expansion, arXiv:1506.07164.

Speaker: Leonardo Tinti (Jan Kochanowski University)

Tinti_WPCF2015.pdf

45 Anisotropic hydrodynamics for a mixture of quark and gluon fluids

Relativistic hydrodynamics has been a fundamental tool to understand the evolution of matter in heavy-ion experiments at RICH and LHC. Despite the success of second order viscous hydrodynamics in reproducing collective behavior and particle spectra, there are still theoretical shortcomings that may question the validity of the approach in heavy-ion experiments conditions. Large gradients and fast longitudinal expansion produce very large pressure corrections, in contrast to the founding hypothesis of small deviation from local equilibrium and the perturbative treatment viscous corrections. One way to address this problem is anisotropic hydrodynamics. Most of the theoretical investigations about hydrodynamics started from a kinetic underlying substrate of a single species of particles. Unfortunately the striking agreement of anisotropic hydrodynamics with the exact solution of the Boltzmann equation was not preserved in the case of a mixtures of quarks and gluons. We recently extended the anisotropic hydrodynamics prescription for massless particles in 1+1-dimensions to the case of mixtures of fluids, largely improving the agreement with the exact solutions compared to previous works [1-3]. We allow quarks and gluons to have different momentum scales during the evolution and a non vanishing baryon chemical potential. We take the dynamical equations from the zeroth, the first and the second moment of the Boltzmann equation [4]. We performed a test of the new formulation, comparing the results of anisotropic hydorodynamics with the exact solution of the Boltzmann equation for a mixture of fluid in the Bjorken flow limit, finding a very good agreement [5]. [1] W.Florkowski, R.Maj, R.Ryblewski, M.Strickland, Phys.Rev.C87 (2013) 3, 034914. [2] W.Florkowski, R.Maj, Acta Phys.Polon.B44 (2013) 10, 2003-2017. [3] W.Florkowski, O.Madetko, Acta Phys.Polon.B45 (2014) 1103. [4] L.Tinti, W.Florkowski, Phys.Rev.C89 (2014) 3, 034907. [5] W.Florkowski, E.Maksymiuk, R.Ryblewski, L.Tinti arXiv:1508.04534

Speaker: Ewa Maksymiuk (Jan Kochanowski University)

Maksymiuk_WPCF2015.pdf

46 Highly-anisotropic hydrodynamics for central collisions

We use leading-order anisotropic hydrodynamics to study an azimuthally-symmetric boost invariant quark-gluon plasma. We impose a realistic lattice-based equation of state and perform self-consistent anisotropic freeze-out to hadronic degrees of freedom. We then compare our results for the full spatiotemporal evolution of the quark-gluon plasma and its subsequent freeze-out to results obtained using 1+1d Israel-Stewart second-order viscous hydrodynamics. We find that for small shear viscosities, 4πη/s ∼ 1, the two methods agree well for nucleus-nucleus collisions, however, for large shear viscosity to entropy density ratios or proton-nucleus collisions we find important corrections to the Israel-Stewart results for the final particle spectra and the total number of charged particles. Finally, we demonstrate that the total number of charged particles produced is a monotonically increasing function of 4πη/s in Israel-Stewart viscous hydrodynamics whereas in anisotropic hydrodynamics it has a maximum at 4πη/s ∼ 10. For all 4πη/s > 0, we find that for Pb-Pb collisions Israel-Stewart viscous hydrodynamics predicts more dissipative particle production than anisotropic hydrodynamics

Speaker: Dr Radoslaw Ryblewski (IFJ PAN)

talk.pdf

47 Flow and multiplicity correlations in pseudorapidity

Speaker: Piotr Bozek

wpcfbozek.pdf

15:30 Coffee Break

Session 14 - Common session with Nica Days

Convener: Andrzej Bialas

48 Rapidity fluctuations in the initial state

Recent data from the LHC suggest specific rapidity correlations between the observed hadrons. We propose a model of fluctuations in the initial state, incorporating fluctuation of the length of the emitting sources in rapidity, which is capable of describing the data. In particular, it reproduces the decorrelation of the event-plane angles (the torque effect) in Pb-Pb and p-Pb collisions.

Speaker: Wojciech Broniowski (IFJ PAN)

49 Thermalization, evolution and observables in integrated hydrokinetic model of A+A collisions

Speaker: Yuriy Sinyukov (Bogolyubov Institute for Theoretical Physics)

Sinyukov-NICA-2015-v2.pdf

50 Study QCD Phase Structure in High-Energy Nuclear Collisions

Speaker: Nu Xu (LBNL)

nxu_NICA_Day_Nov2015.pdf

nxu_NICA_Day_Nov2015.pdf

nxu_NICA_Day_Nov2015.pptx

51 Recent results from the NA61/SHINE programme on strong interactions

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

Gazdzicki_NICA_SEMINAR_WARSAW_2015.pdf

52 Searching for perfect fluid in ultracold fermionic gas

Speaker: Gabriel Wlazlowski (Warsaw University of Technology)

talk.pdf

Conference Banquet

Saturday 7 November

Session 15

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

53 ALICE looks forward: ALICE measurements of dNch/deta over a broad eta range

An overview of ALICE results on the charged--particle pseudorapidity density measured over a broad range ($|\eta|<5.0$) in \mbox{p--Pb} collisions at ${\sqrt{s_{\rm NN}}}=$5.02 TeV and \mbox{Pb--Pb} collisions at ${\sqrt{s_{\rm NN}}}=$2.76 TeV is presented. This includes extension of the previous measurements reported by ALICE into more peripheral collisions and with higher granularity for \mbox{Pb--Pb} and a broader $\eta$ range in \mbox{p--Pb}. The measurements in the forward regions are performed using the Forward Multiplicity Detector (FMD). The FMD signal is dominated by secondary particles produced in surrounding material necessitating the use of a data--driven approach to extract the primary charged-particle density. The results are compared to predictions from various models.

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

WPCFMChojnacki.pdf

54 PHENIX Levy analysis of Bose-Einstein correlation functions

Bose-Einstein or HBT correlations of identified charged particles provide insight into the space-time structure of particle emitting sources in heavy-ion collisions. The two-pion HBT correlation function strength (intercept parameter) and especially the transverse mass dependence of it (together with similar information from higher order correlation functions) may carry information on the core-halo structure of the source as well as on the possible coherent particle production. For a robust measurement of the intercept parameter, a source model beyond that of a Gaussian needs to be applied: we utilize Levy distributions, whose index of stability $\alpha$ may also yield information on the nature of the phase transition. The PHENIX experiment at RHIC collected data from $\sqrt{s_{NN}}= 200$ GeV Au+Au collisions in the 2010 running period. We present the latest status of the PHENIX measurement of two-pion Bose-Einstein correlations in this dataset, and the analysis of the Levy source parameters as a function of transverse momentum.

Speaker: Dániel Kincses (Eötvös Loránd University, PHENIX collaboration)

WPCF_kincsesd.pdf

55 Evolution of Temperature Fluctuation in a Thermal bath and, its Implications in Hadronic and Heavy-Ion Collisions

The evolution equation for inhomogeneous and anisotropic temperature fluctuations inside a medium is derived within the ambit of Boltzmann Transport Equation. Also, taking some existing realistic inputs we have analyzed the Fourier space variation of temperature fluctuation for the medium created after heavy-ion collisions. The effect of viscosity on the variation of fluctuations is investigated. Further, possible implications in hadronic and heavy-ion collisions are explored.

Speaker: Raghunath Sahoo (Indian Institute of Technology Indore (IN))

Evo_Tem_Fluct-RNS-WPCF.pdf

56 K0*(800) as a companion pole of K0*(1430)

We study the broad light scalar kaonic resonance $K_0^*(800)$ as a dynamically generated state. Namely, we show that this resonance emerges when investigating the heavier quark-antiquark scalar state $K_0^*(1430)$ dressed by quantum fluctuations with one kaon and one pion circulating in the loops. We analyse the spectral function in the whole kaonic sector up to 1.8 GeV and determine the position of the poles on the complex plane: $K_0^*(1430)$ corresponds to a standard 'seed' state, while $K_0^*(800)$ corresponds to a 'companion' additional pole.

Speaker: Milena Soltysiak (Jan Kochanowski University)

M.Soltysiak7nov.pdf

10:40 Coffee Break

Session 16

Convener: Dariusz Miskowiec (GSI Darmstadt)

57 Two identical pions correlations at small relative momenta in collisions of Al+Al and Ni+Ni at 1.9A GeV

The structure of the boson correlation function for expanding thermalized systems address the dimensions of the region of homogeneity, the size and shape of the phase space cloud of outgoing particles whose velocities have a specific magnitude and direction. Correlations of pion-pion pairs emitted in Al+Al and Ni+Ni collisions at beam energy of 1.9A GeV are investigated with the FOPI detector system at GSI Darmstadt [1]. Three-dimensional two identical pions relative momentum distributions are performed in the longitudinally co- moving system (LCMS). An effective 3-dimensional spatio-temporal source radius is obtained by fitting the 3-dimensional Gaussian function to the Coulomb corrected experimental pion-pion correlation function [2]. The behavior of the long-, out- and side-radii on system size, total kinetic energies and total transverse momentum of two coincident pions are studied. With increasing size of the colliding system the source radius are found to increase. This dependence is due to a larger number of participants in the collision zone. With increasing total kinetic energy and total transverse momentum of two coinciding particles the source radii become smaller. This dependence is consistent with the idea that nucleus-nucleus collisions are characterized by the collective expansion of nuclear matter after the compression phase. 3-dimensional radii of effective source extracted from two positive pion correlations is similar to the results of two negative pion correlations [3]. 1. W. Reisdorf et al., FOPI collaboration, Nucl. Phys. A 612 (1997) 493 2. D. H. Boal, Rev Mod Phys, 62 (2003) 533 3. S. V. Akkelin et al., Phys Let B, 356 (1993) 525

Speaker: Volha Charviakova (National Centre for Nuclear Research (PL))

wpcf2015.pdf

58 Like-sign kaons femtoscopy for the Beam Energy Scan program at STAR

Speaker: Martin Girard (Warsaw University of Technology)

WPCF2015_Girard.pdf

59 Two-particle proton correlations at BES energies

Proton femtoscopy.

Speaker: Sebastian Siejka (Warsaw University of Technology)

WPCF2015_Siejka.pdf

60 Two-particle correlations using THERMINATOR model for BES program

Speaker: Krzysztof Brzezinski (Warsaw University of Technology)

Brzezinskiprezentacja.pdf

61 Numerical analysis of background effects in identical pion femtoscopic correlations at the LHC

This presentation considers the femtoscopic analysis of identical pions performed on Monte Carlo data. The studies were conducted on the data set of proton-lead (p–Pb) collisions at the centre-of-mass energy √sNN = 5.02 TeV and proton-proton (pp) collisions at the centre-of-mass energy √sNN = 7 TeV, obtained from the two selected Monte Carlo event generators: EPOS ver. 3.076 and PYTHIA ver. 6.4 Perugia-0 tune. The analysis was carried out using the femtoscopy technique which allows to study the space-time size and structure of the particle emitting sources created during particle collisions. The behaviour of the femtoscopic correlation functions is determined by the several correlation sources which have to be taken into account while performing the analysis. For identically charged pairs of pions the most visible effect originates from the Bose-Einstein quantum statistics. The characteristic femtoscopic structure at low relative momentum is the result of this effect. However, the experimental measurements are difficult due to the presence of significant additional non-femtoscopic correlation sources, which distort the femtoscopic structure in the region of the femtoscopic effect. Minijets are the most probable hypothesis of the origin of these structures. The main goal of these studies is to propose and validate a method which best describes femtoscopic correlations with taking into account non-femtoscopic effects in the extraction of the femtoscopic information in pp and p–Pb collisions.

Speaker: Przemyslaw Karczmarczyk (Warsaw University of Technology (PL))

WPCF_07.11.2015.pdf

Conference closing and next WPCF