### Conveners

#### Collective dynamics: 1

- Takeshi Kodama (Universidade Federal do Rio de Janeiro)

#### Collective dynamics: 2

- Laszlo Csernai (Department of Physics and Technology)

#### Collective dynamics: 3

- Barbara Erazmus (CNRS/IN2P3)

#### Collective dynamics: 4

- Guy Paic (Universidad Nacional Autonoma (MX))

Ramiro Rolando Debbe Velasco
(Brookhaven National Laboratory (US))

5/19/14, 11:00 AM

Collective Dynamics

Contributed Talk

Proton-lead collisions at the LHC provide an opportunity to probe the
physics of the initial state of ultra-relativistic heavy ion
collisions. In particular, they can provide insight on the effect
of an extended nuclear target on the dynamics of soft and hard
scattering processes and subsequent particle production. Charged
particle multiplicity and pseudorapidity distributions are...

Michael Tannenbaum
(Brookhaven National Laboratory (US))

5/19/14, 11:20 AM

Collective Dynamics

Contributed Talk

Measurements of the midrapidity transverse energy distribution
$dE_T/d\eta$, are presented for $p$$+$$p$, $d$$+$Au, and Au$+$Au
collisions at 62.4--200 GeV. The $E_T$ distributions are compared with
the number of participants, $N_{\mathrm{part}}$, the number of binary
collisions, $N_{\mathrm{coll}}$, and the number of constituent-quark
participants, $N_{qp}$, calculated from a Glauber...

Piotr Bozek

5/19/14, 11:40 AM

Collective Dynamics

Contributed Talk

The collective expansion of the fireball formed in ultrarelativistic p-A and d-A collisions are discussed. Estimates based on the extrapolation of the hydrodynamic model from A-A collisions to small systems indicate possible formation of a dense droplet of matter. Fluctuation in the initial state lead to finite eccentricity and triangularity, which give measurable elliptic and triangular flow...

Cristian Andrei
(IFIN-HH Bucharest (RO))

5/19/14, 12:00 PM

Collective Dynamics

Contributed Talk

Comprehensive results on transverse momentum distributions, their ratios, d$N$/d$y$ and <$p_{\mathrm{T}}$> values for identified light flavor hadrons ($\pi$, K, p, $\Lambda$, $\Xi$, $\Omega$) at low $p_{\mathrm{T}}$ and mid rapidity are reported for all collision systems at LHC energies: pp, p-Pb, Pb-Pb. It is well known that strong collective effects are observed in central Pb-Pb collisions...

Sarah Campbell
(Iowa State University)

5/19/14, 12:20 PM

Collective Dynamics

Contributed Talk

In this talk the transverse momentum spectra of identified particles, geometry categorization and bias, and global observables in d+Au collisions at 200 GeV are reported. In d+Au collisions, the intermediate $p_T$ region between 2 and 5 GeV, there is a significant enhancement of the baryon to meson ratios relative to those measured in p+p collisions. The enhancement is present in d+Au...

Edward Shuryak
(stony brook university)

5/19/14, 12:40 PM

Collective Dynamics

Contributed Talk

With growing multiplicity, the pp and pA collisions enter the domain where the macroscopic description (thermodynamics and hydrodynamics) becomes applicable. We discuss this situation, first with simplified thought experiments, then
with some idealized representative cases, and finally address the real data.
For clarity, we don't do it numerically but analytically, using the Gubser solution....

Roy Lacey
(Stony Brook University)

5/19/14, 2:20 PM

QCD Phase Diagram

Contributed Talk

The flow harmonics $v_{2,3}$ for charged hadrons, are studied for a broad range of centrality selections and beam collision energies in Au+Au ($\sqrt{s_{NN}}= 7.7 - 200$ GeV) and Pb+Pb ($\sqrt{s_{NN}}= 2.76$ TeV) collisions. They validate the characteristic signature expected for the system size dependence of viscous damping at each collision energy studied. The extracted viscous coefficients,...

Alexandru Florin Dobrin
(University of Utrecht (NL))

5/19/14, 2:40 PM

Collective Dynamics

Contributed Talk

We report the measurements of elliptic flow for identified particles produced in Pb--Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV with the ALICE detector at the LHC.
The second Fourier coefficient, $v_2$, measured with the scalar product method with a large pseudo-rapidity gap of $|\Delta\eta| > 2.0$, is reported for $\pi$, ${\rm K}^{\pm}$, ${\rm K}^0_s$, p ($\overline{\mathrm{p}}$),...

Md. Rihan Haque
(V)

5/19/14, 3:00 PM

Collective Dynamics

Contributed Talk

A strongly interacting medium, namely Quark Gluon Plasma (QGP), is formed in high energy heavy ion collisions at RHIC. Elliptic flow $(v_{2})$, the second order Fourier coefficient of azimuthal distribution of the produced particles with respect to reaction plane, is used to investigate the properties of QGP. Light nuclei ($d$, $\bar{d}$, $t$, $^{\small{3}}He$), produced in such collisions,...

Ulrich Heinz
(The Ohio State University)

5/19/14, 3:20 PM

Collective Dynamics

Contributed Talk

The collective expansion in relativistic heavy-ion collisions is initially highly anisotropic. Due to viscosity, this leads to strongly deformed local momentum distributions which invalidates the standard viscous hydrodynamic expansion around a local equilibrium distribution, causing a breakdown of viscous fluid dynamics à la Israel and Stewart at early times. We have developed an improved...

Dr
Gabriel Denicol
(McGill University)

5/19/14, 3:40 PM

Collective Dynamics

Contributed Talk

Currently, most fluid-dynamical simulations of relativistic heavy ion collisions take into account only dissipative effects originating from shear viscosity. However, there is no a priori reason to neglect bulk viscosity since the actual order of magnitude and temperature dependence of this transport coefficient is unknown, and could be significant. In this work, we explore the...

Anthony Robert Timmins
(University of Houston (US))

5/19/14, 4:30 PM

Collective Dynamics

Contributed Talk

A key question facing the heavy-ion physics community is whether or not collective behavior develops in elementary collisions. We will utilize a variety of techniques designed to obtain elliptic and triangular flow coefficients ($v_{2}$ and $v_{3}$) on data from pp $\sqrt{s} = 7$ TeV and p-Pb $\sqrt{s_{\rm NN}} = 5.02$ TeV collisions. We will report new measurements of second, fourth, and...

Dr
Gokce Basar
(Stony Brook University)

5/19/14, 4:50 PM

Collective Dynamics

Contributed Talk

I compare the flow-like correlations in high multiplicity proton-nucleus (p + A) and nucleus- nucleus (A + A) collisions. At fixed multiplicity, the correlations in these two colliding systems are strikingly similar, although though the system size in p + A is smaller. Based on an independent cluster model and a simple conformal scaling argument, where the ratio of the mean free path to the...

Hiroshi Nakagomi
(Tsukuba University)

5/19/14, 5:10 PM

Collective Dynamics

Contributed Talk

Cu$+$Au collisions at RHIC have provided the first asymmetric
heavy-ion collisions at collider energies, where it is generally
believed that nuclear matter above the Quark-Gluon Plasma (QGP) transition is created. The
Cu$+$Au system provides a unique arena for QGP production and
development with novel features that are inaccessible in symmetric
A$+$A collisions, such as intrinsic...

Florian Senzel
(Goethe-Universität Frankfurt)

5/19/14, 5:30 PM

Collective Dynamics

Contributed Talk

An updated version of the partonic transport model Boltzmann Approach to Multi-Parton Scatterings (BAMPS) is presented, which numerically solves the 3+1D Boltzmann equation by allowing interactions among all parton species: gluons, light quarks, and heavy quarks with both elastic and inelastic collisions. We introduce the improved Gunion-Bertsch matrix element, which cures problems of the...

Paul Romatschke
(U)

5/19/14, 5:50 PM

Collective Dynamics

Contributed Talk

Recent results in d+Au and p+Pb collisions at RHIC and the LHC provide evidence for collective expansion and flow of the created medium. We propose a control set of experiments to directly compare particle emission patterns from p+Au, d+Au, and He3+Au or t+Au collisions at the same sqrt(sNN). Using Monte Carlo Glauber we find that a He3 or triton projectile, with a realistic wavefunction...

Prof.
Miklos Gyulassy
(Columbia University)

5/19/14, 6:10 PM

Collective Dynamics

Contributed Talk

Recent low pT<2 GeV vn data on the beam energy scan (BES) and D+Au at RHIC and the surprising data on low pT vn in p+Pb at LHC challenge long held assumptions about the validity or necessity of perfect fluid hydrodynamics in A+A. Could classical field interference phenomena from color antenna arrays and or Unruh noninertial color currents play a critical role in resolving the BES+DA+pA puzzle?...

You Zhou
(NIKHEF and University of Utrecht (NL))

5/20/14, 9:00 AM

Collective Dynamics

Contributed Talk

Anisotropic azimuthal correlations are used to probe the properties and the evolution of the system created in heavy-ion collisions.
Hydrodynamic model calculations predict that there are effects of $p_{\rm T}$ dependent fluctuations of the flow angle and flow magnitude, which might bias our previous anisotropic flow measurements.
In this talk, the two effects will be investigated in both...

Damir Devetak
(University of Belgrade (RS))

5/20/14, 9:20 AM

Collective Dynamics

Contributed Talk

The technique of two-particle correlations has been widely used in studying flow via azimuthal anisotropy in relativistic heavy-ion collisions. A key assumption imposed in this approach is the factorization of Fourier coefficients extracted from two-particle correlations into a product of single-particle anisotropies of trigger and associated particles. It was recently predicted by...

Soumya Mohapatra
(State University of New York (US))

5/20/14, 9:40 AM

Collective Dynamics

Contributed Talk

Measurements of the distributions of event-by-event flow harmonics $v_n$
and the correlations between harmonics $v_n$ and $v_m$ of different
orders in $\sqrt{s_{NN}}=2.76$ TeV Pb+Pb collisions are presented. These
measurements give insight into the nature of fluctuations in the initial
geometry and the role of linear and non-linear hydrodynamic response to
the fluctuations, the latter can...

Stefan Floerchinger
(CERN)

5/20/14, 10:00 AM

Collective Dynamics

Contributed Talk

Initial fluctuations in hydrodynamic fields such as energy density or flow velocity give access to understanding initial state and equilibration physics as well as thermodynamic and transport properties. We provide evidence that the fluid dynamic propagation of fluctuations of realistic size can be based on a background-fluctuation splitting and a systematic perturbative expansion in the...

Ms
Valentina Rolando
(Università di Ferrara, INFN Ferrara)

5/20/14, 10:20 AM

Collective Dynamics

Contributed Talk

We present a numerical code for modeling relativistic heavy ion
collisions, ECHO-QGP. The code includes relativistic hydrodynamics
with dissipative terms and implements Israel-Stewart theory
in 3+1 D. Initial conditions are provided through an implementation
of the Glauber model (both Optical and Monte Carlo), while freezeout
and particle generation is based on the Cooper-Frye...