### Conveners

#### Correlations and fluctuations: I

- Jacquelyn Noronha-Hostler (University of Houston)

#### Correlations and fluctuations: II

- Frederique Grassi

#### Correlations and fluctuations: III

- Tapan Nayak (CERN, Geneva and VECC, Kolkata)

We study the critical properties of net-baryon-number fluctuations at the chiral restoration transition in a medium at finite temperature and net baryon density. The chiral dynamics of QCD is modeled by the Polykov-loop-extended Quark-Meson Lagrangian with the coupling of quarks to vector mesons. The Functional Renormalization Group is employed to properly account for the scaling properties...

The fluctuations of conserved charges - such as electric charge, strangeness, or baryon number - in ultrarelativistic heavy-ion collisions provide insights into the properties of the hot and dense matter produced as well as the QCD phase diagram. They can be related to the moments of the multiplicity distributions of identified particles. We extend the previous and ongoing measurements of the...

We present a lattice calculation on the cross-correlations of conserved charges

(baryon number, electric charge and strangeness) near the transition

temperature. We extrapolate to small baryo-chemical potentials, and thus we

cover typical STAR energies. We confront our finding to the latest STAR date

set on cross-correlations. In this work we use continuum lattice results with

resolution up to Nt=16.

We develop, within a canonical formulation of statistical mechanics, a systematic procedure to evaluate fluctuations of conserved quantities, such as baryon number, measured within an experimental acceptance. In nearly all experiments the baryon number fluctuations are approximated by the corresponding signals for net-proton measurements. We will discuss the validity and, in particular, the...

We propose that rapidity dependent momentum correlations can be used to extract the shear relaxation time $\tau_\pi$ of the medium formed in high energy nuclear collisions. The stress-energy tensor in an equilibrium quark-gluon plasma is isotropic, but in nuclear collisions it is likely very far from this state. The relaxation time $\tau_\pi$ characterizes the rate of isotropization and is a...

In ultrarelativistic heavy-ion collisions, correlations of particles with opposite quantum numbers provide insight into charge creation mechanisms, the time scales of quark production, collective motion of the QGP, and re-scattering in the hadronic phase. The longitudinal and azimuthal widths of general charge balance functions for pions, kaons, and protons are used to examine the two-wave...

We present a novel approach to the treatment of thermal fluctuations in the (3+1)-D viscous hydrodynamic simulation MUSIC. We investigate the phenomenological impact of thermal fluctuations on hadronic and electromagnetic observables using the state-of-the-art IP-Glasma + hydrodynamics + hadronic cascade hybrid approach [1]. In particular, we show that these thermal fluctuations influence the...

Multi-particle flow correlations in Pb+Pb collisions provide unique insight into the nature of event-by-event fluctuations of the initial eccentricity as well as final state dynamics in the transverse and longitudinal directions. This talk presents a detailed study of transverse flow fluctuations using 4 and 6-particle cumulants $v_n\{4\}$ and $v_n\{6\}$ for $n=1, 2, 3$, and 4. This includes...

In relativistic heavy-ion collisions, event-by-event fluctuations in the transverse plane in the initial states of quark-gluon plasma (QGP) could lead to anisotropic flows of the final hardons, which has been successfully described by relativistic hydrodynamics simulation. On the other hand, the initial states fluctuations in the longitudinal direction could lead to the fluctuations and...

Detailed measurements of collectivity in Au+Au collisions at RHIC provide a key

connection between the initial geometry of the deposited energy and the

hydrodynamic evolution of the medium. Utilizing the PHENIX silicon detectors, we present new measurements of flow coefficients extending over a wide range in pseudorapidity $-3 < \eta < 3 $ and to higher $p_T$. Over a broad range in...

Longitudinal harmonic flow decorrelation (the "torque" effect [1,2]) is a sensitive probe of the early dynamics of ultra-relativistic nuclear collisions. We propose new decorrelation measures of flow magnitude and event-plane angles and apply them to Pb+Pb collisions at the LHC, modeled via event-by-event hydrodynamic simulations. The basic purpose is to verify a generic feature, namely, that...

Fluctuations have been playing an important role in understanding observables in high-energy nuclear collisions. Higher harmonics of azimuthal angle distributions, for example, can be attributed to initial fluctuations of transverse profile from event to event. In this presentation, we focus on thermal fluctuations during hydrodynamic evolution (a.k.a. hydrodynamic fluctuations) of the QGP...

In relativistic high energy collisions, hard scattered partons can fragment into two back-to-back jets. These jets can be used as hard probes to study properties of the Quark Gluon Plasma created in nucleus-nucleus collisions. Di-hadron correlations with respect to high $p_T$ trigger particles are a useful tool to study the interactions between jets and the medium in high-energy heavy-ion...

LHCb offers the unique opportunity to perform correlation and production measurements in the light-flavour sector at forward rapidity. The measurement of the dihadron correlation as function of pseudorapidity eta and azimuthal angle phi in pp at sqrt(s)=13 TeV will be shown. The measurement will be put into context with the pPb ridge result by LHCb and will expand our knowledge on collective...

Results are presented for femtoscopic correlations with charged pion-kaon and identical pion-pion pairs measured with ALICE for Pb-Pb collisions at $\sqrt{s_{NN}}=$ 2.76 and 5.02 TeV. Three-dimensional femtoscopic analyses were performed for both systems in different transverse-momentum intervals and for different centrality classes. The source radius and the correlation strength parameter for...

In heavy-ion collision experiments, the centrality of a collision is defined according to the transverse energy or number of tracks observed in a given detector. We propose a procedure to relate this experiment-defined centrality to the true centrality of the collision, defined according to impact parameter, in a way which does not need require the introduction of a Glauber model or the...

Geometry and dynamics of the particle-emitting source in heavy-ion collisions at high energies can be inferred via femtoscopy method. Two-particle correlations at small relative momentum exploit Quantum Statistics and the Final State Interactions which allow one to study the space-time characteristics of the source of the order of $10^{-15}$ m and $10^{-23}$ s, respectively. The RHIC Beam...

Two-particle number and transverse momentum correlations are powerful tools for studying the medium produced in heavy-ion collisions. Correlations in the angular separation of pairs of hadrons can provide information on the medium transport characteristics. In particular, the transverse momentum correlations are sensitive to momentum currents, and provide information about the system life...