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Measured moments of the multiplicity distribution for a given sort of particles are used in the literature for the determination of the phase transition parameters of hot QCD matter in ultrarelativistic heavy-ion collisions. We argue that the subsequent cooling in the hadronic phase, however, may drive the multiplicity distribution out of equilibrium. We use a master equation for the description of the evolution of the multiplicity distribution to demonstrate how the different moments depart away from their equilibrium values. If such moments were measured and interpreted as if they were equilibrated, one would obtain different apparent temperatures from different moments.

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The HADES (High Acceptance DiElectron Spectrometer) experiment at the SIS18 accelerator of the GSI Helmholtzzentrum für Schwerionenforschung investigates heavy-ion collisions at kinetic beam energies of a few GeV per nucleon. We have carried out a detailed moment analysis of (net-)proton distributions of Au+Au collisions with 1.23A GeV (). We present here the correction techniques used in this investigation.

A kinetic master equation for multiplicity distributions is formulated for charged particles which are created or destroyed only in pairs due to the conservation of their Abelian charge. It allows one to study time evolution of the multiplicity distributions in a relativistic many-body system with arbitrary average particle multiplicities. It is shown to reproduce the equilibrium results for both canonical (rare particles) and grand canonical (abundant particles) systems. For canonical systems, the equilibrium multiplicity is much lower and the relaxation time is much shorter than the naive extrapolation from grand canonical results. Implications for chemical equilibration in heavy-ion collisions are also discussed.

The correlation between baryon number and strangeness elucidates the nature of strongly interacting matter. This diagnostic can be extracted theoretically from lattice QCD calculations and experimentally from event-by-event fluctuations. The analysis of present lattice results above the critical temperature severely limits the presence of q over(q, -) bound states, thus supporting a picture of independent (quasi)quarks. Details may be found in [V. Koch, A. Majumder and J. Randrup, arXiv:nucl-th/0505052, Phys. Rev. Lett. in print].

The event-by-event fluctuations of identified particles in ultrarelativistic nucleus-nucleus collisions give information about the state of matter created in these collisions as well as the phase diagram of nuclear matter. In this proceedings, we present the latest results from ALICE on the centrality and pseudorapidity dependence of net-proton fluctuations, which are closely related to net-baryon fluctuations, as well as net-kaon and net-pion fluctuations. The effects of volume fluctuations and global baryon conservation on these observables are discussed. Furthermore, the correlated fluctuations between different particle species, quantified by the observable $\nu_{dyn}$, are also shown as functions of multiplicity and collision energy and are compared with Monte Carlo models. These measurements are performed in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 2.76$ TeV using the novel Identity Method and take advantage of the excellent particle identification capabilities of ALICE.

The K+ production is studied for the p + NaF, Ne + NaF, Ne + Pb systems at 2.1 GeV/A in the frame of a 3-dimensional cascade model. Owing to the small elementary production cross sections, the K+ production is calculated perturbatively. Two kinds of production processes are introduced: baryon-baryon collisions leading to three-particle final states, and pion-nucleon collisions leading to two-body final states. The time evolution of the two processes is studied. The integrated K+ cross sections are in good agreement with the experimental data. The contribution of the πN induced mechanism is of the order of 25% for Ne + NaF, but increases with the size of the system. Scaling properties are discussed. A simple rescattering model is used to calculate the invariant cross section for the Ne + NaF case. Good agreement with experiment is obtained, except at forward angles.

A different type of fluctuations in the multiplicities and momentum distributions of particles emitted in relativistic heavy-ion collisions is considered. These fluctuations are sensitive to the microscopic structure of the dense matter. The fluctuations of locally observed quantities that show a distinctly different behavior in a hadron gas (HG) and a quark-gluon plasma (QGP) was considered since the expansion is too fast for local fluctuations to follow the mean thermodynamic evolution of the system.

We argue that the event-by-event fluctuation of the proton number is a meaningful and promising observable for the purpose of detecting the QCD critical end point in heavy-ion collision experiments. The long range fluctuation of the order parameter induces a characteristic correlation between protons which can be measured. The proton fluctuation also manifests itself as anomalous enhancement of charge fluctuations near the end point, which might be already seen in existing data.

- S Ejiri
- F Karsch
- K Redlich

S. Ejiri, F. Karsch and K. Redlich, Phys. Lett.
B 633, 275 (2006) doi:10.1016/j.physletb.2005.11.083
[hep-ph/0509051].

- B Stokic
- B Friman
- K Redlich

B. Stokic, B. Friman and K. Redlich, Phys. Lett.
B 673, 192 (2009) doi:10.1016/j.physletb.2009.02.018
[arXiv:0809.3129 [hep-ph]].

- C Athanasiou
- K Rajagopal
- M Stephanov

C.
Athanasiou,
K.
Rajagopal
and
M. Stephanov, Phys. Rev. D 82, 074008 (2010)
doi:10.1103/PhysRevD.82.074008
[arXiv:1006.4636
[hep-ph]].

- R V Gavai
- S Gupta

R. V. Gavai and S. Gupta, Phys. Lett. B 696, 459 (2011)
doi:10.1016/j.physletb.2011.01.006
[arXiv:1001.3796
[hep-lat]].

- M A Stephanov

M. A. Stephanov, Phys. Rev. Lett. 107, 052301 (2011)
doi:10.1103/PhysRevLett.107.052301 [arXiv:1104.1627
[hep-ph]].

- S Gupta
- X Luo
- B Mohanty
- H G Ritter
- N Xu

S. Gupta, X. Luo, B. Mohanty, H. G. Ritter and N. Xu,
Science 332, 1525 (2011) doi:10.1126/science.1204621
[arXiv:1105.3934 [hep-ph]].

- M A Stephanov

M. A. Stephanov, Phys. Rev. Lett. 102, 032301 (2009)
doi:10.1103/PhysRevLett.102.032301 [arXiv:0809.3450
[hep-ph]].

- A Bazavov

A.
Bazavov
et al.
[HotQCD
Collaboration],
Phys. Rev. D 96,
no. 7,
074510 (2017)
doi:10.1103/PhysRevD.96.074510
[arXiv:1708.04897
[hep-lat]].

- L Adamczyk

L.
Adamczyk
et
al.
[STAR
Collaboration],
Phys. Rev. Lett. 112,
032302 (2014)
doi:10.1103/PhysRevLett.112.032302 [arXiv:1309.5681
[nucl-ex]].

- M Szala

M. Szala et al. [HADES Collaboration], J. Phys. Conf.
Ser. 1024, no. 1, 012024 (2018). doi:10.1088/17426596/1024/1/012024

- M Kitazawa
- M Asakawa

M. Kitazawa and M. Asakawa, Phys. Rev. C 86,
024904 (2012) Erratum: [Phys. Rev. C 86, 069902
(2012)] doi:10.1103/PhysRevC.86.024904, 10.1103/Phys-RevC.86.069902 [arXiv:1205.3292 [nucl-th]].

- P Alba
- W Alberico
- R Bellwied
- M Bluhm
- V Sarti
- M Nahrgang
- C Ratti

P. Alba, W. Alberico, R. Bellwied, M. Bluhm, V. Mantovani Sarti, M. Nahrgang and C. Ratti, Phys. Lett.
B 738, 305 (2014) doi:10.1016/j.physletb.2014.09.052
[arXiv:1403.4903 [hep-ph]].

- M A Stephanov

M. A. Stephanov, Phys. Rev. D 81, 054012 (2010)
doi:10.1103/PhysRevD.81.054012 [arXiv:0911.1772 [hepph]].

- S Jeon
- V Koch
- K Redlich
- X N Wang

S. Jeon, V. Koch, K. Redlich and X. N. Wang,
Nucl. Phys. A 697, 546 (2002) doi:10.1016/S0375-9474(01)01228-3 [nucl-th/0105035].

- R Bellwied
- J Noronha-Hostler
- P Parotto
- I Vazquez
- C Ratti
- J M Stafford

R. Bellwied, J. Noronha-Hostler, P. Parotto, I. Portillo
Vazquez, C. Ratti and J. M. Stafford, arXiv:1805.00088
[hep-ph].

- M Bluhm
- M Nahrgang

M. Bluhm and M. Nahrgang, arXiv:1806.04499 [nucl-th].

- A Andronic
- P Braun-Munzinger
- K Redlich
- J Stachel

A. Andronic, P. Braun-Munzinger, K. Redlich and
J. Stachel, arXiv:1710.09425 [nucl-th].

- L Adamczyk

L.
Adamczyk
et
al.
[STAR
Collaboration],
arXiv:1709.00773 [nucl-ex].