Melting Hadrons, Boiling Quarks

The kurtosis and skewness of net baryon-number fluctuations are studied for the magnetized phase diagram of three-flavor quark matter within the Polyakov extended Nambu-Jona-Lasinio model. Two models with magnetic catalysis and inverse magnetic catalysis are considered. Special attention is given to their behavior in the neighborhood of the light and strange critical end points (CEPs). Several isentropic trajectories that come close the CEPs are studied in order to analyze possible signatures of a CEP in the presence of external magnetic fields. The effect of the magnetic field on the velocity of sound, v 2 s , when both the light and strange CEPs are approached from the crossover region is also investigated by calculating their temperature and baryon chemical potential dependencies at fixed distances from these CEPs. Regions with large fluctuations but no CEP in nonmagnetized matter develop a CEP under the action of a strong magnetic field. Besides, the Landau quantization of the quark trajectories may result in the appearance of extra CEPs, in particular, in the strange sector for strong magnetic fields, identifiable by the net baryon-number fluctuations. Stiffer (smoother) fluctuations in the region of the CEP are characteristic of models that do not predict (do predict) the inverse magnetic catalysis at zero chemical potential. Particularly interesting is the ratio χ 4 B /χ 2 B that has a more pronounced peak structure, indicating that it is eventually a more convenient probe for the search of a CEP. The speed of sound shows a much richer structure in magnetized quark matter and allows one to identify both chiral and deconfinement transitions.

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“…The sound velocity, v 2 s = ∂P/∂E, is a fundamental quantity in the expansion of hot and dense matter [68].…”

Section: Resultsmentioning

confidence: 99%

Net baryon-number fluctuations in magnetized quark matter

2018

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“…We just briefly remind that in the GCE formulation of the HRG model the conserved charges, such as net baryon number B, electric charge Q, and strangeness S, are conserved on average, but can differ from one microscopic state to another. The fitting parameters in GCE HRG are the temperature T , baryon chemical potential µ B 1 , the system volume V , and the strangeness saturation parameter γ S [24][25][26].…”

Section: Hadron Resonance Gas Modelmentioning

confidence: 99%

Statistical hadron-gas treatment of systems created in proton-proton interactions at energies available at the CERN Super Proton Synchrotron

et al. 2018

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We analyze the newest data from the NA61/SHINE collaboration which, in addition to previous results on pions and kaons, include mean multiplicities of p, Λ, and φ-mesons produced in inelastic proton-proton (p+p) interactions at √ s N N = 6.3 − 17.3 GeV. The canonical ensemble formulation of the ideal hadron resonance gas (HRG) model is used with exact conservation of net baryon number B = 2, electric charge Q = 2, and strangeness S = 0. The chemical freeze-out parameters in p+p interactions are obtained and compared to those in central nucleus-nucleus collisions. Several features of p+p interactions at the CERN SPS within a statistical model are studied: 1) the inclusion of the φ-meson yields in thermal fits worsens significantly the fit quality; 2) the data show large event-by-event multiplicity fluctuations in inelastic p+p interactions which can not be explained by a single fireball described by a statistical model; 3) the fits within the canonical ensemble formulation of HRG do not give any improvement over the fits within the grand canonical ensemble formulation, i.e., there are no indications for existence of a single statistical system in p+p inelastic interactions in the considered energy range. PACS numbers: 25.75.-q, 25.75.Dw, 24.10.Pa

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“…Note that the 1/σ EP corrections are relatively minor for v 2 , but depend very strongly on centrality, while they can be a factor of 5 or higher for v 3 . That means that the actual modulations v raw n measured in the experiments are sometimes quite small and often similar across centralities 75 . Using two or more EP detectors with different resolutions (and still getting consistent results) alleviates some of these concerns.…”

Section: B the Devil's Advocatementioning

confidence: 93%

“…The dispersion between the experimentally reconstructed Ψn and the true Φn of the underlying distribution[322] 75. Of course from a purely mathematical point of view the procedure is correct, but the critical reader of experimental papers should be aware that the final results are small measured numbers subject to large corrections.…”

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confidence: 99%

Direct real photons in relativistic heavy ion collisions

David

2020

Rep. Prog. Phys.

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Direct real photons are arguably the most versatile tools to study relativistic heavy ion collisions. They are produced, by various mechanisms, during the entire space-time history of the strongly interacting system. Also, being colorless, most the time they escape without further interaction, i.e. they are penetrating probes. This makes them rich in information, but hard to decypher and interpret. This review presents the experimental and theoretical developments related to direct real photons since the 1970s, with a special emphasis on the recently emerged "direct photon puzzle", the simultaneous presence of large yields and strong azimuthal asymmetries of photons in heavy ion collisions, an observation that so far eluded full and coherent explanation. CONTENTS arXiv:1907.08893v1 [nucl-ex] 21 Jul 2019 21. Hydrodynamical models 48 2. Initial state, (fast) thermalization 50 3. Transport calculations 50 4. Other ideas 52 VII. Concluding remarks 54 VIII. Acknowledgements 55 References 56 3 I. INTRODUCTIONThe centuries old quest to reveal the "ultimate" constituents of matter and the laws of Nature governing them, and the realization from quantum mechanics that mapping smaller and smaller objects requires ever larger energy probes, made high energy physics one of the dominant scientific disciplines of the XXth century. At first we took advantage of the Universe as an "accelerator" providing high energy probes (cloud chamber and emulsion experiments), but soon we started to build our own accelerators, constantly increasing their energy and luminosity. The most spectacular and best known results came in elementary particle physics, but astrophysics and nuclear physics were a close second, benefiting enormously from the progress in experimental and theoretical tools. The central question in particle physics was the substructure of hadrons and the nature of confinement, while high energy nuclear physics' foremost concern was the behavior of high density nuclear matter, including its collectivity and possible phase transition into partonic matter, which in turn evoked the early stages of the Universe. Albeit particle and nuclear physics came with different perspectives, both were concerned with the strong interaction and its underlying theory, quantum chromodynamics (QCD), so the birth of a new discipline at their intersection, relativistic heavy ion physics, was almost inevitable. From Princeton and Berkeley to Dubna the race for larger and larger ions, energies and luminosities was on. Hadrons and nuclear fragments were studied extensively, and the applicability of thermo-and hydrodynamics gradually recognized. An excellent review of these first facilities and early developments -both experimental and theoretical -can be found in [1] by Goldhaber, while a (literally) insightful account of the genesis and achievements of RHIC and LHC was given by Baym in [2].Although lepton and photon production in hadronic and nuclear collisions was studied almost since the birth of quantum mechanics and quantum electrodynamics [3][4][...

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Melting Hadrons, Boiling Quarks

Cited by 6 publications

References 118 publications

Net baryon-number fluctuations in magnetized quark matter

Net baryon-number fluctuations in magnetized quark matter

Statistical hadron-gas treatment of systems created in proton-proton interactions at energies available at the CERN Super Proton Synchrotron

Direct real photons in relativistic heavy ion collisions

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