Under‐saturation of quarks at early stages of relativistic nuclear collisions: The hot glue initial scenario and its observable signatures

Stöcker, H.; Beitel, M.; Bı́ró, Tamás; Csernai, L. P.; Gallmeister, K.; Gorenstein, M. I.; Greiner, Carsten; Mishustin, I. N.; Panero, Marco; Raha, S.; Satarov, L. M.; Schramm, Stefan; Senzel, Florian; Sinha, Bikash; Steinheimer, Jan; Struckmeier, Jürgen; Vovchenko, Volodymyr; Xu, Zhe; Zhou, Kai; Zhuang, Pengfei

doi:10.1002/asna.201512252

Cited by 16 publications

(20 citation statements)

References 42 publications

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“…However, no precise answer about the fugacity dependence could be given up to now. Other studies [82,[84][85][86][87] give slightly different pictures, but we shall not elaborate on this topic here. Common ground is a quark fugacity λ q which is lower than unity and may or may not approach it within the lifetime of the fireball.…”

Section: Photon Rate At Nontrivial Quark Fugacitiesmentioning

confidence: 97%

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Nonequilibrium photon production in partonic transport simulations

et al. 2017

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We discuss the implementation of leading-order photon production in nonequilibrium partonic transport simulations. In this framework photons are produced by microscopic scatterings, where we include the exact matrix elements of Compton scattering, quark-antiquark annihilation, and bremsstrahlung processes. We show how the hard-thermal loop inspired screening of propagators has to be modified such that the microscopic production rate agrees well with the analytically known resummed leading-order rate. We model the complete quark-gluon plasma phase of heavy-ion collisions by using the partonic transport approach called the Boltzmann approach to multiparton scatterings (BAMPS), which solves the ultrarelativistic Boltzmann equation with Monte Carlo methods. We show photon spectra and elliptic flow of photons from BAMPS and discuss nonequilibrium effects. Due to the slow quark chemical equilibration in BAMPS, the yield is lower than the results from other groups; in turn we see a strong effect from scatterings of energetic jet-like partons with the medium. This nonequilibrium photon production can dominate the thermal emission, such that the spectra are harder and the photonic elliptic flow of the quark-gluon plasma becomes negative.Comment: 20 pages, 24 figures. Revised version as accepted by PR

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Section: Photon Rate At Nontrivial Quark Fugacitiesmentioning

confidence: 97%

“…The initial state is still uncertain, especially the quark and gluon content is under debate. It is commonly believed, that gluons are saturated or over-saturated [82], and quark-antiquark pairs are not very abundant in the very early phase after the collision [53]. In Ref.…”

Section: Photon Rate At Nontrivial Quark Fugacitiesmentioning

confidence: 99%

Nonequilibrium photon production in partonic transport simulations

et al. 2017

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“…Note that the linear λ -dependence of P and ε is a characteristic feature of the ideal gas of massless gluons and (anti)quarks studied in Refs. [18,27].…”

Section: Formulation Of the Modelmentioning

confidence: 99%

“…Similarly to Refs. [18,27] we postulate that λ is an explicit function of the local proper time τ P which increases from λ = 0 at τ P = τ 0 to λ = 1 at τ P − τ 0 → ∞. The following simple parametrization is used:…”

Section: Formulation Of the Modelmentioning

confidence: 99%

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Hydrodynamic modeling of a pure-glue initial scenario in high-energy hadron and heavy-ion collisions

Vovchenko¹,

Niemi²,

Satarov³

et al. 2016

Proceedings of 54th International Winter Meeting on Nuclear Physics — PoS(BORMIO2016)

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Partonic matter produced in the early stage of ultrarelativistic nucleus-nucleus collisions is assumed to be composed mainly of gluons, and quarks and antiquarks are produced at later times. The comparable hydrodynamic simulations of heavy-ion collisions for (2+1)-flavor and YangMills equations of state performed within three different hydrodynamic codes are presented. Assuming slow equilibration of quarks, the spectra and elliptic flows of thermal dileptons and photons are calculated for central Pb+Pb collisions at the LHC energy of √ s NN = 2.76 TeV. It is shown that a suppression of quarks at early times leads to a significant reduction of the yield of the thermal dileptons, but only to a rather modest suppression of the p T -distribution of direct photons. It is demonstrated that an enhancement of photon and dilepton elliptic flows might serve as a promising signature of the pure-glue initial state. Calculations based on Bjorken hydrodynamics suggest that collisions of small systems at intermediate energies available at RHIC or future FAIR facilities, may show stronger effects associated with initial pure gluodynamic evolution.

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Novel Physics Opportunities at the HESR-Collider with PANDA at FAIR

Frankfurt

Strikman

Larionov

et al. 2020

FIAS Interdisciplinary Science Series

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Exciting new scientific opportunities are presented for the PANDA detector at the High Energy Storage Ring in the redefinedpp(A) collider mode, HESR-C, at the Facility for Antiproton and Ion Research (FAIR) in Europe. The high luminosity, L ∼ 10 31 cm −2 s −1 , and a wide range of intermediate and high energies, √ s NN up to 30 GeV for pp(A) collisions will allow to explore a wide range of exciting topics in QCD, including the study of the production of excited open charm and arXiv:1908.02346v1 [nucl-th]

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Under‐saturation of quarks at early stages of relativistic nuclear collisions: The hot glue initial scenario and its observable signatures

Cited by 16 publications

References 42 publications

Nonequilibrium photon production in partonic transport simulations

Nonequilibrium photon production in partonic transport simulations

Hydrodynamic modeling of a pure-glue initial scenario in high-energy hadron and heavy-ion collisions

Novel Physics Opportunities at the HESR-Collider with PANDA at FAIR

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