Found 410 results, showing the newest relevant preprints. Sort by relevancy only.Update me on new preprints

Scaling properties of direct photons from gluon satur**ation** in **heavy** **ion** **collisions**

A recent analysis from the PHENIX collaboration on direct photon production has shown a universal, within experimental uncertainties, $multiplicity$ scaling, in which photon $p_{T}$-spectra for transverse momenta up to 2 GeV/$c$ are scaled with charged hadron pseudorapidity density at midrapidity raised to power $\alpha=1.25$. Expand abstract.

A recent analysis from the PHENIX collaboration on direct photon production has shown a universal, within experimental uncertainties, $multiplicity$ scaling, in which photon $p_{T}$-spectra for transverse momenta up to 2 GeV/$c$ are scaled with charged hadron pseudorapidity density at midrapidity raised to power $\alpha=1.25$. On the other hand particle production in hadron and nucleus collisions, photons included, exhibits $geometrical$ scaling in the similar $p_{T}$ range. The geometrical scaling follows from gluon saturation and

**collision**geometry. We show that these two scaling laws are interconnected and discuss physical conditions needed to relate one to another.192 days ago

10/10 relevant

arXiv

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arXiv

Constraints from the GW170817 merger event on the nuclear matter equ**ation** of state

In this paper we compare in particular the pressure-density rel

**ation**obtain**ed**from**heavy**-**ion****collisions**with the analysis of the NS merger event. Expand abstract.The detection of the GW170817 neutron star merger event has incited an intense research activity towards the understanding of the nuclear matter equation of state. In this paper we compare in particular the pressure-density relation obtained from

**heavy**-**ion****collisions**with the analysis of the NS merger event. Moreover, we present recent calculations of neutron star's moment of inertia and tidal deformability using various microscopic equations of state for nuclear and hybrid star configurations, and confirm several universal relations. We also discuss the recent constraints for the NS radii determined by GW170817, and find compatible radii between 12 and 13 kilometers, thus identifying the suitable equations of state.193 days ago

6/10 relevant

arXiv

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arXiv

Statist**ical** method in quark combin**ation** model

Taking a naive case of quark number fluctuat

**ions**and correlations at hadronization, we calculate ratios of multiplicity cumulants of final-state net-protons and discuss the potent**ial**applicability of quark combin**ation**model in studying hadron**ic**multiplicity fluctuations and the underlying... Expand abstract. We present a new method of solving the probability distribution for baryons, antibaryons and mesons at the hadronization of constituent quark and antiquark system. The hadronization is governed by the quark combination rule in the quark combination model developed by the Shandong Group. We use the method of the generating function to derive the outcome of the quark combination rule, which is much simpler and easier to be generalized than the original method. Furthermore, we use the formula of the quark combination rule and its generalization to study the property of multiplicity distribution of net-protons. Taking a naive case of quark number fluctuations and correlations at hadronization, we calculate ratios of multiplicity cumulants of final-state net-protons and discuss the potential applicability of quark combination model in studying hadronic multiplicity fluctuations and the underlying phase transition property in relativistic

**heavy**-**ion****collisions**.197 days ago

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arXiv

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arXiv

1+1 dimension**al** relativist**ic** magnetohydrodynamics with longitudinal
acceleration

Non-central heavy-ion collisions generate the strongest magnetic field of the order of $10^{18}-10^{19}$ Gauss due to the electric current produced by the positively charged spectators that travel at nearly the speed of light. Expand abstract.

Non-central

**heavy**-**ion****collisions**generate the strongest magnetic field of the order of $10^{18}-10^{19}$ Gauss due to the electric current produced by the positively charged spectators that travel at nearly the speed of light. Such transient electromagnetic fields may induce various novel effects in the hydrodynamic description of the quark gluon plasma for non-central**heavy**-**ion****collisions**. We investigate the longitudinal acceleration effects on the 1+1 dimensional relativistic magnetohydrodynamics with transverse magnetic fields. We analyze the proper time evolution of the system energy density. We find that the longitudinal acceleration parameter $\lambda^*$, magnetic field decay parameter $a$, equation of state $\kappa$, and initial magnetization $\sigma_0$ have nontrivial effects on the evolutions of the system energy density and temperature.199 days ago

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arXiv

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arXiv

Analysis on hadron spectra in **heavy**-**ion** **collisions** with a new
non-extensive approach

The transverse momentum spectra of identified charged hadrons stemming from high energy collisions at different beam energies are described by a new non-extensive distribution, the Kaniadakis $\kappa$-distribution, with respect to the constraints in non-extensive quantum statistics. Expand abstract.

The transverse momentum spectra of identified charged hadrons stemming from high energy

**collisions**at different beam energies are described by a new non-extensive distribution, the Kaniadakis $\kappa$-distribution, with respect to the constraints in non-extensive quantum statistics. All fittings are also compared with the Tsallis distributions as well as the usual Boltzmann-Gibbs one. $\chi^2/ndf$ is also used to test the fitting goodness of all functions. Our results show that these different non-extensive approaches can be well applied in high energy**collisions**rather than the classical one. The Kaniadakis statistics is typically better applied into such systems with both positive and negative particles considered. This provides an alternative non-extensive view to study high energy physics. Analysis on the fitting parameters are present as well. The similar relationships of all functions remind us of the further understanding of the non-extensivity.199 days ago

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arXiv

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arXiv

An insight into strangeness with $\phi$(1020) product**ion** in small to large **collision** systems with **AL**ICE at the LHC

Hadronic resonances are unique tools to investigate the interplay of re-scattering and regeneration effects in the hadronic phase of heavy-ion collisions. Expand abstract.

Hadronic resonances are unique tools to investigate the interplay of re-scattering and regeneration effects in the hadronic phase of

**heavy**-**ion****collisions**. As the $\phi$ meson has a longer lifetime compared to other resonances, it is expected that its production will not be affected by regeneration and re-scattering processes. Measurements in small**collision**systems such as proton-proton (pp)**collisions**provide a necessary baseline for**heavy**-**ion**data and help to tune pQCD inspired event generators. Given that the $\phi$ is a bound state of strange-antistrange quark pair (s$\bar{\rm{s}}$), measurements of its production can contribute to the study of strangeness production. Recent results obtained by using the ALICE detector show that although $\phi$ has zero net strangeness content, it behaves like a particle with open strangeness in small**collision**systems and the experimental results agree with thermal model predictions in large systems. The production mechanism of $\phi$ is yet to be understood. We report on measurements with the ALICE detector at the LHC of $\phi$ meson production in pp, p--Pb, Xe--Xe and Pb--Pb**collisions**. These results are reported for minimum bias event samples and as a function of the charged particle multiplicity or centrality. The results include the transverse momentum ($p_{\rm T}$) distributions of $\phi$ as well as the $\langle p_{\rm T}\rangle$ and particle yield ratios. The $\phi$ effective strangeness will be discussed in relation to descriptions of its production mechanism, such as strangeness canonical suppression, non-equilibrium production of strange quarks and thermal models.200 days ago

9/10 relevant

arXiv

9/10 relevant

arXiv

**Heavy** **ion** anisotropies: a closer look at the angular power spectrum

Anisotropies in the final state of heavy-ion collisions carry information on the creation, expansion and evolution of the quark-gluon plasma. Expand abstract.

Anisotropies in the final state of

**heavy**-**ion****collisions**carry information on the creation, expansion and evolution of the quark-gluon plasma. Currently, there is an abundance of studies on azimuthal anisotropies in comparison to longitudinal ones. The purpose of this work is to quantify angular $(\theta, \phi)$ correlations to further the understanding of the full spatial 3-D picture of emitted hadrons. Therefore, public ALICE data from Run 1 (2010) of Pb-Pb**collisions**at $\sqrt{s_{NN}} = 2.76\mathrm{~TeV}$ is analyzed through the estimation of an angular power spectrum. Issues with $|\eta| < 0.9$ limitation are tackled, as well as event multiplicity and detector efficiency. Firstly, spectra are calculated for toy Monte Carlo samples. Secondly,**heavy**-**ion**data spectra are presented for the full momentum phase space $0.15 < p_T < 100\mathrm{~GeV}$ and also separate intervals $p_T < 0.54\mathrm{~GeV}$ and $p_T > 0.54\mathrm{~GeV}$. The latter reveal how different geometries dominate at distinct scales and transverse momentum. Finally, the study submits particles generated through the AMPT model to the same power spectrum analysis. This comparison shows that in scales dominated by flow geometry, AMPT qualitatively describes the data spectra, while the opposite is true for smaller scales.200 days ago

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arXiv

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arXiv

Kinet**ic** approach to a relativistic BEC with inelastic processes

The phenomenon of Bose-Einstein condensation is investigated in the context of the Color-Glass-Condensate description of the initial state of ultrarelativistic heavy-ion collisions. Expand abstract.

The phenomenon of Bose-Einstein condensation is investigated in the context of the Color-Glass-Condensate description of the initial state of ultrarelativistic

**heavy**-**ion****collisions**. For the first time, in this paper we study the influence of particle-number changing $2 \leftrightarrow 3$ processes on the transient formation of a Bose-Einstein Condensate within an isotropic system of scalar bosons by including $2 \leftrightarrow 3$ interactions of massive bosons with constant and isotropic cross sections, following a Boltzmann equation. The one-particle distribution function is decomposed in a condensate part and a non-zero momentum part of excited modes, leading to coupled integro-differential equations for the time evolution of the condensate and phase-space distribution function, which are then solved numerically. Our simulations converge to the expected equilibrium state, and only for $\sigma_{23}/\sigma_{22} \ll 1$ we find that a Bose-Einstein condensate emerges and decays within a finite lifetime in contrast to the case where only binary scattering processes are taken into account, and the condensate is stable due to particle-number conservation. Our calculations demonstrate that Bose-Einstein Condensates in the very early stage of**heavy**-**ion****collisions**are highly unlikely, if inelastic**collisions**are significantly participating in the dynamical gluonic evolution.201 days ago

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arXiv

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arXiv

30 years of jet quenching

In the last 30 years, the physics of jet quenching has gone from an early stage of a pure theoret

**ical**idea to init**ial**theoretic**al**calculations, experimental verific**ation**and now a powerful diagnost**ic**tool for studying properties of the quark-gluon plasma (QGP) in high-energy... Expand abstract.In the last 30 years, the physics of jet quenching has gone from an early stage of a pure theoretical idea to initial theoretical calculations, experimental verification and now a powerful diagnostic tool for studying properties of the quark-gluon plasma (QGP) in high-energy

**heavy**-**ion****collisions**. I will describe my collaboration with Miklos Gyulassy in this exciting area of high-energy nuclear physics in the past 30 years on this special occasion of his 70th birthday and discuss what is ahead of us in jet tomographic study of QGP in**heavy**-**ion****collisions**.201 days ago

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arXiv

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arXiv

Experiment**al** searches for the chiral magnet**ic** effect in **heavy**-**ion** **collisions**

The chiral magnetic effect (CME) in quantum chromodynamics (QCD) refers to a charge separation (an electric current) of chirality imbalanced quarks generated along an external strong magnetic field. Expand abstract.

The chiral magnetic effect (CME) in quantum chromodynamics (QCD) refers to a charge separation (an electric current) of chirality imbalanced quarks generated along an external strong magnetic field. The chirality imbalance results from interactions of quarks, under the approximate chiral symmetry restoration, with metastable local domains of gluon fields of non-zero topological charges out of QCD vacuum fluctuations. Those local domains violate the $\mathcal{P}$ and $\mathcal{CP}$ invariance, potentially offering a solution to the strong $\mathcal{CP}$ problem in explaining the magnitude of the matter-antimatter asymmetry in today's universe. Relativistic

**heavy**-**ion**collisions, with the likely creation of the high energy density quark-gluon plasma and restoration of the approximate chiral symmetry, and the possibly long-lived strong magnetic field, provide a unique opportunity to detect the CME. Early measurements of the CME-induced charge separation in**heavy**-**ion****collisions**are dominated by physics backgrounds. Major efforts have been devoted to eliminate or reduce those backgrounds. We review those efforts, with a somewhat historical perspective, and focus on the recent innovative experimental undertakings in the search for the CME in**heavy**-**ion****collisions**.204 days ago

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arXiv

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arXiv