scholarly journals Strangeness production in high-energy collisions and Hawking–Unruh radiation

2017 ◽  
Vol 26 (03) ◽  
pp. 1750001 ◽  
Author(s):  
Abdel Nasser Tawfik ◽  
Hayam Yassin ◽  
Eman R. Abo Elyazeed
Keyword(s):  
Black Hole ◽  
Particle Production ◽  
Chemical Potential ◽  
Average Energy ◽  
High Energy ◽  
Strangeness Production ◽  
Linear Sigma Model ◽  
Quark Masses ◽  
Chemical Potentials ◽  
Particle Ratios

The assumption that the production of quark–antiquark pairs and their sequential string-breaking takes place, likely as a tunneling process, through the event horizon of the color confinement determines the freezeout temperature and gives a plausible interpretation for the thermal pattern of elementary and nucleus–nucleus collisions. When relating the black-hole electric charges to the baryon-chemical potentials, it was found that the phenomenologically deduced parameters from the ratios of various particle species and the higher-order moments of net-proton multiplicity in the statistical thermal models and Polyakov linear-sigma model agree well with the ones determined from the thermal radiation from charged black hole. Accordingly, the resulting freezeout conditions, such as normalized entropy density [Formula: see text] and average energy per particle [Formula: see text][Formula: see text]GeV, are confirmed at finite chemical potentials as well. Furthermore, the problem of strangeness production in elementary collisions can be interpreted by thermal particle production from the Hawking–Unruh radiation. Consequently, the freezeout temperature depends on the quark masses. This leads to a deviation from full equilibrium and thus a suppression of the strangeness production in the elementary collisions. But in nucleus–nucleus collisions, an average temperature should be introduced in order to dilute the quark masses. This nearly removes the strangeness suppression. An extension to finite chemical potentials is introduced. The particle ratios of kaon-to-pion ([Formula: see text]), phi-to-kaon ([Formula: see text]) and antilambda-to-pion ([Formula: see text]) are determined from Hawking–Unruh radiation and compared with the thermal calculations and the measurements in different experiments. We conclude that these particle ratios can be reproduced, at least qualitatively, as Hawking–Unruh radiation at finite chemical potential. With increasing energy, both [Formula: see text] and [Formula: see text] keep their maximum values at low SPS energies. But the further energy decrease rapidly reduces both ratios. For [Formula: see text], there is an increase with increasing [Formula: see text], i.e., no saturation is to be observed.

scholarly journals Equilibrium statistical–thermal models in high-energy physics

2014 ◽  
Vol 29 (17) ◽  
pp. 1430021 ◽  
Author(s):  
Abdel Nasser Tawfik
Keyword(s):  
Lattice Qcd ◽  
Particle Production ◽  
Chemical Potential ◽  
Heavy Ion ◽  
High Energy ◽  
Linear Sigma Model ◽  
Particle Model ◽  
Heavy Ion Physics ◽  
Thermal Models ◽  
Freeze Out

We review some recent highlights from the applications of statistical–thermal models to different experimental measurements and lattice QCD thermodynamics that have been made during the last decade. We start with a short review of the historical milestones on the path of constructing statistical–thermal models for heavy-ion physics. We discovered that Heinz Koppe formulated in 1948, an almost complete recipe for the statistical–thermal models. In 1950, Enrico Fermi generalized this statistical approach, in which he started with a general cross-section formula and inserted into it, the simplifying assumptions about the matrix element of the interaction process that likely reflects many features of the high-energy reactions dominated by density in the phase space of final states. In 1964, Hagedorn systematically analyzed the high-energy phenomena using all tools of statistical physics and introduced the concept of limiting temperature based on the statistical bootstrap model. It turns to be quite often that many-particle systems can be studied with the help of statistical–thermal methods. The analysis of yield multiplicities in high-energy collisions gives an overwhelming evidence for the chemical equilibrium in the final state. The strange particles might be an exception, as they are suppressed at lower beam energies. However, their relative yields fulfill statistical equilibrium, as well. We review the equilibrium statistical–thermal models for particle production, fluctuations and collective flow in heavy-ion experiments. We also review their reproduction of the lattice QCD thermodynamics at vanishing and finite chemical potential. During the last decade, five conditions have been suggested to describe the universal behavior of the chemical freeze-out parameters. The higher order moments of multiplicity have been discussed. They offer deep insights about particle production and to critical fluctuations. Therefore, we use them to describe the freeze-out parameters and suggest the location of the QCD critical endpoint. Various extensions have been proposed in order to take into consideration the possible deviations of the ideal hadron gas. We highlight various types of interactions, dissipative properties and location-dependences (spatial rapidity). Furthermore, we review three models combining hadronic with partonic phases; quasi-particle model, linear sigma model with Polyakov potentials and compressible bag model.

scholarly journals Energy Dependence of Particle Ratios in High Energy Nucleus-Nucleus Collisions: A USTFM Approach

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Inam-ul Bashir ◽  
Rameez Ahmad Parra ◽  
Hamid Nanda ◽  
Saeed Uddin
Keyword(s):  
Particle Production ◽  
Chemical Potential ◽  
Heavy Ion ◽  
High Energy ◽  
Ion Collisions ◽  
System A ◽  
Particle Ratios ◽  
High Degree ◽  
Chemical Freeze ◽  
Freeze Out

We study the identified particle ratios produced at mid-rapidity (y<0.5) in heavy-ion collisions, along with their correlations with the collision energy. We employ our earlier proposed unified statistical thermal freeze-out model (USTFM), which incorporates the effects of both longitudinal and transverse hydrodynamic flow in the hot hadronic system. A fair agreement seen between the experimental data and our model results confirms that the particle production in these collisions is of statistical nature. The variation of the chemical freeze-out temperature and the baryon chemical potential with respect to collision energies is studied. The chemical freeze-out temperature is found to be almost constant beyond the RHIC energy and is found to be close to the QCD predicted phase-transition temperature suggesting that the chemical freeze-out occurs soon after the hadronization takes place. The vanishing value of chemical potential at LHC indicates very high degree of nuclear transparency in the collision.

scholarly journals More on complex Sachdev-Ye-Kitaev eternal wormholes

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Pengfei Zhang
Keyword(s):  
Black Hole ◽  
Ground State ◽  
Effective Action ◽  
Chemical Potential ◽  
Specific Charge ◽  
Zero Temperature ◽  
Small Coupling ◽  
Chemical Potentials ◽  
Quench Dynamics ◽  
Two Sides

Abstract In this work, we study a generalization of the coupled Sachdev-Ye-Kitaev (SYK) model with U(1) charge conservations. The model contains two copies of the complex SYK model at different chemical potentials, coupled by a direct hopping term. In the zero-temperature and small coupling limit with small averaged chemical potential, the ground state is an eternal wormhole connecting two sides, with a specific charge Q = 0, which is equivalent to a thermofield double state. We derive the conformal Green’s functions and determine corresponding IR parameters. At higher chemical potential, the system transit into the black hole phase. We further derive the Schwarzian effective action and study its quench dynamics. Finally, we compare numerical results with the analytical predictions.

scholarly journals Strangeness at high μB: Recent data from FOPI and HADES

2018 ◽  
Vol 171 ◽  
pp. 02001
Author(s):  
Yvonne Leifels
Keyword(s):  
Experimental Data ◽  
Cross Sections ◽  
Particle Production ◽  
Chemical Potential ◽  
Good Description ◽  
Branching Ratio ◽  
Heavy Ion ◽  
Nuclear Medium ◽  
Strangeness Production ◽  
Baryon Chemical Potential

Strangeness production in heavy-ion reactions at incident energies at or below the threshold in NN collisions gives access to the characteristics of bulk nuclear matter and the properties of strange particles inside the hot and dense nuclear medium, like potentials and interaction cross sections. At these energies strangeness is produced in multi-step processes potentially via excitation of intermediate heavy resonances. The amount of experimental data on strangeness production at these energies has increased substantially during the last years due to the FOPI and the HADES experiments at SIS18 at GSI. Experimental data on K+ and K0 production support the assumption that particles with an s quark feel a moderate repulsive potential in the nuclear medium. The situation is not that clear in the case of K-. Here, spectra and flow of K- mesons is influenced by the contribution of ø mesons which are decaying into K+K- pairs with a branching ratio of 48.9 %. Depending on incident energy upto 30 % of all K- mesons measured in heavyion collisions are originating from ø-decays. Strangeness production yields - except the yield of Ξ- are described by thermal hadronisation models. Experimental data not only measured for heavy-ion collisions but also in proton induced reactions are described with sets of temperature T and baryon chemical potential μb which are close to a universal freeze-out curve which is fitting also experimental data obtained at lower baryon chemical potential. Despite the good description of most particle production yields, the question how this is achieved is still not settled and should be the focus of further investigations.

scholarly journals Residues, modularity, and the Cardy limit of the 4d $$ \mathcal{N} $$ = 4 superconformal index

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Kevin Goldstein ◽  
Vishnu Jejjala ◽  
Yang Lei ◽  
Sam van Leuven ◽  
Wei Li
Keyword(s):  
Black Hole ◽  
Chemical Potential ◽  
Specific Region ◽  
Partition Functions ◽  
Potential Space ◽  
Leading Order ◽  
Yang Mills ◽  
Superconformal Index ◽  
Chemical Potentials ◽  
Entropy Functions

Abstract We compute the superconformal index of the $$ \mathcal{N} $$ N = 4 SU(N) Yang-Mills theory through a residue calculation. The method is similar in spirit to the Bethe Ansatz formalism, except that all poles are explicitly known, and we do not require specialization of any of the chemical potentials. Our expression for the index allows us to revisit the Cardy limit using modular properties of four-dimensional supersymmetric partition functions. We find that all residues contribute at leading order in the Cardy limit. In a specific region of flavour chemical potential space, close to the two unrefined points, in fact all residues contribute universally. These universal residues precisely agree with the entropy functions of the asymptotically AdS5 black hole and its “twin saddle” respectively. Finally, we discuss how our formula is suited to study the implications of four-dimensional modularity for the index beyond the Cardy limit.

scholarly journals Possible interrelations among chemical freeze-out conditions

2016 ◽  
Vol 25 (03) ◽  
pp. 1650018 ◽  
Author(s):  
A. Tawfik ◽  
M. Y. El-Bakry ◽  
D. M. Habashy ◽  
M. T. Mohamed ◽  
E. Abbas
Keyword(s):  
Physical Meaning ◽  
Thermal Equilibrium ◽  
Chemical Potential ◽  
High Energy ◽  
Baryon Chemical Potential ◽  
Particle Ratios ◽  
Hadron Mass ◽  
Low Energies ◽  
Chemical Freeze ◽  
Freeze Out

At thermal equilibrium, different chemical freeze-out conditions have been proposed so far. They have an ultimate aim of proposing a universal description for the chemical freeze-out parameters ([Formula: see text] and [Formula: see text]), which are to be extracted from the statistical fitting of different particle ratios measured at various collision energies with calculations from thermal models. A systematic comparison between these conditions is presented. The physical meaning of each of them and their sensitivity to the hadron mass cuts are discussed. Based on availability, some of them are compared with recent lattice calculations. We found that most of these conditions are thermodynamically equivalent, especially at small baryon chemical potential. We propose that further crucial consistency tests should be performed at low energies. The fireball thermodynamics is another way of guessing conditions describing the chemical freeze-out parameters extracted from high-energy experiments. We endorse the possibility that the various chemical freeze-out conditions should be interpreted as different aspects of one universal condition.

scholarly journals Hadron freeze-out and Unruh radiation

2015 ◽  
Vol 24 (07) ◽  
pp. 1550056 ◽  
Author(s):  
Paolo Castorina ◽  
Alfredo Iorio ◽  
Helmut Satz
Keyword(s):  
Chemical Potential ◽  
Average Energy ◽  
String Tension ◽  
High Energy ◽  
Hadron Production ◽  
Entropy Density ◽  
Baryon Chemical Potential ◽  
High Energy Collisions ◽  
Production Pattern ◽  
Freeze Out

In this paper, we consider hadron production in high energy collisions as an Unruh radiation phenomenon. This mechanism describes the production pattern of newly formed hadrons and is directly applicable at vanishing baryon chemical potential, μ ≃ 0. It had already been found to correctly yield the hadronization temperature, [Formula: see text] in terms of the string tension σ. Here, we show that the Unruh mechanism also predicts hadronic freeze-out conditions, giving [Formula: see text] in terms of the entropy density s and [Formula: see text] for the average energy per hadron. These predictions provide a theoretical basis for previous phenomenological results and are also in accord with recent lattice studies.

scholarly journals QCD at finite isospin chemical potential

2018 ◽  
Vol 175 ◽  
pp. 07020 ◽  
Author(s):  
Bastian B. Brandt ◽  
Gergely Endrődi ◽  
Sebastian Schmalzbauer
Keyword(s):  
Taylor Expansion ◽  
Chemical Potential ◽  
Quark Masses ◽  
Monte Carlo Techniques ◽  
Chemical Potentials ◽  
Cosmological Application ◽  
Sign Problem ◽  
Charged Pions ◽  
First Results

We investigate the properties of QCD at finite isospin chemical potential at zero and non-zero temperatures. This theory is not affected by the sign problem and can be simulated using Monte-Carlo techniques. With increasing isospin chemical potential and temperatures below the deconfinement transition the system changes into a phase where charged pions condense, accompanied by an accumulation of low modes of the Dirac operator. The simulations are enabled by the introduction of a pionic source into the action, acting as an infrared regulator for the theory, and physical results are obtained by removing the regulator via an extrapolation. We present an update of our study concerning the associated phase diagram using 2+1 flavours of staggered fermions with physical quark masses and the comparison to Taylor expansion. We also present first results for our determination of the equation of state at finite isospin chemical potential and give an example for a cosmological application. The results can also be used to gain information about QCD at small baryon chemical potentials using reweighting with respect to the pionic source parameter and the chemical potential and we present first steps in this direction.

scholarly journals The scalar chemical potential in cosmological collider physics

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Arushi Bodas ◽  
Soubhik Kumar ◽  
Raman Sundrum
Keyword(s):  
Particle Production ◽  
Chemical Potential ◽  
Direct Detection ◽  
Heavy Particle ◽  
Scalar Particle ◽  
Energy Scale ◽  
Fine Tuning ◽  
Tree Level ◽  
Heavy Particles ◽  
Non Gaussian

Abstract Non-analyticity in co-moving momenta within the non-Gaussian bispectrum is a distinctive sign of on-shell particle production during inflation, presenting a unique opportunity for the “direct detection” of particles with masses as large as the inflationary Hubble scale (H). However, the strength of such non-analyticity ordinarily drops exponentially by a Boltzmann-like factor as masses exceed H. In this paper, we study an exception provided by a dimension-5 derivative coupling of the inflaton to heavy-particle currents, applying it specifically to the case of two real scalars. The operator has a “chemical potential” form, which harnesses the large kinetic energy scale of the inflaton, $$ {\overset{\cdot }{\phi}}_0^{1/2}\approx 60H $$ ϕ ⋅ 0 1 / 2 ≈ 60 H , to act as an efficient source of scalar particle production. Derivative couplings of inflaton ensure radiative stability of the slow-roll potential, which in turn maintains (approximate) scale-invariance of the inflationary correlations. We show that a signal not suffering Boltzmann suppression can be obtained in the bispectrum with strength fNL ∼ $$ \mathcal{O} $$ O (0.01–10) for an extended range of scalar masses $$ \lesssim {\overset{\cdot }{\phi}}_0^{1/2} $$ ≲ ϕ ⋅ 0 1 / 2 , potentially as high as 1015 GeV, within the sensitivity of upcoming LSS and more futuristic 21-cm experiments. The mechanism does not invoke any particular fine-tuning of parameters or breakdown of perturbation-theoretic control. The leading contribution appears at tree-level, which makes the calculation analytically tractable and removes the loop-suppression as compared to earlier chemical potential studies of non-zero spins. The steady particle production allows us to infer the effective mass of the heavy particles and the chemical potential from the variation in bispectrum oscillations as a function of co-moving momenta. Our analysis sets the stage for generalization to heavy bosons with non-zero spin.

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