Research

17 pages, 1612 KiB

Open AccessArticle

The Formulation of Scaling Expansion in an Euler-Poisson Dark-Fluid Model

by Balázs Endre Szigeti, Imre Ferenc Barna and Gergely Gábor Barnaföldi

Universe 2023, 9(10), 431; https://doi.org/10.3390/universe9100431 - 27 Sep 2023

Viewed by 923

We present a dark fluid model described as a non-viscous, non-relativistic, rotating, and self-gravitating fluid. We assume that the system has spherical symmetry and that the matter can be described by the polytropic equation of state. The induced coupled nonlinear partial differential system [...] Read more.

We present a dark fluid model described as a non-viscous, non-relativistic, rotating, and self-gravitating fluid. We assume that the system has spherical symmetry and that the matter can be described by the polytropic equation of state. The induced coupled nonlinear partial differential system of equations was solved using a self-similar time-dependent ansatz introduced by L. Sedov and G.I. Taylor. These kinds of solutions were successfully used to describe blast waves induced by an explosion following the Guderley–Landau–Stanyukovich problem. We show that the result of our quasi-analytic solutions are fully consistent with the Newtonian cosmological framework. We analyzed relevant quantities from the model, namely, the evolution of the Hubble parameter and the density parameter ratio, finding that our solutions can be applied to describe normal-to-dark energy on the cosmological scale. Full article

(This article belongs to the Special Issue Zimányi School – Heavy Ion Physics)

► Show Figures

Figure 1

12 pages, 1127 KiB

Open AccessArticle

Collisional Broadening within a Hadronic Transport Approach

by Branislav Balinovic, Renan Hirayama and Hannah Elfner

Universe 2023, 9(9), 414; https://doi.org/10.3390/universe9090414 - 09 Sep 2023

Viewed by 830

Abstract

We explore the emergence of the collisional broadening of hadrons under the influence of different media using the hadronic transport approach SMASH (Simulating Many Accelerated Strongly interacting Hadrons), which employs vacuum properties and contains no a priori information about in-medium effects. In this [...] Read more.

We explore the emergence of the collisional broadening of hadrons under the influence of different media using the hadronic transport approach SMASH (Simulating Many Accelerated Strongly interacting Hadrons), which employs vacuum properties and contains no a priori information about in-medium effects. In this context, we define collisional broadening as a decrease in the lifetime of hadrons, and it arises from an interplay between the cross-sections for inelastic processes and the available phase space. We quantify this effect for various hadron species, in both a thermal gas in equilibrium and in nuclear collisions. Furthermore, we distinguish the individual contribution of each process and verify the medium response to different vacuum assumptions; we see that the decay width that depends on the resonance mass leads to a larger broadening than a mass-independent scenario. Full article

(This article belongs to the Special Issue Zimányi School – Heavy Ion Physics)

► Show Figures

Figure 1

25 pages, 7759 KiB

Open AccessArticle

Phase Transitions in the Interacting Relativistic Boson Systems

by Dmitry Anchishkin, Volodymyr Gnatovskyy, Denys Zhuravel, Vladyslav Karpenko, Igor Mishustin and Horst Stoecker

Universe 2023, 9(9), 411; https://doi.org/10.3390/universe9090411 - 07 Sep 2023

Cited by 2 | Viewed by 942

Abstract

The thermodynamic properties of the interacting particle–antiparticle boson system at high temperatures and densities were investigated within the framework of scalar and thermodynamic mean-field models. We assume isospin (charge) density conservation in the system. The equations of state and thermodynamic functions are determined [...] Read more.

The thermodynamic properties of the interacting particle–antiparticle boson system at high temperatures and densities were investigated within the framework of scalar and thermodynamic mean-field models. We assume isospin (charge) density conservation in the system. The equations of state and thermodynamic functions are determined after solving the self-consistent equations. We study the relationship between attractive and repulsive forces in the system and the influence of these interactions on the thermodynamic properties of the bosonic system, especially on the development of the Bose–Einstein condensate. It is shown that under “weak” attraction, the boson system has a phase transition of the second order, which occurs every time the dependence of the particle density crosses the critical curve or even touches it. It was found that with a “strong” attractive interaction, the system forms a Bose condensate during a phase transition of the first order, and, despite the finite value of the isospin density, these condensate states are characterized by a zero chemical potential. That is, such condensate states cannot be described by the grand canonical ensemble since the chemical potential is involved in the conditions of condensate formation, so it cannot be a free variable when the system is in the condensate phase. Full article

(This article belongs to the Special Issue Zimányi School – Heavy Ion Physics)

► Show Figures

Figure 1

13 pages, 355 KiB

Open AccessArticle

Lévy α-Stable Model for the Non-Exponential Low-|t| Proton–Proton Differential Cross-Section

by Tamás Csörgő, Sándor Hegyi and István Szanyi

Universe 2023, 9(8), 361; https://doi.org/10.3390/universe9080361 - 03 Aug 2023

Cited by 1 | Viewed by 716

Abstract

It is known that the Real Extended Bialas–Bzdak (ReBB) model describes the proton–proton (

p p

) and proton–antiproton (

p \bar{p}

) differential cross-section data in a statistically non-excludible way, i.e., with a confidence level greater than or equal to 0.1% [...] Read more.

It is known that the Real Extended Bialas–Bzdak (ReBB) model describes the proton–proton (

p p

) and proton–antiproton (

p \bar{p}

) differential cross-section data in a statistically non-excludible way, i.e., with a confidence level greater than or equal to 0.1% in the center of mass energy range 546 GeV

\leq \sqrt{s} \leq 8

TeV and in the squared four-momentum transfer range 0.37 GeV² ≤ −t ≤ 1.2 GeV². Considering, instead of Gaussian, a more general Lévy

α

-stable shape for the parton distributions of the constituent quark and diquark inside the proton and for the relative separation between them, a generalized description of data is obtained, where the ReBB model corresponds to the

α = 2

special case. Extending the model to

α < 2

, we conjecture that the validity of the model can be extended to a wider kinematic range, in particular, to lower values of the four-momentum transfer

- t

. We present the formal Lévy

α

-stable generalization of the Bialas–Bzdak model and show that a simplified version of this model can be successfully fitted, with

α < 2

, to the non-exponential, low

- t

differential cross-section data of elastic proton–proton scattering at

\sqrt{s} = 8

TeV. Full article

(This article belongs to the Special Issue Zimányi School – Heavy Ion Physics)

► Show Figures

Figure 1

16 pages, 613 KiB

Open AccessArticle

Synthesis of Elements in Compact Stars in Pycnonuclear Reactions with Carbon Isotopes: Quasibound States vs. States of Zero-Points Vibrations

by Sergei P. Maydanyuk, Gyorgy Wolf and Kostiantyn A. Shaulsky

Universe 2023, 9(8), 354; https://doi.org/10.3390/universe9080354 - 29 Jul 2023

Cited by 1 | Viewed by 724

Abstract

(1) Purpose: Conditions of formation of compound nuclear systems needed for synthesis of heavy nuclei in pycnonuclear reactions in compact stars are studied on a quantum mechanical basis. (2) Methods: The method of multiple internal reflections is applied for pycnonuclear reactions in compact [...] Read more.

(1) Purpose: Conditions of formation of compound nuclear systems needed for synthesis of heavy nuclei in pycnonuclear reactions in compact stars are studied on a quantum mechanical basis. (2) Methods: The method of multiple internal reflections is applied for pycnonuclear reactions in compact stars with new calculations of quasibound spectra and spectra of zero-point vibrations. (3) Results: Peculiarities of the method are analyzed for reaction with isotopes of Carbon. The developed method takes into account continuity and conservation of quantum flux (describing pycnonuclear reaction) inside the full spacial region of reaction, including the nuclear region. This gives the appearance of new states (called quasibound states) in which compound nuclear systems of Magnesium are formed with the largest probability. These states have not been studied yet in synthesis of elements in stars. Energy spectra of zero-point vibrations and spectra of quasibound states are estimated with high precision for reactions with isotopes of Carbon. For the first time, the influence of plasma screening on quasibound states and states of zero-point vibrations in pycnonuclear reactions has been studied. (4) Conclusions: The probability of formation of a compound nucleus in quasibound states in pycnonuclear reaction is essentially larger than the probability of formation of this system in states of zero-point vibrations studied by Zel’dovich and followers. Therefore, synthesis of Magnesium from isotopes of Carbon is more probable through the quasibound states than through the states of zero-point vibrations in compact stars. Energy spectra of zero-point vibrations are changed essentially after taking plasma screening into account. Analysis shows that from all studied isotopes of Magnesium, only ²⁴Mg is stable after synthesis at an energy of relative motion of 4.881 MeV of the incident nuclei ¹²C. Full article

(This article belongs to the Special Issue Zimányi School – Heavy Ion Physics)

► Show Figures

Figure 1

12 pages, 1524 KiB

Open AccessCommunication

Charged Kaon Femtoscopy with Lévy Sources in

\sqrt{s_{NN}}

= 200 GeV Au+Au Collisions at PHENIX

by László Kovács

Universe 2023, 9(7), 336; https://doi.org/10.3390/universe9070336 - 17 Jul 2023

Cited by 2 | Viewed by 752

Abstract

The PHENIX experiment measured two-particle Bose–Einstein quantum-statistical correlations of charged kaons in Au+Au collisions at

\sqrt{s_{NN}}

= 200 GeV. The correlation functions are parametrized assuming that the source emitting the particles has a Lévy shape, characterized by the Lévy exponent

α

and [...] Read more.

The PHENIX experiment measured two-particle Bose–Einstein quantum-statistical correlations of charged kaons in Au+Au collisions at

\sqrt{s_{NN}}

= 200 GeV. The correlation functions are parametrized assuming that the source emitting the particles has a Lévy shape, characterized by the Lévy exponent

α

and the Lévy scale R. By introducing the intercept parameter

λ

, we account for the core–halo fraction. The parameters are investigated as a function of transverse mass. The comparison of the parameters measured for kaon–kaon with those measured from pion–pion correlation may clarify the connection of Lévy parameters to physical processes. Full article

(This article belongs to the Special Issue Zimányi School – Heavy Ion Physics)

► Show Figures

Figure 1

12 pages, 6565 KiB

Open AccessCommunication

Charged Particle Pseudorapidity Distributions Measured with the STAR EPD

by Mátyás Molnár

Universe 2023, 9(7), 335; https://doi.org/10.3390/universe9070335 - 15 Jul 2023

Viewed by 903

Abstract

In 2018, in preparation for the Beam Energy Scan II, the STAR detector was upgraded with the Event Plane Detector (EPD). The instrument enhanced STAR’s capabilities in centrality determination for fluctuation measurements, event plane resolution for flow measurements, and in triggering overall. Due [...] Read more.

In 2018, in preparation for the Beam Energy Scan II, the STAR detector was upgraded with the Event Plane Detector (EPD). The instrument enhanced STAR’s capabilities in centrality determination for fluctuation measurements, event plane resolution for flow measurements, and in triggering overall. Due to its fine radial granularity, it can also be utilized to measure pseudorapidity distributions of the produced charged primary particles, in EPD’s pseudorapidity coverage of

2.15 < | η | < 5.09

. As such a measurement cannot be done directly, the response of the detector to the primary particles has to be understood well. The detector response matrix was determined via Monte Carlo simulations, and corrected charged particle pseudorapidity distributions were obtained in Au + Au collisions at the center of mass collision energies

\sqrt{s_{_{N N}}}

= 19.6 and 27.0 GeV using an iterative unfolding procedure. Several systematic checks of the method were also done. Full article

(This article belongs to the Special Issue Zimányi School – Heavy Ion Physics)

► Show Figures

Figure 1

11 pages, 533 KiB

Open AccessArticle

Coulomb Corrections for Bose–Einstein Correlations from One- and Three-Dimensional Lévy-Type Source Functions

by Bálint Kurgyis, Dániel Kincses, Márton Nagy and Máté Csanád

Universe 2023, 9(7), 328; https://doi.org/10.3390/universe9070328 - 10 Jul 2023

Cited by 13 | Viewed by 853

Abstract

In the study of femtoscopic correlations in high-energy physics, besides Bose–Einstein correlations, one has to take final-state interactions into account. Amongst them, Coulomb interactions play a prominent role in the case of charged particles. Recent measurements have shown that in heavy-ion collisions, Bose–Einstein [...] Read more.

In the study of femtoscopic correlations in high-energy physics, besides Bose–Einstein correlations, one has to take final-state interactions into account. Amongst them, Coulomb interactions play a prominent role in the case of charged particles. Recent measurements have shown that in heavy-ion collisions, Bose–Einstein correlations can be best described by Lévy-type sources instead of the more common Gaussian assumption. Furthermore, three-dimensional measurements have indicated that, depending on the choice of frame, a deviation from spherical symmetry observed under the assumption of Gaussian source functions persists in the case of Lévy-type sources. To clarify such three-dimensional Lévy-type correlation measurements, it is thus important to study the effect of Coulomb interactions in the case of non-spherical Lévy sources. We calculated the Coulomb correction factor numerically in the case of such a source function for assorted kinematic domains and parameter values using the Metropolis–Hastings algorithm and compared our results with previous methods to treat Coulomb interactions in the presence of Lévy sources. Full article

(This article belongs to the Special Issue Zimányi School – Heavy Ion Physics)

► Show Figures

Figure 1

14 pages, 840 KiB

Open AccessArticle

Measurements of J/ψ Production vs. Event Multiplicity in Forward Rapidity in p + p Collisions in the PHENIX Experiment

by Zhaozhong Shi

Universe 2023, 9(7), 322; https://doi.org/10.3390/universe9070322 - 04 Jul 2023

Viewed by 737

Abstract

J / ψ

, a charmonium bound state made of a charm and an anti-charm quark, was discovered in the 1970s and confirmed the quark model. Because the mass of charm quarks is significantly above the quantum chromodynamics (QCD) scale [...] Read more.

J / ψ

, a charmonium bound state made of a charm and an anti-charm quark, was discovered in the 1970s and confirmed the quark model. Because the mass of charm quarks is significantly above the quantum chromodynamics (QCD) scale

Λ_{Q C D}

, charmonia are considered excellent probes to test perturbative quantum chromodynamics (pQCD) calculations. In recent decades, they have been studied extensively at different high-energy colliders. However, their production mechanisms, which involve multiple scales, are still not very well understood. Recently, in high-multiplicity

p + p

collisions at RHIC and at the LHC, a significant enhancement of

J / ψ

production yield has been observed, which suggests a strong contribution of multi-parton interaction (MPI). This is different from the traditional pQCD picture, where charm quark pairs are produced from a single hard scattering between partons in

p + p

collisions. In this work, we will report the

J / ψ

normalized production yield as a function of normalized charged particle multiplicity over a board range of rapidity and event multiplicity in the

J / ψ \to μ^{+} μ^{-}

channel with PHENIX Run 15

p + p

data at

\sqrt{s} = 200

GeV. The results are compared with PYTHIA 8 simulations with the MPI option turned on and off. Finally, the outlooks of

J / ψ

in

p + A u

and

A u + p

collisions, along with color glass condensate (CGC) predictions and the multiplicity-dependent

ψ (2 S) / J / ψ

ratio in

p + p

data, will be briefly discussed. Full article

(This article belongs to the Special Issue Zimányi School – Heavy Ion Physics)

► Show Figures

Figure 1

14 pages, 673 KiB

Open AccessArticle

Centrality-Dependent Lévy HBT Analysis in

\sqrt{s_{_{NN}}} = 5.02

TeV PbPb Collisions at CMS

by Balázs Kórodi

Universe 2023, 9(7), 318; https://doi.org/10.3390/universe9070318 - 01 Jul 2023

Cited by 1 | Viewed by 787

Abstract

The measurement of two-particle Bose–Einstein momentum correlation functions are presented using

\sqrt{s_{_{NN}}} = 5.02

TeV PbPb collision data, recorded by the CMS experiment in 2018. The measured correlation functions are discussed in terms of Lévy-type source distributions. The Lévy source parameters are [...] Read more.

The measurement of two-particle Bose–Einstein momentum correlation functions are presented using

\sqrt{s_{_{NN}}} = 5.02

TeV PbPb collision data, recorded by the CMS experiment in 2018. The measured correlation functions are discussed in terms of Lévy-type source distributions. The Lévy source parameters are extracted as functions of transverse mass and collision centrality. These source parameters include the correlation strength

λ

, the Lévy stability index

α

, and the Lévy scale parameter R. The source shape, characterized by

α

, is found to be neither Gaussian nor Cauchy. A hydrodynamic-like scaling of R is also observed. Full article

(This article belongs to the Special Issue Zimányi School – Heavy Ion Physics)

► Show Figures

Figure 1

7 pages, 269 KiB

Open AccessCommunication

Event-Shape-Dependent Analysis of Charm–Anticharm Azimuthal Correlations in Simulations

by Anikó Horváth, Eszter Frajna and Róbert Vértesi

Universe 2023, 9(7), 308; https://doi.org/10.3390/universe9070308 - 27 Jun 2023

Cited by 2 | Viewed by 540

Abstract

In high-energy collisions of small systems, by high-enough final-state multiplicities, a collective behaviour is present that is similar to the flow patterns observed in heavy-ion collisions. Recent studies connect this collectivity to semi-soft vacuum-QCD processes. Here we explore QCD production mechanisms using angular [...] Read more.

In high-energy collisions of small systems, by high-enough final-state multiplicities, a collective behaviour is present that is similar to the flow patterns observed in heavy-ion collisions. Recent studies connect this collectivity to semi-soft vacuum-QCD processes. Here we explore QCD production mechanisms using angular correlations of heavy flavour using simulated proton-proton collisions at

\sqrt{s} = 13

TeV with the PYTHIA8 Monte Carlo event generator. We demonstrate that the event shape is strongly connected to the production mechanisms. Flattenicity, a novel event descriptor, can be used to separate events containing the final-state radiation from the rest of the events. Full article

(This article belongs to the Special Issue Zimányi School – Heavy Ion Physics)

► Show Figures

Figure 1

11 pages, 568 KiB

Open AccessCommunication

Kaon Femtoscopy with Lévy-Stable Sources from

\sqrt{s_{_{NN}}} = 200

GeV

Au + Au

Collisions at RHIC

by Ayon Mukherjee

Universe 2023, 9(7), 300; https://doi.org/10.3390/universe9070300 - 22 Jun 2023

Cited by 2 | Viewed by 724

Abstract

Femtoscopy has the capacity to probe the space-time geometry of the particle-emitting source in heavy-ion collisions. In particular, femtoscopy of like-sign kaon pairs may shed light on the origin of non-Gaussianity of the spatial emission probability density. The momentum correlations between like-sign kaon [...] Read more.

Femtoscopy has the capacity to probe the space-time geometry of the particle-emitting source in heavy-ion collisions. In particular, femtoscopy of like-sign kaon pairs may shed light on the origin of non-Gaussianity of the spatial emission probability density. The momentum correlations between like-sign kaon pairs are measured in data recorded by the STAR experiment, from

\sqrt{s_{_{NN}}} = 200

GeV

Au + Au

collisions at RHIC, BNL. Preliminary results hint at the possible existence of non-Gaussian, Lévy-stable sources, with the likely presence of an anomalous diffusion process in the signal for the identically charged kaon pairs so produced. More statistically significant studies at lower centre-of-mass energies may contribute to the search for the critical end point of QCD. Full article

(This article belongs to the Special Issue Zimányi School – Heavy Ion Physics)

► Show Figures

Figure 1

10 pages, 365 KiB

Open AccessCommunication

Femtoscopic Correlation Measurement with Symmetric Lévy-Type Source at NA61/SHINE

by Barnabás Pórfy

Universe 2023, 9(7), 298; https://doi.org/10.3390/universe9070298 - 21 Jun 2023

Cited by 6 | Viewed by 811

Abstract

Measuring quantum-statistical, femtoscopic (including final state interactions) momentum correlations with final state interactions in high-energy nucleus-nucleus collisions reveal the space-time structure of the particle-emitting source created. In this paper, we report NA61/SHINE measurements of femtoscopic correlations of identified pion pairs and describe said [...] Read more.

Measuring quantum-statistical, femtoscopic (including final state interactions) momentum correlations with final state interactions in high-energy nucleus-nucleus collisions reveal the space-time structure of the particle-emitting source created. In this paper, we report NA61/SHINE measurements of femtoscopic correlations of identified pion pairs and describe said correlations based on symmetric Lévy-type sources in Ar+Sc collisions at 150A GeV/c. We investigate the transverse mass dependence of the Lévy-type source parameters and discuss their possible interpretations. Full article

(This article belongs to the Special Issue Zimányi School – Heavy Ion Physics)

► Show Figures

Figure 1

16 pages, 605 KiB

Open AccessArticle

Even and Odd Self-Similar Solutions of the Diffusion Equation for Infinite Horizon

by László Mátyás and Imre Ferenc Barna

Universe 2023, 9(6), 264; https://doi.org/10.3390/universe9060264 - 31 May 2023

Cited by 1 | Viewed by 784

Abstract

In the description of transport phenomena, diffusion represents an important aspect. In certain cases, the diffusion may appear together with convection. In this paper, we study the diffusion equation with the self-similar Ansatz. With an appropriate change of variables, we have found an [...] Read more.

In the description of transport phenomena, diffusion represents an important aspect. In certain cases, the diffusion may appear together with convection. In this paper, we study the diffusion equation with the self-similar Ansatz. With an appropriate change of variables, we have found an original new type of solution of the diffusion equation for infinite horizon. We derive novel even solutions of diffusion equation for the boundary conditions presented. For completeness, the odd solutions are also mentioned as well, as part of the previous works. We have found a countable set of even and odd solutions, of which linear combinations also fulfill the diffusion equation. Finally, the diffusion equation with a constant source term is discussed, which also has even and odd solutions. Full article

(This article belongs to the Special Issue Zimányi School – Heavy Ion Physics)

► Show Figures

Figure 1

6 pages, 1450 KiB

Open AccessCommunication

With Nanoplasmonics towards Fusion

by Tamás Sándor Biró, Norbert Kroó, László Pál Csernai, Miklós Veres, Márk Aladi, István Papp, Miklós Ákos Kedves, Judit Kámán, Ágnes Nagyné Szokol, Roman Holomb, István Rigó, Attila Bonyár, Alexandra Borók, Shireen Zangana, Rebeka Kovács, Nóra Tarpataki, Mária Csete, András Szenes, Dávid Vass, Emese Tóth, Gábor Galbács and Melinda Szalóki Show full author list Hide full author list

Universe 2023, 9(5), 233; https://doi.org/10.3390/universe9050233 - 17 May 2023

Cited by 1 | Viewed by 1045

Abstract

A status report is presented about the Nanoplasmonic Laser Induced Fusion Experiment (NAPLIFE). The goal is to investigate and verify plasmonically enhanced phenomena on the surfaces of nanoantennas embedded in a polymer target at laser intensities up to a few times

10^{16}

[...] Read more.

A status report is presented about the Nanoplasmonic Laser Induced Fusion Experiment (NAPLIFE). The goal is to investigate and verify plasmonically enhanced phenomena on the surfaces of nanoantennas embedded in a polymer target at laser intensities up to a few times

10^{16}

W/cm

^{2}

and pulse durations of 40–120 fs. The first results on enhanced crater formation for Au-doped polymer targets are shown, and SERS signals typical for

{CD}_{2}

and

ND

bound vibrations are cited. Trials to detect

D / H

ratio by means of LIBS measurments are reported. Plasmonics has the potential to work at these intensities, enhancing the energy and deuterium production, due to thus far unknown mechanisms. Full article

(This article belongs to the Special Issue Zimányi School – Heavy Ion Physics)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Zimányi School – Heavy Ion Physics

Share This Special Issue

Special Issue Editors

Special Issue Information

Published Papers (15 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI