Theoretical analysis of pT spectra of light-flavor hadrons in p + p collisions at s = 7 TeV under differential and single freeze-out scenarios

2021 ◽  
pp. 2150160
Author(s):  
Pramod Kumar ◽  
P. K. Khandai ◽  
Kapil Saraswat ◽  
V. Singh
Keyword(s):  
Charged Particle ◽  
Theoretical Analysis ◽  
Thermal Equilibrium ◽  
Published Data ◽  
Rapidity Region ◽  
Massive Particles ◽  
Tsallis Distribution ◽  
Freeze Out ◽  
Charged Particle Multiplicities

We present the published data of ALICE at mid-rapidity region ([Formula: see text]) to study the [Formula: see text] spectra of light-flavor hadrons in different charged-particle multiplicities ([Formula: see text]) for [Formula: see text] collisions at [Formula: see text] TeV. We parametrize the [Formula: see text] spectra of different hadrons such as pion ([Formula: see text]), kaon ([Formula: see text]), [Formula: see text], [Formula: see text] ([Formula: see text]), [Formula: see text], proton ([Formula: see text]), lambda ([Formula: see text]), cascade ([Formula: see text]) and omega ([Formula: see text]) using Tsallis distribution. We perform this analysis by considering both differential and single freeze-out scenarios. In the differential freeze-out scenario, both the Tsallis parameters [Formula: see text] and [Formula: see text] increase with charged multiplicities for most of the particles. This implies that the multipartonic interactions increase the multiplicities in [Formula: see text] collisions and it brings the system towards thermal equilibrium. Here we observe that both [Formula: see text] and [Formula: see text] have different trends with different masses of particles. The parameters [Formula: see text] and [Formula: see text] are higher for massive particles (except for multistrange baryons) in comparison to lighter ones, which supports the differential freeze-out scenario and suggests that massive particles freeze-out earlier from the system. In the case of single freeze-out scenario, the value of parameter [Formula: see text] has a little variation with multiplicity and the parameter [Formula: see text] increases with multiplicity. This implies that the degree of thermalization remains similar for the events of different multiplicity classes.

scholarly journals The dawn of FIMP Dark Matter: A review of models and constraints

2017 ◽  
Vol 32 (27) ◽  
pp. 1730023 ◽  
Author(s):  
Nicolás Bernal ◽  
Matti Heikinheimo ◽  
Tommi Tenkanen ◽  
Kimmo Tuominen ◽  
Ville Vaskonen
Keyword(s):  
Dark Matter ◽  
Early Universe ◽  
Thermal Equilibrium ◽  
Model Building ◽  
Massive Particles ◽  
Visible Sector ◽  
Freeze Out

We present an overview of scenarios where the observed Dark Matter (DM) abundance consists of Feebly Interacting Massive Particles (FIMPs), produced nonthermally by the so-called freeze-in mechanism. In contrast to the usual freeze-out scenario, frozen-in FIMP DM interacts very weakly with the particles in the visible sector and never attained thermal equilibrium with the baryon–photon fluid in the early Universe. Instead of being determined by its annihilation strength, the DM abundance depends on the decay and annihilation strengths of particles in equilibrium with the baryon–photon fluid, as well as couplings in the DM sector. This makes frozen-in DM very difficult but not impossible to test. In this review, we present the freeze-in mechanism and its variations considered in the literature (dark freeze-out and reannihilation), compare them to the standard DM freeze-out scenario, discuss several aspects of model building, and pay particular attention to observational properties and general testability of such feebly interacting DM.

scholarly journals Charged-particle multiplicities in charged-current neutrino– and anti-neutrino–nucleus interactions

2007 ◽  
Vol 51 (4) ◽  
Author(s):  
A. Kayis-Topaksu ◽  
◽  
G. Önengüt ◽  
R. van Dantzig ◽  
M. de Jong ◽  
...  
Keyword(s):  
Charged Particle ◽  
Charged Current ◽  
Charged Particle Multiplicities

Light charged particle multiplicities in fusion and quasifission reactions

2018 ◽  
Vol 54 (1) ◽  
Author(s):  
Sh. A. Kalandarov ◽  
G. G. Adamian ◽  
N. V. Antonenko ◽  
D. Lacroix ◽  
J. P. Wieleczko
Keyword(s):  
Charged Particle ◽  
Light Charged Particle ◽  
Charged Particle Multiplicities

scholarly journals Amplitude of Sunspot-Dependent Radiocarbon Variations: Data from Corals and Wine

Radiocarbon ◽  
1985 ◽  
Vol 27 (1) ◽  
pp. 111-115
Author(s):  
Mordeckai Magaritz ◽  
Israel Carmi ◽  
Ziv Sirkes
Keyword(s):  
Theoretical Analysis ◽  
Theoretical Calculation ◽  
Production Rate ◽  
Sunspot Cycle ◽  
Published Data ◽  
Earth Surface ◽  
The Earth ◽  
Surface System ◽  
Experimental Values

It has been suggested that the sunspot cycle modulates the production rate of radionuclides in the atmosphere and that these modulations can be traced in various parts of the earth surface system. On the basis of a theoretical analysis, Damon, Sternberg, and Radnell (1983) have concluded that the effects of the 11-yr cycle of sunspots should be observable in 14C data provided the measurements are done at a 2 permil (sd) level. This conclusion is based on calculations using models discussed by Lingenfelter and Ramaty (1970) and by O'Brien (1979) and on the 14C inventory modified from Damon, Lerman, and Long (1978). In this note we compare the amplitude estimate of Damon, Sternberg, and Radnell (1983), who calculated a representative peak-to-peak variation of 1.7‰ in 14C for the sunspot cycle between 1848 and 1856, with experimental values derived from recently published data. We find the experimental value to be larger by a significant factor from the theoretical calculation.

A strong isotopic effect in prescission charged particle multiplicities

1995 ◽  
Vol 353 (4) ◽  
pp. 432-437 ◽  
Author(s):  
N.V. Eremin ◽  
G. Giardina ◽  
I.I. Gontchar
Keyword(s):  
Charged Particle ◽  
Isotopic Effect ◽  
Charged Particle Multiplicities

Combined analysis of midrapidity transverse momentum spectra of the charged pions and kaons, protons and antiprotons in p+p and Pb+Pb collisions at (snn)1/2 = 2.76 and 5.02 TeV at the LHC

2020 ◽  
Vol 35 (29) ◽  
pp. 2050237
Author(s):  
Khusniddin K. Olimov ◽  
Shakhnoza Z. Kanokova ◽  
Alisher K. Olimov ◽  
Kobil I. Umarov ◽  
Boburbek J. Tukhtaev ◽  
...  
Keyword(s):  
Transverse Momentum ◽  
Center Of Mass ◽  
Heavy Ion ◽  
Transverse Flow ◽  
Alice Collaboration ◽  
Momentum Spectra ◽  
Charged Pions ◽  
Transverse Momentum Spectra ◽  
Tsallis Distribution ◽  
Freeze Out

The experimental transverse momentum spectra of the charged pions and kaons, protons and antiprotons, produced at midrapidity in [Formula: see text] collisions at [Formula: see text] and 5.02 TeV, central (0–5%) and peripheral (60–80%) Pb[Formula: see text]+[Formula: see text]Pb collisions at [Formula: see text] TeV, central (0–5%), semicentral (40–50%) and peripheral (80–90%) Pb[Formula: see text]+[Formula: see text]Pb collisions at [Formula: see text] TeV, measured by ALICE collaboration, were analyzed using the Tsallis distribution function as well as Hagedorn formula with the embedded transverse flow. To exclude the influence (on the results) of different available fitting [Formula: see text] ranges in the analyzed collisions, we compare the results obtained from combined (simultaneous) fits of midrapidity spectra of the charged pions and kaons, protons and antiprotons with the above theoretical model functions using the identical fitting [Formula: see text] ranges in [Formula: see text] as well as Pb[Formula: see text]+[Formula: see text]Pb collisions at [Formula: see text] and 5.02 TeV. Using the combined fits with the thermodynamically consistent Tsallis distribution as well as the simple Tsallis distribution without thermodynamical description, it is obtained that the global temperature [Formula: see text] and non-extensivity parameter [Formula: see text] slightly increase (consistently for all the particle types) with an increase in center-of-mass (c.m.) energy [Formula: see text] of [Formula: see text] collisions from 2.76 TeV to 5.02 TeV, indicating that the more violent and faster [Formula: see text] collisions at [Formula: see text] TeV result in a smaller degree of thermalization (higher degree of non-equilibrium) compared to that in [Formula: see text] collisions at [Formula: see text] TeV. The [Formula: see text] values for pions and kaons proved to be very close to each other, whereas [Formula: see text] for protons and antiprotons proved to be significantly lower than that for pions and kaons, that is [Formula: see text]. The results of the combined fits using Hagedorn formula with the embedded transverse flow are consistent with practically no (zero) transverse (radial) flow in [Formula: see text] collisions at [Formula: see text] and 5.02 TeV. Using Hagedorn formula with the embedded transverse flow, it is obtained that the value of the (average) transverse flow velocity increases and the temperature [Formula: see text] decreases with an increase in collision centrality in Pb[Formula: see text]+[Formula: see text]Pb collisions at [Formula: see text] and 5.02 TeV, which is in good agreement with the results of the combined Boltzmann–Gibbs blast-wave fits to the particle spectra in Pb[Formula: see text]+[Formula: see text]Pb collisions at [Formula: see text] and 5.02 TeV in recent works of ALICE collaboration. The temperature [Formula: see text] parameter, which approximates the kinetic freeze-out temperature, was shown to coincide in central (0–5%) Pb[Formula: see text]+[Formula: see text]Pb collisions at [Formula: see text] and 5.02 TeV, which implies, taking into account the results of our previous analysis, that kinetic freeze-out temperature stays practically constant in central heavy-ion collisions in [Formula: see text] GeV energy range.

scholarly journals Fluctuations in produced charged particle multiplicities in relativistic nuclear collisions for simulated events

2019 ◽  
Vol 1258 ◽  
pp. 012010
Author(s):  
M. Ayaz Ahmad ◽  
Jalal Hasan Baker ◽  
Mir Hashim Rasool ◽  
Shafiq Ahmad ◽  
R. Dobra ◽  
...  
Keyword(s):  
Charged Particle ◽  
Nuclear Collisions ◽  
Relativistic Nuclear Collisions ◽  
Charged Particle Multiplicities

Thermal equilibration behind an ionizing shock

1966 ◽  
Vol 26 (3) ◽  
pp. 459-479 ◽  
Author(s):  
H. Wong ◽  
D. Bershader
Keyword(s):  
Refractive Index ◽  
Theoretical Analysis ◽  
Thermal Equilibrium ◽  
Mass Density ◽  
Relaxation Times ◽  
Ionization Mechanism ◽  
Density Profiles ◽  
Physical Mechanisms ◽  
Thermal Equilibration ◽  
Equilibrium Region

The physical mechanisms underlying the relaxation process leading to thermal equilibrium behind ionizing shock waves in argon have been studied through use of optical techniques. The non-equilibrium condition in the relaxation region was investigated experimentally by measuring the shift in the fringes due to a change in the refractive index of the medium with a Mach–Zehnder interferometer. Both electron- and mass-density profiles from the shock front to the equilibrium region were determined. The experimental work has been supplemented by a theoretical analysis of the ionization mechanism to explain the measured profiles and relaxation times.

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