Multiplicity dependencies of midrapidity transverse momentum spectra of identified charged particles in p+p collisions at (s)1/2 = 13 TeV at LHC

Olimov, Khusniddin K.; Liu, Fu‐Hu; Musaev, Kobil A.; Olimov, K.; Tukhtaev, Boburbek J.; Yuldashev, B. S.; Saidkhanov, Nasir Sh.; Umarov, Kobil I.; Gulamov, K. G.

doi:10.1142/s0217751x21501499

“…The n and in the equation are two free parameters of the function. Moreover, the Tsallis function 15 – 18 can excellently describe the and invariant distribution measured in pp collisions at high energies. There are several version of the Tsallis function that can give good fit results to the spectra, however, the following expression is a simple version of the Tsallis function 22 that describes the invariant spectra of particles in terms of the effective temperature and non-extensivity parameter q which accounts for the deviation of the spectra from the usual Boltzmann–Gibbs exponential distribution function.…”

Section: Methods and Modelsmentioning

confidence: 99%

“…The temperature at the kinetic freeze-out stage ( ), the effective temperature ( ) and the average transverse flow velocity ( ) are extracted by fitting the data with these statistical functions. and are obtained by using a modified Hagedorn function with embedded transverse flow velocity 15 – 18 . In addition, is extracted by using the Tsallis distribution function 19 – 23 .…”

Section: Introductionmentioning

confidence: 99%

Pseudorapidity dependence of the bulk properties of hadronic medium in pp collisions at 7 TeV

Ajaz

¹

,

Ismail

²

,

Waqas

³

et al. 2022

Sci Rep

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The measured charged particle $$p_T$$ p T spectra in proton-proton collisions obtained by the CMS experiment at CERN is compared with the simulation results of EPOS–LHC and Pythia8.24 models at 7 TeV center-of-mass energy. The Pythia8.24 model describes the experimental data very well, particularly in the high $$p_T$$ p T region. The model also predicts the $$p_T$$ p T spectra for $$|$$ | $$\eta $$ η $$|$$ | < 2.4 at 0 $$\le $$ ≤ $$p_T$$ p T $$\le $$ ≤ 6 $$\text {GeV/}c$$ GeV/ c . The EPOS–LHC model underpredicts the $$p_T$$ p T spectra from 0.1 to 2 $$\text {GeV/}c$$ GeV/ c in all $$\eta $$ η bins for about 20% and the $$p_T$$ p T spectrum from 0.1 to 4.2 $$\text {GeV/}c$$ GeV/ c for $$|$$ | $$\eta $$ η $$|$$ | < 2.4 by about 15% while reasonably predicts well for $$p_T$$ p T > 4.2 $$\text {GeV/}c$$ GeV/ c within the experimental errors. Furthermore, to get information about collective properties of the hadronic matter, modified Hagedorn function with embedded transverse flow velocity and thermodynamically consistent Tsallis distribution functions are used to fit the experimental data and simulated results. The values of $$\chi ^2/ndf$$ χ 2 / n d f show that the functions fit the data and simulation results well. The parameter extracted by the functions: $$\beta _T$$ β T , $$T_0$$ T 0 , and $$T_{eff}$$ T eff decreases with increasing $$\eta $$ η . The decrease in $$\beta _T$$ β T with increasing $$\eta $$ η is due to the large energy deposition in lower rapidity bins producing rapid expansion due to large pressure gradient resulting quick expansion of the fireball. Similarly, large energy transfer in the lower pseudo-rapidity bin results in higher degree of excitation of the system which results larger values of $$T_0$$ T 0 and $$T_{eff}$$ T eff . The values of the fit constant $$N_0$$ N 0 increase with $$\eta $$ η where the values of $$N_0$$ N 0 extracted from Pythia8.24 are closer to the data than the EPOS–LHC model. The Pythia8.24 model has better prediction than the EPOS–LHC model which might be connected to its flow-like features and color re-connections resulting from different Parton interactions in the initial and final state.

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“…The different transverse flow models have been incorporated into Tsallis statistics to describe the p t distributions of hadrons in high-energy heavy-ion and proton-proton collisions at the RHIC and LHC. In most cases, the Blast-Wave model with Boltzmann-Gibbs statistics (the BGBW model) [26][27][28], the Blast-Wave model with Tsallis statistics (the TBW model) [29,30], the Tsallis distribution with transverse flow effect-improved Tsallis distribution [30][31][32], and the Hagedorn formula (function) with transverse flow [11,16,21,33] have been used to estimate the kinetic freeze-out temperature and transverse expansion velocity.…”

Section: Introductionmentioning

confidence: 99%

“…However, as indicated in [34], it is not feasible to assign the physical meaning to collective properties, such as kinetic freeze-out temperature or radial transverse flow velocity, extracted from separate model fits to each particle type. The simultaneous model fits to p t distributions of various particle species in a studied collision system, performed by keeping the temperature and transverse flow velocity as the common (shared) fitted parameters for all particle species, can produce the physically meaningful collective parameters of a collision system [16,21,33,34]. The combined (global) fits have proved to be quite efficient for the extraction of collective properties and the comparison of different collision systems with the help of few parameters [16,21,33,34].…”

Section: Introductionmentioning

confidence: 99%

Multiplicity Dependencies of Midrapidity Transverse Momentum Distributions of Identified Charged Particles in Proton-Proton Collisions at (s)1/2 = 7 TeV at the LHC

Olimov

¹

,

Liu

²

,

Musaev

³

et al. 2022

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Dependencies of midrapidity pt distributions of the charged pions and kaons, protons and antiprotons on charged-particle multiplicity density (<dNch/dη>) in inelastic proton-proton collisions at (s)1/2 = 7 TeV at the LHC, measured by ALICE Collaboration, are investigated. The simultaneous minimum χ2 fits with the Tsallis function with thermodynamical consistence and the Hagedorn function with included transverse flow have well-described the pt spectra of the particle species in the ten studied groups of charged-particle multiplicity density. The effective temperatures, T, of the Tsallis function with thermodynamical consistence have shown a steady rise with increasing the charged-particle multiplicity in proton-proton collisions at (s)1/2 = 7 TeV, in agreement with the similar result obtained recently in proton-proton collisions at (s)1/2 = 13 TeV at the LHC. The respective T versus <dNch/dη> dependence in proton-proton collisions at (s)1/2 = 7 TeV is reproduced quite well by the simple power function with the same value (≈ 1/3) of the exponent parameter as that extracted in proton-proton collisions at (s)1/2 = 13 TeV. The identical power dependence T~ε1/3 between the initial energy density and effective temperature of the system has been observed in proton-proton collisions at (s)1/2 = 7 and 13 TeV. We have observed that the transverse radial flow emerges at <dNch/dη> ≈ 6 and then increases, becoming substantial at larger multiplicity events in proton-proton collisions at (s)1/2 = 7 TeV. We have estimated, analyzing T0 and ⟨βt⟩ versus <dNch/dη> dependencies, that the possible onset of deconfinement phase transition in proton-proton collisions at (s)1/2 = 7 TeV occurs at <dNch/dη> ≈ 6.1 ± 0.3, which is close to the corresponding recent estimate (<dNch/dη> ≈ 7.1 ± 0.2) in proton-proton collisions at (s)1/2 = 13 TeV. The corresponding critical energy densities for probable onset of deconfinement phase transition in proton-proton collisions at (s)1/2 = 7 and 13 TeV at the LHC have been estimated to be 0.67 ± 0.03 and 0.76 ± 0.02 GeV/fm3, respectively.

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“…Understanding the characteristics of particle productions is very necessary for researchers to study the evolution of collision system and interactions among various particles. [ 30–37 ]…”

Section: Introductionmentioning

confidence: 99%

An Energy Independent Scaling of Transverse Momentum Spectra of Direct (Prompt) Photons from Two‐Body Processes in High‐Energy Proton–Proton Collisions

Zhang

¹

,

Gao

²

,

Liu

³

et al. 2022

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Transverse momentum spectra of direct (prompt) photons from two-body processes in high-energy proton-proton (p+p) collisions are analyzed in this paper. The experimental invariant cross-sections are collected at mid-rapidity in p+p collisions measured by the UA6, CCOR, R806, R110, PHENIX, NA24, CMS, ALICE, and ATLAS Collaborations over a center-of-mass energy range from 24.3 GeV to 13 TeV. In fitting the data, different kinds of functions are used which include the revised Tsallis-Pareto-type function (the TP-like function) at the particle level, the convolution of two TP-like functions at the quark level, and the root-sum-of-squares of two revised Tsallis-like functions in which the quark chemical potentials 𝝁 i = 𝝁 B ∕3 or 𝝁 i = 0, where 𝝁 B is the baryon chemical potential. The values of three main free parameters have been extracted: the effective temperature T, power index n 0 (or entropy index q), and correction index a 0 . After analyzing the changing trends of the parameters, it is found that T, q, and a 0 increase and n 0 decreases with the increase of collision energy. Based on the analyses of transverse momentum spectra, an energy independent scaling, that is, the x T scaling, is obtained.

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Multiplicity dependencies of midrapidity transverse momentum spectra of identified charged particles in p+p collisions at (s)1/2 = 13 TeV at LHC

Cited by 23 publications

References 51 publications

Pseudorapidity dependence of the bulk properties of hadronic medium in pp collisions at 7 TeV

Pseudorapidity dependence of the bulk properties of hadronic medium in pp collisions at 7 TeV

Multiplicity Dependencies of Midrapidity Transverse Momentum Distributions of Identified Charged Particles in Proton-Proton Collisions at (s)1/2 = 7 TeV at the LHC

An Energy Independent Scaling of Transverse Momentum Spectra of Direct (Prompt) Photons from Two‐Body Processes in High‐Energy Proton–Proton Collisions

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