scholarly journals First measurement of large area jet transverse momentum spectra in heavy-ion collisions

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
◽  
A. M. Sirunyan ◽  
A. Tumasyan ◽  
W. Adam ◽  
F. Ambrogi ◽  
...  
Keyword(s):  
Center Of Mass ◽  
Heavy Ion ◽  
Nucleon Nucleon ◽  
Large Area ◽  
Loss Mechanism ◽  
Strong Suppression ◽  
Center Of Mass Energy ◽  
Momentum Spectra ◽  
Transverse Momentum Spectra ◽  
Jet Energy

Abstract Jet production in lead-lead (PbPb) and proton-proton (pp) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV is studied with the CMS detector at the LHC, using PbPb and pp data samples corresponding to integrated luminosities of 404 μb−1 and 27.4 pb−1, respectively. Jets with different areas are reconstructed using the anti-kT algorithm by varying the distance parameter R. The measurements are performed using jets with transverse momenta (pT) greater than 200 GeV and in a pseudorapidity range of |η| < 2. To reveal the medium modification of the jet spectra in PbPb collisions, the properly normalized ratio of spectra from PbPb and pp data is used to extract jet nuclear modification factors as functions of the PbPb collision centrality, pT and, for the first time, as a function of R up to 1.0. For the most central collisions, a strong suppression is observed for high-pT jets reconstructed with all distance parameters, implying that a significant amount of jet energy is scattered to large angles. The dependence of jet suppression on R is expected to be sensitive to both the jet energy loss mechanism and the medium response, and so the data are compared to several modern event generators and analytic calculations. The models considered do not fully reproduce the data.

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 Chemical Potentials of Light Flavor Quarks from Yield Ratios of Negative to Positive Particles in Au+Au Collisions at RHIC

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Ya-Qin Gao ◽  
Hai-Ling Lao ◽  
Fu-Hu Liu
Keyword(s):  
Transverse Momentum ◽  
Collision Energy ◽  
Center Of Mass ◽  
Star Collaboration ◽  
Strange Quarks ◽  
Center Of Mass Energy ◽  
Chemical Potentials ◽  
Momentum Spectra ◽  
200 Gev ◽  
Transverse Momentum Spectra

The transverse momentum spectra of π-, π+, K-, K+, p¯, and p produced in Au+Au collisions at center-of-mass energy sNN=7.7, 11.5, 19.6, 27, 39, 62.4, 130, and 200 GeV are analyzed in the framework of a multisource thermal model. The experimental data measured at midrapidity by the STAR Collaboration are fitted by the (two-component) standard distribution. The effective temperature of emission source increases obviously with the increase of the particle mass and the collision energy. At different collision energies, the chemical potentials of up, down, and strange quarks are obtained from the antiparticle to particle yield ratios in given transverse momentum ranges available in experiments. With the increase of logarithmic collision energy, the chemical potentials of light flavor quarks decrease exponentially.

scholarly journals Rapidity Dependent Transverse Momentum Spectra of Heavy Quarkonia Produced in Small Collision Systems at the LHC

2019 ◽  
Vol 2019 ◽  
pp. 1-17
Author(s):  
Li-Na Gao ◽  
Fu-Hu Liu ◽  
Bao-Chun Li
Keyword(s):  
Transverse Momentum ◽  
Hadron Collider ◽  
Center Of Mass ◽  
Lhcb Collaboration ◽  
Heavy Quarkonia ◽  
Proton Proton ◽  
Center Of Mass Energy ◽  
Inverse Power Law ◽  
Momentum Spectra ◽  
Transverse Momentum Spectra

The rapidity dependent transverse momentum spectra of heavy quarkonia (J/ψ and Υ mesons) produced in small collision systems such as proton-proton (pp) and proton-lead (p-Pb) collisions at center-of-mass energy (per nucleon pair) s (sNN) = 5-13 TeV are described by a two-component statistical model which is based on the Tsallis statistics and inverse power-law. The experimental data measured by the LHCb Collaboration at the Large Hadron Collider (LHC) are well fitted by the model results. The related parameters are obtained and the dependence of parameters on rapidity is analyzed.

scholarly journals A New Description of Transverse Momentum Spectra of Identified Particles Produced in Proton-Proton Collisions at High Energies

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Pei-Pin Yang ◽  
Fu-Hu Liu ◽  
Raghunath Sahoo
Keyword(s):  
Transverse Momentum ◽  
Center Of Mass ◽  
High Energy ◽  
Momentum Spectrum ◽  
Transverse Momentum Spectrum ◽  
Proton Proton ◽  
Center Of Mass Energy ◽  
Momentum Spectra ◽  
Quark Level ◽  
Transverse Momentum Spectra

The transverse momentum spectra of identified particles produced in high energy proton-proton p + p collisions are empirically described by a new method with the framework of the participant quark model or the multisource model at the quark level, in which the source itself is exactly the participant quark. Each participant (constituent) quark contributes to the transverse momentum spectrum, which is described by the TP-like function, a revised Tsallis–Pareto-type function. The transverse momentum spectrum of the hadron is the convolution of two or more TP-like functions. For a lepton, the transverse momentum spectrum is the convolution of two TP-like functions due to two participant quarks, e.g., projectile and target quarks, taking part in the collisions. A discussed theoretical approach seems to describe the p + p collisions data at center-of-mass energy s = 200     GeV , 2.76 TeV, and 13 TeV very well.

scholarly journals Analysis of kinetic freeze-out temperature and transverse flow velocity in nucleus–nucleus and proton–proton collisions at same center-of-mass energy

2021 ◽  
pp. 2150061
Author(s):  
M. Waqas ◽  
G. X. Peng ◽  
Z. Wazir ◽  
Hai-Ling Lao
Keyword(s):  
Transverse Momentum ◽  
Flow Velocity ◽  
Center Of Mass ◽  
Transverse Flow ◽  
Proton Proton ◽  
Center Of Mass Energy ◽  
Momentum Spectra ◽  
Transverse Momentum Spectra ◽  
Proton Proton Collisions ◽  
Transverse Flow Velocity

Transverse momentum spectra of different types of identified charged particles in central Gold–Gold (Au–Au) collisions and inelastic (INEL) or nonsingle diffractive (NSD) proton–proton (pp) collisions at the Relativistic Heavy Ion Collider (RHIC), as well as in central and peripheral Lead–Lead (Pb–Pb) collisions, and INEL or NSD pp collisions at the Large Hadron Collider (LHC) are analyzed by the blast-wave model with Tsallis statistics. The model results are approximately in agreement with the experimental data measured by STAR, PHENIX and ALICE Collaborations in special transverse momentum ranges. Kinetic freeze-out (KFO) temperature and transverse flow velocity are extracted from the transverse momentum spectra of the particles. It is shown that KFO temperature of the emission source depends on mass of the particles, which reveals the mass-dependent KFO scenario in collisions at RHIC and LHC. Furthermore, the KFO temperature and transverse flow velocity in central nucleus–nucleus (AA) collisions are larger than in peripheral collisions, and both of them are slightly larger in peripheral nucleus–nucleus collisions or almost equivalent to that in proton–proton collisions at the same center-of-mass energy which shows their similar thermodynamic nature.

Exploring Baryon Rich Matter with Heavy-Ion Collisions

2019 ◽  
Vol 64 (7) ◽  
pp. 583 ◽  
Author(s):  
S. Harabasz
Keyword(s):  
Center Of Mass ◽  
Heavy Ion ◽  
State Density ◽  
Heavy Nuclei ◽  
First Order ◽  
Center Of Mass Energy ◽  
Ion Collisions ◽  
Deconfinement Phase Transition ◽  
Ground State Density

Collisions of heavy nuclei at (ultra-)relativistic energies provide a fascinating opportunity to re-create various forms of matter in the laboratory. For a short extent of time (10-22 s), matter under extreme conditions of temperature and density can exist. In dedicated experiments, one explores the microscopic structure of strongly interacting matter and its phase diagram. In heavy-ion reactions at SIS18 collision energies, matter is substantially compressed (2–3 times ground-state density), while moderate temperatures are reached (T < 70 MeV). The conditions closely resemble those that prevail, e.g., in neutron star mergers. Matter under such conditions is currently being studied at the High Acceptance DiElecton Spectrometer (HADES). Important topics of the research program are the mechanisms of strangeness production, the emissivity of matter, and the role of baryonic resonances herein. In this contribution, we will focus on the important experimental results obtained by HADES in Au+Au collisions at 2.4 GeV center-of-mass energy. We will also present perspectives for future experiments with HADES and CBM at SIS100, where higher beam energies and intensities will allow for the studies of the first-order deconfinement phase transition and its critical endpoint.

scholarly journals Study of Dependence of Kinetic Freezeout Temperature on the Production Cross-Section of Particles in Various Centrality Intervals in Au–Au and Pb–Pb Collisions at High Energies

Entropy ◽  
2021 ◽  
Vol 23 (4) ◽  
pp. 488
Author(s):  
Muhammad Waqas ◽  
Guang-Xiong Peng
Keyword(s):  
Transverse Momentum ◽  
Flow Velocity ◽  
Production Cross ◽  
Center Of Mass ◽  
Wave Model ◽  
Transverse Flow ◽  
Peripheral Collisions ◽  
Momentum Spectra ◽  
Transverse Momentum Spectra ◽  
Transverse Flow Velocity

Transverse momentum spectra of π+, p, Λ, Ξ or Ξ¯+, Ω or Ω¯+ and deuteron (d) in different centrality intervals in nucleus–nucleus collisions at the center of mass energy are analyzed by the blast wave model with Boltzmann Gibbs statistics. We extracted the kinetic freezeout temperature, transverse flow velocity and kinetic freezeout volume from the transverse momentum spectra of the particles. It is observed that the non-strange and strange (multi-strange) particles freezeout separately due to different reaction cross-sections. While the freezeout volume and transverse flow velocity are mass dependent, they decrease with the resting mass of the particles. The present work reveals the scenario of a double kinetic freezeout in nucleus–nucleus collisions. Furthermore, the kinetic freezeout temperature and freezeout volume are larger in central collisions than peripheral collisions. However, the transverse flow velocity remains almost unchanged from central to peripheral collisions.

HYDJET SIMULATIONS OF ELLIPTIC FLOW IN HEAVY ION COLLISIONS AT THE LHC

2007 ◽  
Vol 16 (07n08) ◽  
pp. 1917-1922
Author(s):  
D. KROFCHECK ◽  
R. MAK ◽  
P. ALLFREY
Keyword(s):  
Hadron Collider ◽  
Center Of Mass ◽  
Elliptic Flow ◽  
Heavy Ion ◽  
Event Generator ◽  
Simulation Tool ◽  
Mass Energy ◽  
Relativistic Heavy Ion Collider ◽  
Center Of Mass Energy ◽  
Ion Collisions

At the Relativistic Heavy Ion Collider (RHIC) elliptic flow signals (v2) appear to be stronger than those measured at lower center-of-mass energies. With the beginning of heavy ion beams at the Large Hadron Collider (LHC) it is important to have a reliable tool for simulating v2 at the LHC Pb – Pb center-of-mass energy of 5.5 A TeV. In this work we used the heavy ion simulation tool HYDJET to study elliptic flow at the event generator level. The generator level elliptic flow v2 for Pb – Pb collisions was two-particle and four-particle cumulants.

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