scholarly journals Event Shape and Multiplicity Dependence of Freeze-Out Scenario and System Thermodynamics in Proton+Proton Collisions at s = 13   TeV Using PYTHIA8

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Sushanta Tripathy ◽  
Ashish Bisht ◽  
Raghunath Sahoo ◽  
Arvind Khuntia ◽  
Malavika Panikkassery Salvan
Keyword(s):  
Charged Particle ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Event Generator ◽  
Particle Multiplicity ◽  
Event Shape ◽  
Charged Particle Multiplicity ◽  
Pp Collisions ◽  
Alice Experiment ◽  
Nonextensive Statistics

Recent observations of QGP-like conditions in high-multiplicity pp collisions from ALICE experiment at the LHC warrant an introspection whether to use pp collisions as a baseline measurement to characterize heavy-ion collisions for the possible formation of a Quark-Gluon Plasma. A double differential study of the particle spectra and thermodynamics of the produced system as a function of charged-particle multiplicity and transverse spherocity in pp collisions would shed light on the underlying event dynamics. Transverse spherocity, one of the event shape observables, allows to separate the events in terms of jetty and isotropic events. We analyse the identified particle transverse momentum ( p T ) spectra as a function of charged-particle multiplicity and transverse spherocity using Tsallis nonextensive statistics and Boltzmann-Gibbs Blast-Wave (BGBW) model in pp collisions at s = 13   TeV using PYTHIA8 event generator. The extracted parameters such as temperature ( T ), radial flow ( β ), and nonextensive parameter ( q ) are shown as a function of charged-particle multiplicity for different spherocity classes. We observe that the isotropic events approach thermal equilibrium while the jetty ones remain far from equilibrium. We argue that, while studying the QGP-like conditions in small systems, one should separate the isotropic events from the spherocity-integrated events, as the production dynamics are different.

scholarly journals (Anti-)deuteron production in pp collisions at $$\sqrt{s}=13 \ \text {TeV}$$

2020 ◽  
Vol 80 (9) ◽  
Author(s):  
S. Acharya ◽  
◽  
D. Adamová ◽  
A. Adler ◽  
J. Adolfsson ◽  
...  
Keyword(s):  
Charged Particle ◽  
Formation Mechanism ◽  
Bound States ◽  
High Energy ◽  
Light Nuclei ◽  
Particle Multiplicity ◽  
Charged Particle Multiplicity ◽  
Pp Collisions ◽  
Alice Experiment ◽  
Deuteron Production

AbstractThe study of (anti-)deuteron production in pp collisions has proven to be a powerful tool to investigate the formation mechanism of loosely bound states in high-energy hadronic collisions. In this paper the production of $$\text {(anti-)deuterons}$$ (anti-)deuterons is studied as a function of the charged particle multiplicity in inelastic pp collisions at $$\sqrt{s}=13$$ s = 13 TeV using the ALICE experiment. Thanks to the large number of accumulated minimum bias events, it has been possible to measure (anti-)deuteron production in pp collisions up to the same charged particle multiplicity ($${\mathrm {d} N_{ch}/\mathrm {d} \eta } \sim 26$$ d N ch / d η ∼ 26 ) as measured in p–Pb collisions at similar centre-of-mass energies. Within the uncertainties, the deuteron yield in pp collisions resembles the one in p–Pb interactions, suggesting a common formation mechanism behind the production of light nuclei in hadronic interactions. In this context the measurements are compared with the expectations of coalescence and statistical hadronisation models (SHM).

scholarly journals A Baseline Study of the Event-Shape and Multiplicity Dependence of Chemical Freeze-Out Parameters in Proton-Proton Collisions at \( {\sqrt{s}} \) = 13 TeV Using PYTHIA8

Physics ◽  
2020 ◽  
Vol 2 (4) ◽  
pp. 679-694
Author(s):  
Rutuparna Rath ◽  
Arvind Khuntia ◽  
Sushanta Tripathy ◽  
Raghunath Sahoo
Keyword(s):  
High Energy ◽  
Monte Carlo Event ◽  
Event Generator ◽  
Particle Multiplicity ◽  
Event Shape ◽  
Charged Particle Multiplicity ◽  
Pp Collisions ◽  
Proton Proton ◽  
Chemical Freeze ◽  
Freeze Out

The event-shape and multiplicity dependence of the chemical freeze-out temperature (Tch), freeze-out radius (R), and strangeness saturation factor (γs) are obtained by studying the particle yields from the PYTHIA8 Monte Carlo event generator in proton-proton (pp) collisions at the centre-of-mass s = 13 TeV. Spherocity is one of the transverse event-shape techniques to distinguish jetty and isotropic events in high-energy collisions and helps in looking into various observables in a more differential manner. In this study, spherocity classes are divided into three categories, namely (i) spherocity integrated, (ii) isotropic, and (iii) jetty. The chemical freeze-out parameters are extracted using a statistical thermal model as a function of the spherocity class and charged particle multiplicity in the canonical, strangeness canonical, and grand canonical ensembles. A clear observation of the multiplicity and spherocity class dependence of Tch, R, and γs is observed. A final state multiplicity, Nch≥ 30 in the forward multiplicity acceptance of the ALICE detector appears to be a thermodynamic limit, where the freeze-out parameters become almost independent of the ensembles. This study plays an important role in understanding the particle production mechanism in high-multiplicity pp collisions at the Large Hadron Collider (LHC) energies in view of a finite hadronic phase lifetime in small systems.

Sudden increase in the degrees of freedom in dense QCD matter

2021 ◽  
Author(s):  
Aditya Nath Mishra ◽  
Guy Paić ◽  
C. Pajares ◽  
R. P. Scharenberg ◽  
B. K. Srivastava
Keyword(s):  
Charged Particle ◽  
Energy Density ◽  
Heavy Ion Collisions ◽  
Degrees Of Freedom ◽  
Initial Temperature ◽  
Heavy Ion ◽  
Particle Multiplicity ◽  
Sudden Increase ◽  
Alice Experiment ◽  
Ion Collisions

In this paper, we analyzed charged particle transverse momentum spectra in high multiplicity events in proton–proton and nucleus–nucleus collisions at LHC energies from the ALICE experiment using the color string percolation model (CSPM). The color reduction factor and associated string density parameters are extracted for various multiplicity classes in [Formula: see text] collisions and centrality classes for heavy-ion collisions at various LHC energies to study the effect of collision geometry and collision energy. These parameters are used to extract the thermodynamical quantities temperature and the energy density of the hot nuclear matter. A universal scaling is observed in initial temperature when studied as a function of charged particle multiplicity scaled by transverse overlap area. From the measured initial energy density [Formula: see text] and the initial temperature T, a dimensionless quantity [Formula: see text] is constructed which is used to obtain the degrees of freedom (DOF) of the deconfined phase. A two-step behavior and a sudden increase in DOF of [Formula: see text]47 for the ideal gas, above the hadronization temperature (T [Formula: see text] 210[Formula: see text]MeV), are observed in case of heavy-ion collisions at LHC energies.

Charged particle multiplicity distributions in pp collisions at ISR energies

1977 ◽  
Vol 129 (3) ◽  
pp. 365-389 ◽  
Author(s):  
W. Thomé ◽  
K. Eggert ◽  
K. Giboni ◽  
H. Lisken ◽  
P. Darriulat ◽  
...  
Keyword(s):  
Charged Particle ◽  
Particle Multiplicity ◽  
Charged Particle Multiplicity ◽  
Pp Collisions ◽  
Multiplicity Distributions

scholarly journals Measurement of the Charged-Particle Multiplicity in pp Collisions at 102GeVc

1972 ◽  
Vol 29 (25) ◽  
pp. 1686-1688 ◽  
Author(s):  
J. W. Chapman ◽  
N. Green ◽  
B. P. Roe ◽  
A. A. Seidl ◽  
D. Sinclair ◽  
...  
Keyword(s):  
Charged Particle ◽  
Particle Multiplicity ◽  
Charged Particle Multiplicity ◽  
Pp Collisions

scholarly journals Measurement of J/Ψ production as a function of multiplicity in pp and p-Pb collisions with ALICE

2018 ◽  
Vol 182 ◽  
pp. 02064 ◽  
Author(s):  
Anisa Khatun ◽  
Keyword(s):  
Charged Particle ◽  
Theoretical Model ◽  
Electromagnetic Calorimeter ◽  
Particle Multiplicity ◽  
Charged Particle Multiplicity ◽  
Pp Collisions ◽  
Proton Proton ◽  
Model Predictions

The increase of hard probe production as a function of the charged particle multiplicity in proton-proton and proton-lead collisions is considered to be an interesting observable for the study of multiple parton interactions. In the present work, the correlation between J/Ψ production and charged particle multiplicity has been reviewed in pp collisions at √s = 7 and 13 TeV and p-Pb collisions at √sNN = 5.02 TeV at mid- and forward rapidities. The J/√ measurement in pp collisions at √s = 13 TeV using events triggered by the ALICE electromagnetic calorimeter at midrapidity is discussed in this report, too. An increment of the relative J/Ψ yields has been observed as a function of the multiplicity. The results have also been compared to theoretical model predictions.

scholarly journals Transverse energy and charged particle production in heavy-ion collisions: From RHIC to LHC

2014 ◽  
Vol 23 (04) ◽  
pp. 1450024 ◽  
Author(s):  
Raghunath Sahoo ◽  
Aditya Nath Mishra
Keyword(s):  
Charged Particle ◽  
Energy Production ◽  
Transverse Energy ◽  
Particle Production ◽  
Hadron Collider ◽  
Heavy Ion ◽  
Universal Function ◽  
Particle Multiplicity ◽  
Charged Particle Multiplicity ◽  
Relativistic Heavy Ion Collider

We study the charged particle and transverse energy production mechanism from AGS, SPS, Relativistic Heavy-Ion Collider (RHIC) to Large Hadron Collider (LHC) energies in the framework of nucleon and quark participants. At RHIC and LHC energies, the number of nucleons-normalized charged particle and transverse energy density in pseudorapidity, which shows a monotonic rise with centrality, turns out to be an almost centrality independent scaling behavior when normalized to the number of participant quarks. A universal function which is a combination of logarithmic and power-law, describes well the charged particle and transverse energy production both at nucleon and quark participant level for the whole range of collision energies. Energy dependent production mechanisms are discussed both for nucleonic and partonic level. Predictions are made for the pseudorapidity densities of transverse energy, charged particle multiplicity and their ratio (the barometric observable, [Formula: see text]) at mid-rapidity for Pb + Pb collisions at [Formula: see text]. A comparison with models based on gluon saturation and statistical hadron gas is made for the energy dependence of [Formula: see text].

scholarly journals Charged-particle production as a function of multiplicity and transverse spherocity in pp collisions at $$ \sqrt{\mathbf{s}} =\mathbf{5.02}$$ and 13 TeV

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
S. Acharya ◽  
◽  
D. Adamová ◽  
S. P. Adhya ◽  
A. Adler ◽  
...  
Keyword(s):  
Charged Particle ◽  
Particle Production ◽  
Functional Form ◽  
Good Description ◽  
Charged Particles ◽  
Particle Multiplicity ◽  
Charged Particle Multiplicity ◽  
Pp Collisions ◽  
Kinematic Range ◽  
Charged Particle Production

Abstract We present a study of the inclusive charged-particle transverse momentum ($$p_{\mathrm{T}}$$pT) spectra as a function of charged-particle multiplicity density at mid-pseudorapidity, $$\mathrm{d}N_{\mathrm{ch}}/\mathrm{d}\eta $$dNch/dη, in pp collisions at $$\sqrt{s}=5.02$$s=5.02 and 13 TeV covering the kinematic range $$|\eta |<0.8$$|η|<0.8 and $$0.15<p_{\mathrm{T}} <20$$0.15<pT<20 GeV/c. The results are presented for events with at least one charged particle in $$|\eta |<1$$|η|<1 (INEL$$\,>0$$>0). The $$p_\mathrm{T}$$pT spectra are reported for two multiplicity estimators covering different pseudorapidity regions. The $$p_{\mathrm{T}}$$pT spectra normalized to that for INEL$$\,>0$$>0 show little energy dependence. Moreover, the high-$$p_{\mathrm{T}}$$pT yields of charged particles increase faster than the charged-particle multiplicity density. The average $${ p}_{\mathrm{T}}$$pT as a function of multiplicity and transverse spherocity is reported for pp collisions at $$\sqrt{s}=13$$s=13 TeV. For low- (high-) spherocity events, corresponding to jet-like (isotropic) events, the average $$p_\mathrm{T}$$pT is higher (smaller) than that measured in INEL$$\,>0$$>0 pp collisions. Within uncertainties, the functional form of $$\langle p_{\mathrm{T}} \rangle (N_{\mathrm{ch}})$$⟨pT⟩(Nch) is not affected by the spherocity selection. While EPOS LHC gives a good description of many features of data, PYTHIA overestimates the average $$p_{\mathrm{T}}$$pT in jet-like events.

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