scholarly journals String percolation in AA and p+p collisions

2019 ◽  
Vol 65 (3) ◽  
pp. 197 ◽  
Author(s):  
I. Bautista ◽  
C. Pajares ◽  
And J.E. Ramírez
Keyword(s):  
Experimental Data ◽  
Transverse Momentum ◽  
Density Ratio ◽  
Entropy Density ◽  
Pp Collisions ◽  
Proton Proton ◽  
Ridge Structure ◽  
Strangeness Enhancement ◽  
Bose Einstein ◽  
Proton Proton Collisions

A brief review of the string percolation model and its results are presented together with the comparison to experimental data. First, it is done an introduction to the quark-gluon phase diagram and the lattice results concerning the connement and the percolation of center domains. It is studied the interaction of the strings produced in nucleus-nucleus and proton-proton collisions showing how the string percolation arises. The main consequences of the string percolation, concerning the dependence on the energy and centrality, on the multiplicities and the mean transverse momentum are obtained comparing with experimental data. It is emphasized the non-abelian character of the color eld of the strings forming the cluster to reproduce the rise of the transverse momentum with multiplicity and the relative suppression of multiplicities. It is also studied dierent observables like multiplicity and transverse momentum distributions, dependence with multiplicity and transverse momentum correlations, forward-backward correlations, the strength of the Bose-Einstein correlations, dependence on the multiplicity of J/ψ  production and its possible suppression in pp collisions at high multiplicity, strangeness enhancement, elliptic ow, and ridge structure. The comparison with the data shows an overall agreement. The thermodynamical properties of the extended cluster formed in the collision are discussed computingits energy and entropy density, shear viscosity over entropy density ratio, bulk viscosity, sound speed and trace anomaly as a function of temperature, showing a remarkable agreement with lattice QCD evaluations. The string percolation can be regarded as the initial frame able to describe the collective behavior produced in AA and pp collisions.

Models prediction of hadrons production ratios in pp collisions at s = 7 TeV

2019 ◽  
Vol 34 (13) ◽  
pp. 1950090 ◽  
Author(s):  
M. Ajaz ◽  
M. Bilal ◽  
Y. Ali ◽  
M. K. Suleymanov ◽  
K. H. Khan
Keyword(s):  
Experimental Data ◽  
Transverse Momentum ◽  
Charged Particles ◽  
Hadron Production ◽  
Proton Proton ◽  
Proton Collisions ◽  
Particle Ratios ◽  
Production Models ◽  
Lhcb Detector ◽  
Proton Proton Collisions

The pseudorapidity [Formula: see text] dependence of charged-particles ratios in three transverse momentum [Formula: see text] regions, obtained by hadron production models, in proton–proton collisions at 7 TeV are compared with the measurements of LHCb detector. Compared to the experimental data, the [Formula: see text] ratios are independent of [Formula: see text] and [Formula: see text] and are very well predicted by all models (DPMJETIII, EPOS1.99, EPOS-LHC, HIJING1.383, QGSJETII-04 and Sibyll2.3c). All models predict the [Formula: see text] ratio at low [Formula: see text] for [Formula: see text], but underestimate afterward while reproducing the experimental data at medium and high [Formula: see text] very well. The [Formula: see text] ratio is described by the models very well at high [Formula: see text] in the low and medium [Formula: see text] region. At high [Formula: see text], models predict the experimental data well, except Sibyll2.3c that slightly overestimates. The [Formula: see text] ratio is predicted by EPOS1.99, HIJING and Sibyll at low [Formula: see text] and EPOS-LHC, EPOS1.99 and Sibyll predicted at high [Formula: see text] for low [Formula: see text]. For medium [Formula: see text], EPOS1.99 and Sibyll predict very well for [Formula: see text] while EPOS-LHC and HIJING models reproduce the data for [Formula: see text]. All models underpredict the [Formula: see text] ratio for [Formula: see text]. For the [Formula: see text] and [Formula: see text] ratios, only Sibyll and EPOS1.99 models could reproduce some regions of [Formula: see text] and [Formula: see text]. None of the models satisfactorily predict all the ratios. the same particle ratios are well described by most of the models while the discrepancies occur mostly in predicting the different particles ratios.

Distribution of strange particles transverse momentum and rapidity in high energy proton–proton collisions at s = 0.9 TeV at LHC

2019 ◽  
Vol 35 (05) ◽  
pp. 2050006
Author(s):  
Q. Ali ◽  
Y. Ali ◽  
U. Tabassam ◽  
M. Haseeb ◽  
M. Ikram
Keyword(s):  
Experimental Data ◽  
Transverse Momentum ◽  
Simulation Models ◽  
High Energy ◽  
Rapidity Distribution ◽  
Proton Proton ◽  
Proton Collisions ◽  
Strange Particles ◽  
Good Comparison ◽  
Proton Proton Collisions

In this paper, we have studied the spectra of strange particles in pp collision at [Formula: see text] = 0.9 TeV by using different simulation models, EPOS-1.99, SIBYLL-2.3c, QGSJETII-04 and EPOS-LHC. The transverse momentum and rapidity distribution in the [Formula: see text] range of [Formula: see text] GeV/c and [Formula: see text] GeV/c, respectively, are investigated for the strange particles, [Formula: see text], [Formula: see text], [Formula: see text]. Similarly, a comparative study is done for the ratio of [Formula: see text] and [Formula: see text] as a function of transverse momentum and rapidity. The validity of simulation models is tested by comparing simulation results to the CMS experimental data at [Formula: see text] = 0.9 TeV. For [Formula: see text] distributions, the EPOS-LHC model in the [Formula: see text] range [Formula: see text] GeV/c, [Formula: see text] GeV/c and in [Formula: see text] GeV/c while EPOS-1.99 model in the [Formula: see text] range [Formula: see text] GeV/c and QGSJETII-04 model in the [Formula: see text] range [Formula: see text] GeV/c as well as, [Formula: see text] GeV/c explain the experimental data well. For the, [Formula: see text] and [Formula: see text] versus transverse momentum distributions, EPOS-LHC model in the [Formula: see text] range of, [Formula: see text] GeV/c and [Formula: see text] GeV/c, EPOS-1.99 model in the [Formula: see text] range, [Formula: see text] GeV/c, SIBYLL-2.3c model in the [Formula: see text] range, [Formula: see text] GeV/c and QGSJETII-04 model in the [Formula: see text] range [Formula: see text] GeV/c explain the experimental data very well. Similarly, for [Formula: see text] and [Formula: see text] versus rapidity distribution QGSJETII-04 predictions in the rapidity region, [Formula: see text], [Formula: see text], and [Formula: see text], while EPOS-LHC model in the region, [Formula: see text], very well explained the experimental data. Although good comparison of the models predictions with the experimental data is observed, none of them completely describe the experimental data the spectra of strange particles over the entire [Formula: see text] and [Formula: see text] range.

scholarly journals SOFT RIDGE IN PROTON–PROTON COLLISIONS

2011 ◽  
Vol 26 (13) ◽  
pp. 963-966 ◽  
Author(s):  
M. YU. AZARKIN ◽  
I. M. DREMIN ◽  
A. V. LEONIDOV
Keyword(s):  
Degrees Of Freedom ◽  
Multiparticle Production ◽  
Pp Collisions ◽  
Proton Proton ◽  
Proton Collisions ◽  
Ridge Structure ◽  
Angular Correlations ◽  
Proton Proton Collisions

It is shown that the soft mechanism of multiparticle production by Lund hadronic strings formed by colliding constituent degrees of freedom generates a shape of angular correlations similar to the ridge structure observed in the pp collisions at 7 TeV at the LHC.

scholarly journals A Comparative Study of K±/π± Ratio in Proton-Proton Collisions at Different Energies: Experimental Results versus Model Simulation

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Swarnapratim Bhattacharyya ◽  
Maria Haiduc ◽  
Alina Tania Neagu ◽  
Elena Firu
Keyword(s):  
Experimental Data ◽  
Comparative Study ◽  
Model Simulation ◽  
Experimental Results ◽  
Pp Collisions ◽  
Proton Proton ◽  
Proton Collisions ◽  
Versus Model ◽  
Pion Multiplicity ◽  
Proton Proton Collisions

A detailed study of energy dependence of K+/π+, K-/π- and total kaon to pion multiplicity ratio K++K-/π++π-=K/π has been carried out in proton-proton (pp) collisions at s=6.3, 17.3, 62.4, 200, and 900 GeV and also at s=2.76 TeV and 7 TeV in the framework of UrQMD and DPMJET III model. Dependence of K+/π+ and K-/π- on energy shows different behavior for UrQMD and DPMJET III model. The presence of the horn-like structure in the variation of K+/π+ and K-/π- with energy for the experimental data is supported by the DPMJET III model. Experimentally it has been observed that as energy increases, the total kaon to pion multiplicity ratio K++K-/π++π-=K/π increases systematically for pp collisions at lower energies and becomes independent of energy in LHC energy regime. Our analysis on total kaon to pion multiplicity ratio K++K-/π++π-=K/π with UrQMD data is well supported by the experimental results obtained by different collaborations in different times. In case of DPMJET III data, the saturation of K/π ratio at LHC region has not been observed.

scholarly journals Search for squarks and gluinos in final states with jets and missing transverse momentum using 139 fb−1 of $$ \sqrt{s} $$ = 13 TeV pp collision data with the ATLAS detector

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
G. Aad ◽  
◽  
B. Abbott ◽  
D. C. Abbott ◽  
A. Abed Abud ◽  
...  
Keyword(s):  
Transverse Momentum ◽  
Hadron Collider ◽  
Atlas Detector ◽  
Simplified Model ◽  
Supersymmetric Particle ◽  
Final States ◽  
Proton Proton ◽  
Missing Transverse Momentum ◽  
First And Second Generation ◽  
Proton Proton Collisions

Abstract A search for the supersymmetric partners of quarks and gluons (squarks and gluinos) in final states containing jets and missing transverse momentum, but no electrons or muons, is presented. The data used in this search were recorded by the ATLAS experiment in proton-proton collisions at a centre-of-mass energy of $$ \sqrt{s} $$ s = 13 TeV during Run 2 of the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb−1. The results are interpreted in the context of various R-parity-conserving models where squarks and gluinos are produced in pairs or in association and a neutralino is the lightest supersymmetric particle. An exclusion limit at the 95% confidence level on the mass of the gluino is set at 2.30 TeV for a simplified model containing only a gluino and the lightest neutralino, assuming the latter is massless. For a simplified model involving the strong production of mass-degenerate first- and second-generation squarks, squark masses below 1.85 TeV are excluded if the lightest neutralino is massless. These limits extend substantially beyond the region of supersymmetric parameter space excluded previously by similar searches with the ATLAS detector.

scholarly journals Forward backward multiplicity correlations: a tool to study properties of the proton-proton collisions

2018 ◽  
Vol 172 ◽  
pp. 05008 ◽  
Author(s):  
Edgar Dominguez-Rosas ◽  
Eleazar Cuautle Flores
Keyword(s):  
Experimental Data ◽  
Hadron Production ◽  
Event Generator ◽  
Proton Proton ◽  
Proton Collisions ◽  
Electron Positron ◽  
Color Reconnection ◽  
Proton Proton Collisions ◽  
Production Mechanisms ◽  
Reconnection Model

Forward-backward multiplicity correlations have been used to study hadron production mechanisms in electron-positron, proton-proton and more recently in leadlead collisions. The experimental results on this correlations and its comparison to different models reveals an incomplete agreement. In this work, we present an study of forward backward multiplicity correlations in proton-proton collisions using PYTHIA event generator, at LHC energies. Detailed analysis is presented in the case of soft and hard QCD processes, incorporating color reconnection model as part of hadronization mechanism and multiple parton interactions effects in the correlations. Our results and its comparison to available experimental data suggest that this kind of correlations are great tools to characterize the events and gives the possibility to disentangle phenomena in hard and soft QCD processes.

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