Pis’ma v ZhETF, vol. 109, iss. 8, pp. 507 - 508

April 25

Distributions of charged particles’ transverse momentum and

pseudorapidity in pp collisions at 0.9 TeV

Q.Ali⁺, Y.Ali⁺¹⁾, M.Haseeb⁺, M.Ajaz^∗

⁺Department of Physics, Commission on Science and Technology for Sustainable Development in the South (COMSATS) University,

Park Road, 44000 Islamabad, Pakistan

^∗Department of Physics, Abdul Wali Khan University Mardan, 23200 Mardan, Pakistan

Submitted 14 January 2019

Resubmitted 27 February 2019

Accepted 27

February 2019

DOI: 10.1134/S0370274X19080010

The p_T -spectra of hadrons can be used to deduce

lisions for the pseudorapidity interval of |η| < 2.5 at

the mechanism of particle production in (proton-proton)

√s = 0.9 TeV.

pp collisions. The study of charged particle production

in pp collisions at high energies provides dynamics of

hard as well as soft interactions [1-4]. The perturba-

tive Quantum Chromodynamics (pQCD) quantitatively

describe, large momentum transfer, hard parton-parton

scattering processes [5].

Measurements of high-p_T charged particles produc-

tion at Large Hadron Collider (LHC) energies play a vi-

tal role to constrain fragmentation and parton distribu-

tion functions in current pQCD calculations of next-to-

Leading-Order (NLO) [6]. However, production of parti-

cle is dominated by soft interactions at low momentum

where most of the particles are produced.

We have studied the charged particles spectra for

the pseudorapidity region of |η| < 2.5, the multiplicity

of charged particles, its dependence on p_T as well as on

η and the relationship between average p_T and charged

particles multiplicity in pp collisions at

√s = 0.9 TeV.

For simulations, we have used EPOS-LHC, EPOS-1.99,

QGSJETII-04, and SIBYLL-2.3c models and compared

Fig. 1. (Color online) Comparison of the models’ predic-

their predictions with the experimental data of AT-

tions of pT -distributions of the differential yield of hadrons

for |η| < 2.5 with the ATLAS data. Filled circle is used to

LAS experiment. For the p_T distribution, predictions

represent experimental data, solid blue line for EPOS-1.99,

of the Sibyll-2.3c are matching with the experimental

solid red line shows EPOS-LHC, solid green line shows the

data in a region of 0.5 < p_T < 0.8 GeV/c and EPOS-

QGSJETII-04 and orange yellow shows the SIBYLL-2.3c

1.99 model results are near to the experimental data

model

for 0.5 < p_T < 1.5 GeV/c. For the case of average p_T ,

EPOS-LHC and Sibyll-2.3c predictions are closer to the

experimental data. For the pseudorapidity charged par-

Full text of the paper is published in JETP Letters

ticle density distributions QGSJETII-04 model predic-

journal. DOI: 10.1134/S0021364019080010

tions are better describing the experimental data.

Figure 1 shows the comparison of charged particle

multiplicity distributions as a function of p_T in pp col-

1. F. Abe, D. Amidei, G. Apollinari et al. (Collaboration),

Phys. Rev. Lett. 62, 613 (1989).

2. F. Abe, D. Amidei, and G. Apollinari et al. (Collabora-

¹⁾e-mail: yasir_ali@comsats.edu.pk

tion), Phys. Rev. Lett. 64, 157 (1990).

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