Abstract
We study pion production in proton–proton (pp) and in central ^{7}Be + ^{9}Be and ^{40}text {Ar}+ ^{45}text {Sc} collisions at CERN super proton synchrotron (SPS) energies within the Angantyr model, whose pp dynamics are modeled by PYTHIA 8.303 event generator. We have tuned the parameters of the default multi-partonic interaction (MPI) mechanism in PYTHIA 8.303 to describe simultaneously the measured rapidity and transverse momentum distributions of pions in inelastic pp-collisions in the beam momentum range from 20 to 158 GeV/c. We explore the influence of the standard Lund fragmentation and thermal string models, on the pi ^{-} observables, mainly from light(er) ion beams at CERN SPS energies. The role of primary hadron rescattering (HadSc) is also discussed. We find that the PYTHIA 8.303/Angantyr model employing both pp-tuned and thermal-string model with HadSc is able to reproduce the observed pi ^{-} yields in the light(er) ion beams at the whole CERN SPS energies.
Highlights
The production mechanisms of hadrons from nucleusnucleus (AA) collisions may shed light on the formation of a new state of matter – the quark-gluon-plasma (QGP)
The code is incorporated in many microscopic transport models, such as UrQMD [5], HIJING [6], and AMPT [7], for generation of full exclusive events of AA-collisions and a e-mail: kamabdellatif@uqu.edu.sa frequently applied in comparisons to experimental data from NA61/SHINENA61 [8–12], STAR [13] and ALICE [14] collaborations. These event generators simulate the dynamics of hard and soft processes from high momentum transfer (Q ≥ 2 GeV), where perturbation theory is applicable, down to scales, where one must rely on string and hadronic models. It is demonstrated in Refs. [10,12] that the final multiplicities of π − in central 7Be + 9Be and 40Ar+45 Sc collisions are not reproduced by the well tested models of hadronization adopted in the Monte Carlo (MC) event generators such as UrQMD [5], HIJING [6] and AMPT [7]
Data on pion production are crucial for constraining basic properties of Monte Carlo event generators
Summary
The production mechanisms of hadrons from nucleusnucleus (AA) collisions may shed light on the formation of a new state of matter – the quark-gluon-plasma (QGP). It is conceived that a QGP can be partly formed in high multiplicity proton–proton (pp) reactions at the same energy per nucleon. Several features such as strangeness enhancement [1], formation of a ridge [2] and J/ suppression [3] are observed in both pp and central heavy-ion collisions, and have been interpreted as a QGP signature. The experimental facts raise the question of whether the description of π − high multiplicity in central light(er) is due to finding the right settings of hadronization models, or whether it requires invoking a QGP-like-state in MC generators.
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