Strangeness enhancement in the parton model

Some non-trivial features of the QCD-improved parton model relevant to applications on heavy particle production and semi-hard (small-x) processes of interest to collider physics are reviewed. The underlying ideas are illustrated by a simple example. Limitations of the naive parton formula as well as first order corrections and subtractions to it are dis-cussed in a quantitative way. The behavior of parton distribution functions at small x and for heavy quarks are discussed. Recent work on possible impact of unconventional small-x behavior of the parton distributions on small-x physics at SSC and Tevatron are summarized. The Drell-Yan process is found to be particularly sensitive to the small x dependence of parton distributions. Measurements of this process at the Tevatron can provide powerful constraints on the expected rates of semi-hard processes at the SSC.

Download Full-text

Particle production at RHIC and LHC energies

International Journal of Modern Physics A ◽

10.1142/s0217751x15501316 ◽

2015 ◽

Vol 30 (22) ◽

pp. 1550131 ◽

Cited By ~ 4

Author(s):

A. Tawfik ◽

E. Gamal ◽

A. G. Shalaby

Keyword(s):

Particle Production ◽

Hadron Collider ◽

Center Of Mass ◽

System Size ◽

Alice Experiment ◽

Center Of Mass Energy ◽

Particle Ratios ◽

Strangeness Enhancement ◽

Homogeneous Particle ◽

Energy Formula

The production of pion, kaon and proton was measured in Pb–Pb collisions at nucleus–nucleus center-of-mass energy [Formula: see text] by the ALICE experiment at Large Hadron Collider (LHC). The particle ratios of these species compared to the RHIC measurements are confronted to the hadron resonance gas (HRG) model and to simulations based on the event generators PYTHIA 6.4.21 and HIJING 1.36. It is found that the homogeneous particle–antiparticle ratios (same species) are fully reproducible by means of HRG and partly by PYTHIA 6.4.21 and HIJING 1.36. The mixed kaon–pion and proton–pion ratios measured at RHIC and LHC energies seem to be reproducible by the HRG model. On the other hand, the strange abundances are underestimated in both event generators. This might be originated to strangeness suppression in the event generators and/or possible strangeness enhancement in the experimental data. It is apparent that the values of kaon–pion ratios are not sensitive to the huge increase of [Formula: see text] from 200 (RHIC) to 2760 GeV (LHC). We conclude that the ratios of produced particle at LHC seem not depending on the system size.

Download Full-text