Forward hadron productions in high energyppcollisions from a Monte-Carlo generator for color glass condensate

Abstract

We develop a Monte-Carlo event generator based on combination of a parton production formula including the effects of parton saturation (called the DHJ formula) and hadronization process due to the Lund string fragmentation model. This event generator is designed for the description of hadron productions at forward rapidities and in a wide transverse momentum range in high-energy proton-proton collisions. We analyze transverse momentum spectra of charged hadrons as well as identified particles; pion, kaon, (anti-)proton at RHIC energy, and ultra-forward neutral pion spectra from LHCf experiment. We compare our results to those obtained in other models based on parton-hadron duality and fragmentation functions.PACS numbers: 24.85.+p,12.38.Mh

Ultraforward particle production from color glass condensate and Lund fragmentation

“…3 where we plot the distribution of Bjorken-x values contributing to these collisions from the projectile and target respectively. They are peaked in x proj ≈ 0.1 and x targ ≈ 10 −8 , which indicates a much stronger dilute-dense asymmetry than in the RHIC case, Similarly to the previous analysis presented in [15], we obtain a very good description of p-p data for all rapidities, see Fig. 4.…”

“…1. These fits act as a reference for calibration, as the datasets used have been largely studied in previous works based on the DHJ formula [11,15,43]. We build the PDF of the deuteron from the proton PDFs assuming strict isospin symmetry.…”

Saturation and forward jets in proton-lead collisions at the LHC

“…Refs. [90,91] where the Lund string model based Monte Carlo methods were used to describe the fragmentation processes. A more realistic production mechanism for the jet formation would also motivate to use a more realistic jet finding algorithm to distinguish jets that are merged from the other jets whose energy is not included in the total energy of the observed jet.…”

Mass Ordering of Spectra from Fragmentation of Saturated Gluon States in High-Multiplicity Proton-Proton Collisions

“…In this letter, we will introduce a CGC+Lund model that provides a mechanism to fragment gluons emerging from the Glasma into various hadron species and apply the model to address the question whether the aforementioned mass-splitting patterns can be reproduced in an initial state framework. We note that there have been previous merging of CGC based models in k T factorization frameworks [41,42] to string fragmentation. However, our approach is the first fully dynamical one, combining the IP-Glasma model of event-by-event Yang-Mills evolution of primordial color charge fluctuations [43,44], with the state-of-the-art Lund string fragmentation algorithm [45,46] of the PYTHIA event generator [47].…”

“…These computations were thus unable to address the par-ticle species dependence of the average transverse momentum p T as a function of multiplicity and that of the Fourier harmonic v 2 (p T ) in high multiplicity events -the observed mass-splitting patterns of both these quantities were previously adduced as strong evidence of hydrodynamic flow [40].In this letter, we will introduce a CGC+Lund model that provides a mechanism to fragment gluons emerging from the Glasma into various hadron species and apply the model to address the question whether the aforementioned mass-splitting patterns can be reproduced in an initial state framework. We note that there have been previous merging of CGC based models in k T factorization frameworks [41,42] to string fragmentation. However, our approach is the first fully dynamical one, combining the IP-Glasma model of event-by-event Yang-Mills evolution of primordial color charge fluctuations [43,44], with the state-of-the-art Lund string fragmentation algorithm [45,46] of the PYTHIA event generator [47].…”