A unified study of the production of all identified hadrons over wide ranges of transverse momenta at LHC

TL;DR

This paper models the production of all identified hadrons at LHC using a parton recombination approach, successfully reproducing transverse momentum spectra and highlighting the importance of minijets and parton conversion processes.

Contribution

It introduces a unified recombination model incorporating thermal and shower partons to describe hadron production across wide transverse momentum ranges at LHC.

Findings

Model reproduces LHC hadron spectra with few parameters.

Minijets significantly influence thermal parton enhancement.

Parton conversion occurs throughout medium expansion, challenging rapid equilibration assumptions.

Abstract

The production of all identified hadrons at the CERN Large Hadron Collider (LHC) is studied with emphasis on the $p_T$ distributions up to 20 GeV/c in central collisions at $\sqrt{s_{NN}}=2.76$ TeV. The parton recombination model is used to determine the hadronic \ppt\ spectra from the quark \dis s. From the heavy hyperon spectra it is known from earlier studies that the $u, d, s$ thermal \dis s in \ppt\ are exponential with large inverse slopes that cannot be identified with any temperature in conventional fluid models. They are used as inputs in our model together with shower partons determined from our treatment of momentum degradation that uses high-\ppt\ pion data as input. Those thermal and shower partons are used to calculate the $p_T$ \dis s of all observed hadrons ($\pi, K, p, \Lambda$, $\Xi$, $\Omega$ and $\phi$) over wide ranges of \ppt, so the system is highly constrained. We show how well the LHC data can be reproduced with only a few parameters to adjust. Centrality dependence has not been studied. What is learned is that minijets are important, not only in giving rise to abundant shower partons, but also in the conversion of semihard partons in the medium to soft partons that enhance the thermal partons. Since the conversion process can occur throughout the expansion phase of the high-density medium, this work provides the basis for questioning the validity of the assumption of rapid equilibration.