Transverse momentum of protons, pions and kaons in high multiplicity pp and pA collisions: Evidence for the color glass condensate?

Abstract

The CMS experiment at the Large Hadron Collider has recently presented data on the average transverse momentum of protons, kaons and pions as a function of particle multiplicity. We relate the particle multiplicity to saturation momentum using recently published computations of the interaction radius determined from the theory of the Color Glass Condensate. We show that the pp and the pA experimental data scale in terms of these saturation momenta. Computing transverse momentum spectra for identified particles using Boltzmann-type distributions and relating different associated multiplicities using geometric scaling, these simple distributions reproduce the observed dependence of the mean transverse momentum on particle multiplicities seen in both pp and pA interactions for pions to good accuracy, and to fair agreement for protons and kaons.

Geometrical scaling for energies available at the BNL Relativistic Heavy Ion Collider to those at the CERN Large Hadron Collider

“…The same value of α was used in Refs. [65,66]. These results seem to support the assumption that the global properties of the hadron production are determined by the properties of flux tubes of ∼1/ √ dN dy /S ⊥ size and are very little influenced by the size of the colliding system [18,65,67].…”

“…[65,66]. These results seem to support the assumption that the global properties of the hadron production are determined by the properties of flux tubes of ∼1/ √ dN dy /S ⊥ size and are very little influenced by the size of the colliding system [18,65,67]. A similar behavior was evidenced at the baryonic level at much lower energies, where the main features of the dynamic evolution of the fireball are determined by the initial baryon density profile and temperature and not too much by its size [68].…”

Ensemble meanptversus charged-hadron multiplicities in high energy nuclear collisions

“…Candidate mechanisms range from projectile nucleon dissociation and parton fragmentation to dijets [1][2][3][4] to color reconnection of multiple parton interactions [5], strong rescattering of partons and hadrons in a dense medium [6], hydrodynamic flows [7][8][9] or a colored-glass condensate [4,10], possibly including glasma flux tubes [11]. Recent high energy data from the LHC and the emergence of apparently novel effects in p-A or d-A collisions have further stimulated debate.…”

Saturation and geometrical scaling: from small x DIS to high energy heavy ion collisions

“…This behavior is indeed seen in the data. Furthermore correlations of p T with N ch are well described by GS supplemented with model calculations within Color Glass Condensate [15]. [18], STAR [19,20] and PHENIX [21,22] plotted as functions of p T .…”