Investigating the inclusive transverse spectra in high-energy pp collisions in the context of geometric scaling framework

L S Moriggi,G M Peccini,M V T Machado

doi:10.1103/physrevd.102.034016

Abstract

The presence of geometric scaling within the $p_T$ spectra of produced hadrons at high energy $pp$ collisions using small-$x$ $k_T$-factorization is investigated. It is proposed a phenomenological parameterization for the unintegrated gluon distribution in the scaling range which reproduces the features of the differential cross section both in the saturated and dilute perturbative QCD regimes. As the saturation scale acts as an effective regulator of the infrared region (IR), the extension of the model to quantities usually associated to soft physics is studied. The approach is applied to compute the average $p_T$ and the rapidity distribution of produced gluons at high energies.

Highlights

The transverse momentum spectra of produced hadrons in ppðp Þ collisions is an observable that has been analyzed in different experiments, from fixed target ones at low energies up to LHC energies
The presence of a typical momentum scale that determines the growth of the cross section at high energies and at small pT is predicted within the saturation/Color Glass Condensate (CGC) framework, i.e., the saturation scale QsðxÞ
Our procedure consists of fitting δn from a total cross section of Deep Inelastic Scattering (DIS) within the scaling domain and looking into how compatible it will be with the pT spectra of hadrons

Summary

INTRODUCTION

The transverse momentum spectra of produced hadrons in ppðp Þ collisions is an observable that has been analyzed in different experiments, from fixed target ones at low energies up to LHC energies. The presence of a typical momentum scale that determines the growth of the cross section at high energies and at small pT is predicted within the saturation/Color Glass Condensate (CGC) framework, i.e., the saturation scale QsðxÞ This quantity establishes the region in which the gluon distribution has its maximum value, resulting in a slower growth of the cross section above that limit. This behavior emerges in the data through the geometric scaling on the variable τ 1⁄4 Q2=Q2sðxÞ, indicating that the cross section does not depend separately on Q2 and x but rather on the ratio between the momentum and saturation scales. IV we summarize the main points and results and expose our conclusions

THEORETICAL FRAMEWORK AND MAIN PREDICTIONS

RESULTS AND DISCUSSIONS

SUMMARY AND CONCLUSIONS