Transition between soft physics at the LHC and low-xphysics at HERA

Abstract

We find out the connection between the unintegrated gluon distribution at low intrinsic transverse momenta and the inclusive spectrum of the hadrons produced in pp collision at LHC energies in the mid-rapidity region and low hadron transverse momenta. The parameters of this distribution are found from the best description of the LHC data. Its application to the analysis of ep deep inelastic scattering allows us to obtain the results which describe reasonably well the H1 and ZEUS data on the structure functions at low x. A connection between the soft processes at LHC and small x physics at HERA has been found. PACS number(s): 12.38.-t, 13.85.-t

Significance of gluon density for soft and hard processes at LHC

“…In the present paper we continue our studies [1,2] and investigate the role of the non-perturbative input to the TMD gluon density in description of hard processes at the LHC. We improve the initial TMD gluon distribution proposed earlier to describe LHC data on the inclusive charged hadron spectra at higher transverse momenta 2.5 < p T < 4.5 GeV and numerically extend it to the whole kinematical region using the CCFM gluon evolution equation.…”

“…It is important that the third term in (2) is only non-zero at |k T | Λ QCD (1/x) δ with δ = α s N c . The details of the calculation and the relation between the TMD gluon density and the inclusive hadron spectra ρ h (y 0, p T ) ≡ E d 3 σ /d 3 p are given in our previous papers [1,2]. These spectra are presented as a sum of two parts [7,8]:…”

“…• Starting non-perturbative TMD gluon density The proposed early [1] non-perturbative gluon density is not able to describe the LHC data on the inclusive spectrum of charged hadrons at higher transverse momenta 2.5 < p T < 4.5 GeV even if additional pertubative QCD (pQCD) corrections [7,8] are taken into account at p T > 2 GeV. Moreover, gluon density (1) much faster decreases when k 2 T grows compared to the solution of the BFKL equation outside of the saturation region [5,6,9].…”

Development of the Baldin approach for the relativistic nuclear interactions

“…According to [7], [8] the inclusive cross-section of hadron production, taking into account the gluon contribution, can be written in the following form: Figure 1. Results of the calculations of the inclusive cross-section of pion production in pp collisions as a function of the transverse mass at the initial momenta P in = 31 GeV/c.…”

“…In figure 3 we present the calculations of inclusive spectra of charged hadrons (mainly pions and kaons) produced in pp collision at √ s = 7 TeV performed by using (12) and the perturbative QCD (PQCD) within the leading order (LO) [7,8] compared to the LHC data. Figure 3.…”