Soft gluon radiation and energy dependence of total hadronic cross sections

Abstract

An impact parameter representation for soft gluon radiation is applied to obtain both the initial decrease of the total cross-section (σ tot ) for proton-proton collisions as well as the later rise of σ tot with energy for both pp and pp. The non-perturbative soft part of the eikonal includes only limited low energy gluon emission and leads to the initial decrease in the proton-proton cross-section. On the other hand, the rapid rise in the hard, perturbative jet part of the eikonal is tamed into the experimentally observed mild increase by soft gluon radiation whose maximum energy rises slowly with energy.

Aspects of a dynamical gluon mass approach to elastic hadron scattering at LHC

“…Despite its efficiency in the analysis we have developed, it may be important to study the effects of different parton density functions, along the lines that have been discussed by Achilli et al [43]. In this class of QCD-based models, the attenuation in the rise of the total cross sections comes from soft gluon emission from colliding partons [5,6,7]. These emissions affect the matter distribution and the resulting overlap function can be calculated from the soft gluon transverse-momentum resummed distribution.…”

“…With this aim (see also [5,6,7]), a novel interpretation for some fundamental parameters in eikonalized QCD-inspired models has been previously proposed, allowing a quantitative connection between elastic hadron scattering data and the nonperturbative regime [8,9,10]. This Dynamical Gluon Mass (DGM) approach is based on the possibility that the nonperturbative dynamics of QCD generates an effective gluon mass at the small momentum transfer region, which is strongly supported by recent QCD lattice simulations [11], as well as by other phenomenological results [12,13,14].…”

Modeling pion and proton total cross-sections at LHC

“…(7), the coefficients A i and the exponents α i are in principle different for each different process. Following our analyses in [25,26], we chose the set of high energy parameters given by GRV densities and set {1,5,4} [27], p tmin = 1.15 GeV and p = 0.75. We then applied Eqs.…”

p – airproduction cross-section and uncorrelated mini-jets processes in pp-scattering

“…In this paper we describe proton − air production cross-section up to the recent AUGER measurement [9], using the inelastic pp cross-section obtained from a QCD mini-jet model with soft gluon re-summation [10,11].…”

“…Thus the nuclear density seen by the incoming protons will only be proportional to A 2/3 for the soft collisions, and to A for the hard part. (ii) For interactions with transverse momenta p t (1 ÷ 2) GeV, we shall employ QCD effects in the form of mini-jets and soft gluon emission as in the model developed in [10,11,13].…”