Transverse momentum dependent parton densities in a proton from the generalized DAS approach

TL;DR

This paper derives analytical expressions for transverse momentum dependent parton densities in a proton using a Bessel-inspired small-x behavior within the DAS approach, and applies them to LHC phenomenology.

Contribution

It introduces a novel analytical method for calculating TMD parton densities based on the DAS approach and KMR prescription, with phenomenological applications to LHC processes.

Findings

Analytical expressions for TMD parton densities at small x.

Comparison of different kinematical constraint implementations.

Application to LHC process predictions.

Abstract

We use the Bessel-inspired behavior of parton densities at small Bjorken $x$ values, obtained in the case of the flat initial conditions for DGLAP evolution equations in the double scaling QCD approximation (DAS), to evaluate the transverse momentum dependent (TMD, or unintegrated) quark and gluon distribution functions in a proton. The calculations are performed analytically using the Kimber-Martin-Ryskin (KMR) prescription with different implementation of kinematical constraint, reflecting the angular and strong ordering conditions. The relations between the differential and integral formulation of the KMR approach is discussed. Several phenomenological applications of the proposed TMD parton densities to the LHC processes are given.