The increase with energy of the parton transverse momenta in the current fragmentation region and related pQCD phenomena in DIS at very high energies

TL;DR

This paper investigates how parton transverse momenta in the current fragmentation region grow rapidly with energy in high-energy DIS within the pQCD dipole model, revealing new phenomena and implications for LHC proton-proton collisions.

Contribution

It introduces a detailed analysis of energy-dependent parton momentum scales in DIS and derives a modified Gribov formula within the black disc regime, highlighting new pQCD phenomena at very high energies.

Findings

Parton transverse momenta increase rapidly with energy in DIS.

The coherence length grows as s^{0.6}, slower than traditional models.

Gluon densities in the black disc regime do not decrease with energy.

Abstract

We find, within the pQCD dipole model for DIS processes, a rapid increase with energy of the scale of parton momenta in the current fragmentation region in the limit $s\to \infty$ and fixed $Q^2$ . We explain the equivalence between the dispersion representation over $Q^2$ for LT pQCD zero angle amplitude of $\gamma^*+T\to \gamma^*+T$ scattering at large energies and the $k_t$ factorization, and use it to evaluate the scales of the hard processes in the current fragmentation region. We derive within the black disc (BD) regime the modified Gribov formula for the total cross-section of the DIS. We evaluate the coherence length of the processes relevant for the BD regime and find that it increases with energy as $\sim s^{0.6}$ i.e. significantly slower than in the parton model ($1/2m_Nx$ - the Ioffe length) as well as in pQCD. In the BD regime we estimate the gluon densities, local in the coordinate space, and find that they do not decrease with the energy. We discuss briefly how the new pQCD phenomena may reveal itself in the proton-proton collisions at LHC