Implementing consistent NLO factorization in single inclusive forward hadron production

TL;DR

This paper addresses the issue of negative cross sections in NLO calculations of forward hadron production by proposing a new formulation that yields physically consistent results at high transverse momenta, highlighting ongoing challenges with running coupling effects.

Contribution

The paper introduces a new formulation for NLO factorization in forward hadron production that remains physical at large transverse momenta, improving upon previous problematic results.

Findings

The new formulation produces positive cross sections at high transverse momenta.

Fixed coupling calculations are consistent with physical expectations.

Incorporating running coupling effects remains a challenge.

Abstract

Single inclusive forward hadron production in high-energy hadron collisions can provide an important test of the Color Glass Condensate picture at small $x$. Recent studies of this process at next-to-leading order have led to problematic results, with cross sections becoming negative at large transverse momenta. We study a new formulation of this quantity proposed recently by Iancu et al. We show that it leads to physical results up to large transverse momenta at fixed coupling. Taking into account running coupling effects in a way that is consistent with existing DIS calculations still poses a challenge.