Recent developments on parton-to-photon fragmentation functions

TL;DR

This paper reviews recent progress in understanding parton-to-photon fragmentation functions, highlighting theoretical models, comparing existing sets, and emphasizing the potential of semi-inclusive processes to improve experimental constraints.

Contribution

It summarizes key theoretical concepts, compares available fragmentation function sets, and advocates for semi-inclusive processes as promising avenues for future research.

Findings

Semi-inclusive $pp\to(\text{jet}\gamma)X$ process offers better sensitivity to fragmentation functions.

Current $pp\to\gamma X$ process has limited sensitivity to fragmentation contributions.

Comparison of different fragmentation function sets reveals discrepancies and areas for improvement.

Abstract

We report on some recent developments concerning parton-to-photon fragmentation functions. We briefly summarize the main theoretical concepts on which the currently available extractions of these fragmentation functions rely: evolution and the vector meson dominance model. We present comparisons of the available sets. We argue that the single-inclusive photon production process $pp\to\gamma X$ possesses only little sensitivity to the fragmentation contribution. Instead, the semi-inclusive process $pp\to(\text{jet}\,\gamma)X$, for which the photon is observed inside a fully reconstructed jet and is part of the jet, is shown to offer much potential for providing valuable new information.