Jet lag effect and leading hadron production

TL;DR

This paper introduces the concept of jet lag, a phenomenon where higher quark Fock states cause energy loss and slow down quark jets, leading to a flatter fragmentation function that aligns well with experimental data.

Contribution

It presents a novel explanation for the steeply falling fragmentation function by incorporating jet lag effects, improving agreement with observations.

Findings

Higher quark Fock states slow down the quark jet.

Jet lag effect flattens the fragmentation function.

Good agreement with experimental data achieved.

Abstract

We propose a solution for the long standing puzzle of a too steeply falling fragmentation function for a quark fragmenting into a pion, calculated by Berger [1] in the Born approximation. Contrary to the simple anticipation that gluon resummation worsens the problem, we find good agreement with data. Higher quark Fock states slow down the quark, an effect which we call jet lag. It can be also expressed in terms of vacuum energy loss. As a result, the space-time development of the jet shrinks and the $z$-dependence becomes flatter than in the Born approximation. The space-time pattern is also of great importance for in-medium hadronization.