Determination of fragmentation functions and their application to exotic-hadron search

TL;DR

This paper determines fragmentation functions for various hadrons using global data analyses and explores their application in identifying the internal structure of exotic hadrons like f_0(980), highlighting uncertainties and improvements from NLO calculations.

Contribution

It provides the first comprehensive determination of fragmentation functions for pion, kaon, and proton at LO and NLO, and proposes a novel method to study exotic-hadron internal structures.

Findings

Fragmentation functions are well determined for favored quarks but uncertain for disfavored quarks and gluons.

NLO analysis reduces uncertainties compared to LO.

Using fragmentation differences to probe exotic-hadron structure faces large uncertainties.

Abstract

We discuss studies on determination of fragmentation functions and an application to exotic-hadron search by using characteristic differences between favored and disfavored functions. The optimum fragmentation functions are determined for pion, kaon, and proton in the leading order (LO) and next-to-leading order (NLO) of the running coupling constant alpha_s by global analyses of hadron-production data in electron-positron annihilation. Various parametrization results are much different in disfavored-quark and gluon fragmentation functions; however, we show that they are within uncertainties of the determined functions by using the Hessian method for uncertainty estimation. We find that the uncertainties are especially large in the disfavored-quark and gluon fragmentation functions. NLO improvements are explicitly shown in the determination by comparing uncertainties of the LO and NLO functions. Next, we propose to use differences between favored and disfavored fragmentation functions for determining internal quark configurations of exotic hadrons. We make a global analysis for f_0 (980) for finding its internal configuration; however, uncertainties are too large to specify the structure at this stage.