Year: 2026
Type: article
Abstract: A bstract Within the framework of nonrelativistic quantum chromodynamics (NRQCD) factorization, we compute the $$ \mathcal{O}\left({v}^4\right) $$ O v 4 relativistic corrections to the fragmentation of a heavy quark into the color-singlet $$ {}^1{S}_0^{\left[1\right]} $$ S 0 1 1 and $$ {}^3{S}_1^{\left[1\right]} $$ S 1 1 3 quarkonium states. Using the Collins-Soper definition of the fragmentation function, we reproduce the known $$ \mathcal{O}\left({v}^2\right) $$ O v 2 results. We find that the $$ \mathcal{O}\left({v}^4\right) $$ O v 4 correction gives a positive contribution relative to the leading order result over a wide range of the light-cone momentum fraction z , while its magnitude remains much smaller than that of the $$ \mathcal{O}\left({v}^2\right) $$ O v 2 correction. This behavior indicates a good convergence of the NRQCD relativistic expansion in this process. We further extend the calculation to the fragmentation functions in the unequal-mass case at $$ \mathcal{O}\left({v}^4\right) $$ O v 4 and obtain the corresponding analytical expressions.
Source: Journal of High Energy Physics
Authors: Sai Cui, Yi-Jie Li, Guang-Zhi Xu, Kui-Yong Liu
Institutions: Liaoning University, Liaoning Normal University
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: diamond
Awards: G2393065093, G606306160
OpenAlex ID: W7135203107