Higher-order relativistic corrections to gluon fragmentation into spin-triplet S-wave quarkonium

• DOI: 10.1007/jhep11(2012)020
• Publication Date: 2012-11-07T03:58:04Z
• Authors: Geoffrey T. Bodwin; U-Rae Kim; Jungil Lee
• Keywords: Fragmentation

We compute the relative-order-v^4 contribution to gluon fragmentation into quarkonium in the 3S1 color-singlet channel, using the nonrelativistic QCD (NRQCD) factorization approach. The QCD fragmentation process contains infrared divergences that produce single and double poles in epsilon in 4-2epsilon dimensions. We devise subtractions that isolate the pole contributions, which ultimately are absorbed into long-distance NRQCD matrix elements in the NRQCD matching procedure. The matching procedure involves two-loop renormalizations of the NRQCD operators. The subtractions are integrated over the phase space analytically in 4-2epsilon dimensions, and the remainder is integrated over the phase-space numerically. We find that the order-v^4 contribution is enhanced relative to the order-v^0 contribution. However, the order-v^4 contribution is not important numerically at the current level of precision of quarkonium-hadroproduction phenomenology. We also estimate the contribution to hadroproduction from gluon fragmentation into quarkonium in the 3PJ color-octet channel and find that it is significant in comparison to the complete next-to-leading-order-in-alpha_s contribution in that channel.<br/>41 pages, 8 figures, 3 tables, minor corrections, version published in JHEP. Eq. (6.3) corrected. Incorporates erratum JHEP 07 (2023) 170 to JHEP 11 (2012) 020<br/>