Towards the NNLO evolution of polarised parton distributions
| Autor: | Vogt, A., Moch, S., Rogal, M., Vermaseren, J. A. M. |
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| Rok vydání: | 2008 |
| Předmět: | |
| Zdroj: | Nucl.Phys.Proc.Suppl.183:155-161,2008 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1016/j.nuclphysbps.2008.09.097 |
| Popis: | We report on the first calculation of the structure function g_1 in polarised deep-inelastic scattering to the third order in massless perturbative QCD. The calculation follows the dispersive approach already used for the corresponding unpolarised cases of F_2,L, but additionally involves higher tensor integrals and the Dirac matrix gamma_5 in D unequal 4 dimensions. Our results confirm all known two-loop expressions including the coefficient functions of Zijlstra and van Neerven not independently verified before. At three loops we extract the helicity-difference next-to-next-to-leading order (NNLO) quark-quark and gluon-quark splitting functions Delta P_qq and Delta P_qg. The results exhibit interesting features concerning sum rules and the momentum-fraction limits x to 1 and x to 0. Comment: 7 pages, LaTeX, 4 ps/eps-figures. Contribution to the proceedings of the workshops `Loops and Legs in Quantum Field Theory', April 2008, Sondershausen (Germany) and (shortened) DIS 2008, London, April 2008 |
| Databáze: | arXiv |
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