SEMINÁRIO DO GRUPO DE HÁDRONS E FÍSICA TEÓRICA - FEP
“Scheme variations of the QCD coupling and tau decays”
Diogo Boito, IFSC-USP
Dia: 11 de outubro, terça-feira, Edifício Principal, Ala 2, sala 335, IFUSP, às 17h.
Abstract:
Perturbation theory in successive powers of the coupling is most often an asymptotic expansion (at best). Different renormalisation schemes correspond to different asymptotic expansions to the same, scheme invariant, "true" result of the series. I will discuss a class of scheme transformations in QCD, parametrised by a single continuous parameter, that gives an extra handle on the perturbative series. The series can then be optimised in the spirit of asymptotic expansions in order to extract the best estimate from the few exactly known terms. The method can be applied to several processes such as Higgs decays into quark-antiquark and hadronic tau decays, and can have in impact in alpha_s extractions.
