| Full text | |
| Author(s): |
Boito, Diogo
;
Golterman, Maarten
;
Maltman, Kim
;
Peris, Santiago
Total Authors: 4
|
| Document type: | Journal article |
| Source: | PHYSICAL REVIEW D; v. 95, n. 3, p. 19-pg., 2017-02-22. |
| Abstract | |
Several different analysis methods have been developed to determine the strong coupling via finite-energy sum-rule analyses of hadronic tau decay data. While most methods agree on the existence of the well-known ambiguity in the choice of a resummation scheme due to the slow convergence of QCD perturbation theory at the tau mass, there is an ongoing controversy over how to deal properly with nonperturbative effects. These are small, but not negligible, and include quark-hadron "duality violations" (i.e., resonance effects) which are not described by the operator product expansion ( OPE). In one approach, an attempt is made to suppress duality violations enough that they might become negligible. The number of OPE parameters to be fit, however, then exceeds the number of available sum rules, necessitating an uncontrolled OPE truncation, in which a number of higher-dimension OPE contributions in general present in QCD are set to zero by hand. In the second approach, truncation of the OPE is avoided by construction, and duality violations are taken into account explicitly, using a physically motivated model. In this article, we provide a critical appraisal of a recent analysis employing the first approach and demonstrate that it fails to properly account for nonperturbative effects, making the resulting determination of the strong coupling unreliable. The second approach, in contrast, passes all self-consistency tests, and provides a competitive determination of the strong coupling from tau decays. (AU) | |
| FAPESP's process: | 15/20689-9 - Precise determination of fundamental QCD parameters |
| Grantee: | Diogo Rodrigues Boito |
| Support Opportunities: | Research Grants - Young Investigators Grants |