Measurement of the running of the fine structure constant below 1 GeV with the KLOE detector

作者：Anastasi A; Babusci D; Bencivenni G; Berlowski M; Bloise C; Bossi F; Branchini R; Budano A; Balkestahl L Caldeira; Cao B; Ceradini F; Ciambrone R; Curciarello F; Czerwinski E; D'Agostini G; Dane E; De Leo V^*; De Lucia E; De Santis A; De Simone R; Di Cicco A; Di Domenico A; Di Salvo R; Domenici D; D'Uffizi A; Fantini A; Felici G; Fiore S; Gajos A; Gauzzi R; Giardina G; Giovannella S; Graziani E; Happacher F; Heijkenskjold L

来源：Physics Letters B, 2017, 767: 485-492.

DOI：10.1016/j.physletb.2016.12.016

• Vacuum polarization
• arunning

We have measured the running of the effective QED coupling constant alpha(s) in the time-like region 0.6 < root s < 0.975 GeV with the KLOE detector at DA Phi NE using the Initial-State Radiation process e(+) e(-) -> mu(+) mu(-)gamma. It represents the first measurement of the running of alpha(s) in this energy region. Our results show a more than 5 sigma significance of the hadronic contribution to the running of alpha(s), which is the strongest direct evidence both in time- and space-like regions achieved in a single measurement. By using the e(+) e(-) -> pi(+) pi(-) cross section measured by KLOE, the real and imaginary parts of the shift Delta alpha(s) have been extracted. From a fit of the real part of Delta alpha(s) and assuming the lepton universality the branching ratio BR(omega -> mu(+) mu(-)) = (6.6 +/- 1.4(stat) +/- 1.7(syst)) (.) 10 (5)has been determined.

• 出版日期2017-4-10