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Measurement of the running of the fine structure constant below 1 GeV with the KLOE detector
Ist Nazl Fis Nucl, Lab Nazl Frascati, Frascati, Italy.;Univ Messina, Dipartimento Sci Matemat & Informat, Sci Fis & Sci Terra, Messina, Italy..
Ist Nazl Fis Nucl, Lab Nazl Frascati, Frascati, Italy..
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2017 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 767, 485-492 p.Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV , 2017. Vol. 767, 485-492 p.
Keyword [en]
Vacuum polarization, arunning
National Category
Subatomic Physics
Identifiers
URN: urn:nbn:se:uu:diva-320023DOI: 10.1016/j.physletb.2016.12.016ISI: 000397861700074OAI: oai:DiVA.org:uu-320023DiVA: diva2:1088625
Funder
EU, FP7, Seventh Framework Programme, FP7-INFRASTRUCTURES2008-1 227431
Note

A KLOE-2 Collaboration

Available from: 2017-04-13 Created: 2017-04-13 Last updated: 2017-04-13Bibliographically approved

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Caldeira Balkeståhl, LiCao, BoHeijkenskjöld, LenaJohansson, TordKupsc, Andrzej
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