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Title: Test of lepton flavor universality in B±→K±μ+μ− and B±→K±e+e− decays in proton-proton collisions at s=13TeV
Abstract A test of lepton flavor universality in B ± K ± μ + μ and B ± K ± e + e decays, as well as a measurement of differential and integrated branching fractions of a nonresonant B ± K ± μ + μ decay are presented. The analysis is made possible by a dedicated data set of proton-proton collisions at s = 13 TeV recorded in 2018, by the CMS experiment at the LHC, using a special high-rate data stream designed for collecting about 10 billion unbiased b hadron decays. The ratio of the branching fractions B ( B ± K ± μ + μ ) to B ( B ± K ± e + e ) is determined from the measured double ratio R ( K ) of these decays to the respective branching fractions of the B ± J / ψ K ± with J / ψ μ + μ and e + e decays, which allow for significant cancellation of systematic uncertainties. The ratio R ( K ) is measured in the range 1.1 < q 2 < 6.0 GeV 2 , whereqis the invariant mass of the lepton pair, and is found to be R ( K ) = 0.78 0.23 + 0.47 , in agreement with the standard model expectation R ( K ) 1 . This measurement is limited by the statistical precision of the electron channel. The integrated branching fraction in the sameq2range, B ( B ± K ± μ + μ ) = ( 12.42 ± 0.68 ) × 10 8 , is consistent with the present world-average value and has a comparable precision.  more » « less
Award ID(s):
2121686
PAR ID:
10521896
Author(s) / Creator(s):
Publisher / Repository:
IOP Publishing
Date Published:
Journal Name:
Reports on Progress in Physics
Volume:
87
Issue:
7
ISSN:
0034-4885
Format(s):
Medium: X Size: Article No. 077802
Size(s):
Article No. 077802
Sponsoring Org:
National Science Foundation
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