Test of lepton flavor universality in B ± → K ± μ + μ − and B ± → K ± e + e − decays in proton-proton collisions at s = 13 TeV

(CMS collaboration) Hayrapetyan, Aram; ..., ...; Giljanović, Duje; Godinović, Nikola; Lelas, Damir; Šćulac, Ana; Kovač, Marko; Šćulac, Toni; Bargassa, Pedrame; Brigljević, Vuko; Chitroda, Bhakti Kanulal; Ferenček, Dinko; Mishra, Saswat; Starodumov, Andrey; Šuša, Tatjana; ..., ...; Zhokin, Alexander (2024) Test of lepton flavor universality in B ± → K ± μ + μ − and B ± → K ± e + e − decays in proton-proton collisions at s = 13 TeV. Reports on progress in physics, 87 (7). ISSN 0034-4885

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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 , where q is 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 same q 2 range, B ( B ± → K ± μ + μ − ) = ( 12.42 ± 0.68 ) × 10 − 8 , is consistent with the present world-average value and has a comparable precision. © 2024 CERN, for the benefit of the CMS Collaboration.

Item Type:	Article
Uncontrolled Keywords:	High energy physics ; Experimental particle physics ; LHC ; CMS ; B physics ; lepton flavor universality ; B meson ; b to sll transitions ; p p: colliding beams ; lepton: flavor: universality ; p p: scattering ; B: semileptonic decay ; muon: pair production ; K ; B: branching ratio ; flavor: universality ; lepton: mass ; lepton: flavor ; branching ratio: ratio ; branching ratio: ratio: measured ; hadron: decay ; electron: pair production ; mass spectrum: (muon+ muon-)
Subjects:	NATURAL SCIENCES > Physics
Divisions:	Division of Experimental Physics
Depositing User:	Vuko Brigljević
Date Deposited:	15 Oct 2024 13:04
URI:	http://fulir.irb.hr/id/eprint/9167
DOI:	10.1088/1361-6633/ad4e65

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