Test of lepton flavor universality in ; ; ; ; B; ; ±; ; ; →; ; K; ; ±; ; ; ; μ; +; ; ; μ; −; ; ; ; and ; ; ; ; B; ; ±; ; ; →; ; K; ; ±; ; ; ; e; +; ; ; e; Journal Article uri icon

Overview

abstract

  • 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.

publication date

  • July 1, 2024

has restriction

  • hybrid

Date in CU Experts

  • July 10, 2024 2:44 AM

Full Author List

  • CMS Collaboration T

author count

  • 1

Other Profiles

International Standard Serial Number (ISSN)

  • 0034-4885

Electronic International Standard Serial Number (EISSN)

  • 1361-6633

Additional Document Info

start page

  • 077802

end page

  • 077802

volume

  • 87

issue

  • 7