Test of lepton flavor universality in B → Kℓ+ decays

Belle Collaboration

Research output: Contribution to journalArticlepeer-review

Abstract

We present measurements of the branching fractions for the decays B → Kµ+µ and B → Ke+e, and their ratio (RK), using a data sample of 711 fb−1 that contains 772 × 106 BB¯ events. The data were collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e collider. The ratio RK is measured in four bins of dilepton invariant-mass squared, q2; the results are RK = {001 0 .... 989511 81 +0+0+0+0− − 000 0........ 27272928 2423 26 23 ±±± ± 000 0 .... 060607 05 qqq q2222>(1(0 (4 14... . 01 0 18, 46 8 ... 0)0) 12) GeV GeVGeV2 GeV /c422/c/c.2/c 44,4, The first uncertainties listed are statistical, and the second uncertainties are systematic. The RK value in the whole q2 range is found to be 1.06 +0−0..1514 ± 0.07. We also measure CP−averaged isospin asymmetries in the same q2 bins; the results are consistent with a null asymmetry with the largest difference of 2.7 standard deviations is found in the q2 ∈ (1.0, 6.0) GeV2/c4 bin in the mode with muon final states. The measured branching fractions are B(B → Kµ+µ) = (5.5±0.5±0.3)×107 and B(B → Ke+e) = (5.1 ± 0.5 ± 0.3) × 10−7. These results are compatible with standard model expectations.

Original languageEnglish
JournalUnknown Journal
Publication statusPublished - Aug 5 2019
Externally publishedYes

ASJC Scopus subject areas

  • General

Fingerprint Dive into the research topics of 'Test of lepton flavor universality in B → Kℓ<sup>+</sup>ℓ<sup>−</sup> decays'. Together they form a unique fingerprint.

Cite this