Test of lepton universality using b+ → K+ℓ+ℓ- decays.

By R. Aaij, B. Adeva, M. Adinolfi, A. Affolder, Z. Ajaltouni, S. Akar, J. Albrecht, F. Alessio, M. Alexander, S. Ali and 489 more. Physical Review Letters, 2014

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A measurement of the ratio of the branching fractions of the B(+) → K(+)μ(+)μ(-) and B(+) → K(+)e(+)e(-) decays is presented using proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb(-1), recorded with the LHCb experiment at center-of-mass energies of 7 and 8 TeV. The value of the ratio of branching fractions for the dilepton invariant mass squared range 1 < q(2) < 6 GeV(2)/c(4) is measured to be 0.745(-0.074)(+0.090)(stat) ± 0.036(syst). This value is the most precise measurement of the ratio of branching fractions to date and is compatible with the standard model prediction within 2.6 standard deviations.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/68f24163b9ecadedbd329351cf247050aa68000f

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Citations in the corpus

Λ b →Λ ℓ + ℓ - form factors, differential branching fraction, and angular observables from lattice QCD with relativistic b quarks (2016, neutral): “Some tensions between the experimental data and calculations in the Standard Model have been found, including in the B → K∗(→ K π)μ+μ− angular distribution [2–4], the B → K(∗)μ+μ− and Bs → φμ+μ− differential decay rates [5–11], and the ratio RK of B → Kμ+μ− and B → Ke+e− decay rates [12].”
Charged Lepton Flavour Violation: An Experimental and Theoretical Introduction (2017, background): “[211] R. Aaij et al. [LHCb Collaboration], “Angular analysis of the B0 → K∗0µ+µ− decay using 3 fb−1 of integrated luminosity,” JHEP 1602 (2016) 104 [arXiv:1512.04442 [hep-ex]].”
New physics in b → s μ + μ − after the measurement of R K * (2017, neutral): “These results are similar to that of the LHCb measurement of RK ≡ B(B → K+μ+μ−)/B(B+ → K+e+e−) [4]: R K = 0.”
On the anomalies in the latest LHCb data (2016, background): “6σ deviation from the SM prediction [35] what might signal a first sign of lepton non-universality.”
New Physics in $${\varvec{b \rightarrow s \ell ^+ \ell ^-}}$$ confronts new data on lepton universality (2019, methodology): “Several hints in favour of LFUV have surfaced in the past few years in experimental searches at LHCb [41,42] and Belle [14].”