Abstract
A search for the lepton-flavor violating decays B^{+}→K^{+}μ^{±}e^{∓} is performed using a sample of proton-proton collision data, collected with the LHCb experiment at center-of-mass energies of 7 and 8TeV and corresponding to an integrated luminosity of 3 fb^{-1}. No significant signal is observed, and upper limits on the branching fractions are set as B(B^{+}→K^{+}μ^{-}e^{+})<7.0(9.5)×10^{-9} and B(B^{+}→K^{+}μ^{+}e^{-})<6.4(8.8)×10^{-9} at 90% (95)% confidence level. The results improve the current best limits on these decays by more than one order of magnitude.
Highlights
Simulated samples are used to evaluate signal efficiencies, to train multivariate classifiers, to model the shape of the invariant mass of the Bþ → KþμÆe∓ signal candidates, and to study physics backgrounds
Background onlySignal model0 4500 m(K+μ−e+) [MeV/c2]0 4500 m(K+μ+e−) [MeV/c2] Observed Expected ± 1σ CLS ± 2σ B(B+→ K+μ−e+) B(B+→ K+μ+e−)BðBþ → Kþμ−eþÞ=10−9 BðBþ → Kþμþe−Þ=10−9
The simulated samples are adjusted using Bþ → KþJ=ψð→ μþμ−Þ and Bþ → KþJ=ψð→ eþe−Þ decays in data to correct data-simulation differences in the B-meson production kinematics, vertex quality, and detector occupancy represented by the number of tracks in the detector
Summary
Simulated samples are used to evaluate signal efficiencies, to train multivariate classifiers, to model the shape of the invariant mass of the Bþ → KþμÆe∓ signal candidates, and to study physics backgrounds. The simulated samples are adjusted using Bþ → KþJ=ψð→ μþμ−Þ and Bþ → KþJ=ψð→ eþe−Þ decays in data to correct data-simulation differences in the B-meson production kinematics, vertex quality, and detector occupancy represented by the number of tracks in the detector.
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