Tests of Lepton Universality Using B^{0}→K_{S}^{0}ℓ^{+}ℓ^{-} and B^{+}→K^{*+}ℓ^{+}ℓ^{-} Decays

Area of Science:

• High Energy Physics
• Particle Physics
• Quantum Chromodynamics

Background:

• Lepton universality is a key principle of the Standard Model, predicting that fundamental particles called leptons interact similarly.
• Deviations from lepton universality in B meson decays could indicate new physics beyond the Standard Model.
• Previous experiments have shown tensions in lepton universality tests, motivating further investigation.

Purpose of the Study:

• To test lepton universality by comparing the decay rates of B mesons into final states involving electrons versus muons.
• To measure the differential branching fractions for B0→KS0e+e- and B+→K*+e+e- decays as a function of dilepton invariant mass squared.
• To report the first observation of B0→KS0e+e- and B+→K*+e+e- decays.

Main Methods:

• Utilizing proton-proton collision data from the LHCb experiment, corresponding to an integrated luminosity of 9 fb^{-1}.
• Analyzing B^{0}→K_{S}^{0}ℓ^{+}ℓ^{-} and B^{+}→K^{*+}ℓ^{+}ℓ^{-} decays, where ℓ represents either an electron or a muon.
• Measuring differential branching fractions in intervals of the dilepton invariant mass squared.

Main Results:

• The measured differential branching fractions for B^{0}→K_{S}^{0}e^{+}e^{-} and B^{+}→K^{*+}e^{+}e^{-} decays are consistent with the Standard Model predictions.
• The results are in agreement with previous tests of lepton universality in related B meson decay modes.
• The first observation of the B^{0}→K_{S}^{0}e^{+}e^{-} and B^{+}→K^{*+}e^{+}e^{-} decays is reported.

Conclusions:

• The study provides strong evidence supporting lepton universality in the investigated B meson decays.
• The findings contribute to the ongoing effort to precisely test the Standard Model and search for new physics phenomena.
• The first observation of these decays enhances the experimental toolkit for future precision measurements.