Enhanced Electromagnetic Corrections to the Rare Decay B_{s,d}→μ^{+}μ^{-}

Area of Science:

• Particle Physics
• Quantum Chromodynamics (QCD)
• Quantum Electrodynamics (QED)

Background:

• Rare B-meson leptonic decays (B_{s,d}→μ^{+}μ^{-}) are sensitive probes of new physics beyond the Standard Model.
• Previous theoretical analyses primarily focused on QCD effects, with electromagnetic corrections considered less significant.
• Understanding these decays requires precise calculations incorporating all relevant interactions at scales below the bottom-quark mass (m_{b}).

Purpose of the Study:

• To investigate electromagnetic corrections to rare B-meson leptonic decays, specifically B_{s,d}→μ^{+}μ^{-}.
• To identify and quantify novel effects arising from virtual photon exchange at scales below m_{b}.
• To update the Standard Model prediction for the branching ratio of B_{s}→μ^{+}μ^{-} incorporating these findings.

Main Methods:

• Analysis of electromagnetic corrections, focusing on virtual photon exchange effects.
• Investigation of B-meson structure probing through these interactions, leading to a 'nonlocal annihilation' effect.
• Calculation of the dynamical enhancement factor and its impact on the branching ratio.

Main Results:

• A novel 'nonlocal annihilation' effect due to virtual photon exchange was identified, probing B-meson structure.
• This effect provides a dynamical enhancement proportional to m_{b}/Λ_{QCD} and large logarithms.
• The impact on the branching ratio is approximately 1%, comparable to theoretical uncertainties and significantly larger than previous QED estimates.

Conclusions:

• Electromagnetic corrections introduce a significant, previously overlooked dynamical enhancement in rare B-meson leptonic decays.
• The updated Standard Model prediction for B(B_{s}→μ^{+}μ^{-})_{SM} is (3.57±0.17)×10^{-9}.
• This finding necessitates re-evaluation of theoretical uncertainties and interpretations of experimental results for these decays.