Magnetic-dipole corrections to RK and RK in the Standard Model and dark photon scenarios

A bstract In this work we evaluate the long-distance QED contributions, induced by the magnetic-dipole corrections to the final charged leptons, on the B meson decay widths B → ( K, K* ) ℓ + ℓ − and ratios R K,K* = Γ( B → ( K, K* ) μ + μ − )/Γ( B → ( K, K* ) e + e − ), as well as on R K , K ∗ τ (wit...

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Published in:The journal of high energy physics 2020-10, Vol.2020 (10), Article 145
Main Authors: Gabrielli, Emidio, Palmiotto, Marco
Format: Article
Language:English
Subjects:
Anomalies
Classical and Quantum Gravitation
Coulomb potential
Dipole interactions
Elementary Particles
Flavor (particle physics)
High energy physics
Leptons
Particle decay
Photons
Physics
Physics and Astronomy
Quantum Field Theories
Quantum Field Theory
Quantum Physics
Regular Article - Theoretical Physics
Relativity Theory
Standard model (particle physics)
String Theory
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Summary:A bstract In this work we evaluate the long-distance QED contributions, induced by the magnetic-dipole corrections to the final charged leptons, on the B meson decay widths B → ( K, K* ) ℓ + ℓ − and ratios R K,K* = Γ( B → ( K, K* ) μ + μ − )/Γ( B → ( K, K* ) e + e − ), as well as on R K , K ∗ τ (with μ replaced by the τ lepton). QED long-distance contributions induced by the Coulomb potential corrections (Fermi-Sommerfeld factors) were also included. Corresponding corrections to the inclusive decay widths of B → X s ℓ + ℓ − , with ℓ = e, μ, τ , are also analyzed for completeness. The magnetic-dipole corrections, which are manifestly Lepton Flavor Universality violating and gauge-invariant, are expected to be particularly enhanced in R K* for the dilepton mass region close to the threshold. However, we find that the largest contribution of all these corrections to the R K,K * observables do not exceed a few per mille effect, thus reinforcing the validity of previous estimates about the leading QED corrections to R K,K* . Finally, viable new physics contributions to R K,K* induced by the exchange of a massless dark-photon via magnetic-dipole interactions, which provide the leading contribution to the corresponding B → ( K, K* ) ℓ + ℓ − amplitudes in this scenario, are analyzed in light of the present R K,K* anomalies.
ISSN:1029-8479
1029-8479
DOI:10.1007/JHEP10(2020)145