Dark photon and dark Z mediated B meson decays

Abstract

Abstract We study flavor changing neutral current decays of B and K mesons in the dark U(1) D model, with the dark photon/dark Z mass between 10 MeV and 2 GeV. Although the model provides an improved fit (compared to the standard model) to the differential decay distributions of B → K (∗) ℓ + ℓ −, with ℓ = μ, e, and B s → ϕμ + μ − , the allowed parameter space is ruled out by measurements of atomic parity violation, K + → μ + + invisible decay, and B s − B ¯ s $$ {B}_s-{\overline{B}}_s $$ mixing, among others. To evade constraints from low energy data, we extend the model to allow for (1) additional invisible Z D decay, (2) a direct vector coupling of Z D to muons, and (3) a direct coupling of Z D to both muons and electrons, with the electron coupling fine-tuned to cancel the Z D coupling to electrons via mixing. We find that only the latter case survives all constraints.

Keywords

• Bottom Quarks
• New Gauge Interactions
• New Light Particles
• Semi-Leptonic Decays