Search for the dark photon in B 0 → A′A′, A′ → e + e ?, μ + μ ?, and π + π ? decays at Belle
Journal
Journal of High Energy Physics
Journal Volume
2021
Journal Issue
4
Date Issued
2021
Author(s)
Abstract
We present a search for the dark photon A′ in the B0 → A′A′ decays, where A′ subsequently decays to e+e?, μ+μ?, and π+π?. The search is performed by analyzing 772 × 106BB¯ events collected by the Belle detector at the KEKB e+e? energy-asymmetric collider at the ?(4S) resonance. No signal is found in the dark photon mass range 0.01 GeV/c2 ? mA′ ? 2.62 GeV/c2, and we set upper limits of the branching fraction of B0 → A′A′ at the 90% confidence level. The products of branching fractions, ?(B0→A′A′)×?(A′→e+e?)2 and ?(B0→A′A′)×?(A′→μ+μ?)2, have limits of the order of 10?8 depending on the A′ mass. Furthermore, considering A′ decay rate to each pair of charged particles, the upper limits of ? (B→ A′ A′) are of the order of 10?8–10?5. From the upper limits of ? (B→ A′ A′) , we obtain the Higgs portal coupling for each assumed dark photon and dark Higgs mass. The Higgs portal couplings are of the order of 10?2–10?1 at mh′?mB0 ± 40 MeV/c2 and 10?1–1 at mh′?mB0 ± 3 GeV/c2. [Figure not available: see fulltext.] ? 2021, The Author(s).
Subjects
B physics; Beyond Standard Model; e+-e- Experiments; Rare decay;
Type
journal article