Observation of the decay D0→ρ−μ+νμ

Abstract

By analyzing an e+e− annihilation data sample corresponding to an integrated luminosity of 2.93 fb−1 collected at a center-of-mass energy of 3.773 GeV with the BESIII detector, we measure the branching fraction of the D0→ρ−μ+νμ decay for the first time. We obtain BD0→ρ−μ+νμ=(1.35±0.09stat±0.09syst)×10−3. Using the world average of BD0→ρ−e+νe, we find a branching fraction ratio of BD0→ρ−μ+νμ/BD0→ρ−e+νe=0.90±0.11, which agrees with the theoretical expectation of lepton flavor universality within the uncertainty. Combining the world average of BD+→ρ0μ+νμ and the lifetimes of D0(+), we obtain a partial decay width ratio of ΓD0→ρ−μ+νμ/(2ΓD+→ρ0μ+νμ)=0.71±0.14, which is consistent with the isospin symmetry expectation of unity within 2.1σ. For the reported values of BD0→ρ−μ+νμ/BD0→ρ−e+νe and ΓD0→ρ−μ+νμ/2ΓD+→ρ0μ+νμ, the uncertainty is the quadratic sum of the statistical and systematic uncertainties.Received 3 June 2021Accepted 26 October 2021DOI:https://doi.org/10.1103/PhysRevD.104.L091103Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBranching fractionLeptonic, semileptonic & radiative decaysParticle interactionsQuark mixingPhysical SystemsCharmed mesonsPropertiesFlavor symmetriesForm factorsTechniquesLepton collidersParticles & Fields