Search for the semileptonic decays Ξc0→Ξ0ℓ+ℓ− at Belle

Abstract

Using the full data sample of 980 fb−1 collected with the Belle detector at the KEKB asymmetric energy electron-positron collider, we report the results of the first search for the rare semileptonic decays Ξc0→Ξ0ℓ+ℓ− (ℓ=e or μ). No significant signals are observed in the Ξ0ℓ+ℓ− invariant-mass distributions. Taking the decay Ξc0→Ξ−π+ as the normalization mode, we report 90% credibility upper limits on the branching fraction ratios B(Ξc0→Ξ0e+e−)/B(Ξc0→Ξ−π+)<6.7×10−3 and B(Ξc0→Ξ0μ+μ−)/B(Ξc0→Ξ−π+)<4.3×10−3 based on the phase-space assumption for signal decays. The 90% credibility upper limits on the absolute branching fractions of B(Ξc0→Ξ0e+e−) and B(Ξc0→Ξ0μ+μ−) are found to be 9.9×10−5 and 6.5×10−5, respectively. Published by the American Physical Society 2024