Search for heavy Majorana neutrino in lepton number violating decays of D → Kπe ~+ e ~+

摘要

Using a data sample with an integrated luminosity of 2.93 fb~(?1) taken at the center-of-mass energy of 3.773GeV,we search for theMajorana neutrino (νm) in the lepton number violating decays D → Kπe~+e~+. No significant signal isobserved, and theupper limitsonthe branching fractionat the 90%confidence level are set to be B(D~0 → K~?π~?e~+e~+) < 2.8 × 10~(?6), B(D~+ → K_S~0π~?e~+e~+) < 3.3 × 10~(?6) and B(D~+ → K~?π~0e~+e~+) < 8.5 × 10~(?6). The Majorana neutrino is searched for with different mass assumptions ranging from 0.25 to 1.0 GeV/c~2 in the decays D~0 → K~?e~+ν_m; ν_m → π~?e~+ and D~+ → K_S~0e~+ν_m; ν_m → π~?e~+, and the upper limits on the branching fraction at the 90%confidence level are at the level of 10~(?7) ～ 10~(?6), depending on themass of the Majorana neutrino. The constraints on the mixing matrix element |V_(eνm)|~2 are also evaluated.