Observation of D+ →ηηπ+ and improved measurement of D0 (+) →ηπ+π-(0)

Abstract

Using an e+e- A nnihilation data sample corresponding to an integrated luminosity of 2.93 fb-1 collected at the center-of-mass energy of 3.773 GeV with the BESIII detector, we measure the absolute branching fractions of D+→ηηπ+, D+→ηπ+π0, and D0→ηπ+π-to be (2.96±0.24±0.10)×10-3, (2.23±0.15±0.10)×10-3, and (1.20±0.07±0.04)×10-3, respectively, where the first uncertainties are statistical and the second ones are systematic. The D+→ηηπ+ decay is observed for the first time, and the branching fractions of D+(0)→ηπ+π0(-) are measured with much improved precision. In addition we test for CP asymmetries in the separated charge-conjugate branching fractions; no evidence of CP violation is found.