Observation of the W -annihilation decay Ds+ →ωπ+ and evidence for Ds+ →ωK+

Abstract

We report the observation of W-annihilation decay D-s(+) -> omega pi(+) and evidence for D-s(+) -> omega K+ in a data sample corresponding to an integrated luminosity of 3.19 fb(-1) collected with the BESIII detector at a center-of-mass energy root s = 4.178 GeV. We obtain the branching fractions B(D-s(+) -> omega pi(+)) = (1.77 +/- 0.32(stat) +/- 0.13(sys)) x 10(-3) with a significance of 6.7 sigma and B(D-s(+) -> omega K+) = (0.87 +/- 0.24(stat) +/- 0.08(sys)) x 10(-3) with a significance of 4.4 sigma. This measurement provides critical information to determine the nonperturbative W-annihilation amplitudes and shows the potential of searching for CP asymmetry in D-s(+) -> omega K+.