Measurement of branching fractions of Δ<sub>c</sub><SUP>+</SUP> → ηΛπ<SUP>+</SUP>, ηΣ<SUP>0</SUP>π<SUP>+</SUP>, Λ(1670)π<SUP>+</SUP>, and ηΣ(1385)<SUP>+</SUP>

Abstract

We report branching fraction measurements of four decay modes of the Lambda(+)(c) baryon, each of which includes an eta meson and a Lambda baryon in the final state, and all of which are measured relative to the Lambda(+)(c) -> pK(-) eta(+) decay mode. The results are based on a 980 fb(-1) data sample collected by the Belle detector at the KEKB asymmetric-energy e(+) e(-) collider. Two decays, Lambda(+)(c) -> eta Sigma(0)pi(+) and Lambda(1670)pi(+), are observed for the first time, while the measurements of the other decay modes, Lambda(+)(c) -> eta Lambda pi(+) and eta Sigma(1385)(+), are more precise than those made previously. We obtain relative branching fractions of B(Lambda(+)(c) -> eta Lambda pi(+)) / B(Lambda(+)(c) -> pK(-) pi(+)) = 0.293 +/- 0.003 +/- 0.014, B(Lambda(+)(c) -> eta Sigma(0)pi(+))/B(Lambda(+)(c) -> pK(-) pi(+)) = 0.120 +/- 0.006 +/- 0.010, B(Lambda(+)(c) -> Lambda(1670)pi(+)) x B(Lambda(1670) -> eta Lambda)/B(Lambda(+)(c) -> pK(-) pi(+)) = (5.54 +/- 0.29 +/- 0.73) x 10(-2), and B(Lambda(+)(c) -> eta Sigma(1385)(+))/B(Lambda(+)(c) -> pK(-) pi(+)) = 0.192 +/- 0.006 +/- 0.016. The mass and width of the Lambda(1670) are also precisely determined to be 1674.3 +/- 0.8 +/- 4.9 MeV/c(2) and 36.1 +/- 2.4 +/- 4.8 MeV, respectively, where the uncertainties are statistical and systematic, respectively.