Measurement of the Branching Fraction B(Λ+c→pK−π+)

We present the first model-independent measurement of the absolute branching fraction of the Λ+c→pK-π+ decay using a data sample of 978 fb-1 collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. The number of Λ+c baryons is determined by reconstructing the recoiling D(*)-p¯π+ system in events of the type e+e-→D(*)-p¯π+Λ+c. The branching fraction is measured to be B(Λ+c→pK-π+)=(6.84±0.24+0.21-0.27)%, where the first and second uncertainties are statistical and systematic, respectively.