Measurement of the absolute branching fraction of the inclusive decay Lambda c+-> KS0X : (BESIII Collaboration)

We report the first measurement of the absolute branching fraction of the inclusive decay$$\Lambda _c^+ \rightarrow K_S^0X$$Λc+→KS0X. The analysis is performed using an$$e^+e^-$$e+e-collision data sample corresponding to an integrated luminosity of 567 $$\hbox {pb}^{-1}$$pb-1taken at$$\sqrt{s}$$s= 4.6 GeV with the BESIII detector. Using eleven Cabibbo-favored$${\bar{\Lambda }}_c^-$$Λ¯c-decay modes and the double-tag technique, this absolute branching fraction is measured to be$${\mathcal {B}}(\Lambda _c^+ \rightarrow K_S^0X)=(9.9\pm 0.6\pm 0.4)\%$$B(Λc+→KS0X)=(9.9±0.6±0.4)%, where the first uncertainty is statistical and the second systematic. The relative deviation between the branching fractions for the inclusive decay and the observed exclusive decays is$$(18.7\pm 8.3)\%$$(18.7±8.3)%, which indicates that there may be some unobserved decay modes with a neutron or excited baryons in the final state.