AbstractWe report the first measurement of the absolute branching fraction of the inclusive decay $$\Lambda _c^+ \rightarrow K_S^0X$$
Λ
c
+
→
K
S
0
X
. The analysis is performed using an $$e^+e^-$$
e
+
e
-
collision data sample corresponding to an integrated luminosity of 567 $$\hbox {pb}^{-1}$$
pb
-
1
taken 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
(
Λ
c
+
→
K
S
0
X
)
=
(
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.
Measurement of the Absolute Branching Fraction of the Inclusive Decay
Λc+→Λ+X
