Observation of the Cabibbo-suppressed decay Xi_c+ -> p K- pi+

TL;DR

This paper reports the first observation of a rare charm baryon decay, measuring its branching fractions relative to other decay modes using data from Fermilab's SELEX experiment.

Contribution

It provides the first experimental evidence of the Cabibbo-suppressed decay Xi_c+ -> p K- pi+ and measures its branching ratios relative to other decay channels.

Findings

Observed 150 ± 22 events for the decay.

Measured branching fraction ratios with uncertainties.

First experimental evidence of this decay mode.

Abstract

We report the first observation of the Cabibbo-suppressed charm baryon decay Xi_c+ -> p K- pi+. We observe 150 +- 22 events for the signal. The data were accumulated using the SELEX spectrometer during the 1996-1997 fixed target run at Fermilab, chiefly from a 600 GeV/c Sigma- beam. The branching fractions of the decay relative to the Cabibbo-favored Xi_c+ -> Sigma+ K- pi+ and Xi_c+ -> X- pi+ pi+ are measured to be B(Xi_c+ -> p K- pi+)/B(Xi_c+ -> Sigma+ K- pi+) = 0.22 +- 0.06 +- 0.03 and B(Xi_c+ -> p K- pi+)/B(Xi_c+ -> X- pi+ pi+) = 0.20 +- 0.04 +- 0.02, respectively.