Confirmation of the Double Charm Baryon Xi_cc+ via its Decay to p D+ K-

TL;DR

This paper reports the confirmation of the double charm baryon Xi_cc+ through its decay to p D+ K-, providing new evidence that supports its identification as a double charm baryon with a measured mass around 3518 MeV/c^2.

Contribution

The study confirms the Xi_cc+ baryon in a new decay mode, strengthening evidence for its existence and properties, and provides a precise mass measurement consistent with previous results.

Findings

Observation of a 5.62 event excess over background

Measured mass of the Xi_cc+ baryon at 3518 MeV/c^2

Branching ratio of decay modes is approximately 0.36

Abstract

We observes a signal for the double charm baryon Xi_cc+ in the charged decay mode Xi_cc+ -> p D+ K- to complement the previously reported decay Xi_cc+ -> Lambda_c K- pi+ in data from SELEX, the charm hadro-production experiment (E781) at Fermilab. In this new decay mode we observe an excess of 5.62 events over an expected background estimated by event mixing to be 1.38+/-0.13 events. The Poisson probability that a background fluctuation can produce the apparent signal is less than 6.4E-4. The observed mass of this state is (3518+/-3)MeV/c^2, consistent with the published result. Averaging the two results gives a mass of (3518.7+/-1.7)MeV/c^2. The observation of this new weak decay mode confirms the previous SELEX suggestion that this state is a double charm baryon. The relative branching ratio Gamma(Xi_cc+ -> pD+K-)/Gamma(Xi_cc+ -> Lambda_c K- pi+) = 0.36+/-0.21.