A Study of Xi_c(2980)^+ and Xi_c(3077)^+

TL;DR

This paper reports the observation and measurement of two excited Xi_c^+ baryon states decaying into Lambda_c^+K^-pi^+ using data from the BaBar detector, providing new insights into charmed baryon spectroscopy.

Contribution

First measurement of Xi_c(2980)^+ and Xi_c(3077)^+ states' properties, including masses, widths, and decay modes, using BaBar data near the Upsilon(4S) resonance.

Findings

Observed Xi_c(2980)^+ with 7.0 sigma significance, mass difference 680.6 MeV/c^2, width 23.6 MeV.

Observed Xi_c(3077)^+ with 8.6 sigma significance, mass difference 790.0 MeV/c^2, width 6.2 MeV.

Identified decay modes including resonant decays through Sigma_c(2455)^{++}K^- and Sigma_c(2520)^{++}K^-.

Abstract

We present a study of two states decaying to Lambda_c^+K^-pi^+ using the BaBar detector at the SLAC PEP-II asymmetric-energy e^+e^- storage rings. We use an integrated luminosity of 288.5 fb^{-1} collected at the center-of-mass energy sqrt{s} = 10.58 GeV, near the peak of the Upsilon(4S) resonance, plus 27.2 fb^{-1} collected approximately 40 MeV below this energy. We search for the particles Xi_{c}(2980)^+ and Xi_{c}(3077)^+, recently discovered by the Belle Collaboration, in their decays to Lambda_c^+K^-pi^+, where Lambda_c^+rightarrow pK^-pi^+. We find a signal with 7.0 sigma significance for the Xi_c(2980)^+ state with a mass difference with respect to the Lambda_c^+ of (680.6pm1.9pm1.0) MeV/c^2 (first error is statistical and second error is systematic). The measured width for this state is (23.6pm2.8pm1.3) MeV, and the yield is 284pm45pm46 events. We find a signal with 8.6 sigma significance for the Xi_c(3077)^+ state with a mass difference with respect to the Lambda_c^+ of (790.0pm0.7pm0.2) MeV/c^2, a width of (6.2pm1.6pm0.5) MeV, and a yield of 204pm35pm12 events. The Xi_{c}(2980)^+ is found to decay resonantly through the intermediate state Sigma_c(2455)^{++}K^- with 4.9 sigma significance and non-resonantly to Lambda_c^+K^-pi^+ with 4.1 sigma significance. With 5.8 sigma significance, the Xi_c(3077)^+ is found to decay resonantly through Sigma_c(2455)^{++}K^-, and with 4.6 sigma significance, it is found to decay through Sigma_c(2520)^{++}K^-. The significance of the signal for the non-resonant decay Xi_c(3077)^+rightarrow Lambda_c^+K^-pi^+ is 1.4 sigma. These results are preliminary.