Search for the Σ ⁎ state in Λc+→π+π0π−Σ+ decay by triangle singularity

Xie, Ju-Jun  (Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000, China) ; Oset, Eulogio (Departamento de Física Teórica, IFIC, Centro Mixto Universidad de Valencia-CSIC, Institutos de Investigacíon de Paterna, Aptdo. 22085, Valencia, 46071, Spain)

09 April 2019

Abstract: A Σ⁎ resonance with spin-parity JP=1/2− and mass in the vicinity of the K¯N threshold has been predicted in the unitary chiral approach and inferred from the analysis of CLAS data on the γp→K+π0Σ0 reaction. In this work, based on the dominant Cabibbo favored weak decay mechanism, we perform a study of Λc+→π+π0Σ⁎ with the possible Σ⁎ state decaying into π−Σ+ through a triangle diagram. This process is initiated by Λc+→π+K¯⁎N , then the K¯⁎ decays into K¯π and K¯N produce the Σ⁎ through a triangle loop containing K¯⁎NK¯ which develops a triangle singularity. We show that the π−Σ+ state is generated from final state interaction of K¯N in S -wave and isospin I=1 , and the Λc+→π+π0π−Σ+ decay can be used to study the possible Σ⁎ state around the K¯N threshold. The proposed decay mechanism can provide valuable information on the nature of the Σ⁎ resonance and can in principle be tested by facilities such as LHCb, BelleII and BESIII.

Published in: Physics letters B 792 (2019) 450-453
Published by: Elsevier
DOI: 10.1016/j.physletb.2019.04.011
License: CC-BY-3.0

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