The spin-parity study of the Lambda_c(2765)+ in Belle

Abstract

The Λ(1405) resonance is difficult to describe in terms of an ordinary three quark state. One promising explanation is that Λ(1405) actually consists of two poles which couple to the K? N and πΣ channel, respectively This overlap might be separated in charm sector so that we can actually find two states, since mass difference between πΣc and DN is larger than in the strange sector. Λc(2593)+ has the same spin-parity as the Λ(1405), and can be considered as the πΣc resonance. A corresponding DN bound state candidate is the Λc(2765)+, whose spin-parity is yet unknown. We use the Belle experiment full data to assign spin and parity of the Λc(2765)+. We report the angular distribution study in Λc(2765)+? > Σc(2455)π channel and Λc(2765)+? > Σc(2520)π channel for spin determination. We also report the study of the branching fraction for Λc(2765)+? > Σc(2455)/Σc(2520)π decay to find the parity with heacy quark symmetry. As a result, the spin of the Λc(2765)+ is determined for 1/2 and parity is detemined for +.