标题： 从Lambda_c的弱衰变确定pi Sigma散射长度 显示英文标题

标题： Determination of the pi Sigma scattering lengths from the weak decays of Lambda_c

摘要： πΣ系统的散射长度是理解Λ(1405)共振结构和反K N相互作用的次阈值外推的关键量。 我们证明，可以通过弱Λ_c → ππΣ衰变中的阈值尖峰现象提取πΣ散射长度，这类似于Cabibbo用于确定ππ散射长度的方法。 我们表明，当I=0的πΣ相互作用强烈吸引以产生接近阈值的奇点时，例如束缚态或虚态，在谱中应该观察到显著的尖峰效应。 显示英文摘要

摘要： The scattering lengths of the pi Sigma systems are key quantities in understanding the structure of the Lambda(1405) resonance and the subthreshold extrapolation of the barK N interaction. We demonstrate that the pi Sigma scattering lengths can be extracted from the threshold cusp phenomena in the weak Lambda_c -> pi pi Sigma decays, analogously with Cabibbo's method for determination of the pi pi scattering length. We show that the substantial cusp effect should be observed in the spectrum, when the pi Sigma interaction in I=0 is strongly attractive to generate a near-threshold singularity, such as a bound state or a virtual state.