手征幺正方法讨论a_(1)(1260)性质

Investigate the nature of a_(1)(1260)with the chiral unitary approach

在手征幺正方法下,研究了强子共振态的三角奇异性.主要讨论了由a_(1)(1260)到π^(+)f_(0)(980)和π^(+)ρ^(0)的三角奇异衰变机制、参数变化对衰变不变质量分布、衰变宽度和微分散射截面的影响.通过对研究结果的分析,成功解释了1420 MeV峰的来源,及COMPASS实验a_(1)^(+)(1260)→π^(+)f_(0)(980)和a_(1)^(+)(1260)→π^(+)ρ^(0)的衰变分支比.因此,COMPASS实验中1420 MeV峰并非一个新共振态,而是a_(1)(1260)三角奇异衰变机制的产物,并且在衰变过程中,看到了一个高于其名义质量200 MeV的峰值.该文讨论的三角奇异衰变机制有助于以全新视角重新审视粒子数据表的共振态实验数据.

In this paper,the nature of hadron resonance state is investigated by studying the triangle singularity mechanism with the chiral unitary approach.The decay modes of a_(1)(1260)intoπ^(+)f_(0)(980)andπ^(+)ρ^(0)of the triangle singularity mechanism are studied,and the the effects of parameters on the invariant mass distribution,decay width and differential cross section is discussed.The results showed that the peak of 1420 MeV and decay ratio of COMPASS experiments for a_(1)^(+)(1260)→π^(+)f_(0)(980)and a_(1)^(+)(1260)→π^(+)ρ^(0)processes.Hence,the peak is not a new resonance,but a result of the triangle singularity mechanism.Another interesting thing is that we see how a decay mode of one reasonace can peak at 200 MeV higher energy than the nominal resonance mass.The present work will be helpful in investigating many other interesting resonance states in PDG from the view of triangle singularity mechanism.