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arXiv 2009.06243hep-phnucl-th
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$U_A (1)$反常对单个重子衰变宽度的抑制

Suppression of decay widths in singly heavy baryons induced by the $U_A (1)$ anomaly

Yohei Kawakami, Masayasu Harada, Makoto Oka, Kei Suzuki

摘要:

基于文献[1]提出的双夸克图像,利用有效手征拉格朗日量研究了激发态单重子的强辐射衰变。有效拉格朗日量包含一个$U_A (1)$反常项,这导致了具有自旋宇称$U_A (1)$的奇异和非奇异SHB之间的逆质量序。我们发现,$U_A (1)$异常结合味道对称性破缺的效果修改Goldberger-Treiman关系的基态$Λ_Q (1/2^+)$和它的手性伙伴$Λ_Q (1/2^-)$之间的质量差,和$Λ_Q (1/2^-) Λ_Q (1/2^+) η$耦合,这导致抑制的衰减宽度的$Λ_Q (1/2^-) \to Λ_Q (1/2^+) η$。我们还研究了其他各种衰变,如$Λ_Q (1/2^-) \to Σ_Q (1/2^+, \, 3/2^+) ππ$,$Λ_Q (1/2^-) \to Σ_Q (1/2^+) π$,$Λ_Q (1/2^-) \to Σ_Q (1/2^+, \, 3/2^+) γ$,和$Λ_Q (1/2^-) \to Λ_Q (1/2^+) π^0$广泛的质量范围的$Λ_Q (1/2^-)$。

英文摘要:

We study strong and radiative decays of excited singly heavy baryons (SHBs) using an effective chiral Lagrangian based on the diquark picture proposed in Ref. [1]. The effective Lagrangian contains a $U_A (1)$ anomaly term, which induces an inverse mass ordering between strange and non-strange SHBs with spin-parity $1/2^-$. We find that the effect of the $U_A (1)$ anomaly combined with flavor-symmetry breaking modifies the Goldberger-Treiman relation for the mass difference between the ground state $Λ_Q (1/2^+)$ and its chiral partner $Λ_Q (1/2^-)$, and $Λ_Q (1/2^-) Λ_Q (1/2^+) η$ coupling, which results in suppression of the decay width of $Λ_Q (1/2^-) \to Λ_Q (1/2^+) η$. We also investigate the other various decays such as $Λ_Q (1/2^-) \to Σ_Q (1/2^+, \, 3/2^+) ππ$, $Λ_Q (1/2^-) \to Σ_Q (1/2^+) π$, $Λ_Q (1/2^-) \to Σ_Q (1/2^+, \, 3/2^+) γ$, and $Λ_Q (1/2^-) \to Λ_Q (1/2^+) π^0$ for wide range of mass of $Λ_Q (1/2^-)$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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