arXiv 2407.100632024-07-14hep-phnucl-th

负宇称单重重子的双π发射衰变

Two-pion emission decays of negative parity singly heavy baryons

Nongnapat Ponkhuha, Ahmad Jafar Arifi, Daris Samart

备注：: 17 pages, 11 figures

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AI总结：

本研究分析负宇称单重重子的双π发射衰变过程，结合级联与直接过程模型及Dalitz图分析，验证$Λ_c(2625)^+$的夸克模归属并预言其他衰变情形，揭示手征伙伴结构的作用。

摘要：

我们研究了单粲重子和单底重子的双π发射衰变，重点关注含$Q=c$（粲）或$b$（底）夸克、$J^P=1/2^-,3/2^-$、属于反对称味三重态$\bar{\boldsymbol{3}}_F$的$Λ_Q^*(1P)$和$Ξ_Q^*(1P)$。我们的分析涵盖两种过程：一是由手征夸克模型推导的、涉及对称味六重态$\boldsymbol{6}_F$中间态（如$J^P=1/2^+,3/2^+$的$Σ_Q(1S)$和$Ξ_Q^\rime(1S)$）的级联过程；二是对与实验数据对比至关重要的直接过程，其耦合常数采用手征伙伴方案估算。我们还在Dalitz图中纳入了母粒子质量的卷积，使与实验数据的对比更符合实际。结合Belle实验组近期对$Λ_c(2625)^+$的测量结果，我们仔细分析了这些负宇称态的Dalitz图。基于$Λ_cπ$不变质量分布的分析结果支持将$Λ_c(2625)^+$归属为夸克模型中$J^P=3/2^-$的$λ$模激发，随后我们给出了包括$Ξ_Q^*$衰变在内的其他情形的预言。$ππ$不变质量分布中观测到的不对称性凸显了直接过程的重要作用，反映了重重子领域的手征伙伴结构。研究表明，除非$S$波共振贡献被抑制，否则直接过程在三体衰变中的作用并不显著。我们建议开展进一步的实验验证以检验我们的预言，并更深入地认识重重子的结构。

英文摘要：

We investigate two-pion emission decays of singly charmed and bottom baryons, focusing on $Λ_Q^*(1P)$ and $Ξ_Q^*(1P)$ with $Q=c$ (charm) or $b$ (bottom) quarks and $J^P=1/2^-,3/2^-$, belonging to antisymmetric flavor triplet $\bar{\boldsymbol{3}}_F$. Our analysis encompasses both sequential processes, involving intermediate states belonging to symmetric flavor sextet $\boldsymbol{6}_F$ such as $Σ_Q(1S)$ and $Ξ_Q^\prime(1S)$ respectively with $J^P=1/2^+,3/2^+$, derived from the chiral quark model, and direct process crucial for comparison with experimental data, whose coupling constants estimated using the chiral-partner scheme. We also incorporate the convolution of the parent particle's mass for the Dalitz plot, enabling a more realistic comparison with experimental data. We scrutinize the Dalitz plots of these negative parity states in light of recent Belle measurements for $Λ_c(2625)^+$. Our findings support the assignment of $Λ_c(2625)^+$ as the $λ$-mode excitation with $J^P=3/2^-$ in the quark model, deduced from the the ${Λ_cπ}$ invariant mass distribution, and we then give predictions for other cases, including the $Ξ_Q^*$ decays. The observed asymmetry in the ${ππ}$ invariant mass distribution underscores the important role of the direct process, reflecting the chiral-partner structure in the heavy baryon sector. It is evident that the presence of the direct process is not significant in the three-body decays unless the $S$-wave resonance contribution is suppressed. We suggest further experimental verification to test our predictions and get more insights into the structure of heavy baryons.

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