$B_c$ 介子的光谱参数
Spectroscopic parameters of $B_c$ meson
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中文总结 AI 辅助
本研究用非相对论夸克模型计算$B_c$介子光谱与衰变性质，预测$B_c^*$质量和$P$波精细结构排序是检验自旋相关动力学的关键。
中文摘要 AI 辅助
我们在非相对论夸克模型框架内研究了 $B_c$ 介子的光谱和衰变性质。我们计算了 $S$、$P$ 和 $D$ 波扇区中径向和轨道激发态的质量谱、带单圈 QCD 修正的赝标量和矢量衰变常数、E1 和 M1 辐射宽度以及径向 Regge 轨迹。基态及其第一径向激发与实验吻合良好。预测的衰变常数与相对论模型估计一致，并给出了轻子衰变 $B_c\ o\ au\ u_\ au$ 的相应预测。E1 跃迁模式主要由径向波函数重叠决定，最低 $D$ 波多重态的主要跃迁表明 $D\ o P\ o S$ 辐射级联是通往未观测到的 $D$ 波态的有前景途径。该模型预测 $P$ 和 $D$ 波多重态中存在倒置的精细结构排序，反映了单胶子交换（OGE）和禁闭对自旋-轨道相互作用的贡献之间的竞争。允许的 M1 宽度因预测的超精细分裂很小而受到强烈抑制，凸显了直接测量 $B_c^*$ 质量的重要性。径向 Regge 轨迹在所有考虑的族中几乎呈线性，斜率随轨道角动量增加而减小。这些结果将 $B_c^*$ 质量和最低 $P$ 波多重态的精细结构排序确定为检验 $B_c$ 系统自旋相关动力学的关键测量。
英文摘要
We study the spectroscopy and decays of the $B_c$ meson in a nonrelativistic quark model in which all observables follow from a single set of wave functions, with spin-dependent effects included directly in the bound-state equation. With parameters calibrated to the measured $B_c(1S)$ and $B_c(2S)$ masses, we predict the $S$-, $P$-, and $D$-wave spectrum up to $n=5$, the pseudoscalar and vector decay constants with one-loop QCD corrections, the E1 and M1 radiative widths, and the radial Regge trajectories of ten spin-parity families. The $1P$ multiplet is predicted at 6692--6746~MeV with the normal fine-structure ordering, compatible with lattice QCD and located in the region of the two structures observed by LHCb in the $B_c^+γ$ spectrum. The $1D$ states lie near 7008~MeV, below the $BD$ threshold, and all four $D$-wave families are provided. The decay constant $f_{B_c}=507.1$~MeV is consistent with recent QCD sum-rule results and corresponds to $\mathcal{B}(B_c\toτν_τ)\approx3\%$. The E1 widths follow the expected angular weights, while their magnitudes are governed mainly by the radial overlap. The $1P\to1S$ (81--112~keV) and $1D\to1P$ (71--93~keV) widths suggest the $1D\to1P\to1S$ cascade as a promising route toward the first $D$-wave $B_c$ state. The Regge trajectories are nearly linear, with slopes decreasing from about 5.8~GeV$^2$ for the $S$-wave to 4.7--4.8~GeV$^2$ for the $D$-wave states. These results may guide forthcoming measurements at the LHC and future $e^+e^-$ facilities.
发表机构
- Ondokuz Mayis University（Ondokuz Mayis 大学）
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