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arXiv 1012.5098hep-ph
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重强子半轻子衰变率比

Ratios of heavy hadron semileptonic decay rates

Michael Gronau, Jonathan L. Rosner

摘要:

粲介子和重子半轻子衰变率的比率似乎是令人满意的描述,只考虑最低躺(S波)强子的最终状态,并假设描述相空间抑制的运动学因子是相同的自由夸克。例如,已知$D_s$半轻子衰变的速率为$(17.0 \pm 5.3)%$,低于$D^0$或$D^+$的速率,模型解释了这种差异。当应用于含$b$夸克的强子时,这种方法意味着$B_s$的半轻子衰变率比非奇异$B$介子的半轻子衰变率高约1%.因此,这个小的差异表明$B$半轻子衰变具有令人惊讶的良好的局域夸克-强子对偶性,补充了基于包容夸克-强子对偶性的期望,即这些速率的差异不应超过百分之零点几。然而,对于$Λ_b$半轻子衰变,包含率比非奇异$B$介子的包含率大13%。这个值,代表了一个相当大的偏离使用重夸克膨胀的计算,是接近相应的实验比率$Γ(Λ_b)/ \bar Γ(B) = 1.13 \pm 0.03$的总衰变率。

英文摘要:

Ratios of charmed meson and baryon semileptonic decay rates appear to be satisfactorily described by considering only the lowest-lying (S-wave) hadronic final states and assuming the kinematic factor describing phase space suppression is the same as that for free quarks. For example, the rate for $D_s$ semileptonic decay is known to be $(17.0 \pm 5.3)%$ lower than those for $D^0$ or $D^+$, and the model accounts for this difference. When applied to hadrons containing $b$ quarks, this method implies that the $B_s$ semileptonic decay rate is about 1% higher than that of the nonstrange $B$ mesons. This small difference thus suggests surprisingly good local quark-hadron duality for $B$ semileptonic decays, complementing the expectation based on inclusive quark-hadron duality that these differences in rates should not exceed a few tenths of a percent. For $Λ_b$ semileptonic decay, however, the inclusive rate is predicted to be about 13% greater than that of the nonstrange $B$ mesons. This value, representing a considerable departure from a calculation using a heavy quark expansion, is close to the corresponding experimental ratio $Γ(Λ_b)/ \bar Γ(B) = 1.13 \pm 0.03$ of total decay rates.

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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