论文标题
$λ_b\ to p $过渡形式扰动QCD
$Λ_b\to p$ transition form factors in perturbative QCD
论文作者
论文摘要
我们将$λ_b\ \ to $λ_b\ \ p $ the Tormition形式在扰动QCD（PQCD）方法中通过包括$λ_b$ baryon和proton的较高扭转轻锥分布幅度（LCDA），将其重新分析。几十年前进行的先前的PQCD评估仅使用领先的$λ_b$ baryon和Proton LCDA提供了形式因素，这比实验数据指示的小两个数量级。我们发现Twist-4 $λ_b$ baryon lcdas和twist-4和-5质子LCDA会产生巨大贡献，并且增强的外形因素与lattice QCD和其他非视扰方法的构造因素变得一致。半衰减衰减的估计分支比$λ_b\ \ ell \ ell \barν_\ ell $和HADRONIC DECAY $λ_B\ topπ$也接近数据。这意味着$ b $ Quark质量的重量不够重，并且更高的贡献起着至关重要的作用，类似于分析$ B $ Meson过渡形式的分析。在这项工作中建立的形式主义之后，我们准备在PQCD方法中系统地研究各种重型重鸡。
We reanalyze the $Λ_b\to p$ transition form factors in the perturbative QCD (PQCD) approach by including higher-twist light-cone distribution amplitudes (LCDAs) of a $Λ_b$ baryon and a proton. The previous PQCD evaluation performed decades ago with only the leading-twist $Λ_b$ baryon and proton LCDAs gave the form factors, which are two orders of magnitude smaller than indicated by experimental data. We find that the twist-4 $Λ_b$ baryon LCDAs and the twist-4 and -5 proton LCDAs contribute dominantly, and the enhanced form factors become consistent with those from lattice QCD and other nonperturbative methods. The estimated branching ratios of the semileptonic decays $Λ_b\to p\ell\barν_\ell$ and the hadronic decay $Λ_b\to pπ$ are also close to the data. It implies that the $b$ quark mass is not really heavy enough, and higher-power contributions play a crucial role, similar to the observation made in analyses of $B$ meson transition form factors. With the formalism established in this work, we are ready to study various exclusive heavy baryon decays systematically in the PQCD approach.
