论文标题
$ b_ {d，s} \toγ\ ell \ bar {\ ell} $用充满活力的光子衰减
$B_{d,s}\toγ\ell\bar{\ell}$ decay with an energetic photon
论文作者
论文摘要
我们计算出$ b_ {d，s} \toγ\ ell \ bar {\ ell} $衰减的差分分支分数，Lepton向前不对称和直接CP不对称。我们采用分解方法，在大能/夸克扩展中引起强力耦合，从而导致严格的临时订单预测，以及估计功率校正和谐振参数的估计以及在小Lepton Invariant Mass $ q^2 $的小型Lepton Invariant Mass $ q^2 $中的子领导功率形式的谐振参数化。 $ b_ {d，s} \toγ\ ell \ bar {\ ell} $衰减分享了带电的电流衰减的特征$ b_u \toγ\ ell \ ell \barν_\ ell $，fcnc衰减$ b \ to k^{（*）} \ ell \ bar \ ell $ bar \ ell $。与前者一样，可以用$ b $ -Meson轻锥分布幅度和短途因素表示领先的衰减率。 However, similar to $B\to K^{(*)}\ell\bar\ell$, four-quark and dipole operators contribute to the $B_{d,s}\toγ\ell\bar{\ell}$ decay in an essential way, limiting the calculation to $q^2\lesssim 6\,$GeV$^2$ below the charmonium resonances in the lepton不变质谱。提出了对主要可观察物和理论不确定性的详细分析。
We calculate the differential branching fraction, lepton forward-backward asymmetry and direct CP asymmetry for $B_{d,s}\toγ\ell\bar{\ell}$ decays with an energetic photon. We employ factorization methods, which result in rigorous next-to-leading order predictions in the strong coupling at leading power in the large-energy/heavy-quark expansion, together with estimates of power corrections and a resonance parameterization of sub-leading power form factors in the region of small lepton invariant mass $q^2$. The $B_{d,s}\toγ\ell\bar{\ell}$ decay shares features of the charged-current decay $B_u \to γ\ell\barν_\ell$, and the FCNC decays $B\to K^{(*)}\ell\bar\ell$. As in the former, the leading-power decay rates can be expressed in terms of the $B$-meson light-cone distribution amplitude and short-distance factors. However, similar to $B\to K^{(*)}\ell\bar\ell$, four-quark and dipole operators contribute to the $B_{d,s}\toγ\ell\bar{\ell}$ decay in an essential way, limiting the calculation to $q^2\lesssim 6\,$GeV$^2$ below the charmonium resonances in the lepton invariant mass spectrum. A detailed analysis of the main observables and theoretical uncertainties is presented.
