稀有衰变过程B_u^+→π^+l^+l^-,ρ^+l^+l^-与top夸克双Higgs模型下新物理效应

The New Physics Effects on Rare Decays B_u^+→π^+l^+l^-,ρ^+l^+l^-in a Top Quark Two-Higgs-Doublet Model

利用光锥求和规则得到的形状因子,在标准模型和top夸克双Higgs模型（T2HDM）下计算新物理对衰变过程Bu＋→π＋l＋l-和Bu＋ρ＋l＋l-（l=e,μ）的分支比和前后不对称的贡献.从数值计算结果发现,新物理对这些衰变过程的分支比的贡献不是很大,理论预言与标准模型下的结果符合得很好.top夸克双Higgs模型下新物理对前后不对称的影响很小.对Bu＋π＋（ρ＋）l＋l-衰变过程的较低双轻质量区域内双轻不变质量分布和前后不对称的精确测量,将有助于区分标准模型和新物理模型.

The authors investigated the branching ratios and forward-backward asymmetries（FBAs）of the exclusive decays Bu＋→π＋l＋l-and Bu＋ →ρ＋l＋l-（l=e,μ）in the standard model（SM）and the top quark two-Higgs-doublet model（T2HDM）by employing the form factors from light-cone sum rules.From the numerical results,The authors found that the new physics contributions to the branching ratios are not very large and the theoretical predictions are consistent with the SM ones.The T2HDM effects on FBAs of these decays are small.Precision measurements of the dilepton invariant mass distributions,especially in the lower dilepton mass region,and the FBAs in the decays Bu＋ →π＋（ρ＋）l＋l-will greatly help in discriminating among the SM and the new physics models.