用光锥求和规则方法研究了$B_{(s)} \to S$的跃迁形状因子，其中$S$表示标量介子。计算结果比用光阵面夸克模型和QCD求和规则方法估计的结果大一倍左右。使用这些形状因子，我们提出了$B \to a_0(1450) l \barν_l $，$B \to K^{\ast}_0(1430) l \bar{l}$，$B_s \to K^{\ast}_0(1430) l \barν_l$和$B_s \to f_0(1500) l \bar{l}$与$l=e, μ, τ$的衰变率的分析。结果表明，$BR(\bar{B}_0 \to a_0(1450) l \barν_l)$和$BR(B_s \to K^{\ast}_0(1430) l \barν_l)$的量级可以达到$10^{-4}$量级，可以在未来的实验中测量到，以阐明标量介子的内部结构。还观察到，$BR(B \to K^{\ast}_0(1430) τ^+ τ^-)$和$BR(B_s \to f_0(1500) τ^+ τ^-)$是一个数量级小于相应的通道的$e^+ e^-$和$μ^+ μ^-$最终状态由于严重抑制相空间。此外，还研究了$B \to K^{\ast}_0(1430) l \bar{l}$和$B_s \to f_0(1500) l \bar{l}$的轻子纵向极化不对称性，除了靠近端点的区域外，$e^+ e^-$和$μ^+ μ^-$对的轻子纵向极化不对称性接近于-1。
英文摘要：
The transition form factors of $B_{(s)} \to S$, with $S$ denoting a scalar meson, are investigated in the light-cone sum rules approach. The numerical values are approximately twice as large as that estimated in the light-front quark model and QCD sum rules approach. Using these form factors, we present the analysis of the decay rates for $B \to a_0(1450) l \barν_l $, $B \to K^{\ast}_0(1430) l \bar{l}$, $B_s \to K^{\ast}_0(1430) l \barν_l$ and $B_s \to f_0(1500) l \bar{l}$ with $l=e, μ, τ$. The results indicate that magnitudes of $BR(\bar{B}_0 \to a_0(1450) l \barν_l)$ and $BR(B_s \to K^{\ast}_0(1430) l \barν_l)$ can arrive at the order of $10^{-4}$, which can be measured in the future experiments to clarify the inner structure of scalar mesons. It is also observed that $BR(B \to K^{\ast}_0(1430) τ^+ τ^-)$ and $BR(B_s \to f_0(1500) τ^+ τ^-)$ are an order of magnitude smaller than the corresponding channels of $e^+ e^-$ and $μ^+ μ^-$ final states due to the heavily suppressed phase space . Moreover, the longitudinal lepton polarization asymmetry for $B \to K^{\ast}_0(1430) l \bar{l}$ and $B_s \to f_0(1500) l \bar{l}$ are also investigated, whose values are close to -1 for the $e^+ e^-$ and $μ^+ μ^-$ pair except the region close to the end points.
In this work, using the covariant light front approach with conventional vertex functions, we estimate the production rates of $D$-wave charmed/charmed-strange mesons via $B_{(s)}$ semileptonic decays. Due to these calculated considerable production rates, it is possible to experimentally search for $D$-wave charmed/charmed-strange mesons via the semileptonic decays, which may provide extra approach to explore $D$-wave charmed/charmed-strange mesons.
We obtain the wave function of mesonic systems interacting via a Cornell potential by applying improved variational approach. We study Isgur-Wise function and its parameters. Then we report our calculations on the parameters of semileptonic decay of B and Bs mesons. B-->D*l$nu$ process is also investigated in this work.
Within the framework of covariant confined quark model, we compute the transition form factors of $D$ and $D_s$ mesons decaying to light scalar mesons $f_0(980)$ and $a_0(980)$. The transition form factors are then utilized to compute the semileptonic branching fractions. We study the channels namely, $D_{(s)}^+ \to f_0(980) \ell^+ ν_\ell$ and $D \to a_0(980) \ell^+ ν_\ell$ for $\ell = e$ and $μ$. For computation of semileptonic branching fractions, we consider the $a_0(980)$ meson to be the conventional quark-antiquark structure and the $f_0(980)$ meson as the admixture of $s\bar{s}$ and ligh…
Exclusive Semileptonic Decays of B Mesons to Orbitally and Radial Excited D
本文在相对论夸克模型下计算了半轻子$\bar B \to X_c$衰变的Isgur-Wise函数，其中$X_c$是具有全自旋$J=0,1,2$或它们的第一激发态的粲介子.相关的矩阵元素计算的直接数值积分，在坐标空间中，的卷积的波函数的$B$介子在休息和$X_c$介子的波函数，根据其反冲因子提升。我们的研究结果与现有文献中发现的其他预测进行了比较。
In the extended $U(3)\times U(3)$ NJL model, semileptonic decays of $ρ$, $ω$, $ϕ$, $η$ and $η'$ mesons in both the ground and first radially excited states are described. Quark loops of the anomalous type are considered, which are based on the vertex $η\to VV$. The obtained results are in satisfactory agreement with the existing experimental data. In addition, a number of predictions for experimentally unmeasured decays of radially excited mesons are presented.
The semileptonic $B_s (B) \to K_2^*(a_2, f_2) \ellν$, $\ell=τ, μ$ transitions are investigated in the frame work of the three-point QCD sum rules. Considering the quark condensate contributions, the relevant form factors of these transitions are estimated. The branching ratios of these channel modes are also calculated and compared with the obtained data for other approaches.
The branching ratios of the semileptonic decay widths of the charm mesons are analyzed, using three different models for the Isgur-Wise functions, such as ${D^0} \to {K^ - }{l^ + }\upsilon $, ${D^0} \to {π^ - }{l^ + }ν$, ${D_s} \to {K^0}{l^ + }ν$ and ${D_s} \to η{l^ + }ν$, where the form factors of these decays are discussed. The mass spectra of the charm mesons are obtained. We use a potential quark model and consider the non-relativistic Hamiltonian of the charm meson as a bound state of the quark-antiquark system. We take into account the harmonic-type confinement and also Hellmann potentia…
Semileptonic $B$ meson decays into the four lightest excited charmed meson states ($D_0^*$, $D_1^*$, $D_1$, and $D_2^*$) and their counterparts with $s$ quarks are investigated, including the full lepton mass dependence. We derive the standard model predictions for the differential branching fractions, as well as predictions for the ratios of the semi-tauonic and light lepton semileptonic branching fractions. These can be systematically improved using future measurements of the total or differential semileptonic rates to $e$ and $μ$, as well as the two-body hadronic branching fractions with a …
Recently, the BESIII collaboration has reported numerous measurements of various $D_{(s)}$ meson semileptonic decays with significantly improved precision. Together with similar studies carried out at BABAR, Belle, and CLEO, new windows to a better understanding of weak and strong interactions in the charm sector have been opened. In light of new experimental data, we review the theoretical description and predictions for the semileptonic decays of $D_{(s)}$ to a pseudoscalar or a vector meson. This review is essentially an extended discussion of our recently published results obtained in the …
Non-factorization effects in heavy mesons and determination of |V_{ub}| from inclusive semileptonic B decays
考虑了重介子衰变中的旁观者轻夸克效应，这种效应在介子上四夸克算符矩阵元因式分解的极限下消失。这些效应包括D^0和D_s介子的总宽度和半轻子衰变率的差异，以及对B^0和B^ \pm进入与弱混合参数V_{ub}的确定有关的通道X_u l nu的包含半轻子衰变率的贡献。如果把所观察到的D_s和D^0介子寿命的差异归因于不可因式分解项，则这些项自然会引起这两种介子的包含半轻子衰变率的显著差异，并导致对衰变B -> X_u l nu的光味依赖贡献。后一种贡献主要影响轻子对不变质量包含谱的上部，并且可能显着超过文献中先前声称的确定的理论不确定度|V_{ub}| ^2从光谱的这一部分。
The form factors of semileptonic $B_{(s)}\to a_{1}(K_1)\, \ell^{+}\ell^{-}$, $ \ell=τ,μ,e$ transitions are investigated in the framework of the light-cone sum rules with $B$-meson distribution amplitudes, which play an important role in exclusive $B$ decays. The $B$-meson distribution amplitudes, $φ_{\pm}(ω)$ are a model-dependent form, so we consider four different parameterizations which can provide a reasonable description of $φ_{\pm}(ω)$ from QCD corrections. The branching fractions of these transitions are calculated. For a better analysis, a comparison of our results with the prediction …
