ترغب بنشر مسار تعليمي؟ اضغط هنا

The $D_s$-meson leading-twist distribution amplitude within the QCD sum rules and its application to the $B_s to D_s$ transition form factor

82   0   0.0 ( 0 )
 نشر من قبل Yi Zhang
 تاريخ النشر 2021
  مجال البحث
والبحث باللغة English




اسأل ChatGPT حول البحث

We make a detailed study on the $D_s$ meson leading-twist LCDA $phi_{2;D_s}$ by using the QCD sum rules within the framework of the background field theory. To improve the precision, its moments $langle xi^nrangle _{2;D_s}$ are calculated up to dimension-six condensates. At the scale $mu = 2{rm GeV}$, we obtain: $langle xi^1rangle _{2;D_s}= -0.261^{+0.020}_{-0.020}$, $langle xi^2rangle _{2;D_s} = 0.184^{+0.012}_{-0.012}$, $langle xi^3rangle _{2;D_s} = -0.111 ^{+0.007}_{-0.012}$ and $langle xi^4rangle _{2;D_s} = 0.075^{+0.005}_{-0.005}$. Using those moments, the $phi_{2;D_s}$ is then constructed by using the light-cone harmonic oscillator model. As an application, we calculate the transition form factor $f^{B_sto D_s}_+(q^2)$ within the light-cone sum rules (LCSR) approach by using a right-handed chiral current, in which the terms involving $phi_{2;D_s}$ dominates the LCSR. It is noted that the extrapolated $f^{B_sto D_s}_+(q^2)$ agrees with the Lattice QCD prediction. After extrapolating the transition form factor to the physically allowable $q^2$-region, we calculate the branching ratio and the CKM matrix element, which give $mathcal{B}(bar B_s^0 to D_s^+ ell u_ell) = (2.03^{+0.35}_{-0.49}) times 10^{-2}$ and $|V_{cb}|=(40.00_{-4.08}^{+4.93})times 10^{-3}$.



قيم البحث

اقرأ أيضاً

In this paper, we make a detailed discussion on the $eta$-meson leading-twist light-cone distribution amplitude (LCDA) $phi_{2;eta}(u,mu)$ by using the QCD sum rules approach under the background field theory. Taking both the non-perturbative condens ates up to dimension-six and the next-to-leading order (NLO) QCD corrections to the perturbative part, its first three moments $langlexi^n_{2;eta}rangle|_{mu_0} $ with $n = (2, 4, 6)$ can be determined, where the initial scale $mu_0$ is set as the usual choice of $1$ GeV. Numerically, we obtain $langlexi_{2;eta}^2rangle|_{mu_0} =0.204_{-0.012}^{+0.008}$, $langlexi_{2;eta}^4 rangle|_{mu_0} =0.092_{ - 0.007}^{ + 0.006}$, and $langlexi_{2;eta}^6 rangle|_{mu_0} =0.054_{-0.005}^{+0.004}$. Next, we calculate the $D_stoeta$ transition form factor (TFF) $f_{+}(q^2)$ within the QCD light-cone sum rules approach up to NLO level. Its value at the large recoil region is $f_{+}(0) = 0.484_{-0.036}^{+0.039}$. After extrapolating the TFF to the allowable physical region, we then obtain the total decay widthes and the branching fractions of the semi-leptonic decay $D_s^+toetaell^+ u_ell$, i.e. $Gamma(D_s^+ toeta e^+ u_e)=(31.197_{-4.323}^{+5.456})times 10^{-15}~{rm GeV}$, ${cal B}(D_s^+ toeta e^+ u_e)=2.389_{-0.331}^{+0.418}$ for $D_s^+ toeta e^+ u_e$ channel, and $Gamma(D_s^+ toetamu^+ u_mu)=(30.849_{-4.273}^{+5.397})times 10^{-15}~{rm GeV}$, ${cal B}(D_s^+ toetamu^+ u_mu)=2.362_{-0.327}^{+0.413}$ for $D_s^+ toetamu^+ u_mu$ channel respectively. Those values show good agreement with the recent BES-III measurements.
The form factors and coupling constants of the meson vertices J/psi D_s D_s and phi D_s D_s were calculated using three point correlation functions within the QCD Sum Rules formalism. We have considered the cases where phi, D_s and J/psi mesons are o ff-shell obtaining, for each vertex, two different form factors and its corresponding coupling constants, namely g_{J/psi D_s D_s} = 6.20^{+0.97}_{-1.15} and g_{phi D_s D_s} = 1.85^{+0.22}_{-0.23}.
In this work, we calculate the form factors and the coupling constant of the strange-charmed vertex $J/psi D_s^* D_s$ in the framework of the QCD sum rules by studying their three-point correlation functions. All the possible off-shell cases are cons idered, $D_s$, $D_s^*$ and $J/psi$, resulting in three different form factors. These form factors are extrapolated to the pole of their respective off-shell mesons, giving the same coupling constant for the process. Our final result for the $J/psi D_s^* D_s$ coupling constant is $g_{J/psi D^*_s D_s} = 4.30^{+0.42}_{-0.37}text{GeV}^{-1}$.
We present an improved calculation on the pionic twist-3 distribution amplitudes $phi^{pi}_{p}$ and $phi^{pi}_{sigma}$, which are studied within the QCD sum rules. By adding all the uncertainties in quadrature, it is found that $<xi^2_p>=0.248^{+0.07 6}_{-0.052}$, $<xi^4_p>=0.262^{+0.080}_{-0.055}$, $<xi^2_sigma>=0.102^{+0.035}_{-0.025}$ and $<xi^4_sigma>=0.094^{+0.028}_{-0.020}$. Furthermore, with the help of these moments, we construct a model for the twist-3 wave functions $psi^{pi}_{p,sigma}(x,mathbf{k}_bot)$, which have better end-point behavior and are helpful for perturbative QCD approach. The obtained twist-3 distribution amplitudes are adopted to calculate the $Btopi$ transition form factor $f^+_{Bpi}$ within the QCD light-cone sum rules up to next-to-leading order. By suitable choice of the parameters, we obtain a consistent $f^+_{Bpi}$ with those obtained in the literature.
We study the $B to rho$ helicity form factors (HFFs) by applying the light-cone sum rules up to twist-4 accuracy. The HFF has some advantages in comparison to the conventionally calculated transition form factors, such as the HFF parameterization can be achieved via diagonalizable unitarity relations and etc. At the large recoil point, only the $rho$-meson longitudinal component contributes to the HFFs, and we have $mathcal{H}_{rho,0}(0)=0.435^{+0.055}_{-0.045}$ and $mathcal{H}_{rho,{1,2}}(0)equiv 0$. We extrapolate the HFFs to physically allowable $q^2$-region and apply them to the $B to rho$ semileptonic decay. We observe that the $rho$-meson longitudinal component dominates its differential decay width in low $q^2$-region, and its transverse component dominates the high $q^2$-region. Two ratios $R_{rm low}$ and $R_{rm high}$ are used to characterize those properties, and our LCSR calculation gives, $R_{rm low}=0.967^{+0.305}_{-0.284}$ and $R_{rm high}=0.219^{+0.058}_{-0.070}$, which agree with the BaBar measurements within errors.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا