In this article, we perform a sensitivity study of an un-binned angular analysis of the $Bto D^*ell u_ell$ decay, including the contributions from the right-handed current. We show that the angular observable can constrain very strongly the right-ha
nded current without the intervention of the yet unsolved $V_{cb}$ puzzle.
We revisit QCD calculations of radiative heavy meson decay form factors by including the subleading power corrections from the twist-two photon distribution amplitude at next-to-leading-order in $alpha_s$ with the method of the light-cone sum rules (
LCSR). The desired hard-collinear factorization formula for the vacuum-to-photon correlation function with the interpolating currents for two heavy mesons is constructed with the operator-product-expansion technique in the presence of evanescent operators. Applying the background field approach, the higher twist corrections from both the two-particle and three-particle photon distribution amplitudes are further computed in the LCSR framework at leading-order in QCD, up to the twist-four accuracy. Combining the leading power point-like photon contribution at tree level and the subleading power resolved photon corrections from the newly derived LCSR, we update theory predictions for the nonperturbative couplings describing the electromagnetic decay processes of the heavy mesons $H^{ast , pm} to H^{pm} , gamma$, $H^{ast , 0} to H^{0} , gamma$, $H_s^{ast , pm} to H_s^{pm} , gamma$ (with $H=D, , B$). Furthermore, we perform an exploratory comparisons of our sum rule computations of the heavy-meson magnetic couplings with the previous determinations based upon different QCD approaches and phenomenological models.
Applying the vacuum-to-$B$-meson correlation functions with an interpolating current for the light vector meson we construct the light-cone sum rules (LCSR) for the effective form factors $xi_{parallel}(n cdot p)$, $xi_{perp}(n cdot p)$, $Xi_{paralle
l}(tau, n cdot p)$ and $Xi_{perp}(tau, n cdot p)$, defined by the corresponding hadronic matrix elements in soft-collinear effective theory (SCET), entering the leading-power factorization formulae for QCD form factors responsible for $B to V ell bar u_{ell}$ and $B to V ell bar ell$ decays at large hadronic recoil at next-to-leading-order in QCD. The light-quark mass effect for the local SCET form factors $xi_{parallel}(n cdot p)$ and $xi_{perp}(n cdot p)$ is also computed from the LCSR method with the $B$-meson light-cone distribution amplitude $phi_B^{+}(omega, mu)$ at ${cal O}(alpha_s)$. Furthermore, the subleading power corrections to $B to V$ form factors from the higher-twist $B$-meson light-cone distribution amplitudes are also computed with the same method at tree level up to the twist-six accuracy. Having at our disposal the LCSR predictions for $B to V$ form factors, we further perform new determinations of the CKM matrix element $|V_{ub}|$ from the semileptonic $B to rho , ell , bar u_{ell}$ and $B to omega , ell , bar u_{ell}$ decays, and predict the normalized differential branching fractions and the $q^2$-binned $K^{ast}$ longitudinal polarization fractions of the exclusive rare $B to K^{ast} , u_{ell} , bar u_{ell}$ decays.
In this paper we investigate the power suppressed contributions from two-particle and three-particle twist-4 light-cone distribution amplitudes (LCDAs) of photon within the framework of light-cone sum rules. Compared with leading twist LCDA result, t
he contribution from three-particle twist-4 LCDAs is not suppressed in the expansion by $1/Q^2$, so that the power corrections considered in this work can give rise to a sizable contribution, especially at low $Q^2$ region. According to our result, the power suppressed contributions should be included in the determination of the Gegenbauer moments of pion LCDAs with the pion transition form factor.
We update QCD calculations of $B to pi, K$ form factors at large hadronic recoil by including the subleading-power corrections from the higher-twist $B$-meson light-cone distribution amplitudes (LCDAs) up to the twist-six accuracy and the strange-qua
rk mass effects at leading-power in $Lambda/m_b$ from the twist-two $B$-meson LCDA $phi_B^{+}(omega, mu)$. The higher-twist corrections from both the two-particle and three-particle $B$-meson LCDAs are computed from the light-cone QCD sum rules (LCSR) at tree level. In particular, we construct the local duality model for the twist-five and -six $B$-meson LCDAs, in agreement with the corresponding asymptotic behaviours at small quark and gluon momenta, employing the QCD sum rules in heavy quark effective theory at leading order in $alpha_s$. The strange quark mass effects in semileptonic $B to K$ form factors yield the leading-power contribution in the heavy quark expansion, consistent with the power-counting analysis in soft-collinear effective theory, and they are also computed from the LCSR approach due to the appearance of the rapidity singularities. We further explore the phenomenological aspects of the semileptonic $B to pi ell u$ decays and the rare exclusive processes $B to K u u$, including the determination of the CKM matrix element $|V_{ub}|$, the normalized differential $q^2$ distributions and precision observables defined by the ratios of branching fractions for the above-mentioned two channels in the same intervals of $q^2$.
Within the framework of $B$-meson light-cone sum rules, we compute the one-loop level QCD corrections to $Bto pi$ transition form factors at small $ q^{2}$ region, in implement of a complete renormalization group equation evolution. To solve the reno
rmalization group equations, we work at the dual space where the anomalous dimensions of the jet function and the light-cone distribution amplitudes are diagonal. With the complete renormalization group equation evolution, the form factors are almost independent of the factorization scale, which is shown numerically. We also extrapolate the results of the form factors to the whole $q^2$ region, and compare their behavior with other studies.
The radiative B-> rho gamma, B-> omega gamma decay modes are caused by the FCNC process, so they give us good insight towards probing the standard model in order to search for new physics. In this paper, we compute the branching ratio, direct CP asym
metry, and isospin breaking effects using the perturbative QCD approach within the standard model.
We study the influence of messenger Yukawa couplings and top, bottom and $tau$ Yukawa couplings on the proton lifetime in SU(5) Supersymmetric GUT with dynamical supersymmetry breaking mechanism due to Dine and Nelson.
