相关论文: QCD corrections to direct B -> J/Psi decays

The decay constants of the pseudoscalar mesons B and B_s are evaluated from QCD sum rules for the pseudoscalar two-point function. Recently calculated perturbative three-loop QCD corrections are incorporated into the sum rule. An analysis…

We present a calculation of the QCD correction factors $\eta_{2B}$ and $\eta_{2K}$ up to Next-to-Leading Order within the MSSM. We took into account the region of low $\tan\beta$ for the Higgs- and chargino sector while neglecting the…

A key issue in making precise predictions in QCD is the uncertainty in setting the renormalization scale $\mu_R$ and thus determining the correct values of the QCD running coupling $\alpha_s(\mu_R^2)$ at each order in the perturbative…

In supersymmetric theories, the main decay modes of scalar quarks are decays into quarks plus charginos or neutralinos, if the gluinos are heavy enough. We calculate the O($\alpha_s$) QCD corrections to these decay modes in the minimal…

In this work we compute the leading logarithmic corrections to the b -> s gamma decay in a dimensional scheme which does not require any definition of the gamma5 matrix. The scheme does not exhibit unconsistencies and it is therefore a…

We propose a QCD-based model for calculation of the non-perturbative corrections to the factorization approximation in the decays of heavy mesons. In the framework of the model, factorization in pseudoscalar transitions holds exactly at the…

QCD running coupling constant $\alpha_s(m_c)$ and $\alpha_s(m_b)$ are determined from heavy quarkonia $c\overline{c}$ and $b\overline{b}$ decays. The decay rates of $V\rightarrow 3g$ and $V\rightarrow e^+ e^-$ for $V=J/\psi$ and $\Upsilon$…

We present in detail a new systematic method which can be used to automatically eliminate the renormalization scheme and scale ambiguities in perturbative QCD predictions at all orders. We show that all of the nonconformal \beta-dependent…

Recently it has been shown that in the large-recoil limit new symmetries emerge which impose various relations on form factors that parametrise the decay of heavy B mesons into light mesons. These symmetry relations are broken by radiative…

The two--loop ${\cal O}(\alpha_s G_F m_t^2)$ corrections to the $b\bar b$ decay rate of the Standard Model Higgs boson as well as its production via $e^+e^- \to ZH$ will be presented. These QCD corrections are obtained by using a low-energy…

The leptonic radiative decay $B \to \gamma l\nu$ is of great importance in the determination of $B$ meson wave functions, and evaluating the form factors $ F_{V,A}$ are the essential problem on the study of this channel. We computed…

We directly fit the QCD dimensional transmutation parameter, Lambda MS-bar, to experimental data on e+e- jet observables, making use of next-to-leading order (NLO) perturbative calculations. In this procedure there is no need to mention,…

Linear and non-linear QCD evolutions at high energy suffer from severe issues related to convergence, due to higher order corrections enhanced by large double and single transverse logarithms. We resum double logarithms to all orders by…

Within the nonrelativistic QCD (NRQCD) factorization framework, we calculate the exclusive decay process \eta_b \to J/\psi J/\psi to next-to-leading order in the strong coupling constant, while at leading order in charm quark relative…

We calculate the alpha_s virtual corrections to the decay width for b --> s gluon in the standard model. Also the corresponding order alpha_s bremsstrahlung corrections are systematically calculated in this paper. The combined result is…

Next-to-Leading-Order(NLO) QCD corrections to double J/psi production in e^+e^- annihilation at sqrt{s}=10.6 GeV are calculated. We find that they greatly decrease the cross section, with a K factor (NLO/LO) ranging from -0.31 to 0.25…

Using the newly available $\alpha_s^6$-order QCD correction to the Higgs decay channel $H\to gg$, we make a detailed discussion on the perturbative properties of the decay width $\Gamma(H\to gg)$ by using the principle of maximum…

Motivated by the deviations observed between the data and the SM predictions of $\mathcal{B}(\bar{B}_s^0\to D_s^+ \pi^-)$ and $\mathcal{B}(\bar{B}_d^0\to D^+ K^-)$, we revisit the $B_{c}^{-}\to J/\psi(\eta_{c}) L^{-}$ decays, with $L=\pi,…

We analyse the top-quark decay at the next-to-next-to-leading order (NNLO) in QCD by using the Principle of Maximum Conformality (PMC) which provides a systematic way to eliminate renormalization scheme and scale ambiguities in perturbative…

We derive the $k_T$ resummation for a transverse-momentum-dependent charmonium wave function, which involves the bottom quark mass $m_b$, the charm quark mass $m_c$, and the charm quark transverse momentum $k_T$, up to the…