Related papers: Three-loop QCD corrections and b-quark decays
Potential-NRQCD offers an effective-theory based approach to heavy-quark physics. While meson Q-anti_Q computations are tractable in pure alpha_s-perturbation theory, more complex many-body quark systems transcend it. A possibility…
In this paper the three-loop polarization functions \Pi(q^2) are calculated for the cases of an external vector, axial-vector, scalar or pseudo-scalar current. Results are presented for the imaginary part which directly leads to the cross…
QCD/HQET matching for the heavy-quark field and heavy-light quark currents with three-loop accuracy is discussed.
We compute the NNLO QCD corrections for the hadroproduction of a pair of off-shell photons in the limit of a large number of quark flavors. We perform a reduction of the two-loop amplitude to master integrals and calculate the latter…
We consider the $\Lambda N\to NN$ weak transition, responsible for a large fraction of the non-mesonic weak decay of hypernuclei. We follow on the previously derived effective field theory and compute the next-to-leading one-loop…
Three-loop corrections to the scalar and pseudo-scalar current correlator are calculated. By applying the large momentum expansion mass terms up to order (m^2/q^2)^4 are evaluated analytically. As an application O(\alpha_s^2) corrections to…
We calculated the complete next-to-leading order(NLO) QCD corrections to the $t\bar t b \bar b$ production process at a $\gamma \gamma$ collider in the standard model(SM). The calculation of the one-loop QCD correction includes the…
We compute the three-loop corrections to the helicity amplitudes for $q\bar{q}\to Q\bar{Q}$ scattering in massless QCD. In the Lorentz decomposition of the scattering amplitude we avoid evanescent Lorentz structures and map the…
It is shown that up to an over all scale the lowest-order QCD corrections to $t\to H^+b$ and to $t\to W^+b$ are the same in the heavy top limit. Asymptotically, they are given by $-{4\alpha_s\over 3\pi}[{\pi^2\over 3}-{5\over 4}]$,…
We study the full contributions at the leading order(LO) and QCD next-to-leading order(NLO) to the cross section of the \eewwbb process in the standard model(SM) at the ILC. In dealing the resonance problem we adopted the complex mass…
We present for the first time the complete three-loop mixed electroweak-QCD ($\mathcal{O}(\alpha\alpha_s)$) corrections for the decay channel $H \to \gamma\gamma$, by implementing three different on-shell $\alpha$ schemes in computing the…
We compute the three-loop QCD corrections to the massive quark-anti-quark-photon form factors $F_1$ and $F_2$ in the large-$N_c$ limit. The analytic results are expressed in terms of Goncharov polylogarithms. This allows for a…
We present O(alpha_s^2) corrections to the decay t-->bW in the limit of a very large top quark mass, m_t >> m_W. We find that the O(alpha_s^2) effects decrease the top quark decay width Gamma_t by about 2%: Gamma_t =…
The decay width of $Z^0$ to $B_c$ meson is evaluated at the next-to-leading order(NLO) accuracy in strong interaction. Numerical calculation shows that the NLO correction to this process is remarkable. The quantum…
For the first time the next-to-leading-order electroweak corrections to the full off-shell production of two top quarks that decay leptonically are presented. This calculation includes all off-shell, non-resonant, and interference effects…
We compute the one-loop QCD amplitudes for the decay of an off-shell vector boson with vector couplings into a quark-antiquark pair accompanied by two gluons keeping, for the first time, all orders in the number of colours. Together with…
The three-loop non-mixing contributions to the anomalous dimension of the leading order quark pair production current in non-relativistic QCD are computed. It is demonstrated that the renormalization procedure can only be carried out…
One of the most challenging open problems in heavy quarkonium physics is the double charm production in $e^+e^-$ annihilation at B factories. The measured cross section of $e^+ e^- \to J/\psi + \eta_c$ is much larger than leading order (LO)…
We present the NNLO QCD virtual corrections for qurak-antiquark -> gluon photon, quark-antiquark -> photon photon and the NNLO QED virtual corrections for electron positron -> photon photon and all processes related by crossing symmetry. We…
In this paper, we study the next-to-next-to-leading-order (NNLO) QCD corrections for the process $e^+e^- \to J/\psi+J/\psi$ at the $B$ factories. By including the NNLO corrections, the cross section turns negative due to the poor…