相关论文: Analytical evaluation of certain on-shell two-loop…
The partial decay rate of the $Z$ boson into bottom quarks constitutes an important decay channel. This is mainly due to the virtual presence of the top quark in the loop diagrams giving rise to correction factors which are quadratic in the…
We present on the use of on-shell recursion relations. These can be used not only for calculating tree amplitudes, including those with masses, but also to compute analytically the missing rational terms of one-loop QCD amplitudes. Combined…
We present analytical results for the $O(\alpha _s ^2)$ contributions to the functions $\eta _A$ and $\eta _V$ which parameterize QCD corrections to semileptonic $b \to c$ transitions at zero recoil. Previously obtained approximate results…
We use a modified directed path algorithm to study the finite temperature chiral singularities of two color lattice QCD with staggered fermions at strong coupling. Our lattice calculations are done at a fixed finite temperature in the…
The one-loop supersymmetric QCD corrections to the top quark semileptonic decays $t\to b \bar{l} {\nu_l}$ are considered. The corrections are found to reduce the decay width. In the still acceptable parameter space the corrections to the…
A set of recurrence relations for on-shell two-loop self-energy diagrams with one mass is presented, which allows to reduce the diagrams with arbitrary indices (powers of scalar propagators) to a set of the master integrals. The SHELL2…
Analytic structure in the strong coupling constant that emerges for some observables in QCD after duality averaging of renormalization group improved amplitudes is discussed. It is shown that perturbation theory calculations are justified…
The renormalization of the scalar diquark operator and its anomalous dimension is calculated at two-loop order in QCD, enabling higher-order QCD studies of diquarks. As an application of our result, the two-loop diquark anomalous dimension…
In this paper, we present analytical results for the two-loop QCD corrections to the production of two partons or a photon and a parton in hadronic collisions, mediated by loops of massive quarks. These amplitudes involve Feynman integrals…
We study the problem of calculating two-loop three-point diagrams with irreducible numerators (i.e. numerators which cannot be expressed in terms of the denominators). For the case of massless internal particles and arbitrary (off-shell)…
Evaluation of three- and four-point diagrams with massless internal particles and arbitrary external momenta is considered. Exact results for some two-loop diagrams (planar and non-planar three-point contributions and the "double box"…
In this work we extend the $q_T$-subtraction formalism, originally developed for QCD corrections, to the case of mixed QCD$\otimes$QED corrections, and apply it to the fully exclusive calculation of the ${\cal{O}}(\alpha_s\alpha)$…
We investigate a specific set of two-loop self-energy corrections involving squared decay rates and point out that their interpretation is highly problematic. The corrections cannot be interpreted as radiative energy shifts in the usual…
The one loop vertex in QED is calculated in arbitrary covariant gauges as an analytic function of its momenta. The vertex is decomposed into a longitudinal part, that is fully responsible for ensuring the Ward and Ward-Takahashi identities…
We study a recently-proposed approach to the numerical evaluation of multi-loop Feynman integrals using available sector decomposition programs. As our main example, we consider the two-loop integrals for the $\alpha \alpha_s$ corrections…
We present the two-loop master integrals relevant to the ${\mathcal O}(\alpha \alpha_s)$-corrections to the decay $H \rightarrow b \bar{b}$ through a $H t \bar{t}$-coupling. We keep the full dependence on the heavy particle masses, but…
The loop-tree duality (LTD) theorem establishes that loop contributions to scattering amplitudes can be computed through dual integrals, which are build from single cuts of the virtual diagrams. In order to build a complete LTD…
We present analytic results for one-loop radiative corrections to off-shell decay $H^* \rightarrow W^+W^-$ in 't Hooft-Veltman gauge within Standard Model framework. In numerical results, we show off-shell decay rate and its corrections…
Recently, $O(\alpha^3)$ corrections to the muon decay rate and $O(\alpha_s^3)$ to heavy quark decays have been determined by Fael, Sch\"onwald, and Steinhauser. This is the first such perturbative improvement of these important quantities…
We compute the two-loop QCD corrections to the heavy quark form factors in case of the vector, axial-vector, scalar and pseudo-scalar currents up to second order in the dimensional parameter $\epsilon = (4-D)/2$. These terms are required in…