Related papers: Two-loop QCD Corrections to the Heavy Quark Form F…
We perform an analysis of the one- and two-loop massive quark form factor in QED in a region expansion, up to next-to-leading power in the quark mass. This yields an extensive set of regional integrals, categorized into three topologies,…
We analytically compute the four-loop QCD corrections for the colour structure $(d_F^{abcd})^2$ to the massless non-singlet quark form factor. The computation involves non-trivial non-planar integral families which have master integrals in…
Two-loop QED corrections with closed fermion loops are calculated for the 1s bound-electron g factor. Calculations are performed to all orders in the nuclear binding strength parameter Z\alpha (where Z is the nuclear charge and \alpha is…
We numerically compute the two-loop QCD corrections to $Z\gamma$ production at the LHC mediated by light- and heavy-quark box loops. The calculation employs the pipeline of refs. arXiv:2407.18051 and arXiv:2510.18801, which performs Monte…
We derive light-cone sum rules for the electromagnetic nucleon form factors including the next-to-leading-order corrections for the contribution of twist-three and twist-four operators and a consistent treatment of the nucleon mass…
We present the computation of the two-loop form factors for diphoton production in the quark annihilation channel. These quantities are relevant for the NNLO QCD corrections to diphoton production at LHC recently presented in…
A summary of the calculation of the color-planar and complete light quark contributions to the massive three-loop form factors is presented. Here a novel calculation method for the Feynman integrals is used, solving general uni-variate…
The method of QCD sum rules has proven to be particularly useful in heavy quark physics, where a small distance scale is provided by the inverse heavy quark mass. We present two new examples for the application of this method to B-physics:…
Calculations of the magnetic dipole, electric quadrupole and Coulomb quadrupole amplitudes for the transition $\gamma N\to \Delta$ are presented both in quenched QCD and with two flavours of degenerate dynamical quarks.
The electromagnetic and gravitational form factors of $\Omega^-$, a spin-3/2 hyperon composed of three $s$ quarks, are calculated by using a covariant quark-diquark approach. The model parameters are determined by fitting to the form…
The soft current describes the factorization behavior of quantum chromodynamics (QCD) scattering amplitudes in the limit of vanishing energy of one of the external partons. It is process-independent and can be expanded in a perturbative…
We obtain the electromagnetic form factors of the nucleon, in the space-like region, using three-point function Finite Energy QCD Sum Rules. The QCD calculation is performed to leading order in perturbation theory in the chiral limit, and…
A method of deriving bounds on the weak meson form factors, based on perturbative QCD, analyticity and unitarity, is generalized in order to fully exploit heavy quark spin symmetry in the ground state $(L=0)$ doublet of pseudoscalar $(B)$…
Two-loop contributions to the electromagnetic form factors are calculated in the kinematic regime close to the fermion-antifermion threshold. The results are presented in an expansion in the velocity $\beta$ of the fermions in the c.m.…
Meson transition amplitudes of the vector, axial-vector, and tensor quark currents are analyzed within dispersion formulation of the constituent quark model. The form factors in the decay region are given by relativistic double spectral…
The electromagnetic form factors of the proton are obtained using a particular realization of QCD in the large $N_c$ limit (${QCD}_{\infty}$), which sums up the infinite number of zero-width resonances to yield an Euler's Beta function…
This talk presents details of the calculation of two-loop corrections to heavy baryon currents containing one heavy quark in leading order of the $1/m_Q$-expansion, i.e. in the limit of Heavy Quark Symmetry (HQS). The calculations lead to…
A method of computing two-loop fermionic contributions to the width of a heavy quark is described. An analytical formula for this effect in the limit of mass of the quark much larger than the decay products is obtained for the first time.…
The three-loop corrections to the potential of two heavy quarks are computed. Analytic results for the most complicated master integrals are presented.
A short review is given of calculations of the pion electromagnetic and transition form factors within the framework of quantum chromodynamics. It is argued that both the perturbative and nonperturbative aspects of the Q^2 dependence of…