Related papers: Soft photon theorem in QCD with massless quarks
We review the state-of-the-art knowledge of IR singularities in multileg QCD amplitudes, identifying the key reasons for the remarkable simplicity of the soft anomalous dimension. We then present a novel strategy to compute this quantity…
We describe the calculation of the three-loop QCD corrections to quark and gluon form factors. The relevant three-loop Feynman diagrams are evaluated and the resulting three-loop Feynman integrals are reduced to a small set of known master…
In this letter we show that the soft behaviour of photons and graviton amplitudes, after projection, can be determined to infinite order in soft expansion via ordinary on-shell gauge invariance. In particular, as one of the particle's…
In this paper we consider the matching coefficient of the vector current between Quantum Chromodynamics (QCD) and Non-Relativistic QCD (NRQCD) to three-loop order in perturbation theory. We evaluate the fermionic corrections containing a…
We analytically compute all four-loop QCD corrections to the photon-quark and Higgs-gluon form factors involving a closed massless fermion loop. Our calculation of non-planar vertex integrals confirms a previous conjecture for the…
The quark contribution to the free energy of a hot quark-gluon plasma is calculated to leading order in hard-thermal-loop (HTL) perturbation theory. This method selectively resums higher order corrections associated with plasma effects,…
We present a QCD study of fragmentation processes for light and heavy quarks in the semi-inclusive region of large x. Large logarithmic terms, due to soft-gluon radiation, are evaluated and resummed to all perturbative orders in the QCD…
We study the leading log infrared behavior of electroweak corrections at TeV scale energies, that will be reached by next generation of linear colliders (NLC). We show that, contrary to what happens at typical LEP energies, it is not…
We compute corrections to the hard thermal (or dense) loop photon polarization tensor associated to a small mass $m$ of the fermions of an electromagnetic plasma at high temperature $T$ (or chemical potential $\mu$). To this aim we use the…
We calculate the three-loop soft function for the production of an electroweak boson (Higgs, $\gamma$, $W^\pm$, $Z$) with large transverse momentum at a hadron collider. It is the first time a soft function for a three-parton process is…
We discuss the reactions $\pi p \to \pi p$ and $\pi p \to \pi p \gamma$ from a general quantum field theory (QFT) point of view, describing these reactions in QCD and lowest relevant order of electromagnetism. We consider the pion-proton…
The contribution of the QCD pomeron to the processes: e+e- to e+e- J/psi J/psi and e+ e- to e+ e- hadrons (with tagged electrons) is discussed. We focus on reactions which occur via photon-photon collisions, with virtual photons coming from…
In general line with our first work [Yu.A. Markov, M.A. Markova, Nucl. Phys. A 770 (2006) 162] within the framework of semiclassical approximation a general theory for the scattering processes of soft (anti)quark excitations off hard…
An improved generalized suppression factor for gluon emission off a heavy quark is derived within perturbative QCD, which is valid for the full range of rapidity of the radiated gluon and also has no restriction on the scaled mass of the…
Based on the principle of the Lorentz covariance the transition matrix elements from an off-shell photon state to the vacuum are decomposed into the light-cone photon DAs, in which only two transversal DAs survive in the on-shell limit. The…
B->gamma e nu transitions have recently been studied in the framework of QCD factorization. The attractiveness of this channel for such an analysis lies in the fact that, at least in the heavy quark limit, the only hadron involved is the B…
We calculate QED corrections to the semileptonic decays $H_1 \to H_2\ell^+\ell^-$ where $\ell=e, \mu$ and $H_{1,2}$ are hadrons. The soft and/or collinear divergences are regulated in a gauge-invariant manner and demonstrably cancel,…
QED gauge invariance, when combined with analyticity, leads to constraints on the low energy end of the emitted photon spectra. This is known as Low's theorem. It is shown that the Ore-Powell result, as well as further developments for the…
Productions of soft photon with low transverse momenta in high-energy hadron-hadron collisions and $e^+$-$e^-$ annihilations indicate that they are consistently produced in excess of what are predicted by electromagnetic bremsstrahlung when…
Factorization theorems in soft-collinear effective theory at subleading order in power counting involve ``radiative jet functions'', defined in terms of matrix elements of collinear fields with a soft momentum emitted from inside the jet.…