Related papers: Anomalous Sudakov Form Factors
The gauge symmetry of the Standard Model is SU(3)_c x SU(2)_L x U(1)_Y for unknown reasons. One aspect that can be addressed is the low dimensionality of all its subgroups. Why not much larger groups like SU(7), or for that matter, SP(38)…
We show that the resummation of large radiative corrections in QCD processes can be performed both in covariant gauge and in axial gauge. We extend the resummation technique to inclusive processes, concentrating on deeply inelastic…
We present a detailed theoretical analysis of very rare, exclusive hadronic decays of the electroweak gauge bosons V=W, Z from first principles of QCD. Our main focus is on the radiative decays V->M+gamma, in which M is a pseudoscalar or…
Restrictions imposed by gauge invariance in noncommutative spaces together with the effects of ultraviolet/infrared mixing lead to strong constraints on possible candidates for a noncommutative extension of the Standard Model. We study a…
We consider a U(1) gauge theory, minimally coupled to a massless Dirac field, where a higher-derivative term is added to the pure gauge sector, as in the Lee-Wick models. We find that this term can trigger chiral symmetry breaking at low…
We study the first power correction to the heavy electron form factor in QED and show that it factorizes as a derivative operator. We discuss the result in QED with no light fermions, where the first power correction can be written…
Enhanced radiative corrections generated in SUSY extensions of the Standard Model make the fit of the precision data ($Z$-boson decay parameters and $W$-boson mass) worse. This negative effect is washed out for heavy enough squarks due to…
Properties of amplitudes that describe radiative corrections in a bag of heavy fermions bound by the Higgs boson exchange are studied. Classes of amplitudes, in which the large fermion mass is canceled out and hence produces no enhancement…
With the long-standing tension between experiment and Standard-Model (SM) prediction in the anomalous magnetic moment of the muon $a_\mu$ recently reaffirmed by the Fermilab experiment, the crucial question becomes which other observables…
Heavy quark symmetry relations for $B\rightarrow De\bar \nu_e$ and $B\rightarrow D^*e \bar \nu_e$ form factors receive corrections suppressed by powers of the charm quark mass. For small up and down quark massed the leading corrections of…
We evaluate the one-loop fermion self-energy for the gauged Thirring model in (2+1) dimensions, with one massive fermion flavor, in the framework of the causal perturbation theory. In contrast to QED$_3$, the corresponding two-point…
The naive implementation of finite width effects in processes involving unstable particles can violate gauge invariance. For the example of radiative $W$ production and decay, $q\bar q' \to \ell\nu\gamma$, at tree level, it is demonstrated…
The naive fermiophobic scenario is unstable under radiative corrections, due to the chiral-symmetry breaking induced by fermion mass terms. In a recent study, the problem of including the radiative corrections has been tackled via an…
We study strong and radiative decays of excited singly heavy baryons (SHBs) using an effective chiral Lagrangian based on the diquark picture proposed in Ref. [1]. The effective Lagrangian contains a $U_A (1)$ anomaly term, which induces an…
We study perturbative and non-perturbative aspects of heavy-quark fragmentation into hadrons, emphasizing the large-x region, where x is the energy fraction of the detected hadron. We first prove that when the moment index N and the quark…
If the top is very heavy, m_t >> M_Z, the dominant radiative correction effects in all electroweak precision tests can be exactly characterized in terms of two quantities, the rho-parameter and the GIM violating Z -> b bbar coupling. These…
The role of the contribution from the fermion mass term in the axial vector Ward identity in generating the U(1) axial anomaly, both local and global, is elucidated. Gauge invariance requires the fermion to decouple from the gauge field if…
In this work we study the cancellation of non-perturbative anomalies of gravitational theories with gauge group $\mathbb{Z}_k$ in six dimensions. These subtle anomalies require a classification of deformation classes of manifolds with…
We hypothesise that all electroweak symmetry breaking terms such as fermion masses and the W and Z gauge boson masses arise radiatively from just one explicit symmetry breaking term in the Lagrangian. Our hypothesis is motivated by the lack…
We investigate the possibility of Lorentz and CPT violations in the photon sector, of the Chern-Simons form, be induced by radiative corrections arising from the Lorentz and CPT non-invariant fermionic sector of an extended version of QED.…