arXiv subjects

Norberto Scoccola

Publications and source records attributed to Norberto Scoccola.

3 recordsLinked to original sources

arXiv2026

Leading order quark-antiquark-W-boson vertex in the presence of a magnetic field

We compute the leading order modification to the quark-antiquark-$W$-boson vertex in the presence of a constant and uniform magnetic field, specifically for the case where the quark and antiquark are the $u$ and $\bar{d}$, respectively. We find the selection rules for transitions where the $u$, $\bar{d}$, and $W$-boson occupy arbitrary Landau levels. We show that, for the particular case where the initial particles each occupy the lowest Landau level, the $W^+$ is also produced in the lowest Landau level with a single polarization aligned with the magnetic field. We also illustrate the general findings by computing the case of transitions between low lying Landau levels and show the correspondence between the polarization vectors for the $W$-boson and the polarization states for the quark and the antiquark.

hep-ph↗

arXiv2026

QED vertex and anomalous magnetic moment in the presence of a magnetic field

We compute the fermion-photon vertex in QED in the presence of a constant and uniform magnetic background up to one-loop order. We show that even at tree-level, the vertex is modified due to the loss of Lorentz invariance induced by the magnetic field, thus breaking into longitudinal and transverse pieces. Moreover, the radiative corrections induce the emergence of a rich tensor structure that includes the anomalous magnetic moments in the transverse, parallel, and mixed transverse/parallel directions. We concentrate on studying one of these anomalous magnetic moment components, the one in the purely transverse direction. We find the selection rules for transitions between a few low-lying Landau levels and show that the amplitudes for transitions from an initial to a final Landau level differ by a sign from the reverse process due to the loss of time reversal invariance induced by the presence of the field. Contrary to the vacuum case, the amplitudes are, in general, complex, and the phase factor can be interpreted in terms of a finite life-time of the decaying state. For the anomalous magnetic moment in the purely transverse direction, transitions between states occupying both the lowest Landau levels are forbidden. Moreover, for the computation of the allowed transitions, we find that it is not necessary to include a photon mass since the magnetic field acts as an infrared regulator.

hep-ph↗

arXiv2013

Deconfinement and chiral restoration within the SU(3) Polyakov--Nambu--Jona-Lasinio and entangled Polyakov--Nambu--Jona-Lasinio models in an external magnetic field

The behavior of the quark condensates at zero chemical potential and finite temperature subject to an external magnetic field is studied within the three flavor Nambu--Jona-Lasinio model with Polyakov loop (PNJL) and its extension, the so-called entangled PNJL model (EPNJL). A comparison with recent lattice QCD data is performed and it is shown that at $T=0$ MeV the light quark condensates are in quantitative agreement. At finite temperature, although there is an overall reasonable agreement with several lattice results, it is shown that in the lattice calculations the effect due to the electric charge quark difference is stronger and the restoration of the $u$ quark chiral symmetry starts at lower temperatures. When considering the EPNJL model with a Polyakov loop scale parameter that depends on the magnetic field, it is possible to obtain an earlier rise of the Polyakov loop with the increase of the magnetic field and due to the entanglement, the inverse magnetic catalysis is found as in the lattice QCD calculations.

hep-ph↗