Magnetic corrections to the pion electromagnetic form factor
Ardiles Díaz, Mauricio Javier
In this work, we investigate the effect of a magnetic field background to the pion electromagnetic form factor. We face this problem through the Finite Energy Sum Rule (FESR) program, where a suitable current correlation function, built of Quantum Chromodynamics (QCD) degrees of freedom, is used to establish a map to the hadronic world and then extracting then the form factor. The magnetic field effects are encoded in the perturbative QCD side through the fermionic propagator in the presence of a magnetic field background, known as Schwinger propagator. We analyze the strong and weak magnetic field limits. For the weak field limit, the current correlator can be written as an expansion in powers of eB. We restricted the calculation to first order in eB leading to anomalous results which must be improved. However, for the strong field limit, we applied the Landau level expansion of the Schwinger propagator and consider up to the first Landau level leading to a proper FESR. The numerical results show that a strong magnetic field increases the pion form factor several times. For example, for a fixed magnetic field of eB = 1 GeV2 the pion form factor can be four times larger. This result affects directly the electron-pion scattering cross section which is also connected to the Sullivan process, leading to potential effects of the magnetic field on collider experiments.