John Morales

Pion mass effects in the large-n limit of chiral perturbation-theory

We compute the large

A note on the γγ → π0π0 reaction in the 1N expansion of χPT

N

Chiral Symmetry restoration from the hadronic regime

effective action of the

Phenomenology of the new physics coming from 2HDMs to the neutrino magnetic dipole moment

O(N+1)/O(N)

Large-N pion scattering at finite temperature: The f_0(500) and chiral restoration

non-linear sigma model including the effect of the pion mass to order

Chiral symmetry restoration for the large-N pion gas

m^2_{\pi}/f_{\pi}^2

Free Energy of a Large-

. This action is more complex than the one corresponding to the chiral limit not only because of the pion propagators but also because chiral symmetry produce new interactions proportional to

N

m^2_{\pi}/f_{\pi}^2

Pion Gas and Chiral Symmetry Restoration

. We renormalize the action by including the appropriate counter terms and find the renormalization group equations for the corresponding couplings. Then we estudy the unitarity propierties of the scattering amplitudes. Finally our results are applied to the particular case of the linear sigma model and also are used to fit the pion scattering phase shifts.

Contribution to the neutrino magnetic moment coming from 2HDM in presence of magnetic fields

Abstract In this work we present the results of a complete calculation of the γγ → π 0 π 0 amplitude to leading order in the large N approximation ( N being the number of Goldstone bosons) up to order m π 2 F 2 . The amplitude turns to be proportional to that of π + π − → π 0 π 0 . In spite of the fact that this factorization property cannot hold in general (as it was recently pointed out by Morgan and Penington), it appears here since in the large N limit only the I = J = 0 channel contributes to the γγ → π 0 π 0 reaction. Moreover it seems to be a reasonable approximation in this case since it is possible to reproduce, as a prediction, the experimental data starting from a one-parameter fit of the ππ scattering data.