5 papers
Unstable particles, gauge invariance and the Delta^{++} resonance parameters
G. Lopez Castro, A. Mariano
The elastic and radiative pion(+)-proton scattering are studied in the framework of an effective Lagrangian model for the Delta^{++} resonance and its interactions. The finite widt…
Analytical Behaviour of Positronium Decay Amplitudes
G. Lopez Castro, J. Pestieau, C. Smith +1
Positronium annihilation amplitudes that are computed by assuming a factorization approximation with on-shell intermediate leptons do not exhibit good analytical behaviour. Using d…
Parapositronium Decay and Dispersion Relations
G. Lopez Castro, J. Pestieau, C. Smith +1
Positronium decay rates are computed at the one-loop level, using convolution-type factorized amplitudes. The dynamics of this factorization is probed with dispersion relations, sh…
Binding energy corrections in positronium decays
G. Lopez Castro, J. Pestieau, C. Smith
Positronium annihilation amplitudes that are computed by assuming a factorization approximation with on-shell intermediate leptons, do not exhibit good analytical behavior. We prop…
Arithmetic and the standard electroweak theory
G. Lopez Castro, J. Pestieau
We propose the relations 1/e - e =3 and tan(2theta_W)=3/2, where e is the positron charge and theta_W is the weak angle. Present experimental data support these relations to a very…