arXiv subjects

Urs Buergi

Publications and source records attributed to Urs Buergi.

2 recordsLinked to original sources

arXiv1996

Charged Pion-Pair Production and Pion Polarizabilities to two Loops

We evaluate the amplitude for gamma gamma --> pi^+ pi^- to two loops in the framework of chiral perturbation theory.The three new coupling constants that enter the result at this order in the low-energy expansion are estimated via resonance saturation. We discuss in addition the crossed channel processes gamma pi^+ --> gamma pi^+ - in particular the charged pion polarizabilities - to the same accuracy. The predictions are compared with available experimental information.

hep-ph↗

arXiv1996

Charged Pion Polarizabilities to two Loops

We evaluate the electric and magnetic polarizabilities of charged pions in the framework of chiral perturbation theory at next-to-leading order. This requires a two-loop evaluation of the Compton amplitude near threshold. We estimate the two new low-energy constants which enter the chiral expansion at this order with resonance saturation. The numerical results are compared with presently available experimental information.

hep-ph↗