Jun 13 – 17, 2011
Europe/Berlin timezone
Proceedings are now available online at <a href="http://www.slac.stanford.edu/econf/C110613/">eConf</a>

Roy-Steiner equations for $\gamma\gamma\to\pi\pi$

Jun 14, 2011, 3:35 PM
Club 3 (Künstlerhaus)

Club 3


talk Low-Energy Processes Low-Energy Processes


Mr Martin Hoferichter (Bonn University)


Starting from hyperbolic dispersion relations, we present a system of Roy-Steiner equations for pion Compton scattering that respects analyticity and unitarity requirements, gauge invariance, as well as crossing symmetry, and thus all symmetries of the underlying quantum field theory. To suppress the dependence on the high-energy region, we also consider a once- and twice-subtracted version of the equations, where the subtraction constants are identified with dipole and quadrupole pion polarizabilities. We consider the resolution of the $\gamma\gamma\to\pi\pi$ partial waves by a Muskhelishvili-Omn\`es representation with finite matching point, and present the consequences for the two-photon coupling of the $\sigma$-resonance as well as its relation to pion polarizabilities.

Primary authors

Dr Carlos Schat (Buenos Aires University) Prof. Daniel Phillips (Ohio University) Mr Martin Hoferichter (Bonn University)

Presentation materials