[Jlab-seminars] Theory Center Seminar

[Mary Fox]

THEORY CENTER SEMINAR
Monday, Nov. 21, 2011
1:00 p.m. (coffee at 12:45 p.m.)
CEBAF Center, Room L104


Carlos Schat
Instituto de Fisica de Buenos Aires, CONICET and
Universidad de Buenos Aires, Argentina

*Sigma Meson Width, Pion Polarizabilities and Roy-Steiner Equations *

We construct the Roy-Steiner equations for pion Compton scattering. The 
Roy-Steiner equations
respect analyticity and unitarity requirements, gauge invariance, as 
well as crossing symmetry.
To suppress the dependence on the high-energy region, we consider once- 
and twice-subtracted
versions of the equations, where the subtraction constants are 
identified with dipole and
quadrupole pion polarizabilities. As an application we study the 
$\gamma\gamma\to\pi\pi$ partial waves
by a Muskhelishvili-Omn\`es representation with finite matching point, 
and discuss the consequences
for the two-photon coupling of the $\sigma$ resonance and its relation 
to pion polarizabilities.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://mailman.jlab.org/pipermail/jlab-seminars/attachments/20111118/fccc2be7/attachment.html