https://doi.org/10.1140/epjc/s10052-015-3715-z
Regular Article - Theoretical Physics
Form factors of the isovector scalar current and the
scattering phase shifts
1
Groupe de Physique Théorique, IPN (UMR8608), Université Paris-Sud 11, Orsay, France
2
Instituto de Física Corpuscular (IFIC), Centro Mixto CSIC-Universidad de Valencia, Valencia, Spain
* e-mail: moussall@ipno.in2p3.fr
Received:
20
July
2015
Accepted:
2
October
2015
Published online:
13
October
2015
A model for S-wave scattering is proposed which could be realistic in an energy range from threshold up to above 1 GeV, where inelasticity is dominated by the
channel. The T-matrix, satisfying two-channel unitarity, is given in a form which matches the chiral expansion results at order
exactly for the
,
amplitudes and approximately for
. It contains six phenomenological parameters. Asymptotic conditions are imposed which ensure a minimal solution of the Muskhelishvili–Omnès problem, thus allowing one to compute the
and
form factor matrix elements of the
scalar current from the T-matrix. The phenomenological parameters are determined such as to reproduce the experimental properties of the
,
resonances, as well as the chiral results of the
and
scalar radii, which are predicted to be remarkably small at
. This T-matrix model could be used for a unified treatment of the
final-state interaction problem in processes such as
,
, or the
initial-state interaction in
.
© SIF and Springer-Verlag Berlin Heidelberg, 2015