[Jlab-seminars] Theory Center Seminar

[Mary Fox]

Theory Center Seminar
Wed., May 17, 2017
2:00 p.m. (coffee at 1:45 p.m.)
CEBAF Center, Room F224

Carlos Granados
Christopher Newport University*

* *Hyperon Transition Form Factors

*
The electromagnetic form factors for the transition of a Sigma to a 
Lambda hyperon at low energy
are calculated using dispersion theory. In this approach we consider the 
two pion cut of the
transition, in which the imaginary part of the form factors is written 
as a direct product of the
two-pion-Sigma-Lambda amplitudes and the complex conjugate of the pion 
form factor. A
procedure combining dispersion theory and (NLO) baryon chiral 
perturbation theory is also used in
computing the two-pion-Sigma-Lambda amplitudes including a two pion 
rescattering contribution.
It is also found that the inclusion of decuplet baryons in the 
intermediate state of the transition
is necessary in order to obtain reasonable results consistent with 
overall expectations. Through
this approach, the electric transition form factor remains very small 
while the magnetic form factor
depends strongly on a not well defi
ned low-energy constant of the NLO 
Lagrangian. The predictive
power of this approach will be enhanced by significantly constraining 
this constant from a measurement
of the magnetic transition radius. Such a measurement can be performed 
at the future Facility
for Antiproton and Ion Research (FAIR).
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