1202.2299 (G. Ramalho et al.)

Valence quark and meson cloud contributions for the gamma* Lambda ->
Lambda* and gamma* Sigma0 -> Lambda* reactions    [PDF]

G. Ramalho, D. Jido, K. Tsushima

We estimate the valence quark contributions for the gamma* Y -> Lambda*
(Y=Lambda, Sigma0) electromagnetic transition form factors. We focus
particularly on the case Lambda*=Lambda(1670) as an analog reaction with gamma*
N -> N(1535). The results are compared with those obtained from chiral unitary
model, where the Lambda* resonance is dynamically generated and thus the
electromagnetic structure comes directly from the meson cloud excitation of the
baryon ground states. The form factors for the case Y=Sigma0 in particular,
depend crucially on the two real phase (sign) combination, a phase between the
Lambda and Lambda* states, and the other, the phase between the Lambda and
Sigma0 radial wave functions. Depending on the combination of these two phases,
the form factors for the gamma* Sigma0 -> Lambda* reaction can be enhanced or
suppressed. Therefore, there is a possibility to determine the phase
combination by experiments.

View original: http://arxiv.org/abs/1202.2299