1202.5399 (Gauhar Abbas et al.)

The $Kπ$ form factors from Analyticity and Unitarity    [PDF]

Gauhar Abbas, B. Ananthanarayan, I. Caprini, I. Sentitemsu Imsong

Analyticity and unitarity techniques are employed to obtain bounds on the
shape parameters of the scalar and vector form factors of semileptonic $K_{l3}$
decays. For this purpose we use vector and scalar correlators evaluated in
pQCD, a low energy theorem for scalar form factor, lattice results for the
ratio of kaon and pion decay constants, chiral perturbation theory calculations
for the scalar form factor at the Callan-Treiman point and experimental
information on the phase and modulus of $K\pi $ form factors up to an energy
$\tin=1 {\rm GeV}^2$. We further derive regions on the real axis and in the
complex-energy plane where the form factors cannot have zeros.

View original: http://arxiv.org/abs/1202.5399