0000000000458745
AUTHOR
Juan Esteban Palomar Burdeus
Decay of axial-vector mesons into VP and P gamma
We propose a phenomenological Lagrangian for the decay of the SU(3) nonets of the axial-vector mesons of $J^{PC}=1^{+-},1^{++}$ into a vector meson and a pseudoscalar constructed with tensor fields for the vector and axial-vector mesons. The formulation leads to a good reproduction of the different decay branching ratios and assuming vector meson dominance (VMD) it also leads to good results for the radiative decay of the $a_1$ into pion and photon, and in agreement with the structure proposed in the chiral tensor formulation of radiative decay of axial-vector mesons. The two SU(3) parameters and the mixing angle of $K_{1A}$ and $K_{1B}$ needed to give the physical $K_1(1270)$ and $K_1(1400…
Chiral loops and VMD in the V -> P P gamma decays
We evaluate radiative decays of rho and omega going to two neutral mesons, pi(0)pi(0) and pi(0)eta. We use the sequential vector decay mechanisms in addition to chiral loops and rho-omega mixing. The chiral loops are obtained using elements of UchiPT successfully applied in the study of meson-meson interactions up to 1.2 GeV. The chiral loops are found very important in the case of the rho --> pi(0)pi(0)gamma decay and small in the other cases. A good agreement with present measurements of rho --> pi(0)pi(0)gamma and omega --> pi(0)pi(0)gamma is obtained and predictions are made for the other decays where the rates obtained are rather small.
Meson exchange in the weak decay of Lambda hypernuclei and the Gamma(n)/Gamma(p) ratio
We take an approach to the Lambda non-mesonic weak decay in nuclei based on the exchange of mesons. The one pion and one kaon exchange are considered, together with the exchange of two pions, either correlated, leading to an important scalar-isoscalar exchange (sigma-like exchange), or uncorrelated (box diagrams). Extra effects of omega exchange in the scalar-isoscalar channel are also considered. Constraints of chiral dynamics are used to generate these exchanges. A drastic reduction of the OPE results for the Gamma_n/Gamma_p ratio is obtained and the new results are compatible with all present experiments within errors. The absolute rates obtained for different nuclei are also in good agr…
Pion and Kaon Vector Form Factors: a Chiral Unitary Approach
The pion and kaon coupled-channel vector form factors are described by making use of the resonance chiral Lagrangian results together with a suitable unitarization method in order to take care of the final state interactions. A very good reproduction of experimental data is accomplished for the vector form factors up to s√≤1.2 GeV and for the ππ P-wave phase shifts up to s√≤1.5 GeV.