We investigate the structure of the scalar mesons f0(975) and a0(980) within realistic meson-exchange models of the ππ and πη interactions. Starting from a modified version of the Jülich model for ππ scattering we perform an analysis of the pole structure of the resulting scattering amplitude and find, in contrast to existing models, a somewhat large mass for the f0(975) (mf0 = 1015 MeV, Γf0 = ...

A separable potential formalism is used to describe the ππ and KK interactions in the I G (J P C) = 0 + (0 ++) states in the energy range from the ππ threshold up to 1.4 GeV. Introduction of relativistic propaga-tors into a system of Lippmann-Schwinger equations leads to a very good description of the data (χ 2 = 0.93 per one degree of freedom). Three poles are found in this energy region: f 0 ...

Recent results from CLEO on B → Kπ indicate that the phase γ may be substantially different from that obtained from other fit to the KM matrix elements in the Standard Model. We show that γ extracted usingB → Kπ, ππ is sensitive to new physics occurring at loop level. It provides a powerful method to probe new physics in electroweak penguin interactions. Using effects due to anomalous gauge cou...

The amplitude for the anomalous transitions γπ → ππ is analyzed within Chiral Perturbation Theory including electromagnetic interactions. The presence of a t-channel one-photon exchange contribution induces sizeable O(e2) corrections which enhance the cross-section in the threshold region and bring the theoretical prediction into agreement with available data. In the case of the crossed reactio...

K → ππ decays are investigated in the framework of the SU (2) L × U (1) gauge theory of J = 0 mesons proposed in [1], to which is added an interaction between mesons respecting the two symmetries generally attributed to strong interactions, flavour symmetry and parity conservation. It is shown that the damping of the K + → π + π 0 amplitude with respect to the ones of K s → ππ results from a ca...

We derive dispersion relations for K → ππ decay, using the Lehmann-Symanzik-Zimmermann formalism, which allows the analytic continuation of the amplitudes with respect to the momenta of the external particles. No off-shell extrapolation of the field operators is assumed. We obtain generalized Omnès representations, which incorporate the ππ and πK S-wave phase shifts in the elastic region of the...

We derive dispersion relations for K → ππ decay, using the LehmannSymanzik-Zimmermann formalism, which allows the analytic continuation of the amplitudes with respect to the momenta of the external particles. No off-shell extrapolation of the field operators is assumed. We obtain generalized Omnès representations, which incorporate the ππ and πK S-wave phase shifts in the elastic region of the ...

Recent results from CLEO on B → Kπ indicate that the phase γ may be substantially different from that obtained from other fit to the KM matrix elements in the Standard Model. We show that γ extracted usingB → Kπ, ππ is sensitive to new physics occurring at loop level. It provides a powerful method to probe new physics in electroweak penguin interactions. Using effects due to anomalous gauge cou...

Final state interactions in the S–wave ππ system (I=0,2) are reexamined on the basis of the Omnès-Muskhelishvili equation and the coupled channel formalism. The contributions to the pion scalar form factor from ρ and f 2 (1270) exchange in the t–channel and from the f 0 (980) s–channel resonance are separately evaluated and the role of the nontrivial polynomial in the Omnès function in a couple...