Related papers: $K \to 2 \pi$ Decay in the Nambu-Jona-Lasinio Mode…
We use a twice-subtracted partial-wave dispersion relation in the elastic unitarity approximation for final-state interactions to study the amplitude for the delta I = 1/2 CP-conserving weak process K+spurion->pi+pi. We use a simple…
The \Delta I = 3/2 K to pi pi decay amplitude is calculated on RBC/UKQCD 32^3 times 64, L_s=32 dynamical lattices with 2+1 flavours of domain wall fermions using the Dislocation Suppressing Determinant Ratio and Iwasaki gauge action. The…
The Delta I = 3/2 K to Pi Pi decay amplitude is calculated on RBC/UKQCD 32^3 x 64, L_s=32 dynamical lattices with 2+1 flavors of domain wall fermions using the DSDR and Iwasaki gauge action. The calculation is performed with a single pion…
The decay widths of $V \to K(\pi) l \bar{\nu}_l $ are calculated within the Nambu--Jona-Lasinio model, where $V=K^*, \rho, \omega, \phi$ and $l=\mu, e$. The results are obtained using the previously fixed model parameters without…
The weak leptonic decays $\pi^\pm\to\mu^\pm\nu_{\mu}(\bar{\nu}_{\mu}), \pi^\pm\to e^\pm\nu_e(\bar{\nu}_{e}), K^\pm\to\mu^\pm\nu_{\mu}(\bar{\nu}_{\mu})$ and $K^\pm\to e^\pm \nu_e(\bar{\nu}_{e})$ are investigated within the framework of the…
The transition amplitude for $\pi K$ scattering is evaluated within the SU(3) Nambu--Jona-Lasinio model. Ordering terms according to the expansion in $1/N_c$ leads to a box-like diagram, $t$ channel diagrams that admit scalar isoscalar…
Decays of scalar mesons $K^*_0(800) \to K\pi$ and $K^*_0(1430) \to K\pi, K \eta, K \eta', K_1 \pi$ are described in the extended $U(3 ) \times U(3)$ Nambu - Jona-Lasinio chiral quark model. The obtained results are in satisfactory agreement…
We quantify the important effect of strong final state interactions in the weak $K\to 2\pi$ amplitudes, using the measured $\pi$-$\pi$ phase shifts with J=0 and $I=0,2$. The main results of this analysis, with their implications for…
We present a novel framework for analyzing unstable composite particles using Green's functions and dispersion relations. As an illustrative example, we explore the $\rho$ vector meson decay process $\rho\to\pi\pi$ within the Nambu -- Jona…
The branching fraction of the decay $\tau \to K^{-} \eta \nu_{\tau}$ has been calculated by using the extended Nambu-Jona-Lasinio model taking into account the meson interaction in the final state. The contact term and the channel with the…
The weak decay of the kaon to two pions is studied within the NJL Model. Using the standard effective weak Hamiltonian, both the decay amplitude arising from an intermediate state \sigma-meson and the direct decay amplitude are calculated.…
We report a direct lattice calculation of the $K$ to $\pi\pi$ decay matrix elements for both $\Delta I=1/2$ and $3/2$ channels on 2+1 flavor, domain wall fermion, $16^3\times32$ lattices with zero $\pi\pi$ relative momentum and $m_\pi=420$…
Non-leptonic hyperon weak decays are investigated in the SU(3) Skyrme model. We use a collective coordinate scheme, following the approach in which the symmetry breaking terms in the strong effective action are diagonalized exactly. To…
We present our result for the $K\to\pi\pi$ decay amplitudes for both the $\Delta I=1/2$ and $3/2$ processes with the improved Wilson fermion action. In order to realize the physical kinematics, where the pions in the final state have finite…
We study the scaling with the number of colours, $N_c$, of the weak amplitudes mediating kaon mixing and decay. We evaluate the amplitudes of the two relevant current-current operators on the lattice for $N_c=3-7$. We conclude that the…
Because of the small size of the ratio A_2/A_0 of the I=2 to I=0 K -> pipi decay amplitudes (the Delta I=1/2 rule) the effects of electromagnetism on A_2 may be a factor of 20 larger than given by a naive O(alpha) estimate. Thus, if future…
We calculate $\Delta I = 3/2$ kaon decay matrix elements using domain wall fermions and the DBW2 gauge action at one coarse lattice spacing corresponding to $a^{-1} = 1.3$ GeV. We employ the Lellouch and L\"uscher formula and its extention…
We report a direct lattice calculation of the $K$ to $\pi\pi$ decay matrix elements for both the $\Delta I=1/2$ and 3/2 amplitudes $A_0$ and $A_2$ on 2+1 flavor, domain wall fermion, $16^3\times32\times16$ lattices. This is a complete…
We examine the uncertainties involved in the off-mass-shell extrapolation of the $K\rightarrow \pi\pi$ decay amplitude with emphasis on those aspects that have so far been overlooked or ignored. Among them are initial-state interactions,…
We estimate nonfactorizable 1/$N_c$ contributions in the $K\rightarrow 2\pi$ amplitudes using the approach proposed in our previous work. It is demonstrated that for the conventional (nonpenguin) operators these contributions are close in…