Related papers: The $\Delta I = 1/2$ Selection Rule

The use of G-parity boundary conditions to compute Delta I = 1/2, K to pi pi decays is reviewed and a method to consistently treat both the pions and kaon in full QCD proposed. This approach creates a physical, final-state, pion momentum…

We have used domain wall fermions to calculate $K \to \pi$ and $K \to 0$ matrix elements which can be used to study the $\Delta I = 1/2$ rule for K decays in the Standard Model. Nonlinearities in the $\Delta I = 3/2$ matrix elements due to…

We present preliminary results for the $\Delta I = 3/2$ 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 an extention of the…

The CP conserved non leptonic $K\to \pi \pi \pi$ decays are discussed within the chiral quark model, including chiral perturbation theory corrections. All amplitudes are parameterized in terms of quark and gluon condensate and the…

Non-leptonic kaon decays are often described through an effective chiral weak Hamiltonian, whose couplings ("low-energy constants") encode all non-perturbative QCD physics. It has recently been suggested that these low-energy constants…

This thesis presents the setup and results of numerical calculation of hadronic matrix elements of Delta S=1 weak operators, with the aim of studying the Delta I=1/2 rule and direct CP violation. Such study provides a useful comparison of…

We report on recent advances at understanding the $\Delta I= 1/2$ rule for kaons. We get reasonable matching between short-- and long--distances for scales between between 0.6 and 1.0 GeV and reproduce the $\Delta I=1/2$ rule huge…

A recently proposed strategy to quantify the role of the charm quark mass in the $\Delta I=1/2$ rule is reviewed. Results for the low-energy couplings of the $\Delta S=1$ chiral effective Hamiltonian in a theory with a light charm quark…

The mass spectra of nucleon resonances with spin 1/2, 3/2, and 5/2 are systematically studied in the constituent quark model with meson-quark coupling, which is inspired by the spontaneous breaking of chiral symmetry of QCD. The meson-quark…

By describing strong interactions between hadrons via a relativistic supermultiplet scheme and regarding weak interactions as a perturbation thereof, we derive expressions for nonleptonic weak decay amplitudes in terms of constituent quark…

Violations of the $\Delta$I=1/2 rule are investigated in the nonmesonic weak hypernuclear decay using a weak $\Lambda$N$\to$NN transition potential based on meson exchange. While the weak $\Delta$I=3/2 matrix elements of baryons with…

The isospin I=0 and I=1 kaon-nucleon $S$, $P$, $D$, $F$ wave phase shifts are studied in the chiral SU(3) quark model by solving the resonating group method (RGM) equation. The calculated phase shifts for different partial waves are in…

In kaon decay, electromagnetic radiative corrections can generate shifts in the apparent Delta I = 3/2 amplitude of order alpha A_0/A_2 ~ 22 alpha. In order to know the true Delta I = 3/2 amplitude for comparison with lattice calculations…

The $K\to\pi\pi$ system is analyzed in the chiral limit within the Standard Model. We discuss how to connect the short-distance running in the $|\Delta S|=1$ case to the matrix-elements calculated in a low-energy approximation in a…

We review the status of recent calculations by the RBC-UKQCD collaboration of the complex amplitude $A_2$, corresponding to the decay of a kaon to a two pion state with total isospin 2. In particular, we present preliminary results from two…

We explore application of the domain wall fermion formalism of lattice QCD to calculate the $K\to\pi\pi$ decay amplitudes in terms of the $K\to\pi$ and $K\to 0$ hadronic matrix elements through relations derived in chiral perturbation…

We present a new calculation of long-distance contributions to the K --> pi pi amplitudes using the 1/N_c expansion within the framework of chiral perturbation theory. Along these lines we compute the chiral loop corrections to the…

We make an attempt to clarify the role of the annihilation or "penguin" mode in the description of the $K\rightarrow\pi\pi$ decay within the Standard Model. The attention is concentrated on new operators in the effective $\Delta S=1$…

A consistent census of penguins in the Delta I = 1/2 rule is taken from the eta0 pole contribution to the radiative KL to gamma gamma, KS to pi0 gamma gamma and K+ to pi+ gamma gamma decay modes. We briefly comment on its impact for KL to…

Using constituent quark model constraints we calculate the gluon and sea content of pions solely in terms of their valence density and the known sea and gluon densities of the nucleon. The resulting small-x predictions for g^{pi}(x,Q^2) and…