Related papers: Epsilon'/Epsilon in the Chiral Limit using Large N…

We study the decay $\eta'\to\eta\pi\pi$ in two different chiral invariant approaches: Large-$N_c$ Chiral Perturbation Theory (ChPT) and Large-$N_c$ Resonance Chiral Theory (RChT). We analyze the Dalitz plot and the invariant mass spectra.…

The $K\to\pi\pi$ decay amplitudes are studied within the framework of generalized factorization in which the effective Wilson coefficients are gauge-invariant, renormalization-scale and -scheme independent while factorization is applied to…

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…

We obtain relations between partial-wave amplitudes for pi-N-->pi-N and pi-N-->pi-Delta directly from large N_c QCD. While linear relations among certain amplitudes holding at leading order (LO) in 1/N_c were derived in the context of…

The $pp\to pp\pi^0$ cross section near threshold is computed up to one-loop order including the initial and final state interactions using the hybrid heavy baryon chiral perturbation theory and the counting rule a la Weinberg. With the…

I review the large Nc behavior of light resonances generated from unitarized one-loop Chiral Perturbation Theory. In contrast with the rho or K*, the scalar behavior is at odds with a qqbar "dominant component". In fact, in the light scalar…

The decay Delta^+ --> p gamma is studied in the 1/N_c expansion of QCD. The ratio of the helicity amplitudes is determined to be A_{3/2}/A_{1/2} = \sqrt{3} + O(1/N_c^2). Equivalently, the ratio E2/M1 of the multipole amplitudes is predicted…

We set up a general framework to describe $\pi\pi$ scattering below 1 GeV based on chiral low-energy expansion with possible spin-0 and 1 resonances. Partial wave amplitudes are obtained with the $N/D$ method, which satisfy unitarity,…

We present the scattering lengths for the $\pi K$ processes in the three flavour Chiral Perturbation Theory (ChPT) framework at next-to-next-to-leading order (NNLO). The calculation has been performed analytically but we only include…

We calculate results for K to pi and K to 0 matrix elements to next-to-leading order in 2+1 flavor partially quenched chiral perturbation theory. Results are presented for both the Delta I=1/2 and 3/2 channels, for chiral operators…

We show that in supersymmetric extensions of the Standard Model gluino box diagrams can yield a large Delta(I)=3/2 contribution to s->d+q(bar)+q FCNC processes, which may induce a sizable CP-violating contribution to the I=2 isospin…

We discuss a number of old and new methods for computing $K\to\pi\pi$ amplitudes on the lattice. They all involve a non-perturbative determination of matching coefficients. We show how problems related to operator mixing can be greatly…

The amplitude for the anomalous process gamma pi -> pi pi is evaluated to two loops in the chiral expansion by means of a dispersive method. The two new coupling constants that enter at this order are estimated via sum rules derived from a…

Trace Anomaly Dominance in weak $K$-decays successfully reproduces the $\Delta I = {1\over 2}$ selection rule results, as observed in $K_S \to \pi\pi, K_L \to \pi\pi\pi, K_S \to \gamma\gamma$ and $K_L \to \pi^0 \gamma\gamma$.

We study the renormalization of the DeltaS=1 effective weak Hamiltonian with overlap fermions. The mixing coefficients among dimension-six operators are computed at one loop in perturbation theory. As a consequence of the chiral symmetry at…

We review the present theoretical status of the CP violating ratio epsilon'/epsilon in the Standard Model (SM) and confront its estimates with the most recent data. In particular we review the present status of the most important parameters…

We study the predictions for the direct CP violation parameter epsilon'/epsilon in a class of string-inspired model with non-universal soft A-terms. We show that the non-universality of the A-terms plays an important rule in enhancing the…

The experimental value for the isospin amplitude Re(A_2) in K->pi pi decays has been successfully explained within the Standard Model, both within large N approach to QCD and by QCD lattice calculations. On the other hand in both approaches…

We compute the isospin $I= 0$ and 2 amplitudes for the decay of a kaon into two pions by estimating the relevant hadronic matrix elements in the chiral quark model. The results are parametrized in terms of the quark and gluon condensates…

The near-threshold n p -> d pi0 cross section is calculated in chiral perturbation theory to next-to-leading order in the expansion parameter sqrt{M m_pi}/Lambda_chi. At this order irreducible pion loops contribute to the relevant…