Recent developments in rare kaon decays

We discuss issues in rare and radiative kaon decays. The interest is to extract useful short-distance information and uncover underlying dynamics. We emphasize channels where either we can understand non-perturbative aspects of QCD or there is a chance to test the Standard Model.Comment: Invited minireview for Modern Physics Letters A (MPLA), 15 pages, 9 figures, usepackages epsf,colo

Electromagnetic penguin operators and direct CP violation in K --> pi l^+ l^-

Supersymmetric extensions of the Standard Model predict a large enhancement of the Wilson coefficients of the dimension-five electromagnetic penguin operators affecting the direct CP violation in K_L --> pi^0 e^+ e^- and the charge asymmetry in K^\pm --> pi^\pm l^+ l^-. Here we compute the relevant matrix elements in the chiral quark model and compare these with the ones given by lattice calculationsComment: 12 pages, JHEP style, gluonic corrections to B_T adde

K→πℓ+ℓ−K \rightarrow \pi \ell^+ \ell^- form factor in the Large-Nc_c and cut-off regularization method

Bardeen-Buras-G\'{e}rard have proposed a large N$_c$ method to evaluate hadronic weak matrix elements to attack for instance the determination of the $\Delta I= \frac{1}{2}$-rule and $\mathrm{Re}(\frac{\epsilon'}{\epsilon})$. Here we test this method to the determination of the form factor parameters $a_+$ and $b_+$ in the decays $K^+ \rightarrow \pi^+ \ell^+ \ell^-$ and $K_S \rightarrow \pi ^0 \ell^+ \ell^-$. The results are encouraging: in particular after a complete treatment of Vector Meson Dominance (VMD).Comment: 9 pages, two columns, 5 figure

A search for Z' in muon neutrino associated charm production

In many extensions of the Standard Model the presence of an extra neutral boson, Z', is invoked. A precision study of weak neutral-current exchange processes involving only second generation fermions is still missing. We propose a search for Z' in muon neutrino associated charm production. This process only involves Z' couplings with fermions from the second generation. An experimental method is thoroughly described using an ideal detector. As an application, the accuracy reachable with present and future experiments has been estimated.Comment: 13 pages, 3 figures, late

Radiative Non-Leptonic Kaon Decays

We investigate to what extent DA$\Phi$NE will be able to test the Standard Model in the confinement regime with radiative kaon decays. We concentrate on processes which can be detected at DA$\Phi$NE and we review briefly those decays where only upper limits can be expected. The Standard Model predictions for these decays are analyzed in the framework of chiral perturbation theory.Comment: 41 pages, latex file, 10 figures added in a separate uufil

Kaon decay interferometry as meson dynamics probes

We discuss the time dependent interferences between $K_L$ and $K_S$ in the decays in $3\pi$ and $\pi\pi\gamma$, to be studied at interferometry machines such as the $\phi$-factory and LEAR. We emphasize the possibilities and the advantages of using interferences, in comparison with width measurements, to obtain information both on $CP$ conserving and $CP$ violating amplitudes. Comparison with present data and suggestions for future experiments are made.Comment: 15 pages, in RevTex, Report INFNNA-IV-93-31, UTS-DFT-93-2