Related papers: K_L -> pi pi e e in Chiral Perturbation Theory
Calculations of eta->pi^0 pi^0 gamma gamma decay in Generalized chiral perturbation theory are presented. Tree level and next-to-leading corrections are involved. Sensitivity to the violation of the standard counting is discussed.
The status of chiral perturbation theory in the meson sector is illustrated with several topical examples. The longtime discrepancy between theory and experiment for the charged pion polarizabilities has now been resolved in favour of the…
We review our recent work on unitarization and chiral perturbation theory both in the $\pi\pi$ and the $\pi N$ sectors. We pay particular attention to the Bethe-Salpeter and Inverse Amplitude unitarization methods and their recent…
We observe 441 K_{L} -> e^{+} e^{-} e^{+} e^{-} candidate events with a background of 4.2 events and measure B(K_{L} -> e^{+} e^{-} e^{+} e^{-}) = (3.72 \pm 0.18(stat) \pm 0.23(syst)) \times 10^{-8} in the KTeV/E799II experiment at…
The very clean theoretical predictions for the rare decays K --> pi nu nu_bar and KL --> pi0 l+ l- are reviewed, and their various theoretical inputs summarized. The less favorable situation for KL --> mu+ mu- is also commented.
We discuss $\pi\pi$ scattering in the framework of chiral perturbation theory. In particular, we recall the predictions made some time ago for the threshold parameters and for the phase shift difference $\delta_0^0-\delta_1^1$.
We present the ingredients for determining $K^{+}\to\pi^{+}\pi^{0}$ matrix elements via the combination of lattice QCD and chiral perturbation theory ($\chi$PT). By simulating these matrix elements at unphysical kinematics, it is possible…
We review the Standard Model predictions of CP violation in kaon decays. We present an elementary introduction to Chiral Perturbation Theory, four--quark effective hamiltonians and the relation among them. Particular attention is devoted to…
I consider some selected topics in chiral perturbation theory (CHPT) as probed at colliders such as DA$\Phi$NE. Emphasis is put on processes involving pions in the isospin zero S-wave which require multi-loop calculations. These include the…
Recent results by the NA48 collaboration on neutral kaons rare decays into the pi+ pi- e+ e- final state are presented. A large CP-violating asymmetry A(K_L)=(13.9+-2.7+-2.0)% has been observed in the K_L to pi+ pi- e+ e- decay. The K_S to…
A short overview of recent progress in describing kaon and pion decays within Chiral Perturbation Theory is presented. Particular attention is devoted to the issues of final-state interactions and isospin breaking in $K \to 2 \pi$, as well…
It is shown that the low energy coefficients of the next-to-leading order (NLO) chiral perturbation theory needed to determine $\Delta I=1/2$, $K\to\pi\pi$ decay amplitudes can be fixed by calculating $K\pi\to\pi$ amplitudes on lattice.…
The importance of rare $K$ decays especially in the context of a kaon unitarity triangle (KUT) is emphasized. The decay $K_L \to \pi^0 \nu \bar \nu$ is theoretically very clean but experimentally extremely challenging. The Standard Model…
Preliminary results for the Dalitz plot distribution of $\eta^\prime\to\eta\pi\pi$ decays in the frameworks of Large-$N_c$ Chiral Perturbation Theory and Resonance Chiral Theory are given. We hope our results to be of some relevance for the…
The recently published E865 data on charged K_e4 decays and Pi-Pi phases are reanalyzed to extract values of the two S-wave scattering lengths, of the subthreshold parameters alpha and beta, of the low-energy constants l3-bar and l4-bar as…
We use both old and new theoretical developments in QCD dispersion relation constraints on the scalar form factor in the decay K --> \pi l \nu_l to obtain constraints on the strange quark mass. The perturbative QCD side of the calculation…
Low lying scalar resonances emerge as a necessary part to adjust chiral perturbation theory to experimental data once unitarity constraint is taken into consideration. I review recent progress made in this direction in a model independent…
We present a calculation of the decays $\eta^{(')}\to\pi^+\pi^-\gamma^{(\ast)}$ at the one-loop level up to and including next-to-next-to-leading order (NNLO) in large-$N_c$ chiral perturbation theory. The numerical evaluation of the…
We evaluate the matrix elements for the radiative kaon decays $K^+ \to l^+\nu_l\gamma$, $l^+ \nu_l l'^+ l'^-$ and $K \to \pi l \nu_l\gamma$ \ ($l,\ l' = e,\mu$) to next-to-leading order in chiral perturbation theory. We calculate total…
We present a concise review of the theoretical status of rare K -> pi nu nubar decays in the standard model (SM). Particular attention is thereby devoted to the recent calculation of the next-to-next-to-leading order (NNLO) corrections to…