Measuring the a0-a2 pion scattering lengths through K→3πK \to 3 \pi decays

We discuss the recent Cabibbo's proposal to measure the pion-pion scattering lengths combination a0-a2 from the cusp effect in the pi0-pi0 energy spectrum at threshold for K+ to (pi0 pi0 pi+) and KL to (pi0 pi0 pi0). We estimate the theoretical uncertainty of the a0-a2 determination at NLO in our approach and obtain that it is not smaller than 5% for K+ to (pi0 pi0 pi+). One gets similar theoretical uncertainties if the neutral KL to (pi0 pi0 pi0) decay data below threshold are used instead. For this decay, there are very large theoretical uncertainties above threshold due to cancellations and data above threshold cannot be used to get the scattering lengths

The role of final state interactions in epsilon'/epsilon

The Standard Model prediction for epsilon'/epsilon is updated, taking into account the chiral loop corrections induced by final state interactions. The resulting value, epsilon'/epsilon = (17\pm 6)\times 10^{-4}, is in good agreement with present measurements.Comment: 3 pages. Invited talk at the 2000 Meeting of the Division of Particles and Fields of the American Physical Society --DPF2000-- (Columbus, Ohio, August 2000

The Standard Model prediction for eps'/eps

We review fundamental aspects of a new Standard Model analysis of eps'/eps which takes into account the strong enhancement induced by final state interactions.Comment: 3 pages, LaTex, uses ws-p10x7.cls. Talk given by E.P. at ICHEP2000, Osaka, July 27-August 2, 200

epsilon'/eps in the Standard Model

We overview the detailed analysis of epsilon'/epsilon within the Standard Model, presented in ref. 1. When all sources of large logarithms are considered, both at short and long distances, it is possible to perform a reliable Standard Model estimate of epsilon'/epsilon. The strong S-wave rescattering of the final pions has an important impact on this observable. The Standard Model prediction is found to be Re(epsilon'/epsilon) =(1.7 +- 0.9)*10^{-3}, in good agreement with the most recent experimental measurements. A better estimate of the strange quark mass would reduce the uncertainty to about 30%.Comment: Talk presented at the International Europhysics Conference on High Energy Physics, July 12-18, 2001,Budapest, Hungar

Heavy Baryons and electromagnetic decays

In this talk I review the theory of electromagnetic decays of the ground state baryon multiplets with oneheavy quark, calculated using Heavy Hadron Chiral Perturbation Theory. The M1 and E2 amplitudes for (S^{*}-> S gamma), (S^{*} -> T gamma) and (S -> T gamma)are separately analyzed. All M1 transitions are calculated up to O(1/\Lambda_\chi^2). The E2 amplitudes contribute at the same order for (S^{*}-> S gamma), while for (S^{*} -> T gamma) they first appear at O(1/(m_Q \Lambda_\chi^2))and for (S -> T gamma) are completely negligible. Once the loop contributions is considered, relations among different decay amplitudes are derived. Furthermore, one can obtain an absolute prediction for the widths of Xi^{0'(*)}_c-> Xi^{0}_c gamma and Xi^{-'(*)}_b-> Xi^{-}_b gamma.Comment: Talk presented at 4^{th} International Conference Hyperons, Charm and Beauty Hadrons Conference, Valencia June 200

Delta M_K and epsilon_K in SUSY at the Next-to-Leading order

We perform a Next-to-Leading order analysis of Delta S=2 processes beyond the Standard Model. Combining the recently computed NLO anomalous dimensions and the B parameters of the most general Delta S=2 effective Hamiltonian, we give an analytic formula for Delta M_K and epsilon_K in terms of the Wilson coefficients at the high energy scale. This expression can be used for any extension of the Standard Model with new heavy particles. Using this result, we consider gluino-mediated contributions to Delta S=2 transitions in general SUSY models and provide an improved analysis of the constraints on off-diagonal mass terms between the first two generations of down-type squarks. Finally, we improve the constraints on R-violating couplings from Delta M_K and epsilon_K.Comment: 20 pages, 1 figure, uses JHEP.cls; the magic numbers in eq. (2.7), previously given in the basis (13) of hep-ph/9711402, are now given in the basis (2.3) of this work. All numerical results are unchange

CP violation in K±→π0π0π±K^{\pm}\to\pi^0\pi^0\pi^{\pm} decay

CP violation leads to a difference between the parameters $g^+$ and $g^-$ describing the energy distributions of the charged pions produced in the $K^+ \to\pi^0 \pi^0 \pi^+$ and $K^- \to \pi^0\pi^0 \pi^-$ decays. We study the difference $(g^+ - g^-)$ as a function of the relative contributions from the QCD-penguin and the electroweak-penguin diagrams. We find that the combination of these contributions in $(g^+ - g^-)$ is very similar to the corresponding one defining the parameter $\epsilon'$ in the $K_L \to 2\pi$ decays. This observation allows a determination of the value of $(g^+ - g^-)$, using data on $\epsilon'$