With the running B, kaon and neutrino physics experiments, flavour physics takes centre stage within today’s particle physics. We discuss the opportunities offered by these experiments in our search for new physics beyond the SM and discuss their complementarity to collider physics. We focus on rare B and kaon decays, highlighting specific observables in an exemplary mode. We also comment on th...

The size of ππ atom in the low lying states is considerably smaller than the radius of atomic screening. Due to that we can neglect this screening calculating the contribution of multi-photon exchanges. We obtain the analytic formula for Coulomb corrections which works with a very good accuracy for the ground state of ππ atom.

The σ meson in a nuclear medium through two pion photoproduction We present theoretical results for (γ, π 0 π 0) and (γ, π ± π 0) production on nucleons and nuclei in the kinematical region where the scalar isoscalar ππ amplitude is influenced by the σ pole. The final state interaction of the pions modified by the nuclear medium produces a spectacular shift of strength of the π 0 π 0 invariant ...

Elastic pion–pion and pion–nucleon scattering are reviewed in the context of chiral perturbation theory. Theoretical results from systematic low–energy expansions to O(p) for ππ and to O(p) for πN are compared with experimental data. Possible future developments are outlined. Talk given at the Workshop on Chiral Dynamics 1997 Mainz, Germany, Sept. 1 5, 1997 To appear in the Proceedings * Work s...

In this contribution, I summarise the studies of the properties of Bose-Einstein condensed systems composed of up to twelve pions or kaons carried out by the NPLQCD collaboration. These investigations have provided precise determination the I=2 ππ and I=1 KK scattering lengths and the first determination of three-hadron interactions from QCD, finding a repulsive threepion interaction of size co...

The scalar – isoscalar ππ phase shifts are analysed using a separable potential model of three coupled channels (ππ , KK and an effective 2π2π system). Model parameters are fitted to two sets of solutions obtained in a recent analysis of the CERN-Cracow-Munich measurements of the πp↑ → π πn reaction on a polarized target. A relatively narrow (90 – 180 MeV) scalar resonance f0(1400− 1460) is fou...

The riddle of the σ is recast in a way that tries to differentiate fact from fiction as a basis for future/further discussion. By doing this, it is hoped that the role of the σ as dominating the ubitiquitous ππ interactions below 1 GeV and its relation to the QCD vacuum can be clarified. In this talk, I will start to answer some of the questions that Lucien Montanet listed in his introduction a...

The role of penguin amplitudes in CP violating B decays is reviewed, emphasizing recent progress in the analysis of electroweak penguin contributions. It is shown how these terms are included in a model-independent manner when measuring the weak phase α in B → ππ using isospin symmetry, and when determining the phase γ from B → Kπ applying flavor SU(3). Uncertainties due to rescattering effects...

We have searched with the KLOE detector for the P and CP violating decay η → ππ in a sample of 1.55 × 10 η’s from the decay φ → ηγ of φ-mesons produced in ee annihilations at DAΦNE. No signal is found. We obtain the upper limit BR(η → ππ)< 1.3×10 at 90% confidence level.

The goal of the DIRAC experiment at CERN (PS212) is to measure the ππ atom lifetime with 10% precision. Such a measurement would yield a precision of 5% on the value of the S-wave ππ scattering lengths combination |a0 − a2|. Based on part of the collected data we present a first result on the lifetime, τ = [