In this note, we clarify a point concerning the power divergence in lattice calculations of ∆I = 1/2 K → ππ decay amplitudes. There have been worries that this divergence might show up in the Minkowski amplitudes at MK = Mπ with all the mesons at rest. Here we demonstrate, via an explicit calculation in leading-order Chiral Perturbation Theory, that the power divergence is absent at the above k...

We re-investigate the impact of isospin violation for extracting the s-wave ππ scattering phase shift difference δ 0 (M K) − δ 2 (M K) from K → ππ decays. Compared to our previous analysis in 2003, more precise experimental data and improved knowledge of low-energy constants are used. In addition, we employ a more robust data-driven method to obtain the phase shift difference δ 0

Mayer's second cluster integral for the pion gas is calculated in quantum mechanical approach. It is shown that nonresonant repulsive ππ-interactions as well as the finite width of resonances yield important but almost canceling contributions at typical chemical freeze-out temperatures of the hadron gas. The repulsive ππ-interactions to the second cluster integral is identified with Van der Waa...

We measure the CP -violating asymmetries in decays to the D → KK and D → ππ CP eigenstates using 540 fb of data collected with the Belle detector at or near the Υ(4S) resonance. Cabibbo-favored D → Kπ decays are used to correct for systematic detector effects. The results, A CP = (−0.43 ± 0.30 ± 0.11)% and A ππ CP = (+0.43± 0.52 ± 0.12)%, are consistent with no CP violation.

We have evaluated forward dispersion relations for scattering amplitudes that follow from direct fits to several sets of ππ scattering experiments, together with the precise K decay results, and high to energy data. We find that some of the most commonly used experimental sets, as well as some recent theoretical analyses based on Roy equations, do not satisfy these constraints by several standa...

We study a new K → ππ decay channel with gluons in intermediate state which is normally neglected within the factorization framework. Both short-distance and long-distance parts of the amplitude are calculated. The chiral Lagrangian approach is used for obtaining the long-distance contribution. The nonperturbative contribution gives an additional enhancement to K → ππ decay amplitude with ∆I = ...

We report on recent progress in studying two aspects of B physics, in which penguin amplitudes play an important role: 1. Bounds on penguin pollution in B(t) → ππ constraining the CKM parameters ρ and η, and a lower bound on B → ππ improving precision in sin 2α. 2. A suggestion for measuring the photon polarization in electroweak penguin decay, B → K1(1400)γ, providing a test of the Standard Mo...

We present the alternative way of derivation of the Wandzura-Wilczek relations between the kinematical twist-3 and twist-2 functions, parameterizing hadronic matrix element in two-photon processes γπ → γπ and γγ → ππ. The new equations, providing the independence of the physical cross-sections on the choice of the light-cone direction, are suggested and explored. The amplitude of γγ → ππ up to ...

K → ππ, KL-KS mass difference, KL → γγ and the Dalitz decays of KL are studied systematically by assuming that their amplitude can be described in terms of a sum of short distance and long distance contributions. Dominance of the short distance effect on the KL-KS mass difference will be checked by the Dalitz decays of KL in a way consistent with the K → ππ and KL → γγ decays.

We look at methods to determine the weak phases φ2 and φ3 from B → ππ and Kπ decays within the perturbative QCD approach. We obtain quite interesting bounds on φ2 and φ3 from experimental measurement in B-factory: 55 ≤ φ2 ≤ 100 and 51 ≤ φ3 ≤ 129. Specially we predict the possibility of large direct CP violation effect in B → ππ (23± 7%) decay. DPNU-02-28 hep-ph/0209002