The hypothesis of σ meson pole dominance in the |∆I| = 1 2 K → ππ amplitudes is tested qualitatively by using the KL-KS mass difference. Dominance of σ-meson pole contribution in the amplitudes for the KS → ππ decays was first proposed as the origin of the well-known |∆I| = 1 2 rule in these decays [1], and recently revived in connection with the direct CP violation in the K → ππ decays [2]. If...

A major problem in the determination of the the CP angle α, that should be measured through modes of the type B d , ¯ B d → ππ, · · · , is the uncertainty coming from Penguin diagrams. We consider the different ground state modes ππ, πρ, ρρ, and, assuming the FSI phases to be negligible, we investigate the amount of uncertainty coming from Penguins that can be parametrized by a dilution factor ...

To make the ππ state with non-zero relative momentum as the leading exponential, we impose anti-periodic boundary condition on the pion, which is implemented by imposing G-parity or H-parity on the quark fields at the boundary. With this, we calculate the I = 2 ππ phase shift from lattice simulation by using Lüscher's formula.

Thermal Bergman cyclization of Pt(II) dialkynylporphyrins reveals a marked reduction in the cyclization temperature relative to the free base and Zn(II) derivatives. In contrast, photogenerated (3)ππ* population produces no detectable Bergman photocyclization, suggesting that the photoreactivities of the related free base and Zn(II) derivatives occurs via the (1)ππ* state.

Four of the six parameters defining the two-loop ππ scattering amplitude have been determined using Roy dispersion relations. Combining this information with the Standard χPT expressions, we obtain the threshold parameters, low-energy phases and the O(p) constants l 1, l r 2. The result l r 2(Mρ) = (1.6 ± 0.4 ± 0.9) × 10 −3 (l̄2 = 4.17 ± 0.19 ± 0.43) reproduces the correct D-waves but it is inco...

The scalar-isoscalar, scalar-isotensor and vector-isovector ππ amplitudes have been fitted simultaneously to experimental data and to to Roy’s equations. Resulting ππ phase shifts up to 1600 MeV and near threshold observables have been analyzed. Only the amplitudes fitted to the ”down-flat” set of phase shifts in scalarisoscalar wave fulfill crossing symmetry conditions and can be regarded as p...

We review our recent work on unitarization and chiral perturbation theory both in the ππ and the πN sectors. We pay particular attention to the Bethe-Salpeter and Inverse Amplitude unitarization methods and their recent applications to ππ and πN scattering.

Paramagnetic metals are frequently used to regulate fluorescence emissions in chemical and biological probes. Accurate quantum calculations offer the first regulation theory that quenching is through the competitive nonradiative decay of the mixed fluorophore/metal (3)ππ*/dd state isoenergetic to the fluorophore-localized (1)ππ* state.

The leading twist parametrization of dipion mass distribution in hard exclusive reactions is proposed. Its parameters are related to quark distributions (usual and skewed) in the pion and to distributions amplitudes of mesons (π, ρ, etc.). We show that measurements of the shape of dipion mass distribution in hard exclusie reactions can give important information about partonic structure of the ...

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.