Assuming the QCD multipole expansion is applicable to hadronic transitions of Υ(3S) into lower level bottomonia, we consider the possibility that Υ(3S) has a D−wave component. This assumption leads to a natural explanation of the ππ spectrum in Υ(3S) → Υ(1S) ππ. Consequences of this assumption on other hadronic and radiative transitions of Υ(3S) are also discussed in the same context. PACS numb...

In the previous work, analyzing the I=0 S-wave ππ-scattering phase-shift through a new method of Interfering Breit-Wigner amplitudes, we have shown possibility of existence of a light scalar, σ particle, by assuming a negative back-ground phaseshift, corresponding to “repulsive core” in ππ-interaction. In this work we investigate further, to what extent, σ-properties and size of core radius are...

The analysis of the poles of the ππ scattering amplitude is shown to favour a dynamical origin of the sigma meson: it is created by a strongly attractive ππ interaction in the J = 0I = 0 channel. In the limit Nc → ∞, the σ meson disappears, contrary to the case of conventional qq̄ states. Implications for the search of the scalar qq̄ and glueball states are discussed.

Strong final-state interactions create a pronounced cusp in η → ηππ decays. We adapt and generalize the non-relativistic effective field theory framework developed for the extraction of ππ scattering lengths from K → 3π decays to this case. The cusp effect is predicted to have an effect of more than 8% on the decay spectrum below the ππ threshold. PACS. 11.30.Rd Chiral symmetries – 13.25.Jx Dec...

A new study is reported of a lattice QCD calculation of the K → ππ decay amplitude with the Wilson quark action in the quenched approximation at β = 6.1. The amplitude is extracted from the K → ππ Green function, and a conversion to the continuum value is made employing a recent one-loop calculation of chiral perturbation theory. The result is consistent with the experimental value if extrapola...

In benzophenone, intersystem crossing occurs efficiently between the S1(nπ*) state and the T1 state of dominant nπ* character, leading to excited triplet states after photoexcitation. The transition mechanism between S1(nπ*) and T1 is still a matter of debate, despite several experimental studies. Quantum mechanical calculations have been performed in order to assess the relative efficiencies o...

The techniques of lattice gauge theory offer the possibility of accurate, non-perturbative calculation of the masses and matrix elements predicted by low-energy QCD. Of particular interest are the properties of the K-meson system and the lowenergy, weak matrix elements that are required to understand Kaon decays, especially those which enter the K → ππ amplitudes which violate CP symmetry. Pres...

B decays into ππK and KKK, where the ππ and KK pairs interact in isospin zero S-wave, are studied in the ππ effective mass range from threshold to 1.2 GeV. The interplay of strong and weak decay amplitudes is analyzed using an unitary ππ and KK coupled channel model. Final state interactions are described in terms of four scalar form factors constrained by unitarity and chiral perturbation theo...

We use a nonpertubative approach which combines coupled channel Lippmann Schwinger equations with meson-meson potentials provided by the lowest order chiral Lagrangian. By means of one parameter, a cut off in the momentum of the loop integrals, which results of the order of 1 GeV, we obtain singularities in the S-wave amplitudes corresponding to the σ, f0 and a0 resonances. The ππ → ππ , ππ → K...

In the framework of heavy baryon chiral perturbation theory, we give the chiral expansion for the πN → ππN threshold amplitudes D1 and D2 to quadratic order in the pion mass. The theoretical results agree within one standard deviation with the empirical values. We also derive a relation between the two threshold amplitudes of the reaction πN → ππN and the ππ S–wave scattering lengths, a0 and a0...