Cross-link relations between π and ρ -meson channels and the QCD vacuum

THE SEMILEPTONIC DECAYS D → π(ρ)eν AND B → π(ρ)eν FROM QCD SUM RULES

We investigate the semileptonic decays of B and D mesons into π and ρ mesons, respectively, by means of QCD sum rules. We find that for the vector formfactors involved the pole dominance hypothesis is valid to good accuracy with pole masses in the expected range. Pole dominance, however, does not apply to the axial formfactors which results in specific predictions for the predominant polarizati...

The decay ρ 0 → π 0 π 0 γ and the role of σ - meson

Vector meson dominance and the ρ meson

We discuss the properties of vector mesons, in particular the ρ 0 , in the context of the Hidden Local Symmetry (HLS) model. This provides a unified framework to study several aspects of the low energy QCD sector. Firstly, we show that in the HLS model the physical photon is massless, without requiring off field diagonalization. We then demonstrate the equivalence of HLS and the two existing re...

The QCD description of diffractive ρ meson electroproduction

We critically review the QCD predictions for the cross sections σL and σT for diffractive ρmeson electroproduction in longitudinally and transversely polarised states in the HERA energy region. We show that both perturbative and non-perturbative approaches which involve convolution with the ρ meson wave function predict values of σT which fall-off too quickly with increasing Q2, in comparison w...

Magnetic moment of the ρ-meson in QCD sum rules

The magnetic moment μ of the ρ-meson is calculated in the framework of QCD sum rules in external fields. Bare loop calculations (parton model) give: μpart = 2.0. The contribution of operators of dimension 6 reduces this value: μ = 1.5± 0.3. ∗e-mail:[email protected]