A. Bramon

A vector meson dominance approach to scale invariance

Abstract A model of scale invariance for both deep inelastic scattering and e + e − annihilation incorporating an infinite number of vector mesons is proposed. Structure functions are calculated explicitly in good agreement with experiments. Precocious scaling arises naturally in the model.

Quark model predictions for radiative decays of mesons

Abstract From simple quark model arguments and assuming a quadratic η − η ′ mixing we predict the radiative decays of the vector and pseudoscalar mesons, in good agreement with experiments. Our results strongly favour the new determination of the η → γγ partial width.

RADIATIVE DECAYS OF MESONS AND AN EXTENDED VECTOR MESON DOMINANCE MODEL.

SummaryA model describing the radiative P→γγ, V→Pγ, P→PPγ and the strong V→PPP decays is proposed. The amplitudes for processes with a three-particle final state are approximated by finite dispersion relations and the coupling constants are related by the quark model. Predictions derived from usual VMD are only in qualitative agreement with experiments. Better agreement is achieved by extending VMD with the inclusion of further vector mesons.RiassuntoSi propone un modello per descrivere i decadimenti radiativi P→γγ, V→Pγ, P→PPγ ed i decadimenti forti V→PPP. Le ampiezze per processi con tre particelle nello stato finale sono descritte per mezzo di relazioni di dispersione finite e le costanti di accoppiamento sono fra loro collegate tramite il modello a quark. Le predizioni derivate dall’usuale predominio del mesone vettoriale sono soltanto in accordo qualitativo con gli esperimenti. Un migliore accordo si ricava estendendo il predominio del mesone vettoriale con l’inclusione di ulteriori mesoni vettoriali.

Nonet structure of the J PC =3 −− mesons

SummaryThe meson resonances g(1660),ϕN(1650),ϕN(1830) and KN(1760) are tentatively grouped in an «ideal»SU3 nonet havingJPC=3−−. A discussion of their masses and their decay modes is presented showing general agreement with the available experimental data. Our results are also discussed in the light of finite-energy, sum rules for the reactions πK → ωK and πK → ϕK.RiassuntoLe risonanze mesoniche g(1650),ϕN(1650),ϕN(1830) e KN(1760) sono classificate in un nonetto «ideale» diSU3 aventeJPC=3−−. Si presenta una discussione delle loro masse e dei relativi modi di decadimento che risultano essere in buon accordo con i dati sperimentali a disposizione. I nostri risultati sono anche discussi alla luce di regole di somma ad energia finita applicate alle reazioni πK → ωK e πK → ϕK.РезюмеМезонные резонансы g(1660),ϕN(1650),ϕN(1830) и KN(1760), в порядке эксперимента, группируются в «идеальный»SU3 нонет, имеющийJPC=3−−. Проводится обсуждение их масс и мод распада, которые обнаруживают общее согласие с имеющимися экспериментальными данными. Наши результаты рассматриваются также в свете правил сумм при конечной энергии для реакций πK → ωK и πK → ϕK.