Coherent ω photoproduction from nuclei and ω properties in nuclear matter. Abstract. The coherent ω-meson photoproduction from nuclei is proposed as a phenomenological method to evaluate the momentum dependence of ω-meson mass shift and width in nuclear matter. We analyze available data on un-separated coherent and incoherent ω-meson photoproduction from nuclei and extract the imaginary part of...

We discuss two descriptions of the nucleon’s strange vector form factors in the framework of vector meson dominance. The first, an updated and extended version of Jaffe’s dispersion analysis, approximates the spectral functions of the form factors as a sum of vector meson poles, whereas the second combines vector meson dominance in the ω and φ meson sector with an intrinsic strangeness distribu...

The radiative meson decays V → Pγ and P → γγ are analyzed using the quark triangle diagram. Experimental data yield well determined estimates of the universal quark-antiquark-meson couplings gV qq̄′ and gPqq̄′ for the light meson sector. Also predictions for the ratios of neutral to charged heavy meson decay coupling constants are given and await experimental confirmation. 13.25.-k, 12.40.Vv, 13....

A complete set of formulae in terms of the moment–operator expansion is presented for the two-meson, two-photon and fermion-antifermion states that can be used in the analysis of scalar (S) and pseudoscalar (P ) meson production in pp̄ and γγ collisions: pp̄ → SS,PP, SP and γγ → SS,PP, SP . Method of a generalization of the formulae for amplitudes of multi-meson production in the two-stage proces...

Diquarks are found to have the right degrees of freedom to describe the tetraquark poles in hiddencharm to open-charm meson-meson amplitudes. Compact tetraquarks result as intermediate states in non-planar diagrams of the 1/N expansion and the corresponding resonances are narrower than what estimated before. The proximity of tetraquarks to meson-thresholds has an apparent role in this analysis ...

In this paper we propose a knot model of the π mesons. In this knot model we give the formation of the π meson by strong interaction and the decay of the π meson to the moun μ and the moun neutrino νμ by weak interaction. We give a mass machanism for the generation of the masses of the π 0 meson, π meson, the moun μ and the moun neutrino νμ. PACS numbers: 12.90.+b, 12.40.Yx, 12.10.Dm.

The fermion and meson sectors of the quark-level SU(2) linear sigma model are dynamically generated from a meson-quark Lagrangian, with the quark (q) and meson (σ, π) fields all treated as elementary, having neither bare masses nor expectation values. In the chiral limit, the masses are predicted to be mq = fπg, mπ = 0, mσ = 2mq, and we also find that the quark-meson coupling is g = 2π/ √ Nc, t...

Discussion of the η → π 0 γγ decay within a chiral unitary approach We improve the calculations of the η → π 0 γγ decay within the context of meson chiral lagrangians. We use a chiral unitary approach for the meson-meson interaction, thus generating the a0(980) resonance and fixing the longstanding sign ambiguity on its contribution. This also allows us to calculate the loops with one vector me...

Two-meson-exchange nucleon-nucleon potentials are derived where either one or both nucleons contains a pair vertex. Physically, the meson-pair vertices are meant to describe in an effective way (part of) the effects of heavy-meson exchange and meson-nucleon resonances. From the point of view of " duality, " these two kinds of contribution are roughly equivalent. The various possibilities for me...

We improve the calculations of the h→p0gg decay within the context of meson chiral Lagrangians. We use a chiral unitary approach for the meson-meson interaction, thus generating the a0(980) resonance and fixing the long standing sign ambiguity on its contribution. This also allows us to calculate the loops with one vector meson exchange, thus removing a former source of uncertainty. In addition...