Polarizacijski podaci za protone iz JLaba i globalni unitarni i analitički model EM strukture nukleona

It is demonstrated that the new JLab proton polarization data, which are in a rather strong disagreement with the proton electric form factor data in the space-like region obtained by the Rosenbluth technique, are consistent with all known form factor properties, including also the QCD asymptotics. However, they require the existence of a zero value (i.e. a diffraction minimum) of the proton electric form factor around t=15 GeV2. That leads to a change of our understanding of the charge distribution inside the proton.Pokazujemo da novi polarizacijski podaci iz JLaba za protone, koji su u velikom neskladu s podacima za protonski električni faktor oblika u prostornom području izvedenim Rosenbluthovom metodom, su u skladu sa svim poznatim svojstvima faktora oblika, uključivši i QCD asimptotičke vrijednosti. Međutim, oni zahtijevaju nultu vrijednost (tj., difrakcijski minimum) protonskog električnog faktora oblika oko t=15 GeV2 . To mijenja naše poznavanje raspodjele naboja u protonu

Faktori oblika pseudoskalarnih mezona od vektorske struje stranih kvarkova

Similarly to the electromagnetic pseudoscalar-meson transition form factors, one can also define strange-quark vector current pseudoscalar-meson transition form factors, contributing only to the behaviour of the isoscalar parts of the former ones. Their explicit form is found by constructing unitary and analytical models of the strange pseudoscalar-meson transition form factors dependent only on ω and φ coupling constant ratios as free parameters. Numerical values of these ratios are then determined from the corresponding pseudoscalar-meson transition form factors by employing the ω-φ mixing and a special assumption on the coupling of the quark components of vector-meson wave functions to the flavour component of currents under consideration.Poput elektromagnetskih prijelaznih faktora oblika pseudoskalarnih mezona, mogu se definirati i prijelazni faktori oblika pseudoskalarnih mezona od vektorske struje stranih kvarkova, koji doprinose samo svojstvima izoskalarnih dijelova prvih. Njihova se eksplicitna formulacija nalazi razvijanjem unitarnih i analitičkih modela za strane prijelazne faktore oblika pseudoskalarnih mezona koji ovise samo o omjerima konstanti vezanja ω and φ mezona kao slobodnim parametrima. Iznosi tih omjera se određuju iz odnosnih prijelaznih faktora oblika pseudoskalarnih mezona upotrebom posebnog miješanja ω-φ i posebnom pretpostavkom o vezanju kvarkovskih komponenata valnih funkcija vektorskih mezona na okusnu komponentu studiranih struja

Manifestation of the JLab proton polarization data on the behaviour of strange nucleon form factors

Special eight-resonance unitary and analytic model of nucleon electromagnetic structure is used to analyze, first the classical proton form factor data obtained by the Rosenbluth technique and then also the contradicting JLab proton polarization data on the ratio $\mu_p G_{Ep}(Q^2)/G_{Mp}(Q^2)$ with the aim to investigate a manifestation of the latter on the strange nucleon form factors behaviour.Comment: Latex, 9 pages, 3 figures. Talk given at the PAVI06 International Workshop, 16-20 May, 2006, Milos, Greec

Study of Bs→ℓ+ℓ−γB_s\to\ell^+\ell^-\gamma decays in covariant quark model

We study the rare radiative leptonic decays $B_s\to\ell^+\ell^-\gamma$ ($\ell=e,\mu,\tau$) within the Standard Model, considering both the structure-dependent amplitude and bremsstrahlung. In the framework of the covariant confined quark model developed by us, we calculate the form factors characterizing the $B_s\to\gamma$ transition in the full kinematical region of the dilepton momentum squared and discuss their behavior. We provide the analytic formula for the differential decay distribution and give predictions for the branching fractions in both cases: with and without long-distance contributions. Finally, we compare our results with those obtained in other approaches.Comment: 22 pages, 8 figures, 6 tables, more references and material added, a version to appear on PR

Phenomenological insight into JLab proton polarization data puzzle by deuteron impulse approximation

The non-relativistic impulse approximation of deuteron electromagnetic form factors is used to investigate the space-like region behavior of the proton electric form factor in regard of the two contradictory experimental results extracted either from Rosenbluth separation method or from recoil proton JLab polarization data.Comment: Revtex, 6 pages, 7 figure

Polarization effects in e++e−→dˉ+de^+ +e^-\to \bar d+d and determination of time like deuteron form factors

Polarization effects in the reaction $e^++e^-\to \bar d+d$ have been investigated for the case of longitudinally polarized electron beam and arbitrary polarization of the produced deuteron, with the aim of a determination of the time-like complex deuteron electromagnetic form factors. General expressions of polarization observables are derived and numerical estimations have been carried out by means of various models of deuteron electromagnetic form factors, for kinematical conditions near threshold.Comment: 19 pages, 3 figure