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Using a QCD relativistic potential model, previously applied to the calculation of the heavy meson leptonic constants, we evaluate the form factors governing the exclusive decays $B\to\rho\ell\nu$, $B\to K^*\gamma$ and $B\to K^*\ell^+\ell^-$. In our approach the heavy meson is described as a $Q\overline q$ bound state, whose wave function is solution of the relativistic Salpeter equation, with an instantaneous potential displaying Coulombic behaviour at small distances and linear behaviour at large distances. The light vector meson is described by using a vector current interpolating field, according to the Vector Meson Dominance assumption. A Pauli-Villars regularized propagator is assumed for the quarks not constituting the heavy meson. Our procedure allows to avoid the description of the light meson in terms of wave function and constituent quarks, and consequently the problem of boosting the light meson wave function. Assuming as an input the experimental results on $B\to K^*\gamma$, we evaluate all the form factors describing the $B\to \rho, K^*$ semileptonic and rare transitions. The overall comparison with the data, whenever available, is satisfactory. [ABSTRACT FROM AUTHOR]

Long-distance, nonperturbative effects in the parity-violating pion-nucleon coupling constant E are calculated. Our result is E = (2.1-5.5) .10 in agreement with the present experimental data [ABSTRACT FROM AUTHOR]

We perform a systematic analysis of different processes with high energy polarized proton beams: jets, direct photon, lepton pairs (Drell-Yan) and WZ production. Different sets of polarized partonic densities are used that fit EMC and SLAC polarized deep inelastic scattering data with variable amount of quark and gluon components of the proton spin. The case of the future Relativistic Heavy Ion Collider (RHIC) used as a polarized collider at a maximum energy of $$\sqrt s = 500$$ GeV is analyzed in detail. [ABSTRACT FROM AUTHOR]

We propose a model of polarized partonic densities based on Regge behaviour, quark counting rules, U(1) Goldberger-Treiman relation and positivity constraints. The resulting polarized proton structure function is found to be in agreement with EMC and SLAC data. From this input we compute double helicity asymmetries for 1 and 2 jet inclusive production in polarized proton proton scattering at high energies. We obtain asymmetries of 10-20% at energies $$\sqrt s = 50 - 500$$ GeV. [ABSTRACT FROM AUTHOR]

We estimate the rates of B decays into neutral charmed final states $$B^0 \to \overline {D^{ * 0} } \gamma ,B^0 \to \overline {D^{ * 0} } \pi ^0 ,B^0 \to \overline {D^0 } \pi ^0 ,B^0 \to \overline {D^0 } \omega $$ , by considering factorizable, vector meson dominance and long distance contributions. We also discuss the role of these decay modes as a source of background events in the search for exclusive b→sγ transitions in very high energy experiments, e.g. at LEP. [ABSTRACT FROM AUTHOR]

We estimate long distance corrections to radiative B → Kγ and to non leptonic B→ Kπ, B→ Kπ, B→ Kσ, B→ Kσ, B→ KΦ and B→ KΦ decays generated by the ( $$\overline b$$ c) ( $$\overline c$$ s) part of the non leptonic weak Hamiltonian. While vanishing in the vacuum saturation approximation, these corrections are finite if one includes single particle charmed states between the currents in the Hamiltonian. We find small effects in radiative decays, but significant contributions to several non leptonic processes. [ABSTRACT FROM AUTHOR]

Weapply WKB techniques to a Schrödinger equation modified for relativistic kinematics. We show that a potential consisting of linear and logarithmic terms accounts for different aspects of quarkonium phenomenology. Using an Extended Vector Meson Dominance model we calculate R e and we derive the Quark Parton Model result. [ABSTRACT FROM AUTHOR]

Using parity violating nucleon wave function effects we make predictions for spin asymmetries in pp and $$\bar p$$ p scattering at moderate and high energies [ABSTRACT FROM AUTHOR]

We calculate the ratio R in the framework of Anisotropic Chromo-Dynamics (ACD), a recently proposed approach to strong interactions, and we show that asymptotically the Quark Parton Model value is recovered. Scaling violations due to the quark-masses and to the structure of the $$q\bar q$$ -potential are also calculated. [ABSTRACT FROM AUTHOR]

Deep inelastic scattering on a photon target has been calculated in the framework of the Massive Quark Model (MQM). Precise predictions are given for the longitudinal and transverse structure function, and a comparison with the calculation of Quark Parton Model and of perturbative QCD is carried out. [ABSTRACT FROM AUTHOR]

Heavy-quark ( m →∞) flavour symmetry can be used together with the light-quark SU(3) flavour symmetry to relate the semi-leptonic decays B → ρℓ⥉ and D → Kℓν. We use recent data on the semi-leptonic D decays to make predictions on the B→ϱ transition. We also compare these predictions with other theoretical approaches and we show that, in order to discriminate among the different models, a measurement of the ϱ polarization would be useful. Heavyflavour symmetry can also be used to relate the decay processes D → Kℓν and B→Kγ, in the limit m →∞. We compare these predictions with the CLEO II data and we argue that a satisfactory agreement is found only if a consistent treatment of the O(1/ m ) corrections is performed. [ABSTRACT FROM AUTHOR]

Copyright of Il Nuovo Cimento: A is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Il Nuovo Cimento: A is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Il Nuovo Cimento: A is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Il Nuovo Cimento: A is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)