arXiv subjects

Petr Zavada

Publications and source records attributed to Petr Zavada.

22 records · Page 2Linked to original sources

arXiv2002

Spin structure functions and intrinsic motion of the constituents

The spin structure functions of the system of quasifree fermions on mass shell are studied in a consistently covariant approach. Comparison with the basic formulas following from the quark-parton model reveals the importance of the fermion motion inside the target for the correct evaluation of the spin structure functions. In particular it is shown, that regarding the moment $Γ_{1}$, both the approaches are equivalent for the static fermions, but differ by the factor 1/3 in the limit of massles fermions ($% m \ll p_0$, in target rest frame). Some other sum rules are discussed as well.

hep-ph↗

arXiv2001

Proton spin structure and quark-parton model

The alternative to the standard formulation of the quark-parton model is proposed. Our relativistically covariant approach is based on the solution of the master equations relating the structure and distribution functions, which consistently takes into account the intrinsic quark motion. It is suggested, that the intrinsic quark motion can substantially reduce the structure function $g_1$. Simultaneously it is suggested, that the combined analysis of the polarized and unpolarized data can give an information about the effective masses and intrinsic motion of the quarks inside the nucleon.

hep-ph↗

arXiv1998

A model of anomalous production of strange baryons in nuclear collisions

We propose a simple model of production of strange baryons and antibaryons in nuclear collisions at the CERN SPS. The model takes into account both the increase of strangeness production in collisions of lighter ions and a possibility of the formation of anomalous, strangeness rich matter in central PbPb interactions. It is shown that ratios like $<Ω>:<Ξ>:<Λ>$ depend strongly on the presence of anomalous matter and can be used to determine its phenomenological parameters. In the model we assume that particle composition of final state hadrons is essentially given by a rapid recombination of quarks and antiquarks formed in tube-on-tube interactions of incoming nucleons.

hep-ph↗

arXiv1996

Nucleon number dependence of longitudinal radii in ion-ion collisions as a signature of the onset of collective expansion

In an attempt to disentangle the effects of nuclear geometry from those of nuclear geometry we study dependence of longitudinal radius on nucleon numbers of colliding nuclei within a simple model of multiple nucleon- nucleon collisions.We discuss two approaches to resulting simple formula.In the former the data up to S-Au can be described by nuclear geometry at the price of two parameters,but R_L for Pb-Pb is significantly larger than geometry can accomodate, indicating an onset of a new dynamics. In the latter even collisions induced by lighter ions give evidence of some collective behaviour and the increase of R_L for Pb-Pb indicates again the onset of a new dynamics.

hep-ph↗