Motivated by the observation that there may exist hadronic excitations even in the quark-gluon plasma (QGP) phase, we investigate how the properties of quarks, especially within the quasi-particle picture, are affected by the coupling with bosonic excitations at finite temperature (T ), employing Yukawa models with a massive scalar (pseudoscalar) and vector (axial-vector) boson of mass m. The q...

The cross sections for the production of Bs and B ∗ s mesons through the fragmentation process in p̄p collisions were calculated. The input parameters were determined from the measured Bs and B ∗ s production rates in e e annihilation. The transverse momentum distributions dσ/dpT are given for √ s = 1.8 TeV, the Fermilab Tevatron energy. At LEP the DELPHI Collaboration has measured the probabili...

We calculate the high energy behavior of quark-antiquark exchange in γ * γ * elastic scattering by summing, to all orders, the leading double logarithmic contributions of the QCD ladder diagrams. Motivation comes from the LEP data for σ γ * γ * tot which indicate the need for secondary reggeon exchange. We show that, for large photon virtualities, this exchange is calculable in pQCD. This appli...

We point out that the fragmentation of a strange quark into nucleons versus antinucleons is not necessarily identical Dp=s(z;Q 2) 6= Dp=s(z;Q 2), even though the perturbative contributions from gluon splitting and evolution are p $ p symmetric. The observation of such asymmetries in the hadronization of strange and other heavy quarks can provide insight into the nonperturbative mechanisms under...