Related papers: Heavy Quark Effects in the Virtual Photon Structur…
It is shown that recent small-x measurements of the photon structure function F_2^{\gamma}(x,Q^2) by the LEP-OPAL collaboration are consistent with parameter-free QCD predictions at all presently accessible values of Q^2.
We study soft-gluon radiation for heavy quark production in charged-current Deep Inelastic Scattering processes. We resum large-x contributions to the MSbar coefficient function to next-to-leading logarithmic accuracy and present results…
In this work, we look for possible new physics effects on the electromagnetic charge and anapole form factors, $f_Q(q^2)$ and $f_A(q^2)$, for a massless Dirac neutrino, when these quantities are calculated in the context of an effective…
The present status of the measurements of hadronic structure functions of the photon, investigated in deep inelastic electron-photon scattering at LEP, is presented. This article covers the hadronic structure function F_2^gamma of…
The $\pi^0 \gamma\gamma$ vertex for virtual photons of squared masses $q_1^2$ and $q_2^2$ plays a vital r\^ole in several physical processes; for example for $q_1^2<0$, $q_2^2<0$, in the two-photon physics reaction $e^+ e^-\to e^+ e^-…
Effects associated with hyperfine mass splitting between pseudo\-scalar and vector mesons may induce surprisingly large $1/{m}_{Q}^{2}$ corrections in the heavy quark expansion. We demonstrate this in a relativistic quark model by…
The cross section for exclusive heavy quark and heavy antiquark pair ($Q \bar Q$) production in peripheral ultrarelativistic heavy ion collisions is calculated for the LHC energy $\sqrt{s_{NN}}$ = 5.5 TeV. Here we consider only processes…
We consider models that generate hierarchies via the separation of fermion wavefunctions in higher-dimensional spaces. We calculate the effects of gauge interactions between fermions and show that these are important and could help to…
Multiple scattering, induced radiative energy loss and modified fragmentation functions of a heavy quark in nuclear matter are studied within the framework of generalized factorization in perturbative QCD. Modified heavy quark fragmentation…
We present a preliminary analysis of the heavy-heavy spectrum and heavy-light decay constants in full QCD, using a tadpole-improved SW quark action and an RG-improved gauge action on a 16^3 x 32 lattice with four sea quark masses…
The spin-averaged binding energy and the hyperfine mass splitting of heavy-light mesons are investigated within the constituent quark model as a function of the inverse heavy-quark mass. It is shown that the so-called heavy-quark kinetic…
We formulate and analyse a saturation model for the total gamma gamma and gamma* gamma* cross-sections and for the real photon structure function F_2^gamma(x,Q^2). The model is based on a picture in which the gamma* gamma* total…
We compute the full three-loop coefficient functions for the structure functions F_2 and F_L in massless perturbative QCD. The results for F_L complete the next-to-next-to-leading order description of unpolarized electromagnetic…
Methods are presented allowing a realistic, experiment-based simulation of low-mass quark pairs coupling to a virtual photon. Differential cross-section reweighting factors allow to reproduce the resonant structure observed near quark pair…
The heavy-quark spectral function in a hot plasma is reconstructed from the corresponding euclidean propagator. The latter is evaluated through a path-integral simulation. A weak-coupling calculation is also performed, allowing to interpret…
The framework of the expansion by subgraphs is used to compute asymptotic expansions for the vector and the tensor currents in the limit of large quark masses. We use the results to obtain an estimate for the influence of heavy quarks on…
We study the nuclear medium effects in the weak structure functions $F_2(x,Q^2)$ and $F_3(x,Q^2)$ in the deep inelastic neutrino/antineutrino reactions in nuclei. We use a theoretical model for the nuclear spectral functions which…
Motivated by experimental data at large momentum transfer we update the analysis of the two-photon exchange effect in the electron-nucleon scattering using the effective field theory formalism. Our approach is suitable for describing the…
At HERA heavy quarks may contribute up to 30% of the structure function $F_2$. The potential of including heavy-quark data in the ZEUS PDF fits is explored, using $D^*$ double differential cross-sections as well as the inclusive quantities…
In the framework based on the quasipotential method and relativistic quark model a new covariant expression for the heavy quark fragmentation amplitude to fragment into the pseudoscalar and vector S-wave heavy mesons is obtained. It…