9 research outputs found
An Approach towards a Constituent Quark Model on the Light Cone
We use the vacuum expectation value of a Wegner-Wilson loop representing a
fast moving quark-antiquark pair to derive the light cone Hamiltonian for a
meson. We solve the corresponding Schr\"odinger equation for various
trial wave functions. The result shows how confinement determines the meson
mass and wave function for valence quarks on the light cone. We also
parametrize the effect of the spin-dependent splitting for a light meson and
charmonium. The correct chiral-symmetry breaking pattern for the pion mass is
obtained due to the self-energy of the quark.Comment: 17 pages and 5 figure
Gluon Shadowing in DIS off Nuclei
Within a light-cone quantum-chromodynamics dipole formalism based on the
Green function technique, we study nuclear shadowing in deep-inelastic
scattering at small Bjorken xB < 0.01. Such a formalism incorporates naturally
color transparency and coherence length effects. Calculations of the nuclear
shadowing for the \bar{q}q Fock component of the photon are based on an exact
numerical solution of the evolution equation for the Green function, using a
realistic form of the dipole cross section and nuclear density function. Such
an exact numerical solution is unavoidable for xB > 0.0001, when a variation of
the transverse size of the \bar{q}q Fock component must be taken into account.
The eikonal approximation, used so far in most other models, can be applied
only at high energies, when xB < 0.0001 and the transverse size of the \bar{q}q
Fock component is "frozen" during propagation through the nuclear matter. At xB
< 0.01 we find quite a large contribution of gluon suppression to nuclear
shadowing, as a shadowing correction for the higher Fock states containing
gluons. Numerical results for nuclear shadowing are compared with the available
data from the E665 and NMC collaborations. Nuclear shadowing is also predicted
at very small xB corresponding to LHC kinematical range. Finally the model
predictions are compared and discussed with the results obtained from other
models.Comment: 29 pages including 7 figures; Fig.7 modified, some references and
corresponding discussion adde
Phase equilibria in the cristobalite, tridymite and pyroxene primary phase fields in the MgO-"FeO"-SiO2 system in equilibrium with metallic iron
Experimental studies have been carried out to determine the phase equilibria for the ternary MgO-"FeO"-SiO2, in equilibrium with metallic iron. Liquiclus isotherms have been determined in the temperature range from 1 578 to 1 898K in the silica and pyroxene primary phase fields using high temperature equilibration, modified quenching and electron probe X-ray microanalysis (EPMA) techniques