12,273 research outputs found
Perturbative corrections to the Gutzwiller mean-field solution of the Mott-Hubbard model
We study the Mott-insulator transition of bosonic atoms in optical lattices.
Using perturbation theory, we analyze the deviations from the mean-field
Gutzwiller ansatz, which become appreciable for intermediate values of the
ratio between hopping amplitude and interaction energy. We discuss corrections
to number fluctuations, order parameter, and compressibility. In particular, we
improve the description of the short-range correlations in the one-particle
density matrix. These corrections are important for experimentally observed
expansion patterns, both for bulk lattices and in a confining trap potential.Comment: 10 pages, 10 figue
Next-to-leading order QCD corrections to hadron+jet production in pp collisions at RHIC
We compute the next-to-leading order QCD corrections to the spin-independent
and spin-dependent cross-sections for the production of a single-hadron
accompanied by an opposite jet in hadronic collisions.
This process is being studied experimentally at RHIC, providing a new tool to
unveil the polarized gluon distribution Delta g. We perform a detailed analysis
of the phenomenological impact of the observable at NLO accuracy and show that
the preliminary data by the STAR collaboration confirms the idea of a small
gluon polarization in the 0.05<x<0.3 range.Comment: 16 pages, 11 Figures included. Minor typos correcte
On the nature of Thermal Diffusion in binary Lennard-Jones liquids
The aim of this study is to understand deeper the thermal diffusion transport
process (Ludwig-Soret effect) at the microscopic level. For that purpose, the
recently developed reverse nonequilibrium molecular dynamics method was used to
calculate Soret coefficients of various systems in a systematic fashion. We
studied binary Lennard-Jones (LJ) fluids near the triple point (of one of the
components) in which we separately changed the ratio of one of the LJ
parameters mass, atomic diameter and interaction strength while keeping all
other parameters fixed and identical. We observed that the magnitude of the
Soret coefficient depends on all three ratios. Concerning its sign we found
that heavier species, smaller species and species with higher interaction
strengths tend to accumulate in the cold region whereas the other ones
(lighter, bigger or weaker bound) migrate to the hot region of our simulation
cell. Additionally, the superposition of the influence of the various
parameters was investigated as well as more realistic mixtures. We found that
in the experimentally relevant parameter range the contributions are nearly
additive and that the mass ratio often is the dominating factor.Comment: 27 pages, 9 figures, submitted to J. Chem. Phy
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