15,499 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
Degenerate quantum gases of strontium
Degenerate quantum gases of alkaline-earth-like elements open new
opportunities in research areas ranging from molecular physics to the study of
strongly correlated systems. These experiments exploit the rich electronic
structure of these elements, which is markedly different from the one of other
species for which quantum degeneracy has been attained. Specifically,
alkaline-earth-like atoms, such as strontium, feature metastable triplet
states, narrow intercombination lines, and a non-magnetic, closed-shell ground
state. This review covers the creation of quantum degenerate gases of strontium
and the first experiments performed with this new system. It focuses on
laser-cooling and evaporation schemes, which enable the creation of
Bose-Einstein condensates and degenerate Fermi gases of all strontium isotopes,
and shows how they are used for the investigation of optical Feshbach
resonances, the study of degenerate gases loaded into an optical lattice, as
well as the coherent creation of Sr_2 molecules.Comment: Review paper, 43 pages, 24 figures, 249 reference
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
Changing quantum reference frames
We consider the process of changing reference frames in the case where the
reference frames are quantum systems. We find that, as part of this process,
decoherence is necessarily induced on any quantum system described relative to
these frames. We explore this process with examples involving reference frames
for phase and orientation. Quantifying the effect of changing quantum reference
frames serves as a first step in developing a relativity principle for theories
in which all objects including reference frames are necessarily quantum.Comment: 21 pages, 6 figures, comments welcome; v2 added some references; v3
published versio
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