179 research outputs found
Coupled Ferromagnetic and Nematic Ordering of Fermions in an Optical Flux Lattice
Ultracold atoms in Raman-dressed optical lattices allow for effective
momentum-dependent interactions among single-species fermions originating from
short-range s-wave interactions. These dressed-state interactions combined with
very flat bands encountered in the recently introduced optical flux lattices
push the Stoner instability towards weaker repulsive interactions, making it
accessible with current experiments. As a consequence of the coupling between
spin and orbital degrees of freedom, the magnetic phase features Ising nematic
order.Comment: 5 pages, 4 figures (published version
Two-body recombination in a quantum mechanical lattice gas: Entropy generation and probing of short-range magnetic correlations
We study entropy generation in a one-dimensional (1D) model of bosons in an
optical lattice experiencing two-particle losses. Such heating is a major
impediment to observing exotic low temperature states, and "simulating"
condensed matter systems. Developing intuition through numerical simulations,
we present a simple empirical model for the entropy produced in this 1D
setting. We also explore the time evolution of one and two particle correlation
functions, showing that they are robust against two-particle loss. Because of
this robustness, induced two-body losses can be used as a probe of short range
magnetic correlations.Comment: 6 pages, 3 figures - v4, published versio
Stirring trapped atoms into fractional quantum Hall puddles
We theoretically explore the generation of few-body analogs of fractional
quantum Hall states. We consider an array of identical few-atom clusters
(n=2,3,4), each cluster trapped at the node of an optical lattice. By
temporally varying the amplitude and phase of the trapping lasers, one can
introduce a rotating deformation at each site. We analyze protocols for
coherently transferring ground state clusters into highly correlated states,
producing theoretical fidelities in excess of 99%.Comment: 4 pages, 3 figures (13 subfigures) -- v2: published versio
High-polarization limit of the quasi-two-dimensional Fermi gas
We demonstrate that the theoretical description of current experiments of
quasi-2D Fermi gases requires going beyond usual 2D theories. We provide such a
theory for the highly spin-imbalanced quasi-2D Fermi gas. For typical
experimental conditions, we find that the location of the recently predicted
polaron-molecule transition is shifted to lower values of the vacuum binding
energy due to the interplay between transverse confinement and many-body
physics. The energy of the attractive polaron is calculated in the 2D-3D
crossover and displays a series of cusps before converging towards the 3D
limit. The repulsive polaron is shown to be accurately described by a 2D theory
with a single interaction parameter.Comment: 7 pages, 6 figures, published versio
Theory of the Normal/Superfluid interface in population imbalanced Fermi gases
We present a series of theoretical studies of the boundary between a
superfluid and normal region in a partially polarized gas of strongly
interacting fermions. We present mean-field estimates of the surface energy in
this boundary as a function of temperature and scattering length. We discuss
the structure of the domain wall, and use a previously introduced
phenomonological model to study its influence on experimental observables.
Our microscopic mean-field calculations are not consistent with the magnitude
of the surface tension found from our phenomonological modelling of data from
the Rice experiments. We conclude that one must search for novel mechanisms to
explain the experiments.Comment: 15 pages, 9 figures (13 subfigures) -- v2: minor change
Electroweak radiative corrections to W-boson production at hadron colliders
The complete set of electroweak O(alpha) corrections to the Drell--Yan-like
production of W bosons is calculated and compared to an approximation provided
by the leading term of an expansion about the W-resonance pole. All relevant
formulae are listed explicitly, and particular attention is paid to issues of
gauge invariance and the instability of the W bosons. A detailed discussion of
numerical results underlines the phenomenological importance of the electroweak
corrections to W-boson production at the Tevatron and at the LHC. While the
pole expansion yields a good description of resonance observables, it is not
sufficient for the high-energy tail of transverse-momentum distributions,
relevant for new-physics searches.Comment: 29 pages, latex, 17 postscript files, revised version that is to
appear in Phys.Rev.D, some explanations added and results extended by a
discussion of the QED factorization scale dependenc
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