7,248 research outputs found
Imperfect rationality, macroeconomic equilibrium and price rigidities
We introduce some elements of Prospect Theory into a general equilibrium model with monoolistic competition in the good market and real wage rigidities due to (right to manage or efficient) wage bargaining, or to efficiency wages. We show that, under these types of labor market frictions, an increase in workers’ loss aversion: (i) reduces the equilibrium wage and in this way increases potential output; (ii) induces workers to work and consume less and in this way decreases potential output. If the former effect is greater (smaller) than the latter one, loss aversion increases (decreases) potential output. We also show that, under all the types of labor market frictions we consider, if loss aversion reduces equilibrium output, it also enhances the plausibility of nominal price rigidities
Density-wave phases of dipolar fermions in a bilayer
We investigate the phase diagram of dipolar fermions with aligned dipole
moments in a two-dimensional (2D) bilayer. Using a version of the
Singwi-Tosi-Land-Sjolander scheme recently adapted to dipolar fermions in a
single layer [M. M. Parish and F. M. Marchetti, Phys. Rev. Lett. 108, 145304
(2012)], we determine the density-wave instabilities of the bilayer system
within linear response theory. We find that the bilayer geometry can stabilize
the collapse of the 2D dipolar Fermi gas with intralayer attraction to form a
new density wave phase that has an orientation perpendicular to the density
wave expected for strong intralayer repulsion. We thus obtain a quantum phase
transition between stripe phases that is driven by the interplay between strong
correlations and the architecture of the low dimensional system.Comment: 5 pages, 3 figure
Superfluidity, Sound Velocity and Quasi Condensation in the 2D BCS-BEC Crossover
We study finite-temperature properties of a two-dimensional superfluid made
of ultracold alkali-metal atoms in the BCS-BEC crossover. We investigate the
region below the critical temperature of the
Berezinskii-Kosterlitz-Thouless phase transition, where there is
quasi-condensation, by analyzing the effects of phase and amplitude
fluctuations of the order parameter. In particular, we calculate the superfluid
fraction, the sound velocity and the quasi-condensate fraction as a function of
the temperature and of the binding energy of fermionic pairs.Comment: 7 pages, 4 figures, improved version to be published in Phys. Rev.
Non-BCS superconductivity for underdoped cuprates by spin-vortex attraction
Within a gauge approach to the t-J model, we propose a new, non-BCS mechanism
of superconductivity for underdoped cuprates. The gluing force of the
superconducting mechanism is an attraction between spin vortices on two
different N\'eel sublattices, centered around the empty sites described in
terms of fermionic holons. The spin fluctuations are described by bosonic
spinons with a gap generated by the spin vortices. Due to the no-double
occupation constraint, there is a gauge attraction between holon and spinon
binding them into a physical hole. Through gauge interaction the spin vortex
attraction induces the formation of spin-singlet (RVB) spin pairs with a
owering of the spinon gap. Lowering the temperature the approach exhibits two
crossover temperatures: at the higher crossover a finite density of incoherent
holon pairs are formed leading to a reduction of the hole spectral weight, at
the lower crossover also a finite density of incoherent spinon RVB pairs are
formed, giving rise to a gas of incoherent preformed hole pairs, and magnetic
vortices appear in the plasma phase. Finally, at a even lower temperature the
hole pairs become coherent, the magnetic vortices become dilute and
superconductivity appears. The superconducting mechanism is not of BCS-type
since it involves a gain in kinetic energy (for spinons) coming from the spin
interactions.Comment: 4 pages, 3 figures, accepted by the proceedings of SNS2010 conferenc
Phase Equilibrium of Binary Mixtures in Mixed Dimensions
We study the stability of a Bose-Fermi system loaded into an array of coupled
one-dimensional (1D) "tubes", where bosons and fermions experience different
dimensions: Bosons are heavy and strongly localized in the 1D tubes, whereas
fermions are light and can hop between the tubes. Using the 174Yb-6Li system as
a reference, we obtain the equilibrium phase diagram. We find that, for both
attractive and repulsive interspecies interaction, the exact treatment of 1D
bosons via the Bethe ansatz implies that the transitions between pure fermion
and any phase with a finite density of bosons can only be first order and never
continuous, resulting in phase separation in density space. In contrast, the
order of the transition between the pure boson and the mixed phase can either
be second or first order depending on whether fermions are allowed to hop
between the tubes or they also are strictly confined in 1D. We discuss the
implications of our findings for current experiments on 174Yb-6Li mixtures as
well as Fermi-Fermi mixtures of light and heavy atoms in a mixed dimensional
optical lattice system.Comment: 12 pages, 6 figure
Dipolar fermions in a multilayer geometry
We investigate the behavior of identical dipolar fermions with aligned dipole
moments in two-dimensional multilayers at zero temperature. We consider density
instabilities that are driven by the attractive part of the dipolar interaction
and, for the case of bilayers, we elucidate the properties of the stripe phase
recently predicted to exist in this interaction regime. When the number of
layers is increased, we find that this "attractive" stripe phase exists for an
increasingly larger range of dipole angles, and if the interlayer distance is
sufficiently small, the stripe phase eventually spans the full range of angles,
including the situation where the dipole moments are aligned perpendicular to
the planes. In the limit of an infinite number of layers, we derive an analytic
expression for the interlayer effects in the density-density response function
and, using this result, we find that the stripe phase is replaced by a collapse
of the dipolar system.Comment: 9 pages, 8 figure
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