52,582 research outputs found
Quantum criticality out of equilibrium in the pseudogap Kondo model
We theoretically investigate the non-equilibrium quantum phase transition in
a generic setup: the pseudogap Kondo model where a quantum dot couples to
two-left (L) and right (R)-voltage-biased fermionic leads with power-law
density of states (DOS) with respect to their Fermi levels {\mu}_L/R,
{\rho}_c,L(R) ({\omega}) \propto |{\omega} - {\mu}_L(R) |r, and 0 < r < 1. In
equilibrium (zero bias voltage) and for 0 < r < 1/2, with increasing Kondo
correlations, in the presence of particle-hole symmetry this model exhibits a
quantum phase transition from a unscreened local moment (LM) phase to the Kondo
phase. Via a controlled frequency-dependent renormalization group (RG)
approach, we compute analytically and numerically the non-equilibrium
conductance, conduction electron T-matrix and local spin susceptibility at
finite bias voltages near criticality. The current-induced decoherence shows
distinct nonequilibrium scaling, leading to new universal non-equilibrium
quantum critical behaviors in the above observables. Relevance of our results
for the experiments is discussed.Comment: 4.1 pages, 2 figure
Cartan calculi on the quantum superplane
Cartan calculi on the extended quantum superplane are given. To this end, the
noncommutative differential calculus on the extended quantum superplane is
extended by introducing inner derivations and Lie derivatives
Trusted Hands: The Role of Community-Based Organizations in Enrolling Children in Public Health Insurance Programs
Trusted Hand is a new approach to enrolling traditionally hard-to-reach children in public health insurance programs. While the most common locations for enrollment assistance are state and local social service agencies and health clinics, many states are increasing their network to include a variety of community-based organizations that typically have not been involved in public health insurance. This Issue Brief, prepared by researchers at the University of Colorado Denver, details the advantages, as well as the challenges of this promising new strategy
The Neural Encoding of Cocaine-Induced Devaluation in The Ventral Pallidum
Cocaine experience affects motivation structures such as the nucleus accumbens (NAc) and its major output target, the ventral pallidum (VP). Previous studies demonstrated that both NAc activity and hedonic responses change reliably as a taste cue comes to predict cocaine availability. Here we extended this investigation to examine drug-experience induced changes in hedonic encoding in the VP. VP activity was first characterized in adult male Sprague–Dawley rats in response to intraoral infusions of palatable saccharin and unpalatable quinine solutions. Next, rats received 7 daily pairings of saccharin that predicted either a cocaine (20 mg/kg, ip) or saline injection. Finally, the responses to saccharin and quinine were again assessed. Of 109 units recorded in 11 rats that received saccharin–cocaine pairings, 71% of responsive units significantly reduced firing rate during saccharin infusions and 64% increased firing rate during quinine exposure. However, as saccharin came to predict cocaine, and elicited aversive taste reactivity, VP responses changed to resemble quinine. After conditioning, 70% of saccharin-responsive units increased firing rate. Most units that encoded the palatable taste (predominantly reduced firing rate) were located in the anterior VP, while most units that were responsive to aversive tastes were located in the posterior VP. This study reveals an anatomical complexity to the nature of hedonic encoding in the VP
Searching for Colorons at the Large Hadron Collider
We investigate the prospects for the discovery of massive color-octet vector
bosons at the CERN Large Hadron Collider with TeV. A
phenomenological Lagrangian is adopted to evaluate the cross section of a pair
of colored vector bosons (colorons, ) decaying into four colored
scalar resonances (hyper-pions, ), which then decay into eight
gluons. We include the dominant physics background from the production of
, and , and determine the masses of and
where discovery is possible. For example, we find that a
5 signal can be established for M_{\tilde{\pi}} \alt 495 GeV
(M_{\tilde{\rho}} \alt 1650 GeV). More generally we give the reach of this
process for a selection of possible cuts and integrated luminosities.Comment: REVTEX, 20 pages, 16 figure
Extraction of nuclear matter properties from nuclear masses by a model of equation of state
The extraction of nuclear matter properties from measured nuclear masses is
investigated in the energy density functional formalism of nuclei. It is shown
that the volume energy and the nuclear incompressibility depend
essentially on , whereas the symmetry energy
and the density symmetry coefficient as well as symmetry incompressibility
depend essentially on , where
, and are the
neutron and proton chemical potentials respectively, the nuclear energy,
and the Coulomb energy. The obtained symmetry energy is ,
while other coefficients are uncertain within ranges depending on the model of
nuclear equation of state.Comment: 12 pages and 7 figure
Non-equilibrium spatial distribution of Rashba spin torque in ferromagnetic metal layer
We study the spatial distribution of spin torque induced by a strong Rashba
spin-orbit coupling (RSOC) in a ferromagnetic (FM) metal layer, using the
Keldysh non-equilibrium Green's function method. In the presence of the s-d
interaction between the non-equilibrium conduction electrons and the local
magnetic moments, the RSOC effect induces a torque on the moments, which we
term as the Rashba spin torque.
A correlation between the Rashba spin torque and the spatial spin current is
presented in this work, clearly mapping the spatial distribution of Rashba Spin
torque in a nano-sized ferromagnetic device. When local magnetism is turned on,
the out-of-plane (Sz) Spin Hall effect (SHE) is disrupted, but rather
unexpectedly an in-plane (Sy) SHE is detected. We also study the effect of
Rashba strength (\alpha_R) and splitting exchange (\Delta) on the
non-equilibrium Rashba spin torque averaged over the device. Rashba spin torque
allows an efficient transfer of spin momentum such that a typical switching
field of 20 mT can be attained with a low current density of less than 10^6
A/cm^2
Erratum: Dynamics and scaling in a quantum spin chain material with bond randomness
Follow-up neutron measurements, performed on a sample much larger than the
one used in the original study, show that in the energy range 0.5-45 meV the
magnetic excitations in BaCu2SiGeO7 are indistinguishable from those in
conventional (disorder-free) quantum S=1/2 chains. Scrutinizing the previous
data, we found that the analysis was affected by a poorly identified structured
background and an additional technical mistake in the data reduction.Comment: This is a complete withdrawal of the original paper, also published
as in Phys. Rev. Lett 93, 077206 (2004). One page, one figur
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