271 research outputs found
Quantum Transport in Two-Channel Fractional Quantum Hall Edges
We study the effect of backward scatterings in the tunneling at a point
contact between the edges of a second level hierarchical fractional quantum
Hall states. A universal scaling dimension of the tunneling conductance is
obtained only when both of the edge channels propagate in the same direction.
It is shown that the quasiparticle tunneling picture and the electron tunneling
picture give different scaling behaviors of the conductances, which indicates
the existence of a crossover between the two pictures. When the direction of
two edge-channels are opposite, e.g. in the case of MacDonald's edge
construction for the state, the phase diagram is divided into two
domains giving different temperature dependence of the conductance.Comment: 21 pages (REVTeX and 1 Postscript figure
Low-temperature nonequilibrium transport in a Luttinger liquid
The temperature-dependent nonlinear conductance for transport of a Luttinger
liquid through a barrier is calculated in the nonperturbative regime for
, where is the dimensionless interaction constant. To
describe the low-energy behavior, we perform a leading-log summation of all
diagrams contributing to the conductance which is valid for .
With increasing external voltage, the asymptotic low-temperature behavior
displays a turnover from the to a universal law.Comment: 13 pages RevTeX 3.0, accepted by Physical Review
Exact perturbative solution of the Kondo problem
We explicitly evaluate the infinite series of integrals that appears in the
"Anderson-Yuval" reformulation of the anisotropic Kondo problem in terms of a
one-dimensional Coulomb gas. We do this by developing a general approach
relating the anisotropic Kondo problem of arbitrary spin with the boundary
sine-Gordon model, which describes impurity tunneling in a Luttinger liquid and
in the fractional quantum Hall effect. The Kondo solution then follows from the
exact perturbative solution of the latter model in terms of Jack polynomials.Comment: 4 pages in revtex two-colum
A study of a wire-plate eletrostatic precipitator operating in the removal of polydispersed particles
Equivalence between Bell inequalities and quantum Minority game
We show that, for a continuous set of entangled four-partite states, the task
of maximizing the payoff in the symmetric-strategy four-player quantum Minority
game is equivalent to maximizing the violation of a four-particle Bell
inequality with each observer choosing the same set of two dichotomic
observables. We conclude the existence of direct correspondences between (i)
the payoff rule and Bell inequalities, and (ii) the strategy and the choice of
measured observables in evaluating these Bell inequalities. We also show that
such a correspondence between Bell polynomials (in a single plane) and
four-player, symmetric, binary-choice quantum games is unique to the
four-player quantum Minority game and its "anti-Minority" version. This
indicates that the four-player Minority game not only plays a special role
among quantum games but also in studies of Bell-type quantum nonlocality.Comment: v1 4 pages ReTeX, 2 figures (1 EPS); v2 11 pages LateX, 2 figures,
changes to format, minor changes to wording (including title) and one new
finding added on uniqueness of resul
Image-guided adaptive brachytherapy (IGABT) for primary vaginal cancer: results of the international multicenter RetroEMBRAVE cohort study.
Biological, physical and clinical aspects of cancer treatment with ionising radiatio
Non-zero temperature transport near quantum critical points
We describe the nature of charge transport at non-zero temperatures ()
above the two-dimensional () superfluid-insulator quantum critical point. We
argue that the transport is characterized by inelastic collisions among
thermally excited carriers at a rate of order . This implies that
the transport at frequencies is in the hydrodynamic,
collision-dominated (or `incoherent') regime, while is
the collisionless (or `phase-coherent') regime. The conductivity is argued to
be times a non-trivial universal scaling function of , and not independent of , as has been previously
claimed, or implicitly assumed. The experimentally measured d.c. conductivity
is the hydrodynamic limit of this function, and is a
universal number times , even though the transport is incoherent.
Previous work determined the conductivity by incorrectly assuming it was also
equal to the collisionless limit of the scaling
function, which actually describes phase-coherent transport with a conductivity
given by a different universal number times . We provide the first
computation of the universal d.c. conductivity in a disorder-free boson model,
along with explicit crossover functions, using a quantum Boltzmann equation and
an expansion in . The case of spin transport near quantum
critical points in antiferromagnets is also discussed. Similar ideas should
apply to the transitions in quantum Hall systems and to metal-insulator
transitions. We suggest experimental tests of our picture and speculate on a
new route to self-duality at two-dimensional quantum critical points.Comment: Feedback incorporated into numerous clarifying remarks; additional
appendix discusses relationship to transport in dissipative quantum mechanics
and quantum Hall edge state tunnelling problems, stimulated by discussions
with E. Fradki
Development of functionally selective, small molecule agonists at kappa opioid receptors
The kappa opioid receptor (KOR) is widely expressed in the CNS and can serve as a means to modulate pain perception, stress responses, and affective reward states. Therefore, the KOR has become a prominent drug discovery target toward treating pain, depression, and drug addiction. Agonists at KOR can promote G protein coupling and ÎČarrestin2 recruitment as well as multiple downstream signaling pathways, including ERK1/2 MAPK activation. It has been suggested that the physiological effects ofKORactivation result from different signaling cascades, with analgesia being G protein-mediated and dysphoria being mediated through ÎČarrestin2 recruitment. Dysphoria associated with KOR activation limits the therapeutic potential in the use of KOR agonists as analgesics; therefore, it may be beneficial to develop KOR agonists that are biased toward G protein coupling and away from ÎČarrestin2 recruitment. Here, we describe two classes of biased KOR agonists that potently activateGprotein coupling but weakly recruitÎČarrestin2. These potent and functionally selective small molecule compounds may prove to be useful tools for refining the therapeutic potential of KOR-directed signaling in vivo
Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment
This paper describes an analysis of the angular distribution of W->enu and
W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with
the ATLAS detector at the LHC in 2010, corresponding to an integrated
luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and
the missing transverse energy, the W decay angular distribution projected onto
the transverse plane is obtained and analysed in terms of helicity fractions
f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV
and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw
> 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour,
are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017
+/- 0.030, where the first uncertainties are statistical, and the second
include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables,
revised author list, matches European Journal of Physics C versio
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