6,581 research outputs found
Projecting the Kondo Effect: Theory of the Quantum Mirage
A microscopic theory is developed for the projection (quantum mirage) of the
Kondo resonance from one focus of an elliptic quantum corral to the other
focus. The quantum mirage is shown to be independent of the size and the shape
of the ellipse, and experiences \lambda_F/4 oscillations (\lambda_F is the
surface-band Fermi wavelength) with an increasing semimajor axis length. We
predict an oscillatory behavior of the mirage as a function of a weak magnetic
field applied perpendicular to the sample.Comment: 4 pages 2 figures include
Improving the lattice axial vector current
For Wilson and clover fermions traditional formulations of the axial vector
current do not respect the continuum Ward identity which relates the divergence
of that current to the pseudoscalar density. Here we propose to use a
point-split or one-link axial vector current whose divergence exactly satisfies
a lattice Ward identity, involving the pseudoscalar density and a number of
irrelevant operators. We check in one-loop lattice perturbation theory with
SLiNC fermion and gauge plaquette action that this is indeed the case including
order effects. Including these operators the axial Ward identity remains
renormalisation invariant. First preliminary results of a nonperturbative check
of the Ward identity are also presented.Comment: 7 pages, 3 figures, Proceedings of the 33rd International Symposium
on Lattice Field Theory, 14-18 July 2015, Kobe, Japa
Interacting Electrons and Localized Spins: Exact Results from Conformal Field Theory
We give a brief review of the Kondo effect in a one-dimensional interacting
electron system, and present exact results for the impurity thermodynamic
response based on conformal field theory.Comment: 6 pages LaTeX. To appear in the Proceedings of the 1995 Schladming
Winter School on Low-Dimensional Models in Statistical Physics and Quantum
Field Theor
Renormalization of local quark-bilinear operators for Nf=3 flavors of SLiNC fermions
The renormalization factors of local quark-bilinear operators are computed
non-perturbatively for flavors of SLiNC fermions, with emphasis on the
various procedures for the chiral and continuum extrapolations. The simulations
are performed at a lattice spacing fm, and for five values of the
pion mass in the range of 290-465 MeV, allowing a safe and stable chiral
extrapolation. Emphasis is given in the subtraction of the well-known pion pole
which affects the renormalization factor of the pseudoscalar current. We also
compute the inverse propagator and the Green's functions of the local bilinears
to one loop in perturbation theory. We investigate lattice artifacts by
computing them perturbatively to second order as well as to all orders in the
lattice spacing. The renormalization conditions are defined in the RI-MOM
scheme, for both the perturbative and non-perturbative results. The
renormalization factors, obtained at different values of the renormalization
scale, are translated to the scheme and are evolved
perturbatively to 2 GeV. Any residual dependence on the initial renormalization
scale is eliminated by an extrapolation to the continuum limit. We also study
the various sources of systematic errors.
Particular care is taken in correcting the non-perturbative estimates by
subtracting lattice artifacts computed to one loop perturbation theory using
the same action. We test two different methods, by subtracting either the
contributions, or the complete (all orders in )
one-loop lattice artifacts.Comment: 33 pages, 27 figures, 6 table
Thermal and electromagnetic properties of 166-Er and 167-Er
The primary gamma-ray spectra of 166-Er and 167-Er are deduced from the
(3-He,alpha gamma) and (3-He,3-He' gamma) reaction, respectively, enabling a
simultaneous extraction of the level density and the gamma-ray strength
function. Entropy, temperature and heat capacity are deduced from the level
density within the micro-canonical and the canonical ensemble, displaying
signals of a phase-like transition from the pair-correlated ground state to an
uncorrelated state at Tc=0.5 MeV. The gamma-ray strength function displays a
bump around E-gamma=3 MeV, interpreted as the pygmy resonance.Comment: 21 pages including 2 tables and 11 figure
Observation of twin beam correlations and quadrature entanglement by frequency doubling in a two-port resonator
We demonstrate production of quantum correlated and entangled beams by second
harmonic generation in a nonlinear resonator with two output ports. The output
beams at wavelength 428.5 nm exhibit 0.9 dB of nonclassical intensity
correlations and 0.3 dB of entanglement.Comment: 5 pages, 7 figure
The operator product expansion on the lattice
We investigate the Operator Product Expansion (OPE) on the lattice by
directly measuring the product (where J is the vector current) and
comparing it with the expectation values of bilinear operators. This will
determine the Wilson coefficients in the OPE from lattice data, and so give an
alternative to the conventional methods of renormalising lattice structure
function calculations. It could also give us access to higher twist quantities
such as the longitudinal structure function F_L = F_2 - 2 x F_1. We use overlap
fermions because of their improved chiral properties, which reduces the number
of possible operator mixing coefficients.Comment: 7 pages, 4 postscript figures. Contribution to Lattice 2007,
Regensbur
A lattice determination of Sigma - Lambda mixing
Isospin breaking effects in baryon octet (and decuplet) masses are due to a
combination of up and down quark mass differences and electromagnetic effects
and lead to small mass splittings. Between the Sigma and Lambda this mass
splitting is much larger, this being mostly due to their different
wavefunctions. However when isospin is broken, there is a mixing between
between these states. We describe the formalism necessary to determine the QCD
mixing matrix and hence find the mixing angle and mass splitting between the
Sigma and Lambda particles due to QCD effects.Comment: 40 pages, 5 figures, published versio
Surface-enhanced Raman encoded polymer stabilized gold nanoparticles : demonstration of potential for use in bioassays
The preparation of biotinylated, self-assembled polymer stabilized gold nanoparticle hybrids encoded with a SERS active compound is described. The polymers used for nanoparticle stabilization are carefully designed for this purpose and are synthesized by the RAFT polymerization process, as the thiocarbonylthio end group provides a functional handle for anchoring the polymers to the gold surface. Functionalized biotin moieties are attached to the hybrid nanoparticles via Cu-catalyzed azide-alkyne cycloaddition. Binding of the biotinylated hybrid nanoparticles to streptavidin was confirmed by nanoparticle detection and identification by the SERS spectrum of the surface-bound SERS active compound, quinoline thiol. This investigation includes the requisites that constitute a bioassay, demonstrating the potential of polymer-coated hybrid nanoparticles for this purpose
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