37,130 research outputs found
Point interactions in one dimension and holonomic quantum fields
We introduce and study a family of quantum fields, associated to
delta-interactions in one dimension. These fields are analogous to holonomic
quantum fields of M. Sato, T. Miwa and M. Jimbo. Corresponding field operators
belong to an infinite-dimensional representation of the group SL(2,\Rb) in
the Fock space of ordinary harmonic oscillator. We compute form factors of such
fields and their correlation functions, which are related to the determinants
of Schroedinger operators with a finite number of point interactions. It is
also shown that these determinants coincide with tau functions, obtained
through the trivialization of the -bundle over a Grassmannian
associated to a family of Schroedinger operators.Comment: 17 page
Similarity of Fermi Surface in the Hidden Order State and in the Antiferromagnetic State of URu2Si2
Shubnikov-de Haas measurements of high quality URu2Si2 single crystals reveal
two previously unobserved Fermi surface branches in the so-called hidden order
phase. Therefore about 55% of the enhanced mass is now detected. Under pressure
in the antiferromagnetic state, the Shubnikov-de Haas frequencies for magnetic
fields applied along the crystalline c axis show little change compared with
the zero pressure data. This implies a similar Fermi surface in both the hidden
order and antiferromagnetic states, which strongly suggests that the lattice
doubling in the antiferromagnetic phase due to the ordering vector QAF = (0 0
1) already occurs in the hidden order. These measurements provide a good test
for existing or future theories of the hidden order parameter.Comment: 4 pages, 4 figure
Surface Effects on the Mechanical Elongation of AuCu Nanowires: De-alloying and the Formation of Mixed Suspended Atomic Chains
We report here an atomistic study of the mechanical deformation of AuxCu(1-x)
atomic-size wires (NWs) by means of high resolution transmission electron
microscopy (HRTEM) experiments. Molecular dynamics simulations were also
carried out in order to obtain deeper insights on the dynamical properties of
stretched NWs. The mechanical properties are significantly dependent on the
chemical composition that evolves in time at the junction; some structures
exhibit a remarkable de-alloying behavior. Also, our results represent the
first experimental realization of mixed linear atomic chains (LACs) among
transition and noble metals; in particular, surface energies induce chemical
gradients on NW surfaces that can be exploited to control the relative LAC
compositions (different number of gold and copper atoms). The implications of
these results for nanocatalysis and spin transport of one-atom-thick metal
wires are addressed.Comment: Accepted to Journal of Applied Physics (JAP
Four-spin-exchange- and magnetic-field-induced chiral order in two-leg spin ladders
We propose a mechanism of a vector chiral long-range order in two-leg
spin-1/2 and spin-1 antiferromagnetic ladders with four-spin exchanges and a
Zeeman term. It is known that for one-dimensional quantum systems, spontaneous
breakdown of continuous symmetries is generally forbidden. Any vector chiral
order hence does not appear in spin-rotationally [SU(2)]-symmetric spin
ladders. However, if a magnetic field is added along the S^z axis of ladders
and the SU(2) symmetry is reduced to the U(1) one, the z component of a vector
chiral order can emerge with the remaining U(1) symmetry unbroken. Making use
of Abelian bosonization techniques, we actually show that a certain type of
four-spin exchange can yield a vector chiral long-range order in spin-1/2 and
spin-1 ladders under a magnetic field. In the chiral-ordered phase, the Z_2
interchain-parity (i.e., chain-exchange) symmetry is spontaneously broken. We
also consider effects of perturbations breaking the parity symmetry.Comment: 8 pages, 1 figure, RevTex, published versio
On correlation functions of integrable models associated to the six-vertex R-matrix
We derive an analog of the master equation obtained recently for correlation
functions of the XXZ chain for a wide class of quantum integrable systems
described by the R-matrix of the six-vertex model, including in particular
continuum models. This generalized master equation allows us to obtain multiple
integral representations for the correlation functions of these models. We
apply this method to derive the density-density correlation functions of the
quantum non-linear Schrodinger model.Comment: 21 page
Mass spectrum from stochastic Levy-Schroedinger relativistic equations: possible qualitative predictions in QCD
Starting from the relation between the kinetic energy of a free
Levy-Schroedinger particle and the logarithmic characteristic of the underlying
stochastic process, we show that it is possible to get a precise relation
between renormalizable field theories and a specific Levy process. This
subsequently leads to a particular cut-off in the perturbative diagrams and can
produce a phenomenological mass spectrum that allows an interpretation of
quarks and leptons distributed in the three families of the standard model.Comment: 8 pages, no figures. arXiv admin note: substantial text overlap with
arXiv:1008.425
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