8,117 research outputs found
Differential Regularization of a Non-relativistic Anyon Model
Differential regularization is applied to a field theory of a
non-relativistic charged boson field with
self-interaction and coupling to a statistics-changing Chern-Simons
gauge field. Renormalized configuration-space amplitudes for all diagrams
contributing to the 4-point function, which
is the only primitively divergent Green's function, are obtained up to 3-loop
order. The renormalization group equations are explicitly checked, and the
scheme dependence of the -function is investigated. If the
renormalization scheme is fixed to agree with a previous 1-loop calculation,
the 2- and 3-loop contributions to vanish, and
itself vanishes when the ``self-dual'' condition relating
to the gauge coupling is imposed.Comment: 22 pages in ReVTEX (with a plaintext PostScript figure appended at
end), MIT CTP #221
On the number of representations providing noiseless subsystems
This paper studies the combinatoric structure of the set of all
representations, up to equivalence, of a finite-dimensional semisimple Lie
algebra. This has intrinsic interest as a previously unsolved problem in
representation theory, and also has applications to the understanding of
quantum decoherence. We prove that for Hilbert spaces of sufficiently high
dimension, decoherence-free subspaces exist for almost all representations of
the error algebra. For decoherence-free subsystems, we plot the function
which is the fraction of all -dimensional quantum systems which
preserve bits of information through DF subsystems, and note that this
function fits an inverse beta distribution. The mathematical tools which arise
include techniques from classical number theory.Comment: 17 pp, 4 figs, accepted for Physical Review
The Three Loop Equation of State of QED at High Temperature
We present the three loop contribution (order ) to the pressure of
massless quantum electrodynamics at nonzero temperature. The calculation is
performed within the imaginary time formalism. Dimensional regularization is
used to handle the usual, intermediate stage, ultraviolet and infrared
singularities, and also to prevent overcounting of diagrams during resummation.Comment: ANL-HEP-PR-94-02, SPhT/94-054 (revised final version
Late-time structure of the Bunch-Davies de Sitter wavefunction
We examine the late time behavior of the Bunch-Davies wavefunction for interacting light fields in a de Sitter background. We use perturbative techniques developed in the framework of AdS/CFT, and analytically continue to compute tree and loop level contributions to the Bunch-Davies wavefunction. We consider self-interacting scalars of general mass, but focus especially on the massless and conformally coupled cases. We show that certain contributions grow logarithmically in conformal time both at tree and loop level. We also consider gauge fields and gravitons. The four-dimensional Fefferman-Graham expansion of classical asymptotically de Sitter solutions is used to show that the wavefunction contains no logarithmic growth in the pure graviton sector at tree level. Finally, assuming a holographic relation between the wavefunction and the partition function of a conformal field theory, we interpret the logarithmic growths in the language of conformal field theory
Exact Topological Quantum Order in D=3 and Beyond: Branyons and Brane-Net Condensates
We construct an exactly solvable Hamiltonian acting on a 3-dimensional
lattice of spin- systems that exhibits topological quantum order.
The ground state is a string-net and a membrane-net condensate. Excitations
appear in the form of quasiparticles and fluxes, as the boundaries of strings
and membranes, respectively. The degeneracy of the ground state depends upon
the homology of the 3-manifold. We generalize the system to , were
different topological phases may occur. The whole construction is based on
certain special complexes that we call colexes.Comment: Revtex4 file, color figures, minor correction
A Cluster of Class I/f/II YSOs Discovered Near the Cepheid SU Cas
Preliminary constraints are placed on a cluster of YSOs (J2000 02:54:31.4
+69:20:32.5) discovered in the field of the classical Cepheid SU Cas. WISE 3.4,
4.6, 12, and 22 um images reveal that the cluster deviates from spherical
symmetry and exhibits an apparent diameter of 3x6'. SEDs constructed using
2MASS Ks (2.2 um) and WISE photometry indicate that 19 (36%) class I, 21 (40%)
class f, and 13 (25%) class II objects lie r<3' from the cluster center.
Conversely, 11 (18%) class I, 13 (21%) class f, and 37 (61%) class II objects
were detected for r>3'. Approximately 50% of the class I sources within r<3'
were classified solely using WISE photometry owing to the absence of detections
by 2MASS.Comment: Accepted for Publication (MNRAS
Assertiveness Training and Exposure In Vivo for Agoraphobics
The effectiveness of brief treatment via assertiveness training and exposure in vivo was evaluated in a crossover study of eight agoraphobics. Treatment brought short-term benefit as assessed by phobia questionnaires and a depression inventory, but assertiveness training did not. Conversely, assertiveness training produced short-term improvements as measured by an assertiveness inventory, while exposure treatment did not. Both treatments were relevant to the problems of our client sample, but they had specific effects on measures closely related to each treatment\u27s target, consistent with the results of a similar recent study by Emmelkamp et al. (1983). At six-month follow-up assessment, phobia questionnaire scores were unchanged from post-treatment assessment, but assertion scores had reverted to pre-treatment levels. In addition, five untreated agoraphobics completed phobia questionnaires on two occasions, six months apart. In a quasi-experiment, their scores on the two occasions were compared with treated clients\u27 pre- and post-treatment scores. Treated clients showed significantly greater improvement, demonstrating the sensitivity of the questionnaires to treatment effects
Differential Regularization of Topologically Massive Yang-Mills Theory and Chern-Simons Theory
We apply differential renormalization method to the study of
three-dimensional topologically massive Yang-Mills and Chern-Simons theories.
The method is especially suitable for such theories as it avoids the need for
dimensional continuation of three-dimensional antisymmetric tensor and the
Feynman rules for three-dimensional theories in coordinate space are relatively
simple. The calculus involved is still lengthy but not as difficult as other
existing methods of calculation. We compute one-loop propagators and vertices
and derive the one-loop local effective action for topologically massive
Yang-Mills theory. We then consider Chern-Simons field theory as the large mass
limit of topologically massive Yang-Mills theory and show that this leads to
the famous shift in the parameter . Some useful formulas for the calculus of
differential renormalization of three-dimensional field theories are given in
an Appendix.Comment: 25 pages, 4 figures. Several typewritten errors and inappropriate
arguments are corrected, especially the correct adresses of authors are give
- …