7,808 research outputs found
The Gauge-Bethe Correspondence and Geometric Representation Theory
The Gauge/Bethe correspondence of Nekrasov and Shatashvili relates the
spectrum of integrable spin chains to the ground states of supersymmetric gauge
theories. Up to now, this correspondence has been an observation; the
underlying reason for its existence remaining elusive. We argue here that
geometrical representation theory is the mathematical foundation of the
Gauge/Bethe correspondence, and it provides a framework to study families of
gauge theories in a unified way.Comment: 8 page
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Tropidophis hendersoni
Number of Pages: 8Integrative BiologyGeological Science
Recommended from our members
Leiocephalus onaneyi
Number of pages: 7Geological SciencesIntegrative Biolog
The X-ray cycle in the solar-type star HD 81809
(abridged) Our long-term XMM-Newton program of long-term monitoring of a
solar-like star with a well-studied chromospheric cycle, HD 81809 aims to study
whether an X-ray cycle is present, along with studying its characteristics and
its relation to the chromospheric cycle. Regular observations of HD 81809 were
performed with XMM-Newton, spaced by 6 months from 2001 to 2007. We studied the
variations in the resulting coronal luminosity and temperature, and compared
them with the chromospheric CaII variations. We also modeled the observations
in terms of a mixture of active regions, using a methodology originally
developed to study the solar corona. Our observations show a well-defined cycle
with an amplitude exceeding 1 dex and an average luminosity approximately one
order of magnitude higher than in the Sun. The behavior of the corona of HD
81809 can be modeled well in terms of varying coverage of solar-like active
regions, with a larger coverage than for the Sun, showing it to be compatible
with a simple extension of the solar case.Comment: In press, Astronomy & Astrophysic
Quantum Nondemolition Charge Measurement of a Josephson Qubit
In a qubit system, the measurement operator does not necessarily commute with
the qubit Hamiltonian, so that the readout process demolishes (mixes) the qubit
energy eigenstates. The readout time is therefore limited by such a mixing time
and its fidelity will be reduced. A quantum nondemolition readout scheme is
proposed in which the charge of a flux qubit is measured. The measurement
operator is shown to commute with the qubit Hamiltonian in the reduced
two-level Hilbert space, even though the Hamiltonian contains non-commuting
charge and flux terms.Comment: 4 pages, 3 figures, a paragraph added to describe how the scheme
works in charge regim
Static and dynamic properties of Single-Chain Magnets with sharp and broad domain walls
We discuss time-quantified Monte-Carlo simulations on classical spin chains
with uniaxial anisotropy in relation to static calculations. Depending on the
thickness of domain walls, controlled by the relative strength of the exchange
and magnetic anisotropy energy, we found two distinct regimes in which both the
static and dynamic behavior are different. For broad domain walls, the
interplay between localized excitations and spin waves turns out to be crucial
at finite temperature. As a consequence, a different protocol should be
followed in the experimental characterization of slow-relaxing spin chains with
broad domain walls with respect to the usual Ising limit.Comment: 18 pages, 13 figures, to be published in Phys. Rev.
Discreteness-induced resonances and AC voltage amplitudes in long one-dimensional Josephson junction arrays
New resonance steps are found in the experimental current-voltage
characteristics of long, discrete, one-dimensional Josephson junction arrays
with open boundaries and in an external magnetic field. The junctions are
underdamped, connected in parallel, and DC biased. Numerical simulations based
on the discrete sine-Gordon model are carried out, and show that the solutions
on the steps are periodic trains of fluxons, phase-locked by a finite amplitude
radiation. Power spectra of the voltages consist of a small number of harmonic
peaks, which may be exploited for possible oscillator applications. The steps
form a family that can be numbered by the harmonic content of the radiation,
the first member corresponding to the Eck step. Discreteness of the arrays is
shown to be essential for appearance of the higher order steps. We use a
multi-mode extension of the harmonic balance analysis, and estimate the
resonance frequencies, the AC voltage amplitudes, and the theoretical limit on
the output power on the first two steps.Comment: REVTeX, 17 pages, 7 figures, psfig; to appear in J. Applied Physic
Cytological Observations on Pselaphid Beetles
Author Institution: Department of Biological Sciences, Northwestern University, Evanston, Illinoi
Twisted Masses and Enhanced Symmetries: the A&D Series
We study new symmetries between A and D type quiver gauge theories with
different numbers of colors. We realize these gauge theories with twisted
masses via a brane construction that reproduces all the parameters of the
Gauge/Bethe correspondence.Comment: 14 pages, 5 figure
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