9,605 research outputs found
On complexes related with calculus of variations
We consider the variational complex on infinite jet space and the complex of
variational derivatives for Lagrangians of multidimensional paths and study
relations between them. The discussion of the variational (bi)complex is set up
in terms of a flat connection in the jet bundle. We extend it to supercase
using a particular new class of forms. We establish relation of the complex of
variational derivatives and the variational complex. Certain calculus of
Lagrangians of multidimensional paths is developed. It is shown how covariant
Lagrangians of higher order can be used to represent characteristic classes.Comment: LaTeX2e, 36 page
Preparing projected entangled pair states on a quantum computer
We present a quantum algorithm to prepare injective PEPS on a quantum
computer, a class of open tensor networks representing quantum states. The
run-time of our algorithm scales polynomially with the inverse of the minimum
condition number of the PEPS projectors and, essentially, with the inverse of
the spectral gap of the PEPS' parent Hamiltonian.Comment: 5 pages, 1 figure. To be published in Physical Review Letters.
Removed heuristics, refined run-time boun
Duality Symmetry in the Schwarz-Sen Model
The continuous extension of the discrete duality symmetry of the Schwarz-Sen
model is studied. The corresponding infinitesimal generator turns out to be
local, gauge invariant and metric independent. Furthermore, commutes with
all the conformal group generators. We also show that is equivalent to the
non---local duality transformation generator found in the Hamiltonian
formulation of Maxwell theory. We next consider the Batalin--Fradkin-Vilkovisky
formalism for the Maxwell theory and demonstrate that requiring a local duality
transformation lead us to the Schwarz--Sen formulation. The partition functions
are shown to be the same which implies the quantum equivalence of the two
approaches.Comment: 10 pages, latex, small changes, final version to appear in Phys. Rev.
On Duality in the Born-Infeld Theory
The duality symmetric action for the Born-Infeld theory in terms of
two potentials, coupled with non-trivial backgroud fields in four dimensions is
established. This construction is carried out in detail by analysing the
hamiltonian structure of the Born-Infeld theory. The equivalence with the usual
Born-Infeld theory is shown.Comment: revtex, 4 page
Dense Ionized and Neutral Gas Surrounding Sgr A*
We present high resolution H41a hydrogen recombination line observations of
the 1.2' (3 pc) region surrounding Sgr A* at 92 GHz using the OVRO Millimeter
Array with an angular resolution of 7" x 3" and velocity resolution of 13 km/s.
New observations of H31a, H35a, H41a, and H44a lines were obtained using the
NRAO 12-m telescope, and their relative line strengths are interpreted in terms
of various emission mechanisms. These are the most extensive and most sensitive
observations of recombination line to date. Observations of HCO+ (1 - 0)
transition at 89 GHz are also obtained simultaneously with a 40% improved
angular resolution and 4-15 times improved sensitivity over previous
observations, and the distribution and kinematics of the dense molecular gas in
the circumnuclear disk (CND) are mapped and compared with those of the ionized
gas. The line brightness ratios of the hydrogen recombination lines are
consistent with purely spontaneous emission from 7000 K gas with n_e = 20,000
cm near LTE condition. A virial analysis suggests that the most
prominent molecular gas clumps in the CND have mean densities of 10^7 cm^{-3},
sufficient to withstand the tidal shear in the Galactic Center region.
Therefore, these clumps may survive over several dynamical times, and the CND
may be a dynamically stable structure. We estimate a total gas mass of 3 x 10^5
solar mass for the CND. \Comment: 34 pages including 11 figures (4 jpgs), Latex, uses aastex. The full
pdf format file including high resolution figures is available at
http://www.astro.umass.edu/~myun/papers/SgrA.pdf . To appear in the 20
November 2004 (V616) issue of the Astrophysical Journa
Non Abelian TQFT and scattering of self dual field configuration
A non-abelian topological quantum field theory describing the scattering of
self-dual field configurations over topologically non-trivial Riemann surfaces,
arising from the reduction of 4-dim self-dual Yang-Mills fields, is introduced.
It is shown that the phase space of the theory can be exactly quantized in
terms of the space of holomorphic structures over stable vector bundles of
degree zero over Riemann surfaces. The Dirac monopoles are particular static
solutions of the field equations. Its relation to topological gravity is
discussed.Comment: 13 pages, Late
Poincare Invariance of a Quantized Duality Symmetric Theory
The noncovariant duality symmetric action put forward by Schwarz-Sen is
quantized by means of the Dirac bracket quantization procedure. The resulting
quantum theory is shown to be, nevertheless, relativistically invariant
Lattice QCD and the Schwarz alternating procedure
A numerical simulation algorithm for lattice QCD is described, in which the
short- and long-distance effects of the sea quarks are treated separately. The
algorithm can be regarded, to some extent, as an implementation at the quantum
level of the classical Schwarz alternating procedure for the solution of
elliptic partial differential equations. No numerical tests are reported here,
but theoretical arguments suggest that the algorithm should work well also at
small quark masses.Comment: Plain TeX source, 20 pages, figures include
Macrophage Polarization is Deregulated in Haemophilia
Macrophages make important contributions to inflammation and wound healing. We
show here that macrophage polarization is deregulated in haemophilia in response to
macrophage colony-stimulating factor (M-CSF) and partially in response to granulocyte-macrophage colony-stimulating factor (GM-CSF). As a result, haemophilia macrophages exhibit a specific impairment of M-CSF-mediated functions involved in wound
healing such as clot invasion and phagocytosis. Haemophilia monocytes express
reduced amounts of the receptors for M-CSF and GM-CSF, which correlates with a
failure to express tumour necrosis factor α (TNFα) and CD163 in M-CSF-treated
haemophilia macrophages and reduced expression of TNFα and CD206 after treatment
with GM-CSF. Protein expression in response to M-CSF was regained with respect to
CD163 and CD206 after embedding haemophilia monocytes in clotted plasma
suggesting that a functioning coagulation system has positive effects on macrophage
M2 polarization. Mimicking the functional deficits of haemophilia macrophages in
normal macrophages was possible by adding leptin, which we found to be elevated in
the blood of haemophilia patients, to a monocyte cell line. The increase of leptin
occurred in conjunction with C-reactive protein in a body mass index-controlled cohort
suggesting that haemophilia patients harbour chronic low-grade inflammation.
Together, our data indicate that impaired clotting in haemophilia patients leads to
increased inflammation and a deregulation in macrophage differentiation, which may
explain the commonly observed deficits in wound healing and tissue regeneration
Classification of N=6 superconformal theories of ABJM type
Studying the supersymmetry enhancement mechanism of Aharony, Bergman,
Jafferis and Maldacena, we find a simple condition on the gauge group
generators for the matter fields. We analyze all possible compact Lie groups
and their representations. The only allowed gauge groups leading to the
manifest N=6 supersymmetry are, up to discrete quotients, SU(n) x U(1), Sp(n) x
U(1), SU(n) x SU(n), and SU(n) x SU(m) x U(1) with possibly additional U(1)'s.
Matter representations are restricted to be the (bi)fundamentals. As a
byproduct we obtain another proof of the complete classification of the three
algebras considered by Bagger and Lambert.Comment: 18 page
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