5,082 research outputs found
Ectoplasm & Superspace Integration Measure for 2D Supergravity with Four Spinorial Supercurrents
Building on a previous derivation of the local chiral projector for a two
dimensional superspace with eight real supercharges, we provide the complete
density projection formula required for locally supersymmetrical theories in
this context. The derivation of this result is shown to be very efficient using
techniques based on the Ectoplasmic construction of local measures in
superspace.Comment: 18 pages, LaTeX; V2: minor changes, typos corrected, references
added; V3: version to appear in J. Phys. A: Math. Theor., some comments and
references added to address a referee reques
On 2D N=(4,4) superspace supergravity
We review some recent results obtained in studying superspace formulations of
2D N=(4,4) matter-coupled supergravity. For a superspace geometry described by
the minimal supergravity multiplet, we first describe how to reduce to
components the chiral integral by using ``ectoplasm'' superform techniques as
in arXiv:0907.5264 and then we review the bi-projective superspace formalism
introduced in arXiv:0911.2546. After that, we elaborate on the curved
bi-projective formalism providing a new result: the solution of the covariant
type-I twisted multiplet constraints in terms of a weight-(-1,-1) bi-projective
superfield.Comment: 18 pages, LaTeX, Contribution to the proceedings of the International
Workshop "Supersymmetries and Quantum Symmetries" (SQS'09), Dubna, July
29-August 3 200
Quantizing N=2 matter-supergravity systems
We consider supergravity coupled to Yang--Mills matter and
discuss the nature of one--loop divergences. Using superfields and
superspace methods, we describe the quantization of the system in the abelian
case.Comment: 18 pages, late
Consistent two--dimensional chiral gravity
We study chiral induced gravity in the light-cone gauge and show that the
theory is consistent for a particular choice of chiralities. The corresponding
Kac--Moody central charge has no forbidden region of complex values.
Generalized analysis of the critical exponents is given and their relation to
the vacuum states is elucidated. All the parameters containing
information about the theory can be traced back to the characteristics of the
group of residual symmetry in the light--cone gauge.Comment: 38 pages, LateX, to appear in Int.J.Mod.Phys.
Spectral energy distributions of quasars selected in the mid-infrared
We present preliminary results on fitting of SEDs to 142 z>1 quasars selected
in the mid-infrared. Our quasar selection finds objects ranging in extinction
from highly obscured, type-2 quasars, through more lightly reddened type-1
quasars and normal type-1s. We find a weak tendency for the objects with the
highest far-infrared emission to be obscured quasars, but no bulk systematic
offset between the far-infrared properties of dusty and normal quasars as might
be expected in the most naive evolutionary schemes. The hosts of the type-2
quasars have stellar masses comparable to those of radio galaxies at similar
redshifts. Many of the type-1s, and possibly one of the type-2s require a very
hot dust component in addition to the normal torus emission.Comment: 4 pages, 2 figures, to appear in the proceedings of The Spectral
Energy Distribution of Galaxies, Preston, September 2011, eds R.J. Tuffs &
C.C. Popesc
The effect of thermal annealing on the properties of Al-AlOx-Al single electron tunneling transistors
The effect of thermal annealing on the properties of Al-AlOx-Al single
electron tunneling transistors is reported. After treatment of the devices by
annealing processes in forming gas atmosphere at different temperatures and for
different times, distinct and reproducible changes of their resistance and
capacitance values were found. According to the temperature regime, we observed
different behaviors as regards the resistance changes, namely the tendency to
decrease the resistance by annealing at T = 200 degree C, but to increase the
resistance by annealing at T = 400 degree C. We attribute this behavior to
changes in the aluminum oxide barriers of the tunnel junctions. The good
reproducibility of these effects with respect to the changes observed allows
the proper annealing treatment to be used for post-process tuning of tunnel
junction parameters. Also, the influence of the annealing treatment on the
noise properties of the transistors at low frequency was investigated. In no
case did the noise figures in the 1/f-regime show significant changes.Comment: 6 pages, 7 eps-figure
Quantum cosmology in the models of 2d and 4d dilatonic supergravity with WZ matter
We consider N=1 two-dimensional (2d) dilatonic supergravity (SG), 2d
dilatonic SG obtained by dimensional reduction from N=1 four-dimensional (4d)
SG, N=2 2d dilatonic SG and string-inspired 4d dilatonic SG. For all the
theories, the corresponding action on a bosonic background is constructed and
the interaction with (dilatonic) Wess-Zumino (WZ) multiplets is presented.
Working in the large-N approximation, it is enough to consider the trace
anomaly induced effective action due to dilaton-coupled conformal matter as a
quantum correction (for 2d models s-waves approximation is additionally used).
The equations of motion for all such models with quantum corrections are
written in a form convenient for numerical analysis. Their solutions are
numerically investigated for 2d and 4d Friedmann-Robertson-Walker (FRW) or 4d
Kantowski-Sacks Universes with a time-dependent dilaton via exponential dilaton
coupling. The evolution of the corresponding quantum cosmological models is
given for different choices of initial conditions and theory parameters. In
most cases we find quantum singular Universes. Nevertheless, there are examples
of Universe non-singular at early times. Hence, it looks unlikely that quantum
matter back reaction on dilatonic background (at least in large
approximation) may really help to solve the singularity problem.Comment: LaTeX file of the text (36 pages) and 3 ps files of 14 figures, few
misprints are corrected and references adde
INSTANTON CALCULATIONS VERSUS EXACT RESULTS IN 4 DIMENSIONAL SUSY GAUGE THEORIES.
We relate the non-perturbative exact results in supersymmetry to perturbation
theory using several different methods: instanton calculations at weak or
strong coupling, a method using gaugino condensation and another method
relating strong and weak coupling. This allows many precise numerical checks of
the consistency of these methods, especially the amplitude of instanton
effects, and of the network of exact solutions in supersymmetry. However, there
remain difficulties with the instanton computations at strong coupling.Comment: 17 pages, uses harvmac
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