13,287 research outputs found
On Nonperturbative Exactness of Konishi Anomaly and the Dijkgraaf-Vafa Conjecture
In this paper we study the nonperturbative corrections to the generalized
Konishi anomaly that come from the strong coupling dynamics of the gauge
theory. We consider U(N) gauge theory with adjoint and Sp(N) or SO(N) gauge
theory with symmetric or antisymmetric tensor. We study the algebra of chiral
rotations of the matter field and show that it does not receive nonperturbative
corrections. The algebra implies Wess-Zumino consistency conditions for the
generalized Konishi anomaly which are used to show that the anomaly does not
receive nonperturbative corrections for superpotentials of degree less than
2l+1 where 2l=3c(Adj)-c(R) is the one-loop beta function coefficient. The
superpotentials of higher degree can be nonperturbatively renormalized because
of the ambiguities in the UV completion of the gauge theory. We discuss the
implications for the Dijkgraaf-Vafa conjecture.Comment: 23 page
On the hydrogen neutral outflowing disks of B[e] supergiants
(abridged) B[e] supergiants are known to possess geometrically thick dusty
disks. Disk-forming wind models have, however, been found to be insufficient in
reproducing the observed dust emission. This problem arises due to the severe
assumption that, as for classical Be stars, the near-infrared excess emission
originates in the disk. Modeling of the free-free and free-bound emission
therefore results in an upper limit for the disk mass loss rate, hampering dust
condensation in the disk. We propose a revised scenario for the non-spherical
winds of B[e] supergiants: a normal B-type line-driven polar wind and an
outflowing disk-forming wind that is neutral in hydrogen at, or very close to
the stellar surface. We concentrate on the pole-on seen LMC B[e] supergiant
R126 and calculate the line luminosities of the optical [OI] emission lines
with an outflowing disk scenario. In addition, we compute the free-free and
free-bound emission from a line-driven polar wind and model the spectral energy
distribution in the optical and near-infrared. Good fits to the [OI] line
luminosities are achieved for an outflowing disk that is neutral in hydrogen
right from the stellar surface. Neutral thereby means that hydrogen is ionized
by less than 0.1%. Consequently, the free-free and free-bound emission cannot
(dominantly) arise from the disk and cannot limit the disk mass loss rate. The
hydrogen neutral outflowing disk scenario therefore provides an ideal
environment for efficient dust formation. The spectral energy distribution in
the optical and near-infrared range can be well fitted with the stellar
continuum plus free-free and free-bound emission from the polar line-driven
wind. Our modeling further delivers minimum values for \dot{M}(disk) > 2.5d-5
M_sun/yr and for the density contrast between equatorial and polar wind of ~10.Comment: 9 pages, 8 figures, accepted for publication in A&
Improved quantum metrology using quantum error-correction
We consider quantum metrology in noisy environments, where the effect of
noise and decoherence limits the achievable gain in precision by quantum
entanglement. We show that by using tools from quantum error-correction this
limitation can be overcome. This is demonstrated in two scenarios, including a
many-body Hamiltonian with single-qubit dephasing or depolarizing noise, and a
single-body Hamiltonian with transversal noise. In both cases we show that
Heisenberg scaling, and hence a quadratic improvement over the classical case,
can be retained. Moreover, for the case of frequency estimation we find that
the inclusion of error-correction allows, in certain instances, for a finite
optimal interrogation time even in the asymptotic limit.Comment: Version 2 is the published version. Appendices contain Supplemental
materia
Dual Interpretations of Seiberg-Witten and Dijkgraaf-Vafa curves
We give dual interpretations of Seiberg-Witten and Dijkgraaf-Vafa (or matrix
model) curves in n=1 supersymmetric U(N) gauge theory. This duality
interchanges the rank of the gauge group with the degree of the superpotential;
moreover, the constraint of having at most log-normalizable deformations of the
geometry is mapped to a constraint in the number of flavors N_f < N in the dual
theory.Comment: Latex2e, 22 pages, 2 figure
A new unisexual salamander from Ohio
http://deepblue.lib.umich.edu/bitstream/2027.42/57145/1/OP709.pd
A new observational tracer for high-density disc-like structures around B[e] supergiants
The disc formation mechanism of B[e] supergiants is one of the puzzling
phenomena in massive star evolution. Rapid stellar rotation seems to play an
important role for the non-spherically symmetric mass-loss leading to a
high-density disc or ring-like structure of neutral material around these
massive and luminous objects. The radial density and temperature structure as
well as the kinematics within this high-density material are, however, not well
studied. Based on high-resolution optical spectra of a sample of B[e]
supergiants in the Magellanic Clouds we especially searched for tracers of the
kinematics within their discs. Besides the well-known [O I] lines, we
discovered the [Ca II] {\lambda}{\lambda}7291, 7324 lines that can be used as a
complementary set of disc tracers. We find that these lines originate from very
high-density regions, located closer to the star than the [O I] {\lambda}5577
line-forming region. The line profiles of both the [O I] and the [Ca II] lines
indicate that the discs or rings of high-density material are in Keplerian
rotation. We estimate plausible ranges of disc inclination angles for the
sample of B[e] supergiants and suggest that the star LHA 120-S 22 might have a
spiral arm rather than a disc.Comment: 10 pages, 4 figures, 5 table
Two Wide Planetary-Mass Companions to Solar-Type Stars in Upper Scorpius
At wide separations, planetary-mass and brown dwarf companions to solar type
stars occupy a curious region of parameters space not obviously linked to
binary star formation or solar-system scale planet formation. These companions
provide insight into the extreme case of companion formation (either binary or
planetary), and due to their relative ease of observation when compared to
close companions, they offer a useful template for our expectations of more
typical planets. We present the results from an adaptive optics imaging survey
for wide (50-500 AU) companions to solar type stars in Upper Scorpius. We
report one new discovery of a ~14 M_J companion around GSC 06214-00210, and
confirm that the candidate planetary mass companion 1RXS J160929.1-210524
detected by Lafreniere et al (2008) is in fact co-moving with its primary star.
In our survey, these two detections correspond to ~4% of solar type stars
having companions in the 6-20 M_J mass and 200-500 AU separation range. This
figure is higher than would be expected if brown dwarfs and planetary mass
companions were drawn from an extrapolation of the binary mass function.
Finally, we discuss implications for the formation of these objects.Comment: 11 Pages, 7 Figures, Accepted for Ap
Two Wide Planetary-mass Companions to Solar-type Stars in Upper Scorpius
At wide separations, planetary-mass and brown dwarf companions to solar-type stars occupy a curious region of
parameter space not obviously linked to binary star formation or solar system scale planet formation. These
companions provide insight into the extreme case of companion formation (either binary or planetary), and
due to their relative ease of observation when compared to close companions, they offer a useful template
for our expectations of more typical planets. We present the results from an adaptive optics imaging survey
for wide (~50–500 AU) companions to solar-type stars in Upper Scorpius. We report one new discovery of a
~14 M_J companion around GSC 06214−00210and confirm that the candidate planetary-mass companion 1RXS
J160929.1−210524 detected by Lafrenière et al. is in fact comoving with its primary star. In our survey, these
two detections correspond to ~4% of solar-type stars having companions in the 6–20 M_J mass and ~200–500 AU
separation range. This figure is higher than would be expected if brown dwarfs and planetary-mass companions
were drawn from an extrapolation of the binary mass function. Finally, we discuss implications for the formation
of these objects
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