3,407 research outputs found
Operator Counting and Eigenvalue Distributions for 3D Supersymmetric Gauge Theories
We give further support for our conjecture relating eigenvalue distributions
of the Kapustin-Willett-Yaakov matrix model in the large N limit to numbers of
operators in the chiral ring of the corresponding supersymmetric
three-dimensional gauge theory. We show that the relation holds for
non-critical R-charges and for examples with {\mathcal N}=2 instead of
{\mathcal N}=3 supersymmetry where the bifundamental matter fields are
nonchiral. We prove that, for non-critical R-charges, the conjecture is
equivalent to a relation between the free energy of the gauge theory on a three
sphere and the volume of a Sasaki manifold that is part of the moduli space of
the gauge theory. We also investigate the consequences of our conjecture for
chiral theories where the matrix model is not well understood.Comment: 27 pages + appendices, 5 figure
Lethal Mutagenesis of Poliovirus Mediated by a Mutagenic Pyrimidine Analogue
Lethal mutagenesis is the mechanism of action of ribavirin against poliovirus (PV) and numerous other RNA viruses. However, there is still considerable debate regarding the mechanism of action of ribavirin against a variety of RNA viruses. Here we show by using T7 RNA polymerase mediated production of PV genomic RNA, PV polymerase-catalyzed primer extension and cell-free PV synthesis that a pyrimidine ribonucleoside triphosphate analogue (rPTP) with ambiguous basepairing capacity is an efficient mutagen of the PV genome. The in vitro incorporation properties of rPTP are superior to ribavirin triphosphate. We observed a log-linear relationship between virus titer reduction and the number of rPMP molecules incorporated. A PV genome encoding a high-fidelity polymerase was more sensitive to rPMP incorporation, consistent with diminished mutational robustness of high-fidelity PV. The nucleoside (rP) did not exhibit antiviral activity in cell culture owing to the inability of rP to be converted to rPMP by cellular nucleotide kinases. rP was also a poor substrate for herpes simplex virus thymidine kinase. The block to nucleoside phosphorylation could be bypassed by treatment with the P nucleobase, which exhibited both antiviral activity and mutagenesis, presumably a reflection of rP nucleotide formation by a nucleotide salvage pathway. These studies provide additional support for lethal mutagenesis as an antiviral strategy, suggest that rPMP prodrugs may be highly efficacious antiviral agents, and provide a new tool to determine the sensitivity of RNA virus genomes to mutagenesis as well as interrogation of the impact of mutational load on the population dynamics of these viruses
Production of eta Mesons in Double Pomeron Exchange
We estimate the production cross sections for and mesons
via pomeron-pomeron fusion in peripheral heavy-ion collisions. Total and
elastic PP cross sections are calculated in an equivalent pomeron
approximation.Comment: 9 pages, 3 Postscript figure
The Kaon -parameter with Wilson Fermions
We calculate the kaon -parameter in quenched lattice QCD at
using Wilson fermions at and . We use two kinds of
non-local (``smeared'') sources for quark propagators to calculate the matrix
elements between states of definite momentum. The use of smeared sources yields
results with much smaller errors than obtained in previous calculations with
Wilson fermions. By combining results for and , we show that one can carry out the non-perturbative subtraction
necessary to remove the dominant lattice artifacts induced by the chiral
symmetry breaking term in the Wilson action. Our final results are in good
agreement with those obtained using staggered fermions. We also present results
for -parameters of the part of the electromagnetic penguin
operators, and preliminary results for \bk\ in the presence of two flavors of
dynamical quarks.Comment: 39 pages, including 9 PS figures (LA UR-91-3522
Direct Mediation and Metastable Supersymmetry Breaking for SO(10)
We examine a metastable Macroscopic SO(N) SQCD model of
Intriligator, Seiberg and Shih (ISS). We introduce various baryon and meson
deformations, including multitrace operators and explore embedding an SO(10)
parent of the standard model into two weakly gauged flavour sectors. Direct
fundamental messengers and the symmetric pseudo-modulus messenger mediate SUSY
breaking to the MSSM. Gaugino and sfermion masses are computed and compared for
each deformation type. We also explore reducing the rank of the magnetic quark
matrix of the ISS model and find an additional fundamental messenger.Comment: 43 pages, Latex. Version to appear in JHEP
Supersymmetric Field-Theoretic Models on a Supermanifold
We propose the extension of some structural aspects that have successfully
been applied in the development of the theory of quantum fields propagating on
a general spacetime manifold so as to include superfield models on a
supermanifold. We only deal with the limited class of supermanifolds which
admit the existence of a smooth body manifold structure. Our considerations are
based on the Catenacci-Reina-Teofillatto-Bryant approach to supermanifolds. In
particular, we show that the class of supermanifolds constructed by
Bonora-Pasti-Tonin satisfies the criterions which guarantee that a
supermanifold admits a Hausdorff body manifold. This construction is the
closest to the physicist's intuitive view of superspace as a manifold with some
anticommuting coordinates, where the odd sector is topologically trivial. The
paper also contains a new construction of superdistributions and useful results
on the wavefront set of such objects. Moreover, a generalization of the
spectral condition is formulated using the notion of the wavefront set of
superdistributions, which is equivalent to the requirement that all of the
component fields satisfy, on the body manifold, a microlocal spectral condition
proposed by Brunetti-Fredenhagen-K\"ohler.Comment: Final version to appear in J.Math.Phy
Ultracompact HII regions with extended emission: The complete view
\ua9 2019 The Author(s). In this paper, we present the results of a morphological study performed on a sample of 28 ultracompact HII (UC HII) regions located near extended free-free emission, using radio continuum (RC) observations at 3.6 cm with the C and D Very Large Array (VLA) configurations, with the aim of determining a direct connection between them. By using previously published observations in B and D VLA configurations, we compiled a final catalogue of 21 UC HII regions directly connected with the surrounding extended emission (EE). The observed morphology of most of the UC HII regions in RC emission is irregular (single- or multipeaked sources) and resembles a classical bubble structure in the Galactic plane with well-defined cometary arcs. RC images superimposed on colour composite Spitzer images reinforce the assignations of direct connection by the spatial coincidence between the UC components and regions of saturated 24 μm emission. We also find that the presence of EE may be crucial to understand the observed infrared excess because an underestimation of ionizing Lyman photons was considered in previous works (e.g. Wood & Churchwell; Kurtz, Churchwell & Wood)
The first GCT camera for the Cherenkov Telescope Array
The Gamma Cherenkov Telescope (GCT) is proposed to be part of the Small Size
Telescope (SST) array of the Cherenkov Telescope Array (CTA). The GCT
dual-mirror optical design allows the use of a compact camera of diameter
roughly 0.4 m. The curved focal plane is equipped with 2048 pixels of
~0.2{\deg} angular size, resulting in a field of view of ~9{\deg}. The GCT
camera is designed to record the flashes of Cherenkov light from
electromagnetic cascades, which last only a few tens of nanoseconds. Modules
based on custom ASICs provide the required fast electronics, facilitating
sampling and digitisation as well as first level of triggering. The first GCT
camera prototype is currently being commissioned in the UK. On-telescope tests
are planned later this year. Here we give a detailed description of the camera
prototype and present recent progress with testing and commissioning.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherlands. All CTA contributions at
arXiv:1508.0589
Towards the F-Theorem: N=2 Field Theories on the Three-Sphere
For 3-dimensional field theories with {\cal N}=2 supersymmetry the Euclidean
path integrals on the three-sphere can be calculated using the method of
localization; they reduce to certain matrix integrals that depend on the
R-charges of the matter fields. We solve a number of such large N matrix models
and calculate the free energy F as a function of the trial R-charges consistent
with the marginality of the superpotential. In all our {\cal N}=2
superconformal examples, the local maximization of F yields answers that scale
as N^{3/2} and agree with the dual M-theory backgrounds AdS_4 x Y, where Y are
7-dimensional Sasaki-Einstein spaces. We also find in toric examples that local
F-maximization is equivalent to the minimization of the volume of Y over the
space of Sasakian metrics, a procedure also referred to as Z-minimization.
Moreover, we find that the functions F and Z are related for any trial
R-charges. In the models we study F is positive and decreases along RG flows.
We therefore propose the "F-theorem" that we hope applies to all 3-d field
theories: the finite part of the free energy on the three-sphere decreases
along RG trajectories and is stationary at RG fixed points. We also show that
in an infinite class of Chern-Simons-matter gauge theories where the
Chern-Simons levels do not sum to zero, the free energy grows as N^{5/3} at
large N. This non-trivial scaling matches that of the free energy of the
gravity duals in type IIA string theory with Romans mass.Comment: 66 pages, 10 figures; v2: refs. added, minor improvement
From Necklace Quivers to the F-theorem, Operator Counting, and T(U(N))
The matrix model of Kapustin, Willett, and Yaakov is a powerful tool for
exploring the properties of strongly interacting superconformal Chern-Simons
theories in 2+1 dimensions. In this paper, we use this matrix model to study
necklace quiver gauge theories with {\cal N}=3 supersymmetry and U(N)^d gauge
groups in the limit of large N. In its simplest application, the matrix model
computes the free energy of the gauge theory on S^3. The conjectured F-theorem
states that this quantity should decrease under renormalization group flow. We
show that for a simple class of such flows, the F-theorem holds for our
necklace theories. We also provide a relationship between matrix model
eigenvalue distributions and numbers of chiral operators that we conjecture
holds more generally. Through the AdS/CFT correspondence, there is therefore a
natural dual geometric interpretation of the matrix model saddle point in terms
of volumes of 7-d tri-Sasaki Einstein spaces and some of their 5-d
submanifolds. As a final bonus, our analysis gives us the partition function of
the T(U(N)) theory on S^3.Comment: 3 figures, 41 pages; v2 minor improvements, refs adde
- …