1,473 research outputs found
From 3d duality to 2d duality
In this paper we discuss supersymmetric gauge theories and
their IR dualities when they are compactified on a circle of radius , and
when we take the limit in which . The limit depends on how
the mass parameters are scaled as , and often vacua become infinitely
distant in the limit, leading to a direct sum of different theories.
For generic mass parameters, when we take the same limit on both sides of a
duality, we obtain dualities (between gauge theories and/or
Landau-Ginzburg theories) that pass all the usual tests. However, when there
are non-compact branches the discussion is subtle because the metric on the
moduli space, which is not controlled by supersymmetry, plays an important role
in the low-energy dynamics after compactification. Generally speaking, for IR
dualities of gauge theories, we conjecture that dualities involving non-compact
Higgs branches survive. On the other hand when there is a non-compact Coulomb
branch on at least one side of the duality, the duality fails already when the
theories are compactified on a circle. Using the valid reductions we
reproduce many known IR dualities, giving further evidence for their
validity, and we also find new dualities
3d dualities from 4d dualities
Many examples of low-energy dualities have been found in supersymmetric gauge
theories with four supercharges, both in four and in three space-time
dimensions. In these dualities, two theories that are different at high
energies have the same low-energy limit. In this paper we clarify the relation
between the dualities in four and in three dimensions. We show that every four
dimensional duality gives rise to a three dimensional duality between theories
that are similar, but not identical, to the dimensional reductions of the four
dimensional dual gauge theories to three dimensions. From these specific three
dimensional dualities one can flow to many other low-energy dualities,
including known three dimensional dualities and many new ones. We discuss in
detail the case of three dimensional SU(N_c) supersymmetric QCD theories,
showing how to derive new duals for these theories from the four dimensional
duality.Comment: 84 pages, 3 figures, harvmac. v2: added an appendix on the reduction
of the 4d index to the 3d partition function, added references, minor
corrections and change
Lack of static lattice distortion in
We investigated the possibility of temperature dependent lattice distortions
in the pyrochlore compound TbTiO by measuring the internal
magnetic field distribution, using muon spin resonance, and comparing it to the
susceptibility. The measurements are done at temperatures as low as 70 mK and
external fields up to 6 kG. We find that the evolution of the width of the
field distribution can be explained by spin susceptibility only, thus ruling
out a temperature dependent hyperfine coupling. We conclude that lattice
deformations are absent in TbTiO.Comment: 8 pages, 5 figures, accepted for publication in J. Phys. Condens.
Matter. (Proceedings of Highly Frustrated Magnetism 2006); Corrections of
various typo
On the Composition of Gauge Structures
A formulation for a non-trivial composition of two classical gauge structures
is given: Two parent gauge structures of a common base space are synthesized so
as to obtain a daughter structure which is fundamental by itself. The model is
based on a pair of related connections that take their values in the product
space of the corresponding Lie algebras. The curvature, the covariant exterior
derivatives and the associated structural identities, all get contributions
from both gauge groups. The various induced structures are classified into
those whose composition is given just by trivial means, and those which possess
an irreducible nature. The pure irreducible piece, in particular, generates a
complete super-space of ghosts with an attendant set of super-BRST variation
laws, both of which are purely of a geometrical origin.Comment: Few elaborations are added to section 4 and section 5. To be
published in Journal of Physics A: Mathematical and General. 21 page
3d dualities from 4d dualities for orthogonal groups
We extend recent work on the relation of 4d and 3d IR dualities of
supersymmetric gauge theories with four supercharges to the case of orthogonal
gauge groups. The distinction between different SO(N) gauge theories in 4d
plays an important role in this relation. We show that the 4d duality leads to
a 3d duality between an SO(N_c) gauge theory with N_f flavors and an
SO(N_f-N_c+2) theory with N_f flavors and extra singlets, and we derive its
generalization in the presence of Chern-Simons terms. There are two different
O(N) theories in 3d, which we denote by O(N)_\pm, and we also show that the
O(N_c)_- gauge theory is dual to a Spin(N_f-N_c+2) theory, and derive from 4d
the known duality between O(N_c)_+ and O(N_f-N_c+2)_+. We verify the
consistency of these 3d dualities by various methods, including index
computations.Comment: 49 pages, harvmac. v2: a minor chang
The 2dF gravitational lens survey
The 2 degree Field (2dF) galaxy redshift survey will involve obtaining
approximately 2.5 x 10^5 spectra of objects previously identified as galaxy
candidates on morphological grounds. Included in these spectra should be about
ten gravitationally-lensed quasars, all with low-redshift galaxies as
deflectors (as the more common lenses with high-redshift deflectors will be
rejected from the survey as multiple point-sources). The lenses will appear as
superpositions of galaxy and quasar spectra, and both cross-correlation
techniques and principal components analysis should be able to identify
candidates systematically. With the 2dF survey approximately half-completed it
is now viable to begin a systematic search for these spectroscopic lenses, and
the first steps of this project are described here.Comment: PASA (OzLens edition), in press; 4 pages, 0 figure
WISeREP - An Interactive Supernova Data Repository
We have entered an era of massive data sets in astronomy. In particular, the
number of supernova (SN) discoveries and classifications has substantially
increased over the years from few tens to thousands per year. It is no longer
the case that observations of a few prototypical events encapsulate most
spectroscopic information about SNe, motivating the development of modern tools
to collect, archive, organize and distribute spectra in general, and SN spectra
in particular. For this reason we have developed the Weizmann Interactive
Supernova data REPository - WISeREP - an SQL-based database (DB) with an
interactive web-based graphical interface. The system serves as an archive of
high quality SN spectra, including both historical (legacy) data as well as
data that is accumulated by ongoing modern programs. The archive provides
information about objects, their spectra, and related meta-data. Utilizing
interactive plots, we provide a graphical interface to visualize data, perform
line identification of the major relevant species, determine object redshifts,
classify SNe and measure expansion velocities. Guest users may view and
download spectra or other data that have been placed in the public domain.
Registered users may also view and download data that are proprietary to
specific programs with which they are associated. The DB currently holds >8000
spectra, of which >5000 are public; the latter include published spectra from
the Palomar Transient Factory, all of the SUSPECT archive, the
Caltech-Core-Collapse Program, the CfA SN spectra archive and published spectra
from the UC Berkeley SNDB repository. It offers an efficient and convenient way
to archive data and share it with colleagues, and we expect that data stored in
this way will be easy to access, increasing its visibility, usefulness and
scientific impact.Comment: To be published in PASP. WISeREP:
http://www.weizmann.ac.il/astrophysics/wiserep
Nutation versus angular dependent NQR spectroscopy and the impact of underdoping on charge inhomogeneities in YBaCuO
We describe two different nuclear quadrupole resonance (NQR) based
techniques, designed to measure the local asymmetry of the internal electric
field gradient, and the tilt angle of the main NQR principal axis z from the
crystallographic axis c. These techniques use the dependence of the NQR signal
on the duration of the radio frequency (rf) pulse and on the direction of the
rf field H1 with respect to the crystal axis. The techniques are applied to
oriented powder of YBaCuO fully enriched with 63Cu.
Measurements were performed at different frequencies, corresponding to
different in-plane copper sites with respect to the dopant. Combining the
results from both techniques, we conclude that oxygen deficiency in the chain
layer lead to a rotation of the NQR main principal axis at the nearby Cu on the
CuO2 planes by 20+-degrees. This occurs with no change to the asymmetry. The
axis rotation associated with oxygen deficiency means that there must be
electric field inhomogeneities in the CuO2 planes only in the vicinity of the
missing oxygen.Comment: 9 pages, 10 figure
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