6,419 research outputs found
Non-compact Mirror Bundles and (0,2) Liouville Theories
We study (0,2) deformations of N=2 Liouville field theory and its mirror
duality. A gauged linear sigma model construction of the ultraviolet theory
connects (0,2) deformations of Liouville field theory and (0,2) deformations of
N=2 SL(2,R)/U(1) coset model as a mirror duality. Our duality proposal from the
gauged linear sigma model completely agrees with the exact CFT analysis. In the
context of heterotic string compactifications, the deformation corresponds to
the introduction of a non-trivial gauge bundle. This non-compact
Landau-Ginzburg construction yields a novel way to study the gauge bundle
moduli for non-compact Calabi-Yau manifolds.Comment: 34 page
A Bilocal Field Theory in Four Dimensions
A bilocal field theory having M\"{o}bius gauge invariance is proposed. In
four dimensions there exists a zero momentum state of the first quantized
model, which belongs to a non-trivial BRS cohomology class. A field theory
lagrangian having a gauge invariance only in four dimensions is constructed.Comment: 13 pages, TEP-9R, LaTe
N=2 Liouville Theory with Boundary
We study N=2 Liouville theory with arbitrary central charge in the presence
of boundaries. After reviewing the theory on the sphere and deriving some
important structure constants, we investigate the boundary states of the theory
from two approaches, one using the modular transformation property of annulus
amplitudes and the other using the bootstrap of disc two-point functions
containing degenerate bulk operators. The boundary interactions describing the
boundary states are also proposed, based on which the precise correspondence
between boundary states and boundary interactions is obtained. The open string
spectrum between D-branes is studied from the modular bootstrap approach and
also from the reflection relation of boundary operators, providing a
consistency check for the proposal.Comment: 1+48 pages, no figure. typos corrected and references added. the
version to appear in JHE
D-brane Categories for Orientifolds -- The Landau-Ginzburg Case
We construct and classify categories of D-branes in orientifolds based on
Landau-Ginzburg models and their orbifolds. Consistency of the worldsheet
parity action on the matrix factorizations plays the key role. This provides
all the requisite data for an orientifold construction after embedding in
string theory. One of our main results is a computation of topological field
theory correlators on unoriented worldsheets, generalizing the formulas of Vafa
and Kapustin-Li for oriented worldsheets, as well as the extension of these
results to orbifolds. We also find a doubling of Knoerrer periodicity in the
orientifold context.Comment: 45 pages, 6 figure
Dual-camera system for high-speed imaging in particle image velocimetry
Particle image velocimetry is an important technique in experimental fluid
mechanics, for which it has been essential to use a specialized high-speed
camera. However, the high speed is at the expense of other performances of the
camera, i.e., sensitivity and image resolution. Here, we demonstrate that the
high-speed imaging is also possible with a pair of still cameras.Comment: 4 pages, accepted by Journal of Visualization (see
http://www.springerlink.com
Preliminary Results from Recent Measurements of the Antiprotonic Helium Hyperfine Structure
We report on preliminary results from a systematic study of the hyperfine
(HF) structure of antiprotonic helium. This precise measurement which was
commenced in 2006, has now been completed. Our initial analysis shows no
apparent density or power dependence and therefore the results can be averaged.
The statistical error of the observable M1 transitions is a factor of 60
smaller than that of three body quantum electrodynamic (QED) calculations,
while their difference has been resolved to a precision comparable to theory (a
factor of 10 better than our first measurement). This difference is sensitive
to the antiproton magnetic moment and agreement between theory and experiment
would lead to an increased precision of this parameter, thus providing a test
of CPT invariance.Comment: 6 pages, 4 figure
Superconformal Vortex Strings
We study the low-energy dynamics of semi-classical vortex strings living
above Argyres-Douglas superconformal field theories. The worldsheet theory of
the string is shown to be a deformation of the CP^N model which flows in the
infra-red to a superconformal minimal model. The scaling dimensions of chiral
primary operators are determined and the dimensions of the associated relevant
perturbations on the worldsheet and in the four dimensional bulk are found to
agree. The vortex string thereby provides a map between the A-series of N=2
superconformal theories in two and four dimensions.Comment: 22 pages. v2: change to introductio
The Stoyanovsky-Ribault-Teschner Map and String Scattering Amplitudes
Recently, Ribault and Teschner pointed out the existence of a one-to-one
correspondence between N-point correlation functions for the SL(2,C)_k/SU(2)
WZNW model on the sphere and certain set of 2N-2-point correlation functions in
Liouville field theory. This result is based on a seminal work by Stoyanovsky.
Here, we discuss the implications of this correspondence focusing on its
application to string theory on curved backgrounds. For instance, we analyze
how the divergences corresponding to worldsheet instantons in AdS_3 can be
understood as arising from the insertion of the dual screening operator in the
Liouville theory side. We also study the pole structure of N-point functions in
the 2D Euclidean black hole and its holographic meaning in terms of the Little
String Theory. This enables us to interpret the correspondence between CFTs as
encoding a LSZ-type reduction procedure. Furthermore, we discuss the scattering
amplitudes violating the winding number conservation in those backgrounds and
provide a formula connecting such amplitudes with observables in Liouville
field theory. Finally, we study the WZNW correlation functions in the limit k
-> 0 and show that, at the point k=0, the Stoyanovsky-Ribault-Teschner
dictionary turns out to be in agreement with the FZZ conjecture at a particular
point of the space of parameters where the Liouville central charge becomes
c=-2. This result makes contact with recent studies on the dynamical tachyon
condensation in closed string theory.Comment: 30 pages; no figure
NS5-Branes, T-Duality and Worldsheet Instantons
The equivalence of NS5-branes and ALF spaces under T-duality is well known.
However, a naive application of T-duality transforms the ALF space into a
smeared NS5-brane, de-localized on the dual, transverse, circle. In this paper
we re-examine this duality, starting from a two-dimensional N=(4,4) gauged
linear sigma model describing Taub-NUT space. After dualizing the circle fiber,
we find that the smeared NS5-brane target space metric receives corrections
from multi-worldsheet instantons. These instantons are identified as
Nielsen-Olesen vortices. We show that their effect is to break the isometry of
the target space, localizing the NS5-brane at a point. The contribution from
the k-instanton sector is shown to be proportional to the weighted integral of
the Euler form over the k-vortex moduli space. The duality also predicts the,
previously unknown, asymptotic exponential decay coefficient of the BPS vortex
solution.Comment: 26 pages. v2: Fourier modes of multi-vortex fermion zero mode
corrected. Reference added. v3: typo correcte
Hemoglobin genotype has minimal influence on the physiological response of juvenile atlantic cod (Gadus morhua) to environmental challenges
Hemoglobin (Hb) polymorphism in cod is associated with temperature‐related differences in biogeographical distribution, and several authors have suggested that functional characteristics of the various hemoglobin isoforms (HbIs) directly influence phenotypic traits such as growth rate. However, no study has directly examined whether Hb genotype translates into physiological differences at the whole animal level. Thus, we generated a family of juvenile Atlantic cod consisting of all three main Hb genotypes (HbI‐1/1, HbI‐2/2, and HbI‐1/2) by crossing a single pair of heterozygous parents, and we compared their metabolic and cortisol responses to an acute thermal challenge (10°C to their critical thermal maximum [CTM] or 22°C, respectively) and tolerance of graded hypoxia. There were no differences in routine metabolism (at 10°C), maximum metabolic rate, metabolic scope, CTM (overall mean 22.9° ± 0.2°C), or resting and poststress plasma cortisol levels among Hb genotypes. Further, although the HbI‐1/1 fish grew more (by 15%–30% during the first 9 mo) when reared at 10° ± 1°C and had a slightly enhanced hypoxia tolerance at 10°C (e.g., the critical O2 levels for HbI‐1/1, HbI‐2/2, and HbI‐1/2 cod were 35.56% ± 1.24%, and 40.20% ± 1.99% air saturation, respectively), these results are contradictory to expectations based on HbI functional properties. Thus, our findings (1) do not support previous assumptions that growth rate differences among cod Hb genotypes result from a more efficient use of the oxygen supply—that is, reduced standard metabolic rates and/or increased metabolic capacity—and (2) suggest that in juvenile cod, there is no selective advantage to having a particular Hb genotype with regards to the capacity to withstand ecologically relevant environmental challenges.<br /
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