84 research outputs found
The Omega Deformation, Branes, Integrability, and Liouville Theory
We reformulate the Omega-deformation of four-dimensional gauge theory in a
way that is valid away from fixed points of the associated group action. We use
this reformulation together with the theory of coisotropic A-branes to explain
recent results linking the Omega-deformation to integrable Hamiltonian systems
in one direction and Liouville theory of two-dimensional conformal field theory
in another direction.Comment: 96 p
Matrix Model Conjecture for Exact BS Periods and Nekrasov Functions
We give a concise summary of the impressive recent development unifying a
number of different fundamental subjects. The quiver Nekrasov functions
(generalized hypergeometric series) form a full basis for all conformal blocks
of the Virasoro algebra and are sufficient to provide the same for some
(special) conformal blocks of W-algebras. They can be described in terms of
Seiberg-Witten theory, with the SW differential given by the 1-point resolvent
in the DV phase of the quiver (discrete or conformal) matrix model
(\beta-ensemble), dS = ydz + O(\epsilon^2) = \sum_p \epsilon^{2p}
\rho_\beta^{(p|1)}(z), where \epsilon and \beta are related to the LNS
parameters \epsilon_1 and \epsilon_2. This provides explicit formulas for
conformal blocks in terms of analytically continued contour integrals and
resolves the old puzzle of the free-field description of generic conformal
blocks through the Dotsenko-Fateev integrals. Most important, this completes
the GKMMM description of SW theory in terms of integrability theory with the
help of exact BS integrals, and provides an extended manifestation of the basic
principle which states that the effective actions are the tau-functions of
integrable hierarchies.Comment: 14 page
The matrix model version of AGT conjecture and CIV-DV prepotential
Recently exact formulas were provided for partition function of conformal
(multi-Penner) beta-ensemble in the Dijkgraaf-Vafa phase, which, if interpreted
as Dotsenko-Fateev correlator of screenings and analytically continued in the
number of screening insertions, represents generic Virasoro conformal blocks.
Actually these formulas describe the lowest terms of the q_a-expansion, where
q_a parameterize the shape of the Penner potential, and are exact in the
filling numbers N_a. At the same time, the older theory of CIV-DV prepotential,
straightforwardly extended to arbitrary beta and to non-polynomial potentials,
provides an alternative expansion: in powers of N_a and exact in q_a. We check
that the two expansions coincide in the overlapping region, i.e. for the lowest
terms of expansions in both q_a and N_a. This coincidence is somewhat
non-trivial, since the two methods use different integration contours:
integrals in one case are of the B-function (Euler-Selberg) type, while in the
other case they are Gaussian integrals.Comment: 27 pages, 1 figur
On open-closed extension of boundary string field theory
We investigate a classical open-closed string field theory whose open string
sector is given by boundary string field theory. The open-closed interaction is
introduced by the overlap of a boundary state with a closed string field. With
the help of the Batalin-Vilkovisky formalism, the closed string sector is
determined to be the HIKKO closed string field theory. We also discuss the
gauge invariance of this theory in both open and closed string sides.Comment: 25 pages, 2 figures, comments and a reference added, typos correcte
Correlators of Wilson loops and local operators from multi-matrix models and strings in AdS
We study correlation functions of Wilson loops and local operators in a
subsector of N=4 SYM which preserves two supercharges. Localization arguments
allow to map the problem to a calculation in bosonic two-dimensional Yang-Mills
theory. In turn, this can be reduced to computing correlators in certain
Gaussian multi-matrix models. We focus on the correlation function of a Wilson
loop and two local operators, and solve the corresponding three-matrix model
exactly in the planar limit. We compare the strong coupling behavior to string
theory in AdS_5xS^5, finding precise agreement. We pay particular attention to
the case in which the local operators have large R-charge J \sim sqrt{lambda}
at strong coupling.Comment: 50 pages, 9 figures. v2: minor changes, references adde
String Theory on Warped AdS_3 and Virasoro Resonances
We investigate aspects of holographic duals to time-like warped AdS_3
space-times--which include G\"odel's universe--in string theory. Using
worldsheet techniques similar to those that have been applied to AdS_3
backgrounds, we are able to identify space-time symmetry algebras that act on
the dual boundary theory. In particular, we always find at least one Virasoro
algebra with computable central charge. Interestingly, there exists a dense set
of points in the moduli space of these models in which there is actually a
second commuting Virasoro algebra, typically with different central charge than
the first. We analyze the supersymmetry of the backgrounds, finding related
enhancements, and comment on possible interpretations of these results. We also
perform an asymptotic symmetry analysis at the level of supergravity, providing
additional support for the worldsheet analysis.Comment: 24 pages + appendice
Localization of the four-dimensional N=4 SYM to a two-sphere and 1/8 BPS Wilson loops
We localize the four-dimensional N=4 super Yang-Mills theory on a four-sphere
to the two-dimensional constrained Hitchin/Higgs-Yang-Mills (cHYM) theory on a
two-sphere S^2. We show that expectation values of certain 1/8 BPS
supersymmetric Wilson loops on S^2 in the 4d N=4 SYM is captured by the 2d cHYM
theory. We further argue that expectation values of Wilson loops in the cHYM
theory agree with the prescription "two-dimensional bosonic Yang-Mills
excluding instanton contributions". Hence, we support the recent conjecture by
Drukker, Giombi, Ricci and Trancanelli on the 1/8 BPS Wilson loops on S^2 in
the 4d N=4 SYM.Comment: 49 pages; v3: typos correcte
Modified Epidermal Growth Factor Receptor (EGFR)-Bearing Liposomes (MRBLs) Are Sensitive to EGF in Solution
Cancers often overexpress EGF and other growth factors to promote cell replication and migration. Previous work has not produced targeted drug carriers sensitive to abnormal amounts of growth factors. This work demonstrates that liposomes bearing EGF receptors covalently crosslinked to p-toluic acid or methyl-PEO4-NHS ester (or, in short, MRBLs) exhibit an increased rate of release of encapsulated drug compounds when EGF is present in solution. Furthermore, the modified EGF receptors retain the abilities to form dimers in the presence of EGF and bind specifically to EGF. These results demonstrate that MRBLs are sensitive to EGF in solution and indicate that MRBL-reconstituted modified EGF receptors, in the presence of EGF in solution, form dimers which increase MRBL permeability to encapsulated compounds
Effects of probiotics on the prevention of atopic dermatitis
Atopic dermatitis (AD) is an immune disorder that is becoming increasingly prevalent throughout the world. The exact etiology of AD remains unknown, and a cure for AD is not currently available. The hypothesis that appropriate early microbial stimulation contributes to the establishment of a balanced immune system in terms of T helper type Th1, Th2, and regulatory T cell (Treg) responses has led to the use of probiotics for the prevention and treatment of AD in light of various human clinical studies and animal experiments. Meta-analysis data suggests that probiotics can alleviate the symptoms of AD in infants. The effects of balancing Th1/Th2 immunity and enhancing Treg activity via the interaction of probiotics with dendritic cells have been described in vitro and in animal models, although such an effect has not been demonstrated in human studies. In this review, we present some highlights of the immunomodulatory effects of probiotics in humans and animal studies with regard to their effects on the prevention of AD
Defects, Decay, and Dissipated States
The worldsheet renormalization group approach to tachyon condensation in string theory is reviewed. The open string case is summarized with examples, and closed string tachyon condensation on nonsupersymmetric orbifolds is examined in detail. The idea that the renormalization group dissipates the localized states associated to the defect is explored
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