706 research outputs found
Matrix Holzer analyses for fully-coupled vibrations of clustered launch-vehicle configurations including applications to the Titan IIIC and uncoupled Saturn I cases
Matrix-Holzer analyses for predicting free vibration modes of clustered launch vehicle configurations including Titan IIIC and uncoupled Saturn I case
Constructive factorization of LPDO in two variables
We study conditions under which a partial differential operator of arbitrary
order in two variables or ordinary linear differential operator admits a
factorization with a first-order factor on the left. The factorization process
consists of solving, recursively, systems of linear equations, subject to
certain differential compatibility conditions. In the generic case of partial
differential operators one does not have to solve a differential equation. In
special degenerate cases, such as ordinary differential, the problem is finally
reduced to the solution of some Riccati equation(s). The conditions of
factorization are given explicitly for second- and, and an outline is given for
the higher-order case.Comment: 16 pages, to be published in Journal "Theor. Math. Phys." (2005
A note on the dual of N=1 super Yang-Mills theory
We refine the dictionary of the gauge/gravity correspondence realizing N=1
super Yang-Mills by means of D5-branes wrapped on a resolved Calabi-Yau space.
This is done by fixing an ambiguity on the correct interpretation of the
holographic dual of the running gauge coupling and amounts to identify a
specific 2-cycle in the dual ten-dimensional supergravity background. In doing
so, we also discuss the role played in this context by gauge transformations in
the relevant seven-dimensional gauged supergravity. While all nice properties
of the duality are maintained, this modification of the dictionary has some
interesting physical consequences and solves a puzzle recently raised in the
literature. In this refined framework, it is also straightforward to see how
the correspondence naturally realizes a geometric transition.Comment: 11 pages, latex; minor changes and typos correcte
Manifesting Unobtainable Secrets: Threshold Elliptic Curve Key Generation using Nested Shamir Secret Sharing
We present a mechanism to manifest unobtainable secrets using a nested Shamir
secret sharing scheme to create public/private key pairs for elliptic curves. A
threshold secret sharing scheme can be used as a decentralised trust mechanism
with applications in identity validation, message decryption, and agreement
empowerment. Decentralising trust means that there is no single point
vulnerability which could enable compromise of a system. Our primary interest
is in twisted Edwards curves as used in EdDSA, and the related Diffie-Hellman
key-exchange algorithms. The key generation is also decentralised, so can be
used as a decentralised secret RNG suitable for use in other algorithms. The
algorithms presented could be used to fill a ``[TBS]'' in the draft IETF
specification ``Threshold modes in elliptic curves'' published in 2020 and
updated in 2022
Deforming baryons into confining strings
We find explicit probe D3-brane solutions in the infrared of the
Maldacena-Nunez background. The solutions describe deformed baryon vertices: q
external quarks are separated in spacetime from the remaining N-q. As the
separation is taken to infinity we recover known solutions describing infinite
confining strings in gauge theory. We present results for the
mass of finite confining strings as a function of length. We also find probe
D2-brane solutions in a confining type IIA geometry, the reduction of a G_2
holonomy M theory background. The relation between these deformed baryons and
confining strings is not as straightforward.Comment: 1+13 pages. LaTeX. 3 Figures. Factor of 2N fixed to N for the IIA
background. Minor changes to tex
A Gravity Dual of the Chiral Anomaly
We study effects associated with the chiral anomaly for a cascading
gauge theory using gauge/gravity duality. In the gravity
dual the anomaly is a classical feature of the supergravity solution, and the
breaking of the U(1) R-symmetry down to proceeds via the Higgs
mechanism.Comment: 15 pages, derivation of vector mass corrected, main conclusions
unchanged, a sign convention changed in section
Rotating and Orbiting Strings in the Near-Horizon Brane Backgrounds
Using the Schwarzschild-type coordinates in stead of the global ones we
reconstruct the classical rotating closed string solutions in the AdS*5 x S*5
backgrounds. They are explicitly described by the Jacobi elliptic and
trigonometrical functions of worldsheet coordinates. We study the orbiting
closed string configurations in the near-horizon geometries of Dp, NS1 and NS5
branes, and derive the energy and spin of them, whose relation takes a simple
form for short strings. Specially in the D5 and NS5 backgrounds we have a
linear relation that the energy of the point-like string is proportional to the
spin, which is associated with the spectrum of strings in the pp-wave
geometries obtained by taking a special Penrose limit on the D5 and NS5
backgrounds.Comment: 15 pages, LaTeX, no figure
Suppression-induced forgetting:a pre-registered replication of the think/no-think paradigm
Post-traumatic stress disorder is characterised by recurring memories of a traumatic experience despite deliberate attempts to forget (i.e., suppression). The Think/No-Think (TNT) task has been used widely in the laboratory to study suppression-induced forgetting. During the task, participants learn a series of cue-target word pairs. Subsequently, they are presented with a subset of the cue words and are instructed to think (respond items) or not think about the corresponding target (suppression items). Baseline items are not shown during this phase. Successful suppression-induced forgetting is indicated by the reduced recall of suppression compared to baseline items in recall tests using either the same or different cues than originally studied (i.e., same- and independent-probe tests, respectively). The current replication was a pre-registered collaborative effort to evaluate an online experimenter-present version of the paradigm in 150 English-speaking healthy individuals (89 females; MAge = 31.14, SDAge = 7.73). Overall, we did not replicate the suppression-induced forgetting effect (same-probe: BF01 = 7.84; d = 0.03 [95% CI: −0.13; 0.20]; independent-probe: BF01 = 5.71; d = 0.06 [95% CI: −0.12; 0.24]). These null results should be considered in light of our online implementation of the paradigm. Nevertheless, our findings call into question the robustness of suppression-induced forgetting
Stable Non-Supersymmetric Supergravity Solutions from Deformations of the Maldacena-Nunez Background
We study a deformation of the type IIB Maldacena-Nunez background which
arises as the near-horizon limit of NS5 branes wrapped on a two-cycle. This
background is dual to a "little string theory" compactified on a two-sphere, a
theory which at low energies includes four-dimensional N = 1 super Yang-Mills
theory. The deformation we study corresponds to a mass term for some of the
scalar fields in this theory, and it breaks supersymmetry completely. In the
language of seven-dimensional SO(4) gauged supergravity the deformation
involves (at leading order) giving a VEV, depending only on the radial
coordinate, to a particular scalar field. We explicitly construct the
corresponding solution at leading order in the deformation, both in
seven-dimensional and in ten-dimensional supergravity, and we verify that it
completely breaks supersymmetry. Since the original background had a mass gap
and we are performing a small deformation, the deformed background is
guaranteed to be stable even though it is not supersymmetric.Comment: 1+31 pages, one figure. v2: minor clarifications, refs adde
Non-perturbative gauge superpotentials from supergravity
We study U(N) SQCD with N_f <= N flavors of quarks and antiquarks by
engineering it with a configuration of fractional D3-branes on a C^3 / Z_2 x
Z_2 orbifold. In particular we show how the moduli space of the gauge theory
naturally emerges from the classical geometry produced by the D3-branes, and
how the non-perturbatively generated superpotential is recovered from
geometrical data.Comment: LaTeX, 18 pages, 4 figures; v2: published version with minor changes
and an added referenc
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