207 research outputs found
Basic Twist Quantization of osp(1|2) and kappa-- Deformation of D=1 Superconformal Mechanics
The twisting function describing a nonstandard (super-Jordanian) quantum
deformation of is given in explicite closed form. The quantum
coproducts and universal R-matrix are presented. The non-uniqueness of the
twisting function as well as two real forms of the deformed
superalgebras are considered. One real quantum superalgebra is
interpreted as describing the -deformation of D=1, N=1 superconformal
algebra, which can be applied as a symmetry algebra of N=1 superconformal
mechanics.Comment: 13 pages,LaTeX, v2. References added, typos correcte
Drinfeld-Twisted Supersymmetry and Non-Anticommutative Superspace
We extend the analysis of hep-th/0408069 on a Lorentz invariant
interpretation of noncommutative spacetime to field theories on
non-anticommutative superspace with half the supersymmetries broken. By
defining a Drinfeld-twisted Hopf superalgebra, it is shown that one can restore
twisted supersymmetry and therefore obtain a twisted version of the chiral
rings along with certain Ward-Takahashi identities. Moreover, we argue that the
representation content of theories on the deformed superspace is identical to
that of their undeformed cousins and comment on the consequences of our
analysis concerning non-renormalization theorems.Comment: 1+17 pages; typos fixed, minor correction
Distance Functions and Normalization Under Stream Scenarios
Data normalization is an essential task when modeling a classification
system. When dealing with data streams, data normalization becomes especially
challenging since we may not know in advance the properties of the features,
such as their minimum/maximum values, and these properties may change over
time. We compare the accuracies generated by eight well-known distance
functions in data streams without normalization, normalized considering the
statistics of the first batch of data received, and considering the previous
batch received. We argue that experimental protocols for streams that consider
the full stream as normalized are unrealistic and can lead to biased and poor
results. Our results indicate that using the original data stream without
applying normalization, and the Canberra distance, can be a good combination
when no information about the data stream is known beforehand.Comment: Paper accepted to the 2023 International Joint Conference on Neural
Network
U(N) Instantons on N=1/2 superspace -- exact solution & geometry of moduli space
We construct the exact solution of one (anti)instanton in N=1/2 super
Yang-Mills theory defined on non(anti)commutative superspace. We first identify
N = 1/2 superconformal invariance as maximal spacetime symmetry. For gauge
group U(2), SU(2) part of the solution is given by the standard
(anti)instanton, but U(1) field strength also turns out nonzero. The solution
is SO(4) rotationally symmetric. For gauge group U(N), in contrast to the U(2)
case, we show that the entire U(N) part of the solution is deformed by
non(anti)commutativity and fermion zero-modes. The solution is no longer
rotationally symmetric; it is polarized into an axially symmetric configuration
because of the underlying non(anti)commutativity. We compute the `information
metric' of one (anti) instanton. We find that moduli space geometry is deformed
from hyperbolic space (Euclidean anti-de Sitter space) in a way anticipated
from reduced spacetime symmetry. Remarkably, the volume measure of the moduli
space turns out to be independent of the non(anti)commutativity. Implications
to D-branes in Ramond- Ramond flux background and Maldacena's gauge-gravity
correspondence are discussed.Comment: 39 pages, 3 figures, JHEP style; v2. typos corrected + a paragraph
adde
Manifest SO(N) invariance and S-matrices of three-dimensional N=2,4,8 SYM
An on-shell formalism for the computation of S-matrices of SYM theories in
three spacetime dimensions is presented. The framework is a generalization of
the spinor-helicity formalism in four dimensions. The formalism is applied to
establish the manifest SO(N) covariance of the on-shell superalgebra relevant
to N =2,4 and 8 SYM theories in d=3. The results are then used to argue for the
SO(N) invariance of the S-matrices of these theories: a claim which is proved
explicitly for the four-particle scattering amplitudes. Recursion relations
relating tree amplitudes of three-dimensional SYM theories are shown to follow
from their four-dimensional counterparts. The results for the four-particle
amplitudes are verified by tree-level perturbative computations and a unitarity
based construction of the integrand corresponding to the leading perturbative
correction is also presented for the N=8 theory. For N=8 SYM, the manifest
SO(8) symmetry is used to develop a map between the color-ordered amplitudes of
the SYM and superconformal Chern-Simons theories, providing a direct connection
between on-shell observables of D2 and M2-brane theories.Comment: 28 page
Gauge Theory on Noncommutative Supersphere from Supermatrix Model
We construct a supermatrix model which has a classical solution representing
the noncommutative (fuzzy) two-supersphere. Expanding supermatrices around the
classical background, we obtain a gauge theory on a noncommutative superspace
on sphere. This theory has supersymmetry and gauge
symmetry. We also discuss a commutative limit of the model keeping radius of
the supersphere fixed.Comment: 16 pages, Latex, typos corrected, references adde
N=1/2 quiver gauge theories from open strings with R-R fluxes
We consider a four dimensional N=1 gauge theory with bifundamental matter and
a superpotential, defined on stacks of fractional branes. By turning on a flux
for the R-R graviphoton field strength and computing open string amplitudes
with insertions of R-R closed string vertices, we introduce a
non-anticommutative deformation and obtain the N=1/2 version of the theory. We
also comment on the appearance of a new structure in the effective Lagrangian.Comment: 30 pages, 5 figures, JHEP class (included); some comments and a
reference adde
What we don't know about time
String theory has transformed our understanding of geometry, topology and
spacetime. Thus, for this special issue of Foundations of Physics commemorating
"Forty Years of String Theory", it seems appropriate to step back and ask what
we do not understand. As I will discuss, time remains the least understood
concept in physical theory. While we have made significant progress in
understanding space, our understanding of time has not progressed much beyond
the level of a century ago when Einstein introduced the idea of space-time as a
combined entity. Thus, I will raise a series of open questions about time, and
will review some of the progress that has been made as a roadmap for the
future.Comment: 15 pages; Essay for a special issue of Foundations of Physics
commemorating "Forty years of string theory
Three particle superstring amplitudes with massive legs
On-shell superspaces and associated spinor helicity techniques give an
efficient formulation of the Ward identities of on-shell supersymmetry for
scattering amplitudes and supply tools to construct their solutions. Based on
these techniques in this paper the general solutions of the Ward identities are
presented for three particle scattering amplitudes with one, two or three
massive legs for simple supersymmetry in ten and eight dimensions. It is shown
in examples how these solutions may be used to obtain concrete amplitudes for
the closed (IIB) and open superstring in a flat background. Explicit results
include all three point amplitudes with one massive leg whose functional form
is shown to be dictated completely by super-Poincare symmetry. The resulting
surprisingly simple series only involves massive superfields labelled by
completely symmetric little group representations. The extension to more
general explicit three and higher point amplitudes in string theory is
initiated. In appendices the field content of the fundamental massive
superfields of the open and closed superstring are listed in terms of the
Dynkin labels of a variety of groups which may be of independent interest.Comment: 45 pages. v2: typos corrected, references adde
Foraging habitat selection by gullâbilled tern (Gelochelidon nilotica) in Central Spain (CastillaâLa Mancha)
The gullâbilled tern breeds in temporary lakes in CastillaâLa Mancha in Central Spain but depends on surrounding land habitats to feed its chicks. It is therefore vital to know the type of environments it selects to capture prey to feed nestlings. The aim of this study was to evaluate the use of habitats for hunting by adult gullâbilled tern. Of 66 lakes monitored between 1996 and 2016, we found the gullâbilled tern used 12 for breeding. Each lake was used during this period for 1â14 breeding seasons. We selected circular areas around the three wetlands where the species bred in 2013 and 2014. Within these circles, we sampled a total of 60 random points and recorded 125 gullâbilled tern contacts (including between 1 and 39 birds). We estimated the same environmental variables at contact and random points, including land use and the distance to the nearest wetland, the nearest colony and to several types of anthropic uses (paved roads, houses, and cities). To evaluate habitat selection we calculated the Manly selection index for soil use variables, and fitted linear mixed models to evaluate differences in the distance variables. Land uses selected for foraging by the gullâbilled tern were mainly cereal crops, whereas vineyards were avoided. The birds foraged on average up to 2 km from the colonies and tended to avoid proximity of towns and paved roads, suggesting that the species is sensitive to human disturbance. Vineyards are the main land use in this region and the intensity is increasing. Our results suggest vineyards should be limited in areas around these wetlands so that gullâbilled terns may forage in their preferred sites
- âŠ