3,048 research outputs found
Unconventional Supersymmetry at the Boundary of AdS_4 Supergravity
In this paper we perform, in the spirit of the holographic correspondence, a
particular asymptotic limit of N=2, AdS_4 supergravity to N=2 supergravity on a
locally AdS_3 boundary. Our boundary theory enjoys OSp(2|2) x SO(1,2)
invariance and is shown to contain the D=3 super-Chern Simons OSp(2|2) theory
considered in [Alvarez:2011gd] and featuring "unconventional local
supersymmetry". The model constructed in that reference describes the dynamics
of a spin-1/2 Dirac field in the absence of spin 3/2 gravitini and was shown to
be relevant for the description of graphene, near the Dirac points, for
specific spatial geometries. Our construction yields the model in
[Alvarez:2011gd] with a specific prescription on the parameters. In this
framework the Dirac spin-1/2 fermion originates from the radial components of
the gravitini in D=4.Comment: 23 page
N=2 Supergravity Lagrangian Coupled to Tensor Multiplets with Electric and Magnetic Fluxes
We derive the full N=2 supergravity Lagrangian which contains a symplectic
invariant scalar potential in terms of electric and magnetic charges. As shown
in reference [1], the appearance of magnetic charges is allowed only if tensor
multiplets are present and a suitable Fayet-Iliopoulos term is included in the
fermion transformation laws. We generalize the procedure in the quoted
reference by adding further a Fayet-Iliopoulos term which allows the
introduction of electric charges in such a way that the potential and the
equations of motion of the theory are symplectic invariant. The theory is
further generalized to include an ordinary electric gauging and the form of the
resulting scalar potential is given.Comment: 1+34 pages LaTeX, correction of a typo in the ungauged scalar
potentia
Supersymmetric completion of M-theory 4D-gauge algebra from twisted tori and fluxes
We present the supersymmetric completion of the M-theory free differential
algebra resulting from a compactification to four dimensions on a twisted
seven-torus with 4-form and 7-form fluxes turned on. The super--curvatures are
given and the local supersymmetry transformations derived. Dual formulations of
the theory are discussed in connection with classes of gaugings corresponding
to diverse choices of vacua. This also includes seven dimensional
compactifications on more general spaces not described by group manifolds.Comment: 19 pages, LaTeX, typos corrected, references adde
De Sitter solutions in N=4 matter coupled supergravity
We investigate the scalar potential of gauged N=4 supergravity with matter.
The extremum in the SU(1,1)/U(1) scalars is obtained for an arbitrary number of
matter multiplets. The constraints on the matter scalars are solved in terms of
an explicit parametrisation of an
SO(6,6+n) element. For the case of six matter multiplets we discuss both
compact and noncompact gauge groups.
In an example involving noncompact groups and four scalars we find a
potential with an absolute minimum and a positive cosmological constant.Comment: 14 page
The Influence of Dependence on Data Network Models of Burstiness
The Influence of Dependence on Data Network Models of Burstines
Data Network Models of Burstiness
Data Network Models of Burstines
Lagrangians with electric and magnetic charges of N=2 supersymmetric gauge theories
General Lagrangians are constructed for N=2 supersymmetric gauge theories in
four space-time dimensions involving gauge groups with (non-abelian) electric
and magnetic charges. The charges induce a scalar potential, which, when the
charges are regarded as spurionic quantities, is invariant under
electric/magnetic duality. The resulting theories are especially relevant for
supergravity, but details of the extension to local supersymmetry will be
discussed elsewhere. The results include the coupling to hypermultiplets.
Without the latter, it is demonstrated how an off-shell representation can be
constructed based on vector and tensor supermultiplets.Comment: 34 pages, LaTe
MODELING OF DEFORMATION SOURCES BASED ON A NON-LINEAR INVERSION APPROACH
A new modeling of deformation sources based on a nonlinear
inversion approach is proposed. The forward
modeling is provided by the semi-analytic deformation
model for point sources and finite faults. The parameters
of the fault are inverted using a combination of nonlinear
optimization algorithms. The misfit function
defined for the optimization is based on the L2 norm of
the error weighted by the coherence of the considered
spatial point. In order to explain our modeling
procedure we propose the inversion of a single
descending pass differential interferogram of the Bam
2003 earthquake
Nuclear Energy and its History: Past Consequences, Present Inadequacies and a Perspective for Success
An attempt is made to locate nuclear technology within a logical context considering
history, risks, societal catastrophes and perspectives: the need is
identified for a new direction in the exploitation in order to restore the role in
energy production. We depict the situation coming from a marvelous history
of discoveries started at the beginning of the XX century; heroes are recalled
who made possible something that is inconceivable today: design, construction
and production of electricity in a few years; that history was tainted by
intentional nuclear explosions, i.e. the original sin that we are now paying.
Then, we attempt to show that the societal risk is an inherent part of the civilization.
Restoring the public trust (towards nuclear fission technology) by
matching nuclear safety with the current technological status and advancers
in risk assessment is the key objective. The “independent assessment”, or a
principle for the exploitation of nuclear energy already stated in the 50’s of
the previous century, shall then re-appear. This is used to erect the signpost
for a “dynamic barricade” to further reduce the risk of operation of nuclear
reactors and to match the design with current technological capabilities and
with the frontiers of the research
New turbulence modeling for simulation of Direct Contact Condensation in two-phase pressurized thermal shock
Injection of Emergency Core Cooling System (ECCS) water into the primary loops of the Pressurized Water
Reactors (PWRs) leads to rapid cooling of Reactor Pressure Vessel (RPV) inside wall after Loss Of Coolant
Accident (LOCA). This condition, known as Pressurized Thermal Shock (PTS) intensifies the propagation of the
RPV structural defects and would be considered as an ageing mechanism. For structural and fracture analysis of
RPV wall, thermal-hydraulic analysis of PTS should be accomplished to obtain the steam/water flow characteristics
in the downcomer. For this purpose, simulation of steam/water stratified flow (due to density difference)
after the injection point should be done by Computational Fluid Dynamics (CFD) methods. In this
region, steam condensation over water layer is considered as the only heat source and controlled by turbulence
eddy motion near the steam/water interface. Based on Surface Renewal Theory (SRT), Heat Transfer Coefficient
(HTC) would be calculated by evaluation of turbulence length and velocity. Therefore, prediction of turbulence
characteristics plays a significant role for estimation of interfacial mass transfer and temperature profile. High
gradient of velocity and Turbulence Kinetic Energy (TKE), and interfacial mass and momentum transfer at the
steam/water interface needs some modifications for application of traditional turbulence models.
Implementation of damping function is one of the common solutions to overcome the overestimation of TKE at
the steam/water interface. Although, this function improves flow characteristics of smooth stratified flow, investigation
of conservation equations and experimental data implies that the other source function is needed
when the flow regime changes to wavy flow. In this paper, a new source function of TKE based on variations of
turbulence characteristics is proposed for steam/water interface leading to a special boundary condition of
turbulence. To investigate the effects of this modification, simulation of air/water and steam/water stratified
flow in three different test facilities is performed. The results show that the implementation of the source
function of TKE improves the prediction of turbulence characteristics at the interface of isothermal stratified
flow. Also condensation rate and temperature gradient of steam/water stratified flow have a better agreement
with experimental data
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