2,448 research outputs found
Two-Dimensional N=(2,2) Dilaton Supergravity from Graded Poisson-Sigma Models I: Complete Actions and Their Symmetries
The formalism of graded Poisson-sigma models allows the construction of
N=(2,2) dilaton supergravity in terms of a minimal number of fields. For the
gauged chiral U(1) symmetry the full action, involving all fermionic
contributions, is derived. The twisted chiral case follows by simple
redefinition of fields. The equivalence of our approach to the standard second
order one in terms of superfields is presented, although for the latter so far
only the bosonic part of the action seems to have been available in the
literature. It is shown how ungauged models can be obtained in a systematic way
and some relations to relevant literature in superstring theory are discussed.Comment: 26 p., LaTeX. v3: extended version, new title, new section on
ungauged model
Absolute conservation law for black holes
In all 2d theories of gravity a conservation law connects the (space-time
dependent) mass aspect function at all times and all radii with an integral of
the matter fields. It depends on an arbitrary constant which may be interpreted
as determining the initial value together with the initial values for the
matter field. We discuss this for spherically reduced Einstein-gravity in a
diagonal metric and in a Bondi-Sachs metric using the first order formulation
of spherically reduced gravity, which allows easy and direct fixations of any
type of gauge. The relation of our conserved quantity to the ADM and Bondi mass
is investigated. Further possible applications (ideal fluid, black holes in
higher dimensions or AdS spacetimes etc.) are straightforward generalizations.Comment: LaTex, 17 pages, final version, to appear in Phys. Rev.
Minimal long-term neurobehavioral impairments after endovascular perforation subarachnoid hemorrhage in mice
AbstractCognitive deficits are among the most severe and pervasive consequences of aneurysmal subarachnoid hemorrhage (SAH). A critical step in developing therapies targeting such outcomes is the characterization of experimentally-tractable pre-clinical models that exhibit multi-domain neurobehavioral deficits similar to those afflicting humans. We therefore searched for neurobehavioral abnormalities following endovascular perforation induction of SAH in mice, a heavily-utilized model. We instituted a functional screen to manage variability in injury severity, then assessed acute functional deficits, as well as activity, anxiety-related behavior, learning and memory, socialization, and depressive-like behavior at sub-acute and chronic time points (up to 1 month post-injury). Animals in which SAH was induced exhibited reduced acute functional capacity and reduced general activity to 1 month post-injury. Tests of anxiety-related behavior including central area time in the elevated plus maze and thigmotaxis in the open field test revealed increased anxiety-like behavior at subacute and chronic time-points, respectively. Effect sizes for subacute and chronic neurobehavioral endpoints in other domains, however, were small. In combination with persistent variability, this led to non-significant effects of injury on all remaining neurobehavioral outcomes. These results suggest that, with the exception of anxiety-related behavior, alternate mouse models are required to effectively analyze cognitive outcomes after SAH.</jats:p
Two-Dimensional N=(2,2) Dilaton Supergravity from Graded Poisson-Sigma Models II: Analytic Solution and BPS States
The integrability of N=(2,2) dilaton supergravity in two dimensions is
studied by the use of the graded Poisson Sigma model approach. Though important
differences compared to the purely bosonic models are found, the general
analytic solutions are obtained. The latter include minimally gauged models as
well as an ungauged version. BPS solutions are an especially interesting
subclass.Comment: 23 p LaTe
New Bound States of Heavy Quarks at LHC and Tevatron
The present paper is based on the assumption that heavy quarks bound states
exist in the Standard Model (SM). Considering New Bound States (NBS) of
top-anti-top quarks (named T-balls) we have shown that: 1) there exists the
scalar 1S--bound state of ; 2) the forces which bind the top-quarks
are very strong and almost completely compensate the mass of the twelve
top-anti-top-quarks in the scalar NBS; 3) such strong forces are produced by
the Higgs-top-quarks interaction with a large value of the top-quark Yukawa
coupling constant . Theory also predicts the existence of the NBS
, which is a color triplet and a fermion similar to the
-quark of the fourth generation. We have also considered the
"b-quark-replaced" NBS, estimated the masses of the lightest fermionic NBS:
GeV, and discussed the larger masses of T-balls. We have
developed a theory of the scalar T-ball's condensate and predicted the
existence of three SM phases. Searching for heavy quark bound states at the
Tevatron and LHC is discussed. We have constructed the possible form-factors of
T-balls, and estimated the charge multiplicity coming from the T-ball's decays.Comment: 25 pages 12 figure
modCHIMERA: A novel murine closed-head model of moderate traumatic brain injury
AbstractTraumatic brain injury is a major source of global disability and mortality. Preclinical TBI models are a crucial component of therapeutic investigation. We report a tunable, monitored model of murine non-surgical, diffuse closed-head injury—modCHIMERA—characterized by impact as well as linear and rotational acceleration. modCHIMERA is based on the Closed-Head Impact Model of Engineered Rotational Acceleration (CHIMERA) platform. We tested this model at 2 energy levels: 1.7 and 2.1 Joules—substantially higher than previously reported for this system. Kinematic analysis demonstrated linear acceleration exceeding injury thresholds in humans, although outcome metrics tracked impact energy more closely than kinematic parameters. Acute severity metrics were consistent with a complicated-mild or moderate TBI, a clinical population characterized by high morbidity but potentially reversible pathology. Axonal injury was multifocal and bilateral, neuronal death was detected in the hippocampus, and microglial neuroinflammation was prominent. Acute functional analysis revealed prolonged post-injury unconsciousness, and decreased spontaneous behavior and stimulated neurological scores. Neurobehavioral deficits were demonstrated in spatial learning/memory and socialization at 1-month. The overall injury profile of modCHIMERA corresponds with the range responsible for a substantial portion of TBI-related disability in humans. modCHIMERA should provide a reliable platform for efficient analysis of TBI pathophysiology and testing of treatment modalities.</jats:p
The Complete Solution of 2D Superfield Supergravity from graded Poisson-Sigma Models and the Super Pointparticle
Recently an alternative description of 2d supergravities in terms of graded
Poisson-Sigma models (gPSM) has been given. As pointed out previously by the
present authors a certain subset of gPSMs can be interpreted as "genuine"
supergravity, fulfilling the well-known limits of supergravity, albeit deformed
by the dilaton field. In our present paper we show that precisely that class of
gPSMs corresponds one-to-one to the known dilaton supergravity superfield
theories presented a long time ago by Park and Strominger. Therefore, the
unique advantages of the gPSM approach can be exploited for the latter: We are
able to provide the first complete classical solution for any such theory. On
the other hand, the straightforward superfield formulation of the point
particle in a supergravity background can be translated back into the gPSM
frame, where "supergeodesics" can be discussed in terms of a minimal set of
supergravity field degrees of freedom. Further possible applications like the
(almost) trivial quantization are mentioned.Comment: 48 pages, 1 figure. v3: after final version, typos correcte
Universal conservation law and modified Noether symmetry in 2d models of gravity with matter
It is well-known that all 2d models of gravity---including theories with
nonvanishing torsion and dilaton theories---can be solved exactly, if matter
interactions are absent. An absolutely (in space and time) conserved quantity
determines the global classification of all (classical) solutions. For the
special case of spherically reduced Einstein gravity it coincides with the mass
in the Schwarzschild solution. The corresponding Noether symmetry has been
derived previously by P. Widerin and one of the authors (W.K.) for a specific
2d model with nonvanishing torsion. In the present paper this is generalized to
all covariant 2d theories, including interactions with matter. The related
Noether-like symmetry differs from the usual one. The parameters for the
symmetry transformation of the geometric part and those of the matterfields are
distinct. The total conservation law (a zero-form current) results from a two
stage argument which also involves a consistency condition expressed by the
conservation of a one-form matter ``current''. The black hole is treated as a
special case.Comment: 3
High-energy magnetic excitations in overdoped LaSrCuO studied by neutron and resonant inelastic X-ray scattering
We have performed neutron inelastic scattering and resonant inelastic X-ray
scattering (RIXS) at the Cu- edge to study high-energy magnetic
excitations at energy transfers of more than 100 meV for overdoped
LaSrCuO with ( K) and
(non-superconducting) using identical single crystal samples for the two
techniques. From constant-energy slices of neutron scattering cross-sections,
we have identified magnetic excitations up to ~250 meV for . Although
the width in the momentum direction is large, the peak positions along the (pi,
pi) direction agree with the dispersion relation of the spin-wave in the
non-doped LaCuO (LCO), which is consistent with the previous RIXS
results of cuprate superconductors. Using RIXS at the Cu- edge, we have
measured the dispersion relations of the so-called paramagnon mode along both
(pi, pi) and (pi, 0) directions. Although in both directions the neutron and
RIXS data connect with each other and the paramagnon along (pi, 0) agrees well
with the LCO spin-wave dispersion, the paramagnon in the (pi, pi) direction
probed by RIXS appears to be less dispersive and the excitation energy is lower
than the spin-wave of LCO near (pi/2, pi/2). Thus, our results indicate
consistency between neutron inelastic scattering and RIXS, and elucidate the
entire magnetic excitation in the (pi, pi) direction by the complementary use
of two probes. The polarization dependence of the RIXS profiles indicates that
appreciable charge excitations exist in the same energy range of magnetic
excitations, reflecting the itinerant character of the overdoped sample. A
possible anisotropy in the charge excitation intensity might explain the
apparent differences in the paramagnon dispersion in the (pi, pi) direction as
detected by the X-ray scattering.Comment: 7 pages, 7 figure
Classical and Quantum Integrability of 2D Dilaton Gravities in Euclidean space
Euclidean dilaton gravity in two dimensions is studied exploiting its
representation as a complexified first order gravity model. All local classical
solutions are obtained. A global discussion reveals that for a given model only
a restricted class of topologies is consistent with the metric and the dilaton.
A particular case of string motivated Liouville gravity is studied in detail.
Path integral quantisation in generic Euclidean dilaton gravity is performed
non-perturbatively by analogy to the Minkowskian case.Comment: 27 p., LaTeX, v2: included new refs. and a footnot
- …