5,683 research outputs found
Hamiltonian versus Lagrangian formulations of supermechanic
We take advantage of different generalizations of the tangent manifold to the
context of graded manifolds, together with the notion of super section along a
morphism of graded manifolds, to obtain intrinsic definitions of the main
objects in supermechanics such as, the vertical endomorphism, the canonical and
the Cartan's graded forms, the total time derivative operator and the
super--Legendre transformation. In this way, we obtain a correspondence between
the Lagrangian and the Hamiltonian formulations of supermechanics.Comment: Plain TeX, 24 pages. Submitted to J. Phys.
Thin-shell wormholes with charge in F(R) gravity
In this article, we construct a class of constant curvature and spherically
symmetric thin-shell Lorentzian wormholes in F(R) theories of gravity and we
analyze their stability under perturbations preserving the symmetry. We find
that the junction conditions determine the equation of state of the matter at
the throat. As a particular case, we consider configurations with mass and
charge. We obtain that stable static solutions are possible for suitable values
of the parameters of the model.Comment: 10 pages, 2 figures; v2: minor changes, 1 new reference adde
Thin-shell wormholes with a double layer in quadratic F(R) gravity
We present a family of spherically symmetric Lorentzian wormholes in
quadratic F(R) gravity, with a thin shell of matter corresponding to the
throat. At each side of the shell the geometry has a different constant value
of the curvature scalar R. The junction conditions determine the equation of
state between the pressure and energy density at the throat, where a double
layer is also located. We analyze the stability of the configurations under
perturbations preserving the spherical symmetry. In particular, we study
thin-shell wormholes with mass and charge. We find that there exist values of
the parameters for which stable static solutions are possible.Comment: 12 pages, 2 figures; v3: improved version, 1 new reference adde
A geometric construction of the exceptional Lie algebras F4 and E8
We present a geometric construction of the exceptional Lie algebras F4 and E8
starting from the round 8- and 15-spheres, respectively, inspired by the
construction of the Killing superalgebra of a supersymmetric supergravity
background. (There is no supergravity in the paper.)Comment: 12 page
Complementarity of dark matter detectors in light of the neutrino background
Direct detection dark matter experiments looking for WIMP-nucleus elastic
scattering will soon be sensitive to an irreducible background from neutrinos
which will drastically affect their discovery potential. Here we explore how
the neutrino background will affect future ton-scale experiments considering
both spin-dependent and spin-independent interactions. We show that combining
data from experiments using different targets can improve the dark matter
discovery potential due to target complementarity. We find that in the context
of spin-dependent interactions, combining results from several targets can
greatly enhance the subtraction of the neutrino background for WIMP masses
below 10 GeV/c and therefore probe dark matter models to lower
cross-sections. In the context of target complementarity, we also explore how
one can tune the relative exposures of different target materials to optimize
the WIMP discovery potential.Comment: 13 pages, 12 figures, 3 table
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