147,212 research outputs found
Strain gage circuitry provides fatigue testing machine with accurate cycle count
Fatigue tester determines the number of cycles to fatigue failure of brittle specimens. A strain gage on the loading arm records the loading applied to the component. As the component starts to break, the load is reduced and the strain gage stops the cycle counter
Exotic Smooth Structures on Small 4-Manifolds
Let M be either CP^2#3CP^2bar or 3CP^2#5CP^2bar. We construct the first
example of a simply-connected symplectic 4-manifold that is homeomorphic but
not diffeomorphic to M.Comment: 11 page
Non-Abelian Proca model based on the improved BFT formalism
We present the newly improved Batalin-Fradkin-Tyutin (BFT) Hamiltonian
formalism and the generalization to the Lagrangian formulation, which provide
the much more simple and transparent insight to the usual BFT method, with
application to the non-Abelian Proca model which has been an difficult problem
in the usual BFT method. The infinite terms of the effectively first class
constraints can be made to be the regular power series forms by ingenious
choice of and -matrices. In this new
method, the first class Hamiltonian, which also needs infinite correction terms
is obtained simply by replacing the original variables in the original
Hamiltonian with the BFT physical variables. Remarkably all the infinite
correction terms can be expressed in the compact exponential form. We also show
that in our model the Poisson brackets of the BFT physical variables in the
extended phase space are the same structure as the Dirac brackets of the
original phase space variables. With the help of both our newly developed
Lagrangian formulation and Hamilton's equations of motion, we obtain the
desired classical Lagrangian corresponding to the first class Hamiltonian which
can be reduced to the generalized St\"uckelberg Lagrangian which is non-trivial
conjecture in our infinitely many terms involved in Hamiltonian and Lagrangian.Comment: Notable improvements in Sec. I
Fermi Gamma Ray Line at 130 GeV from Axion-Mediated Dark Matter
We consider a singlet Dirac fermion with Peccei-Quinn(PQ) symmetry as dark
matter. A singlet complex scalar is introduced to mediate between dark matter
and the SM through Higgs portal interaction and electroweak PQ anomalies. We
show that a resonant annihilation of dark matter with axion mediation can
explain the monochromatic photon line of the Fermi LAT data at 130 GeV by
anomaly interactions while the annihilation cross section with Higgs portal
interaction is p-wave suppressed. We discuss the interplay between the direct
detection of the fermion dark matter and the collider search of Higgs-like
scalars. We also present a ultra-violet completion of the dark matter model
into the NMSSM with PQ symmetry.Comment: 22 pages, 9 figures, To be published in Phys. Rev.
Quantum Scalar Corrections to the Gravitational Potentials on de Sitter Background
We employ the graviton self-energy induced by a massless, minimally coupled
(MMC) scalar on de Sitter background to compute the quantum corrections to the
gravitational potentials of a static point particle with a mass . The
Schwinger-Keldysh formalism is used to derive real and causal effective field
equations. When evaluated at the one-loop order, the gravitational potentials
exhibit a secular decrease in the observed gravitational coupling . This can
also be interpreted as a (time dependent) anti-screening of the mass .Comment: 21 pages, uses LaTeX 2
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