55,275 research outputs found
Study of CMS sensitivity to neutrinoless decay at LHC
The Large Hadron Collider (LHC), scheduled to start operation in 2006, is
foreseen to provide in the first year of running a total of
leptons. CMS (Compact Muon Solenoid) is a general-purpose experiment
designed to study proton-proton and heavy-ion collisions at LHC. Even if the
Susy particles and Higgs searches togheter with the B-physics present its main
goal, the large amount of -lepton, could allow a systematic study of
tau-physics. We have performed a full simulation of CMS using GEANT 3 package
and the object-oriented reconstruction program ORCA to study the sensitivity to
neutrinoless tau decay and .
We present the analysis developed for these channels and the results obtained.Comment: Invited talk at the seventh international Workshop on tau lepton
physics (TAU02), Santa Cruz, Ca, Usa, September 2002 10 pages 15 eps figure
Closing Talk: QCD Moriond 2006
I comment on some theoretical work presented at QCD Moriond 2006.Comment: 11 pages, 9 figure
Growth of covariant perturbations in the contracting phase of a bouncing universe
In this paper we examine the validity of the linear perturbation theory near
a bounce in the covariant analysis. Some linearity parameters are defined to
set up conditions for a linear theory. Linear evolution of density perturbation
and gravitational waves have been computed previously. We have calculated the
vector and scalar induced parts of the shear tensor. For radiationlike and
dustlike single fluid dominated collapsing Friedmann-Lemaitre-Robertson-Walker
background it is shown that the linearity conditions are not satisfied near a
bounce.Comment: 9 pages, final versio
Inhomogeneity effects in Cosmology
This article looks at how inhomogeneous spacetime models may be significant
for cosmology. First it looks at how the averaging process may affect large
scale dynamics, with backreaction effects leading to effective contributions to
the averaged energy-momentum tensor. Secondly it considers how local
inhomogeneities may affect cosmological observations in cosmology, possibly
significantly affecting the concordance model parameters. Thirdly it presents
the possibility that the universe is spatially inhomogeneous on Hubble scales,
with a violation of the Copernican principle leading to an apparent
acceleration of the universe. This could perhaps even remove the need for the
postulate of dark energy.Comment: 29 pages. For special issue of CQG on inhomogeneous cosmologie
On the paradox of Hawking radiation in a maximally extended Schwarzschild solution
This paper considers the effect of Hawking radiation on an eternal black hole
- that is. a maximally extended Schwarzschild solution. Symmetry considerations
that hold independent of the details of the emission mechanism show there is an
inconsistency in the claim that such a blackhole evaporates away in a finite
time. In essence: because the external domain is static, there is an infinite
time available for the process to take place, so whenever the evaporation
process is claimed to come to completion, it should have happened earlier. The
problem is identified to lie in the claim that the locus of emission of Hawking
radiation lies just outside the globally defined event horizon. Rather, the
emission domain must be mainly located inside the event horizon, so most of the
Hawking radiation ends up at this singularity rather than at infinity and the
black hole never evaporates away. This result supports a previous claim
[arXiv:1310.4771] that astrophysical black holes do not evaporate.Comment: 26 pages, 7 figures, 2 tables. arXiv admin note: text overlap with
arXiv:1310.477
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