5,474 research outputs found
Actions of arithmetic groups on homology spheres and acyclic homology manifolds
We establish lower bounds on the dimensions in which arithmetic groups with
torsion can act on acyclic manifolds and homology spheres. The bounds rely on
the existence of elementary p-groups in the groups concerned. In some cases,
including Sp(2n,Z), the bounds we obtain are sharp: if X is a generalized
Z/3-homology sphere of dimension less than 2n-1 or a Z/3-acyclic Z/3-homology
manifold of dimension less than 2n, and if n \geq 3, then any action of
Sp(2n,Z) by homeomorphisms on X is trivial; if n = 2, then every action of
Sp(2n,Z) on X factors through the abelianization of Sp(4,Z), which is Z/2.Comment: Final version, to appear in Math Zeitschrif
Improving Effective Surgical Delivery in Humanitarian Disasters: Lessons from Haiti
Kathryn Chu and colleagues describe the experiences of Médecins sans Frontières after the 2010 Haiti earthquake, and discuss how to improve delivery of surgery in humanitarian disasters
Two-dimensional model of dynamical fermion mass generation in strongly coupled gauge theories
We generalize the Schwinger model on the lattice by adding a charged
scalar field. In this so-called model the scalar field shields
the fermion charge, and a neutral fermion, acquiring mass dynamically, is
present in the spectrum. We study numerically the mass of this fermion at
various large fixed values of the gauge coupling by varying the effective
four-fermion coupling, and find an indication that its scaling behavior is the
same as that of the fermion mass in the chiral Gross-Neveu model. This suggests
that the model is in the same universality class as the
Gross-Neveu model, and thus renormalizable and asymptotic free at arbitrary
strong gauge coupling.Comment: 18 pages, LaTeX2e, requires packages rotating.sty and curves.sty from
CTA
The correction of the littlest Higgs model to the Higgs production process in collisions
The littlest Higgs model is the most economical one among various little
Higgs models. In the context of the littlest Higgs(LH) model, we study the
process and calculate the contributions of the
LH model to the cross section of this process. The results show that, in most
of parameter spaces preferred by the electroweak precision data, the value of
the relative correction is larger than 10%. Such correction to the process
is large enough to be detected via
collisions in the future high energy linear collider()
experiment with the c.m energy =500 GeV and a yearly integrated
luminosity , which will give an ideal way to test the
model.Comment: 13 pages, 4 figure
Numerical Study of Length Spectra and Low-lying Eigenvalue Spectra of Compact Hyperbolic 3-manifolds
In this paper, we numerically investigate the length spectra and the
low-lying eigenvalue spectra of the Laplace-Beltrami operator for a large
number of small compact(closed) hyperbolic (CH) 3-manifolds. The first non-zero
eigenvalues have been successfully computed using the periodic orbit sum
method, which are compared with various geometric quantities such as volume,
diameter and length of the shortest periodic geodesic of the manifolds. The
deviation of low-lying eigenvalue spectra of manifolds converging to a cusped
hyperbolic manifold from the asymptotic distribution has been measured by
function and spectral distance.Comment: 19 pages, 18 EPS figures and 2 GIF figures (fig.10) Description of
cusped manifolds in section 2 is correcte
On the Whitehead spectrum of the circle
The seminal work of Waldhausen, Farrell and Jones, Igusa, and Weiss and
Williams shows that the homotopy groups in low degrees of the space of
homeomorphisms of a closed Riemannian manifold of negative sectional curvature
can be expressed as a functor of the fundamental group of the manifold. To
determine this functor, however, it remains to determine the homotopy groups of
the topological Whitehead spectrum of the circle. The cyclotomic trace of B
okstedt, Hsiang, and Madsen and a theorem of Dundas, in turn, lead to an
expression for these homotopy groups in terms of the equivariant homotopy
groups of the homotopy fiber of the map from the topological Hochschild
T-spectrum of the sphere spectrum to that of the ring of integers induced by
the Hurewicz map. We evaluate the latter homotopy groups, and hence, the
homotopy groups of the topological Whitehead spectrum of the circle in low
degrees. The result extends earlier work by Anderson and Hsiang and by Igusa
and complements recent work by Grunewald, Klein, and Macko.Comment: 52 page
The littlest Higgs model and Higgs boson associated production with top quark pair at high energy linear collider
In the parameter space allowed by the electroweak precision measurement data,
we consider the contributions of the new particles predicted by the littlest
Higgs() model to the Higgs boson associated production with top quark pair
in the future high energy linear collider(). We find that the
contributions mainly come from the new gauge bosons and . For
reasonable values of the free parameters, the absolute value of the relative
correction parameter can be significanly large,
which might be observed in the future experiment with .Comment: latex files, 13 pages, 3 figure
Higgs boson pair production process in the littlest Higgs model at the ILC
The physics prospect at future linear colliders for the study of
the Higgs triple self-coupling via the process of is
investigated. In this paper, we calculate the contribution of the new particles
predicted by the littlest Higgs model to the cross sections of this process in
the future high energy collider(). The results show that, in
the favorable parameter spaces preferred by the electroweak precision, the
deviation of the total cross sections from its value varies from a few
percent to tens percent, which may be detected at the future experiments
with =500GeV.Comment: 13 pages,4 figure
Status of the GEO600 gravitational wave detector
The GEO600 laser interferometric gravitational wave detector is approaching the end of its commissioning phase which started in 1995.During a test run in January 2002 the detector was operated for 15 days in a power-recycled michelson configuration. The detector and environmental data which were acquired during this test run were used to test the data analysis code. This paper describes the subsystems of GEO600, the status of the detector by August 2002 and the plans towards the first science run
On Deformations of n-Lie algebras
The aim of this paper is to review the deformation theory of -Lie
algebras. We summarize the 1-parameter formal deformation theory and provide a
generalized approach using any unital commutative associative algebra as a
deformation base. Moreover, we discuss degenerations and quantization of
-Lie algebras.Comment: Proceeding of the conference Dakar's Workshop in honor of Pr Amin
Kaidi. arXiv admin note: text overlap with arXiv:hep-th/9602016 by other
author
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