1,087 research outputs found
Algebraic structures on graph cohomology
We define algebraic structures on graph cohomology and prove that they
correspond to algebraic structures on the cohomology of the spaces of
imbeddings of S^1 or R into R^n. As a corollary, we deduce the existence of an
infinite number of nontrivial cohomology classes in Imb(S^1,R^n) when n is even
and greater than 3. Finally, we give a new interpretation of the anomaly term
for the Vassiliev invariants in R^3.Comment: Typos corrected, exposition improved. 14 pages, 2 figures. To appear
in J. Knot Theory Ramification
O Homem Espelho do Cosmo no Timeu de Platão. Os reflexos da cosmologia na formação e na constituição do homem
RESUMO
Este estudo tem como objetivo geral mostrar a relação entre macrocosmo e
microcosmo, especialmente em sua constituição física e psíquica. De maneira
mais específica, a pesquisa pretende examinar a causa do cosmo e do homem
(Demiurgo); a causa da constituição física do cosmo e do homem (Demiurgo e
deuses menores); a constituição psíquica do cosmo e do homem (Alma do
Mundo, alma humana e sua partição); o desequilíbrio entre cosmo e homem e
suas consequências (doença, envelhecimento e morte). Para tanto, abordaremos
o estudo do Timeu, o diálogo em que Platão destaca a unidade corpo-alma,
sendo analisada a formação do cosmo e da Alma do Mundo em primeiro lugar (T.
29d-40d; 47e-69a) e, logo em seguida, a constituição do homem, como reflexo do
cosmo (T. 40d-47e, 69a-81e) e a formação da alma humana. A fim de dar
consecução ao objeto da pesquisa adotar-se-á como metodologia de estudo um
procedimento monográfico ancorado em pesquisa bibliográfica.
Palavras-chave: Platão. Timeu. Cosmologia. Psicologia. Fisiologia. Ética
Link Invariants of Finite Type and Perturbation Theory
The Vassiliev-Gusarov link invariants of finite type are known to be closely
related to perturbation theory for Chern-Simons theory. In order to clarify the
perturbative nature of such link invariants, we introduce an algebra V_infinity
containing elements g_i satisfying the usual braid group relations and elements
a_i satisfying g_i - g_i^{-1} = epsilon a_i, where epsilon is a formal variable
that may be regarded as measuring the failure of g_i^2 to equal 1.
Topologically, the elements a_i signify crossings. We show that a large class
of link invariants of finite type are in one-to-one correspondence with
homogeneous Markov traces on V_infinity. We sketch a possible application of
link invariants of finite type to a manifestly diffeomorphism-invariant
perturbation theory for quantum gravity in the loop representation.Comment: 11 page
Topological BF Theories in 3 and 4 Dimensions
In this paper we discuss topological BF theories in 3 and 4 dimensions.
Observables are associated to ordinary knots and links (in 3 dimensions) and to
2-knots (in 4 dimensions). The vacuum expectation values of such observables
give a wide range of invariants. Here we consider mainly the 3-dimensional
case, where these invariants include Alexander polynomials, HOMFLY polynomials
and Kontsevich integrals.Comment: 25 pages, latex, no figures. Transmission problems have been solve
4-Dimensional BF Theory as a Topological Quantum Field Theory
Starting from a Lie group G whose Lie algebra is equipped with an invariant
nondegenerate symmetric bilinear form, we show that 4-dimensional BF theory
with cosmological term gives rise to a TQFT satisfying a generalization of
Atiyah's axioms to manifolds equipped with principal G-bundle. The case G =
GL(4,R) is especially interesting because every 4-manifold is then naturally
equipped with a principal G-bundle, namely its frame bundle. In this case, the
partition function of a compact oriented 4-manifold is the exponential of its
signature, and the resulting TQFT is isomorphic to that constructed by Crane
and Yetter using a state sum model, or by Broda using a surgery presentation of
4-manifolds.Comment: 15 pages in LaTe
Determining Ratios of WIMP-Nucleon Cross Sections from Direct Dark Matter Detection Data
Weakly Interacting Massive Particles (WIMPs) are one of the leading
candidates for Dark Matter. So far the usual procedure for constraining the
WIMP-nucleon cross sections in direct Dark Matter detection experiments have
been to fit the predicted event rate based on some model(s) of the Galactic
halo and of WIMPs to experimental data. One has to assume whether the
spin-independent (SI) or the spin-dependent (SD) WIMP-nucleus interaction
dominates, and results of such data analyses are also expressed as functions of
the as yet unknown WIMP mass. In this article, I introduce methods for
extracting information on the WIMP-nucleon cross sections by considering a
general combination of the SI and SD interactions. Neither prior knowledge
about the local density and the velocity distribution of halo WIMPs nor about
their mass is needed. Assuming that an exponential-like shape of the recoil
spectrum is confirmed from experimental data, the required information are only
the measured recoil energies (in low energy ranges) and the number of events in
the first energy bin from two or more experiments.Comment: 33 pages, 20 eps figures; v2: typos fixed, references added and
updated, revised version for publicatio
Machado de Assis e sua leitora Nise da Silveira
Nesse artigo, estaremos trabalhando com duas áreas de conhecimento: Literatura e Psicologia Junguiana. Nossa proposta é interdisciplinar: pretendemos analisar dois contos intitulados, O espelho e A causa secreta, do escritor brasileiro Machado de Assis, a partir dos trabalhos junguianos da psiquiatra brasileira Nise da Silveira
A Monte-Carlo study of the AdS/CFT correspondence: an exploration of quantum gravity effects
In this paper we study the AdS/CFT correspondence for N=4 SYM with gauge
group U(N), compactified on S^3 in four dimensions using Monte-Carlo
techniques. The simulation is based on a particular reduction of degrees of
freedom to commuting matrices of constant fields, and in particular, we can
write the wave functions of these degrees of freedom exactly. The square of the
wave function is equivalent to a probability density for a Boltzman gas of
interacting particles in six dimensions. From the simulation we can extract the
density particle distribution for each wave function, and this distribution can
be interpreted as a special geometric locus in the gravitational dual. Studying
the wave functions associated to half-BPS giant gravitons, we are able to show
that the matrix model can measure the Planck scale directly. We also show that
the output of our simulation seems to match various theoretical expectations in
the large N limit and that it captures 1/N effects as statistical fluctuations
of the Boltzman gas with the expected scaling. Our results suggest that this is
a very promising approach to explore quantum corrections and effects in
gravitational physics on AdS spaces.Comment: 40 pages, 7 figures, uses JHEP. v2: references adde
Chern-Simons States at Genus One
We present a rigorous analysis of the Schr\"{o}dinger picture quantization
for the Chern-Simons theory on 3-manifold torusline, with
insertions of Wilson lines. The quantum states, defined as gauge covariant
holomorphic functionals of smooth -connections on the torus, are
expressed by degree theta-functions satisfying additional conditions. The
conditions are obtained by splitting the space of semistable
-connections into nine submanifolds and by analyzing the behavior of
states at four codimension strata. We construct the
Knizhnik-Zamolodchikov-Bernard connection allowing to compare the states for
different complex structures of the torus and different positions of the Wilson
lines. By letting two Wilson lines come together, we prove a recursion relation
for the dimensions of the spaces of states which, together with the (unproven)
absence of states for spins\s>{_1\over^2}level implies the Verlinde dimension
formula.Comment: 33 pages, IHES/P
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