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Evidence for dark energy: cross-correlating SDSS5 and WMAP3

A Cabre., E Gaztanaga., M Manera., P Fosalba., F Castander.
02 Nov 2006 astro-ph arxiv.org/abs/astro-ph/0611046

We cross-correlate the third-year WMAP data with galaxy samples extracted from the SDSS DR5 (SDSS5) covering 16% of the sky. These measurements confirm a positive cross-correlation, which is well fitted by the integrated Sachs-Wolfe (ISW) effect for flat LCDM models with a cosmological constant.

Web Pages Clustering: A New Approach

E Jeevan H, P Prashanth P, N Punith Kumar S, Hegde Vinay
26 Aug 2011 cs.IR arxiv.org/abs/1108.5703

The rapid growth of web has resulted in vast volume of information. Information availability at a rapid speed to the user is vital. English language (or any for that matter) has lot of ambiguity in the usage of words. So there is no guarantee that a keyword based search engine will provide the required results. This paper introduces the use of dictionary (standardised) to obtain the context with which a keyword is used and in turn cluster the results based on this context. These ideas can be merged with a metasearch engine to enhance the search efficiency.

On the Infrared Behavior of the Pressure in Thermal Field Theories

de Almeida A. P., Frenkel J.
19 Aug 1992 hep-ph hep-th arxiv.org/abs/hep-ph/9208234

We study non-perturbatively, via the Schwinger-Dyson equations, the leading infrared behavior of the pressure in the ladder approximation. This problem is discussed firstly in the context of a thermal scalar field theory, and the analysis is then extended to the Yang-Mills theory at high temperatures. Using the Feynman gauge, we find a system of two coupled integral equations for the gluon and ghost self-energies, which is solved analytically. The solutions of these equations show that the contributions to the pressure, when calculated in the ladder approximation, are finite in the infrared domain.

The 3-graviton vertex function in thermal quantum gravity

Brandt F. T., Frenkel J.
22 Sep 1992 hep-ph arxiv.org/abs/hep-ph/9209265

The high temperature limit of the 3-graviton vertex function is studied in thermal quantum gravity, to one loop order. The leading ($T^4$) contributions arising from internal gravitons are calculated and shown to be twice the ones associated with internal scalar particles, in correspondence with the two helicity states of the graviton. The gauge invariance of this result follows in consequence of the Ward and Weyl identities obeyed by the thermal loops, which are verified explicitly.

Dilogarithm identities, q-difference equations and the Virasoro algebra

Frenkel Edward, Szenes Andras
15 Dec 1992 hep-th math.QA arxiv.org/abs/hep-th/9212094

We give a new proof of the dilogarithm identities, associated to the (2,2n+1) minimal models of the Virasoro algebra.

Coinvariants of nilpotent subalgebras of the Virasoro algebra and partition identities

Feigin Boris, Frenkel Edward
12 Jan 1993 hep-th arxiv.org/abs/hep-th/9301039

We prove that the dimensions of coinvariants of certain nilpotent subalgebras of the Virasoro algebra do not change under deformation in the case of irreducible representations of (2,2r+1) minimal models. We derive a combinatorial description of these representations and the Gordon identities from this result.

Two dimensional black-hole as a topological coset model of c=1 string theory

Mukhi S., Vafa C., Frenkel E.
19 Jan 1993 hep-th arxiv.org/abs/hep-th/9301083

We show that a special superconformal coset (with $\hat c =3$) is equivalent to $c=1$ matter coupled to two dimensional gravity. This identification allows a direct computation of the correlation functions of the $c=1$ non-critical string to all genus, and at nonzero cosmological constant, directly from the continuum approach. The results agree with those of the matrix model. Moreover we connect our coset with a twisted version of a Euclidean two dimensional black hole, in which the ghost and matter systems are mixed.

Central extensions of current groups in two dimensions

Etingof Pavel, Frenkel Igor B.
08 Mar 1993 hep-th math.QA arxiv.org/abs/hep-th/9303047

In this paper we generalize some of these results for loop algebras and groups as well as for the Virasoro algebra to the two-dimensional case. We define and study a class of infinite dimensional complex Lie groups which are central extensions of the group of smooth maps from a two dimensional orientable surface without boundary to a simple complex Lie group G. These extensions naturally correspond to complex curves. The kernel of such an extension is the Jacobian of the curve. The study of the coadjoint action shows that its orbits are labelled by moduli of holomorphic principal G-bundles over the curve and can be described in the language of partial differential equations. In genus one it is also possible to describe the orbits as conjugacy classes of the twisted loop group, which leads to consideration of difference equations for holomorphic functions. This gives rise to a hope that the described groups should possess a counterpart of the rich representation theory that has been developed for loop groups. We also define a two-dimensional analogue of the Virasoro algebra associated with a complex curve. In genus one, a study of a complex analogue of Hill's operator yields a description of invariants of the coadjoint action of this Lie algebra. The answer turns out to be the same as in dimension one: the invariants coincide with those for the extended algebra of currents in sl(2).

Crystal bases, dilogarithm identities and torsion in algebraic K-groups

Frenkel Edward, Szenes Andras
25 Apr 1993 hep-th math.QA arxiv.org/abs/hep-th/9304118

We give a new interpretation and proof of the dilogarithm identities, associated to the affine Kac-Moody algebra sl(2)^, using the path description of the corresponding crystal basis. We also discuss connections with algebraic K-theory.

The graviton self-energy in thermal quantum gravity

Brandt F. T., Frenkel J.
26 May 1993 hep-th arxiv.org/abs/hep-th/9305147

We show generally that in thermal gravity, the one-particle irreducible 2-point function depends on the choice of the basic graviton fields. We derive the relevant properties of a physical graviton self-energy, which is independent of the parametrization of the graviton field. An explicit expression for the graviton self-energy at high-temperature is given to one-loop order.