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49

Sep 22, 2013
09/13

by
Krzysztof G. Hełminiak

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We study the impact of the atmospheric differential chromatic refraction on the measurements and precision of relative astrometry. Specifically, we address the problem of measuring the separations of close pairs of binary stars with adaptive optics in the J and K bands. We investigate the influence of weather conditions, zenithal distance, star's spectral type and observing wavelength on the astrometric precision and determine the accuracy of these parameters that is necessary to detect...

Source: http://arxiv.org/abs/0805.3369v3

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48

Sep 23, 2013
09/13

by
Daniel Allcock

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We prove the following: there are infinitely many finite-covolume (resp. cocompact) Coxeter groups acting on hyperbolic space H^n for every n < 20 (resp. n < 7). When n=7 or 8, they may be taken to be nonarithmetic. Furthermore, for 1 < n < 20, with the possible exceptions n=16 and 17, the number of essentially distinct Coxeter groups in H^n with noncompact fundamental domain of volume less than or equal to V grows at least exponentially with respect to V. The same result holds for...

Source: http://arxiv.org/abs/0903.0138v2

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34

Sep 23, 2013
09/13

by
Victor Beresnevich; Sanju Velani; Robert C. Vaughan

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The inhomogeneous metric theory for the set of simultaneously $\psi$-approximable points lying on a planar curve is developed. Our results naturally incorporate the homogeneous Khintchine-Jarnik type theorems recently established in [Ann. of Math. (2), 166 (2007), pp. 367-426] and [Invent. Math., 166 (2006), pp. 103-124]. The key lies in obtaining essentially the best possible results regarding the distribution of `shifted' rational points near planar curves.

Source: http://arxiv.org/abs/0903.2817v1

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69

Sep 21, 2013
09/13

by
Nikolay Gromov; Vladimir Kazakov; Pedro Vieira

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We present a set of functional equations defining the anomalous dimensions of arbitrary local single trace operators in planar N=4 SYM theory. It takes the form of a Y-system based on the integrability of the dual superstring sigma-model on the AdS_5xS^5 background. This Y-system passes some very important tests: it incorporates the full asymptotic Bethe ansatz at large length of operator L, including the dressing factor, and it confirms all recently found wrapping corrections. The recently...

Source: http://arxiv.org/abs/0901.3753v3

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32

Sep 21, 2013
09/13

by
Avinash Dhar; Partha Nag

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We discuss chiral symmetry breaking in the intersecting brane model of Sakai and Sugimoto at weak coupling for a generic value of separation $L$ between the flavour $D8$ and anti-$D8$-branes. For any finite value of the radius $R$ of the circle around which the colour $D4$-branes wrap, a non-local Nambu$-$Jona-Lasinio (NJL) type short-range interaction couples the flavour branes and anti-branes. We argue that chiral symmetry is broken in this model only above a certain critical value of the...

Source: http://arxiv.org/abs/0901.4942v2

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43

Sep 23, 2013
09/13

by
A. Morozov; Sh. Shakirov

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The simplest partition function, associated with homogeneous symmetric forms S of degree r in n variables, is integral discriminant J_{n|r}(S) = \int e^{-S(x_1 ... x_n)} dx_1 ... dx_n. Actually, S-dependence remains the same if e^{-S} in the integrand is substituted by arbitrary function f(S), i.e. integral discriminant is a characteristic of the form S itself, and not of the averaging procedure. The aim of the present paper is to calculate J_{n|r} in a number of non-Gaussian cases. Using Ward...

Source: http://arxiv.org/abs/0903.2595v1

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41

Sep 23, 2013
09/13

by
Arie Leizarowitz

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The paper is concerned with estimating the number of integers smaller than $x$ whose largest prime divisor is smaller than $y$, denoted $\psi (x,y)$. Much of the related literature is concerned with approximating $\psi (x,y)$ by Dickman's function $\rho (u)$, where $u=\ln x/\ln y$. A typical such result is that $$ \psi (x,y)=x\rho (u)(1+o(1)) \eqno (1) $$ in a certain domain of the parameters $x$ and $y$. In this paper a different type of approximation of $\psi (x,y)$, using iterated logarithms...

Source: http://arxiv.org/abs/0903.2712v1

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24

Sep 21, 2013
09/13

by
A. Yamasaki; S. Imada; K. Takase; T. Muro; Y. Kato; H. Kobori; A. Sugimura; N. Umeyama; H. Sato; Y. Hara; N. Miyakawa; S. I. Ikeda

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We have investigated the electronic structures of newly discovered superconductor FeSe1-x by bulk-sensitive photoemission spectroscopy (PES). The large Fe 3d spectral weight is located in the vicinity of the Fermi level (EF) and it decreases steeply toward EF . Compared with results of band structure calculations, narrowing the Fe 3d band width and the energy shift of the band toward EF are found, suggesting a mass enhancement due to the weak electron correlation effect. Meanwhile, Fe 2p...

Source: http://arxiv.org/abs/0902.3314v3