نتایج جستجو برای: weyl

تعداد نتایج: 9437  

2008
Johannes Sjöstrand

This text is a survey of recent results obtained by the author and collaborators on different problems for non-self-adjoint operators. The topics are: Kramers-Fokker-Planck type operators, spectral asymptotics in two dimensions and Weyl asymptotics for the eigenvalues of non-self-adjoint operators with small random perturbations. In the introduction we also review the notion of pseudo-spectrum ...

Journal: :Int. J. Math. Mathematical Sciences 2006
N. B. Hamadi Lakhdar T. Rachdi

In his book [14], Wong studies the properties of pseudodifferential operators arising in quantummechanics, first envisaged byWeyl [13], as bounded linear operators on L2(Rn) (the space of square integrable functions on Rn with respect to the Lebesgue measure). For this reason, M. W. Wong calls the operators treated in his book Weyl transforms. Here, we consider the singular partial differential...

2009
CARLO A. ROSSI

We prove a version of Kontsevich’s formality theorem for two subspaces (branes) of a vector space X. The result implies in particular that the Kontsevich deformation quantizations of S(X∗) and ∧(X) associated with a quadratic Poisson structure are Koszul dual. This answers an open question in Shoikhet’s recent paper on Koszul duality in deformation quantization.

2012
M. Lafourcade

Let A be a sub-uncountable scalar. Recent developments in formal K-theory [20] have raised the question of whether every ordered topological space is additive. We show that 1 0 6= 1. Every student is aware that there exists a nonnegative and anti-injective factor. We wish to extend the results of [20] to Weyl functors.

2008
A. C. Lungu

The cross-couplings among several Weyl gravitons (described in the free limit by a sum of linearized Weyl actions) in the presence of a scalar field are studied with the help of the deformation theory based on local BRST cohomology. Under the hypotheses of locality, smoothness of the interactions in the coupling constant, Poincaré invariance, (background) Lorentz invariance, and the preservatio...

2010
Aleksey Kostenko Alexander Sakhnovich Gerald Teschl

We develop Weyl–Titchmarsh theory for Schrödinger operators with strongly singular potentials such as perturbed spherical Schrödinger operators (also known as Bessel operators). It is known that in such situations one can still define a corresponding singular Weyl m-function and it was recently shown that there is also an associated spectral transformation. Here we will give a general criterion...

2007
R. M. Green Robert Marsh

We use the author’s combinatorial theory of full heaps to categorify the action of a large class of Weyl groups on their root systems, and thus to give an elementary and uniform construction of a family of faithful permutation representations of Weyl groups. Examples include the standard representations of affine Weyl groups as permutations of Z and geometrical examples such as the realization ...

2016
Cheng-Long Zhang Su-Yang Xu Ilya Belopolski Zhujun Yuan Ziquan Lin Bingbing Tong Guang Bian Nasser Alidoust Chi-Cheng Lee Shin-Ming Huang Tay-Rong Chang Guoqing Chang Chuang-Han Hsu Horng-Tay Jeng Madhab Neupane Daniel S Sanchez Hao Zheng Junfeng Wang Hsin Lin Chi Zhang Hai-Zhou Lu Shun-Qing Shen Titus Neupert M Zahid Hasan Shuang Jia

Weyl semimetals provide the realization of Weyl fermions in solid-state physics. Among all the physical phenomena that are enabled by Weyl semimetals, the chiral anomaly is the most unusual one. Here, we report signatures of the chiral anomaly in the magneto-transport measurements on the first Weyl semimetal TaAs. We show negative magnetoresistance under parallel electric and magnetic fields, t...

Journal: :Nature materials 2016
Max Hirschberger Satya Kushwaha Zhijun Wang Quinn Gibson Sihang Liang Carina A Belvin B A Bernevig R J Cava N P Ong

The Dirac and Weyl semimetals are unusual materials in which the nodes of the bulk states are protected against gap formation by crystalline symmetry. The chiral anomaly, predicted to occur in both systems, was recently observed as a negative longitudinal magnetoresistance (LMR) in Na3Bi (ref. ) and in TaAs (ref. ). An important issue is whether Weyl physics appears in a broader class of materi...

2013
N. S. Narasimha Sastry

Each symplectic group over the field of two elements has two exceptional doubly transitive actions on sets of quadratic forms on the defining symplectic vector space. This paper studies the associated 2-modular permutation modules. Filtrations of these modules are constructed which have subquotients which are modules for the symplectic group over an algebraically closed field of characteristic ...

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