arXiv subjects
Publications and source records attributed to A. N. Sergeev.
M. Gorelik and Th. Heidersdors in the papers \cite{GH} investigated Euler characters for Lie superalgebra $\frak{gl}(m,n)$ and $\frak{osp}(m.2n)$. In the present paper we also investigate Euler characters for Lie superalgebra $\frak{gl}(m,n)$ but we use a different approach and our results are formulated in different terms.
The generation of relativistic vortex electron beams via photoemission requires ultraviolet laser beams with well-controlled orbital angular momentum (OAM) and compatibility with radio-frequency (RF) photoinjector drive-laser systems. High-OAM vortex beams at a wavelength of 266 nm are generated using three fabricated diffractive optical elements integrated into an operational photoinjector beamline: a reflective fork grating, a high-topological-charge spiral phase plate, and binary axicons. The spiral phase plate produces a high-purity Laguerre-Gaussian mode with an OAM of l = 64 and a conversion efficiency of 80%, whereas binary axicons generate low-divergence quasi-Bessel beams forming a superposition of multiple OAM states with a finite OAM bandwidth imposed by their binary phase structure. Fork gratings provide flexible access to lower OAM values and enable robust modal diagnostics. The generated beams are characterized using cylindrical-lens mode conversion and radial intensity analysis, demonstrating practical control of both the OAM content and spectral bandwidth of ultraviolet structured light for accelerator-based applications.
We present the development and experimental implementation of diffractive optical elements designed to generate optical vortices in the deep ultraviolet range (from 260 to 266 nm). These elements, fabricated using advanced lithographic and etching techniques, facilitate the efficient transformation of Gaussian beams into twisted modes carrying orbital angular momentum. Experimental tests conducted using the laser driver of an RF photoinjector at JINR successfully demonstrate the generation of deep-ultraviolet optical vortices with a topological charge of l = 1. These findings underscore the potential of structured light in the deep ultraviolet range for applications in relativistic electron beam studies and beam manipulation technologies.
An explicit formula for the canonical bilinear form on the Grothendieck ring of the Lie supergroup $GL(n,m)$ is given. As an application we get an algorithm for the decomposition Euler characters in terms of characters of irreducible modules in the category of partially polynomial representations.
We consider three types of rings of supersymmetric polynomials: polynomial ones $Λ_{m,n}$, partially polynomial $Λ_{m,n}^{+y}$ and Laurent supersymmetric rings $Λ_{m,n}^{\pm}$. For each type of rings we give their descriptions in terms of generators and relations. As a corollary we get for $n\ge m$ an isomorphism $Λ_{m,n}^{+y}=Λ_{m,m}^{+y}\otimesΛ^{+y}_{0,n-m}$. We also have the same sort of isomorphism for polynomial rings, but in this case the isomorphism does not preserve the grading. For each type of rings we also construct some natural basis consisting of Euler characters.
Coefficients of super Jacobi polynomials of type $B(1,n)$ are rational functions in three parameters $k,p,q$. At the point $(-1,0,0)$ these coefficient may have poles. Let us set $q=0$ and consider pair $(k,p)$ as a point of $\Bbb A^2$. If we apply blow up procedure at the point $(-1,0)$ then we get a new family of polynomials depending on parameter $t\in \Bbb P$. If $t=\infty$ then we get supercharacters of Kac modules for Lie supergroup $OSP(2,2n)$ and supercharacters of irreducible modules can be obtained for nonnegative integer $t$ depending on highest weight. Besides we obtained supercharcters of projective covers as specialisation of some nonsingular modification of super Jacobi polynomials.
Let $\mathcal{D}_{n,m}$ be the algebra of the quantum integrals of the deformed Calogero-Moser-Sutherland problem corresponding to the root system of the Lie superalgebra $\frak{gl}(n,m)$. The algebra $\mathcal{D}_{n,m}$ acts naturally on the quasi-invariant Laurent polynomials and we investigate the corresponding spectral decomposition. Even for general value of the parameter $k$ the spectral decomposition is not simple and we prove that the image of the algebra $\mathcal{D}_{n,m}$ in the algebra of endomorphisms of the generalised eigen-space is $k[\varepsilon]^{\otimes r}$ where $k[\varepsilon]$ is the algebra of the dual numbers the corresponding representation is the regular representation of the algebra $k[\varepsilon]^{\otimes r}$.
We study the orbits and polynomial invariants of certain affine action of the super Weyl groupoid of Lie superalgebra $\mathfrak {gl}(n,m)$, depending on a parameter. We show that for generic values of the parameter all the orbits are finite and separated by certain explicitly given invariants. We also describe explicitly the special set of parameters, for which the algebra of invariants is not finitely generated and does not separate the orbits, some of which are infinite.
The representation theory of symmetric Lie superalgebras and corresponding spherical functions are studied in relation with the theory of the deformed quantum Calogero-Moser systems. In the special case of symmetric pair g=gl(n,2m), k=osp(n,2m) we establish a natural bijection between projective covers of spherically typical irreducible g-modules and the finite dimensional generalised eigenspaces of the algebra of Calogero-Moser integrals D_{n,m} acting on the corresponding Laurent quasi-invariants A_{n,m}.
We develop the general theory of Jack-Laurent symmetric functions, which are certain generalisations of the Jack symmetric functions, depending on an additional parameter p_0.
We consider the Jack--Laurent symmetric functions for special values of parameters p_0=n+k^{-1}m, where k is not rational and m and n are natural numbers. In general, the coefficients of such functions may have poles at these values of p_0. The action of the corresponding algebra of quantum Calogero-Moser integrals D(k,p_0) on the space of Laurent symmetric functions defines the decomposition into generalised eigenspaces. We construct a basis in each generalised eigenspace as certain linear combinations of the Jack--Laurent symmetric functions, which are regular at p_0=n+k^{-1}m, and describe the action of D(k,p_0) in these eigenspaces.
We define the Dunkl and Dunkl-Heckman operators in infinite number of variables and use them to construct the quantum integrals of the Calogero-Moser-Sutherland problems at infinity. As a corollary we have a simple proof of integrability of the deformed quantum CMS systems related to classical Lie superalgebras. We show how this naturally leads to a quantum version of the Moser matrix, which in the deformed case was not known before.
For two different natural definitions of Casimir operators for simple Lie algebras we show that their eigenvalues in the adjoint representation can be expressed polynomially in the universal Vogel's parameters $α, β, γ$ and give explicit formulae for the generating functions of these eigenvalues.
The Grothendieck rings of finite dimensional representations of the basic classical Lie superalgebras are explicitly described in terms of the corresponding generalised root systems. We show that they can be interpreted as the subrings in the weight group rings invariant under the action of certain groupoids called Weyl groupoids.
We prove that Euler supercharacters for orthosymplectic Lie superalgebras can be obtained as a certain specialization of super Jacobi polynomials. A new version of Weyl type formula for super Schur functions and specialized super Jacobi polynomials play a key role in the proof.
Various infinite-dimensional versions of Calogero-Moser operator are discussed in relation with the theory of symmetric functions and representation theory of basic classical Lie superlagebras. This is a version of invited talk given by the second author at XVI International Congress on Mathematical Physics in Prague, August 2009.
Various infinite-dimensional versions of the Calogero-Moser operator are discussed. The related class of Jack-Laurent symmetric functions is studied. In the special case when parameter k=-1 the analogue of Jacobi-Trudy formula is given and the relation with representation theory of Lie superlagebra gl(m,n) is discussed.
An infinite-dimensional version of Calogero-Moser operator of $BC$-type and the corresponding Jacobi symmetric functions are introduced and studied, including the analogues of Pieri formula and Okounkov's binomial formula. We use this to describe all the ideals linearly generated by the Jacobi symmetric functions and show that the deformed $BC(m,n)$ Calogero-Moser operators, introduced in our earlier work, appear here in a natural way as the restrictions of the $BC_{\infty}$ operator to the corresponding finite-dimensional subvarieties. As a corollary we have the integrability of these quantum systems and all the main formulas for the related super Jacobi polynomials.