The present paper deals with the representation theory of the reflection equation algebra, connected with a Hecke type R-matrix. Up to some reasonable additional conditions the Rmatrix is arbitrary (not necessary originated from quantum groups). We suggest a universal method of constructing finite dimensional irreducible non-commutative representations in the framework of the Weyl approach well known in the representation theory of classical Lie groups and algebras. With this method a series of irreducible modules is constructed which are parametrized by Young diagrams. The spectrum of central elements s k = T r q L k is calculated in the single-row and single-column representations. A rule for the decomposition of the tensor product of modules into the direct sum of irreducible components is also suggested.
Reflection Equation AlgebraReflection equation and the corresponding algebra which will be called the reflection equation algebra (REA for short) play a significant role in the theory of integrable systems and non-commutative geometry. In application to integrable systems the reflection equation with a spectral parameter is mainly used. First it appears in the work by I. Cherednik [1]. Usually it comprises the information about the behaviour of a system at a boundary, for example, describes the reflection of particles on a boundary of the configuration space.The reflection equation without a spectral parameter is important for the non-commutative geometry. One of the first applications the corresponding REA found in the theory of differential calculus on quantum groups (see, e.g., [2]). In such a differential calculus REA with the Hecke type R-matrix is a non-commutative analog of the algebra of vector fields on the groups GL(N ) or SL(N ). Besides, REA serves as a base for a definition of quantum analogs of homogeneous spaces -orbits of the coadjoint representation of a Lie group, as well as quantum analogs of linear bundles over such orbits (see, e.g., [3, 4]).In this paper we turn to problems of the representation theory of REA without a spectral parameter. We are interested in the following main topics:i) a construction of finite dimensional non-commutative irreducible representations and the calculation of spectrum (characters) of central elements in these representations;ii) a rule for the decomposition of the tensor product of irreducible modules into irreducible components. * saponov@mx.ihep.su 1 Before reviewing the known results, we introduce some necessary definitions and notations. Consider an associative algebra L q with the unity e L over the complex field C generated by n 2 elementsl j i , 1 ≤ i, j ≤ n, n being a fixed positive integer. Let the generators satisfy the following quadratic commutation relationswhere the matrixL ∈ Mat n (L q ) is composed ofl j i :L = l j i . Here the lower index enumerates the rows while the upper one columns. In (1.1) and everywhere below the use is made of the compact matrix notations [5] when the index of an object indicates the vector space to which t...