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Hecke algebra representations of braid groups and classical Yang-Baxter equations. (English) Zbl 0667.17009

Conformal field theory and solvable lattice models, Symp., Kyoto/Jap. 1986, Adv. Stud. Pure Math. 16, 255-269 (1988).
[For the entire collection see Zbl 0646.00016.]
Motivated by the study of rational solutions of the classical Yang-Baxter equations due to A. A. Belavin and V. G. Drinfel’d [Funkts. Anal. Prilozh. 16, No.3, 1-29 (1982; Zbl 0504.22016)], a flat connection is constructed over \(X_ n=\{(z_ 1,...,z_ n)\in {\mathbb{C}}^ n\); \(z_ i\neq z_ j\) if \(i\neq j\}\), the fundamental group of which is the pure braid group on n strings. For a simple complex Lie algebra \({\mathfrak g}\) with Casimir element c and a set of n irreducible representations \(\rho_ i: {\mathfrak g}\to End(V_ i)\), one defines \(\Omega_{ij}\in End(V_ 1\otimes... \otimes V_ n)\) by \(\Omega_{ij}=(\rho_ i\otimes \rho_ j)(\Omega)\) where \(\Omega =(1/2)(\Delta c-c\otimes 1-1\otimes c)\in U({\mathfrak g})\otimes U({\mathfrak g}).\) Given a complex number \(\lambda\), a connection is then defined by \(\sum \lambda \Omega_{ij} d \log (z_ i-z_ j),\) the integrability of which follows from the infinitesimal pure braid relations. Thus the monodromy of the connection gives rise to a linear representation of the fundamental group of \(X_ n\), which becomes a linear representation of the braid group depending upon a parameter \(\lambda\) if all the representations \(\rho_ i\) are the same.
In a preceding paper of the author [Linear representations of braid groups and classical Yang-Baxter equations, Contemp. Math. 78, 339-363 (1988; Zbl 0661.20026)] the case of \({\mathfrak g}={\mathfrak sl}(2,{\mathbb{C}})\) and \(\rho_ i=the\) 2-dimensional irreducible representtion has been studied, giving rise to the Pimsner-\(Popa\)-\(Temperley\)-\(Lie\) representation. Here, the case \({\mathfrak g}={\mathfrak sl}(m+1,{\mathbb{C}})\) and \(\rho_ i=the\) \((m+1)\)- dimensional natural representation is considered. Hecke algebra representations of the braid group corresponding to Young diagrams of depth \(\leq m+1\) are obtained.
Reviewer: J.Van der Jeugt

MSC:

17B99 Lie algebras and Lie superalgebras
20G05 Representation theory for linear algebraic groups
35Q99 Partial differential equations of mathematical physics and other areas of application
17B20 Simple, semisimple, reductive (super)algebras
17B10 Representations of Lie algebras and Lie superalgebras, algebraic theory (weights)
20F36 Braid groups; Artin groups