Positive Representations of Split Real Quantum Groups: The Universal R Operator

TL;DR

This paper computes the universal R operator for positive representations of split real quantum groups, introduces a C*-algebraic framework, and explores new functional relations of the quantum dilogarithm, advancing the understanding of quantum group structures.

Contribution

It generalizes known formulas for the universal R operator to split real quantum groups, introduces a C*-algebraic approach, and studies the quantum Weyl element and Lusztig's isomorphism in this setting.

Findings

Derived new functional relations of the quantum dilogarithm.

Provided a rigorous C*-algebraic formulation of split real quantum groups.

Extended the structure of the universal R operator and ribbon elements.

Abstract

The universal $R$ operator for the positive representations of split real quantum groups is computed, generalizing the formula of compact quantum groups $U_q(g)$ by Kirillov-Reshetikhin and Levendorski\u{\i}-Soibelman, and the formula in the case of $U_{q\tilde{q}}(sl(2,R))$ by Faddeev, Kashaev and Bytsko-Teschner. Several new functional relations of the quantum dilogarithm are obtained, generalizing the quantum exponential relations and the pentagon relations. The quantum Weyl element and Lusztig's isomorphism in the positive setting are also studied in detail. Finally we introduce a $C^*$-algebraic version of the split real quantum group in the language of multiplier Hopf algebras, and consequently the definition of $R$ is made rigorous as the canonical element of the Drinfeld's double $\textbf{U}$ of certain multiplier Hopf algebra $\textbf{Ub}$. Moreover a ribbon structure is introduced for an extension of $\textbf{U}$.