Modular quantum dilogarithm

introduction

• introduced by Ludvig Faddeev
• called the modular quantum dilogarithm or regularized quantum dilogarithm
• applications
  • S-matrix of the quantum sine-Gordon model
• definition : $b\in \mathbb{C}$ with non-zero real part and $z\in \mathbb{C}$

$$ \Phi_{b}(z)=\exp\left(-\frac{1}{4}\int \frac{e^{-2zx\sqrt{-1}}}{\sinh(xb) \sinh(x/b)}\, \frac{dx}{x}\right) $$

articles

• Johnson, P. R. 1996. “Exact Quantum S-matrices for Solitons in Simply-laced Affine Toda Field Theories.” arXiv:hep-th/9611117 (November 15). doi:10.1016/S0550-3213(97)00239-3. http://arxiv.org/abs/hep-th/9611117.
• Faddeev, L. 1995. “Discrete Heisenberg-Weyl Group and Modular Group.” arXiv:hep-th/9504111 (April 21). doi:10.1007/BF01872779. http://arxiv.org/abs/hep-th/9504111.
• Faddeev, L. D. 1994. “Current-Like Variables in Massive and Massless Integrable Models.” arXiv:hep-th/9408041 (August 7). http://arxiv.org/abs/hep-th/9408041.