Published online by Cambridge University Press: 20 November 2018
Let $K$ be a complex quadratic extension of
$\mathbb{Q}$ and let
${{\mathbb{A}}_{K}}$ denote the adeles of
$K$. We find special values at all of the critical points of twisted tensor
$L$-functions attached to cohomological cuspforms on
$G{{L}_{2}}\left( {{\mathbb{A}}_{K}} \right)$ and establish Galois equivariance of the values. To investigate the values, we determine the archimedean factors of a class of integral representations of these
$L$-functions, thus proving a conjecture due to Ghate. We also investigate analytic properties of these
$L$-functions, such as their functional equations.