%0 Journal Article %A Julien Marché %A Maxime Wolff %T The parallelogram identity on groups and deformations of the trivial character in $\protect \mathrm{SL}_2(\protect \mathbb{C})$ %J Journal de l’École polytechnique — Mathématiques %D 2020 %P 263-285 %V 7 %I École polytechnique %U https://jep.centre-mersenne.org/articles/10.5802/jep.117/ %R 10.5802/jep.117 %G en %F JEP_2020__7__263_0