%0 Journal Article %A L. Singhal %T Diophantine exponents for standard linear actions of ${\rm SL}_2$ over discrete rings in $\mathbb {C}$ %J Acta Arithmetica %D 2017 %P 53-73 %V 177 %N 1 %I mathdoc %U http://geodesic.mathdoc.fr/articles/10.4064/aa8370-6-2016/ %R 10.4064/aa8370-6-2016 %G en %F 10_4064_aa8370_6_2016