@0celo7 I use @article {amrw17,
AUTHOR = {Pramod Achar and Shotaro Makisumi and Simon Riche and Geordie Williamson},
TITLE = {Koszul duality for Kac-Moody groups and characters of tilting modules},
JOURNAL = {arXiv:1706.00183 [math.RT]},
YEAR = {2017},
}