NNLO vs parton-showers - THEP Mainz

Higgs p T spectrum• we know that if we integrate the fixed-order cross-section overa large enough region the effects of multiple soft and collinearradiation become negligible... But how ‘large’?• we compare the cumulative cross-section in p TH...• ... at NLO:• NLO+NLL and MC@NLOagree very well• need to integrate the fixedorderNLO spectrum up toabout 50 GeV to get a closeresult• NLO prediction will fail whenrestricting to smallerregions!22