  The next-to-leading order (NLO) corrections to Drell-Yan slepton pair
production are merged with parton shower evolution via the POWHEG method in
Herwig++. The NLO corrections at the level of event generation alter the shape
of observables in a non-global way, thereby potentially affecting the fraction
of signal events which pass crucial transverse momentum cuts on decay products
and missing transverse momentum requirements on events. This effect is not
captured by an overall rescaling of the cross section and can have
repercussions on the reach of LHC searches.
