Fixed condition inverted
Update chi^2 references values, computed with new selection & powheg sample
Use optimal chi^2 configuration

See https://docs.google.com/spreadsheet/ccc?key=0AsI4zLOlSqcUdFRsWXdKYjhyOVBsSGJvX3FuNjl6RWc&usp=sharing
for detailled numbers
Use TClonesArray instead of storing directly TLorentzVector