def process(self, event):
     pivot = getattr(event, self.cfg_ana.pivot)[0]
     ptcs = getattr(event, self.cfg_ana.particles)
     dR = self.cfg_ana.dR
     cone_ptcs = inConeCollection(pivot, ptcs, dR, 0.)
     for ptc in cone_ptcs:
         setattr(ptc, 'dR', deltaR(pivot, ptc))
     tlv = TLorentzVector(pivot.p4())
     tlv.SetPhi(pivot.p4().Phi() + math.pi)
     tlv_theta = math.pi - pivot.p4().Theta()
     if tlv_theta >= math.pi:
         tlv_theta -= math.pi
     tlv.SetTheta(tlv_theta)
     control_pivot = Particle(pivot.pdgid(), pivot.charge(), tlv)
     control_cone_ptcs = inConeCollection(control_pivot, ptcs, dR, 0.)
     setattr(event, self.cfg_ana.output, cone_ptcs)
     setattr(event, self.cfg_ana.control_output, control_cone_ptcs)