1. Event selection

p+p: there has to be at least 2 pions per event

Vertex cut: |v_z|<= 30 cm

2. Particle selection

bool good = track &&  
( track->flag() > 0 ) &&
( track->pt() > 0.1 ) &&
( track->pt() < 1.0 ) &&
( fabs(track->nSigmaPion()) <= 2.0 )  &&
( fabs(track->nSigmaKaon()) > 2.0 )   &&
( fabs(track->nSigmaProton()) > 2.0 )   && 
( fabs(track->nSigmaElectron()) > 2.0 )   &&
( track->topologyMap().numberOfHits(kTpcId) >= 10 ) && ( track->dca().perp() < 3.0 );