For Bs -> J/psi Phi

1. Track selection of J/psi candidate:

- From jpsi Finder (this essentially does the same think that the skimming selection)

2. Jet clustering:

- Durham algorithm using pyclus subroutine from PYTHIA
- clustering parameter (PARU(45)) = 15 GeV;

3. J/psi selection:

- pt > 3 GeV
- 2.8 < Mass Jpsi< 3.35   


For Phi selection:

 - 2 tracks of opposite charge;
 - pt > 0.4 GeV of each track;
 - Both track have al least 2 measurement in the SMT; 
 - If any of the two tracks have pt< 0.7 : 
           - Pt Phi > 0.8  
            - For the Track with pt<0.7 (impact(axial)/sigma)2 + (impact(stereo)/sigma)2 > 1 ,
              here impact is the impact of the track to the primary vertex;
 - phi mass from 1.01 to 1.032 GeV
 
4. Bs->J/psi Phi candidate selection:

 - at least 2 particles have measurements in SMT;
 - Chi2 of Bs vertex < 32.;
 - l/sigma(l) > 3 , where l is the distance in xy between primary and the Bs vertex;
 - (impact(axial)/sigma)2 + (impact(stereo)/sigma)2 < 36,
   here impact is the impact of Bd track to the primary vertex;
 - cos(alpha) > 0.95, where alpha is the angle between B+ momentum
   and the direction from primary to secondary vertex;
 - if momentum of K+ or pi- < 0.7 Gev:
              - Chi2 of Bd vertex < 7.;
              - l/sigma(l) > 4.5 , 
 - J/psi mass constraint