Post decay search operations

Further annotations

Required input

Following the decay search, a root file with decay search information should have been produced. Each entry of this tree correspond to a primary vertex , and there are vectors for associated secondary vertices and their tracks.

The script

https://github.com/antonioiuliano2/macros-ship/blob/master/analisi_charmsim/selection_decaysearch_sim.C

will add new branches, with further variables and boolean checks.

Provided new variables

The new computed variables (that is, no simple booleans) are the following ones:

• vtx_mc_ev : MCEventID of the primary vertex. Computed as the most common MCEventID of its tracks;

• dsvtx_vtx2_dl: Decay length of charm candidate. Computed as the 3D distance between the points of primary and secondary vertices;

• dsvtx_vtx2_tau: Approximated estimated mean life of charm candidate. Computed from average kink angle and impact parameter of daughter track to primary vertex;

• dsvtx_vtx_phicharm: Phi angle of candidate charmed hadron. Computed from the positions of primary and secondary vertices

• dsvtx_vtx2_endingdeltaphi: Angular difference between a tracked charm candidate and its estimation. Computed from the angles of a reconstructed track linking primary and secondary vertex. If no such track exists, return -10, if more than one exist, return 10

• dsvtx_vtx2_meanphi: Average phi angle of charm daughter candidates. Computed from the angles of tracks starting at the secondary vertex.

• dsvtx_vtx2_phidifference: Difference of the aforementioned average mean phi angle and the estimated phi angle of charmed hadron candidate.

Provided checks

Additional boolean variables are provided, to select events according to the following criteria

• vtx_2starting: The primary vertex contains at least two tracks starting from it;

• vtx_2goodtrks: The primary vertex contains at least two tracks with at least 3 segments;

• dsvtx_vtx2_2starting: The secondary vertex contains at least two tracks starting from it

• dsvtx_vtx2_2starting_trk: The track belongs to a secondary vertex which satifies the previous condition

• dsvtx_vtx2_2goodtrks: The secondary vertex contains at least two tracks with at least 3 segments

• dsvtx_vtx2_2goodtrks_trk: The track belongs to a secondary vertex which satifies the previous condition

• dsvtx_vtx2_trk_charmdaughter: The track is a charm daughter (MCMotherID 1 or 2)

• dsvtx_vtx2_charmdaughter: The vertex contains at least one charm daughter (see previous condition);

• dsvtx_vtx2_trk_samevent: The track is from the same MCEvent of the primary vertex;

• dsvtx_vtx2_samevent: the secondary vertex contains at least one track from the same MCEventID of the primary vertex (see previous condition)

• dsvtx_vtx2_charmdaughtersamevent: The secondary vertex contains at least one charm daughter, which is also from the same MCEventID of the primary vertex (it practically combines, for the same track, the previous conditions)

• dsvtx_vtx2_positivedz: The difference between z position of secondary and primary vertex is larger than 0 (i.e. secondary vertex is downstream of the primary one)

• dsvtx_vtx2_trk_positivedz: The track belongs to a secondary vertex which satifies the previous condition

Finally, a good secondary vertex is estimated by requiring positive dz and at least one charmdaughter from the same MC event. This provides the last variable:

• vtx_topology: 1 for single charm, 2 for double charm, 0 otherwise.