Belle II Software light-2406-ragdoll
B2A403-KFit-VertexFit.py
1#!/usr/bin/env python3
2
3
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30
31import basf2 as b2
32from modularAnalysis import inputMdst
33from modularAnalysis import reconstructDecay
34from modularAnalysis import matchMCTruth
35from vertex import kFit
36from stdCharged import stdPi, stdK
37from modularAnalysis import variablesToNtuple
38import variables.collections as vc
39import variables.utils as vu
40
41# create path
42my_path = b2.create_path()
43
44# load input ROOT file
45inputMdst(filename=b2.find_file('B02pi0D0_D2kpi_B2Dstarpi_Dstar2Dpi_D2kpi.root', 'examples', False),
46 path=my_path)
47
48
49# use standard final state particle lists
50#
51# creates "pi+:all" ParticleList (and c.c.)
52stdPi('all', path=my_path)
53# creates "pi+:loose" ParticleList (and c.c.)
54stdPi('loose', path=my_path)
55# creates "K+:loose" ParticleList (and c.c.)
56stdK('loose', path=my_path)
57
58# reconstruct D0 -> K- pi+ decay
59# keep only candidates with 1.8 < M(Kpi) < 1.9 GeV
60reconstructDecay('D0:kpi -> K-:loose pi+:loose', '1.8 < M < 1.9', path=my_path)
61
62# Perform D0 vertex fit.
63# Reject the candidates with failed fit.
64kFit('D0:kpi', 0.0, path=my_path)
65
66# reconstruct D*+ -> D0 pi+ decay
67# keep only candidates with Q = M(D0pi) - M(D0) - M(pi) < 20 MeV
68# and D* CMS momentum > 2.5 GeV
69reconstructDecay('D*+ -> D0:kpi pi+:all', '0.0 <= Q < 0.02 and 2.5 < useCMSFrame(p) < 5.5', path=my_path)
70
71# perform MC matching (MC truth association)
72matchMCTruth('D*+', path=my_path)
73
74# perform D*+ vertex fit
75# keep candidates only passing C.L. value of the fit > 0.0 (no cut)
76kFit('D*+', 0.0, path=my_path)
77
78# Select variables that we want to store to ntuple
79
80dstar_vars = vc.inv_mass + vc.mc_truth
81
82fs_hadron_vars = vu.create_aliases_for_selected(
83 vc.pid + vc.track + vc.mc_truth,
84 'D*+ -> [D0 -> ^K- ^pi+] ^pi+')
85
86d0_vars = vu.create_aliases_for_selected(
87 vc.inv_mass + vc.mc_truth,
88 'D*+ -> ^D0 pi+', 'D0')
89
90
91# Saving variables to ntuple
92output_file = 'B2A403-KFit-VertexFit.root'
93variablesToNtuple('D*+', dstar_vars + d0_vars + fs_hadron_vars,
94 filename=output_file, treename='dsttree', path=my_path)
95
96# Process the events
97b2.process(my_path)
98
99# print out the summary
100print(b2.statistics)