B2A301-Dstar2D0Pi-Reconstruction.py

#!/usr/bin/env python3
 
 
 
 
 
import basf2 as b2
import modularAnalysis as ma
import variables.collections as vc
import variables.utils as vu
import stdCharged as stdc
 
# create path
my_path = b2.create_path()
 
# load input ROOT file
ma.inputMdst(filename=b2.find_file('Dst2D0pi.root', 'examples', False),
             path=my_path)
 
 
# use standard final state particle lists
#
# creates "pi+:all" ParticleList (and c.c.)
stdc.stdPi(listtype='all', path=my_path)
# creates "pi+:loose" ParticleList (and c.c.)
stdc.stdPi(listtype='loose', path=my_path)
# creates "K+:loose" ParticleList (and c.c.)
stdc.stdK(listtype='loose', path=my_path)
 
# reconstruct D0 -> K- pi+ decay
# keep only candidates with 1.8 < M(Kpi) < 1.9 GeV
ma.reconstructDecay(decayString='D0:kpi -> K-:loose pi+:loose', cut='1.8 < M < 1.9', path=my_path)
 
# reconstruct D*+ -> D0 pi+ decay
# keep only candidates with Q = M(D0pi) - M(D0) - M(pi) < 20 MeV
ma.reconstructDecay(decayString='D*+ -> D0:kpi pi+:all', cut='0.0 < Q < 0.2', path=my_path)
 
# perform MC matching (MC truth association)
ma.matchMCTruth(list_name='D*+', path=my_path)
 
# Select variables that we want to store to ntuple
dstar_vars = vc.inv_mass + vc.mc_truth
 
# We now want to select variables for all of the final state hadrons in the
# decay products, that is, the K- and the two pi+.
# You already know how to define these variables with the help of the
# ``daughter`` metavariable: If we consider D^* -> D0 pi+, then we could access
# information about the pion as daughter(1, variable).
# Creating aliases for all of these variables would fill the next 100 lines
# though, so we instead use the ``create_aliases_for_selected`` helper function:
# We specify a list of variables and then a decay string, with particles
# selected with a leading ``^``.
# Again, for more information on how to create aliases, head over to
# VariableManager/variableAliases.py.
fs_hadron_vars = vu.create_aliases_for_selected(
    list_of_variables=vc.pid + vc.track + vc.mc_truth,
    decay_string='D*+ -> [D0 -> ^K- ^pi+] ^pi+')
 
d0_vars = vu.create_aliases_for_selected(
    list_of_variables=vc.inv_mass + vc.mc_truth,
    decay_string='D*+ -> ^D0 pi+',
    prefix='D0')
 
 
# Saving variables to ntuple
output_file = 'B2A301-Dstar2D0Pi-Reconstruction.root'
ma.variablesToNtuple('D*+', dstar_vars + d0_vars + fs_hadron_vars,
                     filename=output_file, treename='dsttree', path=my_path)
 
# Process the events
b2.process(my_path)
 
# print out the summary
print(b2.statistics)