019_first_steering_file.py

#!/usr/bin/env python3
 
import sys
import basf2 as b2
import modularAnalysis as ma
import stdV0s
import variables.collections as vc
import variables.utils as vu
 
# get input file number from the command line
filenumber = sys.argv[1]
 
# create path
main = b2.Path()
 
# load input data from mdst/udst file
ma.inputMdstList(
    filelist=[b2.find_file(f"starterkit/2021/1111540100_eph3_BGx0_{filenumber}.root", "examples")],
    path=main,
)
 
# fill final state particle lists
ma.fillParticleList(
    "e+:uncorrected",
    "electronID > 0.1 and dr < 0.5 and abs(dz) < 2 and thetaInCDCAcceptance",
    path=main,
)
stdV0s.stdKshorts(path=main)
 
# combine final state particles to form composite particles
ma.reconstructDecay(
    "J/psi:ee -> e+:uncorrected e-:uncorrected", cut="abs(dM) < 0.11", path=main
)
 
# combine J/psi and KS candidates to form B0 candidates
ma.reconstructDecay(
    "B0 -> J/psi:ee K_S0:merged",
    cut="Mbc > 5.2 and abs(deltaE) < 0.15",
    path=main,
)
 
# match reconstructed with MC particles
ma.matchMCTruth("B0", path=main)
 
# create list of variables to save into the output file
b_vars = []
 
standard_vars = vc.kinematics + vc.mc_kinematics + vc.mc_truth
b_vars += vc.deltae_mbc
b_vars += standard_vars
 
# variables for final states (electrons, positrons, pions) [S50]
fs_vars = vc.pid + vc.track + vc.track_hits + standard_vars
b_vars += vu.create_aliases_for_selected(
    fs_vars,
    "B0 -> [J/psi -> ^e+ ^e-] [K_S0 -> ^pi+ ^pi-]",
    prefix=["ep", "em", "pip", "pim"],
)  # [E50]
 
# variables for J/Psi, KS
jpsi_ks_vars = vc.inv_mass + standard_vars
b_vars += vu.create_aliases_for_selected(jpsi_ks_vars, "B0 -> ^J/psi ^K_S0")
 
# also add kinematic variables boosted to the center of mass frame (CMS) [S60]
# for all particles
cmskinematics = vu.create_aliases(
    vc.kinematics, "useCMSFrame({variable})", "CMS"
)  # [E60]
b_vars += vu.create_aliases_for_selected(
    cmskinematics, "^B0 -> [^J/psi -> ^e+ ^e-] [^K_S0 -> ^pi+ ^pi-]"
)
 
# save variables to an output file (ntuple)
ma.variablesToNtuple(
    "B0",
    variables=b_vars,
    filename="Bd2JpsiKS.root",
    treename="tree",
    path=main,
)
 
# start the event loop (actually start processing things)
b2.process(main)
 
# print out the summary
print(b2.statistics)