e2tau.py

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# Copyright (C) 2002-2023 CERN for the benefit of the ATLAS collaboration
 
from AthenaCommon import Logging
from ...decorators import timed
from ...utility import LHE
import shutil
 
 
logger = Logging.logging.getLogger("PowhegControl")
 
 
@timed("e2tau")
def e2tau(powheg_LHE_output):
    """! Post-process existing events from electrons to taus
 
    @param powheg_LHE_output  Name of LHE file produced by PowhegBox.
 
    @author Jan Kretzschmar <jan.kretzschmar@cern.ch>
    """
    logger.warning("Converting LHE events from electron to tau decays. Tau mass must be restored by showering program, ensure to validate physics.")
 
    # Get opening and closing strings
    preamble = LHE.preamble(powheg_LHE_output)
    postamble = LHE.postamble(powheg_LHE_output)
    
    n_events = 0
    powheg_LHE_tau = "{}.tau".format(powheg_LHE_output)
    with open(powheg_LHE_tau, "w") as f_output:
        f_output.write("{}\n".format(preamble))
        for input_event in LHE.event_iterator(powheg_LHE_output):
            is_event_changed, output_event = LHE.e2tau(input_event)
            f_output.write(output_event)
            n_events += [0, 1][is_event_changed]
        f_output.write(postamble)
    logger.info("Changed mu->tau in {} events!".format(n_events))
 
    # Make a backup of the original events
    shutil.move(powheg_LHE_output, "{}.e2tau_backup".format(powheg_LHE_output))
    shutil.move(powheg_LHE_tau, powheg_LHE_output)