#!/usr/bin/env python
# coding: utf-8

# # How To: Compute NLL cross sections for a given SLHA file

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# Set up the path to SModelS installation folder
import sys; sys.path.append("."); import importlib; importlib.import_module("smodels_paths") if importlib.util.find_spec("smodels_paths") else None


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# Import those parts of smodels that are needed for this exercise
from smodels.tools import xsecComputer
from smodels.base.physicsUnits import TeV, fb
from smodels.installation import installDirectory
from smodels.tools.xsecComputer import LO, NLL


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# Define the SLHA file name
filename="inputFiles/slha/gluino_squarks.slha"


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# Lets compute the NLL cross-sections for 8 TeV. The xsecComputer will first use Pythia to compute
# the LO cross-sections and then NLLfast to compute the k-factors.
# The output will contain only the processes contained in NLLfast (gluino and squark production)
# For the Pythia step we have to define the number of MC events (1k)
# (To see how to also include LO cross-sections for all processes check the LO HowTo)
computer = xsecComputer.XSecComputer ( maxOrder=NLL, nevents = 100, pythiaVersion=8 )
xsecsNLL=computer.compute(sqrts = 8*TeV, slhafile=filename )


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# the output is a XSectionList ...
type(xsecsNLL)


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# Each entry in the list contains the cross-section value:
print(xsecsNLL[0].value)
# The PDGs of the particles produced:
print(xsecsNLL[0].pid)
# And some additional info
print("label =",xsecsNLL[0].info.label,"Sqrts =",xsecsNLL[0].info.sqrts, "QCD order =",xsecsNLL[0].info.order)


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# Finally, lets write the cross-sections back to the file 
# (will write only the cross-sections not overlapping the existing ones):
computer.addXSecToFile(xsecsNLL,filename)


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