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rf513_wsfactory_tools.py
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1 ## \file
2 ## \ingroup tutorial_roofit
3 ## \notebook -nodraw
4 ## Organization and simultaneous fits: illustration use of ROOT.RooCustomizer and
5 ## ROOT.RooSimWSTool interface in factory workspace tool in a complex standalone B physics example
6 ##
7 ## \macro_code
8 ##
9 ## \date February 2018
10 ## \authors Clemens Lange, Wouter Verkerke (C++ version)
11 
12 import ROOT
13 
14 
15 w = ROOT.RooWorkspace("w")
16 
17 # Build a complex example pdf
18 # -----------------------------------------------------------
19 
20 # Make signal model for CPV: A bmixing decay function in t (convoluted with a triple Gaussian resolution model)
21 # times a Gaussian function the reconstructed mass
22 w.factory(
23  "PROD::sig( BMixDecay::sig_t( dt[-20,20], mixState[mixed=1,unmix=-1], tagFlav[B0=1,B0bar=-1], "
24  "tau[1.54], dm[0.472], w[0.05], dw[0], "
25  "AddModel::gm({GaussModel(dt,biasC[-10,10],sigmaC[0.1,3],dterr[0.01,0.2]), "
26  "GaussModel(dt,0,sigmaT[3,10]), "
27  "GaussModel(dt,0,20)},{fracC[0,1],fracT[0,1]}), "
28  "DoubleSided ), "
29  "Gaussian::sig_m( mes[5.20,5.30], mB0[5.20,5.30], sigmB0[0.01,0.05] ))")
30 
31 # Make background component: A plain decay function in t times an Argus
32 # function in the reconstructed mass
33 w.factory("PROD::bkg( Decay::bkg_t( dt, tau, gm, DoubleSided), "
34  "ArgusBG::bkg_m( mes, 5.291, k[-100,-10]))")
35 
36 # Make composite model from the signal and background component
37 w.factory("SUM::model( Nsig[5000,0,10000]*sig, NBkg[500,0,10000]*bkg )")
38 
39 # Example of RooSimWSTool interface
40 # ------------------------------------------------------------------
41 
42 # Introduce a flavour tagging category tagCat as observable with 4 states corresponding
43 # to 4 flavour tagging techniques with different performance that require different
44 # parameterizations of the fit model
45 #
46 # ROOT.RooSimWSTool operation:
47 # - Make 4 clones of model (for each tagCat) state, will gain an individual
48 # copy of parameters w, and biasC. The other parameters remain common
49 # - Make a simultaneous pdf of the 4 clones assigning each to the appropriate
50 # state of the tagCat index category
51 
52 # ROOT.RooSimWSTool is interfaced as meta-type SIMCLONE in the factory. The $SplitParam()
53 # argument maps to the SplitParam() named argument in the
54 # ROOT.RooSimWSTool constructor
55 w.factory(
56  "SIMCLONE::model_sim( model, $SplitParam({w,dw,biasC},tagCat[Lep,Kao,NT1,NT2]))")
57 
58 # Example of RooCustomizer interface
59 # -------------------------------------------------------------------
60 #
61 # Class ROOT.RooCustomizer makes clones of existing pdfs with certain prescribed
62 # modifications (branch of leaf node replacements)
63 #
64 # Here we take our model (the original before ROOT.RooSimWSTool modifications)
65 # and request that the parameter w (the mistag rate) is replaced with
66 # an expression-based function that calculates w in terms of the Dilution
67 # parameter D that is defined D = 1-2*w
68 
69 # Make a clone model_D of original 'model' replacing 'w' with
70 # 'expr('0.5-D/2',D[0,1])'
71 w.factory("EDIT::model_D(model, w=expr('0.5-D/2',D[0,1]) )")
72 
73 # Print workspace contents
74 w.Print()
75 
76 # Make workspace visible on command line
77 ROOT.gDirectory.Add(w)