Rf 3 1 0_Sliceplot¶

Multidimensional models: projecting pdf and data slices in discrete observables

Author: Clemens Lange, Wouter Verkerke (C++ version)
This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Wednesday, January 19, 2022 at 10:19 AM.

In [ ]:
import ROOT

Create B decay pdf with mixing¶

Decay time observables

In [ ]:
dt = ROOT.RooRealVar("dt", "dt", -20, 20)

Discrete observables mixState (B0tag==B0reco?) and tagFlav (B0tag==B0(bar)?) Define state labels of discrete observables

In [ ]:
mixState = ROOT.RooCategory("mixState", "B0/B0bar mixing state", {"mixed": -1, "unmixed": 1})
tagFlav = ROOT.RooCategory("tagFlav", "Flavour of the tagged B0", {"B0": 1, "B0bar": -1})

Model parameters

In [ ]:
dm = ROOT.RooRealVar("dm", "delta m(B)", 0.472, 0.0, 1.0)
tau = ROOT.RooRealVar("tau", "B0 decay time", 1.547, 1.0, 2.0)
w = ROOT.RooRealVar("w", "Flavor Mistag rate", 0.03, 0.0, 1.0)
dw = ROOT.RooRealVar("dw", "Flavor Mistag rate difference between B0 and B0bar", 0.01)

Build a gaussian resolution model

In [ ]:
bias1 = ROOT.RooRealVar("bias1", "bias1", 0)
sigma1 = ROOT.RooRealVar("sigma1", "sigma1", 0.01)
gm1 = ROOT.RooGaussModel("gm1", "gauss model 1", dt, bias1, sigma1)

Construct a decay pdf, with single gaussian resolution model

In [ ]:
bmix_gm1 = ROOT.RooBMixDecay("bmix", "decay", dt, mixState, tagFlav, tau, dm, w, dw, gm1, type="DoubleSided")

Generate BMixing data with above set of event errors

In [ ]:
data = bmix_gm1.generate({dt, tagFlav, mixState}, 20000)

Plot full decay distribution¶

Create frame, data and pdf projection (integrated over tagFlav and mixState)

In [ ]:
frame = dt.frame(Title="Inclusive decay distribution")
data.plotOn(frame)
bmix_gm1.plotOn(frame)

Plot decay distribution for mixed and unmixed slice of mixState¶

Create frame, data (mixed only)

In [ ]:
frame2 = dt.frame(Title="Decay distribution of mixed events")
data.plotOn(frame2, Cut="mixState==mixState::mixed")

Position slice in mixState at "mixed" and plot slice of pdf in mixstate over data (integrated over tagFlav)

In [ ]:
bmix_gm1.plotOn(frame2, Slice=(mixState, "mixed"))

Create frame, data (unmixed only)

In [ ]:
frame3 = dt.frame(Title="Decay distribution of unmixed events")
data.plotOn(frame3, Cut="mixState==mixState::unmixed")

Position slice in mixState at "unmixed" and plot slice of pdf in mixstate over data (integrated over tagFlav)

In [ ]:
bmix_gm1.plotOn(frame3, Slice=(mixState, "unmixed"))

c = ROOT.TCanvas("rf310_sliceplot", "rf310_sliceplot", 1200, 400)
c.Divide(3)
c.cd(1)
frame.GetYaxis().SetTitleOffset(1.4)
frame.Draw()
c.cd(2)
frame2.GetYaxis().SetTitleOffset(1.4)
frame2.Draw()
c.cd(3)