Using RooUnBlindPrecision

[amroo]

Hello RooFit experts,

I am trying to do a fit by blinding a fit parameter (tau see code snippet)
Here is what I want to achieve:

• Say the parameter to blind is tau, I want the Roofit to use tau for likelihood construction
• But the result printed by Roofit should have blinded parameter tau_blind which is randomly shifted from real tau by ± 5*sigma (sigma is some number)

I tried using RooUnblindPrecision following several posts in this forum
Below is the relevant code snippet I have used:

RooRealVar tau("tau","tau",0.000104,0,0.001);
                                                                                              
RooUnblindPrecision tau_blind("tau_blind","tau_blind","taublinded",0.000504,0.000004,tau,0);
                                                                                             
RooDecay decay("decay","lifetime",t,tau_blind,gauss1,RooDecay::SingleSided); 

According to available documentation, the arguments are:

RooUnblindPrecision name(“name”,“title”,“blindstring”,central value,scale,blindvalue,sin2betaMode);

But I don’t understand the meaning of these parameters
central value: ?
scale: ?
blind value: parameter to be blinded
sin2betaMode: ?

Can anyone please explain?
Or any other way of implementing what I am trying to do here in Roofit
other related function I came across RooUnblindUniform
Thanks

Related previous posts:

RooWorkspace and RooUnblindPrecision

I am trying to define a RooWorkspace including a blind variable inside using RooUnblindPrecision. The model is very simple: a gaussian over a 2nd order polynomial and is described in void makeModel(RooWorkspace &w) { RooRealVar mD("mD","m(D)",1.82,1.92); // Sig Gau RooRealVar m("m","mean D+",mDp_pdg,mDp_pdg-0.02,mDp_pdg+0.02,"GeV/c^{2}"); RooRealVar s("s","sigma D+",0.004,0.001,0.01,"GeV/c^{2}"); RooGaussian g("g","gaussian D+",mD,m,s); // poly Bkg RooRealVar p0("p0","poly0",.29…

RooBlindTools - questions, documentation and examples

Hi, I am using RooUnblindUniform and RooUnblindPrecision to blind some physics parameters I would like to measure. Except for the classes description and few presentations that mention the RooBlindTools, the documentation is poor. Could you please add a couple of examples in your tutorial ? In particular I have doubts on the possibility to limit the original parameters and the possibility to combine the unblinded ones in a rooformula var. as an example, I write below the code I am using RooRe…

[Axel]

Hi @amroo - I have invited @moneta and @jonas to help, but due to the Christmas break this might take a bit longer than we’d hope.

[moneta]

Hi,
Unfortunately we are missing a tutorial in Roofit for using these unblind tools.
I think the RooUnblindPrecision applies a simple transformation to the parameter mantaining the same fit precision. It is simply applying a translation defined by the scale around a given central value. See the corresponding code in
https://root.cern.ch/doc/master/RooBlindTools_8cxx_source.html#l00212

Cheers

Lorenzo