Dear Rootians,

I am interested in computing the charge miss identification rates. These rates are derived from the data, based on the fraction of Z ->ee. The events in the m_ee region around the reconstructed Z-boson peak mZ are used.

For Nij electron pairs falling in the bin combination i,j the expected number of same-sign events is:

where ϵi and ϵj are the QMisID rates for each of the two electrons.

If all the same-sign events in the Z peak are produced by charge flip, then these numbers are described by a Poisson distribution:

Where observed events =>

and expected events =>

The probability for both electrons to produce a charge flip is:

Which is integrated into likelihood

that can be maximised (minimisation of -2lnL) to obtain the rates that best describe the data.

So for that, I have draw the distribution of Z->ee and apply the fit using the likelihood fit.

the fit results are as follows

```
****************************************
Minimizer is Minuit / Migrad
MinFCN = 272.163
Chi2 = 48.8082
NDf = 46
Edm = 7.15068e-008
NCalls = 91
p0 = 10345 +/- 425.092
p1 = 90.205 +/- 0.162891
p2 = 1.80446 +/- 0.374657
p3 = 3.82712 +/- 0.528939
```

What I did not understand is that …what will be the QmisID rates( ϵi,ϵj) form the likelihood fit results?

Many thanks