Hello @ajaydeo,
thanks for following up and sorry for the late reply!
The problem with your fit is that the model is not appropriate for your data, at least with how the exponential is defined in RooFit. A RooExponential has no boundaries, so it is increasing to the left forever. This can’t fit your data.
Another RooFit user worked around this by multiplying the exponential with a step function before the convolution:
I have adapted your script to do this too, and also improved the parameter boundaries a bit. The fit now looks like this:
gexp_conv.C (3.0 KB)
Looks already a bit better! But still doesn’t fit perfectly. Maybe you need to include a second Gaussian.
Hope this helps!
Jonas