dN/dx

Hi

I’m searching on the root manuel if there is a simple way to do differential plots on root. for example dsigma/dtheta for example.

Is there any way?

Thx. c.

To do a differential plot is just a normalisation technique really.

So to plots theta from tree t

t->Draw("theta>>h");
and to plot dsigma/dtheta:

h->Scale(norm)
where norm will be your normalisation factor which is normally the cross-section (x branching ratio) divided by the total number of events.

e.g.

Say I work out a cross section (145pb) and branching fraction (0.13) with pythia, then I use the detector software to make 1000 events and 360 are reconstructible after various cuts and detector limitations

sigma=145
bf=0.13
N=1000

draw and stick in histo h:

t->Draw("theta>>h", "(cut1<10)") h->Scale((sigma*bf/N)) h->GetYaxis()->SetTitle("dsigma/dtheta") h->GetXaxis()->SetTitle("theta (rad)") h->Draw();