Cross section

[bdrum]

Now I have number of events with $\rho'$ for each runs and I can get luminosity of these runs.

This means that I can get cross section of the $\rho'$

In fact this is not true, but why?

$$\sigma=\frac{N}{L}$$

Obviously this should be flat. But for such definition I can't confirm that:

Actually in case we will take std as $\frac{1}{\sqrt{nev}}$ such calculation looks strange because of scale doesn't match.

Perhaps, we have to normalize the data. In this case we can see flat curve(last picture):

[bdrum]

Actually in case we will take std as $\frac{1}{\sqrt{nev}}$ such calculation looks strange because of scale doesn't match.

For sure it is not correct. Here we have typical Poisson distribution (large numbers of events and small probability) i.e. $\lambda=np$, but $p=\frac{n_g}{n}$ and this means that $\sigma=n_g$

Perhaps, we have to normalize the data. In this case we can see flat curve(last picture)

Also we shouldn't normalize this data but we have to change luminosity scale. I multiply all luminosities by 1000: