Problem with TCuts

ROOT
1

Hi,

I’m using TCuts for my analysis - my intention is to plot the MissingEt for like-sign same-flavour lepton pairs.
The histogram with cut e3 has less entries than the same with cut c3.
Is there a mistake in the code ?

TCut c1 = "Mu_N==2";
TCut c2 = "(Mu_charge[0]==Mu_charge[1])";
TCut c3 = (c1 && c2);

TCut d1 = "El_N==2";
TCut d2 = "(El_charge[0]==El_charge[1])";
TCut d3 = (d1 && d2);

TCut e3 = c3 || d3;

mychain->Draw("MissingEt", e3);

Thank you,
Chris

2

Could you post a short (but running) script and a small data file reproducing the problem?
I am suspecting a problem with your cuts of style “a==b”.
If a and b are floating point variables, you should make the test including some numerical precision.

Rene

3

These are the files (thanks again):
analyse_roottalk.c (459 Bytes)
5200_Truth_isol_500.AAN.root (1.94 MB)

4

I can reproduce the problem. We are investigating.

Rene

5

Hi,

What you see is the (unfortunate) expected behavior. With the current code, if one of the element of the expression can not be evaluated (For example if El_N[0] does not exist because El_n.size()==0), the whole expression is invalidated. We have not yet found a good way (aka performant and clear enough) to prevent this.

However you have a simple work-around:

where you use the TTree::Draw special function Alt$ to express what should be the value of the expression in the case the values are missing).

Cheers,
Philippe.

6

Hi,

Independently, I noticed that with your file the value of El_N and the size of the corresponding vectors (like El_charge) are not consistent. For example, see the result of:mychain->Scan("El_N:El_charge@.size()");
Is this intentional?

Cheers,
Philippe

7

Thank you very much for your help!

Chris