Understanding Interesting Isolation Variable Plot

Newbie
1

Hi everyone,
Me and my lab partner are doing an undergraduate lab using the 13 TeV ATLAS open dataset.

We have been using the monte carlo data for the Higgs decaying into 2 photons (all 4 production processes combined). We produce the following 2D histogram, with the etcone and ptcone variables for the highest transverse momentum photons on the x and y axis respectively, with MeV units:

|733px;x497px;

Note the empty region - does anybody know why this occurs? Are jets associated with Higgs production guaranteed to have high transverse energies/momenta? Is there reasoning for the diagonal boundaries of this region?

Here is real data, with a 2 photon selection cut applied, for comparison:

|469px;x318px;

Any insight is appreciated, even if that’s telling us a better place to ask this question :slight_smile:

Thanks,
Tom

2

See “Questions or comments?” in: ATLAS Experiment → Resources → ATLAS Open Data