the error for computing MET with the momentum of visiable particles

[violin]

Dear experts,

I want to compute MET which is equal to the sum of all visiable particles transverse momentum. But in delphes MET is only based on the calorimetric cells. I don't know how to modify the card.dat.

I add InputArray InputArray in missing ET merger in delphes_card.dat.
###################
# Missing ET merger
###################

module Merger MissingET {
add InputArray InputArray
add InputArray EFlowMerger/eflow
set MomentumOutputArray momentum
}

But there are no events in delphes_card.lhco.

I used the MadGraph5_v1.5.11 with Delphes 3.0.9.

Thanks
Violin

[Michele Selvaggi]

Hi Violin,

just to clarify, if you run without modifying the card, do you still get an empty lhco file?

If yes, please tell us which list of commands you run so that we can reproduce your issue.
If not, could you please attach here your delphes card?

Thanks,

Michele

[violin]

Hi Michele,

If I ran without modifying the card, I can get a perfect lhco file. It workes well.

I have attached my delphes card.

Cheers,
Violin

[Michele Selvaggi]

I have attached a new card that should work.

[violin]

Hi,

The new card could be worked very well. But I have no idea what the MET is defined in this case.
Is it only the energy flow or the sum of all visiable particles transverse momentum?

Cheers,
Violin

[Michele Selvaggi]

Hi,

the energy flow collection is a combination of tracks and calorimeter towers, aimed at maximising the resolution.
It accounts for all the energy deposits in the detector acceptance.

What do you mean by "sum of all visible particles transverse momentum" ?

Michele

[violin]

Hi Michele,

I'm a new user. I couldn't understand MET very well. For example, I produced the process of z+photon with z decay to neutrino. But I found the transverse momentum distribution of photon was different from the distribution of MET. If I want to apply missing ET cut, I don't sure I should use MET or the transverse momentum of photon. I have no idea which one of them may be better.

Thanks
Violin

[Michele Selvaggi]

Hi Violin,

it is expected to have a slight difference in the MET and the pt of the photon, since you have also to account for the hadronic component (ISR in your case). Then, whether you want to use MET or the photon pt, really depends on what you are trying to achieve.

As it is, the MET vector gives minus the sum of deposited energy in the detector, that is, photon+ISR.

Is it more clear?

Michele

[violin]

Hi Michele,

I have understood it. Thank you very much!

Violin