Units used in Delphes

[F.Rojas-Abatte]

Do you know where I can find the units used by Delphes to show the information in the histograms? For example what units are used in Track.L leaf? (millimeters, micrometers)?
I couldn't find it.

[Pavel Demin]

Thanks for reporting this issue.

I've just added the information about the units to WorkBook/RootTreeDescription.

The momentum units are GeV, the position units are millimeters.

[F.Rojas-Abatte]

Dears:
I generated the following event in the MSSM model:

pp->~1+,~1-, jet
pp->~1+,~o1, jet
pp->~1-,~o1, jet

where ~1+,~1- = charginos, ~o1 = neutralino

When I plot the track path length (Track.L) it show that the charginos can travel several meters if the units are millimeters.
¿that can't be correct?

[Pavel Demin]

that can't be correct

Why not? I think that in your setup, the charginos are considered by Delphes as stable particles that are extrapolated to the calorimeter. In both ATLAS and CMS cards, the dimensions of the calorimeter are approximately 1*3 meters. So, I'd expect the values of Track.L to be between 1 and 3-4 meters.

[F.Rojas-Abatte]

Dears:

I check that the charginos in the previous example have Particle.Status=22, so this means that they should decay. I was trying to get the same number as the one in the Track.L class using the following way in a C file:

New_Track.L = sqrt(pow(Vertex_X[i]-Particle_X[i],2) + pow(Vertex_Y[i]-Particle_Y[i],2) + pow(Vertex_Z[i]-Particle_Z[i],2) - pow(Vertex_T[i]-Particle_T[i],2)*pow(c_vel,2));

where Vertex_(X,Y,Z,T) are the decay vertex position of the chargino, Particle_(X,Y,Z,T) are the production vertex position of the chargino and c_vel is the light velocity in cm. However y get different distributions. I'm new using Delphes so please excuse me if I'm making some silly mistake.
Thanks for the help.

[Pavel Demin]

If I'm not mistaken, Delphes creates tracks only for particles with status 1. I don't understand why you have a track corresponding to a particle with status 22. Please provide more details about your setup.

Here is a link to the code that calculates l:
​https://github.com/delphes/delphes/blob/master/modules/ParticlePropagator.cc#L368