MC readers reset particle masses to PDG values

[Peter Onyisi]

Hi:

In Delphes 3.0.9 I find that the LHEF, STDHEP, and HepMC readers all have code of this form

candidate->Mass = pdgParticle ? pdgParticle->Mass() : -999.9;

which sets the particle mass to the PDG mass, regardless of what the generator produces. Especially for off-shell Z and W, this means that we have to reconstruct the W and Z mass through daughter kinematics. Is there a reason not to use the mass from the event record?

Thanks,
Peter

[Pavel Demin]

Hi Peter,

As far as I know, there is no reason to use the PDG mass.

I've modified all the readers to use the mass from the event record.

Here is a preliminary version:

​​http://cp3.irmp.ucl.ac.be/downloads/Delphes-3.0.10.pre8.tar.gz

Could you, please check if this version works better?

Regards,

Pavel

[Pavel Demin]

New readers that read masses from the MC event files are available in the new release 3.0.10.