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Opened 10 years ago

Closed 10 years ago

#330 closed Bug (fixed)

Delphes 3.1.2 not storing Track Dxy

Reported by: rob Owned by: Pavel Demin <pavel.demin@…>
Priority: major Milestone:
Component: Delphes code Version: Delphes 3
Keywords: Track Dxy Cc:

Description

Hi,

I ran Delphes 3.1.2 over a HEPMC file produced with Pythia8, using the example delphes_card_CMS.tcl. Looking at the output ROOT file, whilst the Track collection has data members Xd, Yd, Zd populated, Dxy is always set to 0 (while Xd and Yd are non-zero).

I had a look at the file classes/ParticlePropagator.cc, in the function ParticlePropagator::Process(). Dxy is calculated for the track:

// calculate impact paramater
ang_mom = (xd*py - yd*px);
dxy = ang_mom/pt;

but further on, it is not stored:

candidate->Momentum = candidateMomentum;
candidate->Xd = xd*1.0E3; 
candidate->Yd = yd*1.0E3;
candidate->Zd = zd*1.0E3;
candidate->AddCandidate(mother);

It looks like candidate->Dxy should be set there as well?

Thanks

Change History (3)

comment:1 by rob, 10 years ago

Sorry, meant modules/ParticlePropagator.cc, not classes/ParticlePropagator.cc

comment:2 by Michele Selvaggi, 10 years ago

Hi Rob,

if I remember correctly the original idea was to store, at the particle propagator level, only the information that was needed to calculate the impact parameter (x_d, y_d, p_x, p_y) and probably the part

// calculate impact paramater
ang_mom = (xd*py - yd*px);
dxy = ang_mom/pt;

is simply a left over. Instead the impact parameter was meant to be calculated when the module ImpactParameterSmearing is called.
Therefore if one needs no smearing (MC truth d_xy) then simply put

ResolutionFormula 0.0

when calling ImpactParameterSmearing.
If you need an example on how to call such module please have a look at the "delphes_card_FCC_basic.tcl"

This said, we will probably follow your advice at store by default the Dxy, SDxy value as computed by the ParticlePropagator.

Thanks,
Michele

Last edited 10 years ago by Michele Selvaggi (previous) (diff)

comment:3 by Pavel Demin <pavel.demin@…>, 10 years ago

Owner: set to Pavel Demin <pavel.demin@…>
Resolution: fixed
Status: newclosed
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