Understanding PT/Energy resolution formula in Delphes Card

[Michael Albergo]

Hi there,

I am trying to make sense of the energy resolution in an example Delphes Card as defined below

###################################
# Momentum resolution for electrons
###################################

module MomentumSmearing ElectronMomentumSmearing {

set InputArray ElectronTrackingEfficiency/electrons
set OutputArray electrons

# set ResolutionFormula {resolution formula as a function of eta and energy}

# resolution formula for electrons
set ResolutionFormula { (abs(eta) <= 0.5) * (pt > 0.1) * sqrt(0.03^{2 + pt}2*1.3e-3^{2) +}

(abs(eta) > 0.5 && abs(eta) <= 1.5) * (pt > 0.1) * sqrt(0.05^{2 + pt}2*1.7e-3^{2) +
(abs(eta) > 1.5 && abs(eta) <= 2.5) * (pt > 0.1) * sqrt(0.15}2 + pt^2*3.1e-32)}

}

I understand the binary conditions (0 or 1 depending on the PT values), but what exactly does a higher resolution mean in this case? At higher Eta, is the accuracy of the PT measurement better or worse in this case? I see that the "resolution" is higher, but I don't know if that means poorer accuracy or better accuracy in measuring the "true" PT.

Thanks very much!

[Michele Selvaggi]

Bigger number in absolute terms means worse resolution. The numbers you see in the formula are used as the width of a gaussian smearing.