Monday, July 28, 2008
Some plots
What I've been doing is ID-ing the electrons and then forcing everything else to 2 jets. This means I'd have to do my own jet finding and flavour tagging if using mass reconstruction files in the future.
Variables used in the likelihood cut
The thrust variables don't seem to do much, and the jet energy difference doesn't offer great discrimination. We still need to add the di-jet mass after the 5 constraint fit to this.
Flavour tag likeness for the Higgs sample (using the c-tag)
These plots look fairly good; there is a definite difference between each different plot that should be extractable from the branching ration fit.
Flavour tag likeness for the ZZ sample (both c-tag and bc-tag)
Same here for the ZZ. I've also added the same plot but using the c-with-only-b-background tag, although this doesn't show much (see the next set of plots). There also doesn't seem to be much tagged as c in the c-tag version. I'll have to look into that.
Flavour tag likeness for the Higgs sample (using the bc-tag)
The bc-tag just seems to tag anything that's not a b as a c (not really very surprising since that's what it's trained to do). All the templates (except the b) look pretty much the same, so not very good for fitting to.
Electron ID comparison
The next four plots compare the different electron identification methods. Everything is using a Z Higgs sample with the Z going to two electrons and the Higgs doing whatever it fancies, so there is some neutrino stuff in there as well from e.g. Higgs->WW. There's a total of 43888 events split according to standard model 120GeV Higgs branching ratios.
Note that anything labelled as "Pandora" is using a head version of PandoraPFA from a couple of weeks ago. A new tag has recently been released which claims to have improved electron ID, I'll try and redo the plots with the new version soon.
Di-jet mass of everything not identified as an electron forced to 2 jets
There are no cuts on any of these plots, so some of the high tails should be reduced if I cut out anything where less than 2 electrons are found (see below).
Di-electron mass of everything identified as an electron
I've called this "di-electron" mass but quite often there are more than 2 electrons involved, see the next plot for the numbers. Note that I forgot to put a cut on the number found, so the spikes at zero are when 1 or no electrons are identified.
Numbers of electrons found
The cheated electron code takes the Monte Carlo Z daughters and uses the LCRelation collection to match them to reconstructed particles. If more than one reconstructed particle is related to a particular electron then they are all lumped into one "jet" and the combined four momentum used for the cheated electron. As such I have no idea how it can find more than 2 (let alone 6?). I'll have to look into it when I get time. Addendum 06/Aug/08 - The Higgs sample has Higgs to ZZ, hence the possibility of 4 or 6 electrons from Zs. Doh!
Recoil mass using the electrons found
For this the initial four momentum was assumed to be a consistent (250,0,0,0); so you can clearly see the beam effects screwing up the plot. Have a look at one of my earlier posts to see how I simulated beamstrahlung; basically it's just a rough (over)estimate using 500GeV beam parameters.
Variables used in the likelihood cut
The thrust variables don't seem to do much, and the jet energy difference doesn't offer great discrimination. We still need to add the di-jet mass after the 5 constraint fit to this.
Flavour tag likeness for the Higgs sample (using the c-tag)
These plots look fairly good; there is a definite difference between each different plot that should be extractable from the branching ration fit.
Flavour tag likeness for the ZZ sample (both c-tag and bc-tag)
Same here for the ZZ. I've also added the same plot but using the c-with-only-b-background tag, although this doesn't show much (see the next set of plots). There also doesn't seem to be much tagged as c in the c-tag version. I'll have to look into that.
Flavour tag likeness for the Higgs sample (using the bc-tag)
The bc-tag just seems to tag anything that's not a b as a c (not really very surprising since that's what it's trained to do). All the templates (except the b) look pretty much the same, so not very good for fitting to.
Electron ID comparison
The next four plots compare the different electron identification methods. Everything is using a Z Higgs sample with the Z going to two electrons and the Higgs doing whatever it fancies, so there is some neutrino stuff in there as well from e.g. Higgs->WW. There's a total of 43888 events split according to standard model 120GeV Higgs branching ratios.
Note that anything labelled as "Pandora" is using a head version of PandoraPFA from a couple of weeks ago. A new tag has recently been released which claims to have improved electron ID, I'll try and redo the plots with the new version soon.
Di-jet mass of everything not identified as an electron forced to 2 jets
There are no cuts on any of these plots, so some of the high tails should be reduced if I cut out anything where less than 2 electrons are found (see below).
Di-electron mass of everything identified as an electron
I've called this "di-electron" mass but quite often there are more than 2 electrons involved, see the next plot for the numbers. Note that I forgot to put a cut on the number found, so the spikes at zero are when 1 or no electrons are identified.
Numbers of electrons found
The cheated electron code takes the Monte Carlo Z daughters and uses the LCRelation collection to match them to reconstructed particles. If more than one reconstructed particle is related to a particular electron then they are all lumped into one "jet" and the combined four momentum used for the cheated electron. As such I have no idea how it can find more than 2 (let alone 6?). I'll have to look into it when I get time. Addendum 06/Aug/08 - The Higgs sample has Higgs to ZZ, hence the possibility of 4 or 6 electrons from Zs. Doh!
Recoil mass using the electrons found
For this the initial four momentum was assumed to be a consistent (250,0,0,0); so you can clearly see the beam effects screwing up the plot. Have a look at one of my earlier posts to see how I simulated beamstrahlung; basically it's just a rough (over)estimate using 500GeV beam parameters.
Tagging plots for true C jets
Sorry about the sideways!
Questions: why is the C-tag bad? Do we use the BC tag for these events?
Tagging plots for the ZHiggs sample
These plots are found using the Durham_4Jets collection. So two of the jets represent the muons.
Electron cut efficiency
The change due to new detector model is seen in the ratio of Ecal energy and the total energy, due to which we have changed our electron cuts. Now it is
1) Ecal/ETot = 0.9
2) ETot/p = 0.7
So with the new detector model, above cuts and more statistics, the efficiency for momentum and cos theta is here
Monday, July 21, 2008
Useful LCIO commands
Some time ago, Mark had problems with a large lcio file. Now I have the same problem. I found on the web the command
lcio split -i file.slcio -n 1000
that splits the file in chunks of 1000 events.
For more LCIO comands, see here.
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