Added a module to do eta filtering for Egamma HLT candidates

[arsahasransu]

PR description:

• Added a module to do eta filtering of HLT Egamma objects
• Necessary for an eta cut on objects in the trigger HLT_DiPhoton10Time1p2ns_v

PR validation:

• Checked the functionality of the filter module and verified that the eta cuts function as intended. A basic plot is shown below.
• The red histogram is after the eta cut while the blue histogram is before cut. An |eta|<2.15 has been applied as can be observed by comparing the plots.
• Code checks and code format performed

PR backport:

• PR needs to be backported to CMSSW_12_4_X and 12_5_X
• The current software at HLT is in the 12_4_X release. Hence the need for backport.

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-39764/32627

• This PR adds an extra 12KB to repository

[cmsbuild]

A new Pull Request was created by @arsahasransu (A.R.Sahasransu) for master.

It involves the following packages:

• HLTrigger/Egamma (hlt)

@cmsbuild, @missirol, @Martin-Grunewald can you please review it and eventually sign? Thanks.
@Martin-Grunewald, @missirol, @silviodonato this is something you requested to watch as well.
@perrotta, @dpiparo, @rappoccio you are the release manager for this.

cms-bot commands are listed here

[Martin-Grunewald]

Why is this needed? Did you check that the producer of the collection could (not) apply the eta cut? Have you checked that existing filters can not do the task? Eg, have a look at the several HLTGeneric filters within HLTrigger/Egamma.

[arsahasransu]

Why is this needed? Did you check that the producer of the collection could (not) apply the eta cut? Have you checked that existing filters can not do the task? Eg, have a look at the several HLT_Generic_ filters within HLTrigger/Egamma.

@Martin-Grunewald
The hltEgammaCandidates and hltEgammaCandidatesUnseeded are produced for multiple paths. I do not want to add another producer just for these triggers. Hence I couldn't filter for eta at the producer level. I also checked other filters but couldn't figure out a way to use them for cutting the eta of the HLT egamma candidate. Some of these are below:

HLTGenericFilter requires variable tags that it does the selection on. https://github.com/cms-sw/cmssw/blob/master/HLTrigger/Egamma/plugins/HLTGenericFilter.cc#L29 The same also applies for the HLTElectronGenericFilter.

I also looked in the general HLT filters hoping to find an eta filter. The HLTFiltCan at https://github.com/cms-sw/cmssw/blob/master/HLTrigger/HLTfilters/plugins/HLTFiltCand.cc only provides options for pT.

If there is a way to implement the eta cut without adding this class, it is the most optimal, and please help me find this.

[Martin-Grunewald]

You could see whether to add an eta cut to an existing filter, with default eta cut values such that the eta cut is not rejecting anything (though HLTFiltCand is not a good example). Otherwise, ok, add this new class.

[arsahasransu]

You could see whether to add an eta cut to an existing filter, with default eta cut values such that the eta cut is not rejecting anything (though HLTFiltCand is not a good example). Otherwise, ok, add this new class.

Yes, I was thinking the same. Do you recommend adding the eta cut to, let's say, the Et Filter class?

[Martin-Grunewald]

Yes, for example there. Also, consider whether to just have an upper cut on abs(eta) rather than a min and a max cut on the signed eta.

[arsahasransu]

Yes, for example there. Also, consider whether to just have an upper cut on abs(eta) rather than a min and a max cut on the signed eta.

I put a min and max Eta to allow for asymmetric cuts. At some point, these can be changed to vectors to allow for eta cut in multiple windows if someone gets interested in that. It is just allowing for flexibility without any particular trade-off.