[Rivet] Jet constituents after smearing

[Andy Buckley]

Are you sure this is appropriate? Normally efficiency is not a significant
issue for (calo) jet constituents. I don't know of per-particle smearing
info for clusters, but would be interested to know... I think Delphes has
endured a shearing function like this, but no idea where their numbers came
from.

Re. the 10 GeV cut, this is again an efficiency, and it's appropriate for
identified prompt particles, not for calo jet constituents. You'll get
numbers out, but I'm sceptical about them bearing any similarity to
full-sim. It'd be interesting to try the comparison, though: let me know if
you'd like to follow that up in ATLAS.

Andy

On 4 Mar 2018 20:32, "Deepak Kar" <deepak.kar at cern.ch> wrote:

> Hi Andy,
>
> Thanks for the suggestions. I did manage to create a fatjet with smeared
> constituents now, with one caveat. I had to switch to using charged
> particles only to use track efficiency, in order not to have 10 GeV pT cut
> which other smeared objects have.
>
> Something we can follow up in the May meeting, if and when that happens.
>
> Cheers,
> Deepak
>
> On Fri, Mar 2, 2018 at 3:15 PM, Andy Buckley <andy.buckley at cern.ch> wrote:
>
>> The latter should be possible, but not currently via the normal
>> projection route: SmearedParticles inherits from ParticleFinder, while
>> FastJets accepts a more specific FinalState projection as its source of
>> particles. This is something to generalise, but last time I tried it turned
>> out to be more involved than you might expect.
>>
>> You should be able to use FastJets "interactively" via its calc()
>> mechanism, though, e.g. somefastjetsproj.calc(smearedparticlesproj.particles());
>> somefastjetsproj.jets(). We could/should also make that neater...
>>
>> In response to the earlier question (I'm just back online after holiday),
>> there's nothing specific to particle charge about the SmearedParticles
>> mechanism, but the generic built-in smearing functions are mostly for
>> well-isolated, fairly hard, identified particles. Constituent-level
>> smearing for jet (substructure) reco would require something more specific
>> than the built-ins -- that's part of why we *don't* currently smear the
>> constituents of smeared jets (although I forget, do we rescale their
>> momenta to be consistent with the jet momentum?) You can write your own
>> constituent-smearing function fairly easily, though, with as simple or
>> complex a smearing algorithm as you need.
>>
>> Andy
>>
>> *Dr Andy Buckley, Lecturer / Royal Society University Research Fellow*
>> Particle Physics Experiment Group, University of Glasgow
>> On Feb 28 2018, at 7:16 pm, Deepak Kar <deepak.kar at cern.ch> wrote:
>>
>>
>> Hi all,
>>
>> Following up on my previous email, is there a way I can use
>> SmearedParticles as inputs to jet forming?
>>
>> Thanks,
>> Deepak
>>
>> On Mon, Feb 26, 2018 at 8:05 PM, Deepak Kar <deepak.kar at cern.ch> wrote:
>>
>> Dear experts,
>>
>> I am trying to calculate some jet substructure variables (using fastjet
>> contrib) of a smeared jet. Now it looks like only the jet is smeared, and
>> the constituent information is lost. I guess the right way will be to smear
>> the constituents before making the jet, but I could not see a generic
>> smearing for charged and neutral particles. I can probably hack the
>> electron smearing to apply it on cnfs, but is there an elegant way?
>>
>> Thanks,
>> Deepak
>>
>> --
>> Deepak Kar
>> University of Witwatersrand
>> Room PM15, School of Physics
>> (0027) 011-7176958 <+27%2011%20717%206958> (office) (0027) 0736944181
>> <+27%2073%20694%204181> (mobile)
>>
>> While at CERN:
>> Building 1, R-016
>> (0041) 0767321349 <+41%2076%20732%2013%2049> (mobile)
>>
>> While at USA:
>> (001) 330-998-1500 <(330)%20998-1500> (mobile)
>>
>>
>>
>>
>> --
>> Deepak Kar
>> University of Witwatersrand
>> Room PM15, School of Physics
>> (0027) 011-7176958 <+27%2011%20717%206958> (office) (0027) 0736944181
>> <+27%2073%20694%204181> (mobile)
>>
>> While at CERN:
>> Building 1, R-016
>> (0041) 0767321349 <+41%2076%20732%2013%2049> (mobile)
>>
>> While at USA:
>> (001) 330-998-1500 <(330)%20998-1500> (mobile)
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>>
>
>
> --
> Deepak Kar
> University of Witwatersrand
> Room PM15, School of Physics
> (0027) 011-7176958 <+27%2011%20717%206958> (office) (0027) 0736944181
> <+27%2073%20694%204181> (mobile)
>
> While at CERN:
> Building 1, R-016
> (0041) 0767321349 <+41%2076%20732%2013%2049> (mobile)
>
> While at USA:
> (001) 330-998-1500 <+1%20330-998-1500> (mobile)
>
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