[Rivet] pT cut on B hadrons

[Kevin Finelli]

Hi Andy,
Thanks, this is perfect.  I think just having this option will also help
analysis writers to see that this cut doesn't come in by default, which
many of us thought was the case!
Regards,
Kevin

On Thu, Jul 30, 2015 at 9:40 PM, Andy Buckley <andy.buckley at cern.ch> wrote:

> Good! I've done it on the Rivet trunk: you can now say things like
>
> myjet.bTags(Cuts::pT > 5*GeV && Cuts::etaIn(2.5));
>
> and
>
> myjet.bTagged(Cuts::pT > 5*GeV);
>
> Hope this helps... when we get a new major version out. We're trying to
> speed up the release procedure so it might not be too long. Let's see ;-)
>
> Andy
>
>
>
> On 29/07/15 12:07, Christian Gutschow wrote:
>
>> Hi Andy, all,
>>
>> yes, please!
>> +1 for being able to use Cuts as an argument to bTags().
>> That's a much neater way of doing it..
>>
>> Cheers,
>> Chris
>>
>> On 29 July 2015 at 12:54, Andy Buckley <andy.buckley at cern.ch
>> <mailto:andy.buckley at cern.ch>> wrote:
>>
>>     Hi Kevin,
>>
>>     Thanks for the ping -- this had gone off my radar / I thought I had
>>     answered. I've copied this to the Rivet developer list, which is a
>>     more reliable place to ask questions due to more people & more
>>     expertise on the receiving end.
>>
>>     I'm not quite sure why you are asking: have you noticed a change in
>>     behaviour without the cut across Rivet versions? In general I think
>>     making cuts explicit is the right thing to do.
>>
>>     But I guess when you say that you are doing it manually that you
>>     really mean you are explicitly making a list of "b" particles with
>>     some kinematic cuts, then deltaR-matching those to the jets? We
>>     could/should allow the user to specify tag-particle cuts when
>>     configuring the FastJets projection, but right now you can do
>>     something like:
>>
>>     const Jets& myjets = applyProjection<FastJets>(evt, "Jets").jets();
>>     foreach (const Jet& j, jets) {
>>          foreach (const Particle& t, j.bTags()) {
>>              if (t.pT() > 5*GeV) // accept this jet
>>          }
>>     }
>>
>>     We can make this nicer to use, e.g. I imagine something like this
>>     would be helpful:
>>
>>     foreach (const Jet& j, jets) {
>>          if (j.bTags(Cuts::pT > 5*GeV).size() > 0) // accept this jet
>>     }
>>
>>     What do you think? It's an easy feature to add.
>>
>>     Andy
>>
>>
>>     On 29/07/15 02:20, Kevin Finelli wrote:
>>
>>         Hi Andy,
>>
>>         Just pinging again to see if you have had the chance to read this.
>>
>>         Thanks,
>>         Kevin
>>
>>         On Fri, Jul 24, 2015 at 5:06 PM, Alexander Grohsjean
>>         <Alexander.Grohsjean at desy.de
>>         <mailto:Alexander.Grohsjean at desy.de>
>>         <mailto:Alexander.Grohsjean at desy.de
>>
>>         <mailto:Alexander.Grohsjean at desy.de>>> wrote:
>>
>>              Hi Andy,
>>
>>              maybe to clarify. In the original code I provided, there
>>         was a cut
>>              of 5 GeV.
>>              When testing my implementation against the Rivet one using
>>         50 k events,
>>              as Kevin wrote, we got exactly the same yoda files out.
>>              That's why it is not clear if this cut was dropped between
>>         versions
>>              or if the 50k was not enough statistics to see any
>> difference.
>>
>>              Cheers, Alexander.
>>
>>
>>
>>
>>              Am 24.07.2015 um 04:31 schrieb Kevin Finelli:
>>
>>                  Hi Andy,
>>
>>                  We were hoping you could clarify the situation with pT
>>         cuts on B
>>                  hadrons used in truth jet b-tagging within Rivet.  In
>>         my own
>>                  tests, using 2.2, I have been "manually" applying the
>>         standard 5
>>                  GeV pT requirement on B hadrons needed for a jet to be
>>                  considered b-tagged.  This is now in the 7 TeV pseudotop
>>                  analysis (ATLAS_2015_I1345452), Chris G. submitted a
>>         patch about
>>                  a week ago.
>>
>>                  Looking back, I noticed the tt+jets analysis
>>                  (ATLAS_2014_I1304688) doesn't make this cut explicitly.
>>                  Alexander mentioned that this cut was not needed when the
>>                  analysis was tested, as two implementations of the ghost
>>                  association gave identical results in 50k events.
>>
>>                  Is it possible there was a cut in FastJets that changed
>>         in Rivet
>>                  2.2?  In any case it seems that we might want to go
>>         back now and
>>                  make this cut explicit in the tt+jets routine.
>>
>>                  Regards,
>>                  Kevin
>>
>>
>>
>>
>>
>>     --
>>     Dr Andy Buckley, Lecturer / Royal Society University Research Fellow
>>     Particle Physics Expt Group, University of Glasgow
>>     _______________________________________________
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>>
>>
>>
>
> --
> Dr Andy Buckley, Lecturer / Royal Society University Research Fellow
> Particle Physics Expt Group, University of Glasgow
>
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