[Rivet] pT cut on B hadrons

[Andy Buckley]

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