[Rivet] Rivet for powheg-pythia8 studies

[Andy Buckley]

(CC'ing the Rivet list, since these are general Rivet questions: that is
the best contact place)

On 23/10/13 07:46, Liron Barak wrote:
> OK, thanks!
> The plan/request was that I'll compare my powheg-pythia8 trials
> (with/out main31/SpaceShower/TimeShower etc) with data, but the output
> of my powheg-pythia8 trials is evgen/truthD3PDs.... can that be used
> instead?

Not directly into Rivet, because those are ATLAS-format files. But you
can use Rivet through Athena:
https://twiki.cern.ch/twiki/bin/viewauth/AtlasProtected/RivetForAtlas

> Also, there are some things I do following the paper but i'm not sure about:
> 1. Should I do:
> source rivetenv.sh
> source agileenv.sh
> If I use z shell? It is written at the end of the installation that it
> is for bash....

No idea! I think the sh form should work, but I'm not familiar with zsh
(or ksh). What do you do with other setup.sh files, e.g. the ones to set
up LCG's GCC? Let me know!

> 2. When I do
> agile-runmc --beams=pp:14000 Pythia6:426 (I don't have pythia6.425 on my
> list when I do agile-runmc --list-gens)
> I don't get anything new.... I do get prints on the screen saying:
> Generating 10 events
> Generator is Pythia6:426
> Number of points... generated... trys etc
> But I don't get any new file with the events?! It doesn't stop me from
> continue of course....

You need to use a -o flag (as in the docs) to write out the events.

> 3. Do you have any Command completion for z shell? I just ignored it for
> now...

No... it was enough effort to write it for bash, and I think the zsh
mechanism is quite different. It also doesn't work for csh.

> 4. Doing 'mkfifo fifo.hepmc' just created 'fifo.hepmc' which is empty?

Erm, yes. It's a FIFO -- a special "file" for piping data between processes.

> 5. Doing 'agile-runmc Pythia6:426 -o fifo.hepmc &' just print out [1]
> 30886 and did nothing?

Did you read from the other end of the pipe?

> 6. Where exactly that FIFO part used? It is not so clear to me..... so
> I'm not sure if I should do it for each thing?

You need to attach rivet to the other end of the pipe for something to
happen. The manual covers this -- is there something we can do to
improve it?

> 7. I guess by doing 'agile-runmc Pythia6:426 --beams=LHC:14TeV -n 50 -o
> out.hepmc' I get the needed inputs, so, how can I use my
> evgen/truthD3PDs from powheg-pythia8 instead of that out.hepmc?

Use Rivet in Athena, or use Athena to dump a .hepmc file. I would do the
former.

> 8. Will using MC_TTBAR is the right thing? It sound like the same BUT
> with no mentioning of the comparison to data...... 

There is no comparison to data in the MC_ analyses: they are just for
MC-to-MC comparisons, or sanity checking. Unfortunately I don't think
there are any public differential top observables which have been
unfolded other than the ATLAS ttbar jet veto analysis... hence the
difficulty in optimising generator setups for ttbar. I think the Top
community are starting to realise this!

> 9. Which data files are used? 

What do you mean?

Andy




> On Tue, Oct 22, 2013 at 9:54 PM, Andy Buckley <andy.buckley at cern.ch
> <mailto:andy.buckley at cern.ch>> wrote:
> 
>     On 22/10/13 10:28, Liron Barak wrote:
>     > Dear Andy,
>     >
>     > I try to use that Rivet tool for the comparison of the various
>     > powheg-pythia8 options I made with data!
>     > I'm only at section 3.1 in your paper
>     > (http://arxiv.org/pdf/1003.0694v8.pdf) but already have a stupid
>     > question....
>     > What is the exactly the input of the MC? It says hepmc, but is
>     > it HepMC.root that I get when I run Generate_trf? The
>     evgen.pool.root I
>     > get when I run Generate_trf? Something else? Because for some sherpa
>     > trials I have *.hepmc file made by the theoreticians and I'm not sure
>     > what is what?!
> 
>     It's the "IO_GenEvent" ASCII file format that is being referred to in
>     the manual. That's probably what the .hepmc file is -- take a look
>     inside it. The ROOT files produced by Generate_trf are a histogram file
>     and an ATLAS-specific POOL mapping respectively.
> 
>     Andy
> 
>     --
>     Dr Andy Buckley, Royal Society University Research Fellow
>     Particle Physics Expt Group, University of Glasgow / PH Dept, CERN
> 
> 


-- 
Dr Andy Buckley, Royal Society University Research Fellow
Particle Physics Expt Group, University of Glasgow / PH Dept, CERN