[Rivet] Rivet Jet Analysis

[ST Harnew]

Thanks for both of your input!

I will give the rivet-mergeruns script a try tomorrow and see how the plots 
turn out. From looking at all the pT cuts plotted on top of each other (see 
attached) I should end up with a fairly smooth distribution with the 
correct merge points.

Using weighted events definitely seems like the best option in the long 
run, especially when I start tuning to the UE data and processing time 
becomes more of an issue. I have gone through the Pythia 8 guide and can't 
see any clear way of doing this. Does anyone know a way to do it?

Many thanks,

Sam Harnew

--On 31 January 2011 15:42 +0000 Andy Buckley <andy.buckley at ed.ac.uk> wrote:

> On 31/01/11 15:26, Hendrik Hoeth wrote:
>> Hi Sam,
>>
>> Thus spake Andy Buckley (andy.buckley at ed.ac.uk):
>>
>>>> For the CDF_2008_LEADINGJETS  <Nch> against pT(leading jet) plots, the
>>>> runs from each pT cut are needed to fill a single histogram. Should I
>>>> deal with this by chopping each histogram down to its valid region (say
>>>> 0-20 pT for the minimum bias run, then 20-100pT for the pTmin=10GeV run
>>>> etc) then stick all these together to make a complete distribution? Or
>>>> is there a smarter way of doing this.
>>
>> Currently we do exactly that. There is a script that can do the
>> histogram slicing and merging for you: rivet-mergeruns. It's a bit
>> awkward to use, since it's not exactly aimed at end-users, but
>> nevertheless. Here is how I used it in a recent Pythia-8 production:
>>
>> rivet-mergeruns CDF_2008_LEADINGJETS_CKIN0/Rivet.aida:1960:0 \
>>                 CDF_2008_LEADINGJETS_CKIN10/Rivet.aida:1960:30 \
>>                 CDF_2008_LEADINGJETS_CKIN20/Rivet.aida:1960:50 \
>>                 CDF_2008_LEADINGJETS_CKIN50/Rivet.aida:1960:80 \
>>                 CDF_2008_LEADINGJETS_CKIN100/Rivet.aida:1960:130 \
>>                 CDF_2008_LEADINGJETS_CKIN150/Rivet.aida:1960:180 \
>>                 > foo.dat
>> flat2aida foo.dat
>>
>> You have to specify <aidafile>:<energy>:<mergingpT>. Note that you need
>> to set the histogram merging pT a fair bit higher than the generator
>> level cut!
>
> And also note that the analyses that it applies to and how it merges
> them is determined not by the command line (which just tells the script
> which .aida files should be considered as appropriate at which energy
> and above which pT cut) but by hard-coded declarations in the script
> itself! That's why Hendrik says that it's not really intended for
> end-user use... and why I didn't mention it ;) You can hack the script
> for your own purposes if it doesn't already handle all the analyses that
> you need... but from what you mentioned in your previous mail, I think
> it does.
>
> However, I still strongly think that pT-enhancement/weighting is a
> better way. PYTHIA 6 had a limited version of that so *surely* Pythia 8
> has something... and hopefully more configurable, too. With the approach
> above, you can only merge multiple runs together inside a single
> (profile) histogram if that histogram is binned in the pT of a leading
> jet -- because that is effectively the quantity that the generator-level
> cut is applied on. But the pT-enhancement method will work for general
> histograms, and will fill such pT_lead profiles with smooth statistics
> rather than the sort of sawtooth that comes from merging together
> different single-cut pT slices.
>
> Cheers,
> Andy
>
> --
> Dr Andy Buckley
> SUPA Advanced Research Fellow
> Particle Physics Experiment Group, University of Edinburgh
>
> The University of Edinburgh is a charitable body, registered in
> Scotland, with registration number SC005336.
>



----------------------
ST Harnew
sh7566 at bristol.ac.uk
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