[Rivet] OPAL_2004_S6132243

[Peter Skands]

Hi Andy,

I was just wondering. ML is normally a 4-jet quantity, i.e., it is undefined 
(zero) for 3 particles or less. It may even be undefined for 4 partons, since it 
needs at least 2 of the partons to be on the "light" hemisphere which is not 
always the case. I don't know exactly how you compute the moments, but is it 
possible that something bad happens if there is an event with too few particles 
in the light hemisphere? That could conceivably happen only very rarely.

Peter

On 11/10/11 11:22 PM, Anton Karneyeu wrote:
> Hi Andy,
> I made a recheck with 1.7.0beta0 and still can see the problem - see attached
> pdf. Did you tried on lxplus?
>
> The full output which I see and script is here:
>
> /afs/cern.ch/user/a/akorneev/public/rivet
>
> Maybe something is wrong with my environment but I see the same issue in
> histograms coming from our BOINC cluster which are SLC5 i686 machines with
> minimal environment. Also, problem do not appear running small number of events,
> at least 100k events are necessary (probably it depends on random seed).
>
> Cheers,
> Anton
>
>
> On 10.11.2011 16:53, Andy Buckley wrote:
>> Hi Anton,
>>
>> Sorry about the delay, but with the trunk version of Rivet I don't see
>> any issue with these plots. I ran the PYTHIA default tune at 91 GeV and
>> your z2.params which specifies 133 GeV, and both worked fine. No NaNs in
>> any of the output files, and the plots look very reasonable (see attached).
>>
>> Do you still see this issue with the 1.7.0beta0 version? We do now also
>> have a beta1 tarball available, but unless you found any problems in the
>> beta0 testing I think we are ready to make our proper 1.7.0 release
>> tomorrow.
>>
>> Cheers,
>> Andy
>>
>>
>> On 06/10/11 21:19, Anton Karneyeu wrote:
>>> Hi guys,
>>>
>>> could you have a look on OPAL_2004_S6132243 analysis there is a problem
>>> with HemiMassLMom (d25-x01-yYY) histogram. In some cases histogram bins
>>> contents NaNs.
>>>
>>> Please, find in attachment the script which reproduce the problem on
>>> lxplus:
>>>
>>> $ ssh lxplus
>>> $ ./bug.sh
>>>
>>> Problematic histogram is
>>>
>>> S6132243/OPAL_2004_S6132243/d25-x01-y02.{dat,pdf,png}
>>>
>>>
>>> Cheers,
>>> Anton
>>>
>>>
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>>
>>