[Rivet] ALICE input to Rivet - MC points (Xi and Omega pp 7TeV, ALICE_2012_I1097057)

[Antonin Maire (IPHC)]

Hello again,

   David was the main actor for the Pythia simulation at the time of the 
paper.
We exchanged a few mails over the last days, to check we understand 
similarly again our own developments.

Among other things, Pythia 6 tunes Z1, Z2, Perugia 2011 simulations were 
carried out.
Pythia 8 was not tried at that time.
Perugia 2011 was the one of best performance so became the one we 
focused on.


_About the Pythia generation and analysis :_

- there is no special thing with the .cmnd config file.
The central tune Perugia 2011 (350) was used as it is.
The simlulated events are only "inelastic"  ones (i.e. allow for 
single+double diffraction on top of the non-diffractive processes).

- The MC analysis was performed via ROOT+TPythia6, so that TH1 can be used.


_MC points_


I enclose the table of values, taken from our macro to produce Fig.2 in 
http://arxiv.org/pdf/1204.0282v2.pdf.
- David is certainly ashamed that I show the underwear of his old code ( 
:-) ) but ok, let me give you some clarification in the naming of things.

1. You will see Z2 in every array name but has no meaning (except for Z2 
tune values...)

2. The pt binning of ALICE data was used.
     There are MC points simulated with the Xi binning (= 18 pT bins) 
and this also for the Omega spectra, and conversely, MC points with 
Omega binning (= 8 pT bins) also for the Xi spectra.
     Which binning is used where is indicated by the first particle name 
next to Z2, e.g. Z2XiSimulatedXiMinus

3. the Pythia values corresponds here to the integral of counts over 
each pT bin width = a bin content in the ROOT sense.
      Note these values ARE already further divided :
     - by Delta(pT), the pT bin width, i.e. normalised by unit of pT.
     - by the number of PYTHIA INEL events analysed

4. As a consequence of these normalised integral of counts,
     4.1 - the division of MC/data is kept straightforward
     4.2 - No need to worry about the right pT place to display the 
ratio MC/data (cf. Lafferty-Wyatt NIM paper) : the points are displayed 
at the centre of the pt bins.



_Comparison CMS/ALICE_

About the comparison of Xi+-(CMS) and Xi+-(ALICE), I enclose an exchange 
I had recently with Andreas on the topic.
The main point is NSD/INEL and the fact that CMS is not only Xi- but the 
sum of Xi- and anti-Xi+
http://mcplots.cern.ch/?query=plots,ppppbar,uemb-soft,Xim_pt
That CMS plot should maybe be moved next the ALICE 900 GeV (Xi-+Xi+) results
http://mcplots.cern.ch/?query=plots,ppppbar,uemb-soft,Xi_pt


We stay at disposal.


Cheers,
     David & Antonin


Le 04/06/2015 16:39, Jesper Roy Christiansen a écrit :
> Dear Boris and ALICE collaborators
>
> First of all thank you for providing the Rivet analysis, I have 
> already tried to run it to test how the new model compares (but I need 
> a bit more time before I am going to discuss that in details :)).
>
> I have also tried to compare this analysis with the Xi production 
> measured by CMS (CMS_2011_S8978280), and the models/data seems to be 
> quite different (the two analysis differs in that one is NSD, where as 
> yours is fully inelastic). But before drawing any conclusions, I would 
> first like to test whether I use the analysis correctly. I was 
> therefore wondering if you have the MC data that is shown in the 
> article available in a table format? That way I would be able to run 
> Pythia with the same tune and verify that I can get the same result as 
> is in your article (if you already did this, it is of course not 
> needed for me to do it). Otherwise if you for some reason still happen 
> to have the Pythia .cmnd file you used to generate the events used in 
> the article laying around, I would be very happy if you could send me 
> that (I know this is probably a bit too much to ask).
>
> Best regards
> Jesper
>
>
> On 06/03/2015 09:06 PM, Boris Hippolyte wrote:
>> Dear Andy,
>>
>> 1) we believe the relevant plots are already included in the targz
>> archive you received (in fact, these are very simple pT spectra
>> plus a mT-m0 ratio as contained in our 2012 publication).
>>
>> 2) we checked this rivet analysis of our data against PYTHIA 8
>> (not much statistics, admittedly) but we knew already that event
>> generators have significant difficulties with baryons, and even
>> more with multi-strange ones.
>> -> the hope is that Peter and Jesper (also in cc) will manage to
>> include these “rivetised" data for their next publication(s).
>>
>> 3) you can expect two other ALICE rivet contributions (related
>> to identified pT spectra) in the coming days.
>>
>> Best regards,
>> —B.
>> -----------------------------------------------------------------------------------
>> HIPPOLYTE Boris       B214 hippolyt at in2p3.fr <mailto:hippolyt at in2p3.fr>
>> Département de Recherches Subatomiques
>> Institut Pluridisciplinaire Hubert Curien
>> 23, rue du Loess Bat20 BP28           phone: +33(0)388106646
>> F-67037 Strasbourg cedex2             fax: +33(0)388106614
>> -----------------------------------------------------------------------------------
>>
>>> On Jun 3, 2015, at 15:40, Andy Buckley <andy.buckley at cern.ch 
>>> <mailto:andy.buckley at cern.ch>> wrote:
>>>
>>> Thanks Antonin,
>>>
>>> The analysis tarball is in the Rivet contrib downloads area now, and
>>> we'll integrate it into the next release. Great to have another ALICE
>>> analysis!
>>>
>>> Do you have any plots available from the analysis validation that we can
>>> put in the archive for future reference?
>>>
>>> Best wishes,
>>> Andy
>>>
>>>
>>> On 03/06/15 00:15, Antonin Maire (IPHC) wrote:
>>>> Good evening everybody,
>>>>
>>>>      I allow myself to contact you to provide an archive of a Rivet
>>>> analysis related to ( Xi-, anti-Xi+, Omega-, anti-Omega+) pT spectra
>>>> measured by ALICE.
>>>>
>>>> Multi-strange baryon production in pp collisions at (s)^1/2 = 7 TeV 
>>>> with
>>>> ALICE,
>>>> http://inspirehep.net/record/1097057
>>>> http://arxiv.org/abs/1204.0282
>>>>
>>>> The "rivetisation" of the analysis was done by Boris Hippolyte 
>>>> (thanks !).
>>>> David Chinellato and myself were "primary" analysers and authors of the
>>>> above paper.
>>>>
>>>> We propose this Rivet analysis to be integrated into the official
>>>> Rivet/src/Analyses
>>>> (first, I guess, via 
>>>> https://www.hepforge.org/archive/rivet/contrib/, up
>>>> to the next release).
>>>>
>>>> I stay at disposal.
>>>>
>>>> Antonin Maire, ALICE member
>>>>
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> Rivet mailing list
>>>> Rivet at projects.hepforge.org <mailto:Rivet at projects.hepforge.org>
>>>> https://www.hepforge.org/lists/listinfo/rivet
>>>>
>>>
>>>
>>> --
>>> Dr Andy Buckley, Lecturer / Royal Society University Research Fellow
>>> Particle Physics Expt Group, University of Glasgow
>>
>

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Salut Andreas,

I see 3 effects to keep in mind.

1. the dN/dy = f(y) is almost flat over +-2 units of rapidity.
It should be a minor effect.


2. The difference NSD (CMS)  and INEl (ALICE) is part of the solution :
1/Nnsd dN/dpt[Xi-(NSD)]   / 1/ Ninel dN/dpt[Xi-(INEL)]  ~ 1.26
(The effect comes essentially from the event normalisation not from the signal itself : Xi are ~all produced into NSD events)
See ALICE paper, http://arxiv.org/pdf/1204.0282v2.pdf, p.6


3. I have in mind, unlike the label may suggests, that CMS is the sum of particles and anti-particles
http://arxiv.org/abs/1102.4282
Tab.4, p.17 : dN( "Xi-" )/dy(CMS in |y|<0.2) = 0.021

While in ALICE we have :
http://arxiv.org/abs/1204.0282
Tab.2, p.6, dN(Xi-)/dy(ALICE in |y|<0.5) = 0.008

The corresponding Rivet Code seems to further confirm that.
https://rivet.hepforge.org/trac/browser/src/Analyses/CMS_2011_S8978280.cc
See :
- "p.abspid()"
- the fact that the code check for positive and negative ancestor PID...


I guess the combination of the last 2 effects will give sthg consistent at the end of the day.
(0.008 * 1.26 *2 ~ 0.020)

Cheers,
   Antonin
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