[Rivet] Validation & tuning phone meeting, Monday 29th Sept, 4pm (UK)

[Jonathan Butterworth]

Since Emily tuned without Jimmy, its probably worth trying with MSFLAG=0 
(i.e. no Jimmy). You also need PRSOF=0 (turn of the soft underlying event).

If you do turn on JIMMY, I recommend
JMUEO = 1
MSFLAG = 1
PTJIM = 2.8
PRRAD = 1.8

This is the current ATLAS tune.

Cheers,
Jon

Emily Nurse wrote:
> Hi Lars,
> 
> It doesn't look like the HERWIG plots are normalised to the data, is  
> this right?
> Could you do that? Otherwise its hard to see how well the shapes agree.
> 
> I'm surprised by how badly the MC is describing the low pT region.
> For the HERWIG parameters you could try:
> 
> PTRMS = 1.6
> VQCUT = 0.45
> QCDLAM = 0.14
> 
> but these were tuned without Jimmy so may not be the best fit when  
> you run with Jimmy.
> 
> I'm surprised that the ratio plot is still going in the opposite  
> direction to the data even after scaling the Z pT by Mw/Mz.
> The Z pT distribution peaks higher than the W pT because of the  
> higher Z mass (more phase space available for gluon radiation at that  
> energy). So without the scaling I would expect the W : Z ratio to  
> decrease with pT. With the scaling it should go slightly the other  
> way (I think because alpha_s is weaker at Q=Mz than at Q=Mw). This is  
> what I saw when I did this study with HERWIG and what the data sees.  
> So something funny is going on.
> 
> Could I take a quick look at your running parameters/switches and the  
> routine?
>> Concerning the overal normalisation there is an ambiguity:
>> boson->tau->electron.
>> I didn't switch this on, since the papers only talk about boson->e('s)
>> without intermediate tau. This would increase the xsec roughly by  
>> 1/3, but
>> the pT spectrum of the electrons from taus is also a little bit  
>> different.
>> So if I would switch boson->tau on, it depends on how the  
>> experiment has
>> corrected (to boson->e('s) or to boson->e('s) + boson->tau('s)->e 
>> ('s)).
>>
> 
> You should run only Z->ee and W->enu, no tau final states. The number  
> of Z->tautau and W->taunu events passing the cuts will be small (the  
> electron pT spectrum is much softer) and the experiments will have  
> (should have) included it as a background.
> 
> Cheers,
> Emily.
> 
>>
>> On Mon, 6 Oct 2008, Emily Nurse wrote:
>>
>>> Hi Lars,
>>>
>>> I think you will need to correct for the branching ratio  
>>> difference as this is
>>> a ratio of production cross sections , so your formula
>>>> R_th = dsigma/dpt(W) / dsigma/[d(pt(Z)*Mw/Mz)] *
>>>> B(Z->ee)/B(W->enu)
>>> looks correct - although its been a long time since I read the  
>>> paper. If the
>>> normalisation looks off lets re think it.
>>>
>>> Cheers,
>>> Emily.
>>>
>>> On 6 Oct 2008, at 09:48, Lars Sonnenschein wrote:
>>>
>>>> Hello Emily
>>>> thank you for your feedback.
>>>> Indeed the paper has two formulas for the ratio:
>>>> a theoretical one which corresponds to your formula below and an
>>>> experimental one which looks like:
>>>>
>>>> R_exp(pT) = [dsigma/dpt(W) / dsigma/dpt(Z)] * Mw/Mz * B(Z->ee)/B 
>>>> (W->enu)
>>>>
>>>> where Mw/Mz = 0.88 and B(Z->ee)/B(W->enu) = 0.3 roughly.
>>>> The later formula I use for the ratio, i.e. scale the diff. xsec.  
>>>> ratio
>>>> by the constant factors given above.
>>>>
>>>> Now I could scale the Z pT before filling the histo according to the
>>>> theoretical formula, but that would not alter the W pT spectrum.
>>>>
>>>> Though I will try to see the difference in the ratio.
>>>>
>>>> Now, since I select electrons (and  a neutrino in case of W)  
>>>> should the
>>>> formula look like R_th = dsigma/dpt(W) / dsigma/[d(pt(Z)*Mw/Mz)] *
>>>> B(Z->ee)/B(W->enu)
>>>> to take the branching ratio differences into account?
>>>>
>>>>      Lars
>>>>
>>>>
>>>> On Mon, 6 Oct 2008, Emily Nurse wrote:
>>>>
>>>>> Hi Lars,
>>>>>
>>>>> Its hard to see how off the W pT plot is, can you compare it to  
>>>>> the data
>>>>> so we
>>>>> can see?
>>>>> As for the ratio, its more obvious that its going the wrong way  
>>>>> compared
>>>>> to
>>>>> the data.
>>>>> In the paper they are measuring dsigma/dpt(W) / dsigma/[dpt(Z) 
>>>>> *Mw/Mz]
>>>>> ie/ they scale the Z pT by the ratio of the W and Z masses, see  
>>>>> page 20
>>>>> and 21
>>>>> of my 1st year PhD transfer report for more details, and  
>>>>> comparisons of
>>>>> the
>>>>> data with Herwig:
>>>>> http://www.hep.man.ac.uk/u/emily/1styear.ps
>>>>>
>>>>> It should also be explained in the paper. Are you doing this in the
>>>>> routine?
>>>>>
>>>>> Cheers,
>>>>> Emily.
>>>>>
>>>>>
>>>>> On 6 Oct 2008, at 08:19, Lars Sonnenschein wrote:
>>>>>
>>>>>> Hi
>>>>>> I have put some plots for the D0 2001 WpT <-> ZpT analysis at
>>>>>> http://www-d0.fnal.gov/~sonne/D0_2001_S4674421/
>>>>>>
>>>>>>      Lars
>>>>>>
>>>>>>
>>>>>> On Fri, 3 Oct 2008, Andy Buckley wrote:
>>>>>>
>>>>>>> Hi everyone,
>>>>>>>
>>>>>>> Our next Rivet etc. phone meeting will take place on Monday at  
>>>>>>> 2pm (UK
>>>>>>> time). Note that it's earlier than last week - this will be  
>>>>>>> the normal
>>>>>>> time from now on.
>>>>>>>
>>>>>>> Once again, we'll be using the DESY phone conference system:  
>>>>>>> phone
>>>>>>>
>>>>>>> +49 40 8998 1390
>>>>>>>
>>>>>>> then enter conference code 74838 ("rivet") followed by #.
>>>>>>>
>>>>>>> From the UK, Telediscount can be useful if your office restricts
>>>>>>> international dialling: 0844 861 3535.
>>>>>>>
>>>>>>> Have a good weekend!
>>>>>>> Andy
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> Rivet mailing list
>>>>>>> Rivet at projects.hepforge.org
>>>>>>> http://www.hepforge.org/lists/listinfo/rivet
>>>>>>>
>>>>>> -- 
>>>>>>
>>>>>>
>>>>>> ________________________________
>>>>>> Lars Sonnenschein
>>>>>> ________________________________
>>>>>> Home Institution:
>>>>>> PH/TH 53/1-052
>>>>>> CERN
>>>>>> CH-1211 Geneve 23
>>>>>> Switzerland
>>>>>> Tel.:+41(22)767-2801
>>>>>> --------------------------------
>>>>>> ________________________________
>>>>>> FNAL:
>>>>>> D0, PK151
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>>>>>> ________________________________
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>>>>>
>>>> -- 
>>>>
>>>>
>>>> ________________________________
>>>> Lars Sonnenschein
>>>> ________________________________
>>>> Home Institution:
>>>> PH/TH 53/1-052
>>>> CERN
>>>> CH-1211 Geneve 23
>>>> Switzerland
>>>> Tel.:+41(22)767-2801
>>>> --------------------------------
>>>> ________________________________
>>>> FNAL:
>>>> D0, PK151
>>>> Mailstop #352
>>>> Fermilab, P.O.Box 500
>>>> Batavia, IL 60510-500
>>>> USA
>>>> Tel.: +1(630)840-8740
>>>> ________________________________
>>>
>> -- 
>>
>>
>> ________________________________
>> Lars Sonnenschein
>> ________________________________
>> Home Institution:
>> PH/TH 53/1-052
>> CERN
>> CH-1211 Geneve 23
>> Switzerland
>> Tel.:+41(22)767-2801
>> --------------------------------
>> ________________________________
>> FNAL:
>> D0, PK151
>> Mailstop #352
>> Fermilab, P.O.Box 500
>> Batavia, IL 60510-500
>> USA
>> Tel.: +1(630)840-8740
>> ________________________________
> 
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-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Prof. Jonathan Butterworth,              http://www.hep.ucl.ac.uk/~jmb/
Physics and Astronomy Department                  Tel: +44 20 7679 3444
ATLAS, CERN                                       Tel: +41 22 76  72340
University College London                 Gower St, London WC1E 6BT, UK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~