[Olympus] PRC report

[Douglas Kenneth Hasell]

Hi,

	I agree with Jan.  We must not produce anything yet showing data/MC.  Showing plots of data and MC in a log scale with arbitrary normalizations are okay but even this is dangerous if the normalizations are the same for electron and positrons.

	In the future I propose we avoid this problem by actually blinding the data we release to the collaboration.

                                                    Cheers,
                                                            Douglas

26-415 M.I.T.                                 Tel: +1 (617) 258-7199
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On Feb 5, 2014, at 12:26 PM, Jan C. Bernauer <bernauer at MIT.EDU> wrote:

> Dear all,
> 
> please do NOT do that. We are already dangerously close to produce and
> release a "result". To be honest, even the comparison like it is now is
> too close for comfort for me. The non-MC corrected yield in a log plot
> was the furthest I'm willing to go.
> 
> Dividing the measurement by MC gives almost directly the ratio we are
> after - you only have to divide the two numbers in the plot. This most
> certainly can not go in the PRC report. And quite frankly, I'm not sure
> why we even entertained the thought of blinding the data when we go and
> produce results, which will without doubt bias us, the first chance we get?
> 
> So I'm opposed to producing this plot even for internal use.
> 
> 
> With best regards,
> Jan
> 
> 
> On 2/5/14, 9:03 AM, Michael Kohl wrote:
>> Dear Stan, Yury,
>> 
>> the logarithmic scale is hiding certain features.
>> Can you produce a plot of the ratios (data/MC) for e+ and e- ? This should 
>> take out the leading Q2 dependence and help identify the problem zones.
>> 
>> The enhanced e- yield at backward angle was already present in Jan's plot 
>> from October.
>> 
>> Best regards
>>   Michael
>> 
>> 
>> On Wed, 5 Feb 2014, Belostotski, Stanislav wrote:
>> 
>>> Dear Douglas and Jan,
>>> Find please attached two plots (eps and pdf each)
>>> showing comparison experimental yields with MC. The normalization is
>>> done as follows:
>>> Experimental distributions are normalized one to another under condition
>>> that at Q2 around 1 GeV2 the ratio e+/e- must be equal to 1 ( as I
>>> understand we used the same philosophy as  Jan did) ;
>>> The e- MC points are normalized to experiment at Q2=0.65.
>>> I avoid to combine both plots in one (too messy). To be honest, they are
>>> anyway independent as we have not used normalization to luminosity.
>>> To me the results look good enough. The enhancement around Q2=4 for
>>> positrons has already been well explained by Jan. I am puzzled by excess
>>> of experiment over MC at Q2 larger 1.5 for electrons (somewhat similar
>>> but much less pronounced for positrons). Is that bgr contamination?
>>> Might be, but it looks rather as a shift by whatever reason.
>>> kind regards Stan,Yuri
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>> 
>> +---------------------------------------------------------------------
>> | Dr. Michael Kohl, Associate Professor and Staff Research Scientist
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> 
> 
> -- 
> Dr. Jan C. Bernauer
> Massachusetts Institute of Technology
> 77 Massachusetts Ave, Room 26-441
> Cambridge, MA, 02139, USA
> Phone:  (617) 253-6580
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