[Frost] Question

[Steffen Strauch]

Dear Michael,

Yes, this is what I originally suggested for the experimentally determined sums over all events.

In the meantime, I think I need to revise the expressions and the numerator sum should read: cos(\alpha) and the denominator sum should read Q cos^2(\alpha).  This and the earlier expressions give the same results for constant background or if the observable does not change over the kinematic bin; like in our simplified examples.  Practically, the differences will be small.  However, when there are variations of the observable or of the background over a large bin (like in the double-pion case), the latter expressions give in my opinion results for the observable which are more meaningful.

I will update my slides and we can discuss this more during tomorrow’s meeting.

Steffen


> On Aug 17, 2016, at 1:21 PM, Michael Dugger <dugger at jlab.org> wrote:
> 
> 
> Steffen,
> 
> I just want to make sure I understand.
> 
> You weight each numerator event by
> 
> Q cos(\alpha)
> 
> and each denominator event by
> 
> [Q cos(\alpha)]^2 .
> 
> Is this correct?
> 
> Take care,
> Michael
> 
> On Wed, 17 Aug 2016, Steffen Strauch wrote:
> 
>> Dear Michael,
>> 
>> It is important that the weights in the moments in the denominator contain an additional factor of Q compared to the numerator.
>> 
>> I don’t think there is a typo here. If you compare on page 4 the two sets of moment ratios, you see that the first set already contains Q in the integral.  Weighing the cos(alpha) moment with an additional factor of Q, gives you the Q^2 in the integral of the numerator in the second set.  The denominator of the first set does not contain any Q in the integral.  So, an additional factor of Q^2 in the weight of the moment gives you the Q^2 in the integral of the denominator of the second set.
>> 
>> For the correct expression that the extracted value is the weighted average of P and not Q*P.
>> 
>> Thanks,
>> Steffen
>> 
>> 
>> 
>>> On Aug 17, 2016, at 12:06 PM, Michael Dugger <dugger at jlab.org> wrote:
>>> 
>>> 
>>> Steffen,
>>> 
>>> On last line of slide 4 and slide 5 of your pdf:
>>> 
>>> https://www.jlab.org/Hall-B/secure/g9/g9_strauch/mtg/FROST_meeting_2016_08_18.pdf
>>> 
>>> you show on the left hand side
>>> 
>>> Y_{Q cos\alpha}/Y_{Q^2 cos^2 \alpha},
>>> 
>>> where there is a factor of Q in the numerator and a factor of Q^2 in the denominator.
>>> 
>>> However, in the middle of the line you have Q^2 in both the numerator and denominator. Is there a typo?
>>> 
>>> If you have Q^2 in both the numerator and denominator, the expression will not work.
>>> 
>>> Take care,
>>> Michael
>>> _______________________________________________
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>>> Frost at jlab.org
>>> https://mailman.jlab.org/mailman/listinfo/frost
>> 
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