[b1_ana] (no subject)

[Elena Long]

Excellent! That's what I was hoping to hear.

Take care,
Ellie

Elena Long, Ph.D.
Post Doctoral Research Associate
University of New Hampshire
elena.long at unh.edu
ellie at jlab.org
http://nuclear.unh.edu/~elong
(603) 862-1962

On Thu 23 May 2013 10:30:42 AM EDT, Dustin Keller wrote:
> Truth be told the effects will probably be negligible for all points
> because of the size of our errors, mostly just want us to be aware of
> the issue in case a PAC member brings it up.
>
> dustin
>
> On Thu, 23 May 2013, Elena Long wrote:
>
>> So for our measurement of x<~0.6, we might have to worry about these
>> effects starting to come into play at the highest point but they
>> should have a negligible impact in the three lower points?
>>
>> Take care,
>> Ellie
>>
>> Elena Long, Ph.D.
>> Post Doctoral Research Associate
>> University of New Hampshire
>> elena.long at unh.edu
>> ellie at jlab.org
>> http://nuclear.unh.edu/~elong
>> (603) 862-1962
>>
>> On Thu 23 May 2013 09:58:58 AM EDT, Dustin Keller wrote:
>>> This is a very good and important question that remains
>>> unanswered.  Historically I think we have assumed that
>>> Azz~b1/F1 is good for x<1 but we also know the cut off
>>> is not sharp.  I think it is not yet understood theoretically
>>> how far in x b1 can be associated with Azz.  If b1 were to
>>> putter-out it would not be so much an issue.
>>>
>>> dustin
>>>
>>> On Thu, 23 May 2013, Elena Long wrote:
>>>
>>>> Good morning,
>>>>
>>>> Just for clarification, what are we considering low x and high x? I'm
>>>> assuming 0.5 falls in high x, but I was wondering approximately where
>>>> the cut off is for these effects to start becoming important.
>>>>
>>>> Thank you,
>>>> Ellie
>>>>
>>>> Elena Long, Ph.D.
>>>> Post Doctoral Research Associate
>>>> University of New Hampshire
>>>> elena.long at unh.edu
>>>> ellie at jlab.org
>>>> http://nuclear.unh.edu/~elong
>>>> (603) 862-1962
>>>>
>>>> On Wed 22 May 2013 07:03:12 PM EDT, Dustin Keller wrote:
>>>>> The Hoodbhoy, Jaffe and Manohar paper does express the final
>>>>> relationship
>>>>> to observables using the beam orientation, and there are several
>>>>> proceeding steps that get us to that point that are not covered.
>>>>> Its important to be critical of what we are actually measuring in
>>>>> terms of
>>>>> asymmetry and its definition.
>>>>>
>>>>> What we will be measuring is Azz or in Jaffes script ~b1/F1.  As an
>>>>> observable Azz seems to have a very generalized definition that
>>>>> does no
>>>>> change at various x regions but of course does have orientation
>>>>> dependence.  Assuming this is true allows us to bridge to the
>>>>> Arenhovel
>>>>> formalism.  Naturally for low x Jaffes relation is valid for a target
>>>>> helicity pointing along the electron beam.  In the Arenhovel
>>>>> formalism
>>>>> this is only an approximation, but a good one.  This approximation
>>>>> likely
>>>>> lives in the ratio b1/F1.  Because our last kinematic points may
>>>>> not be
>>>>> strictly thought of as low x its probably a little more accurate
>>>>> to use
>>>>> the corrections afforded to us by the Arenhovel formalism.  This
>>>>> would
>>>>> include a small correction to Azz from the Wigner rotation and
>>>>> possible a
>>>>> small correction from the vector target-only asymmetry.  By making
>>>>> these
>>>>> corrections for the higher x points the accuracy to Azz and b1/F1 is
>>>>> slightly increased.  This line of thinking would not be valid for the
>>>>> sigma_para - sigma_perp case in which you are acquiring b1
>>>>> directly.  But
>>>>> being we are measuring Azz we are not strictly using Jaffe for
>>>>> anything.
>>>>> To clarify, I can't think of any reason that for low x that one
>>>>> could not
>>>>> use the language Jaffe uses to describe the cross section in
>>>>> relationship
>>>>> to b1 and F1.
>>>>>
>>>>> The corrections to Azz come into play for higher x where
>>>>> pointing along the q-vector can lead to a measurable difference.
>>>>> So it
>>>>> maybe best to consider a response to any inquires from the PAC about
>>>>> this
>>>>> with some flexibility around q-vector orientation.  As it is the
>>>>> correction
>>>>> to Azz is a multiplicative factor of ~0.9 and the target-only vector
>>>>> asymmetry is near negligible.
>>>>>
>>>>> dustin
>>>>>
>>>>> _______________________________________________
>>>>> b1_ana mailing list
>>>>> b1_ana at jlab.org
>>>>> https://mailman.jlab.org/mailman/listinfo/b1_ana
>>>>
>>