[b1_ana] b1d

[Karl Slifer]

---------- Forwarded message ----------
From: "Simonetta Liuti" <sl4y at cms.mail.virginia.edu>
To: "O. A. Rondon" <or at virginia.edu>, "Simonetta Liuti" <sl4y at virginia.edu>,
<kk7t at virginia.edu>, <b1 at jlab.org>
Cc: "Karl Slifer" <karl.slifer at unh.edu>, "Donal Day" <
dbd at cms.mail.virginia.edu>, "Patricia Solvignon" <solvigno at jlab.org>,
"Narbe Kalantarians" <narbe at jlab.org>, "J.P. Chen" <jpchen at jlab.org>, <
ellie at jlab.org>, "Donald G. Crabb" <dgc3q at cms.mail.virginia.edu>, "Dustin
Keller" <dustin at jlab.org>
Date: Fri, 15 Mar 2013 09:54:25 -0400
Subject: Re: b1d

Dear All,
yes, we had a very productive meeting with Oscar, Dustin and Kunal! (I
should say that I am in fact also glad I learned about your b_1 proposal
from Patricia's talk at INT).

Thanks for the references. Will read.

To summarize, we have agreed  that in the next couple of weeks (before the
collaboration conference call two Mondays from now), we will perform a
study of the observables based on the helicity amplitudes. In a nutshell,
we need to check and extend Section 6 of the Hoobhoy, Jaffe, Manohar
original paper (that really dates back awhile!).

We already worked out the amps. for our Angular Momentum sum rule paper.
Our formalism is sketched out in a short publication

http://prd.aps.org/abstract/PRD/v86/i3/e036008

(we are in the process of writing a longer paper).
We are now going going to extend this and explain what is needed for b_1
(H_5 in the GPD formalism) i.e. define the relevant observables (what type
of asymmetries) from the amps.

I have an extra question on whether you would consider detecting an extra
photon (and test the AM sum rule ;-) ), but this is a side remark for now.

I am also attaching the talk I gave in Shanghai last Fall.

Please let me know if there in any other question.

Looking forward to working some more on all this!
Simonetta

On Thu, 14 Mar 2013 19:33:06 -0400
 "O. A. Rondon" <or at virginia.edu> wrote:
>Dear Simonetta and Kunal,
>
>It was great to meet with you two and Dustin today, to discuss how to
>measure b1. Here are some items that you should find useful.
>
>b1 wiki
>https://hallcweb.jlab.org/wiki/index.php/B1
>
>The talk slides I showed at the meeting are under "Relevant Publications"
>
>The email attachment from Bob Jaffe replying to our question about sec.
>6 of his paper with Hoodbhoy and Manohar is on my b1 folder on twist
>https://twist.phys.virginia.edu/~or/b1/
>
>look for "b1-b2.pdf", but feel free to explore any and all items there.
>Our question, as formulated by Patricia, and Jaffe's reply are at the
>end of this message.
>
>There is a b1 mailing list that you can subscribe to, see the wiki. I'm
>copying this message to the mailing list. All interested collaborators
>should subscribe, and future mailings be done preferably using the list.
>
>Thank you and looking forward to our collaboration on this project,
>
>Oscar
>
>> --------------
>> On Nov 30, 2010, at 5:16 PM, Robert L. Jaffe wrote:
>>
>>> Dear Patricia,
>>>
>>> Attached is a .tex/.pdf file that addresses your question.  There
>> certainly is a difference between a state polarized transverse to the
>> beam and one polarized longitudinal to it.  I hope the notes are useful.
>>> Bob
>>> <b1-b2.pdf>
>>> Robert L. Jaffe
>>> Morningstar Professor of Physics and MacVicar Faculty Fellow
>>
>>
>>> On Nov 30, 2010, at 12:47 PM, Patricia SOLVIGNON wrote:
>>>
>>>> Dear Bob.
>>>>
>>>> Because I have been used to think in the case of spin-1/2 and the
>> double-polarization
>>>> measurement, I am still a bit confused about the right measurement
>> method of b1. From
>>>> section 6 of your paper with P. Hoodbhoy and A. Manohar (Nuc. Phys
>> B312, 571(1989)),
>>>> the variable H appears in both sigma_para and sigma_perp.
>>>> My understanding is that H (= the target spin projection along the
>> beam) is equal to +/-1
>>>> in the longitudinal case and to 0 in the transverse case. If that is
>> true:
>>>> sigma_para  = sigma_perp = kin_fact *sigma_mott*(F1 - 1/3 b1)
>>>>
>>>> and we need either to perform a measurement of F1d from an
>> unpolarized target at the
>>>> same kinematics as for the measurement on the longitudinally
>> polarized target or use a
>>>> model from F1d with the uncertainty that comes along.
>>>>
>>>> The submission of the proposal is due tomorrow so I want to make sure
>> I understood the
>>>> formalism for a measurement of b1.
>>>>
>>>> Thank you for your help.
>>>>
>>>> Best regards,
>>>> Patricia
>
>
>
>
>
>
>
>

**************************************************************
**************************************************************
Prof. Simonetta Liuti                     telephone (434) 982-2087
Department of Physics               FAX       (434) 924-4576
University of Virginia              home      (434) 973 9593
382 McCormick Rd.
PO Box 400714
Charlottesville, VA 22904-4714
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