[B1] b1d

[O. A. Rondon]

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