[d2n-analysis-talk] Neutron extraction for A1

[Diana Parno]

Brad,

Thanks for the kick. I've emailed Wally. I'll keep you posted.


Best,
Diana

On Sep 29, 2011, at 8:56 PM, Brad Sawatzky wrote:

> Just a ping on the neutron extraction stuff.  I can volunteer to
> follow-up locally if that would work best, but I don't want to step on
> toes if this is in progress.
>
> -- Brad
>
> On Thu, 15 Sep 2011, Brad Sawatzky wrote:
>
>> Hi Diana, Gregg,
>>
>> Any chance you have heard from Wally on the 3He to neutron  
>> corrections
>> discussed below?
>>
>> My notes from June suggest that he might have something for us around
>> September.  Odds are this fell to the bottom of his todo list, but  
>> I'd
>> like to follow up on it and get a feel for the status.
>>
>> Diana's email from June 10 suggests there may be an email from Wally
>> with some comments on the more general, x-dependent method he and
>> Kulagin published in 2008  (second bullet in Diana's email below).
>> If so, can that note be cc'd to the list for reference?
>>
>> -- Brad
>>
>> On Wed, 15 Jun 2011, Brad Sawatzky wrote:
>>
>>> Just a couple comments on issues to keep in mind.
>>>
>>> Note that we'll want to have the information available to correct  
>>> the
>>> g_1(x,Q2), g_2(x,Q2) points individually, _and_ to be able to  
>>> correct
>>> the d2(Q2) term as a 'unit'.  That is we'll want to be able to  
>>> apply a
>>> correction to the already-integrated d2 matrix element, rather than
>>> correct the individual integrand points prior to integration.
>>>
>>> (We'll probably do it both ways, but the latter method should  
>>> result in
>>> a smaller systematic uncertainty for the final d2n value.)
>>>
>>> -- Brad
>>>
>>> On Fri, 10 Jun 2011, Diana Parno wrote:
>>>
>>>> Wally Melnitchouk and I met yesterday afternoon and had a very
>>>> productive discussion about going from 3He to the neutron. Here's  
>>>> the
>>>> executive summary:
>>>>
>>>> - The Bissey et al method (which I presented in last week's  
>>>> analysis
>>>> meeting) assumes no x-dependence (so, it's not quite as  
>>>> "complete" as
>>>> the title describes!). This is probably safe for our DIS points but
>>>> definitely not for our resonance points.
>>>>
>>>> - Wally recommends the more general, x-dependent method in  
>>>> Kulagin and
>>>> Melnitchouk, PRC78 065203 (2008). Unfortunately, they've only  
>>>> worked
>>>> out this method for g_1 and g_2 on the neutron, not on the
>>>> asymmetries. He thinks that the extension to A_1 and A_2 would be
>>>> relatively straightforward and a useful problem, and predicts  
>>>> that he
>>>> should have something for us on the general time scale of three  
>>>> months
>>>> (see email). He's excited at the prospect of experimental  
>>>> interest in
>>>> the method described in the 2008 paper. From our end, I think a few
>>>> months is quite reasonable and will give us time to pursue the  
>>>> 5.9-GeV
>>>> dataset, pair-production corrections, radiative corrections, etc.
>>>>
>>>> - He agrees with my worry about Bissey et al's assumption that A2  
>>>> is
>>>> close to zero, but we think that (for a first look at the DIS data
>>>> points), their equation should be very easily extensible to g1/F1
>>>> without having to make that assumption. I think the math on that is
>>>> relatively simple and I'll work on it next week.
>>>>
>>>> - He doesn't think that anti-shadowing is a big deal for our low-x
>>>> point -- probably a few percent. On the other hand, we're worrying
>>>> about a few-percent EMC effect, so perhaps it's worth some study.  
>>>> His
>>>> own work includes the delta isobar but not shadowing/anti- 
>>>> shadowing.
>>>>
>>>> Brad, Matt, and Dave: I enjoyed seeing you at the Hall A meeting!  
>>>> Hope
>>>> we'll cross paths in person some time again soon. It was a very
>>>> productive and interesting couple of days.
>>>>
>>>> Enjoy your weekends,
>>>> Diana
> -- 
> Brad Sawatzky, PhD <brads at jlab.org>  -<>-  Jefferson Lab / Hall C /  
> C111
> Ph: 757-269-5947  -<>-  Fax: 757-269-5235  -<>- Pager: brads-page at jlab.org
> The most exciting phrase to hear in science, the one that heralds new
>  discoveries, is not "Eureka!" but "That's funny..."   -- Isaac Asimov