[d2n-analysis-talk] Neutron extraction for A1

[Brad Sawatzky]

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