[d2n-analysis-talk] Neutron extraction for A1

[Diana Parno]

Hello all,

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