[d2n-analysis-talk] Ratio of Unpolarized Structure Functions

[David Flay]

Hi all,

I've been working on getting a parameterization of the quantity R^{np}(x).

My plan is: First, we plot the data as a function of x (Xiaochao's plot,
with some updated data sets as well that I have found), then determine a
fitting function f(x) that describes the data well.

>From there, we would have:

R^{np}(x) = f(x).

>From this, we can determine for a given value of x what R^{np} may be
approximated to be.

>From there, we can calculate the R we are interested in:

R = F_2^{n}/F_2^{3He} \approx F_2^{n}/[F_2^{n} + 2F_2^{p}] = R^{np}/[
R^{np} + 2]

Notice the last equality: in my most recent talk, there is a mistake --
since R^{np} = F_2^n/F_2^p, this implies F_2^n = R^{np}F_2^p.  My equation
I showed gives (incorrectly) F_2^p = R^{np}F_2^n.
Subsequently, this implies our error bars will get worse, based upon a
quick calculation:

at x = 0.6 => R^{np} ~ 0.4 => R = 0.4/(0.4 + 2) ~ 0.167

This clearly will give a larger error bar on A_1^n.

Our best case scenario would yield R ~ 0.28 (at x ~ 0.2)

I'll have an updated discussion on both the parameterization of R^{np}(x)
and the resulting A_1^n within the end of week...


Dave

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David Flay
Physics Department
Temple University
Philadelphia, PA 19122

office: Barton Hall, BA319
phone: (215) 204-1331

e-mail: flay at jlab.org
            flay at temple.edu

website: http://www.jlab.org/~flay
              http://quarks.temple.edu
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