[d2n-analysis-talk] A Fit to the Ratio of Unpolarized Structure Functions F_2

[David Flay]

On Tue, Oct 26, 2010 at 9:46 PM, David Flay <flay at jlab.org> wrote:

> Hi all,
>
> So I've spent some time coming up with a modest fit to parameterize
> R^{np}, which will influence how we estimate R = F_2^n/F_2^{3He}.
>
> Attached is my (initial) result.  I initially wanted to go with a
> polynomial fit, but I was able to achieve a \chi^2/ndf ~ 1 using the form
> I display in the plot -- a linear combination of a gaussian and an
> exponential.  The reasoning for the gaussian was to try to get a nice fit
> to the region for x ~ 0.1, where we see R^{np} ~ 1, and from there on out,
> I wanted the exponential to take care of the rest (that is, after x ~
> 0.22, and hence why p_1 = 0.22).  This didn't necessarily work, but
> because the \chi^2/ndf came out pretty good, I decided to keep this form.
> The parameters p_0, p_2, and p_3 were arbitrary.
>
>
I just realized my choice of p_1 = 0.22 should've been 0.1, as 0.22 centers
the gaussian portion on the wrong spot... changing p_1 to 0.1 doesn't change
the fit by much at all.  In any case, the fit I display is pretty good for
an estimation.


-- 
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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://www.jlab.org/%7Eflay>
             http://quarks.temple.edu
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