[b1_ana] Fwd: http://arxiv.org/abs/1311.4561

[O. A. Rondon]

Hi Karl and b1_analysis,

To make the b1 data and Gerry's models equally visible at any x, I've
plotted xb1 vs x for b1(HERMES) (statistical and systematic errors added
in quadrature), and for model b1(j) = b1^{pi}(j) + b1^{6q}, with j = 1
to 3, per Table 1 of the arKiv draft. I joined the model points with
just some cubic splines, to see the trends.

Model b1^{pi}(j=1) (blue solid curve) agrees best with the low x data,
and all models agree with HERMES b1(x=0.452), but the HERMES errors
can't quite distinguish between b1^{pi} models. And taking the
difference between models as an estimate of the model errors, it looks
like they are only somewhat smaller than the current data errors, so
it's hard to say if b1 will increase or decrease as it goes to x=0, or
whether it would cross zero near x~0.2 or near ~0.4.

The blue curve has a node at a fairly low value of x < ~0.25, which
looks similar to the nodes of Kumano's  parameterizations, which do
follow the data's decreasing trend at low x.

Also, I see that in our proposal's figures, the node of the OPEP b1 was
at  x ~ 0.1 or less, but now they are always positive up to somewhere
between x ~ 0.13 and 0.25 or higher.

It would be very useful if Gerry could provide some estimate of the
model uncertainties for all components (three pion models and the 6
quark part), to compare with our projected errors, to see if our
measurement could distinguish between models. At the moment, it looks
like the most it could do is to confirm whether b1 < 0 for x > ~ 0.3.

Cheers,

Oscar

Karl Slifer wrote:
> ---------- Forwarded message ----------
> From: Gerald Miller <miller at phys.washington.edu>
> Date: Tue, Nov 19, 2013 at 9:09 PM
> Subject: http://arxiv.org/abs/1311.4561
> To: Patricia SOLVIGNON <solvigno at jlab.org>, Karl Slifer <slifer at jlab.org>
> 
> 
> Dear Karl and Patricia
> 
> I have posted my paper at
> http://arxiv.org/abs/1311.4561
> 
> I found a hidden color mechanism that can account for the Hermes high x
> point, and this combined with pion effects leads to a reproduction of their
> data set. I really look forward to your experiment.
> 
> The abstract reads
> 
> The b1 structure function is an observable feature of a spin-1 system
> sensitive to non-nucleonic components of the target nuclear wave function.
> The contributions of exchanged pions in the deuteron are estimated and
> found to be of measurable size for small values of x. A simple model for a
> hidden-color, six-quark configurations (with~ 0.15% probability to exist in
> the deuteron) is proposed and found to give substantial contributions for
> values of x>0.2. Good agreement with Hermes data is obtained. Predictions
> are made for an upcoming JLab experiment. The Close & Kumano sum rule is
> investigated and found to be a useful guide to understanding various
> possible effects that may contribute.
> 
> Best
> Jerry
> 
> 
> 
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