<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
</head>
<body bgcolor="#ffffff" text="#000000">
<font face="Times New Roman, Times, serif">Please RSVP to: <a
class="moz-txt-link-abbreviated" href="mailto:lcarlson@jlab.org">lcarlson@jlab.org</a>
by COB on April 19, 2011.</font><br>
<br>
<div align="center"><span
style="font-family: "Times New Roman","serif";"></span>
<span style="font-family: "Times New Roman","serif";">Wednesday, April
20,
2011</span><br>
<span style="font-family: "Times New Roman","serif";"><b><span
style="color: red;">***CC F113***</span></b></span><br>
<span style="font-family: "Times New Roman","serif";"><span
style="color: black;">12:00-1:00pm</span></span><br>
<span style="font-family: "Times New Roman","serif";"></span><br>
<span style="font-family: "Times New Roman","serif";"></span><span
style="font-size: 14.5pt; font-family: "Times","serif";">Nucleon
Electromagnetic Form Factors </span><br>
<span style="font-size: 14.5pt; font-family: "Times","serif";">at Low </span><span
style="font-size: 14.5pt; font-family: "Times","serif";">Q</span><sup><span
style="font-size: 10pt; font-family: "Times","serif";">2</span></sup><span
style="font-size: 10pt; font-family: "Times","serif";">
</span><span style="font-size: 14.5pt; font-family: "Times","serif";">and
the Proton Size Puzzle<o:p></o:p></span>
<span style="font-family: "Times New Roman","serif";"></span><br>
<span style="font-family: "Times New Roman","serif";"><b>Xiaohui Zhan</b></span><br>
<span style="font-family: "Times New Roman","serif";"></span><span
style="font-family: "Times","serif";">Argonne National Laboratory</span><br>
<span style="font-family: "Times","serif";"></span></div>
<span style="font-family: "Times","serif";"><br>
</span>
<span style="font-family: "Times New Roman","serif";"><b>Abstract:<br>
</b></span>
<p class="MsoNormal"
style="margin: 0in 153pt 0.0001pt 0in; line-height: normal;"><span
style="font-family: "Times","serif";">The nucleon electromagnetic form
factors are fundamental quantities
which relate to the nucleon charge and magnetization distributions
within the
nucleon, and have been extensively measured through electron scattering
in the
last few decades. While the measurements on the proton form factors at
large
momentum transfer have provided information on the fine details of the
proton
structure and raised intense studies on the two-photon exchange effect,
recent
high precision polarization and cross section measurements in low </span><span
style="font-family: "Times","serif";">Q</span><sup><span
style="font-family: "Times","serif";">2</span></sup><span
style="font-family: "Times","serif";"> </span><span
style="font-family: "Times","serif";">region have
shown that the long-range structure is not as simple as previously
believed.
New value of the proton RMS charge radius is extracted based on updated
world </span><i style=""><span style="font-family: "Times","serif";">ep</span></i><span
style="font-family: "Times","serif";"> </span><span
style="font-family: "Times","serif";">scattering data at low </span><span
style="font-family: "Times","serif";">Q</span><sup><span
style="font-family: "Times","serif";">2</span></sup><span
style="font-family: "Times","serif";">, and the result
is consistent with other measurements based on electron-proton
interactions. The
combined results are 7.7</span><span
style="font-family: "Times","serif";">σ </span><span
style="font-family: "Times","serif";">above the recent extraction from
muonic hydrogen
Lamb shift. This significant difference suggests either a problem with
the
extraction from muonic hydrogen, or else that something is missing in
our
understanding of the electromagnetic interaction<br>
</span></p>
<p class="MsoNormal"
style="margin: 0in 153pt 0.0001pt 0in; line-height: normal;"><br>
</p>
<font face="Times New Roman">For current events and general information
please visit our wiki page:<br>
<a href="https://gspda.jlab.org/wiki/index.php/Main_Page">https://gspda.jlab.org/wiki/index.php/Main_Page</a></font>
<pre class="moz-signature" cols="72">
</pre>
</body>
</html>