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<p><font face="Times New Roman, Times, serif">Theory Center Seminar<br>
Monday, Nov. 21, 2016<br>
<b>2:45 p.m. (coffee at 2:30 p.m.)</b><br>
CEBAF Center, Room F324/325<br>
<br>
Dmitrij Siemens<br>
Bochum University</font><font face="Times New Roman, Times,
serif"><b><font><span style="font-size: 15px;"><br>
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<div><font face="Times New Roman, Times, serif"><b><font><span
style="font-size: 15px;"><br style="font-size: 13px;">
</span></font></b><b><span style="font-size: 15px;">Pion-Nucleon
Scattering in Chiral Perturbation Theory</span></b><br
style="font-size: 13px;">
<font style="font-size: 14px;" color="#0f61c8" size="2"><br>
</font></font></div>
<div><font face="Times New Roman, Times, serif">Elastic pion-nucleon
scattering is analyzed in the framework of chiral perturbation
theory at<br>
</font></div>
<font face="Times New Roman, Times, serif">the full one-loop order
with explicit Delta degrees of freedom. The analysis is performed
in<br>
the small scale expansion within the heavy baryon and a covariant
approach based on the extended<br>
on mass-shell renormalization scheme. The pertinent low-energy
constants contributing to the<br>
pion-nucleon scattering amplitude are extracted from fits to
experimental scattering data as<br>
well as subthreshold parameters. A novel approach to estimate the
theoretical uncertainty based<br>
on the truncation of the chiral series is employed in the fitting
procedure. The obtained results<br>
for the various pion-nucleon scattering observables are presented
and discussed.</font>
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