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<p><font face="Calibri">Theory Center Seminar<br>
Monday, March 5, 2018<br>
1:00 p.m. (coffee at 12:45 p.m.)<br>
CEBAF Center, Room L102</font></p>
<font face="Calibri">Andreas Metz<br>
Temple University<font color="#0f61c8"><br>
</font><br>
<b>Twist-3 GPDs in Deeply Virtual Compton Scattering<br>
<br>
</b><font size="2">The sub-leading power of the scattering
amplitude for deeply-virtual Compton scattering (DVCS) off </font><br>
<font size="2">the nucleon contains leading-twist and twist-3
generalized parton distributions (GPDs). We point out</font><br>
<font size="2"> that in DVCS, at twist-3 accuracy, one cannot
address any individual quark twist-3 GPD. Accessible are </font><br>
<font size="2">exclusively linear combinations involving both
vector and axial-vector twist-3 GPDs. This implies, in </font><br>
<font size="2">particular, that in DVCS there is no direct
access to the (kinetic) orbital angular momentum of quarks </font><br>
<font size="2">through twist-3 GPDs. Moreover, using the
quark-target model, we find that twist-3 GPDs can be </font><br>
<font size="2"> discontinuous. The discontinuities however
vanish in the DVCS amplitude, which further supports the </font><br>
<font size="2">hypothesis of factorization at twist-3 accuracy.<br>
<br>
</font><font color="#0f61c8"><br>
</font>The bluejeans link for the remote connection is <a
href="https://bluejeans.com/335716039">https://bluejeans.com/335716039</a><br>
</font><font color="#0f61c8"><br>
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