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Theory Center Seminar<br>
Fri., Jan. 29, 2016<br>
10:00 a.m. (coffee at 9:45 a.m.)<br>
CEBAF Center, Room L102 <br>
<br>
Chris Monahan <br>
Rutgers University<br>
<br>
<b>Towards a First Principles Picture of the Proton </b><br>
<br>
The direct calculation of nucleon structure from first principles is
an unsolved challenge <br>
for quantum chromodynamics (QCD). In particular, parton distribution
functions (PDFs), <br>
which capture the longitudinal momentum structure of fast-moving
nucleons, are defined<br>
on the light cone and are not directly accessible in Euclidean
lattice QCD. To circumvent this<br>
problem, moments of PDFs can be expressed in terms of matrix
elements of local operators, <br>
but these operators suffer from power-divergent mixing, which stems
from the hypercubic <br>
symmetry of the lattice regulator. I will introduce a new method
that suppresses this power<br>
divergent mixing, at the expense of introducing a new physical scale
in the continuum. I will <br>
highlight the role that this method plays in ab initio calculations
of PDFs and outline a program<br>
for the direct determination of nucleon structure on the lattice.
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