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Theory Center Seminar<br>
Monday, Dec. 14, 2015<br>
1:00 p.m. (coffee at 12:45 p.m.)<br>
CEBAF Center, Room L102<br>
<br>
Derek Horkel<br>
University of Washington<br>
<br>
<b>Phase Structure of Lattice QCD with Wilson and Twisted-Mass
Fermions Including Isospin Breaking</b><br>
<br>
As the precision frontier of particle physics continues to develop,
the field of lattice QCD has risen to the challenge. <br>
Modern lattice simulations, have increasingly included light
non-degenerate up and down quark masses and <br>
electromagnetism. Previously answered questions about the vacuum
structure of QCD on the lattice must be <br>
reexamined when these isospin breaking effects are included. If not
careful, lattice practitioners may simulate <br>
in non-physical phases which cannot be extrapolated to the continuum
limit. Using chiral perturbation theory, <br>
I will discuss where these non-physical phases can arise for Wilson
and twisted mass fermions. I will also explain<br>
some of the complications which arise when tuning the up and down
twisted quark masses to their critical values<br>
in the presence of electromagnetism.<br>
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