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Theory Center Seminar<br>
Wed., April 2, 2014<br>
2:00 p.m. (coffee at 1:45 p.m.)<br>
CEBAF Center, Room F113<br>
<br>
Aron M. Bernstein <br>
MIT <br>
<br>
<b>Experimental Tests of QCD Symmetries with Pions: Entering A New
Era </b><br>
<br>
We are entering a new era in which we can test confinement scale QCD
in some well chosen reactions<br>
such as pi-pi and pi-N scattering, pion properties, and
electromagnetic pion production from the nucleon. <br>
Based on the spontaneous breaking of chiral symmetry, chiral
perturbation theory (ChPT) is believed to <br>
approximate confinement scale QCD as demonstrated by increasingly
accurate lattice calculations, particularly<br>
in pi-pi scattering. Following a brief review of this field,
emphasis will be given to recent, Increasingly accurate, <br>
experiments in electromagnetic pion production experiments from the
proton performed at Mainz and JLab; <br>
these test ChPT calculations and their energy region of validity.
The connection between electromagnetic pion<br>
production, pi-N scattering, and quark mass effects will be
presented.
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