Speaker
Description
We are about to enter a revolutionary new period in our understanding of the
charged pion form factor, $F_{\pi}$. As the lightest meson, it is the particle
responsible for the long-range character of the $N-N$ interaction that binds
the atomic nucleus. Furthermore, if QCD were chirally symmetric, the pion
would be massless. But chiral symmetry is dynamically broken by quark-gluon
interactions and the inclusion of light quark masses, giving the pion (and
ultimately all other hadrons) significant mass. Thus, the pion is central to
many of the key questions of strong-interaction physics. There have been
enormous advances in the last several years. Recent $F_{\pi}$ calculations
have shed much light on the links between dynamical chiral symmetry
breaking, quark confinement and the generation of hadron mass. There have also
been great advances in lattice QCD calculations, providing for the first time
reliable predictions of $F_{\pi}$ in the $1\lt Q^2\lt 6$ GeV$^2$ region.
Experimentally, there is also much promise. The measurement of $F_{\pi}$ is
challenging, as it must make use of the dominance of the nucleon's virtual pion
cloud in pion electroproduction at low $-t$. With the recent completion of the
Jefferson Lab Hall C apparatus, we will (for the first time since the
pioneering Cornel data of the 1970's) be able to acquire the high quality data
needed to provide rigorous tests of the recent theoretical developments. The
new instrumentation will nearly triple the momentum transfer over which
$F_{\pi}$ is accurately known, probing the regime in which QCD begins to
transition from large- to short-distance behavior. It will be an exciting time,
and my talk will provide a glimpse into the path ahead.
(*) Supported by NSERC SAPIN-2016-00031
