The Dilaton Potential and Lattice Data

Lattice studies of a certain class of confining gauge
theories indicate the presence of an anomalously light scalar in the
spectrum of composites. Gauge theories in this class are chosen to have a
light fermion count lying just below the threshold value for entry into
the conformal window. In this talk, I will discuss recent work in which
this light scalar is interpreted as a dilaton and a simple EFT description
for it is studied and used to analyse recent lattice results. In this
work, we adopt a simple form for the dilaton potential in the EFT, which
interpolates among earlier proposals. It describes departures from
conformal symmetry, by the insertion of a single operator at leading order
in the EFT. Using the lattice measurements, we extract model parameter
values, including those that characterise the scalar potential. The
results suggest that the EFT provides a good fit to the data, and include
the possibility that the conformal deformation is clearly non-marginal.