Particle level screening of scalar forces in 1+1 dimensions
  We investigate how non-linear scalar field theories respond to point sources.
Taking the symmetron as a specific example of such a theory, we solve the
non-linear equation of motion in one spatial dimension for (i) an isolated
point source and (ii) two identical point sources with arbitrary separation. We
find that the mass of a single point source can be screened by the symmetron
field, provided that its mass is above a critical value. We find that two point
sources behave as independent, isolated sources when the separation between
them is large, but, when their separation is smaller than the symmetron's
Compton wavelength, they behave much like a single point source with the same
total mass. Finally, we explore closely related behavior in a toy Higgs-Yukawa
model, and find indications that the maximum fermion mass that can be generated
consistently via a Yukawa coupling to the Higgs in 1+1 dimensions is roughly
the mass of the Higgs itself, with potentially intriguing implications for the
hierarchy problem.
