D. Lohiya et M. Sethi, A programme for a problem-free cosmology within the framework of a rich class of scalar-tensor theories, CLASS QUANT, 16(5), 1999, pp. 1545-1563
A search for a problem-free cosmology within the framework of an effective
nonminimally coupled scalar-tensor theory is suggested. With an appropriate
choice of couplings in variants of a Lee-Wick model (as also in a model su
pporting Q-ball solutions), non-topological solutions (NTSs), varying in si
ze up to 10 kpc to 1 Mpc can exist. We explore the properties of a 'toy' Mi
lne model containing a distribution of NTS domains. The interior of these d
omains would be regions where effective gravitational effects would be indi
stinguishable from those expected in standard Einstein theory. For a large
class of non-minimal coupling terms and the scalar effective potential, the
effective cosmological constant vanishes identically. The model passes cla
ssical cosmological tests and we describe reasons to expect it to fare well
as regards nucleosynthesis and structure formation.