UPDATING NUCLEOSYNTHESIS BOUNDS ON JORDAN-BRANS-DICKE THEORIES OF GRAVITY

Nucleosynthesis bounds on Jordan-Brans-Dicke theories of gravity are updated using improved determinations of He-4, D + He-3 and Li-7 primordial abundances and neutron life-time. We find, for N(nu) = 3 and most of the allowed OMEGA(0)h0(2) range, stronger bounds than those obtained from post-newtonian experiments, \omega\ > 250 (2-sigma). In particular at 2-sigma level, omega > 380 (440) for OMEGA(0)h0(2) = 0.25 (1). Furthermore, it is suggested that GR predictions with N(nu) = 3 are hardly consistent with nucleosynthesis observations at 90% CL, while GR with N(nu) = 2 seems to accommodate better the observations.