  The Neel magnetization of 2+1 D antiferromagnets is composed of quark-like
spin 1/2 constituents, the spinons, as follows from the CP^1 mapping. These
quark spinons are confined in both the Neel ordered phase and quantum
paramagnetic phases. The confinement in the quantum paramagnetic phase is
understood as arising from quantum tunneling events, instantons or hedgehog
monopole events. In the present article, we study the approach to the quantum
critical point, where the quantum paramagnetic phase ceases to exist. We find
that irrespective of the intrinsic spin of the antiferromagnet, instanton
events disappear at the deconfined critical point because instanton tunelling
becomes infinitely costly and have zero probability at the quantum critical
point. Berry phase terms relevant to the paramagnetic phase vanish at the
quantum critical point, but make the confinement length scale diverge more
strongly for half-integer spins, next strongest for odd integer spins, and
weakest for even integer spins. There is an emergent photon at the deconfined
critical point, but the "semimetallic'' nature of critical spinons screens such
photon making it irrelevant to long distance physics and the deconfined spinons
are strictly free particles. A unique prediction of having critical free
spinons is an anomalous exponent eta for the susceptibility exactly equal to
one. Experimentally measurable response functions are calculated from the
deconfined spinon criticality.
