They would break apart into their neutron protron and electron make up.
They would split into their component quarks. This is the basis by which CERN operates.
and leptons! ┌(・。・)┘♪└(・。・)┐♪┌(・。・)┘
They make a new star
The sh*t would hit the fan.
not light speed but when close (~99.99999999%) they collide and make anti-protons, protons, muons, tau particles, neutrinos, bosons, higgs, delta(++) but not for long