We discuss bound state excitation in models where wave function collapse is a physical process. Consequences of a feasible photon counting experiment are spelled out, were an upper limit to be found on the rate of anomalous photon emission from solid matter that is better than 1 photon/sec cc. It is also pointed out that experiments already performed, which give an upper bound on the rate of nucleon decay, can have significant consequences for such models. We show how these experimental results could be considered to rule out the original version of the collapse models, and support a version in which the rate of collapse is proportional to the mass, indicative of a gravitational mechanism.

• Received 16 August 1993

DOI:https://doi.org/10.1103/PhysRevLett.73.1