PARTICLE PHYSICS BOUNDS FROM THE HULSE-TAYLOR BINARY

The orbital period of the binary pulsar PSR 1913+16 has been observed to decrease at the rate of 2.40x10(-12) s/s which agrees with the pred iction of the quadropole formula for gravitational radiation to within one percent. The decrease in orbital period may also occur by radiati on of other massless particles such as scalars and pseudoscalar Nambu- Goldstone bosons. Assuming that this energy loss is less than one perc ent of the gravitational radiation, we dan establish bounds on couplin gs of these particles to nucleons; For a scalar nucleon coupling of th e form <g(s) phi(psi)over bar psi> we find that g(s)<3x10(-19). From t he radiation loss of massless Goldstone bosons we establish the upper bound theta g(s)<10(-16) on the QCD vacuum angle theta and the pseudos calar nucleon coupling constant g(p).