DETERMINATION OF PSEUDO-GOLDSTONE-BOSON PHOTON COUPLING BY THE DIFFERENTIAL TIME-DELAY OF PULSAR SIGNALS

Pseudo Goldstone bosons couple with photons through a P and T violating interaction of the form L(J)=g(agammagamma)aFF. Strong magnetic fields in rotating compact stars induce a nonzero E.B outside the stellar surface which acts as a source for the pseudoscalar field. Pulsar signals propagating through this pseudoscalar ''hair'' suffer a differential time lag between the left and the right circularly polarized modes because of the P and T violating pseudoscalar-boson-photon interaction. Determination of this time lag up to a microsecond accuracy can lead to a measurement of (or rule out) pseudo-Goldstone-boson-photon coupling up to g(agammagamma) less-than-or-equal-to 2.0 x 10(-11) GeV-1.