Gravitational Collider Physics via Pulsar–Black Hole Binaries

We propose to use pulsar–black hole binaries as a probe of gravitational collider physics. Induced by the gravitation of the pulsar, the atomic transitions of the boson cloud around the black hole backreact on the orbital motion. This leads to the deviation of the binary period decrease from that predicted by general relativity, which can be directly probed by the Rømer delay of pulsar times of arrival. The sensitivity and accuracy of this approach are estimated for two typical atomic transitions. It is shown that once the transitions happen within the observable window, the pulsar-timing accuracy is almost always sufficient to capture the resonance phenomenon.