Abstract
Yes, the photon. While a nonzero photon mass has been under experimental and theoretical study for years, the possible implication of a finite photon lifetime lacks discussion. The tight experimental upper bound of the photon mass restricts the kinematically allowed final states of photon decay to the lightest neutrino and/or particles beyond the standard model. We discuss the modifications of the well-measured cosmic microwave background spectrum of free streaming photons due to photon mass and lifetime and obtain model-independent constraints on both parameters—most importantly a lower direct bound of 3 yr on the photon lifetime, should the photon mass be at its conservative upper limit. In that case, the lifetime of microwave photons will be time-dilated by a factor order .
- Received 17 April 2013
DOI:https://doi.org/10.1103/PhysRevLett.111.021801
© 2013 American Physical Society
Synopsis
Constraining the Photon Lifetime
Published 11 July 2013
Photons could conceivably decay, but new analysis of the cosmic microwave background shows that a visible wavelength photon is stable for at least years.
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