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Journal Article

#### How stable is the photon?

##### Locator

http://link.aps.org/doi/10.1103/PhysRevLett.111.021801

(Publisher version)

##### Fulltext (public)

1304.2821.pdf

(Preprint), 165KB

##### Supplementary Material (public)

There is no public supplementary material available

##### Citation

Heeck, J. (2013). How stable is the photon?* Physical Review
Letters,* *111*(02): 021801, pp. 1-4. doi:10.1103/PhysRevLett.111.021801.

Cite as: http://hdl.handle.net/11858/00-001M-0000-0014-13ED-4

##### 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 10

^{15}.