Theory 05/Physics, Cosmos & Matter /Particle physics
Dark Photon Lines Are Broadened
A line's width is treated as a property of the particle. It may be a property of the gas in front of it.
The width of a dark photon absorption line is set by plasma broadening along the line of sight rather than by the dark photon mass, so line width measures the electron column and can separate a detection from a noise feature.
01The evidence
Dark photon searches report candidate lines with widths that are not resolved, and the candidates have not survived reanalysis.
02The tension
Search analyses fit a narrow line and treat width as instrumental. A broadened line would be rejected as inconsistent with a particle, which biases the search against real signals.
03The mechanism
A dark photon converts in a plasma, and the conversion resonance depends on the local plasma frequency. Along a line of sight, the resonance is smeared by density variation.
That makes the observed line a convolution, and predicts width should track the dispersion measure of the same sightline.
04What this is not
Those searches assume a particle width. This assumes plasma broadening, which predicts a correlation with the medium.
05Predictions
- P1Line width should correlate with dispersion measure.
- P2Broad candidates should be re-examined.
- P3Width should vary between sightlines.
06Refutation
Widths inconsistent with plasma columns would favour an intrinsic line.
07What it changes
It would change how dark photon candidates are filtered.