University of Cambridge > Talks.cam > DAMTP Friday GR Seminar > Chameleon-photon mixing in a primordial magnetic field

Chameleon-photon mixing in a primordial magnetic field

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If you have a question about this talk, please contact James Fergusson.

The chameleon scalar field has been proposed as a possible candidate for dark energy. The chameleon mechanism, whereby the mass of the scalar depends on the surrounding matter density, allows the scalar field to have a strong coupling to normal matter and yet still evade fifth-force constraints. An extension of the original chameleon model includes a direct coupling between the chameleon and electromagnetic field. This generates mixing between chameleons and photons in the presence of a background magnetic field. Here we consider the modification to the average intensity of the cosmic microwave background as a result of chameleon-photon mixing in a primordial magnetic field. We find that comparison of these predictions to precision measurements of the CMB black-body spectrum places strong constraints on the combined magnitude of the primordial magnetic field and chameleon-photon coupling strength.

This talk is part of the DAMTP Friday GR Seminar series.

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