- The paper demonstrates that hidden photons produced via kinetic mixing yield a resonant abundance nearly independent of their mass.
- The study employs detailed plasma effect analyses to show that photon decay into three photons constrains their dominance as dark matter.
- The research suggests alternative production mechanisms may enhance hidden photon contributions, motivating further experimental and theoretical studies.
Massive Hidden Photons as Lukewarm Dark Matter
The paper "Massive Hidden Photons as Lukewarm Dark Matter" by Javier Redondo and Marieke Postma explores the potential role of hidden photons as a candidate for dark matter, within the mass range of keV to MeV. The exploration revolves primarily around the interaction of a hidden sector U(1) gauge boson, referred to as a hidden photon (HP), with the standard model (SM) sector through kinetic mixing with the photon. This mechanism is scrutinized within a comprehensive framework that encompasses relevant plasma effects impacting the photon's self-energy. These effects culminate in a resonant yield that is nearly invariant with respect to the HP mass.
The investigation unveils that hidden photons can decay into three photons, with significant production occurring in stars if their mass is sufficiently low. Various constraints emanate from cosmic photon backgrounds and stellar evolution observations, which restrict the hidden photon to contributing only subdominantly to dark matter. The paper posits alternative production mechanisms beyond kinetic mixing could circumvent these constraints, opening avenues for hidden photons to play a more substantial role in dark matter composition.
Numerical Results and Contradictory Claims
The numerical analysis is rather compelling, particularly in how it tackles the relic abundance calculations. The paper integrates plasma effects into the self-energy of photons, offering a novel perspective where hidden photon production is dominated by a resonance phase—specifically occurring when the thermally induced mass of a photon equals that of the hidden photon. Interestingly, the yield from this resonance is substantially independent of the hidden photon's mass.
Moreover, a striking claim within the paper asserts that under the regime where kinetic mixing predominates as the production mechanism, hidden photons cannot constitute the bulk of cold dark matter. This is attributed to the fact that for a hidden photon mass exceeding MeV, decay into electron-positron pairs becomes feasible, which challenges the stability requisite for dark matter, considering the age of the universe.
Implications and Future Projections
The findings bear significant implications for both theoretical and practical dimensions of particle physics and astrophysics. The constraints imposed by stellar evolution and cosmic backgrounds suggest stringent limitations on hidden photons emerging as dominant dark matter constituents within the mass range explored. Practically, this paper behooves experimental endeavors to consider alternative modes of production that might be prevalent in hidden sector models, as kinetic mixing appears insufficient alone.
Theoretically, this work invites further scrutiny into non-renormalizable interactions inherent to hidden sector communications. Specifically, these interactions could potentially bolster the production of hidden photons under higher reheat temperatures, thereby paving a path for hidden sectors to contribute more substantially to dark matter without overclosure due to kinetic mixing alone.
Conclusion
This paper delivers a meticulous investigation into the viability of hidden photons as lukewarm dark matter candidates, punctuated by rigorous plasma effect analyses and relic abundance computations. While the findings mostly delineate constraints and negative conclusions regarding the dominance of hidden photons in dark matter composition, it implicitly encourages the exploration of other production mechanisms. These avenues hold the potential to address the shortcomings posed by kinetic mixing, thereby enriching the discourse surrounding hidden sectors in particle physics. The intricate interplay between cosmic observations, particle interactions, and theoretical amendments foretells an exciting trajectory for future research in this domain.