Abstract
Electromagnetically neutral dark sector particles may directly couple to the photon through higher dimensional effective operators. Considering electric and magnetic dipole moment, anapole moment, and charge radius interactions, we derive constraints from stellar energy loss in the Sun, horizontal branch and red giant stars, as well as from cooling of the proto-neutron star of SN1987A. We provide the exact formula for in-medium photon-mediated pair production to leading order in the dark coupling, and compute the energy loss rates explicitly for the most important processes, including a careful discussion on resonances and potential double counting between the processes. Stringent limits for dark states with masses below $3\,$keV ($40\,$MeV) arise from red giant stars (SN1987A), implying an effective lower mass-scale of approximately $10^9\,$GeV ($10^7\,$GeV) for mass-dimension five, and $100\,$GeV ($2.5\,$TeV) for mass-dimension six operators as long as dark states stream freely; for the proto-neutron star, the trapping of dark states is also evaluated. Together with direct limits previously derived by us in Chu et al. (2018), this provides the first comprehensive overview of the viability of effective electromagnetic dark-state interactions below the GeV mass-scale.
Highlights
The prospect that new physics might be hiding under our noses in the form of light dark states that have been in kinematic reach for decades is most intriguing if not seemingly preposterous
This is achieved by setting ΠT;L in the corresponding propagator to zero. Since this should overestimate the production rate at sχχ ≤ ΠT;L, we have tested an opposite option of choosing ΠT;L → −ΠT;LðEχ þEχ Þ to avoid the singularity, which underestimates the production rate. We find that both prescriptions lead to same results at the percent level, which justifies our simplification of taking ΠT;L ≡ 0 for the photon that directly couples to χ
We show the line which corresponds to the thermal freeze-out scenario which generates the observed dark matter abundance, such scenario has been excluded by various constraints for this model; see our previous work [30]
Summary
The prospect that new physics might be hiding under our noses in the form of light dark states that have been in kinematic reach for decades is most intriguing if not seemingly preposterous. The direct test of such physics, i.e., new particles and interactions below the GeV-scale has become a major field in recent years [1,2] and provides a complementary direction to the beyond-SM searches at the energy frontier. Astrophysical constraints on long-lived dark states that are derived from stellar cooling arguments [3] are typically so severe that the cases for laboratory. If the mass of V, mV, originates from a Higgs mechanism, implying an additional scalar particle in the vicinity of mV, stellar cooling constraints obliterate any prospects of probing such a model below the keV-region, as limits on millicharged particles apply. If χ is long-lived, additional constraints from cosmology, astrophysics, and direct DM searches apply, and in [30] we have considered the most important ones that are crucial in the MeV-GeV mass bracket of χ. Several Appendixes provide details on the calculations and are referenced in the main text
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
