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A Viable New Model for Dark Matter

X. G. Wang, A. W. Thomas

Abstract

We present a new model of the dark sector involving Dirac fermion dark matter, with axial coupling to a dark photon which provides a portal to Standard Model particles. In the non-relativistic limit, this implies that the dominant effective operator relevant to direct detection is ${\cal O}_8$. The resulting event rate for direct detection is suppressed by either the dark matter velocity or the momentum transfer. In this scenario there are much wider regions of the dark parameter space that are consistent with all of the existing constraints associated with thermal relic density, direct detection and collider searches.

A Viable New Model for Dark Matter

Abstract

We present a new model of the dark sector involving Dirac fermion dark matter, with axial coupling to a dark photon which provides a portal to Standard Model particles. In the non-relativistic limit, this implies that the dominant effective operator relevant to direct detection is . The resulting event rate for direct detection is suppressed by either the dark matter velocity or the momentum transfer. In this scenario there are much wider regions of the dark parameter space that are consistent with all of the existing constraints associated with thermal relic density, direct detection and collider searches.

Paper Structure

This paper contains 2 sections, 33 equations, 3 figures.

Table of Contents

  1. Cancellation in the evaluation of ${\cal O}_4$
  2. Contributions of ${\cal O}_8$ and ${\cal O}_9$

Figures (3)

  • Figure 1: (Left panels): The lower limits on $y$ from the thermal relic density. The EWPO constraints are derived by converting the exclusion limits on $\epsilon$ from Ref. Curtin:2014ccaLoizos:2023xbj, with $M_{A_D}$ being extended up to 3 TeV. The shaded areas are the eigen-mass repulsion regions Kribs:2020vyk corresponding to different values of $\alpha_D$, in which the dark photon parameters are not accessible. (Right panels): the corresponding constraints on the dimensionless coupling of ${\cal O}_8$. The Xenon100 limits XENON:2017fdd have been relaxed by a factor of $A^2/Z^2$. The upper bounds from LZ are derived according to the rescaling in Eq. (\ref{['eq:LZ']}).
  • Figure 2: The lower bounds on $\epsilon$ from the thermal relic density (dashed line), which are compared with the modified upper limits (solid lines) from the CMS collaboration CMS:2019buh, according to Eq. (\ref{['eq:relaxed-CMS']}).
  • Figure 3: The velocity and time averaged scattering rate, $\langle \overline{ \frac{d\sigma_{\chi T}}{d E_R} } \rangle$, up to a factor of $\frac{2 m_T}{4\pi} (c^p_8)^2$. Note that the green (dotted) line shows the absolute value of the interference term, as $F^{(p,p)}_{\Sigma',\Delta}$ becomes negative when $E_R > 30$ keV.