Dark Matter Candidates from Particle Physics and Methods of Detection

TL;DR

The paper surveys dark matter candidates linked to key problems in particle physics, arguing that new weak or even superweak interactions naturally arise at the weak scale or via hidden sectors.It analyzes production mechanisms, cosmological implications, and detection prospects across WIMPs, superWIMPs, hidden DM, sterile neutrinos, and axions, highlighting how upcoming experiments can discover or constrain these candidates.A central theme is the synergy between collider physics, cosmology, and astrophysical observations, enabling cross-checks between relic densities and experimental signals to identify the true nature of dark matter.The work underscores that dark matter may not be purely cold and collisionless, and that a variety of signals—from neutrinos and gamma rays to X-ray lines and axion conversions—offer complementary discovery avenues.

Abstract

The identity of dark matter is a question of central importance in both astrophysics and particle physics. In the past, the leading particle candidates were cold and collisionless, and typically predicted missing energy signals at particle colliders. However, recent progress has greatly expanded the list of well-motivated candidates and the possible signatures of dark matter. This review begins with a brief summary of the standard model of particle physics and its outstanding problems. We then discuss several dark matter candidates motivated by these problems, including WIMPs, superWIMPs, light gravitinos, hidden dark matter, sterile neutrinos, and axions. For each of these, we critically examine the particle physics motivations and present their expected production mechanisms, basic properties, and implications for direct and indirect detection, particle colliders, and astrophysical observations. Upcoming experiments will discover or exclude many of these candidates, and progress may open up an era of unprecedented synergy between studies of the largest and smallest observable length scales.

Figures (21)

• Figure 1: The particles of the standard model, represented by circles whose areas are proportional to their masses. The photon and gluon are massless. The Higgs boson has not yet been discovered --- its mass has been taken in the allowed range $114.4~\text{GeV} < m_h < 186~\text{GeV}$ (see text).
• Figure 2: The comoving number density $Y$ (left) and resulting thermal relic density (right) of a 100 GeV, $P$-wave annihilating dark matter particle as a function of temperature $T$ (bottom) and time $t$ (top). The solid contour is for an annihilation cross section that yields the correct relic density, and the shaded regions are for cross sections that differ by 10, $10^2$, and $10^3$ from this value. The dashed contour is the number density of a particle that remains in thermal equilibrium.
• Figure 3: A band of natural values in the $(m_X, \Omega_X/\Omega_{\text{DM}})$ plane for a thermal relic $X$, where $\Omega_{\text{DM}} \simeq 0.23$ is the required total dark matter density discovering.
• Figure 4: Regions of minimal supergravity $(m_0, M_{1/2})$ parameter space for fixed $A_0 = 0$, $\tan\beta = 10$, and $\mu > 0$. The green (yellow) region is cosmologically favored with $0.20 < \Omega_{\chi} < 0.28$ ($0.2 < \Omega_{\chi} < 0.6$). The names of cosmologically-favored regions (focus point, bulk, and co-annihilation) are indicated, along with regions with too much and too little dark matter. The lower right red shaded region is excluded by collider bounds on chargino masses; the upper left red region is excluded by the presence of a stable charged particle. Contours are for neutralino dark matter mass $m_{\chi}$ in GeV. Adapted from Feng:2000zu.
• Figure 5: Regions of minimal UED parameter space with the correct relic density. The light (medium) shaded region has $\Omega_{B^1} h^2 = 0.099 \pm 0.020 \ (0.010)$. The dark shaded region is excluded because the LKP is charged. From Kakizaki:2006dz.