Dark-Matter Decay as a Complementary Probe of Multicomponent Dark Sectors

Abstract

In single-component theories of dark matter, the 2 → 2 amplitudes for dark-matter production, annihilation, and scattering can be related to each other through various crossing symmetries. These crossing relations lie at the heart of the celebrated complementarity which underpins different existing dark-matter search techniques and strategies. In multi-component theories of dark matter, by contrast, there can be many different dark-matter components with differing masses. This then opens up a new, "diagonal" direction for dark-matter complementarity: the possibility of darkmatter decay from heavier to lighter dark-matter components. In this work, we discuss how this new direction may be correlated with the others, and demonstrate that the enhanced complementarity which emerges can be an important ingredient in probing and constraining the parameter spaces of such models.Introduction.-In recent years, many search techniques have been exploited in the hunt for dark matter [1]. These include possible dark-matter production at colliders; direct detection of cosmological dark matter through its scattering off ordinary matter at underground experiments; and indirect detection of dark matter through observation of the remnants of the annihilation of cosmological dark matter into ordinary matter at terrestrial or satellite-based experiments. At first glance, these different techniques may seem to rely on three independent properties of dark matter, namely its amplitudes for production, scattering, and annihilation. However, these three amplitudes are often related to each other through various crossing symmetries. As a result, the different corresponding search techniques are actually correlated with each other through their dependence on a single underlying interaction which couples dark matter to ordinary matter, and the results achieved through any one of these search techniques will have immediate implications for the others as well as for this underlying interaction. This is the origin of the celebrated complementarity which connects the different existing dark-matter search techniques (for a review, see Ref.[2]).

Implications of two-component dark matter induced by forbidden channels and thermal freeze-out

“…(19) and (30), respectively. The cross section is very suppressed by the electron Yukawa coupling (the electron mass).…”

Off-diagonal dark-matter phenomenology: Exploring enhanced complementarity relations in nonminimal dark sectors

“…Off-diagonal dark-matter scenarios exhibit a rich set of complementarity relations [3]. Indeed, as discussed in the Introduction and in Ref.…”

“…In multicomponent dark-matter scenarios, however, the experimental complementarity picture can be even richer and more subtle than it is in traditional, single-component scenarios [3]. One reason is that the multicomponent nature of the dark sector allows for two distinct classes of processes which can generically contribute to the relevant experimental event rates.…”

“…These processes include the inelastic scattering of dark matter with visible matter, dark-matter co-annihilation, and asymmetric pair-production processes at colliders. Moreover, this latter class also includes a wholly different type of process that has no analogue in single-component dark-matter models: the decay of a heavier dark-matter species to a final state comprising a lighter dark-matter species and some number of SM particles [3]. Since the underlying amplitudes associated with dark-matter decay processes are also generally related through crossing symmetries to the amplitudes associated with dark-matter production, scattering, and annihilation, the web of dark-matter complementarity relations in multicomponent dark-matter scenarios is significantly enhanced relative to that which emerges in single-component scenarios.…”

Randomness in the dark sector: Emergent mass spectra and Dynamical Dark Matter ensembles

“…As such, DDM furnishes what may be considered to be the most general example of a non-minimal dark sector, and even reduces to (and thereby incorporates) the simple case of a single hyperstable dark-matter particle as the number of individual states within the DDM ensemble is taken to one. However, as the number of dark-sector states becomes larger, these ensembles give rise to rich collider-based, astrophysical, and cosmological phenomenologies [3][4][5][6][7][8][9] which generalize and even transcend what is possible with a single dark-matter particle alone.…”