Dark matter produced from right-handed neutrinos

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Right-handed neutrinos (v R ) offer an intriguing portal to new physics in hidden sectors where dark matter (DM) may reside. In this work, we delve into the simplest hidden sector involving only a real scalar exclusively coupled to v R , referred to as the v R -philic scalar. We investigate the viability of the v R -philic scalar to serve as a DM candidate, under the constraint that the coupling of v R to the standard model is determined by the seesaw relation and is responsible for the observed DM abundance. By analyzing the DM decay channels and solving Boltzmann equations, we identify the viable parameter space. In particular, our study reveals a lower bound (2.6 × 105 GeV) on the mass of v R for the v R -philic scalar to be DM. The DM mass may vary from sub-MeV to sub-GeV. Within the viable parameter space, monochromatic neutrino lines from DM decay can be an important signal for DM indirect detection.

Section: Production Via 2n → 2ϕmentioning

confidence: 99%

“…If y is sufficiently small, one can use the freeze-in formula to evaluate the number density of ϕ produced via this process [30]:…”

Section: Production Via 2n → 2ϕmentioning

confidence: 99%

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The v _R-philic scalar dark matter

Xu,

Zhou,

Zhu

2024

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“…• First, the RH neutrinos can readily be thermalized in the SM plasma via two-body/ inverse decay or rapid active-neutrino oscillations [32,33]. Before the electroweak gauge symmetry breaking, the majoron couples to RH neutrinos via…”

Section: Majoron Cosmology In the Low-scale Seesaw Scenariomentioning

confidence: 99%

A cosmological sandwiched window for lepton-number breaking scale

Li,

2024

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A singlet majoron can arise from the seesaw framework as a pseudo-Goldstone boson when the heavy Majorana neutrinos acquire masses via the spontaneous breaking of global U(1) L symmetry. The resulting cosmological impacts are usually derived from the effective majoron-neutrino interaction, and the majoron abundance is accumulated through the freeze-in neutrino coalescence. However, a primordial majoron abundance can be predicted in a minimal setup and lead to distinctive cosmological effects. In this work, we consider such a primordial majoron abundance from relativistic freeze-out and calculate the modification to the effective neutrino number N eff. We demonstrate that the measurements of N eff will constrain the parameter space from a primordial majoron abundance in an opposite direction to that from neutrino coalescence. When the contributions from both the primordial abundance and the freeze-in production coexist, the U(1) L -breaking scale (seesaw scale) f will be pushed into a “sandwiched window”. Remarkably, for majoron masses below 1 MeV and above the eV scale, the future CMB-S4 experiment will completely close such a low-scale seesaw window for f ∈ [1,105] GeV. We highlight that any new light particle with a primordial abundance that couples to Standard Model particles may lead to a similar sandwiched window, and such a general phenomenon deserves careful investigation.

“…Therefore, it is plausible to consider that DM may reside in a hidden dark sector that barely interacts with quarks or charged leptons. For instance, the dark sector could be connected to the SM only via the neutrino portal [1][2][3][4][5][6][7][8][9][10][11], suggesting a scenario where DM predominantly interacts with neutrinos rather than other SM particles. This scenario, despite being generically difficult to probe in direct or indirect detection experiments, may still leave discernible cosmological imprints.…”

Section: Introductionmentioning

confidence: 99%

Imprints of light dark matter on the evolution of cosmic neutrinos

Wang,

2024

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Neutrinos are often considered as a portal to new physics beyond the Standard Model (SM) and might possess phenomenologically interesting interactions with dark matter (DM). This paper examines the cosmological imprints of DM that interacts with and is produced from SM neutrinos at temperatures below the MeV scale. We take a model-independent approach to compute the evolution of DM in this framework and present analytic results which agree well with numerical ones. Both freeze-in and freeze-out regimes are included in our analysis. Furthermore, we demonstrate that the thermal evolution of neutrinos might be substantially affected by their interaction with DM. We highlight two distinctive imprints of such DM on neutrinos: (i) a large, negative contribution to N eff, which is close to the current experimental limits and will readily be probed by future experiments; (ii) spectral distortion of the cosmic neutrino background (CνB) due to DM annihilating into neutrinos, a potentially important effect for the ongoing experimental efforts to detect CνB.