Right-Handed Neutrino Dark Matter in the Classically Conformal U(1)′ Extended Standard Model

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dc.contributor.author Okada, Nobuchika
dc.date.accessioned 2019-05-31T16:02:10Z
dc.date.available 2019-05-31T16:02:10Z
dc.date.issued 2017-11-29 en_US
dc.identifier.citation Oda, S., Okada, N., Takahashi, D. (2017): Right-Handed Neutrino Dark Matter in the Classically Conformal U(1)′ Extended Standard Model. Physical Review D, 96(9). DOI: https://doi.org/10.1103/PhysRevD.96.095032 en_US
dc.identifier.uri http://ir.ua.edu/handle/123456789/5666
dc.description.abstract We consider the dark matter (DM) scenario in the context of the classically conformal U(1)′ extended standard model (SM), with three right-handed neutrinos (RHNs) and the U(1)′ Higgs field. The model is free from all of the U(1)′ gauge and gravitational anomalies in the presence of the three RHNs. We introduce a Z_2 parity in the model, under which an odd parity is assigned to one RHN, while all of the other particles are assigned to be Z_2 even, and hence the Z_2-odd RHN serves as a DM candidate. In this model, the U(1)′ gauge symmetry is radiatively broken through the Coleman-Weinberg mechanism, by which the electroweak symmetry breaking is triggered. There are three free parameters in our model—the U(1)′ charge of the SM Higgs doublet (x_H), the new U(1)′ gauge coupling (g_X), and the U(1)′ gauge boson (Z′) mass (m_Z′)—which are severely constrained in order to solve the electroweak vacuum instability problem, and satisfy the LHC Run-2 bounds from the search for the Z′ boson resonance. In addition to these constraints, we investigate the RHN DM physics. Because of the nature of classical conformality, we find that a RHN DM pair mainly annihilates into the SM particles through Z′ boson exchange. This is the so-called Z′-portal DM scenario. Combining the electroweak vacuum stability condition, the LHC Run-2 bounds, and the cosmological constraint from the observed DM relic density, we find that all constraints work together to narrow the allowed parameter regions and, in particular, exclude m_Z′ ≲ 3.5 TeV. For the obtained allowed regions, we calculate the spin-independent cross section of the RHN DM with nucleons. We find that the resultant cross section is well below the current experimental upper bounds. en_US
dc.format.mimetype application/pdf en_US
dc.language English en_US
dc.title Right-Handed Neutrino Dark Matter in the Classically Conformal U(1)′ Extended Standard Model en_US
dc.type text en_US


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