Abstract
We propose a new nonthermal mechanism of dark matter production based on vacuum misalignment. A global X-charge asymmetry is generated at high temperatures, under which both the will-be Higgs boson and the dark matter are charged. At lower energies, the vacuum changes alignment and breaks the U(1)_{X}, leading to the emergence of the Higgs bosonand of a fraction of charge asymmetry stored in the stable dark matter relic. This mechanism can be present in a wide variety of models based on vacuum misalignment, and we demonstrate it in a composite Higgs template model, where all the necessary ingredients are naturally present. A light pseudo-scalar η is always predicted, with interesting implications for cosmology, future supernova observations and exotic Z→γη decays.
Highlights
Institut de Physique des 2 Infinis (IP2I), CNRS/IN2P3, UMR5822, 69622 Villeurbanne, France and Universitede Lyon, Universite Claude Bernard Lyon 1, 69001 Lyon, France
We propose a new nonthermal mechanism of dark matter production based on vacuum misalignment
This mechanism can be present in a wide variety of models based on vacuum misalignment, and we demonstrate it in a composite Higgs template model, where all the necessary ingredients are naturally present
Summary
Institut de Physique des 2 Infinis (IP2I), CNRS/IN2P3, UMR5822, 69622 Villeurbanne, France and Universitede Lyon, Universite Claude Bernard Lyon 1, 69001 Lyon, France. In this Letter we propose a new mechanism for nonthermal DM production based on vacuum misalignment, in models where the Higgs boson arises as a pseudo-Goldstone boson from a spontaneously broken global symmetry. The mechanism we propose requires the following key ingredients: (i) an exact Z2 symmetry that keeps a DM candidate stable; (ii) right below the global symmetry breaking phase transition at THL, the vacuum of the theory is an essentially Higgsless (HL) phase (we refer to this as a Higgsless phase even though a state with the quantum numbers of the isosinglet Higgs boson is present because this state is expected very heavy at the transition), where the electroweak symmetry is broken at a scale f ≫ vSM 1⁄4 246 GeV, and a global Uð1ÞX symmetry remains unbroken; (iii) at THL, an asymmetry is generated in—or transferred to—the Uð1ÞX charged states, some of which are odd under Z2; (iv) at TÃ < THL, the vacuum starts rotating away from the TC vacuum, and Uð1ÞX is spontaneously broken; (v) at T ≈ 0, the theory settles on the standard pseudo-Goldstone Higgs vacuum, where the misalignment reproduces the electroweak (EW) scale vSM
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