Abstract
The mirror twin Higgs framework allows for a natural Higgs mass while being consistent with collider bounds on colored symmetry partners to standard model quarks. This mechanism relies crucially on a discrete symmetry which relates each standard model field to a mirror partner. These partners are charged under gauge groups identical to, but distinct from, those in the standard model. The minimal twin Higgs scenario provides only one low-energy connection between the visible and twin sectors, the light Higgs boson. We present a new class of portals connecting the two sectors, using fields that have no twin partner under the discrete symmetry. Scalar, fermion, and vector states may provide such singleton portals, each with unique features and experimental signatures. The vector portal, in particular, provides a variety of renormalizable interactions relevant for the LHC. We provide concrete constructions of these portals and determine their phenomenology and opportunities to probe the twin sector at the LHC. We also sketch a scenario in which the structure of the twin sector itself can be tested.
Highlights
The hierarchy between the electroweak scale, which sets the Higgs mass, and the Planck scale is arguably a strong link between Higgs and BSM physics
The mirror twin Higgs framework allows for a natural Higgs mass while being consistent with collider bounds on colored symmetry partners to standard model quarks
We present a new class of portals connecting the two sectors, using fields that have no twin partner under the discrete symmetry
Summary
The simplest type of singleton portal is a scalar, φ. Acquires a vacuum expectation value (VEV), the first term in eq (2.1) spontaneously breaks the Z2 symmetry.1 This provides an attractive origin of the soft Z2 breaking required by Higgs coupling measurements [27]. This includes a simple φ → −φ symmetry that might stabilize φ against decay, making it a possible dark matter candidate.2 This |φ|2 interaction is SU(4) symmetric in the Higgs fields, and does not contribute to the potential of pseudo-Nambu-Goldstone bosons (pNGBs) like the physical Higgs. Having equal VEVs in each sector implies the Higgs’ couplings to visible fields are half the SM prediction, which is ruled out by LHC measurements This result is modified by introducing a Z2-odd singleton, φ = vφ + φ,. While the neutral singleton provides a simple origin of the soft Z2 breaking in the Higgs potential, its experimental signatures may be too faint to see in the near future
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