Non-Decoupling New Particles

Abstract

We initiate the study of a new class of beyond the Standard Model states that we call "Loryons." They have the defining characteristic of being non-decoupling, in the sense that their physical mass is dominated by a contribution from the vacuum expectation value of the Higgs boson. The stakes are high: the discovery of a Loryon would tell us that electroweak symmetry must be non-linearly realized in the effective field theory of the Standard Model. Loryons have their masses bounded from above by perturbative unitarity considerations and thus define a finite parameter space for exploration. After providing a complete catalog of Loryon representations under mild assumptions, we turn to examining the constraints on the parameter space from Higgs couplings measurements, precision electroweak tests, and direct collider searches. We show that most fermionic candidates are already ruled out (with some notable exceptions), while much of the scalar Loryon parameter space is still wide open for discovery.

55 pages, 11 figures, 13 tables

References in corpus (9)

• Gauge Singlet Scalars as Cold Dark Matter
• Search for long-lived charged particles in proton-proton collisions at sqrt(s) = 13 TeV
• Search for heavy charged long-lived particles in the ATLAS detector in 36.1 fb${}^{-1}$ of proton-proton collision data at $\sqrt{s}=13$ TeV
• Is SMEFT Enough?
• Search for pair-produced resonances decaying to jet pairs in proton-proton collisions at sqrt(s) = 8 TeV
• Searching for Lepton Flavour (Universality) Violation and Collider Signals from a Singly-Charged Scalar Singlet
• Search for doubly and singly charged Higgs bosons decaying into vector bosons in multi-lepton final states with the ATLAS detector using proton-proton collisions at $\sqrt{s}$ = 13 TeV
• Unitarity Violation and the Geometry of Higgs EFTs
• The Anomalous Case of Axion EFTs and Massive Chiral Gauge Fields

Cited by in corpus (10)

• Hilbert Series, the Higgs Mechanism, and HEFT
• Complete NLO Operators in the Higgs Effective Field Theory
• An EFT hunter's guide to two-to-two scattering: HEFT and SMEFT on-shell amplitudes
• A new Higgs effective field theory and the new no-lose theorem
• Unitarity Bounds on Effective Field Theories at the LHC
• Primary Observables for Indirect Searches at Colliders
• A Strongly First-Order Electroweak Phase Transition from Loryons
• Relic Challenges for Vector-Like Fermions as Connectors to a Dark Sector
• Contributions to the Muon $g-2$ from a Three-Form Field
• Beyond SMEFT with $b\to c{\tau }^{-}\bar{\nu }$