Kvarks

Kvarks are hypothetical elementary fermions proposed in certain speculative extensions of particle physics. They are distinct from the quarks of the Standard Model, though some models keep analogies with quark properties.

Theoretical framework: Kvarks are often assumed to carry a new type of non-abelian charge under a confining gauge group, sometimes called the kvark color force. Like quarks, they would occur in multiplets and form bound states. The specifics—such as the number of flavors, electric charge assignments, and whether they come in left- or right-handed chiral states—vary by model.

Properties: Kvarks are typically posited as spin-1/2 fermions with large masses relative to known quarks. They may be charged under the Standard Model's electroweak interactions to varying degrees, or only via the new force. Some scenarios allow stable or long-lived kvarks, others require rapid decays to Standard Model particles through heavy mediators.

Phenomenology and experimental status: If kvarks exist, they could be produced in high-energy collisions and would form bound states analogous to mesons and baryons of ordinary quarks. Signatures include unusual jet structures, displaced vertices, or missing energy depending on decay channels. To date, kvarks remain hypothetical; no experimental confirmation has been reported, and searches set lower bounds on their masses in specific models.

Relation to quarks and fiction: The term "kvark" is occasionally used in speculative literature as a variant of "quark" or as a separate particle within fictional frameworks. In mainstream physics, the established concept is the quark; kvarks are not part of the confirmed particle zoo.