Feebly interacting particles (FIPs) are subatomic particles defined by having extremely suppressed interactions with the
Standard Model (SM) boson
In particle physics, a boson ( ) is a subatomic particle whose spin quantum number has an integer value (0, 1, 2, ...). Bosons form one of the two fundamental classes of subatomic particle, the other being fermions, which have half odd-intege ...
s and / or
fermion
In particle physics, a fermion is a subatomic particle that follows Fermi–Dirac statistics. Fermions have a half-integer spin (spin 1/2, spin , Spin (physics)#Higher spins, spin , etc.) and obey the Pauli exclusion principle. These particles i ...
s. These particles are potential thermal
dark matter candidates, extending the model of
weakly interacting massive particles
Weakly interacting massive particles (WIMPs) are hypothetical particles that are one of the proposed candidates for dark matter.
There exists no formal definition of a WIMP, but broadly, it is an elementary particle which interacts via gravity an ...
(WIMPs) to include
weakly interacting sub-eV particles (WISPs) and others. FIP physics is also known as ''dark-sector physics''.
[
]
Candidates
FIP candidates could be massive (FIMP / WIMP) or massless and coupled to the
SM particles through some minimal
coupling strength.
[
The light FIPs are theorized to be ]dark matter
In astronomy, dark matter is an invisible and hypothetical form of matter that does not interact with light or other electromagnetic radiation. Dark matter is implied by gravity, gravitational effects that cannot be explained by general relat ...
candidates, and, they provide an explanation for the origin of neutrino masses and CP symmetry in strong interaction
In nuclear physics and particle physics, the strong interaction, also called the strong force or strong nuclear force, is one of the four known fundamental interaction, fundamental interactions. It confines Quark, quarks into proton, protons, n ...
s.[
]
Neutrino
A neutrino ( ; denoted by the Greek letter ) is an elementary particle that interacts via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass is so small ('' -ino'') that i ...
s technically qualify as FIPs, but usually when the acronym "FIP" is used, it is intended to refer to some other, as-yet unknown particle.
Cai, Cacciapaglia, and Lee (2022)[ proposed massive gravitons as feebly Interacting particle candidates.][
]
See also
* WIMP
WiMP is a music streaming service available on mobile devices, tablets, network players and computers. WiMP, standing for "Wireless Music Player," was a music streaming service that emphasized high-quality audio. WiMP offered music and podcast ...
– weakly interacting massive particle
* WISP – weakly interacting sub-eV / slight / slender particle
References
Dark matter
Hypothetical particles
Physics beyond the Standard Model
Astroparticle physics
Exotic matter
{{Particle-stub