WISP (quantum mechanics)

In quantum mechanics, the acronym WISP refers to a largely hypothetical Weakly Interacting Sub-eV Particle, or Weakly Interacting Slender Particle or Weakly Interacting Slim Particle– low-mass particles which rarely interact with conventional particles (if ever). With the exception of “active” neutrinos, all WISPs are hypothetical particles.
The term is essentially synonymous with “"Axion-like particle"” (ALP).
Sources.
The various sources of WISPs includes, the hot astrophysical plasma and the transport energies of stars.
Discussion.
Although left-chiral neutrinos and right-chiral antineutrinos – “active” neutrinos – are known to exist, and technically do satisfy the description of the term, “"WISP"” is most often used to refer to a low-mass hypothetical particle which is a dark matter candidate. Examples include:
All WISPs are dark matter candidates, except for active neutrinos, whose cumulative density could not be sufficient to account for the observed effects of dark matter, based on current estimates of their numbers and mass.
Massive counterpart.
WISPs are the low-mass counterpart of WIMPs: Weakly Interacting Massive Particles.