Cosmological limitations on the mass of neutral leptons

30 Years of Research in Cosmology, Particle Physics and Astrophysics and How Many More to Discover Dark Matter?

“…This seems to have inspired P. Hut [40] who then set a more general limit on the mass and number of neutral weakly interacting particles the same year. Zeldovich [41] while Peebles in 1982 [42] argued (without specifying a kind of interactions as done by previous authors) that any massive particle with weak interactions could explain the formation of the structures we know if it is heavier than 1 keV. Interestingly enough, a very similar result was obtained from M.I Vysotskii, A.D. Dolgov, I.B.…”

The Effective Hamiltonian for Nonleptonic Decay with Possible m t > m W and the Δ I = 1/2 Rule

“…Finally we note here that, recently a Michigan group' 24 ' recalculated the QCD effects on B°-B mixing for various top masses and concluded that when mt >> mw, the QCD correction T}2 is about 0.2 instead of 0.6 derived earlier' 25 !. The change is dramatic, but in contrary, our results indicate that for OPE coefficients mt > mw would not give rise to too magnificant changes from the old expressions.…”

Massive hidden photons as lukewarm dark matter

“…As a consequence of this freeze out the neutron density is fixed (except for the very slow neutron decay) instead of decreasing exponentially as it would have done if still in thermal equilibrium with protons. Later, nearly all neutrons will convert into 4 He nuclei, which provides an indirect test of this epoch. This is the earliest time in the history of the universe that we can test so far.…”

“…It favors cold dark matter (CDM) that is weakly interacting and non-relativistic at late times. One of the best motivated CDM candidate is a WIMP, a weakly interacting massive particle [3,4]. The ligthest supersymmetric particle is the archetypical WIMP example.…”