Zobrazeno 1 - 10
of 203
pro vyhledávání: '"Steigman, Gary"'
Autor:
Steigman, Gary, Scherrer, Robert J.
The asymmetry between matter and antimatter is key to the existence and nature of our Universe. A measure of the matter - antimatter asymmetry of the Universe is provided by the present value of the universal ratio of baryons (baryons minus antibaryo
Externí odkaz:
http://arxiv.org/abs/1801.10059
Autor:
Steigman, Gary
A thermal relic, often referred to as a weakly interacting massive particle (WIMP), is a particle produced during the early evolution of the Universe whose present (relic) abundance depends only on its mass and its thermally averaged annihilation cro
Externí odkaz:
http://arxiv.org/abs/1502.01884
Autor:
Nollett, Kenneth M., Steigman, Gary
Publikováno v:
Phys. Rev. D 91, 083505 (2015)
(abridged) In the presence of a light WIMP (mass m_chi < 30 MeV), there are degeneracies among the WIMP's nature, its couplings to standard model particles, its mass, and the number of equivalent (additional) neutrinos, Delta N_nu. These degeneracies
Externí odkaz:
http://arxiv.org/abs/1411.6005
Autor:
Steigman, Gary, Nollett, Kenneth M.
Very light WIMPs (chi), thermal relics that annihilate late in the early Universe, change the energy and entropy densities at BBN and at recombination. BBN, in combination with the CMB, can remove some of the degeneracies among light WIMPs and equiva
Externí odkaz:
http://arxiv.org/abs/1402.5399
Autor:
Steigman, Gary, Nollett, Kenneth M.
Recent updates to the observational determinations of the primordial abundances of helium and deuterium are compared to the predictions of BBN to infer the universal ratio of baryons to photons (or, the present Universe baryon mass density parameter
Externí odkaz:
http://arxiv.org/abs/1401.5488
Autor:
Nollett, Kenneth M., Steigman, Gary
Publikováno v:
Phys. Rev. D 89, 083508 (2014)
(Abridged) In the presence of a light WIMP (< 30 MeV), there are degeneracies among the nature of the WIMP, its couplings to standard model particles, its mass m_chi, and the number of equivalent neutrinos beyond the standard model, Delta N_nu. These
Externí odkaz:
http://arxiv.org/abs/1312.5725
Autor:
Steigman, Gary
Publikováno v:
Phys. Rev. D 87 (2013) 103517
According to conventional wisdom, in the standard model (SM) of particle physics and cosmology the effective number of neutrinos is Neff=3 (more precisely, 3.046). In extensions of the standard model allowing for the presence of DeltaNnu equivalent n
Externí odkaz:
http://arxiv.org/abs/1303.0049
Precision data from cosmology (probing the CMB decoupling epoch) and light-element abundances (probing the BBN epoch) have hinted at the presence of extra relativistic degrees of freedom, the so-called "dark radiation." We present a model independent
Externí odkaz:
http://arxiv.org/abs/1211.0186
Autor:
Steigman, Gary
Publikováno v:
Advances in High Energy Physics, 2012 (2012) 268321
According to the standard models of particle physics and cosmology, there should be a background of cosmic neutrinos in the present Universe, similar to the cosmic microwave photon background. The weakness of the weak interactions renders this neutri
Externí odkaz:
http://arxiv.org/abs/1208.0032
Publikováno v:
Phys.Rev. D86 (2012) 023506
If dark matter (DM) is a weakly interacting massive particle (WIMP) that is a thermal relic of the early Universe, then its total self-annihilation cross section is revealed by its present-day mass density. The canonical thermally averaged cross sect
Externí odkaz:
http://arxiv.org/abs/1204.3622