2 research outputs found
Lightest sterile neutrino abundance within the nuMSM
We determine the abundance of the lightest (dark matter) sterile neutrinos
created in the Early Universe due to active-sterile neutrino transitions from
the thermal plasma. Our starting point is the field-theoretic formula for the
sterile neutrino production rate, derived in our previous work [JHEP
06(2006)053], which allows to systematically incorporate all relevant effects,
and also to analyse various hadronic uncertainties. Our numerical results
differ moderately from previous computations in the literature, and lead to an
absolute upper bound on the mixing angles of the dark matter sterile neutrino.
Comparing this bound with existing astrophysical X-ray constraints, we find
that the Dodelson-Widrow scenario, which proposes sterile neutrinos generated
by active-sterile neutrino transitions to be the sole source of dark matter, is
only possible for sterile neutrino masses lighter than 3.5 keV (6 keV if all
hadronic uncertainties are pushed in one direction and the most stringent X-ray
bounds are relaxed by a factor of two). This upper bound may conflict with a
lower bound from structure formation, but a definitive conclusion necessitates
numerical simulations with the non-equilibrium momentum distribution function
that we derive. If other production mechanisms are also operative, no upper
bound on the sterile neutrino mass can be established.Comment: 34 pages. v2: clarifications and a reference added; published
version. v3: erratum appende
Review of Particle Physics
The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 2,143 new measurements from 709 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as supersymmetric particles, heavy bosons, axions, dark photons, etc. Particle properties and search limits are listed in Summary Tables. We give numerous tables, figures, formulae, and reviews of topics such as Higgs Boson Physics, Supersymmetry, Grand Unified Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology, Particle Detectors, Colliders, Probability and Statistics. Among the 120 reviews are many that are new or heavily revised, including a new review on Machine Learning, and one on Spectroscopy of Light Meson Resonances.
The Review is divided into two volumes. Volume 1 includes the Summary Tables and 97 review articles. Volume 2 consists of the Particle Listings and contains also 23 reviews that address specific aspects of the data presented in the Listings.
The complete Review (both volumes) is published online on the website of the Particle Data Group (pdg.lbl.gov) and in a journal. Volume 1 is available in print as the PDG Book. A Particle Physics Booklet with the Summary Tables and essential tables, figures, and equations from selected review articles is available in print, as a web version optimized for use on phones, and as an Android app