Increasing Neff with particles in thermal equilibrium with neutrinos
By Céline Boehm, M. Dolan, C. McCabe. 2012
136 citations recorded by the source corpus.
Recent work on increasing the effective number of neutrino species (Neff) in the early universe has focussed on introducing extra relativistic species ('dark radiation'). We draw attention to another possibility: a new particle of mass 10 MeV that remains in thermal equilibrium with neutrinos until it becomes non-relativistic increases the neutrino temperature relative to the photons. We demonstrate that this leads to a value of Neff that is greater than three and that Neff at CMB formation is larger than at BBN. We investigate the constraints on such particles from the primordial abundance of helium and deuterium created during BBN and from the CMB power spectrum measured by ACT and SPT and find that they are presently relatively unconstrained. We forecast the sensitivity of the Planck satellite to this scenario: in addition to dramatically improving constraints on the particle mass, in some regions of parameter space it can discriminate between the new particle being a real or complex scalar.
Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/e6a0078b927f6d372ba4df85952cb261e1818da9
How researchers see this paper
The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.
In Astronomy and Astrophysics
In Nuclear and High Energy Physics
Citations in the corpus
- Refined bounds on MeV-scale thermal dark sectors from BBN and the CMB (2019, methodology): “Regarding BBN constraints, we can differentiate between two types of studies: some that fixed the baryon-to-photon ratio to be the best-fit from CMB observations at the time [95, 96, 99, 102], while others allowed Ωbh 2 to vary and then fitted it to measurements of YP and D/H|P simultaneously with m”
- Reducing the H0 and σ8 tensions with dark matter-neutrino interactions. (2017, background): “neutrino fluid and mimic an increase in the value of Neff [46,47].”
- Dark, cold, and noisy: constraining secluded hidden sectors with gravitational waves (2018, unknown): “afterwards [30].”
- The Phenomenology of Right Handed Neutrinos (2013, background): “046 even if there are only three neutrinos [234–236].”
- New light species and the CMB (2013, background): “This heavy species can alter the neutrino distribution through annihilation or decay [115].”
- Extended gamma-ray emission from Coy Dark Matter (2014, background): “Other examples of CDM include light neutralino dark matter, which can lead to a large signal in the effective number of neutrinos Neff but nowhere else [18, 19].”
- Neutrino decoupling beyond the Standard Model: CMB constraints on the Dark Matter mass with a fast and precise Neff evaluation (2018, background): “The agreement between the observations of the Cosmic Microwave Background (CMB) [1, 2], and the primordial element abundances [3, 4] with the SM prediction [5–15] of three relativistic neutrino species represents a success of the Standard Model, and constitues a non-trivial test for some of its exte”
- Phases of new physics in the CMB (2015, background): “[22–30]) or from non-standard properties of the SM neutrinos (e.”