Journal
PHYSICS LETTERS B
Volume 718, Issue 4-5, Pages 1162-1165Publisher
ELSEVIER
DOI: 10.1016/j.physletb.2012.12.019
Keywords
-
Funding
- INFN
- U.S. National Science Foundation (NSF) [PHY-1053663]
- NSF [PHY-0757959]
- Department of Energy (DOE) [DE-FG02-91ER40690]
- Division Of Physics
- Direct For Mathematical & Physical Scien [1053663] Funding Source: National Science Foundation
Ask authors/readers for more resources
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 study to account for the dark radiation by means of the right-handed partners of the three, left-handed, standard model neutrinos. We show that milli-weak interactions of these Dirac states (through their coupling to a TeV-scale Z' gauge boson) may allow the v(R)'s to decouple much earlier, at a higher temperature, than their left-handed counterparts. If the v(R)'s decouple during the quark-hadron crossover transition, they are considerably cooler than the v(L)'s and contribute less than 3 extra equivalent neutrinos to the early Universe energy density. For decoupling in this transition region, the 3v(R) generate Delta N-v = 3(T-vR/T-vL)(4) < 3, extra relativistic degrees of freedom at BBN and at the CMB epochs. Consistency with present constraints on dark radiation permits us to identify the allowed region in the parameter space of Z' masses and couplings. Remarkably, the allowed region is within the range of discovery of LHC14. (C) 2012 Elsevier B.V. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available