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New constraints on neutrino physics from BOOMERANG data
1NORDITA, Blegdamsvej 17, DK-2100 Copenhagen, Denmark.
Physical Review Letters
|November 4, 2000
Summary
Cosmic microwave background data from the BOOMERANG experiment provide a strong upper limit on radiation density. This analysis sets a 2-sigma bound of N(nu)<=13 for neutrino species, impacting theories on decaying neutrinos and lepton asymmetry.
Area of Science:
- Cosmology
- Particle Physics
Background:
- The cosmic microwave background (CMB) radiation provides crucial information about the early Universe.
- The BOOMERANG experiment has collected precise data on CMB anisotropy.
Purpose of the Study:
- To analyze BOOMERANG data to constrain cosmological parameters.
- To establish an upper bound on radiation density at recombination.
Main Methods:
- Likelihood analysis of BOOMERANG CMB anisotropy data.
- Interpretation of results in terms of neutrino species and lepton asymmetry.
Main Results:
- A 2-sigma upper bound of N(nu)<=13 equivalent neutrino species.
- The bound is flavor-insensitive and applies to later epochs.
- Severe limits are placed on scenarios involving decaying neutrinos.
Conclusions:
- The derived bound provides a firm upper limit on lepton asymmetry in the Universe.
- The findings challenge certain cosmological models with decaying neutrinos.