Cosmological bounds on tachyonic neutrinos

TL;DR

Cosmological observations strongly constrain superluminal neutrino models, ruling out Lorentz-invariant tachyonic explanations for OPERA experiment anomalies and indicating any superluminal neutrinos would imply Lorentz symmetry violation.

Contribution

The paper demonstrates that cosmological bounds exclude Lorentz-invariant tachyonic neutrinos as an explanation for superluminal neutrino observations.

Findings

Cosmological bounds impose $v-1<7.1\times 10^{-23}$ from CMB data.

Nucleosynthesis constraints limit $v-1<0.86\times 10^{-12}$ at OPERA energies.

Superluminal neutrinos at accelerator scales would require Lorentz symmetry violation.

Abstract

Recent time-of-flight measurements on muon neutrinos in the OPERA neutrino oscillation experiment have found anomalously short times compared to the light travel-times, corresponding to a superluminal velocity, $v-1=2.37\pm0.32\times 10^{-5}$ in units where $c=1$. We show that cosmological bounds rule out an explanation involving a Lorentz invariant tachyonic neutrino. At the OPERA energy scale, nucleosynthesis constraints imply $v-1<0.86\times 10^{-12}$ and the Cosmic Microwave Background observations imply $v-1<7.1\times 10^{-23}$. The CMB limit on the velocity of a tachyon with an energy of 10 MeV is stronger than the SN1987A limit. Superluminal neutrinos that could be observed at particle accelerator energy scales would have to be associated with Lorentz symmetry violation.