1110.2015 (R. A. Konoplya et al.)

Stability of tardyons and tachyons in the rotating and expanding
Universe    [PDF]

R. A. Konoplya, A. Zhidenko

In the present paper we analyze the spectrum of quasinormal modes for massive
scalar and Dirac fields, allowing for both tardyonic ($\mu^2 >0$) and tachyonic
($\mu^2 <0$) masses, in the expanding and rotating cosmological background. The
found spectrum shows a number of peculiar features, which are absent in the
Minkowski space-time. A hypothetical particle which moves faster than the
light, a tachyon, is known to be classically unstable in the Minkowski
space-time. This instability has its analog at the quantum level: small vacuum
fluctuations of the field lead to the unbounded growth of the amplitude, so
that appearance of the real tachyons in the spectrum means the catastrophic
instability for the theory. It has been conjectured a long time ago that
possibly the lightest particles with a nonzero mass, the neutrino, may be a
tachyon. Here we shall show that in the rotating and expanding Universe
tachyons are stable if their mass is less than some constant, which is related
to the Universe's rotation and expansion scales. Current upper bound on the
rotation scale gives us a very small upper bound on tachyon's mass which is
many orders less than the mass of electron. This might be an explanation why
only very light particles have a chance to be tachyons. It is shown that the
spectrum of the "normal" ($\mu^2 >0$) Dirac field has a discontinuity as a
function of the z-component of the wave vector $k_z$ at $k_z = 0$. Keywords:
OPERA, superluminal neutrino.

View original: http://arxiv.org/abs/1110.2015