Gravitational wave signatures from discrete flavor symmetries. (arXiv:2009.01903v3 [hep-ph] UPDATED)
<a href="http://arxiv.org/find/hep-ph/1/au:+Gelmini_G/0/1/0/all/0/1">Graciela B. Gelmini</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Pascoli_S/0/1/0/all/0/1">Silvia Pascoli</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Vitagliano_E/0/1/0/all/0/1">Edoardo Vitagliano</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Zhou_Y/0/1/0/all/0/1">Ye-Ling Zhou</a>
Non-Abelian discrete symmetries have been widely used to explain the patterns
of lepton masses and flavor mixing. In these models, a given symmetry is
assumed at a high scale and then is spontaneously broken by scalars (the
flavons), which acquire vacuum expectation values. Typically, the resulting
leading order predictions for the oscillation parameters require corrections in
order to comply with neutrino oscillation data. We introduce such corrections
through an explicit small breaking of the symmetry.
This has the advantage of solving the cosmological problems of these models
without resorting to inflation. The explicit breaking induces an energy
difference or “bias” between different vacua and drives the evolution of the
domain walls, unavoidably produced after the symmetry breaking, towards their
annihilation. Importantly, the wall annihilation leads to gravitational waves
which may be observed in current and/or future experiments. We show that a
distinctive pattern of gravitational waves with multiple overlapped peaks is
generated when walls annihilate, which is within the reach of future detectors.
We also show that cosmic walls from discrete flavor symmetries can be
cosmologically safe for any spontaneous breaking scale between 1 and $10^{18}$
GeV, if the bias is chosen adequately, without the need to inflate the walls
away. We use as an example a particular $A_4$ model in which an explicit
breaking is included in right-handed neutrino mass terms.
Non-Abelian discrete symmetries have been widely used to explain the patterns
of lepton masses and flavor mixing. In these models, a given symmetry is
assumed at a high scale and then is spontaneously broken by scalars (the
flavons), which acquire vacuum expectation values. Typically, the resulting
leading order predictions for the oscillation parameters require corrections in
order to comply with neutrino oscillation data. We introduce such corrections
through an explicit small breaking of the symmetry.
This has the advantage of solving the cosmological problems of these models
without resorting to inflation. The explicit breaking induces an energy
difference or “bias” between different vacua and drives the evolution of the
domain walls, unavoidably produced after the symmetry breaking, towards their
annihilation. Importantly, the wall annihilation leads to gravitational waves
which may be observed in current and/or future experiments. We show that a
distinctive pattern of gravitational waves with multiple overlapped peaks is
generated when walls annihilate, which is within the reach of future detectors.
We also show that cosmic walls from discrete flavor symmetries can be
cosmologically safe for any spontaneous breaking scale between 1 and $10^{18}$
GeV, if the bias is chosen adequately, without the need to inflate the walls
away. We use as an example a particular $A_4$ model in which an explicit
breaking is included in right-handed neutrino mass terms.
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