355 research outputs found
Probing Minimal Grand Unification through Gravitational Waves, Proton Decay, and Fermion Masses
Motivated by the direct discovery of gravitational waves (GWs) from black
holes and neutron stars, there is a growing interest in investigating GWs from
other sources. Among them, GWs from cosmic strings are particularly fascinating
since they naturally appear in a large class of grand unified theories (GUTs).
Remarkably, a series of pulsar-timing arrays (PTAs) might have already observed
GWs in the nHz regime, hinting towards forming a cosmic string network in the
early universe, which could originate from phase transition associated with the
seesaw scale emerging from GUT. In this work, we show that if these
observations from PTAs are confirmed, GWs from cosmic strings, when combined
with fermion masses, gauge coupling unification, and proton decay constraints,
the parameter space of the minimal SO(10) GUT becomes exceedingly restrictive.
The proposed minimal model is highly predictive and will be fully tested in a
number of upcoming gravitational wave observatories.Comment: 29 pages + references. Comments are welcom
Resurrecting Minimal Yukawa Sector of SUSY SO(10)
Supersymmetric models with Yukawa coupling matrices involving only a
and a of Higgs fields can lead to a predictive and
consistent scenario for fermion masses and mixings, including the neutrino
sector. However, when coupled minimally to a symmetry breaking sector that
includes a and a , these models lead either to an unacceptably
small neutrino mass scale, or to non-perturbative values of the gauge
couplings. Here we show that with the addition of a to the symmetry
breaking sector, the successful predictions of these models for fermion masses
and mixings can be maintained. The enables a reduction of the
symmetry breaking scale to an intermediate value of order GeV,
consistent with the observed neutrino mass spectrum, while preserving
perturbative gauge coupling unification. We obtain an excellent fit to all
fermion masses and mixings in this framework. We analyze carefully the
prediction of the model for CP violation in neutrino oscillations. Consistency
with proton lifetime, however, requires a mini-split SUSY spectrum with the
squarks and sleptons having masses of order 100 TeV, accompanied by TeV scale
gauginos and Higgsinos. Such a spectrum may arise from pure gravity mediation,
which would predict the partial lifetime for the decay to be an order of magnitude above the current experimental
limit.Comment: 29 pages, 3 figures, replacement to match the published versio
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