Observable Gravitational Waves From Higgs Inflation in SUGRA
  We consider models of chaotic inflation driven by the real parts of a
conjugate pair of Higgs superfields involved in the spontaneous breaking of a
grand unification symmetry at a scale assuming its supersymmetric value.
Employing quadratic Kaehler potentials with a prominent shift-symmetric part
proportional to c- and a tiny violation, proportional to c+, included in a
logarithm we show that the inflationary observables provide an excellent match
to the recent Planck and Bicep2/Keck Array results setting, e.g.,
0.012<=c+/c-<1/N where -N<0 is the prefactor of the logarithm. Moreover, we
analyze several possible stabilization mechanisms for the non-inflaton
accompanying superfield using just quadratic terms. In all cases, inflation can
be attained for subplanckian inflaton values with the corresponding effective
theories retaining the perturbative unitarity up to the Planck scale.
