Shift symmetry and Higgs inflation in supergravity with observable gravitational waves

Abstract

Abstract:We demonstrate how to realize within supergravity a novel chaotic-type inflationary scenario driven by the radial parts of a conjugate pair of Higgs superfields causing the spontaneous breaking of a grand unified gauge symmetry at a scale assuming the value of the supersymmetric grand unification scale. The superpotential is uniquely determined at the renormalizable level by the gauge symmetry and a continuous R symmetry. We select two types of Kähler potentials, which respect these symmetries as well as an approximate shift symmetry. In particular, they include in a logarithm a dominant shift-symmetric term proportional to a parameter c − together with a small term violating this symmetry and characterized by a parameter c + . In both cases, imposing a lower bound on c − , inflation can be attained with subplanckian values of the original inflaton, while the corresponding effective theory respects perturbative unitarity for r ± = c + /c − ≤ 1. These inflationary models do not lead to overproduction of cosmic defects, are largely independent of the one-loop radiative corrections and accommodate, for natural values of r ± , observable gravitational waves consistently with all the current observational data. The inflaton mass is mostly confined in the range (3.7 − 8.1) × 10 10 GeV.

Starobinsky Inflation: From Non-SUSY to SUGRA Realizations

“…, 7, 9 and 10, as shown in Table 1. For = 1, our result reproduces those of similar models [31,[47][48][49][50][51][52][68][69][70]. The stability problem can be cured if we include in 3 a higher order term of the form | | 4 with ∼ 1, or assuming that 2 = 0 [75].…”

“…Indeed, when parameterizes the (2, 1)/( (2) × (1)) Kähler manifold [20,21], the inflationary trajectory turns out to be unstable with respect to the fluctuations of . This difficulty can be overcome by adding a sufficiently large term | | 4 , with > 0 and | | ∼ 1, in the logarithmic function appearing in , as suggested in [64] for models of nonminimal (chaotic) inflation [47][48][49] and applied in [50][51][52][53][54][65][66][67][68][69][70]. This solution, however, deforms slightly the Kähler manifold [71].…”

Kinetically modified non-minimal inflation with exponential frame function

“…Refs. [13,14,23]. Under these circumstances, our results can be reproduced by using exclusively V CI in Eq.…”

“…(1.1) and (1.4) are considered. The resulting V CI represents an almost Gaussian profile clearly distinguishable from its shape in the models of the pure [3,4,7,8] or kinetically modified [1,2,[23][24][25] nMI where an almost flat plateau emerges in EF-see Sect. 4.2 too.…”

“…(2.1) and (2.2) along the lines of Ref. [23] we end up with the JF potential V CI = 2 V CI /N 2 in Eq. (1.1) with the function − /N = f R acting as a frame function.…”