Abstract
We revisit supersymmetric hybrid inflation in the context of flipped $SU(5)$ model. With minimal superpotential and minimal K\"ahler potential, and soft SUSY masses of order $(1 - 100)$ TeV, compatibility with the Planck data yields a symmetry breaking scale $M$ of flipped $SU(5)$ close to $(2 - 4) \times 10^{15}$ GeV. This disagrees with the lower limit $M \gtrsim 7 \times 10^{15}$ GeV set from proton decay searches by the Super-Kamiokande collaboration. We show how $M$ close to the unification scale $2\times 10^{16}$ GeV can be reconciled with SUSY hybrid inflation by employing a non-minimal K\"ahler potential. Proton decays into $e^+ \pi^0$ with an estimated lifetime of order $10^{36}$ years. The tensor to scalar ratio $r$ in this case can approach observable values $\sim 10^{-4} - 10^{-3}$.
Highlights
The supersymmetric (SUSY) hybrid inflation model [1–5] has attracted a fair amount of attention due to its simplicity and elegance in realizing the grand unified theory (GUT) models of inflation [5]
The important task is to explore the possibility of realizing the gauge symmetry breaking scale M close to a typical GUT scale ∼2 × 1016 GeV
The minimal Higgs sector of flipped SUð5Þ ≡ FSUð5Þ ≡ SUð5Þ × Uð1ÞX consists of a pair of Higgs superfields (10H; 1 ̄0H), and a second pair of 5-plet Higgs superfields (5h, 5 ̄h), which are decomposed under the standard model (SM) gauge group as
Summary
The supersymmetric (SUSY) hybrid inflation model [1–5] has attracted a fair amount of attention due to its simplicity and elegance in realizing the grand unified theory (GUT) models of inflation [5]. Investigate the possibility of realizing large enough M in the SUSY hybrid inflation model with minimal Kähler potential, including various important corrections [1,3,5–7]. It lacks the monopole problem that appears in the spontaneous breaking of other GUT gauge groups [i.e., SUð5Þ, SUð4ÞC × SUð2ÞL × SUð2ÞR or SOð10Þ] This property makes the flipped SUð5Þ model an appropriate choice for the standard version of SUSY hybrid inflation where gauge symmetry is broken after the end of inflation. The prediction of primordial gravitational waves is a generic feature of the inflation paradigm and originates from the quantum nature of gravity These gravity waves are expected to be observed indirectly through the detection of B-mode polarization data in the cosmic microwave background anisotropies.
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