Search

We consider F-term hybrid inflation (FHI) and SUSY breaking in the context of a B − L extension of the MSSM that largely respects a global U (1) R symmetry. The hidden sector Kaehler manifold enjoys an enhanced S U (1 , 1) / U (1) symmetry, with the scalar curvature determined by the achievement of a SUSY-breaking de Sitter vacuum without undesirable tuning. FHI turns out to be consistent with the data, provided that the magnitude of the emergent soft tadpole term is confined to the range (1.2 – 100) TeV, and it is accompanied by the production of B − L cosmic strings. If these are metastable, they are consistent with the present observations from PTA experiments on the stochastic background of gravitational waves with dimensionless tension G μ cs ≃ (1 − 9.2) · 10 − 8 . The μ parameter of the MSSM arises by appropriately adapting the Giudice–Masiero mechanism and facilitates the out-of-equilibrium decay of the R saxion at a reheat temperature lower than about 71 GeV. Due to the prolonged matter-dominated era, the gravitational wave signal is suppressed at high frequencies. The SUSY mass scale turns out to lie in the PeV region. [ABSTRACT FROM AUTHOR]

We present novel realizations of E-model inflation within Supergravity which are largely associated with the existence of a pole of order one in the kinetic term of the (gauge-singlet) inflaton superfield. This pole arises due to the selected logarithmic Kähler potentials K 1 and K ~ 1 , which parameterize the same hyperbolic manifold with scalar curvature R K = - 2 / N , where (- N) < 0 is the coefficient of a logarithmic term. The associated superpotential W exhibits the same R charge with the inflaton-accompanying superfield and includes all the allowed renormalizable terms. For K = K 1 , inflation can be attained for N = 2 at the cost of some tuning regarding the coefficients of the W terms and predicts a tensor-to-scalar ratio r at the level of 0.001. The tuning can be totally eluded for K = K ~ 1 , which allows for quadratic- and quartic-like models with N values increasing with r and spectral index n s close or even equal to its present central observational value. [ABSTRACT FROM AUTHOR]

Abstract We show that non-minimal inflation, based on the ϕ 4 potential, may be rendered unitarity conserving and compatible with the Planck results for 4.6 ⋅ 10 − 3 ≤ r 21 = c 2 R / c 1 R 2 ≤ 1 , if we introduce a linear contribution (c 1 R ϕ) to the frame function which takes the form f R = 1 + c 1 R ϕ + c 2 R ϕ 2. Supersymmetrization of this model can be achieved by considering two gauge singlet superfields and combining a linear-quadratic superpotential term with a class of logarithmic or semi-logarithmic Kähler potentials with prefactor for the logarithms including the inflaton field − (2 n + 3) or − 2 (n + 1) where − 0.01 ≲ n ≲ 0.013. [ABSTRACT FROM AUTHOR]

We review the realization of Starobinsky-type inflation within induced-gravity supersymmetric (SUSY) and non-SUSY models. In both cases, inflation is in agreement with the current data and can be attained for sub-Planckian values of the inflation. The corresponding effective theories retain perturbative unitarity up to the Planck scale and the inflation mass is predicted to be 3·1013 GeV. The supergravity embedding of these models is achieved by employing two gauge singlet chiral superfields, a superpotential that is uniquely determined by a continuous R and a discrete Zn symmetry and several (semi)logarithmic Kähler potentials that respect these symmetries. Checking various functional forms for the noninflation accompanying field in the Kähler potentials, we identify four cases which stabilize it without invoking higher order terms. [ABSTRACT FROM AUTHOR]

Motivated by the reported discovery of inflationary gravity waves by the Bicep2 experiment, we propose an inflationary scenario in supergravity, based on the standard superpotential used in hybrid inflation. The new model yields a tensor-to-scalar ratio r ≃ 0.14 and scalar spectral index n s ≃ 0.964 , corresponding to quadratic (chaotic) inflation. The important new ingredients are the high-scale, ( 1.6 – 10 ) ⋅ 10 13 GeV , soft supersymmetry breaking mass for the gauge singlet inflaton field and a shift symmetry imposed on the Kähler potential. The end of inflation is accompanied, as in the earlier hybrid inflation models, by the breaking of a gauge symmetry at ( 1.2 – 7.1 ) ⋅ 10 16 GeV , comparable to the grand-unification scale. [ABSTRACT FROM AUTHOR]

Abstract: We explore the upper bound on the tensor-to-scalar ratio r in supersymmetric (F-term) hybrid inflation models with the gauge symmetry breaking scale set equal to the value , as dictated by the unification of the MSSM gauge couplings. We employ a unique renormalizable superpotential and a quasi-canonical Kähler potential, and the scalar spectral index is required to lie within the two-sigma interval from the central value found by the Planck satellite. In a sizable region of the parameter space the potential along the inflationary trajectory is a monotonically increasing function of the inflaton, and for this case, , while the spectral index running, , can be as large as 0.01. Ignoring higher order terms which ensure the boundedness of the potential for large values of the inflaton, the upper bound on r is significantly larger, of order 0.01, for subplanckian values of the inflaton, and . [Copyright &y& Elsevier]

Abstract: The minimal supersymmetric (or F-term) hybrid inflation is defined by a unique renormalizable superpotential, fixed by a R-symmetry, and it employs a canonical Kähler potential. The inflationary potential takes into account both radiative and supergravity corrections, as well as an important soft supersymmetry breaking term, with a mass coefficient in the range . The latter term assists in obtaining a scalar spectral index close to 0.96, as strongly suggested by the PLANCK and WMAP 9 yr measurements. The minimal model predicts that the tensor-to-scalar r is extremely tiny, of order , while the spectral index running, . If inflation is associated with the breaking of a local symmetry, the corresponding symmetry breaking scale M is with . This scenario is compatible with the bounds on M from cosmic strings, formed at the end of inflation from symmetry breaking. We briefly discuss non-thermal leptogenesis which is readily implemented in this class of models. [Copyright &y& Elsevier]

We show that models of chaotic inflation based on the ϕp potential and a linear non-minimal coupling to gravity, fR=1+cRϕ, can be done consistent with data in the context of Supergravity, retaining the perturbative unitarity up to the Planck scale, if we employ logarithmic Kähler potentials with prefactors -p(1+n) or -p(n+1)-1, where -0.035≲n≲0.007 for p=2 or -0.0145≲n≲0.006 for p=4. Focusing, moreover, on a model employing a gauge non-singlet inflaton, we show that a solution to the μ problem of MSSM and baryogenesis via non-thermal leptogenesis can be also accommodated. [ABSTRACT FROM AUTHOR]