Fibre inflation: observable gravity waves from IIB string compactifications

By M. Cicoli, C. Burgess, F. Quevedo. 2008

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We introduce a simple string model of inflation, in which the inflaton field can take trans-Planckian values while driving a period of slow-roll inflation. This leads naturally to a realisation of large field inflation, inasmuch as the inflationary epoch is well described by the single-field scalar potential V = V{sub 0}(3-4e{sup -{phi}/(3){sup 1{sup /{sup 2}}}}). Remarkably, for a broad class of vacua all adjustable parameters enter only through the overall coefficient V{sub 0}, and in particular do not enter into the slow-roll parameters. Consequently these are determined purely by the number of e -foldings, N{sub e}, and so are not independent: {epsilon} {approx_equal} 3/2{eta}{sup 2}. This implies similar relations among observables like the primordial scalar-to-tensor amplitude, r, and the scalar spectral tilt, n{sub s}: r {approx_equal} 6(n{sub s}-1){sup 2}. N{sub e} is itself more model-dependent since it depends partly on the post-inflationary reheat history. In a simple reheating scenario a reheating temperature of T{sub rh} {approx_equal} 10{sup 9} GeV gives N{sub e} {approx_equal} 58, corresponding to n{sub s} {approx_equal} 0.970 and r {approx_equal} 0.005, within reach of future observations. The model is an example of a class that arises naturally in the context of type IIB string compactifications with large-volumemore » moduli stabilisation, and takes advantage of the generic existence there of Kaehler moduli whose dominant appearance in the scalar potential arises from string loop corrections to the Kaehler potential. The inflaton field is a combination of Kaehler moduli of a K3-fibered Calabi-Yau manifold. We believe there are likely to be a great number of models in this class-''high-fibre models''-in which the inflaton starts off far enough up the fibre to produce observably large primordial gravity waves.« less

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/e8b5792ee0502d429ce7b082b17a884e81159260

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Citations in the corpus

CMB-S4 Science Case, Reference Design, and Project Plan (2019, background): “Some particular realizations of physical models in the plateau class are also shown: the Starobinsky model [7] and Higgs inflation [8] (small and large orange filled circles, respectively) and fibre inflation [9] (purple line).”
D-branes at del Pezzo singularities: global embedding and moduli stabilisation (2012, background): “This is important in order to have moduli that can play a rôle for inflation and for having the potential for non-gaussianities [28, 29, 31].”
Inflation and String Theory (2014, methodology): “The first proposal of this sort is fibre inflation [43].”
Primordial black holes from string inflation (2018, background): “J C A P 0 6 ( 2 0 1 8 ) 0 3 4 φ as [31]:”
Planck2018 results (2018, background): “– For the simple one parameter class of inflationary potentials with exponential tails (Goncharov & Linde 1984; Stewart 1995; Dvali & Tye 1999; Burgess et al. 2002; Cicoli et al. 2009) we find ln B = −1.”
Simple exercises to flatten your potential (2010, background): “would like to thank the KITP at UC Santa Barbara for their warm hospitality during the “Strings at the LHC and in It would also be interesting to study backreaction further in models where a cycle size modulus plays the role of the inflaton such as [41] or [42].”
α-attractors: Planck, LHC and dark energy (2015, methodology): “Other models which make related predictions include the fibre inflation model [35] and the Starobinsky-like models developed in [36].”
Testing string vacua in the lab: from a hidden CMB to dark forces in flux compactifications (2011, background): “This direction played the rôle of the inflaton in [61, 62, 63, 64] and can be lifted via subleading contributions to (4.”
Explicit de Sitter flux vacua for global string models with chiral matter (2013, background): “These are the right features to realise different promising models where the inflaton is a Kähler modulus [86–89].”
Backreacted axion field ranges in string theory (2016, unknown): “Moduli fields have been considered as possible candidates for fields that could support super-Planckian excursions, see [14] for a review, [15] for early work and [16] for the most recent.”