Completing natural inflation

By Jihn E. Kim, H. Nilles, Marco Peloso. 2004

533 citations recorded by the source corpus.

If the inflaton is a pseudo-scalar axion, the axion shift symmetry can protect the flatness of its potential from too large radiative corrections. This possibility, known as natural inflation, requires an axion scale which is greater than the (reduced) Planck scale. It is unclear whether such a high value is compatible with an effective field theoretical description, and whether the global axionic symmetry survives quantum gravity effects. We propose a mechanism which provides an effective large axion scale, although the original one is sub-Planckian. The mechanism is based on the presence of two axions, with a potential provided by two anomalous gauge groups. The effective large axion scale is due to an almost exact symmetry between the couplings of the axions to the anomalous groups. We also comment on a possible implementation in heterotic string theory.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/d370951160ee2e4a3f39b61f5a491f7addf1cca8

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Citations in the corpus

Phenomenology of a pseudo-scalar inflaton: naturally large nongaussianity (2011, background): “The idea of using a PNGB as inflaton was first put forward in [6]; in this minimal realization a single axion is present; it turns out that this model can produce a sufficiently flat spectrum of perturbations only if the axion decay constant f is above the Planck scale.”
Recent Progress in the Physics of Axions and Axion-Like Particles (2020, background): “Our first example is a two axion model (NH = NL = 1) realizing the KNP alignment mechanism proposed to enlarge the monotonic field range of the light axion [26, 129].”
The Swampland: Introduction and Review (2019, background): “Such long field paths are of interest for inflation models, and the first construction of an axion alignment model was motivated by this [152].”
Fencing in the swampland: quantum gravity constraints on large field inflation (2015, background): “The idea is essentially that while each axion decay constant must be sub-Planckian, the net effective decay constant may be larger, as in the alignment [6] or N-flation [7] scenarios.”
Transplanckian axions!? (2015, background): “However for models based on lattice alignment [8], parametrically large field ranges also receive unsuppressed higher harmonic contributions and the results are similar to the single axion case: gravitational instantons jeopardize inflationary transplanckian field ranges.”
Winding out of the Swamp: Evading the Weak Gravity Conjecture with F-term Winding Inflation? (2015, methodology): “The idea of achieving a long direction due to winding trajectories in the field space of two axions was proposed in [3] and subsequently many large-field inflation models in string theory have employed this mechanism [5,17,19,20,27,33,34].”
Gravity Waves and Linear Inflation from Axion Monodromy (2008, background): “However, in the case of axions it has been argued that the field range contained within a single period is generally sub-Planckian in string theory [8], leading to proposals to extend the field range by combining many axions [9].”
A review of axion inflation in the era of Planck (2013, background): “The first implementation of this idea was given in [30] where it was assumed that two axions are present and they interact through some non-perturbative potential”
Two-field high-scale inflation in a sub-Planckian region of field space (2009, background): “Kim, Nilles and Peloso [5] proposed an interesting twofield model (based on [6]) that also has the two properties of the previous paragraphs.”