Monodromy in the CMB: Gravity Waves and String Inflation

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The sensitivity of inflationary models to Planck-suppressed operators motivates modeling inflation in string theory. The case of high-scale inflation is particularly interesting both theoretically and observationally. Observationally it yields a gravity wave (B mode polarization) signature, and theoretically it requires a large field excursion which is particularly sensitive to UV physics. I\'ll present a simple mechanism derived recently in collaboration with A. Westphal for obtaining large-field inflation, and hence a gravitational wave signature, from string theory. The simplest version of this mechanism, arising on twisted torus compactifications of string theory, yields an observationally distinctive version of chaotic inflation with a potential proportional to the 2/3 power of the inflaton, falsifiable on the basis of upcoming CMB measurements. This mechanism for extending the field range arises widely in string compactifications, though in all cases it requires sufficient symmetry to control the corrections to the slow-roll parameters. I will finish by describing further developments in this direction.