PIKIMO 18, University of Kentucky, 19 April 2025

Non-Gaussianity from explicit U(1)-breaking interactions

19 Apr 2025, 11:00

30m

153 (Chemistry Physics (CP) Building )

Morning contributed talks (chairperson R. Hill)

Speaker

Taegyu Lee (Indiana University)

Description

We investigate primordial non-Gaussianity (NG) that arises from explicit $U(1)$ symmetry-breaking interactions during inflation, focusing on a nearly massless axial component of a complex scalar field $P$. We compute the resulting NG parameter $f_{\mathrm{NL}}$, allowing the axial field to act as either a curvaton or cold dark matter (CDM). We consider two scenarios in which the interaction emerges from an explicit $U(1)$ symmetry-breaking potential and from explicit $U(1)$ symmetry-breaking kinetic mixing. We also explore the role of a heavy radial field in generating oscillating correlation signals, noting that such signals can dominate the shape of the mixed adiabatic-isocurvature bispectrum. In certain cases, an oscillatory isocurvature bispectrum signal may be observable in the future, aiding in distinguishing between certain types of the $U(1)$-breaking self-interactions of the axial field.

Presentation materials

PIKIMO18_Taegyu Lee.pdf