Triangle Seminars
Thursday, 3 Sep 2026
Axions, Monopoles, and Gravity
📍 London
Yu Komiya
(Kyoto)
Abstract:
Phenomenological interest in axions originated from its potential to solve long-standing questions including the strong CP problem, their position as a candidate of dark matter, and their natural introduction through string compactifications. As several models appear to contain sequential symmetry breaking, the potential effects of axion theories on cosmology through their prediction of early universe defect formation gained it cosmological attention. These defects are expected to contain information about the theory’s vacuum structure, to link to the formation of primordial black holes, and to produce detectable signals through the catalysis of exotic processes. This talk reviews the modern intrigue of axion cosmology, and explores the unique effect of an axionic background on monopoles, which is thought to be able to form a stable state in flat space. The consequences of introducing gravitational effects to the system is then analysed; the talk summarises with a commentary on the diverse theoretical, phenomenological, cosmological, and astrophysical relevance of such a line of inquiry. Specifically, the UV extension of this topic through the moduli dynamics of the core monopole will be briefly discussed, which might allow a more complete consideration of stability, as well as relate to a more general understanding of defects through the UV link between quantum field theory and gravity.
Phenomenological interest in axions originated from its potential to solve long-standing questions including the strong CP problem, their position as a candidate of dark matter, and their natural introduction through string compactifications. As several models appear to contain sequential symmetry breaking, the potential effects of axion theories on cosmology through their prediction of early universe defect formation gained it cosmological attention. These defects are expected to contain information about the theory’s vacuum structure, to link to the formation of primordial black holes, and to produce detectable signals through the catalysis of exotic processes. This talk reviews the modern intrigue of axion cosmology, and explores the unique effect of an axionic background on monopoles, which is thought to be able to form a stable state in flat space. The consequences of introducing gravitational effects to the system is then analysed; the talk summarises with a commentary on the diverse theoretical, phenomenological, cosmological, and astrophysical relevance of such a line of inquiry. Specifically, the UV extension of this topic through the moduli dynamics of the core monopole will be briefly discussed, which might allow a more complete consideration of stability, as well as relate to a more general understanding of defects through the UV link between quantum field theory and gravity.
Posted by: Kymani Armstrong-Williams
Friday, 4 Sep 2026
A menagerie of Euclidean constructions for 3D holographic cosmologies
📍 London
Alejandro Vilar López
(U. British Columbia)
Abstract:
In this talk, I will introduce a large family of solutions of Euclidean three-dimensional gravity coupled to heavy matter particles that, upon continuation to Lorentzian signature, contain a closed big-bang / big-crunch cosmology entangled with additional asymptotically AdS regions. The construction generalizes the one introduced by Antonini-Sasieta-Swingle (AS2), but the extra analytic control available in three dimensions makes it possible to embed more general cosmologies (e.g., approximately homogeneous and isotropic ones) in a relatively conventional AdS/CFT setup. I will then discuss to what extent these saddles containing a closed universe can dominate the path integral, introducing possible competing geometries, and comment on a general necessary condition for the dominance of the cosmological saddle points.
In this talk, I will introduce a large family of solutions of Euclidean three-dimensional gravity coupled to heavy matter particles that, upon continuation to Lorentzian signature, contain a closed big-bang / big-crunch cosmology entangled with additional asymptotically AdS regions. The construction generalizes the one introduced by Antonini-Sasieta-Swingle (AS2), but the extra analytic control available in three dimensions makes it possible to embed more general cosmologies (e.g., approximately homogeneous and isotropic ones) in a relatively conventional AdS/CFT setup. I will then discuss to what extent these saddles containing a closed universe can dominate the path integral, introducing possible competing geometries, and comment on a general necessary condition for the dominance of the cosmological saddle points.
Posted by: Martin Lagares