2020/02/29 by Tristan Daus, Arthur Hebecker, Sascha Leonhardt +1
Mathematics · Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #Geometry #Gravitation #Homogeneous space #Instanton #Mathematical physics #Mathematics #Noncommutative and Quantum Gravity Theories #Physics #Quantum #Quantum gravity #Quantum mechanics #String theory #Symmetry (geometry) #Theoretical physics #hep-ph #hep-th
paper · pdf · doi:10.1016/j.nuclphysb.2020.115167
23 pages, 2 figures; v3: Appendix on new Euclidean wormhole solution with charged particle added. Extended discussion of other subtopics
openalex publication_date 2020/09/14 · arxiv created 2020/09/21 · arxiv updated 2020/09/22 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
It is widely believed and in part established that exact global symmetries are inconsistent with quantum gravity. One then expects that approximate global symmetries can be quantitatively constrained by quantum gravity or swampland arguments. We provide such a bound for an important class of global symmetries: Those arising from a gauged U(1) with the vector made massive via Higgsing with an axion. The latter necessarily couples to instantons, and their action can be constrained, using both the electric and magnetic version of the axionic weak gravity conjecture, in terms of the cutoff of the theory. As a result, instanton-induced symmetry breaking operators with a suppression factor not smaller than exp(−MP2/Λ2) are present, where Λ is a cutoff of the 4d effective theory. We provide a general argument and clarify the meaning of Λ. Simple 4d and 5d models are presented to illustrate this, and we recall that this is the standard way in which things work out in string compactifications with brane instantons. The relation of our constraint to bounds that can be derived from wormholes or gravitational instantons and to those motivated by black-hole effects at finite temperature are discussed, and we present a generalization of the Giddings-Strominger wormhole solution to the case of a gauge-derived U(1) global symmetry. Finally, we discuss potential loopholes to our arguments.