Gauge and gravitational instantons: from 3-forms and fermions to weak gravity and flat axion potentials
Abstract We investigate the role of gauge and gravitational instantons in the context of the Swampland program. Our focus is on the global symmetry breaking they induce, especially in the presence of fermions. We first recall and make more precise the description of the dilute instanton gas through...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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SpringerOpen
2019-09-01
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| Series: | Journal of High Energy Physics |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1007/JHEP09(2019)038 |
| _version_ | 1818161042696437760 |
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| author | Arthur Hebecker Philipp Henkenjohann |
| author_facet | Arthur Hebecker Philipp Henkenjohann |
| author_sort | Arthur Hebecker |
| collection | DOAJ |
| description | Abstract We investigate the role of gauge and gravitational instantons in the context of the Swampland program. Our focus is on the global symmetry breaking they induce, especially in the presence of fermions. We first recall and make more precise the description of the dilute instanton gas through a 3-form gauge theory. In this language, the familiar suppression of instanton effects by light fermions can be understood as the decoupling of the 3-form. Even if all fermions remain massive, such decoupling may occur on the basis of an explicitly unbroken but anomalous global symmetry in the fermionic sector. This should be forbidden by quantum gravity, which leads us to conjecture a related, cutoff-dependent lower bound on the induced axion potential. Finally, we note that the gravitational counterpart of the above are K3 instantons. These are small fluctuations of Euclidean spacetime with K3 topology, which induce fermionic operators analogous to the ’t Hooft vertex in gauge theories. Although Planck-suppressed, they may be phenomenologically relevant if accompanied by other higher-dimension fermion operators or if the K3 carries appropriate gauge fluxes. |
| first_indexed | 2024-12-11T16:11:29Z |
| format | Article |
| id | doaj.art-ce91454e28644e33ad4678d92fadb8bc |
| institution | Directory Open Access Journal |
| issn | 1029-8479 |
| language | English |
| last_indexed | 2024-12-11T16:11:29Z |
| publishDate | 2019-09-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Journal of High Energy Physics |
| spelling | doaj.art-ce91454e28644e33ad4678d92fadb8bc2022-12-22T00:59:04ZengSpringerOpenJournal of High Energy Physics1029-84792019-09-012019914210.1007/JHEP09(2019)038Gauge and gravitational instantons: from 3-forms and fermions to weak gravity and flat axion potentialsArthur Hebecker0Philipp Henkenjohann1Institut für Theoretische Physik, Universität HeidelbergInstitut für Theoretische Physik, Universität HeidelbergAbstract We investigate the role of gauge and gravitational instantons in the context of the Swampland program. Our focus is on the global symmetry breaking they induce, especially in the presence of fermions. We first recall and make more precise the description of the dilute instanton gas through a 3-form gauge theory. In this language, the familiar suppression of instanton effects by light fermions can be understood as the decoupling of the 3-form. Even if all fermions remain massive, such decoupling may occur on the basis of an explicitly unbroken but anomalous global symmetry in the fermionic sector. This should be forbidden by quantum gravity, which leads us to conjecture a related, cutoff-dependent lower bound on the induced axion potential. Finally, we note that the gravitational counterpart of the above are K3 instantons. These are small fluctuations of Euclidean spacetime with K3 topology, which induce fermionic operators analogous to the ’t Hooft vertex in gauge theories. Although Planck-suppressed, they may be phenomenologically relevant if accompanied by other higher-dimension fermion operators or if the K3 carries appropriate gauge fluxes.http://link.springer.com/article/10.1007/JHEP09(2019)038Effective Field TheoriesGlobal SymmetriesSuperstring VacuaSolitons Monopoles and Instantons |
| spellingShingle | Arthur Hebecker Philipp Henkenjohann Gauge and gravitational instantons: from 3-forms and fermions to weak gravity and flat axion potentials Journal of High Energy Physics Effective Field Theories Global Symmetries Superstring Vacua Solitons Monopoles and Instantons |
| title | Gauge and gravitational instantons: from 3-forms and fermions to weak gravity and flat axion potentials |
| title_full | Gauge and gravitational instantons: from 3-forms and fermions to weak gravity and flat axion potentials |
| title_fullStr | Gauge and gravitational instantons: from 3-forms and fermions to weak gravity and flat axion potentials |
| title_full_unstemmed | Gauge and gravitational instantons: from 3-forms and fermions to weak gravity and flat axion potentials |
| title_short | Gauge and gravitational instantons: from 3-forms and fermions to weak gravity and flat axion potentials |
| title_sort | gauge and gravitational instantons from 3 forms and fermions to weak gravity and flat axion potentials |
| topic | Effective Field Theories Global Symmetries Superstring Vacua Solitons Monopoles and Instantons |
| url | http://link.springer.com/article/10.1007/JHEP09(2019)038 |
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