Landscaping the strong CP problem
Abstract One often hears that the strong CP problem is the one problem which cannot be solved by anthropic reasoning. We argue that this is not so. Due to nonperturbative dynamics, states with a different CP violating paramenter θ acquire different vacuum energies after the QCD phase transition. The...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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SpringerOpen
2019-03-01
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| Series: | Journal of High Energy Physics |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1007/JHEP03(2019)032 |
| _version_ | 1818033803489181696 |
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| author | Nemanja Kaloper John Terning |
| author_facet | Nemanja Kaloper John Terning |
| author_sort | Nemanja Kaloper |
| collection | DOAJ |
| description | Abstract One often hears that the strong CP problem is the one problem which cannot be solved by anthropic reasoning. We argue that this is not so. Due to nonperturbative dynamics, states with a different CP violating paramenter θ acquire different vacuum energies after the QCD phase transition. These add to the total variation of the cosmological constant in the putative landscape of Universes. An interesting possibility arises when the cosmological constant is mostly cancelled by the membrane nucleation mechanism. If the step size in the resulting discretuum of cosmological constants, ΔΛ, is in the interval (meV)4 < ΔΛ < (100 MeV)4, the cancellation of vacuum energy can be assisted by the scanning of θ. For (meV)4 < ΔΛ < (keV)4 this may yield θ < 10−10, meeting the observational limits. This scenario opens up 24 orders of magnitude of acceptable parameter space for ΔΛ compared to membrane nucleation acting alone. In such a Universe one may not need a light axion to solve the strong CP problem. |
| first_indexed | 2024-12-10T06:29:04Z |
| format | Article |
| id | doaj.art-69923745dfe843159461b1e3dcf63f25 |
| institution | Directory Open Access Journal |
| issn | 1029-8479 |
| language | English |
| last_indexed | 2024-12-10T06:29:04Z |
| publishDate | 2019-03-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Journal of High Energy Physics |
| spelling | doaj.art-69923745dfe843159461b1e3dcf63f252022-12-22T01:59:08ZengSpringerOpenJournal of High Energy Physics1029-84792019-03-012019311210.1007/JHEP03(2019)032Landscaping the strong CP problemNemanja Kaloper0John Terning1Department of Physics, University of CaliforniaDepartment of Physics, University of CaliforniaAbstract One often hears that the strong CP problem is the one problem which cannot be solved by anthropic reasoning. We argue that this is not so. Due to nonperturbative dynamics, states with a different CP violating paramenter θ acquire different vacuum energies after the QCD phase transition. These add to the total variation of the cosmological constant in the putative landscape of Universes. An interesting possibility arises when the cosmological constant is mostly cancelled by the membrane nucleation mechanism. If the step size in the resulting discretuum of cosmological constants, ΔΛ, is in the interval (meV)4 < ΔΛ < (100 MeV)4, the cancellation of vacuum energy can be assisted by the scanning of θ. For (meV)4 < ΔΛ < (keV)4 this may yield θ < 10−10, meeting the observational limits. This scenario opens up 24 orders of magnitude of acceptable parameter space for ΔΛ compared to membrane nucleation acting alone. In such a Universe one may not need a light axion to solve the strong CP problem.http://link.springer.com/article/10.1007/JHEP03(2019)032Cosmology of Theories beyond the SMFlux compactificationsPhase Diagram of QCD |
| spellingShingle | Nemanja Kaloper John Terning Landscaping the strong CP problem Journal of High Energy Physics Cosmology of Theories beyond the SM Flux compactifications Phase Diagram of QCD |
| title | Landscaping the strong CP problem |
| title_full | Landscaping the strong CP problem |
| title_fullStr | Landscaping the strong CP problem |
| title_full_unstemmed | Landscaping the strong CP problem |
| title_short | Landscaping the strong CP problem |
| title_sort | landscaping the strong cp problem |
| topic | Cosmology of Theories beyond the SM Flux compactifications Phase Diagram of QCD |
| url | http://link.springer.com/article/10.1007/JHEP03(2019)032 |
| work_keys_str_mv | AT nemanjakaloper landscapingthestrongcpproblem AT johnterning landscapingthestrongcpproblem |