Conformal anomalies and gravitational waves
We argue that the presence of conformal anomalies in gravitational theories can lead to observable modifications to Einstein's equations via the induced anomalous effective actions, whose non-localities can overwhelm the smallness of the Planck scale. The fact that no such effects have been see...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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Elsevier
2017-09-01
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| Series: | Physics Letters B |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0370269317305075 |
| _version_ | 1819231234615672832 |
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| author | Krzysztof A. Meissner Hermann Nicolai |
| author_facet | Krzysztof A. Meissner Hermann Nicolai |
| author_sort | Krzysztof A. Meissner |
| collection | DOAJ |
| description | We argue that the presence of conformal anomalies in gravitational theories can lead to observable modifications to Einstein's equations via the induced anomalous effective actions, whose non-localities can overwhelm the smallness of the Planck scale. The fact that no such effects have been seen in recent cosmological or gravitational wave observations therefore imposes strong restrictions on the field content of possible extensions of Einstein's theory: all viable theories should have vanishing conformal anomalies. We then show that a complete cancellation of conformal anomalies in D=4 for both the C2 invariant and the Euler (Gauss–Bonnet) invariant E4 can only be achieved for N-extended supergravity multiplets with N⩾5, as well as for M theory compactified to four dimensions. Although there remain open questions, in particular concerning the true significance of conformal anomalies in non-conformal theories, as well as their possible gauge dependence for spin s⩾32, these cancellations suggest a hidden conformal structure of unknown type in these theories. |
| first_indexed | 2024-12-23T11:41:44Z |
| format | Article |
| id | doaj.art-f92999012c5642e0ae05ba7ddab8997e |
| institution | Directory Open Access Journal |
| issn | 0370-2693 1873-2445 |
| language | English |
| last_indexed | 2024-12-23T11:41:44Z |
| publishDate | 2017-09-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Physics Letters B |
| spelling | doaj.art-f92999012c5642e0ae05ba7ddab8997e2022-12-21T17:48:27ZengElsevierPhysics Letters B0370-26931873-24452017-09-01772C16917310.1016/j.physletb.2017.06.031Conformal anomalies and gravitational wavesKrzysztof A. Meissner0Hermann Nicolai1Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, PolandMax-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut), Mühlenberg 1, D-14476 Potsdam, GermanyWe argue that the presence of conformal anomalies in gravitational theories can lead to observable modifications to Einstein's equations via the induced anomalous effective actions, whose non-localities can overwhelm the smallness of the Planck scale. The fact that no such effects have been seen in recent cosmological or gravitational wave observations therefore imposes strong restrictions on the field content of possible extensions of Einstein's theory: all viable theories should have vanishing conformal anomalies. We then show that a complete cancellation of conformal anomalies in D=4 for both the C2 invariant and the Euler (Gauss–Bonnet) invariant E4 can only be achieved for N-extended supergravity multiplets with N⩾5, as well as for M theory compactified to four dimensions. Although there remain open questions, in particular concerning the true significance of conformal anomalies in non-conformal theories, as well as their possible gauge dependence for spin s⩾32, these cancellations suggest a hidden conformal structure of unknown type in these theories.http://www.sciencedirect.com/science/article/pii/S0370269317305075 |
| spellingShingle | Krzysztof A. Meissner Hermann Nicolai Conformal anomalies and gravitational waves Physics Letters B |
| title | Conformal anomalies and gravitational waves |
| title_full | Conformal anomalies and gravitational waves |
| title_fullStr | Conformal anomalies and gravitational waves |
| title_full_unstemmed | Conformal anomalies and gravitational waves |
| title_short | Conformal anomalies and gravitational waves |
| title_sort | conformal anomalies and gravitational waves |
| url | http://www.sciencedirect.com/science/article/pii/S0370269317305075 |
| work_keys_str_mv | AT krzysztofameissner conformalanomaliesandgravitationalwaves AT hermannnicolai conformalanomaliesandgravitationalwaves |