On scalaron decay via the trace of energy-momentum tensor
Abstract In some inflation scenarios such as R 2 inflation, a gravitational scalar degrees of freedom called scalaron is identified as inflaton. Scalaron linearly couples to matter via the trace of energy-momentum tensor. We study scenarios with a sequestered matter sector, where the trace of energy...
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| Format: | Article |
| Language: | English |
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SpringerOpen
2019-07-01
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| Series: | Journal of High Energy Physics |
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| Online Access: | http://link.springer.com/article/10.1007/JHEP07(2019)172 |
| _version_ | 1818943359732940800 |
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| author | Ayuki Kamada |
| author_facet | Ayuki Kamada |
| author_sort | Ayuki Kamada |
| collection | DOAJ |
| description | Abstract In some inflation scenarios such as R 2 inflation, a gravitational scalar degrees of freedom called scalaron is identified as inflaton. Scalaron linearly couples to matter via the trace of energy-momentum tensor. We study scenarios with a sequestered matter sector, where the trace of energy-momentum tensor predominantly determines the scalaron coupling to matter. In a sequestered setup, heavy degrees of freedom are expected to decouple from low-energy dynamics. On the other hand, it is non-trivial to see the decoupling since scalaron couples to a mass term of heavy degrees of freedom. Actually, when heavy degrees of freedom carry some gauge charge, the amplitude of scalaron decay to two gauge bosons does not vanish in the heavy mass limit. Here a quantum contribution to the trace of energy-momentum tensor plays an essential role. This quantum contribution is known as trace anomaly or Weyl anomaly. The trace anomaly contribution from heavy degrees of freedom cancels with the contribution from the classical scalaron coupling to a mass term of heavy degrees of freedom. We see how trace anomaly appears both in the Fujikawa method and in dimensional renormalization. In dimensional renormalization, one can evaluate the scalaron decay amplitude in principle at all orders, while it is unclear how to process it beyond the one-loop level in the Fujikawa method. We consider scalaron decay to two gauge bosons via the trace of energy-momentum tensor in quantum electrodynamics with scalars and fermions. We evaluate the decay amplitude at the leading order to demonstrate the decoupling of heavy degrees of freedom. |
| first_indexed | 2024-12-20T07:26:05Z |
| format | Article |
| id | doaj.art-e3e23b946496442aa515a11a166eeae4 |
| institution | Directory Open Access Journal |
| issn | 1029-8479 |
| language | English |
| last_indexed | 2024-12-20T07:26:05Z |
| publishDate | 2019-07-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Journal of High Energy Physics |
| spelling | doaj.art-e3e23b946496442aa515a11a166eeae42022-12-21T19:48:33ZengSpringerOpenJournal of High Energy Physics1029-84792019-07-012019712710.1007/JHEP07(2019)172On scalaron decay via the trace of energy-momentum tensorAyuki Kamada0Center for Theoretical Physics of the Universe, Institute for Basic Science (IBS)Abstract In some inflation scenarios such as R 2 inflation, a gravitational scalar degrees of freedom called scalaron is identified as inflaton. Scalaron linearly couples to matter via the trace of energy-momentum tensor. We study scenarios with a sequestered matter sector, where the trace of energy-momentum tensor predominantly determines the scalaron coupling to matter. In a sequestered setup, heavy degrees of freedom are expected to decouple from low-energy dynamics. On the other hand, it is non-trivial to see the decoupling since scalaron couples to a mass term of heavy degrees of freedom. Actually, when heavy degrees of freedom carry some gauge charge, the amplitude of scalaron decay to two gauge bosons does not vanish in the heavy mass limit. Here a quantum contribution to the trace of energy-momentum tensor plays an essential role. This quantum contribution is known as trace anomaly or Weyl anomaly. The trace anomaly contribution from heavy degrees of freedom cancels with the contribution from the classical scalaron coupling to a mass term of heavy degrees of freedom. We see how trace anomaly appears both in the Fujikawa method and in dimensional renormalization. In dimensional renormalization, one can evaluate the scalaron decay amplitude in principle at all orders, while it is unclear how to process it beyond the one-loop level in the Fujikawa method. We consider scalaron decay to two gauge bosons via the trace of energy-momentum tensor in quantum electrodynamics with scalars and fermions. We evaluate the decay amplitude at the leading order to demonstrate the decoupling of heavy degrees of freedom.http://link.springer.com/article/10.1007/JHEP07(2019)172Anomalies in Field and String TheoriesCosmology of Theories beyond the SM |
| spellingShingle | Ayuki Kamada On scalaron decay via the trace of energy-momentum tensor Journal of High Energy Physics Anomalies in Field and String Theories Cosmology of Theories beyond the SM |
| title | On scalaron decay via the trace of energy-momentum tensor |
| title_full | On scalaron decay via the trace of energy-momentum tensor |
| title_fullStr | On scalaron decay via the trace of energy-momentum tensor |
| title_full_unstemmed | On scalaron decay via the trace of energy-momentum tensor |
| title_short | On scalaron decay via the trace of energy-momentum tensor |
| title_sort | on scalaron decay via the trace of energy momentum tensor |
| topic | Anomalies in Field and String Theories Cosmology of Theories beyond the SM |
| url | http://link.springer.com/article/10.1007/JHEP07(2019)172 |
| work_keys_str_mv | AT ayukikamada onscalarondecayviathetraceofenergymomentumtensor |