Parity-violating scalar trispectrum from a rolling axion during inflation
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| Format: | Preprint |
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2023
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| _version_ | 1866913449578070016 |
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| author | Fujita, Tomohiro Murata, Tomoaki Obata, Ippei Shiraishi, Maresuke |
| author_facet | Fujita, Tomohiro Murata, Tomoaki Obata, Ippei Shiraishi, Maresuke |
| contents | We study a mechanism of generating the trispectrum (4-point correlation) of curvature perturbation through the dynamics of a spectator axion field and U(1) gauge field during inflation. Owing to the Chern-Simons coupling, only one helicity mode of gauge field experiences a tachyonic instability and sources scalar perturbations. Sourced curvature perturbation exhibits parity-violating nature which can be tested through its trispectrum. We numerically compute parity-even and parity-odd component of the sourced trispectrum. It is found that the ratio of parity-odd to parity-even mode can reach O(10%) in an exact equilateral momentum configuration. We also investigate a quasi-equilateral shape where only one of the momenta is slightly longer than the other three, and find that the parity-odd mode can reach, and more interestingly, surpass the parity-even one. This may help us to interpret a large parity-odd trispectrum signal extracted from BOSS galaxy-clustering data. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2310_03551 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Parity-violating scalar trispectrum from a rolling axion during inflation Fujita, Tomohiro Murata, Tomoaki Obata, Ippei Shiraishi, Maresuke Cosmology and Nongalactic Astrophysics We study a mechanism of generating the trispectrum (4-point correlation) of curvature perturbation through the dynamics of a spectator axion field and U(1) gauge field during inflation. Owing to the Chern-Simons coupling, only one helicity mode of gauge field experiences a tachyonic instability and sources scalar perturbations. Sourced curvature perturbation exhibits parity-violating nature which can be tested through its trispectrum. We numerically compute parity-even and parity-odd component of the sourced trispectrum. It is found that the ratio of parity-odd to parity-even mode can reach O(10%) in an exact equilateral momentum configuration. We also investigate a quasi-equilateral shape where only one of the momenta is slightly longer than the other three, and find that the parity-odd mode can reach, and more interestingly, surpass the parity-even one. This may help us to interpret a large parity-odd trispectrum signal extracted from BOSS galaxy-clustering data. |
| title | Parity-violating scalar trispectrum from a rolling axion during inflation |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2310.03551 |