2023 Fiscal Year Annual Research Report
Probing the early universe by stochastic gravitational wave background
| Project/Area Number |
20K14461
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| Research Institution | The University of Tokyo |
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Principal Investigator |
皮 石 東京大学, カブリ数物連携宇宙研究機構, 客員准科学研究員 (60817518)
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| Project Period (FY) |
2020-04-01 – 2024-03-31
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| Keywords | gravitational waves / primordial black holes / curvature perturbation / inflation / ultra slow roll / δN formalism / pulsar timing array / LISA |
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| Outline of Annual Research Achievements |
In the entire period of this program JP20K14461, I completed 13 papers (10 published, 3 in submission). Here is a summary of some representitive works.
1. Pi and Sasaki, Phys.Rev.Lett. 131 (2023) 1, 011002. We found a fully nonlinear expression for the curvature perturbation in single-field inflation models, which is very helpful in determining its statistical properties.
2. Cai, Pi, and Sasaki, Phys.Rev.D 102 (2020) 8, 083528. We show that under some general conditions, the GW spectra, no matter what sources they come from, has an universal infrared f^3 scaling.
3. Demenech and Pi, Sci.China Phys.Mech.Astron. 65 (2022) 3, 230411. We show that the nHz GW signal observed by pulsar timing arrays (NANOGrav, etc.) could indicate the presense of planet-mass PBHs.
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