## Title: *Lattice Simulations of Abelian Gauge Fields coupled to Axion during Inflation*
## Reporter: Cheng-Jie Fu
| 11.25| 10.00 AM | 6420 | Gong Cheng |
## Title: *Cross-correlating Astrophysical and Cosmological Gravitational Wave Backgrounds with the Cosmic Microwave Background*
## Reporter: Gong Cheng
## Abstract
In this talk, I will introduce the non-linear lattice simulation for a model of axion inflation where the inflaton is coupled to a U(1) gauge field through Chern-Simons interaction.
In this letter the authors explore the cross-correlation of the cosmological and astrophysical SGWBs with CMB anisotropies, showing that future GW detectors, such as LISA or BBO, have the ability to measure such cross-correlation signals. Also, they present constrained realization maps of the SGWBs extracted from the high-resolution CMB Planck maps. This technique allows, in the low-noise regime, to faithfully reconstruct the expected SGWB map by starting from CMB measurements.
## References
-[Arxiv:2110.10695](https://arxiv.org/abs/2110.10695)*Lattice Simulations of Abelian Gauge Fields coupled to Axion during Inflation* by *Angelo Caravano* at al.
-[Arxiv:2106.02591](https://arxiv.org/abs/2106.02591)*Cross-correlating Astrophysical and Cosmological Gravitational Wave Backgrounds with the Cosmic Microwave Background* by *A. Ricciardone* at al.
## Title: *On the integrability conjecture during transient resonance in extreme-mass-ratio inspirals*
## Reporter: Yota Watanabe
| 11.25 | 2.30 PM | 6420 | Shao-Jiang Wang |
## Title: *Cosmic inflation from broken conformal symmetry*
## Reporter: Shao-Jiang Wang
## Abstract
An extreme-mass-ratio inspiral is driven by the self-force and may encounter the r-theta resonance when the ratio of its radial and polar frequencies are rational. There is a conjecture which states that the r-theta transient resonance is driven not by the conservative but by the dissipative self-force. This so-called integrability conjecture is still the subject of controversy in the literature. In this group seminar, I will argue to disprove this conjecture.
A period of rapidly accelerating expansion is expected in the early Universe implemented by a scalar field slowly rolling down along an asymptotically flat potential preferred by the current data. In this paper, we point out that this picture of the cosmic inflation with an asymptotically flat potential could emerge from the Palatini quadratic gravity by adding the matter field in such a way to break the local gauged conformal symmetry in both kinetic and potential terms. The metric Einstein gravity with a positive cosmological constant could be recovered either in the absence of the matter field or by adding the matter field in a way that preserves the local gauged conformal symmetry.
## References
<!-- - [Arxiv:2101.01282](https://arxiv.org/abs/2101.01282)*A cuspy dark matter halo* by *Yong Shi* et al.
-[Arxiv:2109.01402](https://arxiv.org/abs/2109.01402)*A shallow dark matter halo in Ultra Diffuse Galaxy AGC 242019: are UDGs structurally similar to low surface brightness galaxies?* by *Chris B.Brook* et al. -->
-[Arxiv:2110.14718](https://arxiv.org/abs/2110.14718)*Cosmic inflation from broken conformal symmetry* by *Rong-Gen Cai, Yu-Shi Hao* and *Shao-Jiang Wang*.
<!-- - [Arxiv:2109.01402](https://arxiv.org/abs/2109.01402) *A shallow dark matter halo in Ultra Diffuse Galaxy AGC 242019: are UDGs structurally similar to low surface brightness galaxies?* by *Chris B.Brook* et al. -->