题   目： New inflationary probes of axion dark matter

报告人： Lingfeng Li  博士后 Brown University

时   间： 2023年5月18号（星期四）上午10：00

地   点： 腾讯会议：269-473-216

邀请人： 边立功

报告摘要：If a light axion is present during inflation and becomes part of dark matter afterwards, its quantum fluctuations contribute to dark matter isocurvature. In this article, we introduce a whole new suite of cosmological observables for axion isocurvature, which could help test the presence of axions, as well as its coupling to the inflaton and other heavy spectator fields during inflation such as the radial mode of the Peccei-Quinn field. They include correlated clock signals in the curvature and isocurvature spectra, and mixed cosmological-collider non-Gaussianities involving both curvature and isocurvature fluctuations with shapes and running unconstrained by the current data analyses. Taking into account of the existing strong constraints on axion isocurvature fluctuations from the CMB, these novel signals could still be sizable and potentially observable. In some models, the signals, if observed, could even help us significantly narrow down the range of the inflationary Hubble scale, a crucial parameter difficult to be determined in general, independent of the tensor mode.

报告人介绍：Lingfeng Li received his BS in Chemistry and Physics in 2013 from Peking University, followed by his PhD in Theoretical High Energy Physics from University of California, Davis in 2018 under the supervision of Prof. Hsin-Chia Cheng. Then he joined HKUST IAS as a Postdoctoral Fellow till 2021. Currently, he works as a postdoc at Brown University. He is interested in various models that leave all sorts of signatures in collider phenomenology, cosmology and astrophysics.