Consequences of the Phase Transitions Happened during Inflation

by Prof. Haipeng An (Tsinghua University)

Thursday 13 Jun 2024, 10:00 → 12:00 Asia/Shanghai

Tsung-Dao Lee Institute/N6F-N600 - Lecture Room (Tsung-Dao Lee Institute)

Abstract: 

During the inflationary era, the properties (such as mass and interactions) of fields coupled to the inflaton field may change substantially. As a result, drastic phenomena, such as phase transitions, may occur. In this talk, I will present simple models where phase transitions can happen and conclude during inflation. I will discuss the properties of gravitational wave (GW) signals resulting from first-order phase transitions, highlighting a unique oscillatory feature in the GW spectrum. Additionally, I will explore the production of topological defects, such as domain walls, which may arise from second-order phase transitions. We will examine the properties of GWs produced by domain walls during inflation without forming a network.To provide a comprehensive understanding, we numerically simulate domain wall production caused by a second-order phase transition and calculate the GW spectrum using a classical lattice approach. Our findings indicate that GWs produced through first- or second-order phase transitions can be observed directly by future terrestrial and space-based gravitational wave detectors, as well as through the B-mode spectrum in the Cosmic Microwave Background (CMB). Moreover, these signals can potentially explain the common noise process observed by pulsar timing array experiments. The details of the GW spectra also contain valuable information about the evolution of the universe. Furthermore, phase transitions during inflation can lead to the production of baryon number and dark matter, which I will also discuss in my talk.

Biography: 

Haipeng An received his BSc degrees in Physics and Mathematics from Peking University in 2006. He earned his PhD in Physics from the University of Maryland in 2011. Following his doctoral studies, he worked as a postdoctoral fellow at the Perimeter Institute for Theoretical Physics from 2011 to 2014. He then moved to Caltech, where he served as a Walter Burke Postdoctoral Fellow from 2014 to 2017. In 2017, he joined the faculty at Tsinghua University.

 

Alternative online link:  https://meeting.tencent.com/dm/GxRfkXtYttAx 

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