Nagoya University
Theoretical Elementary Particle Physics Laboratory

Date&Time Mon May 22 2023 (14:45 - 15:45)
Speaker
Naoya Kitajima
Affiliation Tohoku University
Title Emission of dark photons and gravitational waves from cosmic string network
Abstract In this talk, I will show the emission of dark photons and gravitational waves from the network of Abelian Higgs cosmic string associated with the spontaneous breaking of U(1) gauge symmetry in the early Universe. In particular, I focus on the case with very light dark photon, i.e., small gauge coupling. In this case, the cosmic string can be regarded as an almost-global string like the axion string. First, I discuss the scaling property of the network, particularly focusing on the number of loops based on numerical simulations. Then, I will show the abundance of dark photon (as dark matter) produced by the collapse of loops. Finally, the gravitational wave emission is discussed. The predicted spectrum is characteristic in the sense that it is different from both two cases: the local (type-I) string and the global (axion) string. We can test the scenario by combining the ground-based, space-based and pulsar timing observations of gravitational waves.
Remarks
Slide/Video video1