Studies of the magnetic fields in our universe provide an excellent opportunity to confront monopoles with astrophysical observations. I will discuss two projects along this line: (1) New Parker-type bounds on the monopole flux in light of the modern understanding of cosmological magnetic fields, including galactic, intergalactic, and primordial fields. I will also present constraints on...
We present a novel mechanism for the formation of topologically stable monopoles with two unit of Dirac magnetic charges from the decay of metastable string network in an SO(10) GUT. Superheavy monopoles (masses ~ 1015 – 1017 GeV) can be produced with an observable flux from a string network with the dimensionless tension Gμ ~ 10-9-10-5 (μ is the string tension and G the Newton’s constant) in...
This study presents a detailed investigation into the formation and dynamics of topological defects, particularly domain walls, resulting from the breaking of discrete symmetries within scalar field theories. By focusing on the effects of parametric resonance, we investigate the mechanisms driving symmetry restoration and the subsequent emergence of domain walls. Through the analysis of a...
We study superhorizon production of dark matter particles from quantum fluctuations of a spectator field during inflation. The dark matter density contrast has O(1) fluctuations in this type of scenarios which is not consistent with the CMB and LSS observations. We thus find the lower bound m>10^{-24} eV on the mass of dark matter particles with momenta k>10/Mpc. This universal bound is...
