arXiv subjects

Vincent B. Klaer

Publications and source records attributed to Vincent B. Klaer.

3 recordsLinked to original sources

arXiv2020

Global cosmic string networks as a function of tension

We investigate the properties of global cosmic string networks as a function of the ratio of string tension to Goldstone-field coupling, and as a function of the Hubble damping strength. Our results show unambiguously that the string density is sensitive to this ratio. We also find that existing semi-analytical (one-scale) models must be missing some important aspect of the network dynamics. Our results point the way towards improving such models.

hep-ph↗

arXiv2017

The dark-matter axion mass

We evaluate the efficiency of axion production from spatially random initial conditions in the axion field, so a network of axionic strings is present. For the first time, we perform numerical simulations which fully account for the large short-distance contributions to the axionic string tension, and the resulting dense network of high-tension axionic strings. We find nevertheless that the total axion production is somewhat less efficient than in the angle-averaged misalignment case. Combining our results with a recent determination of the hot QCD topological susceptibility (Borsanyi et al 2016), we find that if the axion makes up all of the dark matter, then the axion mass is m_a = 26.2 +-3.4 micro-electron volts.

hep-ph↗

arXiv2017

How to simulate global cosmic strings with large string tension

Global string networks may be relevant in axion production in the early Universe, as well as other cosmological scenarios. Such networks contain a large hierarchy of scales between the string core scale and the Hubble scale, log(f/H) around 70, which influences the network dynamics by giving the strings large tensions T = pi f^2 log(f/H). We present a new numerical approach to simulate such global string networks, capturing the tension without an exponentially large lattice.

hep-ph↗