Metastable cosmic strings produce a gravitational wave background that is best modeled with three parameters (string tension Gμ plus independent time scales t_LB and t_NC), yielding a compact analytical spectrum when t_LB greatly exceeds t_NC.
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Probing the pre-BBN universe with gravitational waves from cosmic strings
Canonical reference. 100% of citing Pith papers cite this work as background.
abstract
Many motivated extensions of the Standard Model predict the existence of cosmic strings. Gravitational waves originating from the dynamics of the resulting cosmic string network have the ability to probe many otherwise inaccessible properties of the early universe. In this study we show how the spectrum of gravitational waves from a cosmic string network can be used to test the equation of state of the early universe prior to Big Bang Nucleosynthesis (BBN). We also demonstrate that current and planned gravitational wave detectors such as LIGO, LISA, DECIGO/BBO, and ET/CE have the potential to detect signals of a non-standard pre-BBN equation of state and evolution of the early universe (e.g., early non-standard matter domination or kination domination) or new degrees of freedom active in the early universe beyond the sensitivity of terrestrial collider experiments and cosmic microwave background measurements.
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Supersymmetry with heavy particles above ~10^5 GeV enhances asteroid-mass PBH production via transient equation-of-state softening, allowing them to comprise all dark matter unlike in the Standard Model.
Gauged U(1)_F flavor symmetries shield the axion from quantum gravity corrections, yielding unit domain wall number and a plateau-valley GW spectrum from flavonic and axionic strings as a probe of flavored axion dark matter.
Analytical approximations for the ultra-high-frequency GW peak sourced by friction-era cosmic string loops, with expanded observable parameter space.
In gauged U(1) completions enabling high-quality axion dark matter, cosmic string loops generate a stochastic gravitational wave background with an infrared break frequency that exceeds foregrounds above 10^14 GeV breaking scales and offers a probe at interferometers.
During chiral plasma instability, excess energy from chiral asymmetry heats the plasma with δT ~ μ5²/T instead of fully building the helical magnetic field.
High-quality axion models with N_DW=1 and dark matter abundance requirement restrict the gauge breaking scale to 1.6e11-1e16 GeV, yielding a band of gravitational wave signals from two-step phase transitions consistent with current observations.
Majoron dark matter is viable for sub-MeV masses in high-scale seesaw models with thermal leptogenesis, produced via misalignment and cosmic strings in pre- and post-inflationary scenarios and constrained by CMB, X-ray, and gravitational wave observations.
Hybrid string-bounded domain wall networks from sequential U(1)_F and Z2 symmetry breaking generate a GW spectrum with a unique low-frequency slope that future detectors can observe and an MLP surrogate can characterize for fast SNR inference.
Cosmic string networks are constrained to less than ~1% of the energy density using CMB+BAO+SN data, with some models preferring mildly negative densities but no Bayesian evidence favoring them over LambdaCDM.
A review of existing waveform models for LISA sources and the challenges that must still be overcome.
citing papers explorer
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Gravitational waves from cosmic strings with friction: analytical approximations and parameter space
Analytical approximations for the ultra-high-frequency GW peak sourced by friction-era cosmic string loops, with expanded observable parameter space.
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Gravitational Waves from hybrid defects as probe of Flavor symmetry breaking: Machine-Learning Approach
Hybrid string-bounded domain wall networks from sequential U(1)_F and Z2 symmetry breaking generate a GW spectrum with a unique low-frequency slope that future detectors can observe and an MLP surrogate can characterize for fast SNR inference.
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Cosmic Strings as Dynamical Dark Energy: Novel Constraints
Cosmic string networks are constrained to less than ~1% of the energy density using CMB+BAO+SN data, with some models preferring mildly negative densities but no Bayesian evidence favoring them over LambdaCDM.