Extending and calibrating the velocity dependent one-scale model for cosmic strings with one thousand field theory simulations

Correia, J. R. C. C. C.; Martins, C. J. A. P.

doi:10.1103/physrevd.100.103517

Cited by 43 publications

(68 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A preliminary investigation shows that the more complex model of Ref. [54] does not improve the fit. A more thorough exploration of VOS models and a more accurate estimate of the fixed point could be obtained with a wider range of initial correlation lengths and initial times.…”

Section: Discussionmentioning

confidence: 89%

See 1 more Smart Citation

Approach to scaling in axion string networks

Hindmarsh,

Lizarraga,

Lopez-Eiguren

et al. 2021

Preprint

View full text Add to dashboard Cite

We study the approach to scaling in axion string networks in the radiation era, through measuring the root-mean-square velocity v as well as the scaled mean string separation x. We find good evidence for a fixed point in the phase-space analysis in the variables (x, v), providing a strong indication that standard scaling is taking place. We show that the approach to scaling can be well described by a two parameter velocity-one-scale (VOS) model, and show that the values of the parameters are insensitive to the initial state of the network. The string length has also been commonly expressed in terms of a dimensionless string length density ζ, proportional to the number of Hubble lengths of string per Hubble volume. In simulations with initial conditions far from the fixed point ζ is still evolving after half a light-crossing time, which has been interpreted in the literature as a long-term logarithmic growth. We show that all our simulations, even those starting far from the fixed point, are accounted for by a VOS model with an asymptote of ζ * = 1.20 ± 0.09 (calculated from the string length in the cosmic rest frame) and v * = 0.609 ± 0.014.

show abstract

Section: Discussionmentioning

confidence: 89%

“…We have experimented with fitting for additional parameters q and d (with β = 1 and r = 1) in the VOS model presented in Ref. [54]. but our preliminary analysis shows that the preferred values for these additional parameters are compatible with zero.…”

Section: Fits and Asymptotic Behaviourmentioning

confidence: 99%

Approach to scaling in axion string networks

Hindmarsh,

Lizarraga,

Lopez-Eiguren

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…( 97) is a relativistic generalization of Newton's law where the string is accelerated by its curvature 1/L but is damped by the Hubble expansion and plasma friction after a typical length 1/l d . [132,221], possibly extended to include particle production [176] (dotted line). Right: The corresponding loop-production efficiency for each VOS model.…”

Section: D5 Vos 2: the Mean Velocitymentioning

confidence: 99%

Beyond the Standard Models with cosmic strings

Gouttenoire

Servant

Simakachorn

2020

J. Cosmol. Astropart. Phys.

134

204

View full text Add to dashboard Cite

We examine which information on the early cosmological history can be extracted from the potential measurement by third-generation gravitational-wave observatories of a stochastic gravitational wave background (SGWB) produced by cosmic strings. We consider a variety of cosmological scenarios breaking the scale-invariant properties of the spectrum, such as early long matter or kination eras, short intermediate matter and inflation periods inside a radiation era, and their specific signatures on the SGWB. This requires to go beyond the usually-assumed scaling regime, to take into account the transient effects during the change of equation of state of the universe. We compute the time evolution of the string network parameters and thus the loop-production efficiency during the transient regime, and derive the corresponding shift in the turning-point frequency. We consider the impact of particle production on the gravitational-wave emission by loops. We estimate the reach of future interferometers LISA, BBO, DECIGO, ET and CE and radio telescope SKA to probe the new physics energy scale at which the universe has experienced changes in its expansion history. We find that a given interferometer may be sensitive to very different energy scales, depending on the nature and duration of the non-standard era, and the value of the string tension. It is fascinating that by exploiting the data from different GW observatories associated with distinct frequency bands, we may be able to reconstruct the full spectrum and therefore extract the values of fundamental physics parameters.

show abstract

“…On the other hand, simulations of string networks based on an underlying classical Abelian-Higgs (AH) field theory [17][18][19][20][21][22][23][24] show that the most important decay channel is the production of classical scalar and gauge radiations, in which case the strongest constraints come from a chain of decays into γ-rays. The observed diffuse γ-ray background then limits the string tension to be Gμ < 2.7 × 10 −11 β −2 ft , where β 2 ft is the branching fraction of the scalar and gauge decays into Standard Model particles (most likely the Higgs, through a portal coupling) [25].…”

Section: Introductionmentioning

confidence: 99%

Loop decay in Abelian-Higgs string networks

et al. 2021

View full text Add to dashboard Cite

We study the decay of cosmic string loops in the Abelian-Higgs model. We confirm earlier results that loops formed by intersections of infinite strings formed from random-field initial conditions disappear quickly, with lifetimes proportional to their initial rest-frame length, l init . We study a population with l init up to 6000 inverse mass units and measure the proportionality constant to be 0.14 AE 0.04, independently of the initial lengths. We propose a new method to construct oscillating nonself intersecting loops from initially stationary strings and show that by contrast these loops have lifetimes scaling approximately as l 2 init , in line with previous works on artificially created string configurations. We show that the oscillating strings have a mean-square velocity ofv 2 ≃ 0.500 AE 0.004, consistent with the Nambu-Goto value of 1=2, while the network loops havev 2 ≃ 0.40 AE 0.04. We argue that whatever the mechanism behind the network loop decay is, it is nonlinear, can only be suppressed by careful tuning of initial conditions, and is much stronger than gravitational radiation. An implication is that one cannot use the Nambu-Goto model to derive robust constraints on the tension of field theory strings. We advocate parametrizing the uncertainty as the fraction f NG of Nambu-Goto-like loops surviving to radiate gravitationally. None of the 31 large network loops created survived longer than 0.25 of their initial length, so one can estimate that f NG < 0.1 at 95% confidence level. If the recently reported NANOgrav signal is due to cosmic strings, f NG must be greater than 10 −3 in order not to violate bounds from the cosmic microwave background.

show abstract

Extending and calibrating the velocity dependent one-scale model for cosmic strings with one thousand field theory simulations

Cited by 43 publications

References 35 publications

Approach to scaling in axion string networks

Approach to scaling in axion string networks

Beyond the Standard Models with cosmic strings

Loop decay in Abelian-Higgs string networks

Contact Info

Product

Resources

About