Global cosmic string networks as a function of tension

Klaer, Vincent B.

doi:10.1088/1475-7516/2020/06/021

Cited by 36 publications

(47 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A similar linear-log increase has been seen in independent studies of global strings in[22][23][24][25][26][27].…”

supporting

confidence: 81%

“…[7] (see also refs. [22][23][24][25][26][27] for further supporting evidence), increasing logarithmically with time.…”

Section: String Densitymentioning

confidence: 74%

“…These include refs. [23,27], which partially reproduce the possible effects of an enhanced string tension and find ξ 5; Nambu-Goto simulations, which seem to prefer values between 10 and 20 [18,19,28]; and recent local string simulations, which give ξ loc = 4(1) [23,29]. Since the final abundance approximately scales as ξ 1/2 , even assuming that the growth of ξ saturates at the smaller values ξ 4 ÷ 5, this would affect the final bound by less than a factor of 2, within our target precision.…”

Section: Results and Phenomenological Implicationsmentioning

confidence: 99%

“…An enhanced value of ξ was also observed in global string networks in refs. [23,27] where a large value of the effective string tension was achieved by means of a clever modification of the physics at the string core m r .…”

Section: String Densitymentioning

confidence: 99%

“…The continuum extrapolation indicates that, at least for fat strings, 〈γ〉 seems to asymptotically approach a constant mildly relativistic value 〈γ〉 = 1.3 ÷ 1.4. 27 More detailed information about string velocities can be inferred from the γ-factor distribution function. We define ξ γ to be the portion of ξ with boost factor smaller than γ.…”

Section: B2 String Velocitiesmentioning

confidence: 99%

See 4 more Smart Citations

More axions from strings

2021

View full text Add to dashboard Cite

We study the contribution to the QCD axion dark matter abundance that is produced by string defects during the so-called scaling regime. Clear evidence of scaling violations is found, the most conservative extrapolation of which strongly suggests a large number of axions from strings. In this regime, nonlinearities at around the QCD scale are shown to play an important role in determining the final abundance. The overall result is a lower bound on the QCD axion mass in the post-inflationary scenario that is substantially stronger than the naive one from misalignment.

show abstract

“…A similar linear-log increase has been seen in independent studies of global strings in[22][23][24][25][26][27].…”

supporting

confidence: 81%

“…[7] (see also refs. [22][23][24][25][26][27] for further supporting evidence), increasing logarithmically with time.…”

Section: String Densitymentioning

confidence: 74%

Section: Results and Phenomenological Implicationsmentioning

confidence: 99%

Section: String Densitymentioning

confidence: 99%

Section: B2 String Velocitiesmentioning

confidence: 99%

See 3 more Smart Citations

More axions from strings

2021

View full text Add to dashboard Cite

show abstract

Diraxiogenesis

Berbig

2024

J. High Energ. Phys.

View full text Add to dashboard Cite

The family of Dirac Seesaw models offers an intriguing alternative explanation for the smallness of neutrino masses without necessarily requiring microscopic lepton number violation, when compared to the more familiar class of Majorana Seesaws. A global U(1)D symmetry, that is explicitly broken by a higher dimensional scalar operator, ensures that the right handed neutrino does not couple directly to the Standard Model like Higgs and an exact gauged or residual lepton number symmetry prohibits all Majorana masses. We demonstrate that all three Dirac Seesaws possess a Pseudo-Nambu-Goldstone boson associated with the U(1)D symmetry, that we call the Diraxion, whose cosmological dynamics have so far been left unexplored. Furthermore we illustrate that a Dirac-Leptogenesis version of the recently proposed Lepto-Axiogenesis scenario can be realized in this class of models, leading to a unified origin of the observed baryon asymmetry and dark matter relic abundance. Explaining only the baryon asymmetry can lead to potentially observable amounts of right handed neutrino dark radiation with ∆Neff. ≲ 0.028. On the other hand, if we only fix the dark matter abundance via the kinetic misalignment mechanism, this set-up could lead to detectable signatures in proposed cosmic neutrino background experiments via decays of eV-scale Diraxions to neutrinos. Here there is no domain wall problem, since topological defects decay to a subleading fraction of relic Diraxions. A key ingredient of all Axiogenesis scenarios is the dynamics of relatively light scalar called the Saxion, that in our case has a mass at the GeV-scale and which might reveal itself in heavy meson decays or collider searches. Our setup predicts isocurvature perturbations in baryons, dark matter and dark radiation sourced by fluctuations of the Saxion.

show abstract

Early vs late string networks from a minimal QCD Axion

Gorghetto,

Hardy,

Nicolaescu

et al. 2024

J. High Energ. Phys.

View full text Add to dashboard Cite

We propose a new regime of minimal QCD axion dark matter that lies between the pre- and post-inflationary scenarios, such that the Peccei-Quinn (PQ) symmetry is restored only on sufficiently large spatial scales. This leads to a novel cosmological evolution, in which strings and domain walls re-enter the horizon and annihilate later than in the ordinary post-inflationary regime, possibly even after the QCD crossover. Such dynamics can occur if the PQ symmetry is restored by inflationary fluctuations, i.e. the Hubble parameter during inflation HI is larger than the PQ breaking scale fa, but it is not thermally restored afterwards. Solving the Fokker-Planck equation, we estimate the number of inflationary e-folds required for the PQ symmetry to be, on average, restored. Moreover, we show that, in the large parts of parameter space where the radial mode is displaced from the minimum by de Sitter fluctuations, a string network forms due to the radial mode oscillating over the top of its potential after inflation. In both cases we identify order one ranges in HI/fa and in the quartic coupling λ of the PQ potential that lead to the late-string dynamics. In this regime the cosmological dark matter abundance can be reproduced for axion decay constants as low as the astrophysical constraint 𝒪(108) GeV, corresponding to axion masses up to 10−2 eV, and with miniclusters with masses as large as 𝒪(10)M⊙.

show abstract

Global cosmic string networks as a function of tension

Cited by 36 publications

References 53 publications

More axions from strings

More axions from strings

Diraxiogenesis

Early vs late string networks from a minimal QCD Axion

Contact Info

Product

Resources

About