Axion fragmentation on the lattice

Morgante, Enrico; Ratzinger, Wolfram; Sato, Ryo; Stefanek, Ben A.

doi:10.1007/jhep12(2021)037

Cited by 14 publications

(18 citation statements)

References 67 publications

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“…As pointed out in previous literature [57][58][59], a finite ALP velocity may lead to the fragmentation of the pseudoscalar. This process allows for an energy transfer from the homogeneous zero mode to ALP excitations.…”

Section: A Alp Fragmentationmentioning

confidence: 72%

“…While the audible axion mechanism for GW production, in both, the conventional and kinetic misalignment scenario, relies on the presence of dark photons, GWs may also be sourced from excitations in the axion field itself due to the phenomenon of axion fragmentation [57][58][59]. We show that, indeed, GWs are hence generally produced in kinetic misalignment scenarios also in the absence of dark photons.…”

Section: Introductionmentioning

confidence: 79%

“…This is the most conservative choice, since in principle scalar modes, in contrast to vectors that we discussed in the main text, can be excited during inflation if they leave the horizon. Recent numerical studies have however shown that the exact initial condition has only a small effect on the efficiency of the fragmentation process [59].…”

Section: Main Results and Summarymentioning

confidence: 99%

“…Finally, let us note that there is in principle a more stringent bound for efficient growth than H GW < δk cr /a GW since the critical momentum and, therefore, the amplified modes are red-shifting, as well as due to growth time considerations, similar to the ones in the main text, that can be found in Refs. [57,59] but were skipped here for simplicity.…”

Section: A2 Analytic Considerationsmentioning

confidence: 99%

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Audible Axions with a Booster: Stochastic Gravitational Waves from Rotating ALPs

Madge,

Ratzinger,

Schmitt

et al. 2021

Preprint

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Gravitational waves provide a novel way to probe axions or axion-like particles coupled to a dark photon field, even in the absence of couplings to Standard Model particles. In the conventional misalignment mechanism, the generation of an observable stochastic gravitational wave background, however, requires large axion decay constants. We here investigate the gravitational wave signal generated within the kinetic misalignment scenario, where the axion is assumed to have a large initial velocity. Its kinetic energy then provides a sufficiently high energy budget to generate a detectable gravitational wave signal also at lower values of the decay constant. We obtain an analytic estimate as well as perform numerical simulations of the corresponding gravitational wave signal, and evaluate its detectability at current and future gravitational wave observatories. We further present the corresponding projected constraints on the parameter space of the model, along with the parameter regions in which the dark photon or axion constitute dark matter, or in which the baryon asymmetry of the Universe is generated via the axiogenesis mechanism. Finally, we compute the GW production from the fragmentation of rotating axions, which is however difficult to observe experimentally.

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Section: A Alp Fragmentationmentioning

confidence: 72%

Section: Introductionmentioning

confidence: 79%

Section: Main Results and Summarymentioning

confidence: 99%

Section: A2 Analytic Considerationsmentioning

confidence: 99%

See 2 more Smart Citations

Audible Axions with a Booster: Stochastic Gravitational Waves from Rotating ALPs

Madge,

Ratzinger,

Schmitt

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…It is found that the axion energy density in higher modes generated by the fragmentation is of the same order as the zero-mode component generated from Eq. (4.7) [76,139,140]. Hence we replace Eq.…”

Section: Axion Abundancementioning

confidence: 99%

Kination cosmology from scalar fields and gravitational-wave signatures

Gouttenoire¹,

Servant²,

Simakachorn³

2021

Preprint

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Kination denotes an era in the cosmological history corresponding to an equation of state ω = +1 such that the total energy density of the universe redshifts as the sixth inverse power of the scale factor. This arises if the universe is dominated by the kinetic energy of a scalar field. It has often been motivated in the literature as an era following inflation, taking place before the radiation era. In this paper, we review instead the possibility that kination is disconnected from primordial inflation and occurs much later, inside the Standard Model radiation era. We study the implications on all main sources of primordial gravitational waves. We show how this leads to very distinctive peaked spectra in the stochastic background of long-lasting cosmological sources of gravitational waves, namely the irreducible gravitational waves from inflation, and gravitational waves from cosmic strings, both local and global, with promising observational prospects. We present model-independent signatures and detectability predictions at LIGO, LISA, ET, CE, BBO, as a function of the energy scale and duration of the kination era. We then argue that such intermediate kination era is in fact symptomatic in a large class of axion models. We analyse in details the scalar field dynamics, the working conditions and constraints in the underlying models. We present the gravitational-wave predictions as a function of particle physics parameters. We derive the general relation between the gravitational-wave signal and the axion dark matter abundance as well as the baryon asymmetry. We investigate the predictions for the special case of the QCD axion. The key message is that gravitational-waves of primordial origin represent an alternative experimental probe of axion models.

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Lepto-axiogenesis and the scale of supersymmetry

Barnes

Harigaya

et al. 2023

J. High Energ. Phys.

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If the Peccei-Quinn field containing the QCD axion undergoes rotations in the early universe, the dimension-five operator responsible for neutrino masses can generate a lepton asymmetry that ultimately gives rise to the observed baryon asymmetry of the Universe. This lepto-axiogenesis scenario requires a flat potential for the radial direction of the Peccei-Quinn field, naturally realized in supersymmetric models. We carefully compute the efficiency of this mechanism for the Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) and Kim-Shifman-Vainshtein-Zakharov (KSVZ) axion models and place lower bounds on the masses of scalar superpartners required to reproduce the observed baryon asymmetry. For the KSVZ model, we find an efficiency for generation of the asymmetry six times larger than the previously extant computation after including scattering channels involving superpartners. In this case, the superpartner scale should be above 30 TeV for a domain wall number of one; the lower bound weakens for larger domain wall numbers. We find that the superpartner mass scale may also be as low as ~ 30 TeV for the DFSZ model. In all cases, the lower bound on the superpartner masses is inversely proportional to the sum of the squares of the neutrino masses and so can strengthen as the upper bound on the neutrino mass improves. We identify the parameter space where the axion rotation can simultaneously produce axion dark matter via kinetic misalignment; in this case it is possible to put an upper bound of order PeV on the masses of scalar superpartners.

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Axion fragmentation on the lattice

Cited by 14 publications

References 67 publications

Audible Axions with a Booster: Stochastic Gravitational Waves from Rotating ALPs

Audible Axions with a Booster: Stochastic Gravitational Waves from Rotating ALPs

Kination cosmology from scalar fields and gravitational-wave signatures

Lepto-axiogenesis and the scale of supersymmetry

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