Gauge fields and inflation: Chiral gravitational waves, fluctuations, and the Lyth bound

Adshead, Peter; Martinec, Emil J.; Wyman, Mark

doi:10.1103/physrevd.88.021302

Cited by 167 publications

(237 citation statements)

References 11 publications

(19 reference statements)

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“…To complete our leptogenesis model, now we need to determine net lepton and photons number densities predicted by these models. , H 10 −6 and γ = 9 (which has highly chiral gravitational waves in this γ) [17,23]. The analytical approximation and numerical solution perfectly overlaid each other on sub-horizon scalesτ 5, while as getting closer to the horizon crossing pointτ = 1, they eventually start to deviate from each other.…”

Section: Confronting With the Observationmentioning

confidence: 74%

“…That leads to rightand left-handed super-horizon power spectrums which are different from the standard prediction of scalar inflationary models [17,23].…”

Section: Confronting With the Observationmentioning

confidence: 78%

“…As getting closer to the horizon crossing pointτ = 1, analytical and numerical solutions eventually start to deviate from each other. It is noteworthy to mention that the system which is presented here (with γ = 9) leads to highly chiral tensor modes [17,23]. Let us quantify the enlargement of chirality in the system by Θ ≡…”

Section: Tensor Perturbationsmentioning

confidence: 99%

“…Here, the gauge field slows down the inflaton's evolution and leads to slow-roll inflation even with the natural values of f (f M P l ). Although a natural and well motivated inflationary model at the background level, the chromo-natural model is disfavored by the resent Planck data [23]- [25].…”

Section: Two Inflationary Models Involving Non-abelian Gauge Fieldsmentioning

confidence: 99%

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Chiral gravity waves and leptogenesis in inflationary models with non-Abelian gauge fields

Maleknejad

2014

Phys. Rev. D

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We present a leptogenesis scenario associated with inflationary models involving non-Abelian gauge fields within the standard model of particle physics (SM). We show that this class of inflationary models generates intrinsic birefringent gravitational waves that following [8], through the gravitational chiral anomaly in SM, can naturally create a net lepton number density. The CP violating interaction is produced by tensor fluctuations of the gauge field, while the efficiency of this process is determined by the effective background value of the gauge field. We demonstrate that this mechanism can create the observed value of baryon to photon number density in a natural range of parameters of these models.

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Section: Confronting With the Observationmentioning

confidence: 74%

“…That leads to rightand left-handed super-horizon power spectrums which are different from the standard prediction of scalar inflationary models [17,23].…”

Section: Confronting With the Observationmentioning

confidence: 78%

Section: Tensor Perturbationsmentioning

confidence: 99%

Section: Two Inflationary Models Involving Non-abelian Gauge Fieldsmentioning

confidence: 99%

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Chiral gravity waves and leptogenesis in inflationary models with non-Abelian gauge fields

Maleknejad

2014

Phys. Rev. D

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“…We consider weak distortions of the spacetime metric and the gauge field, δg µν = a 2 h µν and δ A µ · e ν = ay µν , where h µν , y µν are transverse, traceless, and synchronous. Since the Yang-Mills coupling breaks the chiral symmetry of left-and right-circular polarizations [17], it is practical to express the gravitational and gauge field waves with amplitudes h p , y pn in a chiral basis with p = L, R for n = 1, 2, ... , N. A further change of variables, h = H √ 2/aM P and y = Y / √ 2a, puts the action into canonical form. The Lagrangian for gravitational and gauge field waves, propagating with Fourier wave number k much greater than both the expansion rate and the gauge field time rate of change, is given by…”

mentioning

confidence: 99%

Gravitational wave–Gauge field oscillations

2016

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Gravitational waves propagating through a stationary gauge field transform into gauge field waves and back again. When multiple families of flavor-space locked gauge fields are present, the gravitational and gauge field waves exhibit novel dynamics. At high frequencies, the system behaves like coupled oscillators in which the gravitational wave is the central pacemaker. Due to energy conservation and exchange among the oscillators, the wave amplitudes lie on a multidimensional sphere, reminiscent of neutrino flavor oscillations. This phenomenon has implications for cosmological scenarios based on flavor-space locked gauge fields.In a remarkable series of papers starting with the work of Gertsenshteyn [1], the authors showed that a gravitational wave propagating through a stationary magnetic field converts into an electromagnetic wave and back again [2][3][4]. Now that gravitational waves have been directly detected [5], no doubt there will be searches for this effect [6].Here we consider the more general phenomenon of the conversion of a gravitational wave into a stationary gauge field, as may be present in the early stages of the Universe [7][8][9]. In particular, we show that gravitational waves transform into tensor waves of a gauge field, disappearing and reappearing much like neutrino flavor oscillations. More complicated oscillation patterns are possible for multiple families of gauge fields. Quantization of these gravitational and gauge field tensor modes reveals a novel relationship between the energy and flavor eigenstates that may leave an imprint on a spectrum of primordial gravitational waves, or even suggest a new mechanism for the origin of a primordial spectrum.We consider a gauge field under general relativity,with metric signature − + ++, M P is the reduced Planck mass, and L m represents any other fields that may be present. We take an SU(2) fieldwhere g Y is the Yang-Mills coupling and the vector notation indicates direction in the three-dimensional flavor space. It is essential for this effect that the gauge field have a vacuum expectation value (vev), the analog of a stationary electric or magnetic field. To match the symmetries of our cosmological spacetime, we build a homogeneous and isotropic configuration as recently considered in the context of cosmic acceleration for inflation [7][8][9] or dark energy [10][11][12]. We work in the timelike gauge, so that A t = 0, and require that the remaining components, one per each group generator, be spatially independent in order to ensure homogeneity. Isotropy is then achieved by identifying the global symmetry of SU(2) with the rotational O(3) symmetry of Euclidean space. Hence, we write A µ = φ(τ ) e µ where e µ is a set of three mutually orthogonal, spacelike basis vectors. That is, the vector fields for flavors 1, 2, 3 point along the x, y, z directions, and we call this configuration flavorspace locked. The equation of motion in an expanding spacetime with line element ds, which may be solved exactly in terms of elliptic Jacobi functions. The...

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The inflated Chern-Simons number in spectator chromo-natural inflation

Bagherian

Reece

2023

J. High Energ. Phys.

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The chromo-natural inflation (CNI) scenario predicts a potentially detectable chiral gravitational wave signal, generated by a Chern-Simons coupling between a rolling scalar axion field and an SU(2) gauge field with an isotropy-preserving classical background during inflation. However, the generation of this signal requires a very large integer Chern-Simons level, which can be challenging to explain or embed in a UV-complete model. We show that this challenge persists in the phenomenologically viable spectator field CNI (S-CNI) model. Furthermore, we show that a clockwork scenario giving rise to a large integer as a product of small integers can never produce a Chern-Simons level large enough to have successful S-CNI phenomenology. We briefly discuss other constraints on the model, both in effective field theory based on partial-wave unitarity bounds and in quantum gravity based on the Weak Gravity Conjecture, which may be relevant for further explorations of alternative UV completions.

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Gauge fields and inflation: Chiral gravitational waves, fluctuations, and the Lyth bound

Cited by 167 publications

References 11 publications

Chiral gravity waves and leptogenesis in inflationary models with non-Abelian gauge fields

Chiral gravity waves and leptogenesis in inflationary models with non-Abelian gauge fields

Gravitational wave–Gauge field oscillations

The inflated Chern-Simons number in spectator chromo-natural inflation

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