Self-unitarization of New Higgs Inflation and compatibility with Planck and BICEP2 data

Germani, Cristiano; Watanabe, Yuki; Wintergerst, Nico

doi:10.1088/1475-7516/2014/12/009

Cited by 48 publications

(62 citation statements)

References 70 publications

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“…The theory (10), seems to lose tree-level perturbative unitarity when the potential reaches the transition value Λ 4 t [11]. However, perturbative unitarity is actually not lost.…”

Section: Higgs-gravity Systemmentioning

confidence: 99%

“…However, perturbative unitarity is actually not lost. Indeed, at the same scale a non-negligible gravitational background is generated, leading to a kinetic mixing between the graviton and the Higgs boson [11]. Upon diagonalization of the Higgs-graviton system, one discovers that the unitarity violation scale is actually background dependent.…”

Section: Higgs-gravity Systemmentioning

confidence: 99%

“…If instead the Higgs boson is kinetically coupled to curvature, as in the "new Higgs inflation" of [10], no new degrees of freedom are necessary in the inflationary regime [11]. In this paper we will consider an extension of such scenario and analyze the effect of quantum corrections.…”

Section: Introductionmentioning

confidence: 99%

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Electroweak vacuum stability and inflation via nonminimal derivative couplings to gravity

Vita

Germani

2016

Phys. Rev. D

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We show that the Standard Model vacuum can be stabilized if all particle propagators are nonminimally coupled to gravity. This is due to a Higgs-background dependent redefinition of the Standard Model fields: in terms of canonical variables and in the large Higgs field limit, the quantum fluctuations of the redefined fields are suppressed by the Higgs background. Thus, in this regime, quantum corrections to the tree-level electroweak potential are negligible. Finally, we show that in this framework the Higgs boson can be responsible for inflation. Due to a numerical coincidence that originates from the CMB data, inflation can happen if the Higgs boson mass, the top mass, and the QCD coupling lie in a region of the parameter space approximately equivalent than the one allowing for electroweak vacuum stability in the Standard Model. We find some (small) regions in the Standard Model parameter space in which the new interaction "rescues" the electroweak vacuum, which would not be stable in the Standard Model.

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“…The theory (10), seems to lose tree-level perturbative unitarity when the potential reaches the transition value Λ 4 t [11]. However, perturbative unitarity is actually not lost.…”

Section: Higgs-gravity Systemmentioning

confidence: 99%

Section: Higgs-gravity Systemmentioning

confidence: 99%

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Electroweak vacuum stability and inflation via nonminimal derivative couplings to gravity

Vita

Germani

2016

Phys. Rev. D

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“…For illustrative purposes, we will fix N = 60. Once I is given, all parameters of the system are only tight to the value of the amplitude of scalar perturbations [22] …”

Section: Numerics: the Case Of New Higgs Inflationmentioning

confidence: 99%

On post-inflation validity of perturbation theory in Horndeski scalar-tensor models

Germani¹,

Kudryashova²,

Watanabe³

2016

J. Cosmol. Astropart. Phys.

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Abstract. By using the newtonian gauge, we re-confirm that, as in the minimal case, the re-scaled Mukhanov-Sasaki variable is conserved leading to a constraint equation for the Newtonian potential. However, conversely to the minimal case, in Horndeski theories, the super-horizon Newtonian potential can potentially grow to very large values after inflation exit. If that happens, inflationary predictability is lost during the oscillating period. When this does not happen, the perturbations generated during inflation can be standardly related to the CMB, if the theory chosen is minimal at low energies. As a concrete example, we analytically and numerically discuss the new Higgs inflationary case. There, the Inflaton is the Higgs boson that is non-minimally kinetically coupled to gravity. During the highenergy part of the post-inflationary oscillations, the system is anisotropic and the Newtonian potential is largely amplified. Thanks to the smallness of today's amplitude of curvature perturbations, however, the system stays in the linear regime, so that inflationary predictions are not lost. At low energies, when the system relaxes to the minimal case, the anisotropies disappear and the Newtonian potential converges to a constant value. We show that the constant value to which the Newtonian potential converges is related to the frozen part of curvature perturbations during inflation, precisely like in the minimal case.

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“…For example, see [37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52]. We believe that it is still too early to say which model is correct.…”

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confidence: 99%

Constraint on inflation model from BICEP2 and WMAP 9-year data

Cheng

Huang

2015

Int. J. Mod. Phys. D

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Even though Planck data released in 2013 (P13) is not compatible with Background Imaging of Cosmic Extragalactic Polarization (B2) and some local cosmological observations, including Supernova Legacy Survey (SNLS) samples and H0 prior from Hubble Space Telescope (HST) etc, Wilkinson Microwaves Anisotropy Probe 9-year data (W9) is consistent with all of them in the base six-parameter ΛCDM+tensor cosmology quite well. In this letter, we adopt the combinations of B2+W9 and B2+W9+SNLS+BAO+HST to constrain the cosmological parameters in the base six-parameter ΛCDM+tensor model with nt = −r/8, where r and nt are the tensor-to-scalar ratio and the tilt of relic gravitational wave spectrum, and BAO denotes Baryon Acoustic Oscillation. We find that the Harrison-Zel'dovich (HZ) scale invariant scalar power spectrum is consistent with both data combinations, chaotic inflation is marginally disfavored by the data at around 2σ level, but the power-law inflation model and the inflation model with inverse power-law potential can fit the data nicely.PACS numbers: 98.70. Vc,98.80.Cq, More than thirty years ago inflation [1][2][3] was proposed to solve the puzzles, such as the flatness problem, horizon problem, monopole problem and so on, in the hot big bang model. In fact, the spatial flatness can be taken as a prediction of inflation model which has been confirmed by Wilkinson Microwaves Anisotropy Probe 9-year data (W9) [4] and Planck data released in 2013 (P13) [5]. On the other hand, the quantum fluctuations generated during inflation [6][7][8][9][10][11] can seed the anisotropies in the cosmic microwaves background (CMB) radiation and the formation of large-scale structure. Since the Hubble parameter during inflation is roughly a constant, the spectrum of scalar perturbations is nearly scale-invariant. An adiabatic, Gaussian and nearly scale-independent scalar power spectrum has also been confirmed by W9 and P13. In addition, the quantization of the gravitational field during inflation produces a primordial background of stochastic gravitational waves [12][13][14][15][16]. In the last decades, many group tried their best to hunt for the signal of relic gravitational waves.Recently discovery of relic gravitational waves was reported by Background Imaging of Cosmic Extragalactic Polarization (B2) [17], and the tensor-to-scalar ratio is given by r = 0.20with r = 0 disfavored at 7.0σ. It is certainly a breakthrough of basic science in these years. Before B2 claimed its discovery, some hints of relic gravitational waves around r ∼ 0.2 were illustrated in [18,19] 2 ), angular scale of the sound horizon at last-scattering (θ MC ), optical depth (τ ), scalar spectrum power-law index (n s ) and log power of the primordial curvature perturbations (ln(10 10 A s )). Including the perturbations of primordial gravitational waves, the six-parameter ΛCDM model is extended to be ΛCDM+tensor model. However, combining with WMAP Polarization data [4], ACT [21] and SPT [22], P13 [5] imply a much smaller tensor-to-scalar ratio, compared to tha...

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Self-unitarization of New Higgs Inflation and compatibility with Planck and BICEP2 data

Cited by 48 publications

References 70 publications

Electroweak vacuum stability and inflation via nonminimal derivative couplings to gravity

Electroweak vacuum stability and inflation via nonminimal derivative couplings to gravity

On post-inflation validity of perturbation theory in Horndeski scalar-tensor models

Constraint on inflation model from BICEP2 and WMAP 9-year data

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