α-attractors: Planck, LHC and dark energy

Homogeneous oscillations of the inflaton after inflation can be unstable to small spatial perturbations even without coupling to other fields. We show that for inflaton potentials ∝ jϕj 2n near jϕj ¼ 0 and flatter beyond some jϕj ¼ M, the inflaton condensate oscillations can lead to self-resonance, followed by its complete fragmentation. We find that for nonquadratic minima (n > 1), shortly after backreaction, the equation of state parameter, w → 1=3. If M ≪ m Pl , radiation domination is established within less than an e-fold of expansion after the end of inflation. In this case self-resonance is efficient and the condensate fragments into transient, localised spherical objects which are unstable and decay, leaving behind them a virialized field with mean kinetic and gradient energies much greater than the potential energy. This end-state yields w ¼ 1=3. When M ∼ m Pl we observe slow and steady, self-resonance that can last many e-folds before backreaction eventually shuts it off, followed by fragmentation and w → 1=3. We provide analytical estimates for the duration to w → 1=3 after inflation, which can be used as an upper bound (under certain assumptions) on the duration of the transition between the inflationary and the radiation dominated states of expansion. This upper bound can reduce uncertainties in CMB observables such as the spectral tilt n s , and the tensor-to-scalar ratio r. For quadratic minima (n ¼ 1), w → 0 regardless of the value of M. This is because when M ≪ m Pl , long-lived oscillons form within an e-fold after inflation, and collectively behave as pressureless dust thereafter. For M ∼ m Pl , the self-resonance is inefficient and the condensate remains intact (ignoring longterm gravitational clustering) and keeps oscillating about the quadratic minimum, again implying w ¼ 0.

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“…3 The mass scale in Eqs. (2), (3) is related to the conventional α-parameter [43,[47][48][49][50][51][52][53][54][55][56][57] …”

Section: Modelsmentioning

confidence: 99%

Self-resonance after inflation: Oscillons, transients, and radiation domination

2018

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“…Another instance of a non-flat geometry of the S-field are the 'axion stabiliser' terms [38,39] in the Kähler potential metric of the kind…”

Section: Jhep07(2017)057mentioning

confidence: 99%

D 3 ¯ $$ \overline{D3} $$ induced geometric inflation

Каллош

Linde

Roest

et al. 2017

J. High Energ. Phys.

Self Cite

126

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Effective supergravity inflationary models induced by anti-D3 brane interaction with the moduli fields in the bulk geometry have a geometric description. The Kähler function carries the complete geometric information on the theory. The non-vanishing bisectional curvature plays an important role in the construction. The new geometric formalism, with the nilpotent superfield representing the anti-D3 brane, allows a powerful generalization of the existing inflationary models based on supergravity. They can easily incorporate arbitrary values of the Hubble parameter, cosmological constant and gravitino mass. We illustrate it by providing generalized versions of polynomial chaotic inflation, Tand E-models of α-attractor type, disk merger. We also describe a multi-stage cosmological attractor regime, which we call cascade inflation.

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“…For the above plot we have focussed on the α-attractor models [17][18][19], but it can be easily generalized to models with different potentials during the inflationary phase.…”

mentioning

confidence: 99%

Equation of State and Duration to Radiation Domination after Inflation

2017

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We calculate the equation of state after inflation and provide an upper bound on the duration before radiation domination by taking the nonlinear dynamics of the fragmented inflaton field into account. A broad class of single-field inflationary models with observationally consistent flattening of the potential at a scale M away from the origin, V (φ) ∝ |φ| 2n near the origin, and where the couplings to other fields are ignored are included in our analysis. We find that the equation of state parameter w → 0 for n = 1 and w → 1/3 (after sufficient time) for n 1. We calculate how the number of e-folds to radiation domination depends on both n and M when M ∼ mPl, whereas when M mPl, we find that the duration to radiation domination is negligible. Our results are explained in terms of a linear instability analysis in an expanding universe, scaling arguments, and are supported by 3+1 dimensional lattice simulations. We show how our work significantly reduces the uncertainty in inflationary observables, even after including couplings to additional light fields.Introduction -Inflationary cosmology provides a consistent framework for calculating the initial conditions responsible for the observed temperature fluctuations in the cosmic microwave background [1]. However, there is a gap in our understanding of how inflation ends and ultimately leads to a radiation-dominated, thermal universe before the production of light elements. The poorly constrained post-inflationary equation of state of the universe and the duration before radiation domination influence the interpretation of inflationary observables and the reheating temperature [2-11]; they affect predictions for baryogenesis and primordial relics [12][13][14].

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α-attractors: Planck, LHC and dark energy

Cited by 143 publications

References 63 publications

Self-resonance after inflation: Oscillons, transients, and radiation domination

Self-resonance after inflation: Oscillons, transients, and radiation domination

D 3 ¯ $$ \overline{D3} $$ induced geometric inflation

Equation of State and Duration to Radiation Domination after Inflation

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