Conveners
Inflation and early universe cosmology
- Sujeet Akula (Monash University)
Inflation and early universe cosmology
- Kazunori Kohri (KEK)
Inflation and early universe cosmology
- Archil Kobakhidze (The University of Sydney)
Inflation and early universe cosmology
- Andrew Fowlie (Monash University)
Inflation and early universe cosmology
- Geraint Lewis (The University of Sydney)
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Ms Malsawmtluangi Naulak (University of Hyderabad)28/11/2016, 16:10
We consider the Lorentz violating massive gravity for primordial gravitational waves and study the effects coming from the squeezed vacuum state on the subsequent B-mode polarization of the Cosmic Microwave Background. The resulting spectra oscillate on varying the mass of graviton and squeezing effect and are compared with the BICEP2/Keck Array at 150 GHz and Planck at 353 GHz collaboration data.
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Jisuke Kubo (Kanazawa University)28/11/2016, 16:30
We consider a model
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in which the electroweak scale
is non-perturbatively generated by
dynamical scale symmetry breaking
in a scalar QCD-like hidden sector.
We calculate
the energy spectrum of
cosmic gravitational wave background
which is produced by
the strong first-order scale phase transition
round O(TeV) in the early Universe. -
Adrian Manning (Sydney University)28/11/2016, 16:50
Gravitational wave radiation can be formed in the early universe from bubbles originating from first-order phase transitions. Depending on the characteristics of the phase transition, the generated gravitational waves may be detected by future space-based gravitational wave detectors. Typically these transitions occur at time scales when the temperature of the universe was of order 50 GeV or...
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Mitsuru Kakizaki (University of Toyama)28/11/2016, 17:10
Revealing dynamics of the electroweak phase transition is essential
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for probing new physics at the early Universe
such as electroweak baryogenesis,
which requires strongly first order phase transition.
We compute the spectrum of gravitational waves from
first order phase transition in models with additional
isospin singlet scalars with and without classical scale invariance,
and... -
Dr Rob Knoops (Chulalongkorn University, Bangkok)29/11/2016, 14:00
We present the results based on arXiv:1608.02121
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Dr Michal Artymowski (Jagiellonian University)29/11/2016, 14:20
In my talk I will present an idea of a scalar theory with a general potential $V(f(\varphi))$, where $f(\varphi) = \xi\sum_{k=1}^n \lambda_k \varphi^k$. I will show how to obtain generally flat inflationary potentials from such a model and prove that the Starobinsky inflation is one of the examples of $V(f)$ with a stationary point of an infinite order. I will generalise this model into a...
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Mr Ira Wolfson (Ben Gurion University of the Negev)29/11/2016, 14:40
I will first present in broad strokes the numerical package employed, and discuss regression tests to fully analytical cosmological models. I will then go on to present the [early work done][1] on the subject of small-scale 5th degree polynomial models, which were first suggested by [Ben-Dayan et al. in 2010][2]. These models successfully yield an inflationary scenario with a non-negligible...
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Dr Ryusuke Jinno (Institute for Basic Science (IBS))29/11/2016, 15:00
Particle production at the preheating era in inflation models with nonminimal coupling $ξ|φ|^2R$ and quartic potential $λ|φ|^4/4$ is discussed. We point out that the preheating proceeds much more violently than previously thought: if the inflaton is a complex scalar, the phase degree of freedom (global case) or the longitudinal gauge boson (gauged case) is violently produced at the first stage...
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Ippei Obata (Kyoto University)29/11/2016, 16:10
The inflationary universe predicts vacuum fluctuations of space-time, called primordial gravitational waves, whose spectra have slightly red-tilted and parity-symmetric features. This is an ordinary picture. Intriguingly, however, it is known that the axion-gauge coupling, motivated by string theory, could occur the particle production of gauge fields during inflation and provide the...
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Dr Andrew Fowlie (Monash University)29/11/2016, 16:30
The relaxion mechanism is a novel solution to the hierarchy problem that utilizes the dynamics of an axion-like field. I discuss results from the first statistical analysis of the relaxion mechanism ([arXiv:1602.03889][1]), in which we quantified the relative plausibility of a QCD and a non-QCD relaxion model versus the Standard Model with Bayesian statistics, which includes an automatic...
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Csaba Balazs (Monash University)29/11/2016, 16:50
A new gauge singlet scalar field can undergo a strongly
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first-order phase transition leading to gravitational waves observable
at aLIGO and stabilizes the electroweak vacuum at the same time. This
is because the sensitivity of aLIGO to cosmological phase transitions
at 10^7-10^8 GeV coincides with the requirement that the singlet scale
is close to the Standard Model instability scale.... -
Neil Barrie (The University of Sydney)29/11/2016, 17:10
We investigate the propagation of gravitational waves through the cosmic neutrino background, assuming it carries a non-zero lepton asymmetry. In this background, the graviton dispersion relation is found to exhibit birefringent behaviour leading to an enhancement/suppression of the gravitational wave amplitudes depending on the polarisation, where the magnitude of this effect is related to...
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Dario Gueter (Max Planck Institute for Physics)01/12/2016, 14:00
Heavy neutrinos with masses below the electroweak scale could simultaneously generate the light neutrino masses via the seesaw mechanism and the baryon asymmetry of the universe via leptogenesis. The requirement to explain both imposes constraints on the mass spectrum of the heavy neutrinos, their flavour mixing pattern and $CP$ properties. If any heavy neutral leptons are discovered in the...
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Graham White (Monash University)01/12/2016, 14:20
The NMSSM has the attractive features of being able to provide at least a partial solution to the little hierarchy problem through the introduction of a guage singlet. Its usefulness in electroweak baryogenesis is more pronounced - with the singlet being useful to catalyze a boost in the strength of the EWPT without conflicting with collider constraints. Furthermore, interactions between the...
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Tommi Tenkanen01/12/2016, 14:40
We study a singlet scalar extension of the Standard Model. The singlet scalar is coupled non-minimally to gravity and assumed to drive inflation, and also couple sufficiently strongly with the SM Higgs field in order to provide for a strong first order electroweak phase transition. Requiring the model to describe inflation successfully, be compatible with the LHC data, and yield a strong first...
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Dr Sujeet Akula (Monash University)01/12/2016, 15:00
We present semi-analytic techniques for finding bubble wall profiles during a first order phase transitions with multiple scalar fields. Our method involves reducing the system to a single-field problem, and then creating a convergent series of perturbative corrections to an analytic ansatz solution.
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Suntharan Arunasalam (University of Sydney)01/12/2016, 15:20
Electroweak monopoles are spherically symmetric configurations of the gauge fields that derive their stability from their topological nature. This talk discusses the effect of regularised Cho-Maison monopoles on the strength of the electroweak phase transition and the implications of this on electroweak baryogenesis.
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Wanil Park01/12/2016, 16:10
It will be shown that, even if Big Bang Nucleosynthesis constrains the asymmetry of electron neutrinos to be of or less than $\mathcal{O}(10^{-3})$, asymmetries of muon- and tau-neutrinos can be large and lead to $\Delta N_{\rm eff}=\mathcal{O}(0.1-1)$ as the number of extra neutrino species. Also, it will be shown that $\Delta N_{\rm eff}$ should be estimated from contributions of neutrino...
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Naoyuki Takeda01/12/2016, 16:30
Scalar fields are know to have various roles in the early Universe such as inflaton. Among of them, some real scalar fields are known to fragment into spatially localized and long-lived solitons called oscillons or I-balls. We prove the adiabatic invariance of the oscillons/I-balls for a potential that allows periodic motion even in the presence of non-negligible spatial gradient energy. We...
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Dr Toyokazu Sekiguchi (IBS/CTPU)01/12/2016, 16:50
Predicted by the Peccei-Quinn (PQ) mechanism, that solves the Strong CP problem in QCD, axion is one of the most promising candidates of dark matter. In my talk, I will be reviewing recent developments in estimation of the abundance of axion CDM from topological defects. When the reheating temperature is higher than the PQ energy scale, the symmetry breaking of U(1)_{PQ} takes place in the...
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Shelley Liang (The university of Sydney)01/12/2016, 17:10
We propose a new class of natural inflation models based on a hidden scale invariance. In a very generic Wilsonian effective field theory with an arbitrary number of scalar fields, which exhibits scale invariance via the dilaton, the potential necessarily contains a flat direction in the classical limit. This flat direction is lifted by small quantum corrections and inflation is realised...
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