Conveners
Inflation and phase transitions: Inflation + PT
- Kari Enqvist
Inflation and phase transitions: Inflation + PT
- Kari Enqvist
Inflation and phase transitions: Inflation
- Kari Enqvist
Inflation and phase transitions: PT
- Mark Hindmarsh
Inflation and phase transitions: PT
- Mark Hindmarsh
Inflation and phase transitions: Inflation
- Kari Enqvist
Inflation and phase transitions: Inflation + PT
- Arttu Rajantie
Inflation and phase transitions: Inflation + PT
- Arttu Rajantie
Inflation and phase transitions: Inflation
- Marek Demiański
Inflation and phase transitions: PT
- Mariusz Dąbrowski
Antonio Racioppi
(NICPB, Estonia)
08/09/2015, 14:00
Theories where the Planck scale is dynamically generated from dimensionless interactions provide predictive inflationary potentials and super-Planckian field variations. We first study the minimal single-field realisation in the low-energy effective field theory limit, finding the predictions $n_s \approx 0.96$ for the spectral index and $r \approx 0.13$ for the tensor-to-scalar ratio, which...
Djuna Croon
(University of Sussex, United Kingdom)
08/09/2015, 14:20
I will discuss the appeal of pseudo-Goldstone bosons (pGBs) for the generation of scales in Early Universe cosmology. In particular, I will demonstrate how a pGB inflaton can solve the hierarchy problem of inflation (the tension between the Lyth bound and the inflationary scale as preferred by CMB anisotropies), while avoiding the problems with trans-Planckian scales that are typically...
Kiwoon Choi
(KAIST, Republic of Korea)
08/09/2015, 14:40
We study the primordial scalar and tensor perturbations in inflation scenario involving a spectator dilaton in addition to the conventional inflaton field. In our setup, the rolling dilaton causes a tachyonic instability of gauge fields, leading to a copious production of gauge fields in the superhorizon regime, which generates additional scalar and tensor perturbations through gravitational...
Will Kinney
(SUNY Buffalo, United States)
08/09/2015, 15:00
Recent data from the Cosmic Microwave Background and Large-Scale structure confirm the basic predictions of inflation in the early universe: a Gaussian, adiabatic spectrum of density perturbations with correlations on super-Hubble length scales. Furthermore, the density perturbations are known to be nearly (but not exactly) scale-invariant over a factor of at least a thousand in wavelength. I...
Emanuela Dimastrogiovanni
(ASU, United States)
08/09/2015, 15:20
In some early universe scenarios, a correlation between a long-wavelength tensor perturbation with two short wavelength scalar-fluctuations may generate an observable signal in form of a quadrupolar power asymmetry. Alternatively, it may produce an off-diagonal contribution to the matter power spectrum which would represent a possible probe for primordial gravitational waves. We discuss how...
Jason Tsz Shing Yue
(University of Sydney, Australia)
08/09/2015, 16:10
Given the limited precision on the measurement of the Higgs self-coupling and the top Yukawa coupling, we explore the possibility for anomalous Higgs couplings within the nonlinear realisation of the electroweak symmetry, together with a CP-violating top-Higgs sector. In such a scenario, the electroweak phase transition may be strongly first order and the additional sources of CP-violation may...
Vincent Vennin
(ICG, University of Portsmouth, United Kingdom)
08/09/2015, 16:30
In stochastic inflation, the quantum effects on the dynamics of the long wavelength perturbations are modelled by a stochastic noise. To study quantum corrections to inflationary observables, one thus needs to extract correlation functions of cosmological perturbations from this formalism. I will show how this can be done in practice, for all order correlation functions, in a non perturbative...
Konstantinos DIMOPOULOS
(Lancaster University, United Kingdom)
08/09/2015, 16:50
A new family of inflation models is introduced and studied. The models are characterised by a scalar potential which, far from the origin, approximates an inflationary plateau, while near the origin becomes monomial, as in chaotic inflation. The models can be obtained in the context of global supersymmetry starting with a superpotential, which interpolates from a generalised monomial to an...
Zachary Kenton
(Queen Mary University of London, United Kingdom)
08/09/2015, 17:10
Soft limits of correlation functions of the primordial curvature perturbation provide a unique opportunity to confront theoretically clean results against observations of non-Gaussianity. In this work we calculate the squeezed limit of the bispectrum of the curvature perturbation produced by multifield inflation, which allows for a very large hierarchy of scales. This is achieved by taking...
Manuel Krämer
(Institute of Physics, University of Szczecin, Poland)
08/09/2015, 17:30
We calculate corrections originating from canonical quantum gravity to the power spectra of gauge-invariant scalar and tensor perturbations during inflation. This is done by performing a semiclassical Born–Oppenheimer type of approximation to the Wheeler–DeWitt equation, from which we obtain a Schrödinger equation with a quantum-gravitational correction term. We perform our calculation both...
Nelson Videla
(Universidad de Chile, Chile)
08/09/2015, 17:50
In the present work we study the possibility that a higher dimensional scenario, in particular the RS II
brane-world model, can describe the dynamics of the Universe in its very early epochs. We propose this possibility
in the context of warm inflation scenario, for a Universe evolving according to
the intermediate scale factor, and how a generalized form of the dissipative coefficient...
Naoya Kitajima
(Tohoku University, Japan)
09/09/2015, 09:00
We point out that domain wall formation is a more common phenomenon in the Axiverse
than previously thought. Level crossing could take place if there is a mixing between axions,
and if some of the axions acquire a non-zero mass through non-perturbative effects as
the corresponding gauge interactions become strong. The axion potential
changes significantly during the level crossing, which...
Tomo Takahashi
(Saga University, Japan)
09/09/2015, 09:00
We consider a model where primordial density fluctuations are generated both from the inflaton and the spectator field such as the curvaton. In general, the power spectra generated from different scalar fields exhibit a different scale dependence, thus it is possible that fluctuations sourced by one field dominates on large scales, while those from the other field can give a significant...
Asier Lopez-Eiguren
(University of the Basque Country, Spain)
09/09/2015, 09:20
Our ongoing calibration of the analytical models for Semilocal strings using field theory simulations indicate that the velocities of the string ends will be of great significance. It is known that Semilocal string ends behave as global monopoles, so we are developing a technique to measure global monopole velocities using field theory simulations. In this presentation, we will explain the...
Tomohiro Matsuda
(Saitama Institute of Technology, Japan)
09/09/2015, 09:20
When the Higgs field starts oscillation after Higgs inflation, gauge bosons will be produced non-perturbatively near the Enhanced Symmetry Point (ESP). Just after the particle production, when the Higgs field is going away from the ESP, gauge bosons gain mass and decay or annihilate into Standard Model (SM) fermions. In that way, left-handed neutrinos can be generated from the heavy...
Gerasimos Rigopoulos
(Newcastle University, United Kingdom)
09/09/2015, 09:40
We show how the full quantum description of a scalar field with quartic self-interaction in de Sitter spacetime is equivalent to Brownian motion of a particle in a medium of de Sitter temperature T_DS = H/2π on large wavelengths. We then argue that the system exhibits a fluctuation-dissipation relation and its equilibrium distribution is Maxwell-Boltzmann, implying kinetic and potential...
Adam Christopherson
(University of Florida, United States)
09/09/2015, 09:40
In this talk, I will present recent work focusing on a model of inflation embedded in a scalar-tensor theory. This model contains two fields, one that drives inflation, and a second that stabilizes the Planck mass (or the gravitational constant) in the early universe. In this model, the stabilization occurs a few efolds after inflation. We show, by performing a numerical calculation, that the...
Takahiro TERADA
(The University of Tokyo, Japan)
09/09/2015, 10:00
Supergravity is a well-motivated framework to study inflation. Recently (large field) inflation in supergravity with a single inflaton superfield (thus without the stabilizer field) obtained interests and was developed. Two major approaches are those of (1) Ketov and Terada (2014), and (2) Roest and Scalisi (2015), and also Linde (2015). We study consequences of combining these models of...
David Edwards
(Institute for Astronomy, University of Edinburgh, United Kingdom)
09/09/2015, 10:00
Recently, there has been a large amount of work considering theories of inflation which lead to a common observational prediction - the Universal Attractors.
I will present the attractor structure in the case of the strong, non-minimal coupling to gravity variety of these models, identifying a shift of the attractor from the expected Starobinsky point and determining conditions for approach...
Andrew Long
(KICP, United States)
09/09/2015, 10:20
The discovery of a cosmic string network would provide compelling evidence for a symmetry-breaking phase transition in the early universe, and thereby further our understanding of particle physics at high energies with implications for baryogenesis, magnetogenesis, inflation, and string theory. Whereas high tension string networks, such as those associated with a GUT-scale phase transition,...
Sebastien clesse
(University of Namur, Belgium)
09/09/2015, 10:20
A scenario where massive Primordial Black Holes (PBH) are produced from the collapse of large curvature perturbations generated during a mild waterfall phase of hybrid inflation will be presented. I will give the values of the inflaton potential parameters leading to a PBH mass spectrum producing abundances comparable to those of Dark Matter today, while the matter power spectrum on scales...
Juan Carlos Bueno Sanchez
(Universidad Antonio Narino, Colombia)
09/09/2015, 11:10
The contribution of cosmological vector fields to the CMB is strongly constrained by the bound on the anisotropy parameter g, allowing a direction-dependent contribution only to a puny 0.2% level, thus establishing the global isotropy of the CMB to high precission. In this talk I present a scenario whereby a vector field, produced during inflation and free from ghost and perturbative...
Jonathan Braden
(University College London, United Kingdom)
09/09/2015, 11:10
First-order phase transitions proceed through the nucleation and subsequent collision of bubbles. In false vacuum eternal inflation, such collision events are ubiquitous and provide a possible avenue to observationally test the multiverse. They also play an important role in early high temperature phase transitions.
I will present results for the full three-dimensional nonlinear dynamics...
Sami Nurmi
(University of Jyvaskyla, Finland)
09/09/2015, 11:30
If the Higgs potential remains close to the Standard Model prediction the light Higgs field gets locally displaced from vacuum during inflation. Observational ramifications of the primordial Higgs condensate crucially depend on its subsequent evolution. We discuss the relaxation of the condensate using analytical methods and numerical lattice computations. The dominant decay channel is the...
Sander Mooij
(FCFM, Universidad de Chile, Chile)
09/09/2015, 11:30
We study the renormalization of theories with large non-minimal scalar-gravity coupling, of which Higgs inflation (inflation with the Higgs field playing the role of the inflaton) is the most prominent example. Despite the popularity of these models, their renormalization has never been worked out systematically. We provide an on-shell renormalization scheme, organized as an expansion in...
Subodh Patil
(University of Geneva, Switzerland)
09/09/2015, 11:50
Although detecting primordial non-Gaussianity (NG) would provide an incredibly rich window onto the interaction physics of the inflaton, one might wonder what we could conclude about its nature if all we end up observing is consistent with adiabatic, Gaussian and scale invariant initial conditions. In this talk we highlight how in principle, one can still infer a great deal. Fields that are...
Ippocratis Saltas
(University of Lisbon, Portugal)
09/09/2015, 11:50
In this talk, I will discuss about one of the most sucesfull inflationary models according to the latest Planck data, namely the Starobinskys model. I will focus on the significance of quantum corrections in this context, and how this model could be understood as part of a more fundamental framework.
Sebastien Renaux-Petel
(IAP, France)
09/09/2015, 12:10
The simplest single-field models of inflation are sufficient to explain the cosmological data. However, inflation is an ultraviolet-sensitive phenomenon, and embedding inflation into high-energy physics requires taking into account the possible effects on inflation of heavy scalar fields. Model-builders usually assume or construct potentials such that they are stabilized by a potential well....
Germano Nardini
(DESY, Germany)
09/09/2015, 12:10
In many extensions of the Standard Model of particle physics (SM) the LHC experimental data impose a stringent bound on the strength of the electroweak phase transition and, in turn, on the stochastic gravitational waves background that this transition can produce. In this talk we consider a simple supersymmetric extension of the SM and we identify a parameter region where the electroweak...
Tomi Koivisto
(Nordita, Sweden)
09/09/2015, 12:30
A generalisation of the Weyl geometry, where the non-metricity and torsion are given by a single vector field, is presented.
Taking into account the leading (quadratic) curvature correction in this geometry results in a one-parameter extension of the Starobinsky inflation, the so-called alpha-attractor model.
Pedro Gregorio Carrilho
(Queen Mary University of London, United Kingdom)
09/09/2015, 12:30
We derive the evolution equation for the second order part of the curvature perturbation using standard techniques of cosmological perturbation theory. The result is valid at all scales and includes all contributions from vector and tensor perturbations, as well as anisotropic stress. We write all our results purely in terms of gauge invariant quantities, so as to facilitate future work in any...
Florian Kuhnel
(The Oskar Klein Centre, Sweden)
10/09/2015, 14:00
In my talk, I will first introduce the corpuscular framework, recently proposed by Gia Dvali and Cesar Gomez, in which space-time is described in terms of graviton Bose-Einstein condensates.
Then I will present our recent quantitative investigations on this model regarding its cosmological implications, and will show how the cosmic microwave background power spectrum and the tensor-to-scalar...
Evangelos Sfakianakis
(University of Illinois at Urbana-Champaign, United States)
10/09/2015, 14:20
Axions are attractive candidates for theories of large-field inflation that are capable of generating observable primordial gravitational wave backgrounds. These fields enjoy shift-symmetries that protect their role as inflatons from being spoiled by coupling to unknown UV physics. This symmetry also restricts the couplings of these axions to other matter fields. At lowest order, the only...
Yusuke Yamada
(Waseda University, Japan)
10/09/2015, 14:40
We investigate the inflation model with a massive vector multiplet in a case that the action of the vector multiplet is extended to the Dirac-Born-Infeld (DBI) type one in 4 dimensional N=1 supergravity. We show the massive DBI action, and find that the higher order corrections associated with the DBI-extension make the scalar potential flat with a simple choice of the matter couplings. We...
Kyohei Mukaida
(Kavli IPMU, Japan)
10/09/2015, 15:00
After inflation, inflaton converts its huge energy into radiation to create the hot Universe, which is referred to as reheating. Naively, one might guess that radiation produced via reheating soon attains the thermal distribution within the Hubble time. Under this instantaneous thermalization assumption, many attractive thermal mechanisms were proposed so far; such as thermal leptogenesis,...
David Weir
(University of Stavanger, Norway)
10/09/2015, 15:20
We present large-scale numerical simulations of the gravitational radiation produced by a first order phase transition in the early universe. We show that the dominant source of gravitational waves is sound waves generated by the expanding bubbles of the low-temperature phase. The sound waves have a power spectrum with power-law form between scales set by the average bubble separation and the...
Marco Scalisi
(Van Swinderen Institute - University of Groningen, Netherlands)
10/09/2015, 16:10
The Planck value of the spectral index can be interpreted as ns=1−2/N in terms of the number of e-foldings N. An appealing explanation for this phenomenological observation is provided by α-attractors: the inflationary predictions of these supergravity models are fully determined by the curvature of the Kahler manifold. We provide a unified description of cosmological α-attractors and...
Gonzalo Palma
(FCFM, Universidad de Chile, Chile)
10/09/2015, 16:30
We discuss the generation of sharp features in the primordial spectra within the framework of effective field theory of inflation, wherein curvature perturbations are the consequence of the dynamics of a single scalar degree of freedom. We identify two sources in the generation of features: the time-variation of the sound speed of curvature fluctuations c_s and the time-variation of the...
Tommi Markkanen
(Imperial College, United Kingdom)
10/09/2015, 16:50
The best fit values for the SM parameters imply that the potential for the Higgs boson developes a Planck-scale vacuum with negative energy, which may result in decay of the current vacuum state. In this talk we show the significance of backreaction from classical gravity for vacuum stability during and after inflation. In particular we show that requiring stability, inflation constrains the...
Oleg Ruchayskiy
(EPFL, Switzerland)
10/09/2015, 17:10
In this talk I will present new results about generation and evolution of
cosmological magnetic fields, showing that some of our basic assumptions about
the primordial plasma are violated when helical magnetic fields are present in
it. The consequences for survival of the magnetic fields and effects on the
processes like leptogenesis will also be discussed.
Marco Drewes
(TU Munich, Germany)
10/09/2015, 17:30
We study experimental and cosmological constraints on the extension of the Standard Model by three right handed neutrinos with masses between those of the pion and W-boson. This low scale seesaw scenario allows to simultaneously explain the observed neutrino oscillations and the baryon asymmetry of the universe. We combine indirect experimental constraints from neutrinoless double β-decay,...
Yohei Ema
(The University of Tokyo, Japan)
10/09/2015, 17:50
Ryusuke Jinno
(The University of Tokyo, Japan)
11/09/2015, 14:00
Inflaton inevitably couples to all non-conformally coupled matters to gravity, through an oscillation in the Hubble parameter or the cosmic scale factor. This coupling leads to particle production during the inflaton oscillation regime even in the minimal (Einstein-Hilbert action + canonical inflaton) setup. In addition, such particle production due to the oscillation in the Hubble parameter...
Shelley Liang
(School of Physics, University of Sydney, Australia)
11/09/2015, 14:00
We propose a minimal, scale invariant model for dynamical electroweak symmetry breaking via top condensation. The classical scale invariance is realized nonlinearly by introducing conformal compensator scalar field, the (pseudo)dilaton, which plays crucial role in a successful prediction for the Higgs boson and top quark masses. We also argue that the fine-tuning problem of the ordinary top...
Kouichirou Horiguchi
(Nagoya University, Japan)
11/09/2015, 14:20
A symmetry-breaking phase transition in the early universe could have led to the formation of cosmic defects. Because these defects dynamically excite not only scalar and tensor type cosmological perturbations but also vector type ones, they may serve as a source of primordial magnetic fields.
In this study, we calculate the time evolution and the spectrum of magnetic fields from two types...
Ryo Namba
(Kavli IPMU, Japan)
11/09/2015, 14:20
There has recently been a growing evidence for the existence of magnetic fields in the extra-galactic regions, while the attempt to associate it only with the inflationary epoch has been found extremely challenging. We thus take into account the post-inflationary evolution of the magnetic fields originated from vacuum fluctuations during inflation. We consider the model in which the inflaton...
Teruaki Suyama
(Research Center for the Early Universe, University of Tokyo, Japan)
11/09/2015, 14:40
We propose a mechanism of producing new type of primordial perturbation from which primordial black holes whose mass is comparable to the supermassive black holes observed at high redshifts are produced. The observable Universe consists of two kinds of many small patches which experienced different history during inflation. Large amplitude of the primordial perturbation enough to form...
Sebastian Mendizabal
(Universidad Tecnica Federico Santa Maria, Chile)
11/09/2015, 14:40
Thermal Leptogenesis gives a simple and elegant solution to the baryon asymmetry in the universe problem. In this scenario the CP-violating thermal decay of a very massive Majorana neutrino accounts for this asymmetry. This mechanism requires high temperature and a strongly coupled electro-weak primordial bath. We will show a novel way to treat corrections that arises when the strong...
Jose Pedro Pinto Vieira
(Mathematical and Physical Sciences, University of Sussex, United Kingdom)
11/09/2015, 15:00
Negative absolute temperatures are an exotic thermodynamical consequence of quantum physics which has been known since the 1950's (having been achieved in the lab on a number of occasions). Recently, the work of Braun et al (Science, 2013) has not only rekindled interest in these counter-intuitive regimes but also sparked a debate which has forced a revision of the very foundations of...
Grigorios Panotopoulos
(Department of Physics, University of Chile, Chile)
11/09/2015, 15:00
In the present work we show that warm chaotic inflation characterized by a simple
$\frac{\lambda}{4}\phi^{4}$
self-interaction potential for the inflaton, excluded by current
data in standard cold inflation, and by an inflaton decay rate proportional
to the temperature, is in agreement with the latest Planck data.
The parameters of the model are constrained, and our results show that the
model...
Andrew Long
(KICP, United States)
11/09/2015, 15:20
It is customary and often necessary to study cosmological phase transitions, such as inflation and thermal symmetry-breaking phenomena, through the relics they leave behind. A relic magnetic field, for instance, could have been sustained by the hot plasma of the early universe and provide the seed for galactic-scale fields seen today. Evidence for this primordial magnetic field may be found...
Seishi ENOMOTO
(Faculty of Physics, University of Warsaw, Poland)
11/09/2015, 15:20
We have investigated effects of interaction terms on non-perturbative particle production. It is well known that a time-varying background induces abundant particle production, such as the preheating theory. As our conclusion, it is possible to induce particle production even if particles do not couple to the background directly. Such particles are produced through the interactions with other...
