Leszek Roszkowski
(National Centre for Nuclear Research, Poland)
07/09/2015, 09:00
Grzegorz Wrochna
(National Centre for Nuclear Research, Poland)
07/09/2015, 09:10
Igor Moskalenko
(Stanford University, United States)
07/09/2015, 09:15
Shirley Ho
(Carnegie Mellon University, United States)
07/09/2015, 09:50
John Beacom
(Ohio State University, United States)
07/09/2015, 10:55
Stephen King
(University of Southampton, United Kingdom)
07/09/2015, 11:30
Mikhail Shaposhnikov
(EPFL, Switzerland)
07/09/2015, 12:05
Matteo Viel
(INAF OATs, Italy)
07/09/2015, 14:00
Debora Sijacki
(University of Cambridge, United Kingdom)
07/09/2015, 14:35
Katherine Freese
(Nordita, Sweden and University of Michigan, United States)
07/09/2015, 15:10
Ki-Young Choi
(KASI, Republic of Korea)
07/09/2015, 16:15
Marc Schumann
(University of Bern, Switzerland)
07/09/2015, 16:50
Miguel Sanchez-Condé
(Oskar Klein Centre and Stockholm University, Sweden)
07/09/2015, 17:25
Torsten Bringmann
(University of Oslo, Norway)
08/09/2015, 09:00
Anthony Challinor
(University of Cambridge, United Kingdom)
08/09/2015, 10:40
Ruth Durrer
(Universite de Geneve, Switzerland)
08/09/2015, 11:15
Edward Malec
(Institute of Physics Jagiellonian University, Poland)
08/09/2015, 11:50
Krzysztof Bielas
(Institute of Physics, University of Silesia, Poland)
08/09/2015, 12:30
We use the 'local weakening of logic in a spacetime' as a mathematical tool suitable also for building cosmological models. The models extend the regular spacetime solutions of Einstein equations towards solutions with certain spacetime singularities. Such models are also natural for addressing the renormalization questions of various quantum field theories. We discuss this issue...
Mateja Gosenca
(Astronomy Centre, School of Mathematical and Physical Sciences, University of Sussex, United Kingdom)
08/09/2015, 12:31
N-body simulations normally use equations of Newtonian dynamics to evolve particles and fields forward in time. On galactic scales and at times late enough for velocities and gradients of fields to be small this turns out to be an extremely good approximation. However, in modified gravity models, at earlier times when neutrinos are relativistic, or on much larger scales, evolving relativistic...
Ludwik Kostro
(Ateneum-University in Gdansk, Poland)
08/09/2015, 12:32
The Lambda Units determined by three Einstein's constants: velocity of light, his gravitational constant and his lambda cosmological constant will be introduced. Some of them are already used in relativistic cosmology e.g. lambda density of mass and the pressure of the physical vacuum . Other Units like e.g. lambda quantum of action i.e. the inverse of the product of the mentioned above three...
Manuel Arca Sedda
(University of Rome La Sapienza, Italy)
08/09/2015, 12:33
In this contribution we discuss how the centres of galaxy clusters evolve in time, showing the results of a series of direct N-body modelling at high resolution.
In particular, we followed the evolution of a galaxy cluster with a mass of around 10^14 solar masses in four different configurations: 1) isolated cluster; 2) cluster subjected to the action of Dark Energy; 3) cluster composed of...
Giulia Cusin
(Département de Physique Théorique and Center for Astroparticle Physics, University of Geneva, Switzerland)
08/09/2015, 12:34
We introduce a new formalism to study perturbations of Hassan-Rosen bigravity theory, around general backgrounds for the two dynamical metrics. In particular, we derive the general expression for the mass term and we explicitly compute it for some cosmological settings. We study in detail tensor perturbations in branch-one bigravity using this formalism. We show that the tensor sector is...
Luisa Jaime
(Institute for Theoretical Physics, Heidelberg University, Germany)
08/09/2015, 12:35
We introduce a different approach in f(R) gravity. Our approach avoids the mapping to scalar tensor theories using the Ricci scalar itself as an 'extra' degree of freedom. In this talk we will present this formalism and we will analyze the equation of state (EOS) of the geometric dark energy related with the extra terms in f(R), including the comparison of several EOS that have been proposed...
Nobuyoshi Ohta
(Department of Physics, Kinki University, Japan)
08/09/2015, 12:36
We study gravitational theories with a cosmological constant and the Gauss-Bonnet curvature squared term and analyze the possibility of de Sitter expanding spacetime with a constant internal space. We find that there are two branches of the de Sitter solutions: Both the curvature of the internal space and the cosmological constant are (1) positive and (2) negative. From the stability analysis,...
Yasuho Yamashita
(Yukawa Institute for Theoritical Physics, Japan)
08/09/2015, 12:37
Recently the ghost-free bigravity, the gravitational theory which contains two metrics interacting each other, is constructed by tuning the interaction terms to remove Boulware-Deser ghost. Using this model, we can realize the late-time cosmic accelerating expansion and the gravitational wave has a charasteristic feature.
However, we have no idea what is the mechanism which tunes the...
Sebastian Zell
(Department of Physics, Ludwig-Maximilians-Universitaet Muenchen, Germany)
08/09/2015, 12:38
We follow the corpuscular approach proposed by Dvali and Gomez, in which N universally characterizes gravitational backgrounds (with N = (Mp)^2/Λ for de Sitter spacetime). In doing so, we explicitly draw a fully quantum picture of the background metric in the limit of weak gravity. Using coherent states in each mode, we show that it can be understood as collective effect of soft,...
Martina Donnari
(Department of Physics, University of Rome La Sapienza, Italy)
08/09/2015, 12:39
Systems of selfgravitating Fermions constitute a topic of great interest in astrophysics, due to the wide range of applications, and are used also to explain dark matter in galaxies and clusters of galaxies. Here, we study the gravitational equilibrium of spherical models describing a semidegenerate collisionless gas. The Fermi-Dirac distribution function, modified by a cutoff term in order to...
Sebastian Trojanowski
(National Centre for Nuclear Research, Poland)
08/09/2015, 12:40
I will examine the relic abundance of supersymmetric dark matter in a scenario where the reheating temperature T_R of the Universe after inflation is low, in the range of tens or of hundreds of GeV. To this end I will solve the Boltzmann equation during and after the period of reheating, taking into account cosmological as well as collider constraints, in particular the recent Higgs boson...
Andrew Williams
(National Centre for Nuclear Research, Poland)
08/09/2015, 12:41
We analyse the sensitivity of the future Cherenkov Telescope Array (CTA) experiment to dark matter annihilations in the galactic centre using the most up to date instrument response functions and background simulation model provided by the CTA Collaboration. We systematically examine the different statistical methods for setting limits using CTA and provide a realistic assessment of the...
Sam Young
(Physics and Astronomy, University of Sussex, United Kingdom)
08/09/2015, 12:42
Primordial black holes may have formed very early on during the radiation dominated era in the early universe, and are normally used to probe the small scale perturbations formed towards the end of inflation. I will present a method by which the large scale perturbations in the number density of primordial black holes may be used to place tight constraints on non-gaussianity if PBHs account...
Yugo Abe
(Shinshu University, Japan)
08/09/2015, 12:44
We study whether the inflation is realized based on the radion gauge-Higgs potential obtained from the one-loop calculation in the 5-dimensional gravity coupled to a U(1) gauge theory.
We show that the gauge-Higgs can give rise to inflation in accord with the astrophysical data and the radion plays a role in fixing the values of physical parameters.
We clarify the reason why the radion...
Lukasz Dulny
(Faculty of Physics, University of Warsaw, Poland)
08/09/2015, 12:45
Equations of motion in slow roll inflationary models with two scalar fields for scalar perturbations metrics were analysed for an example of turning valley in scalar potential with non-canonical kinetic term. The impact of the multi-scale dynamics on the sub-horizon evolution of the perturbations was studied with a special emphasis on the (lack of) decoupling of the large scale modes and...
Vera-Maria Enckell
(Department of Physics, University of Helsinki, Finland)
08/09/2015, 12:47
It has been shown that Higgs inflation could be realized even if the Higgs potential has a negative energy minimum separating the inflationary part from the low-energy SM regime. The precise shape of the potential is dictated by the running of the couplings which necessarily differs from SM predictions at high-energies. We explore how the high-energy running affects the details of the...
Olga Czerwinska
(University of Warsaw, Poland)
08/09/2015, 12:48
It is known that time-dependent vacuum expectation value of the background field causes the production of particles, in the expanding universe this process is also influenced by the time-dependence of the scale factor. Poster would present the general mechanism of particle production in time-varying backgrounds with the impact of rescattering emphasised, also in models with more than one...
Taro Kunimitsu
(RESCEU University of Tokyo, Japan)
08/09/2015, 12:49
We systematically show that in potential driven generalized G-inflation models, quantum corrections coming from new physics at the strong coupling scale can be avoided, while producing observable tensor modes. The effective action can be approximated by the tree level action, and as a result, these models are internally consistent, despite the fact that we introduced new mass scales below the...
Stefano Orani
(University of Basel, Switzerland)
08/09/2015, 12:51
In 'hilltop inflation', inflation takes place when the inflaton field slowly rolls from close to a maximum of its potential (i.e. the 'hilltop') towards its minimum. When the inflaton potential is associated with a phase transition, possible topological defects produced during this phase transition, such as domain walls, are efficiently diluted during inflation. It is typically assumed that...
Mauro Pieroni
(AstroParticle and Cosmology laboratory, Paris Diderot University-Paris 7, France)
08/09/2015, 12:52
In some recent papers it was proved that the cosmological evolution of a scalar field in a potential can be descirbed in terms of a renormalisation group equation. The slow rolling regime of the inflaton can be compared with the slow departure from a fixed point of the beta function in the RG group context.
This can be seen as an effective approach to the problem in the sense that the...
Christopher Harman
(University of Sussex, United Kingdom)
08/09/2015, 12:53
Taking on a new perspective of the electroweak phase transition, we investigate a quantity called the one loop zero temperature vacuum energy difference. This quantity allows us to address all manner of features that are known to give rise to a strong first order electroweak phase transition. Our study is conducted using six extensions to the Standard Model of varying complexity,...
Kohji Yajima
(Department of Physics, Rikkyo University, Japan)
08/09/2015, 12:54
We consider a squared term of Weyl tensor in the Einstein-Hilbert’s action. It is one kind of the theories about higher curvature invariants in the action as quantum corrections. In general, such additional terms generate ghost degrees of freedom. But the theory we consider here is ghost free by breaking local Lorentz symmetry. Using this theory, we consider gravitational waves from slow-roll...
Laura Taddei
(ITP Heidelberg, Germany)
08/09/2015, 12:55
Most cosmological constraints on modified gravity are obtained assuming that the cosmic evolution
was standard CDM in the past and that the present matter density and power spectrum
normalization are the same as in a CDM model. Here we examine how the constraints change
when these assumptions are lifted. We focus in particular on the parameter Y (also called G_effective ) that
quanties the...
David Weir
(University of Stavanger, Norway)
08/09/2015, 12:56
Eric Linder
(UC Berkeley, United States)
08/09/2015, 14:00
Cosmic microwave background lensing has become a new cosmological probe, carrying rich information on the matter power spectrum and distances over the redshift range z≈1-4. We investigate the role of scale dependent new physics, such as from modified gravity, neutrino mass, and cold (low sound speed) dark energy, and its signature on CMB lensing. The distinction between different scale...
Matteo Fasiello
(Stanford University, United States)
08/09/2015, 14:00
The quest for a stable, compelling, cosmology of massive gravity. I will introduce some of the everyday tools of massive (bi)gravity and then illustrate the latest developements. Particular attention will be devoted to the so-called generalized massive gravity model, its observational viability as well as its stability as a qft.
Stefano Camera
(Jodrell Bank Centre for Astrophysics, United Kingdom)
08/09/2015, 14:00
Both gravitational lensing and cosmological gamma-ray emission stem from the presence of dark matter (DM) in the universe. Indeed DM structures are responsible for the bending of light due to the gravitational lensing effect, and those same objects can emit gamma rays, either because they host astrophysical sources or directly by particle DM annihilations/decays. Such gamma rays should...
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...
Enrico Maria Sessolo
(National Centre for Nuclear Research, Poland)
08/09/2015, 14:20
We investigate the prospects for detection of neutralino dark matter in the 19-parameter phenomenological MSSM (pMSSM). We explore very wide ranges of the pMSSM parameters but pay particular attention to the higgsino-like neutralino at the 1 TeV scale, which has been shown to be a well motivated solution in many constrained supersymmetric models, as well as to a wino-dominated solution with...
Laura Sagunski
(DESY, Germany)
08/09/2015, 14:20
We study soft limits of correlation functions for the density and velocity fields in
the theory of structure formation. First, we re-derive the (resummed) consistency conditions
at unequal times using the eikonal approximation. These are solely based on symmetry
arguments and are therefore universal. Then, we explore the existence of equal-time relations
in the soft limit which, on the other...
Benedict Broy
(Theory Group, DESY, Germany)
08/09/2015, 14:20
Motivated by UV realisations of Starobinsky-like inflation models, we study generic exponential plateau-like potentials to understand whether an exact $f(R)$-formulation may still be obtained when the asymptotic shift-symmetry of the potential is broken for larger field values. Potentials which break the shift symmetry with rising exponentials at large field values only allow for corresponding...
Alejandro Lopez
(University of Michigan, United States)
08/09/2015, 14:40
The Fermi/LAT experiment measures a spherically symmetric excess in gamma-ray flux from the Galactic Center. The gamma-ray excess could be explained by annihilating dark matter. We aim to explain the Galactic Center Excess (GCE) via a neutralino in resonance with the higgs pseudoscalar. The MSSM parameter spaced is scanned in order to find the best fit to the gamma-ray flux signal measured at...
Patrick Breysse
(Johns Hopkins University, United States)
08/09/2015, 14:40
Intensity mapping is a promising new technique for studying the large-scale structure of the universe at redshifts inaccessible to traditional galaxy surveys. Intensity mapping studies typically focus on two-point statistics of a map such as the power spectrum. However, because these maps are highly non-Gaussian, there is a wealth of additional information which can be obtained by studying...
Ryo Saito
(Laboratoire APC, France)
08/09/2015, 14:40
Many theories of modified gravity, including the well studied Horndeski models, are characterized by a screening mechanism that ensures that standard gravity is recovered near astrophysical bodies. In a recently introduced class of gravitational theories that goes beyond Horndeski, it has been found that new derivative interactions lead to a partial breaking of the Vainshtein screening...
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...
Vincenzo Salzano
(University of Szczecin, Poland)
08/09/2015, 15:00
We describe a new method to use Baryon Acoustic Oscillations to derive a constraint on the possible variation of the speed of light. The method relies on the fact that there is a simple relation between the angular diameter distance maximum and the Hubble function evaluated at the same maximum-condition redshift, which includes speed of light c. We evaluate if current or future missions can be...
Sandrine Schloegel
(UNamur, Belgium)
08/09/2015, 15:00
Current acceleration of the cosmic expansion leads to co%u010Fncidence as well as fine-tuning issues in the framework of general relativity. Dynamical scalar field
have been introduced in response of these problems, some of them invoking screening mechanisms for passing local tests of gravity. Recent lab experiments based on atom interferometry in a vacuum chamber have been proposed for...
Andrzej Hryczuk
(TU Munich, Germany)
08/09/2015, 15:00
We will discuss the relic density of TeV-scale neutralino dark matter in the pMSSM. We have recently developed a framework enabling us to calculate the Sommerfeld enhanced relic density in general pMSSM scenarios. We will present the results of a thorough investigation of certain regions of parameter space, focussing in particular on departures from the well known pure wino scenario: namely...
Kazufumi Takahashi
(RESCEU The University of Tokyo, Japan)
08/09/2015, 15:20
f(R) gravity is one of the simplest generalizations of general relativity, which may explain the accelerated cosmic expansion without introducing a cosmological constant. Transformed into the Einstein frame, a new scalar degree of freedom appears and it couples with matter fields. In order for f(R) theories to pass the local tests of general relativity, it has been known that the chameleon...
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...
Maciej Gorski
(National Centre for Nuclear Research, Poland)
08/09/2015, 15:20
Hu Zhan
(National Astronomical Observatories of China, China)
08/09/2015, 15:20
Non-parametric reconstruction is useful for constraining quantities that are potentially varying with time. A common practice is to replace the continuous function with an interpolation over a set of points or bins. This approach often involves many degrees of freedom, so that the constraints become too weak to be informative. In this presentation, we discuss priors that can help reduce the...
Frank Koennig
(Institut fuer Theoretische Physik -Uni Heidelberg, Germany)
08/09/2015, 16:10
Bimetric theory describes gravitational interactions in the presence of an extra
spin-2 field. It allows for many different types of cosmological
solutions but not all of them are theoretically allowed, most of them are
generically plagued by instabilities. We discuss the
conditions of the absence of these ghost- and gradient instabilities and present
a ghost-free model in which the gradient...
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...
Jon Gudmundsson
(Stockholm University, Sweden)
08/09/2015, 16:10
SPIDER is a balloon-borne experiment designed to image the polarization of the cosmic microwave background with the aim of constraining models of the early universe. The experiment performed successfully during a 17 day flight in the 2014-2015 Antarctic season. During this first flight, SPIDER deployed a total of 2000 detectors, operating at 94 and 150 GHz, to map approximately 10% of the sky...
Antonella Garzilli
(Leiden University, Netherlands)
08/09/2015, 16:10
We reconsider the problem of determining the warmness of
dark matter from the Lyman-alpha forest. In particular, we have
re-analyzed the previous work of Viel et al 2013, based on high
resolution Lyman-alpha forest spectra. We allow different cosmic
thermal history than the one considered in the previous work; these
cosmic thermal history are in agreement with other theoretical...
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...
Martin Krauss
(INFN - Laboratori Nazionali di Frascati, Italy)
08/09/2015, 16:30
n the early Universe, any particle carrying a conserved quantum number and in chemical equilibrium with the thermal bath will unavoidably inherit a particle-antiparticle asymmetry. A new particle of this type, if stable, would represent a candidate for asymmetric dark matter (DM) with an asymmetry directly related to the baryon asymmetry. We study this possibility for a minimal DM sector...
Moritz Munchmeyer
(Universite Pierre et Marie Curie, Institute Astrophysique de Paris, France)
08/09/2015, 16:30
Oscillating signatures in the correlation functions of the primordial density perturbations are predicted by a variety of inflationary models. A theoretical mechanism that has attracted much attention is a periodic shift symmetry as implemented in axion monodromy inflation. This symmetry leads to resonance non-gaussianities, whose key feature are logarithmically stretched oscillations....
Alexandra Terrana
(York University, Canada)
08/09/2015, 16:30
Massive bigravity, a theoretically consistent modification of general relativity with an additional dynamical rank two tensor, successfully describes the observed accelerated expansion of the Universe without a cosmological constant. Previous analyses of perturbations around a cosmological background have revealed power law instabilities in both the scalar and tensor sectors, leading to...
Takashi Hiramatsu
(Kyoto University, Japan)
08/09/2015, 16:50
Cosmic Microwave Background (CMB) is known as a remnant of Big-Bang, and lots of past works in cosmology have paid attention to its potential to
prove the very early Universe. In these days, our main interests moved to quite fine structures of the Universe, for instance, the statistical properties of the
primordial fluctuations constructing the large-scale structure, and in fact we can...
Henrik Nersisyan
(Heidelberg University ITP, Germany)
08/09/2015, 16:50
Massive bigravity models are interesting alternatives to standard cosmology. In most cases however these models have been studied for a simplified scenario in which both metrics take homogeneous and isotropic forms (Friedmann-Lemaitre-Robertson-Walker; FLRW) with the same spatial curvatures.The interest to consider more general geometries arises in particular in view of the difficulty so far...
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...
Christopher Geis
(Johannes Gutenberg-University Mainz, Germany)
08/09/2015, 16:50
The XENON suite of experiments, situated at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy, aim at the direct detection of Dark Matter in the form of WIMPs (Weakly Interacting Massive Particles) via their elastic scattering off xenon nuclei. The detector concept is based on a dual phase liquid xenon time projection chamber.
The currently operating phase of the XENON Dark Matter...
Marieke Postma
(Nikhef, Netherlands)
08/09/2015, 17:10
If dark matter couples directly to a light force mediator, then it may form bound states in the early universe and in the non-relativistic environment of haloes today. In this talk I will present a field-theoretic framework for the computation of bound-state formation cross-sections, de-excitation and decay rates, in theories with long-range interactions. At low relative velocities of the...
Ana Caterina Leite
(Centro de Astrofísica da Universidade do Porto, Portugal)
08/09/2015, 17:10
We recently extended Principal Component Analysis based methods to constrain the dark energy equation of state (originally developed for Type Ia supernovae and other low redshift probes) to spectroscopic tests of the stability of fundamental couplings, which can probe higher redshifts. In this talk I will use these methods to quantify the gains in sensitivity obtained by combining...
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...
Agnieska Cieplak
(Brookhaven National Laboratory, United States)
08/09/2015, 17:10
With the recent progress of Lyman-alpha forest power spectrum
measurements, understanding of the bias between the measured flux and
the underlying matter power spectrum is becoming crucial to the
percent level cosmological interpretation of these measurements.
Previous theoretical studies of this bias have used N-body and
hydro-PM simulations and inferred large-scale bias parameters that...
Savvas Koushiappas
(Brown University, United States)
08/09/2015, 17:30
I will present results from a search for gamma-ray emission in nine Milky Way satellites recently discovered in the Dark Energy Survey. The nearest of these, Reticulum 2, shows evidence for a signal in public Fermi data. The detected emission is consistent with annihilating dark matter with a particle mass less than a few hundred GeV. Different ways of treating the background yield different...
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...
Alessio Notari
(Universitat de Barcelona, Spain)
08/09/2015, 17:30
I review several possible Anomalies for the Planck CMB data: the hemispherical power asymmetry, dipolar modulation and quadrupole-octupole alignments. I show that they are significantly affected by our proper motion. I also point out that the latter issue might be relevant also for the Calibration of the HFI instrument itself.
Marco Raveri
(SISSA, Italy)
08/09/2015, 17:30
I will discuss the relevance of the Effective Field Theory (EFT) approach in testing modified gravity and dark energy models that aim at solving the problem of cosmic acceleration.
In particular I will review the EFT construction and its implementation into the Einstein-Boltzmann solver EFTCAMB that is a powerful and versatile tool that can be used for several objectives. It can be employed to...
Daniel Guariento
(Perimeter Institute for Theoretical Physics, Canada)
08/09/2015, 17:50
The generalized McVittie solution, representing a central time-dependent mass in an expanding cosmological background, has been shown to be an exact solution of a self-gravitating subset of the Horndeski class of scalar field actions, and constitutes an important example of an analytic solution for hairy black holes. Following the analysis performed on its fixed-mass counterpart, we...
Daisuke Yoshida
(Tokyo Institute of Technology, Japan)
08/09/2015, 17:50
We investigate perturbations of a class of time-dependent spherically symmetric solutions in bi-gravity, which includes both FLRW space time and Schwarzschild de Sitter space time.
We consider the solutions which can be obtained only when the parameters of bi-gravity satisfy a special relation. In this case, It is known that the equation of motion for spherically symmetric space time reduces...
Caroline Heneka
(Dark Cosmology Centre, Denmark)
08/09/2015, 17:50
Clustering dark energy presents interesting phenomonology in comparison to standard homogeneous dark energy models. We investigate the impact of clustering dark energy on structure formation. Employing the spherical collapse formalism we obtain the collapse and virial density thresholds, as well as additional mass contributions due to non-linear dark energy perturbations. For an accurate...
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...
Alexander Leithes
(Queen Mary University of London, United Kingdom)
09/09/2015, 09:00
In this talk I will outline our research into the evolution of perturbations in coupled quintessence with multiple fluids and scalar fields. I will explain what coupled quintessence is and why it is of interest and will introduce a new Python code developed by myself in conjunction with my collaborators. There are a vast number of different coupled quintessence models and potentials and we...
Siri Chongchitnan
(University of Hull, United Kingdom)
09/09/2015, 09:00
Cosmic voids have been shown to be an effective probe of cosmology, complementary to galaxy clusters. But how reliable are the current theoretical models for void abundance?
In this talk, I will explain how the theory of "extreme cosmic voids" can be used as a consistency test for theories of void abundance. I will give a simple derivation of the size of the largest voids expected within a...
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...
Aleksandra Piorkowska
(University of Silesia, Poland)
09/09/2015, 09:20
In the era of massive galactic surveys, strong gravitational lensing systems have entered a stage in which we observe their growing significance in astrophysics and cosmology.
In our work we present a catalog of 118 strong gravitational lensing systems built on SLACS, BELLS, LSD and SL2S samples and we use them to demonstrates that strong lensing data provide a good quality tool for...
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...
Tom Charnock
(University of Nottingham, United Kingdom)
09/09/2015, 09:20
There is a tension between measurements of the amplitude of the power spectrum of density perturbations inferred using the Cosmic Microwave Background (CMB) and directly measured by Large-Scale Structure (LSS) on smaller scales. We show that this tension exists, and is robust, for a range of LSS indicators including clusters, lensing and redshift space distortions and using CMB data. One...
Elina Palmgren
(Helsinki institute of physics, Finland)
09/09/2015, 09:40
This presentation will introduce the research [1] in which we employed the Planck CMB temperature anisotropy and lensing data, and baryon acoustic oscillation (BAO) data to constrain a phenomenological $w$CDM model, where dark matter and dark energy interact. We assumed time-dependent equation of state parameter for dark energy, and treated dark matter and dark energy as fluids whose...
Robert Crittenden
(Institute of Cosmology and Gravitation, United Kingdom)
09/09/2015, 09:40
We present a simple model for describing intrinsic correlations for galaxy sizes based on the halo model. Studying these correlations is important both to improve our understanding of galaxy properties and because it is an important potential systematic for weak lensing size magnification measurements. Our model assumes that the density field drives these intrinsic correlations and we also...
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...
Giuseppe Fanizza
(Universita di Bari, Italy)
09/09/2015, 10:00
We present a new method to compute the deflection of light rays in a perturbed FLRW
geometry. By using the properties of the Geodesic Light Cone (GLC) gauge where null rays
propagate at constant angular coordinates irrespectively of the given (inhomogeneous and/or
anisotropic) geometry, the gravitational deflection of null geodesics can then be obtained
in any other gauge. This connection can...
Douglas Spolyar
(Stockholm University OKC, Sweden)
09/09/2015, 10:00
Massive gravity can dynamically and transparently provide of the acceleration of the of the universe,
where the mass of the graviton sets the energy scale of dark enregy. We find the parameter space of massive graivty which easily accomodates the observed acceleration of the Universe by SNa, and BAO with the most recent Planck data. The same parameter space also makes unique predictions for...
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,...
Daniela Saadeh
(University College London, United Kingdom)
09/09/2015, 10:20
Large scales in the Cosmic Microwave Background (CMB) may break statistical isotropy. Bianchi models are often invoked as a possible explanation for these low-\ell features: they provide an anisotropic underlying pattern over which the usual stochastic fluctuations are superimposed. However, the Bianchi models generally employed in the analysis of CMB data — despite mimicking the anomalies in...
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...
Martina Donnari
(Sapienza University of Rome, Italy)
09/09/2015, 10:20
The role of Dark Energy (DE) in the long term evolution of galaxy clusters is the main topic of this talk.
Recently, observational data of the outflow of galaxies in the Virgo cluster, suggest that DE can also act on a small cosmic scales, like a single galaxy cluster.
By means of direct N-body simulations and taking advantage of the latest generation of computational hardware and software,...
Christian Fidler
(CP3 , Belgium)
09/09/2015, 11:10
We discuss different gauge choices and their advantages in the context of N-body simulations. The initial conditions for N-body simulations are usually generated by employing the Zel'dovich approximation. We show that the initial displacements generated in this way generally receive a first-order relativistic correction.
We identify a novel gauge, called N-body gauge in the following, in which...
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...
Mikhail Ivanov
(Ecole Polytechnique Federale de Lausanne, Switzerland)
09/09/2015, 11:10
The large scale structure of the Universe will become the leading observational probe in cosmology in the near future. However, the proper analysis of structure formation at small scales requires non-linear effects to be taken into account. Straightforward attempts to do so within perturbation theory faced several problems such as the appearance of non-physical infra-red (IR) enhancements from...
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...
Alexander Eggemeier
(University of Sussex, United Kingdom)
09/09/2015, 11:30
Correlations in Fourier phases of the cosmological density field arise as a consequence of non-linear structure formation. Since two-point statistics are blind to phase factors, measures of pure phase information will not only be independent of the conventional power spectrum or two-point function, they also do not suffer from Gaussian variance on the modulus of the density field and linear...
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...
Shohei Saga
(Nagoya University, Japan)
09/09/2015, 11:30
The standard cosmological perturbation theory is well established by by a number of observations such as the CMB anisotropy or the Large scales structure.
The standard cosmological perturbation theory includes three independent modes, i.e., scalar, vector, and tensor modes.
The scalar mode is the dominant component in our Universe and has been well determined by cosmological...
Florian Fuehrer
(Institut fuer Theoretische Physik, Germany)
09/09/2015, 11:50
In Growing Neutrino Quintessence strong backreaction effects, induced from large neutrino non-linearities, alter the cosmic history. I will present results obtained from N-body simulations which includes relativistic particles, non-linear scalar field equations and backreaction effects. Including the backreaction effects a realistic cosmology is hard to realize. This points to the need of...
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.
Ignacy Sawicki
(University of Geneva, Switzerland)
09/09/2015, 11:50
There remains a slight but chronic tension between the latest Planck results and low-redshift observables: power seems to be consistently lacking at late times. I will describe how a simple model of dark energy, which has the same expansion history as LCDM, induces a scale-dependent correction to the growth rate of dark matter, suppressing power small scales. Since observations in the late...
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....
Ichihiko Hashimoto
(Kyoto University, Japan)
09/09/2015, 12:10
Detection of primordial non-Gaussianity (PNG) is recognized as a powerful probe of cosmic inflation, and it can give an important clue for the generation mechanism of primordial density fluctuations. In this talk, we specifically consider the local-type PNG and discuss how well one can tightly constrain the higher-order non-Gaussianity parameters (gNL and tauNL) as well as the leading order...
Stefano Anselmi
(Case Western Reserve University, United States)
09/09/2015, 12:10
Cosmology has made fundamental progress thanks to the role of standard rulers. The acoustic peak in the Large Scale Structure clustering correlation function is one of them. However, in the era of precision cosmology, its power has been highly challenged by how late time non-linearities distort the correlation function. Fortunately this is not the end of the story! I will explain how we can...
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...
Pierre Fleury
(IAP, France)
09/09/2015, 12:30
In standard cosmology, observations are interpreted as if light propagated through a universe whose inhomogeneities are modeled by perturbations with respect to the FLRW spacetime. However, the very narrow light beams associated with point-like sources—such as supernovae—probe the Universe at extremely small scales (~AU), up to which the perturbative approach should break down. In this talk, I...
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...
David Polarski
(University Montpellier, France)
10/09/2015, 09:00
Gia Dvali
(Ludwig-Maximilians-Universitaet Muenchen, Germany)
10/09/2015, 09:35
Hans-Peter Nilles
(University of Bonn, Germany)
10/09/2015, 10:40
Raphael Bousso
(UC Berkeley, United States)
10/09/2015, 11:50
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...
Stefano Camera
(Jodrell Bank Centre for Astrophysics, United Kingdom)
10/09/2015, 14:00
Ultra-large cosmic scales supply a wealth of information most valuable for strengthening our knowledge of the Universe. For instance, they can teach us about the physical processes at play during the inflationary epoch, or enable us to either further confirm or rule out Einstein's theory of general relativity. This is because: on the one hand, there are relativistic corrections to the...
Tommi Tenkanen
(University of Helsinki, Finland)
10/09/2015, 14:00
A generic feature of Standard Model extensions with no drastic modifications to the Higgs potential is that the Higgs is a light and energetically subdominant field during inflation. Inflationary fluctuations generically displace the field from its vacuum generating a primordial Higgs condensate. This sets specific out-of-equilibrium initial conditions for the hot big bang epoch which could...
Francesco Pace
(University of Manchester, United Kingdom)
10/09/2015, 14:00
Dark matter and dark energy are usually considered to be two separate components in the energy budget of the Universe. A simple extension to this hypothesis is to consider that they could be different aspects of a single component. This class of models is hence dubbed Unified Dark Matter (UDM) models.
UDM models could cluster and hence give origin to cosmic structures if the adiabatic sound...
Juan Magana
(Institute of Physics and Astronomy Universidad de Valparaiso, Chile)
10/09/2015, 14:20
In this work we constrain four alternative models to explain the late cosmic acceleration in the Universe: Chevallier-Polarski-Linder, interacting dark energy, Ricci holographic dark energy, and modified polytropic Cardassian. To test these models, we use mainly several strong gravitational lensing images of background galaxies produced by the galaxy cluster Abell 1689. We compare the value...
Stephen Barr
(University of Delaware, United States)
10/09/2015, 14:20
Sphalerons of a new non-Standard Model gauge interaction can
cogenerate dark matter and baryonic matter. They can also wipe out
the symmetric component of the dark matter by a process of "pre-annihilation.
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...
Julien Carron
(University of Sussex, United Kingdom)
10/09/2015, 14:20
During the nonlinear evolution from Gaussian initial conditions, Fourier modes of the cosmological matter density field gradually develop statistical dependence. A precise understanding of this cosmic (co)variance is essential for the ultimate success of the ambitious upcoming wide-field surveys targeting cosmic acceleration or modified theories of gravity. I will discuss the dynamics of the...
Pablo Gonzalez
(Universidad de Chile, Chile)
10/09/2015, 14:40
We present a model of the gravitational field based on two symmetric tensors, $g_{\mu \nu}$ and $\tilde{g}_{\mu \nu}$. Besides, we have a new matter field given by $\tilde{\phi}_I = \tilde{\delta} \phi_I$, where $\phi_I$ are the original matter fields. We call them $\tilde{\delta}$ matter fields. This model, called $\tilde{\delta}$ Gravity, has excellent properties at the quantum level. It...
Toyokazu Sekiguchi
(University of Helsinki, Finland)
10/09/2015, 14:40
We consider decaying dark matter (DDM) as a resolution to the possible tension between cosmic microwave background (CMB) and weak lensing (WL) based determinations of the amplitude of matter fluctuations, $\sigma_8$. We perform N-body simulations in a model where dark matter decays into dark radiation and develop an accurate fitting formula for the non-linear matter power spectrum, which...
Sang Hui Im
(Institute for Basic Science, Republic of Korea)
10/09/2015, 14:40
We propose a new mechanism to suppress the axion isocurvature perturbation,
while producing the right amount of axion dark matter, within the framework of
supersymmetric axion models with the axion scale induced by supersymmetry breaking.
The mechanism involves an intermediate phase transition to generate the Higgs
mu-parameter, before which the weak scale is comparable to the axion scale
and...
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...
Alkistis Pourtsidou
(University of Portsmouth, United Kingdom)
10/09/2015, 15:00
21cm cosmology is a new and exciting area of research with
a great deal of potential. We have now entered an era of precision cosmology, but almost all of the information used to achieve this precision has come from the CMB at redshift z ~ 1100 or from galaxy surveys below z ~ 1.5. Using observations of the redshifted 21 cm line of atomic hydrogen (HI) we can look at previously unexplored...
Vanessa Smer Barreto
(University of Edinburgh, United Kingdom)
10/09/2015, 15:00
Two models of the hybrid metric-Palatini theory of gravitation are introduced. Their background evolution is explored, showing explicitly that one recovers standard General Relativity with an effective Cosmological Constant at late times. This happens because the Palatini Ricci scalar evolves towards and asymptotically settles at the minimum of its effective potential during cosmological...
Neil Barrie
(University of Sydney, Australia)
10/09/2015, 15:00
We propose a simple mechanism for generating ordinary luminous and dark matter during cosmic inflation. This scenario involves an extension of the Standard Model through the introduction of a dark matter candidate/s and an anomalous U(1)_X gauge group. The general framework developed is found to be able to replicate both the observed matter-antimatter asymmetry and the dark-to-visible matter...
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...
Mike Hewitt
(Canterbury Christ Church University, United Kingdom)
10/09/2015, 15:20
The successful $\Lambda CDM$ cosmological model requires a small but nonzero $\Lambda$ which appears to have an unnaturally small value compared to the supersymmetry breaking scale, typically $O(10^{-60}) m_{3/2}^4$ for $m_{3/2} \sim 10 TeV$. We explore the possibility of solving this naturalness problem in a special class of no-scale supergravity models which arise from a supersymmetric...
Krzysztof Turzynski
(University of Warsaw, Poland)
10/09/2015, 15:20
We revisit the calculation of the abundance of the supersymmetric dark matter particles: neutralino, gravitino, singlino and axino, taking into account the possibility that the reheating temperature of the Universe after inflation can be of the order of the electroweak scale or even lower. This leads to dramatic departures of predictions from the usually considered case of high reheating...
Stephen Feeney
(Imperial College London, United Kingdom)
10/09/2015, 15:20
Recent results from the BICEP2, Keck Array and Planck collaborations demonstrate that Galactic foregrounds are an unavoidable obstacle in the search for evidence of inflationary gravitational waves in the cosmic microwave background (CMB) polarisation. Beyond the foregrounds, the effects of lensing by intervening large-scale structure further obscure all but the strongest inflationary signals...
Shuntaro Mizuno
(Waseda University, Japan)
10/09/2015, 16:10
We investigate the effect of equilateral-type primordial trispectrum on the halo/galaxy bispectrum.
We consider three types of equilateral primordial trispectra which are generated by quartic operators naturally appearing
in the effective field theory of inflation and can be characterized by three nonlinearity parameters,
$g_{\rm NL} ^{\dot{\sigma}^4}$, $g_{\rm NL} ^{\dot{\sigma}^2 (\partial...
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...
Adam Christopherson
(University of Florida, United States)
10/09/2015, 16:10
Dark matter is a crucial ingredient of the standard cosmological model, making up over 80% of the total matter in the Universe. Although observational evidence strongly favors the existence of dark matter, we are yet to physically detect a particle, despite many attempts to do so. In order to model the dynamics of structure formation with dark matter one uses Newtonian physics, where we are...
Ilia Musco
(LUTH - Observatoire de Paris, France)
10/09/2015, 16:10
It has been suggested that a scalar field φ non-minimally coupled to matter could be responsible for the observed accelerated expansion of the Universe. However, the fact that we are able to measure its effect only on cosmological scales but not on local ones, such as that of our solar system, might be the consequence of a screening mechanism. This is the essence of the Chameleon model....
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...
Jinn-Ouk Gong
(Asia Pacific Center for Theoretical Physics, Republic of Korea)
10/09/2015, 16:30
We investigate the effects of homogeneous general dark energy on the non-linear matter perturbation in fully general relativistic context. The equation for the density contrast contains even at linear order new contributions which are non-zero for general dark energy. Taking into account the next-to-leading corrections, the total power spectrum with general dark energy deviates from the...
Shinta Kasuya
(Kanagawa University, Japan)
10/09/2015, 16:30
We study Q-ball dark matter in gauge-mediated supersymmetry breaking, and seek the
possibility of detection in the IceCube experiment. We find that the Q balls would be the dark matter in
the parameter region different from that for gravitino dark matter. In particular, the Q ball is a good
dark matter candidate for low reheating temperature, which may be suitable for the...
Ali Nayeri
(Chapman University, United States)
10/09/2015, 16:30
Some years ago in the context of a mechanism that thermally generates the primordial perturbations through a Hagedorn phase of string cosmology (Nayeri-Brandenberger-Vafa (NBV) setup) a blue tensor tilt with an induced and complimentary red tilt to the scalar spectrum, with a naturally large tensor to scalar ratio that relates to both, was found. One of the shortcomings of this setup, however,...
Kenji Kadota
(Institute for Basic Science, Republic of Korea)
10/09/2015, 16:50
The future prospects for the constraints on the particle dark matter from the 21cm signals will be presented.
The effects of the dark matter interactions with the baryons on the 21 cm observables will be discussed, along with its comparison with the complementary bounds from the direct dark matter search experiments.
I will also discuss the 21 cm bounds on the ultra light dark matter which...
Pawel Bielewicz
(SISSA, Italy)
10/09/2015, 16:50
We present the first measurement of the correlation between the map of the CMB lensing potential derived from the Planck mission data and high-redshift galaxies detected by the Herschel-ATLAS (H-ATLAS) survey. This galaxy catalogue is the highest redshift sample for which the correlation between Planck CMB lensing and tracers of large-scale structure has been investigated so far. We perform a...
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...
Purnendu Karmakar
(Universita degli Studi di Padova, Italy)
10/09/2015, 16:50
P. Karmakar, in collaboration with: F. Arroja, N. Bartolo and S. Matarrese
(arXiv:1506.08575).
We show that very general scalar-tensor theories of gravity (including, e.g., Horndeski models) are generically invariant under disformal transformations. However there is a special subset, when the transformation is not invertible, that yields new equations of motion which are a generalization...
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.
Matteo Tellarini
(ICG, Portsmouth, United Kingdom)
10/09/2015, 17:10
Primordial non-Gaussianity can lead to a scale-dependent bias in the density of collapsed halos relative to the underlying matter density. The galaxy power spectrum already provides constraints on local-type primordial non-Gaussianity complementary those from the cosmic microwave background (CMB), while the bispectrum contains additional shape information and has the potential to outperform...
Thorsten Battefeld
(University of Goettingen, Germany)
10/09/2015, 17:10
Moduli spaces in string theory, often dubbed Landscapes, are usually of high dimensionality and feature a complicated potential. Is multi-field inflation on such landscapes consistent with current observations? Modeling such landscapes by random potentials offers the opportunity to asses generic features of inflation. Random matrix theory provides a tool (complementing numerical experiments)...
Alexey Boyarsky
(Leiden University, Netherlands)
10/09/2015, 17:10
I will review model-independent bounds on the properties of DM particles and the current state of searches
for the signatures of decayingh super-weakly intercating DM particles in astrophysical data.
Thomas Tram
(ICG Portsmouth University, United Kingdom)
10/09/2015, 17:30
The existence of Dark Matter has been confirmed by many different cosmological probes including observations of the Cosmic Microwave Background (CMB) and the Large Scale Structure (LSS) of the Universe. But what else can we learn about the nature of Dark Matter from CMB and LSS data? One parameter of interest is the decay rate of Dark Matter. Even though Dark Matter must be stable on...
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,...
Wessel Valkenburg
(Leiden University, Netherlands)
10/09/2015, 17:30
I will present a novel description for setting initial particle displacements and field values under arbitrary metric theories of gravity, for perfect and imperfect fluids with arbitrary characteristics. We extend the Zel'dovich Approximation to nontrivial theories of gravity, and show how scale dependence implies curved particle paths, even in the entirely linear regime of perturbations....
Giovanni Marozzi
(Universite de Geneve, Switzerland)
10/09/2015, 17:30
In this talk, I will present the evaluation of the galaxy number counts to second order in cosmological perturbation theory in the Poisson gauge. The calculation is performed using an innovative approach based on the recently proposed ”geodesic light-cone” gauge, which allows us to determine the number counts in a purely geometric way. To conclude, I will present the numerical results for the...
Mateusz Duch
(University of Warsaw, Poland)
10/09/2015, 17:50
We explored an extension of the Standard Model by an additional U(1) gauge group and a complex scalar interacting through the Higgs portal. As the scalar is charged under this gauge factor, this simple model supplies a vector dark matter candidate satisfying the observed relic abundance and limits from direct dark matter searches at LUX and XENON. An additional Higgs-like state, that may be...
Mathew Hull
(University of Portsmouth, United Kingdom)
10/09/2015, 17:50
Vectors with ghost-free derivative self-interactions have been shown to have interesting cosmological applications. They form a ghost-free extension of the Proca theory that has a Galileonic longitudinal mode and can be generated naturally via a Higgs mechanism. In this talk I will discuss recent results on the covariantisation of these models and their relation to general ghost-free...
Yohei Ema
(The University of Tokyo, Japan)
10/09/2015, 17:50
Yuichiro Tada
(Kavli IPMU, Japan)
10/09/2015, 17:50
Primordial black holes (PBHs) are theoretical black holes which can be formed during the radiation dominant era through the gravitational collapse of radiational overdensities. It has been well known that in the context of the structure formation in our Universe such collapsed objects, e.g., halos/galaxies, could be considered as bias tracers of underlying matter fluctuations and the...
Dragan Huterer
(University of Michigan, United States)
11/09/2015, 09:00
Jun'ichi Yokoyama
(RESCEU The University of Tokyo, Japan)
11/09/2015, 09:35
Fernando Quevedo
(The Abdus Salam International Centre for Theoretical Physics, Italy)
11/09/2015, 10:40
Livia Soffi
(Cornell University, United States)
11/09/2015, 11:15
Carlos Martins
(CAUP, Portugal)
11/09/2015, 11:50
Leszek Roszkowski
(National Centre for Nuclear Research, Poland)
11/09/2015, 12:25
Cornelius Rampf
(Portsmouth University, United Kingdom)
11/09/2015, 14:00
Analytical methods have been fairly successful to understand the Newtonian regime of cosmological structure formation. Such methods are usually based on standard perturbation techniques which are however only approximative tools, and therefore might be not able to achieve the required accuracy to confront the theory with data from upcoming surveys. In this talk we show that it is actually...
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...
Christian Reichardt
(University of Melbourne, Australia)
11/09/2015, 14:20
Measurements of the polarization of the cosmic microwave background (CMB) are rapidly becoming an important tool to test the standard model of cosmology. In particular, searches for the faint CMB B-mode signals offer the prospect of detecting inflationary gravitational waves on large angular scales and mapping out the large scale distribution of matter in the Universe through CMB lensing on...
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...
Pawel Klimasara
(University of Silesia, Poland)
11/09/2015, 14:40
We discuss the recently proposed model where LSS of spacetime is parametrized by the usual real line R, while at small (QM) scales space is parametrized by real numbers from RM. Here RM is the real line in certain model M of formal Zermelo-Fraenkel set theory. When passing from RM to R the set-theoretic forcing on measure algebra of R3 has to be performed. The "old" set of reals RM is merely a...
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...
Viraj Sanghai
(Queen Mary University of London, United Kingdom)
11/09/2015, 15:00
We construct a framework to probe the effect of non-linear structure formation on the large-scale expansion of the universe. We take a bottom-up approach to cosmological modelling by splitting up our universe into cells. The matter content within each cell is described by the post-Newtonian formalism. We assume that most of the cell is in the vicinity of weak gravitational fields, so that it...
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...
Jacques Wagstaff
(Hamburg University, Germany)
11/09/2015, 15:20
We calculate the CMB spectral distortions due to the decay of causally generated magnetic fields at the electroweak and QCD phase transitions. We show that the decay of non-helical magnetic fields generated at either the electroweak or QCD scale produce μ and y-type distortions below 10^−8 which are probably not detectable by a future PIXIE-like experiment. We show that magnetic fields...
