# The 4th UniverseNet School - Frontiers of Particle Cosmology

Europe/Rome
Lecce, Università del Salento

#### Lecce, Università del Salento

Via Michele De Pietro, 12 I-73100 Lecce (LE)
Description
UniverseNet is supported by the European Community's Sixth Framework Programme (contract n. MRTN-CT-2006-035863). This network brings together the major European theoretical physics groups whose research involve cosmology and its relationship with particle physics. The UniverseNet Schools provide training for postgraduate students and postdoctoral researchers. After the successful past schools, the 4rd UniverseNet school will be held in Officine Cantelmo of the Università del Salento in Lecce, Italy. The program, from Monday to Friday, will consist on lectures and discussions. There will also be short talks on current research topics. On Saturday morning there will be the annual meeting of the network open to network members only. All members of UniverseNet are invited to attend with support to be provided by their respective teams - please apply to your Scientist-in-Charge to arrange this and having done so please fill in the registration form and the accommodation request form. We also welcome other researchers who wish to attend the school - however we reserve the right to decline applications for operational reasons. Graduate students (who do not belong to UniverseNet) must ask their research supervisors to email a letter of support to the address univnet10@le.infn.it
Participants
• Abhilash Mishra
• Aleksandra Drozd
• Alfredo Urbano
• Ana Valente
• Andrzej Hryczuk
• antonio enea romano
• Antonio Mariano
• Antonio Masiero
• Antonio Quintavalle
• Antonio Racioppi
• arindam chatterjee
• Arman Shafieloo
• Arnaud de Lavallaz
• Beata Malec
• Bogna Kubik
• Bouillot Vincent
• Chiara Caprini
• Christel Smith
• Christopher McCabe
• Claudio Corianò
• Cliff Burgess
• Daniel Albornoz
• Daniel Thomas
• Daniele Gaggero
• Daniele Montanino
• Daniele Vetrugno
• David Lyth
• David Marsh
• David Mulryne
• Denis Comelli
• Dorota Sokolowska
• Eligio Lisi
• Elise Jennings
• Emeline CLUZEL
• Fabio Masillo
• Filippo Sala
• Finn Ravndal
• Francesca Doddato
• Francisco Pedro
• Gabrijela Zaharijas
• George Lazarides
• George Leontaris
• German Arturo Gomez Vargas
• Giovanni Italo Martone
• Gregory Sculthorpe
• Grigoris Panotopoulos
• Ioannis Dalianis
• Ioannis Rizos
• Ippocratis Saltas
• Jacques Wagstaff
• Jan Hamann
• jeremie llodra-perez
• Jesus M Moreno
• Joel Weller
• Johannes Noller
• John McDonald
• Jonathan Frazer
• Jose Miguel No
• José Fonseca
• Julien Lesgourgues
• Kari Enqvist
• Kazunori Kohri
• KONSTANTINOS DIMOPOULOS
• Kyriakos Tamvakis
• Leandros Perivolaropoulos
• LESLAW RACHWAL
• Luca Amendola
• Luca Panizzi
• Luigi Delle Rose
• Luigi Manni
• Luke Barclay
• Mafalda Dias
• Manuel Drees
• Marcello Musso
• Marcin Świerczek
• Marco CIRELLI
• Mariano Quiros
• Matthew McCullough
• Michael Gustafsson
• Michal Artymowski
• Michal Deak
• Michela D'Onofrio
• Miguel Pato
• Mindaugas Karciauskas
• Minos Axenides
• Mirko Serino
• Muntazim Shah
• Nhu Le Nguyen
• Nicola Orlando
• Nicolao Fornengo
• Nikolaos Brouzakis
• Nikolaos MAVROMATOS
• Nikolaos Pappas
• Olli Taanila
• Paolo Ciafaloni
• Paolo Panci
• Pawel Pacholek
• Philip Stephens
• Philipp Mertsch
• Pierre Binetruy
• PIERRE SALATI
• Poul Damgaard
• Riccardo Barbieri
• Rizwan Shahid khan
• Robert OLivares Morales
• Roberta Armillis
• Rose Lerner
• Salah Eddine Boudelal
• Sander Mooij
• Sang-gyu Byun
• Savvas Nesseris
• shankar dayal pathak
• Shaun Hotchkiss
• sheng li
• Stefano Orani
• Subir Sarkar
• Tim Yeomans
• Tobias Hofbaur
• Tomasz Jelinski
• Tuukka Meriniemi
• Victor Vera
• Vittoria Demozzi
• Ylenia Maruccia
• Zygmunt Lalak
Support
• Monday, 13 September
• 09:00 10:00
Riccardo Barbieri (The Standard Model and beyond I)
• 10:00 10:15
mini break 15m
• 10:15 11:15
Andrew Jaffe (Standard cosmology and the CMB I)
• 11:15 11:45
Coffee-break 30m
• 11:45 12:45
Kazunori Kohri (Big Bang nucleosynthesis & new physics)
• 12:45 14:30
Lunch break 1h 45m
• 14:30 16:00
6 talks (Chair: Athanasios LAHANAS)
• 14:30
Mr. MCCULLOUGH, Matthew (University of Oxford): The Goldstini Variations 15m
• 14:45
Mr. PAPPAS, Nikolaos (University of Ioannina): Emission of Massive Scalar Fields by a Higher-Dimensional Rotating Black-Hole 15m
We perform a comprehensive study of the emission of massive scalar fields by a higherdimensional, simply rotating black hole both in the bulk and on the brane. We derive approximate, analytic results as well as exact numerical ones for the absorption probability, and demonstrate that the two sets agree very well in the low and intermediate-energy regime for scalar fields with mass m 1 TeV in the bulk and m 0.5 TeV on the brane. The numerical values of the absorption probability are then used to derive the Hawking radiation power emission spectra in terms of the number of extra dimensions, angular-momentum of the black hole and mass of the emitted field. We compute the total emissivities in the bulk and on the brane, and demonstrate that, although the brane channel remains the dominant one, the bulk-over-brane energy ratio is considerably increased (up to 33%) when the mass of the emitted field is taken into account.
• 15:00
Mr. NO, Jose Miguel Postdoc (CEA Saclay): Bubble growth and energy budget in cosmological first order phase transitions 15m
A cosmological first order phase transition can lead to many interesting phenomena, such as electroweak baryogenesis, primordial magnetic fields, or the production of a stochastic background of gravitational waves. All of them rely on the phase transition proceeding through the nucleation and subsequent expansion of bubbles, and apart from the quantities that describe the phase transition itself, there are other quantities that become relevant for describing these phenomena, such as the velocity of the expanding bubbles or the efficiency coefficients for converting the available free energy of the Higgs field into fluid bulk motion, thermal energy and gradient/kinetic energy of the Higgs field. Here We review the hydrodynamic treatment used to describe the fluid motion once bubbles start growing, and go on to obtain the energy conversion efficiency coefficients. We also study the recent possibility of having continuosly accelerating (runaway) bubbles, and how their existence modifies previous studies on bubble growth.
• 15:15
Dr. SMITH, Christel (Arizona State University): Investigating the Synthesis of the Primordial Lithium Isotopes with New Nuclear and Neutrino Physics 15m
The discrepancy between the primordial 7Li predicted abundance and the observed abundance in metal poor halo stars has been a longstanding problem. This problem may in fact be coupled with recent observational suggestions that there could be 2-3 orders of magnitude more 6Li than Big Bang Nucleosynthesis (BBN) calculations predict. We explore these issues by developing a more comprehensive nuclear reaction network. Some of the nuclear reactions incorporated have not previously been included in BBN calculations and few are well measured in the laboratory. We also discuss the effect of lepton captures on nuclei in BBN and present some calculations.
• 15:30
Ms. SOKOLOWSKA, Dorota (ITP Warsaw) Inert Model and the evolution of the Universe 15m
We consider evolution of the Universe after EWSB leading to the present Inert phase, containing a SM-like Higgs boson and scalar dark particles among them a Dark Matter candidate. In particular we address the question, if there is a possibility to have a sequence of the phase transitions instead of a single one leading directly from EW symmeric phase to the Inert one.
• 15:45
Mr. VARDANYAN, Mihran (University of Oxford): How big is the Universe? 15m
One of the most important questions of cosmology is to determine whether the Universe is spatially finite or infinite. We use Bayesian model averaging to derive new constraints on the minimum size of the Universe. Our procedure accounts for the model uncertainty between the three different possibilities for the geometry of the Universe in the context of a Friedmann-Robertson-Walker metric (flat, open or closed) as well as for the possibility of an evolving dark energy component. We use recent cosmological observations to set tighter limits on the curvature parameter. I'll report our results from most conservative prior choice as well as discuss the dependency of our results on the choice of priors.
• 16:00 16:30
Coffee break 30m
• 16:30 18:00
• 16:30
Mr. ALBORNOZ, Daniel (LAPTH Annecy): Lightest neutralinos in the (N)MSSM 15m
Recently direct detection experiments claim Dark Matter like events. If they were caused by WIMPs indeed, then they point towards rather light (a few to 50 GeV, depending on experiments) Dark Matter particles. We review the plausibility of light neutralinos with relatively large elastic scattering cross sections in the Minimal and Next-to-Minimal Supersymmetric Standard Models (MSSM & NMSSM). Applying cosmological, new particle searches, B-physics and electroweak precision constraints, we explore the parameter spaces using a Monte Carlo Markov Chain. We then check whether there are any points providing neutralinos with the suited cross section and mass for direct detection experiments. We take into account the no-signal claim of Xenon100 and TeVatron constraints to the Higgs sector to further analyse those points. While MSSM fails to provide an interesting candidate, the NMSSM can overcome all constraints and produce neutralinos in the region of interest.
• 16:45
Dr. FRANDSEN, Mads Toudal (University of Oxford): Asymmetric dark matter 15m
Cold dark matter particles with an intrinsic matter-antimatter asymmetry do not annihilate after gravitational capture by the Sun and can aect its interior structure. The rate of capture is exponentially enhanced when such particles have self-interactions of the right order to explain structure formation on galactic scales. A dark baryon' of mass 5 GeV is a natural candidate and has the required relic abundance if its asymmetry is similar to that of ordinary baryons. We show that such particles can solve the solar composition problem'. The predicted small decrease in the low energy neutrino uxes may be measurable by the Borexino and SNO+ experiments.
• 17:00
Mr. MCCABE, Christopher (University of Oxford): Neutrino-Flavoured Sneutrino Dark Matter 15m
A simple theory of supersymmetric dark matter (DM) naturally linked to neutrino flavour physics is studied. The DM sector comprises a spectrum of mixed lhd- rhd sneutrino states where both the sneutrino flavour structure and mass splittings are determined by the associated neutrino masses and mixings.
• 17:15
Mr. PATO, Miguel (Padova University): Systematic uncertainties in the determination of the local dark matter density 15m
We quantify systematic uncertainties associated with the determination of the local dark matter density from dynamical measurements in our Galaxy. Using very recent high-resolution numerical simulations of Milky Way like galaxies, we study the effect of baryonic physics on dark matter halos and how this can bias the inference of the dark matter density in our neighbourhood. Such piece of information is crucial in interpreting the results from direct detection dark matter experiments.
• 17:30
Dr. RACIOPPI, Antonio (NICPB Tallin): Matter parity, scalar dark matter and LHC 15m
We extend the concept of matter parity P_M=(-1)^{3(B-L)} to non-supersymmetric theories and argue that P_M is the natural explanation to the existence of Dark Matter (DM) of the Universe. If the underlying Grand Unified Theory gauge group is SO(10), then non-supersymmetric scalar DM must be contained in a scalar 16 representation and the unique low energy DM candidates are a P_M-odd complex scalar singlet S and an inert scalar doublet H_2. We construct a minimal matter parity DM model where DM is made by a combination of the scalar singlet S and the inert doublet H_2 and study its phenomenology at LHC. We focus on the lightest dark scalar S_{DM}, the next-to-lightest dark scalar S_{NL} and the charged Higgs H^+. S_{NL} is predicted to be long-lived, providing distinctive experimental signatures of displaced vertex of two leptons or jets plus missing transverse energy. Also H^+ can have a macroscopic decay length in a notable region in the parameter space.
• 17:45
Mr. URBANO, Alfredo (Salento University): Electroweak corrections to Dark Matter indirect detection 15m
Considering Dark Matter (DM) annihilations and decays into Standard Model particles, we study in a model independent way the role of electroweak radiative corrections. Since electroweak interactions link all SM particles, in fact, all stable ones (including antiprotons and independently from the primary particle initially considered) will be present in the final spectrum. Results show very interesting features for TeV scale DM concerning final stable positrons, antiprotons and photons. Both leptonic and bosonic annihilation channels are qualitatively affected and electroweak corrections alter energy spectra for one order of magnitude or more.
• Tuesday, 14 September
• 09:00 10:00
Riccardo Barbieri (The Standard Model and beyond II)
• 10:00 10:15
mini break 15m
• 10:15 11:15
Andrew Jaffe (Standard cosmology and the CMB II)
• 11:15 11:45
Coffee break 30m
• 11:45 12:45
Nicolao Fornengo (Dark matter: direct detection)
• 12:45 14:30
Lunch break 1h 45m
• 14:30 16:00
6 talks (Chair: Leandros PERIVOLAROPOULOS)
• 14:30
Mr. DEAK, Michal (IFT Madrid): Exclusive Higgs production consistent with MSSM baryogenesis 15m
• 14:45
Mr. DALIANIS, Ioannis (ITP Warsaw): Cosmological Aspects of SUSY Breaking 15m
Cosmological considerations of theories which promote a (false) metastable vacuum as the phenomenological viable one. Demonstration that quantum corrections and weakly coupled messenger-SUSY breaking sector can make the metastable vacuum, during thermal evolution, attractive. Remarks on gaugino and sfermion masses in these models. Also, inflationary dynamics and SUSY breaking - a different perspective.
• 15:00
Mr. MOOIJ, Sander (NIKHEF Amsterdam): Moduli Stabilization in SUGRA Hybrid Inflation 15m
We study the supergravity hybrid inflation model of (arXiv:0902.2934 ) in the presence of a modulus field. The eta-problem is solved by a shift symmetry for the inflaton, which protects the inflaton mass even in the presence of the modulus field. Inflation is (nearly) unaffected by moduli stabilization, provided the scale of supersymmetry breaking in the post-inflation vacuum is small. Therefore the model has the nice phenomenology that it combines low scale supersymmetry breaking with high scale (grand unification scale) inflation.
• 15:15
Mr. STEPHENS, Philip (Lancaster University): Improving Inflection Point inflation 15m
I present some work on alleviating the fine tuning problem in inflection point inflation.
• 15:30
Mr. TAANILA, Olli (Helsinki Institute of Physics): A TeV-mass Curvaton 15m
We consider a curvaton with a mass of 1 TeV and show that the constraints are not consistent with a purely quadratic potential. We then show that the only self-interaction consistent with all the constraints is of the form V_int = sigma^8/M^4. We also compute the values of non-Gaussianity parameters f_NL and g_NL.
• 15:45
Mr. WAGSTAFF, Jacques (Lancaster University): A Compelling Vector Curvaton Model without Instabilities 15m
A vector curvaton model with a Maxwell kinetic term and varying kinetic function and mass during inflation is studied. It is shown that, if light until the end of inflation, the vector field can generate statistical anisotropy in the curvature perturbation spectrum and bispectrum, with the latter being predominantly anisotropic. If by the end of inflation the vector field becomes heavy, then particle production is isotropic and the vector curvaton can alone generate the curvature perturbation. The model does not suffer from instabilities such as ghosts and is the only concrete model, to date, which can produce the curvature perturbation without direct involvement of fundamental scalar fields.
• 16:00 16:30
Coffee break 30m
• 16:30 18:00
6 talks (Chair: Pierre SALATI)
• 16:30
Mr. GAGGERO, Daniele (INFN Pisa): Combined interpretation of recently measured electron, positron and antiproton spectra 15m
We present some models which try to interpret the recently published results on electron+positron spectrum by Fermi-LAT collaboration and on positron fraction by PAMELA in terms of a combination of a Galactic component plus an extra primary source of electron+positron pairs of astrophysical origin. We adopt several diffusion setups, whose parameters are constrained by recent CREAM B/C data and PAMELA antiproton data, and discuss the impact of varying the diffusion setup on the interpretation of electron and positron data. Our analysis is performed both with GALPROP and DRAGON numerical packages. We also discuss the implications of our models for anisotropy measurements of CR electron flux.
• 16:45
Dr. GUSTAFSSON, Michael (INFN Padova): Constraining dark matter properties from gamma-ray measurements 15m
I will try to highlight one or few of the Fermi collaboration's published results on constraining dark matter properties.
• 17:00
Mr. HRYCZUK, Andrzej (SISSA Trieste): Sommerfeld enhancements in the MSSM 15m
In this talk I will describe the Sommerfeld effect arising due to gauge and Higgs boson exchange within the full MSSM. I will present and discuss a general method of computing this effect and numerical results showing its relevance for the relic density of general neutralino dark matter.
• 17:15
Mr. MERTSCH, Philipp (University of Oxford): Systematic effects in the extraction of the 'WMAP haze' 15m
The extraction of a 'haze' from the WMAP microwave skymaps is based on subtraction of known foregrounds, viz. free-free (bremsstrahlung), thermal dust and synchrotron, each traced by other skymaps. While the 408 MHz Effelsberg survey is used for the synchrotron template, the WMAP bands are at tens of GHz where the spatial distribution of the radiating cosmic ray electrons ought to be quite different because of the energy-dependence of their diffusion in the Galaxy. The systematic uncertainty this introduces in the residual skymap is comparable to the claimed haze and can, for certain source distributions, even have a similar morphology and spectrum. Hence caution must be exercised in interpreting the haze as a signature of dark matter annihilation in the Galactic centre.
• 17:30
Mr. PANCI, Paolo (University of L'Aquila & Paris 7 & CERN): Diffuse gamma Ray Constraints on Annihilating or Decaying DM after Fermi 15m
We consider the diffuse gamma ray data from FERMI first year observations and compare them to the gamma ray fluxes predicted by Dark Matter annihilation or decay, for different observational regions of the sky and a range of Dark Matter masses, annihilation/decay channels and Dark Matter galactic profiles. We find that the data exclude large regions of the Dark Matter parameter space not constrained otherwise. Also, we further constrain Dark Matter interpretations of the positrons PAMELA/FERMI spectral anomalies, both for annihilation and the decaying Dark Matter case: under very conservative assumptions, only models producing dominantly muons and assuming a cored Dark Matter galactic profile can fit the lepton data with masses around 2 TeV.
• 17:45
Dr. ZAHARIJAS, Gabrijela (CEA Saclay): Constraints on Dark Matter Annihilation from the Fermi-LAT Diffuse Gamma-Ray Measurement 15m
The diffuse measurement of the Fermi Large Area Telescope (LAT) can be a powerful tool in constraining the dark matter properties. In this talk, I will present constraints on dark matter models derived from the intensity and spectral shape of the Fermi-LAT Isotropic diffuse data. I will discuss the relation of the cosmological dark matter signal to the one coming from within our Galaxy, as well as preliminary dark matter constraints coming from the analysis of the Galactic diffuse data. Finally, I will comment on the benefits of complementarity between Fermi-LAT and ground-based Cerenkov observations to robustly constrain some particle physics models.
• Wednesday, 15 September
• 09:00 10:00
Marco Cirelli (Dark matter: indirect detection)
• 10:00 10:15
mini break 15m
• 10:15 11:15
Eligio Lisi (Neutrino physics and cosmology)
• 11:15 11:45
Coffee break 30m
• 11:45 13:00
3 Talks
• 11:45
LAZARIDES, George (Thessaloniki): Hybrid Inflation and Peccei-Quinn phase transition 25m
We consider an inflationary model based only on renormalizable superpotential terms in which a superheavy scale hybrid inflation is followed by a Peccei-Quinn (PQ) phase transition. We show that the field which triggers the PQ phase transition influences drastically the inflationary dynamics and that the Universe undergoes a secondary phase of reheating after the PQ phase transition. Confronting inflation with the current observational data we find that, for the central value of the spectral index, the GUT scale can assume its supersymmetric value for more or less natural values for the model parameters. On the other hand the final reheat temperature after the PQ phase transition turns out to be low enough to avoid the gravitino problem.
• 12:10
PERIVOLAROPOULOS, Leandros (Ioannina): Growth of Dark Energy Perturbations in Scalar-Tensor Cosmologies 25m
I compare the growth of dark energy and matter perturbations in scalar tensor cosmologies with the corresponding growth in minimally couple quintessence. An interesting amplification of dark energy perturbations will be discussed and other useful observational signatures will be pointed out.
• 12:35
SAKELLARIADOU, Mairi (London): NonCommutative Spectral Geometry as an approach to Unification 25m
• 13:00 14:30
Lunch break 1h 30m
• 14:30 20:15
Excursion followed by Conference Dinner
• Thursday, 16 September
• 09:00 10:00
Luca Amendola (Testing dark energy and alternatives I)
• 10:00 10:15
mini break 15m
• 10:15 11:15
Cliff Burgess (Inflation and fundamental physics I)
• 11:15 11:45
Coffee break 30m
• 11:45 12:45
Julien Lesgourgues (Statistical methods for cosmology)
• 12:45 14:30
Lunch break 1h 45m
• 14:30 16:00
6 Talks (Chair: Poul DAMGAARD)
• 14:30
Dr. BROUZAKIS, Nikolaos (IFAE Barcelona): Non-linear Matter Spectrum for a Variable Equation of State 15m
We study the growth of matter perturbations beyond the linear level in cosmologies in which the dark energy has a variable equation of state. The non-linear corrections result in shifts in the positions of the maximum, minima and nodes of the spectrum within the range of Baryon Acoustic Oscillations. These can be used in order to distinguish theories with different late-time variability of the equation of state.
• 14:45
Mr. DE LAVALLAZ, Arnaud (King's College London): Voids in LambdaCDM: Effects on Density Parameters 15m
We consider a Swiss-cheese model embedded in a LambdaCDM universe in order to study the effects that voids might have on conclusions about dark energy. Testing various geometrical configurations, we want to analyse how voids could affect the values of Omega_m and Omega_{Lambda}.
• 15:00
Ms. JENNINGS, Elise (Durham University): Predictions for large-scale structure in future galaxy redshift surveys 15m
Forthcoming galaxy redshift surveys will make high precision measurements of the clustering of galaxies on scales in excess of 100/h Mpc. In particular, the quantification of the distortion of clustering due to the peculiar motions of galaxies and the scale of characteristic features in the galaxy distribution have been proposed as tests of the cosmic acceleration. To obtain robust constraints on dark energy, we need to understand any systematic effects which cause deviations from linear perturbation theory which is commonly appplied on these scales. I will present the predictions for BAO and redshift space distortions using large volume N-body simulations which demonstrate that linear theory is not sufficient to model future surveys. These calculations include the first consistent simulations of quintessence dark energy models. Some of these models cannot be distinguished from LCDM using BAO alone. I will also describe a procedure for analysing redshift-space distortions in a range of cosmologies which is a major improvement over linear theory.
• 15:15
Dr. MUSSO, Marcello (ICTP Trieste): Improved excursion set formalism for the halo mass function 15m
• 15:30
Dr. PARANJAPE, Aseem (ICTP Trieste): Improved calculations of the non-Gaussian mass functions for halos and voids (A) 15m
• 15:45
Mr. ROMANO, Antonio Enea (National Taiwan University): Dark energy or large scale inhomogeneities? 15m
As an alternative to dark energy it has been suggested that we may be at the center of an inhomogeneous isotropic universe described by a Lemaitre-Tolman-Bondi (LTB) solution of Einstein's field equations. In order to test this hypothesis we calculate the general analytical formula to fifth order for the redshift spherical shell mass. Using the same analytical method we write the metric in the light-cone by introducing a gauge invariant quantity G(z) which together with the luminosity distance DL(z) completely determine the light-cone geometry of a LTB model. Finally we combine these results with the luminosity distance formulae and show how $\LambdaCDM$ models cannot be mimicked by smooth large scale inhomogeneities, independently of the value of the cosmological constant.
• 16:00 16:30
Coffee break 30m
• 16:30 18:00
6 talks (Chair: Minos AXENIDES)
• 16:30
Dr. HAMANN, Jan (Aarhus University): Supernova anisotropies 15m
Measurements of the luminosity distances of type Ia supernovae can be used to reconstruct the local radial velocity field. I will introduce a method to extract the anisotropy spectrum from supernova data, discuss its usefulness as a cosmological probe, present the current state of affairs and give an outlook on the potential of upcoming surveys.
• 16:45
Mr. NADATHUR, Seshadri (University of Oxford): Confronting inhomogeneous cosmologies with CMB data 15m
Recently there has been much interest in inhomogeneous cosmological models, especially Gpc scale voids described by an LTB metric, as a means to explain the supernovae Hubble diagram without the need for a cosmological constant. I will discuss these models and attempts to use the WMAP CMB angular power spectrum data to constrain them, especially in the context of alternative models of inflation.
• 17:00
Dr. NESSERIS, Savvas (NBIA Copenhagen): A model-independent null test on the cosmological constant 15m
We use the Om statistic and the Genetic Algorithms (GA) in order to derive a null test on the spatially flat cosmological constant model ?CDM. This is done in two steps: first, we apply the GA to the Constitution SNIa data in order to acquire a model independent reconstruction of the expansion history of the Universe H(z) and second, we use the reconstructed H(z) in conjunction with the Om statistic, which is constant only for the ?CDM model, to derive our constraints. We find that while ?CDM is consistent with the data at the 2? level, some deviations from ?CDM model at low redshifts seems to be mildly preferred.
• 17:15
Dr. MALEC, Beata (Copernicus Center, Cracow): Cosmic Equation of state from Strong Gravitational Lensing Systems 15m
Accelerating expansion of the Universe is a great challenge for both physics and cosmology. In light of lacking the convincing theoretical explanation, an effective description of this phenomenon in terms of a cosmic equation of state turns out useful. The strength of modern cosmology lies in consistency across independent, often unrelated pieces of evidence. Therefore, every alternative method of restricting the cosmic equation of state is important. Strongly gravitationally lensed quasar-galaxy systems create such a new opportunity by combining stellar kinematics (central velocity dispersion measurements) with lensing geometry (Einstein radius determination form position of images). In this talk we present such a method applied to a combined data sets from Sloan Lens ACS and Lens Structure and Dynamics surveys of gravitational lenses. As a result we obtain the cosmic equation of state parameters, which generally agree with results already known in the literature. This demonstrates that the method can be further used on larger samples obtained in the future. Independently noticed systematic deviation between fits done on standard candles and standard rulers is revealed in our findings. We also identify an important selection effect crucial to our method associated with the geometric configuration of the lensing system along line of sight, which may have consequences for sample construction from the future lensing surveys.
• 17:30
Dr. SHAFIELOO, Arman (University of Oxford): Problems of Reconstructing Dark Energy 15m
• 17:45
Mr. MARSH, David (University of Oxford): Cosmology and the String Axiverse 15m
It was noted in arXiv:0905.4720v2 [hep-th] that as a general feature "String theory suggests the simultaneous presence of many ultralight axions, possibly populating each decade of mass down to the Hubble scale 10-33eV". Axion like particles (ALPs) with masses of between $m=10^{-33}\mathbf{eV}$ and m=10^{-22}\mathbf{eV}$can affect the growth of structure in the Universe through the matter power pectrum. We compute these effects and present models for how they depend on the mass and fraction of the critical density in one ultra light ALP. Finally we briefly discuss possible observations. • Friday, 17 September • 09:00 10:00 Luca Amendola (Testing dark energy and alternatives II) • 10:00 10:15 mini break 15m • 10:15 11:15 Cliff Burgess (Inflation and fundamental physics II) • 11:15 11:45 Coffee break 30m • 11:45 12:45 Massimo Inguscio (Quantum simulation with ultra-cold atoms) • 12:45 14:30 Lunch break 1h 45m • 14:30 16:00 6 talks (Chair: Nikolaos MAVROMATOS) • 14:30 Mr. ARTYMOWSKI, Michal (IFT Warsaw): Loop Quantum Cosmology with vector fields 15m In the context of the loop quantum cosmology we have analyzed the evolution of the Bianchi I model in the presence of vector fields. The existence of the quantum of length changes visibly the evolution of the scale factors around the Planck scale. The finite maximal energy density epears even in the limit of vector field domination, which gives an efect of the classicall Big Bounce. In this talk I will analyze in some detail the LQC Bianchi I model with two scale factors and with a massless vector field, massive vector field, massive vector and scalar fields, and with a massive vector field with the mass term from the Higgs mechanism. All of those scenarios offer a physical source of the anisotropic expansion in Bianchi I model. • 14:45 Mr. BARCLAY, Luke (Durham University): Holographic Superconductors in Gauss-Bonnet Gravity 15m The concept of the holographic superconductor provides an exciting and novel way of investigating high temperature superconductivity via the study of black hole physics. In this talk I will discuss recent work done by myself and collaborators in which we studied fully back-reacting, holographic superconductors in Gauss-Bonnet gravity. First, I will give a brief introduction to the subject. I will then discuss our findings regarding the effect of the Gauss-Bonnet terms on the superconductor. • 15:00 Ms. CLUZEL, Emeline (CEA Saclay): Brane Bremsstrahlung in DBI Inflation 15m We consider the effect of trapped branes on the evolution of a test brane whose motion generates DBI inflation along a warped throat. The coupling between the inflationary brane and a trapped brane leads to the radiation of non-thermal particles on the trapped brane. We calculate the Gaussian spectrum of the radiated particles and their backreaction on the DBI motion of the inflationary brane. Radiation occurs for momenta lower than the speed of the test brane when crossing the trapped brane. The slowing down effect is either due to a parametric resonance when the interaction time is small compared to the Hubble time or a tachyonic resonance when the interaction time is large. In both cases the motion of the inflationary brane after the interaction is governed by a chameleonic potential,which tends to slow it down. We find that a single trapped brane can hardly slow down a DBI inflaton whose fluctuations lead to the Cosmic Microwave Background spectrum. A more drastic effect is obtained when the DBI brane encounters a tightly spaced stack of trapped branes. • 15:15 Mr. CONTILLO, Adriano (SISSA Trieste): Inflationary solutions in asymptotically safe f(R) theories 15m Power-law inflationary solutions obtained from Renormalization Group improvement of a class of f(R) theories recently studied in the context of asymptotic safety scenario are discussed. The higher-order gravity dynamics encode the dimensional scaling around the non-gaussian fixed point coming from the beta functions of a polynomial Lagrangian up to order n=8 in the scalar curvature R. By means of a dynamical identification of the energy scale of the renormalization group equation, it is then found that power-law inflation is a rather general prediction of RG improved cosmologies in this truncation. DeSitter solutions are also obtained in the case of pure gravity, and it is shown that they can be read as a limit case of the above mentioned power-law solutions. • 15:30 Mr. NOLLER, Johannes (Imperial College London): Bimetric structure formation: non-Gaussian predictions 15m Bimetric theories employing a disformal transformation between matter and gravity metrics are known to be capable of producing both exactly scale-invariant as well as tilted power spectra of perturbations. I will present results for the non-Gaussian signal obtained in these scenarios, which has an amplitude smaller than that of DBI inflation (with opposite sign) but larger than standard inflation. Interestingly this also gives rise to a constraint relating the spectral index and the non-Gaussian amplitude, which can be seen as a ?consistency relation? for bimetric models. In fact this constraint can be generalised and I will extend our result to apply to the general class of k-essence models. • 15:45 Mr. SALTAS, Ippocratis (University of Sussex): Anisotropic stress and stability in modified gravity models 15m The existence of the effective anisotropic stress at late times, which in this case has a purely geometrical origin, seems to be a characteristic of higher order gravity models, and its detection will be a smoking gun for departures from General Relativity, for example in future weak lensing surveys. I will discuss and investigate the possibility of the existence of modified gravity models that would be able to ''hide'' from weak lensing experiments, by giving a GR-like behavior for the lensing potentials. I will then show that this is always impossible in the context modified gravity models (such as f(R), R+ f(G) or f(R,G) ) since as it turns out to be, effective anisotropic stress is strongly linked to the actual stability of these models, and its suppression can lead to singularities. The latter fact prevents us of making the effective anisotropic stress arbitrarily small, putting this way bounds on its lower value. • 16:00 16:30 Coffee break 30m • 16:30 18:00 6 talks (Chair: Konstantinos DIMOPOULOS) • 16:30 Ms. DEMOZZI, Vittoria (LMU Munich): Non-Gaussianity in the curvaton landscape 15m We consider the curvaton scenario applied not only to the observable patch of the Universe, but to the entire Universe. On the scales of the entire Universe the homogeneous component of the curvaton field$\sigma_{0}$is a random value with a probability distribution that we can compute. The entire Universe is pictured as a curvaton landscape''. We show that the non-linearity parameter$f_{NL}$is different in different regions of the Universe depending on the distribution of$\sigma_{0}$. We can then calculate the probability distribution of the$f_{NL}$parameter for the entire Universe. This has implications for the probability of observing non-Gaussianity within our patch in the curvaton scenario. • 16:45 Mr. FONSECA, José (ICG Portsmouth): Large-scale Perturbations from the Waterfall Field in Hybrid Inflation 15m We estimate large-scale curvature perturbations from isocurvature fluctuations in the waterfall field during hybrid inflation, in addition to the usual inflaton field perturbations. The tachyonic instability at the end of inflation leads to an explosive growth of super-Hubble scale perturbations, but they retain the steep blue spectrum characteristic of vacuum fluctuations in a massive field during inflation. The power spectrum thus peaks around the Hubble-horizon scale at the end of inflation. We extend the usual delta-N formalism to include the essential role of these small fluctuations when estimating the large-scale curvature perturbation. The resulting curvature perturbation due to fluctuations in the waterfall field is second-order and the spectrum is expected to be of order 10^{-54} on cosmological scales. • 17:00 Dr. MULRYNE, David (Imperial College London): Moment transport equations for Non-Gaussianity in models with many fields 15m I will discuss inflationary models with large numbers of active fields, and numerical methods for calculating the non-Gaussianity produced in such models. In particular, I will discuss the method of `moment transport' which directly evolves the moments of the probability distribution for the curvature perturbation on super-horizon scales. • 17:15 Dr. PANOTOPOULOS, Grigoris (University of Valencia): Constraints on quintessence coupled models through energy dependent coupling 15m We study coupled quintessence models in which the interaction with dark matter is driven by some power of the quintessence potential. We show that those models can emerge from a Lagrangian formulation, and can lead to a accelerating stable fixed point. We also provide the bounds on the parameters of the models using supernovae, CMB, BAO and$H_0\$ data.
• 17:30
Dr. TAVAKOLI, Farhad (Islamic Azad University, Tehran): The effect of self-force on a freely falling massive charged particle in de-Sitter universe 15m
Observations coming from the astrophysical data indicate that we live in a expanding universe where its evolution is dominated by a small positive cosmological constant. Mathematically this model can be explained by the de Sitter space-time. In this work we study a freely falling massive charged particle in de Sitter space-time. However due to the effect of the charge and mass the particle exceeds from its geodesic. In this paper we want to consider these effects on the geodesic motion.
• 17:45
Mr. WELLER, Joel (University of Sheffield): Coupled DBI Cosmology 15m
The availability of high precision observational data in cosmology means that it is possible to go beyond the simple descriptions of cosmic inflation in which the expansion is driven by a single slowly rolling scalar field. One set of models of particular interest involve the Dirac-Born-Infeld (DBI) action, arising in string cosmology, in which the dynamics of the inflaton field are affected by a speed limit in a manner akin to special relativity. Also, the presence of additional fields during inflation is to be expected, and the question of how these fields affect the inflationary process and observables is an interesting one. In this talk, I will introduce a multi-field model in which inflation is driven by a canonical scalar field, non-minimally coupled to gravity, and a DBI field. I will explore the effect of the coupling on both fields and on the background dynamics, as well as the treatment of first-order perturbations.
• Saturday, 18 September
• 09:00 09:30
Coordinator's report on network activities
• 09:30 10:30
Reports from the Conveners on fundamental scientific tasks
• 09:30
Mariano Quiros: Origin of matter 20m
• 09:50
Manuel Drees: Origin of dark matter 20m
• 10:10
Pierre Binetruy: Origin of dark energy 20m
• 10:30 11:00
Coffee break 30m
• 11:00 12:00
Reports from the Conveners on fundamental scientific tasks
• 11:00
Gunter Sigl: Origin of cosmic rays 20m
• 11:20
David Lyth: Origin of structure 20m
• 11:40
Soo-Jong Rey: Origin of space-time 20m
• 12:00 12:15
S. Sarkar: FP7 application, Vote of thanks
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