Beyond General Relativity, Beyond Cosmological Standard Model

1 Jul 2019, 08:00 → 5 Jul 2019, 21:00 Europe/Warsaw

Faculty of Physics, University of Warsaw

Chunshan Lin (Faculty of Physics, University of Warsaw)

Cosmology provides us a unique arena where gravitation and quantum physics meet each other. It is also a unique probe of ultra-high energy physics beyond energies that can be achieved at colliders.  This conference aims at bringing together top researchers in the field to present recent breakthroughs, discuss on what we have learnt and what challenges we are still facing. The focus of this event involves several interrelated areas, from fundamental gravity theory through cosmology to new physics beyond standard model of particle physics. It includes, but not limited to:

 

(1) Physics of Primordial Universe;	(5) Black Hole Physics;
(2) Modified Gravity Theories;	(6) CMB and Large Scale Structure;
(3) Cosmological Constant Problem, Dark energy;	(7) Gravitational Waves;
(4) Dark matter, Baryon asymmetry;

The registration has opened.

A message to phd students:

We will provide local accommodations for the phd students with accepted abstract submissions (contributed talk). Therefore, if you need local support, please register yourself and submit your abstract early. 

Depending on our budget, we may provide accommodations for some small number of PhD students in poster session as well. 

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List of Invited speakers (alphabetical order)

• Celine Boehm
• Yi-fu Cai
• Mu-Chun Chen 
• Xingang Chen
• Marco Cirelli
• Anne-Christine Davis
• Emanuela Dimastrogiovanni 
• Matteo Fasiello
• Gregory Gabadadze
• Dumitru Ghilencea
• Elena Giusarma
• Andrzej Królak
• Michele Liguori
• Andrei Linde 
• Shinji Mukohyama
• Antonio Padilla
• Clem Pryke 
• Arttu Rajantie
• Graham Ross
• Misao Sasaki
• Géraldine Servant
• Alexander Vikman
• David Wands
• Yi Wang
• Marcus Werner
• Wei Xue

 

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This is the summer session of a series of seasonal workshops on gravity and cosmology, held in the Faculty of Physics, University of Warsaw. The last winter session can be found here , and the spring session can be found here . 

poster1.pdf

poster2.pdf

Monday, 1 July

08:00 → 19:50 Beyond I

Monday session

Conveners: Chunshan Lin (morning), Yi Wang (afternoon)

08:00 Reception

sandwiches, snacks, sweets, coffee, tea... are provided.

08:55 openning remarks

Speaker: Dr Chunshan Lin

09:00 Observing the Universe with Gravitational Waves

Detection of gravitational wave signals from mergers of black holes and neutron stars is one the most important discoveries of this century. I shall briefly present the phenomenon of gravitational radiation as predicted by Einstein's general relativity. I shall describe gravitational wave detectors and
methods of analyzing gravitational wave data. I shall review the observations made during the two observational runs of advanced LIGO and Virgo detector projects. I shall present the physical and astrophysical significance of these observations. I shall summarize the most recent observations of gravitational wave signals made during the third observational run of LIGO and Virgo detectors that is currently underway.

Speaker: Prof. Andrzej Królak (the leader of Polgraw-Virgo group)

Andrzej Królak.pdf

09:45 Gravitational wave energy budget in strongly supercooled phase transitions

I will discuss efficiency factors for the production of gravitational waves through bubble collisions and plasma-related sources in strong phase transitions, and the conditions under which the bubble collisions can contribute significantly to the signal. I will also show that generically the sound-wave period is much shorter than a Hubble time leading to a reduction of GW signal produced by sound waves and possibly suggesting a significant amplification of the turbulence-sourced signal. I will illustrate our findings in two examples, the Standard Model with an extra $|H|^6$ interaction and a classically scale-invariant $U(1)_{\rm B-L}$ extension of the Standard Model. The contribution to the GW spectrum from bubble collisions is found to be negligible in the $|H|^6$ model, whereas it can play an important role in parts of the parameter space in the scale-invariant $U(1)_{\rm B-L}$ model.

Speaker: Marek Lewicki (Kings College London)

MLewicki.pdf

10:05 Echoes from Quantum Black Holes

Exotic compact objects (ECOs) produce the same initial event detected by LIGO-Virgo collabo-ration as classical black holes (BHs), but various quantum gravity models feature the different following echoes. In particular, we investigate the echoes from the fluctuation-dissipation theorem [1, 2], which changes the dispersion relationship near the (would-be) horizon and results in a Boltzmann reflective boundary. We derive correspondent quasi-normal modes (QNMs) analytically. Further, wemodel the analytical and numerical echoes in the real time, which are consistent with each other. Last, we show that the superradiance is highly suppressed in the theorem.

Based on: Echoes from Quantum Black Holes(in prep.)
Fluctuation Dissipation theorem for Quantum Black Holes (in prep.)
Black Hole Echology arXiv:1803.02845v2

Speaker: Qingwen Wang

Echoes from Quantum BHs_Qingwen.key

10:25 Strong gravitational radiation from a simple dark matter model

A rather minimal possibility is that dark matter consists of the gauge bosons of a spontaneously broken symmetry. I will discuss the possibility of detecting the gravitational waves produced by the phase transition associated with such breaking. Concretely, I will focus on the scenario based on an 𝑆𝑈(2)_D group and argue that it is a case study for the sensitivity of future gravitational wave observatories to phase transitions associated with dark matter. This is because there are few parameters and those fixing the relic density also determine the effective potential establishing the strength of the phase transition. Particularly promising for LISA is the super-cool dark matter regime, with DM masses above 100 TeV, for which the gravitational wave signal is notably strong.

Speaker: Dr Camilo Garcia Cely (DESY)

Camilo Cely.pdf

10:45 Coffee break

11:15 Gravitational Wave Cosmology -The Dawn has Arrived!

Speaker: Prof. Misao Sasaki (Kavli IPMU, the University of Tokyo)

12:30 Lunch break

14:00 Stochastic inflation: slow roll and beyond

Quantum fluctuations play an essential role in the dynamics and phenomenology of inflation in the very early universe. Usually quantum fluctuations during inflation are studied perturbatively (often linearly) about a fixed classical background, but in the stochastic approach quantum fluctuations on small scales provide a stochastic contribution to the non-perturbative classical evolution on large (super-Hubble) scales. In particular the stochastic delta-N formalism can be used to study large density perturbations required to form primordial black holes. This relies on the separate universe viewpoint but does not necessarily require slow roll (though the system is particularly simple in slow roll). I will discuss some of the issues when applying the stochastic approach beyond slow-roll.

Speaker: Prof. David Wands

Wands_Warsaw_2019.pdf

14:45 Testing the Particle Dark Matter paradigm with future cosmological and astronomy surveys.

The presence of dark matter strongly suggests that the laws of Physics as we know them are incomplete. In this talk I will summarise the directions which have been explored to determine the nature of dark matter (as well as their motivations), and discuss how future cosmological and astronomy surveys will help us to progress in this field.

Speaker: Prof. Celine Boehm

15:30 Perturbatively renormalizable quantum gravity

The Wilsonian renormalization group (RG) requires Euclidean signature. The conformal factor of the metric then has a wrong-sign kinetic term, which has a profound effect on its RG properties. In particular around the Gaussian fixed point, it supports a Hilbert space of renormalizable interactions involving arbitrarily high powers of the gravitational fluctuations. These interactions are characterised by being exponentially suppressed for large field amplitude, perturbative in Newton's constant but non-perturbative in Planck's constant. By taking a limit to the boundary of the Hilbert space, diffeomorphism invariance is recovered in the continuum quantum field theory. Thus the so-called conformal factor instability is the key that allows the construction of a genuine continuum limit for quantum gravity.

[1] Tim R. Morris. Renormalization group properties in the conformal sector: towards perturbatively renormalizable quantum gravity. JHEP, 08:024, 2018, 1802.04281.
[2] Matthew P. Kellett and Tim R. Morris. Renormalization group properties of the conformal
mode of a torus. Class. Quant. Grav., 35(17):175002, 2018, 1803.00859.
[3] Tim R. Morris. Perturbatively renormalizable quantum gravity. Int. J. Mod. Phys.,
D27(14):1847003, 2018, 1804.03834.
[4] Tim R. Morris. Quantum gravity, renormalizability and di?eomorphism invariance. SciPost
Phys., 5:040, 2018, 1806.02206.
[5] Tim R. Morris. to appear.

Speaker: Tim Morris (Southampton University)

Tim Morris.pdf

15:50 coffee break

16:20 Understanding the dynamical nature of late-time cosmic acceleration from dark energy and f(T) modified gravity

In this talk I will briefly introduce the present understanding about the cosmic acceleration at present from the perspective of phenomenological study. I will review the latest observational status of the late-time cosmic acceleration and then depict how to do the model building of dynamical dark energy. Afterwards, I will also give an introduction to a type of torsional based modified gravity, which can also realize the cosmic acceleration at present. This so-called f(T) gravity and beyond theories can be depicted in a language of effective field theory and thus we can examine certain operators that are most connected with various cosmological observations.

Speaker: Prof. Yi-fu Cai (University of Science and Technology of China)

Cai_DEfT_20190701a.pdf

17:05 Cosmological implications of the electroweak vacuum instability

When extrapolated to high energies, the Standard Model of particle physics predicts that the current vacuum state is metastable. Its predicted decay rate is currently extremely low, but it would have been much higher in the early Universe. Therefore the fact that the Universe survived its first moments places constraints on both the cosmological history and on particle physics. I will discuss and review these constraints, focussing particularly on the bounds that can be obtained for the non-minimal couplings between the Higgs field and spacetime curvature.

Speaker: Prof. Arttu Rajantie

Rajantie_Warsaw_2019.pdf

Rajantie_Warsaw_2019.pptx

17:50 Is Vacuum Decay During Inflation Fatal?

If the Standard Model vacuum is metastable, bubbles that form expand and convert the entire vacuum into a true vacuum state incompatible with observations. It is sometimes argued, however, that true vacuum bubbles forming during inflation are 'inflated away' and thus pose no danger to the present day universe, even if they form. I will argue that this point of view is incorrect - while the exponential expansion of spacetime does affect the evolution of true vacuum bubbles, they do not, in fact, collapse to nothing and can in fact survive to the present day. Consequently, the electroweak vacuum instability must be fixed or circumvented if high scale inflation is to take place, providing strong hints that there must be new physics before the Planck scale.

Speaker: Dr Stephen Stopyra (University College London)

stephen_stopyra.pdf

18:10 Could the H0 Tension be Pointing Toward the Neutrino Mass Mechanism?

Within the framework of $\Lambda$CDM, the local determination of the Hubble constant disagrees -- at the 4.4$\sigma$ level -- with that inferred from the very accurate CMB observations by the Planck satellite. This clearly motivates the study of extensions of the standard cosmological model that could reduce such tension. Proposed extensions of $\Lambda$CDM that reduce this so-called Hubble tension require an additional component of the energy density in the Universe to contribute to radiation at a time close to recombination.

In this talk, I will show that pseudo-Goldstone bosons -- associated with the spontaneous breaking of global lepton number in type-I seesaw models -- lead to a non-standard early Universe evolution that can help to reduce the Hubble tension. I will show that current CMB observations can set a lower bound on the scale at which lepton number is broken as high as 1 TeV. Finally, I will argue that future CMB observations will test wide and relevant regions of parameter space of scenarios in which the spontaneous breaking of global lepton number is the mechanism behind the observed neutrino masses.

Speaker: Miguel Escudero (King's College London)

Escudero_Beyond_Warsaw_2019.pdf

Tuesday, 2 July

08:45 → 19:20 Beyond II

Conveners: Prof. Celine Boehm (morning), Marcus Werner (afternoon)

08:45 Dark Matter Indirect Detection

Speaker: Prof. Marco Cirelli

11.DMid.Warsaw.pdf

10:00 Hunting Axion Dark Matter with New Techniques

Identification of dark matter has been an outstanding problem in physics for decades, and axion (or axion like partciles) is its candidate with great motivations. A number of observations and experiments have tried to detect axion by using the axion-photon conversion by assuming the axion is coupled to photon, while no signal yet to be found. In this talk, I will discuss new techniques to search for axion dark matter (ADM) by focusing on another phenomena, birefringence, which is caused by the same coupling. The polarimetry observation of protoplanetary disks puts the best constraint on ADM for fuzzy dark matter mass (m = 10^{-22}eV). I also propose to use gravitational wave interferometer like LIGO for ADM search by installing a new detector which does not affect the detection of gravitational waves.

Speaker: Tomohiro Fujita (Kyoto University)

Fujita_talk.pdf

Fujita_talk.pptx

10:20 coffee break

10:50 Searching for Dark Matter across different Scales

In this talk, I will discuss the methods to search for dark matter or dark sector particles having the masses from GeV to the Solar Mass. We can probe their properties by colliders, neutrino or gamma ray experiments.

Speaker: Dr Wei Xue

DM_beyond2019_weixue.pdf

11:35 Light Dark Matter from Inelastic Cosmic Ray Collisions

Direct detection experiments relying on nuclear recoil signatures lose sensitivity to sub-GeV dark matter for typical galactic velocities. This sensitivity is recovered if there exists another source of flux with higher momenta. Such an energetic flux of light dark matter could originate from the decay of mesons produced in inelastic cosmic ray collisions. I present in this talk the dark matter flux expected from such cosmic beam dump experiment and the resulting limits on the model parameters using direct detection experiments such as XENON1T and the projected LZ. A particular model involving a hadrophilic scalar mediator is also considered and I show how the limits compare with dedicated beam dump experiments such as MiniBooNE.

Speaker: Miguel D. Campos (King's College London)

Campos.pdf

11:55 Dark matter and baryon-number generation in quintessential inflation via hierarchical right-handed neutrinos

Incorporating three generations of right-handed Majorana neutrinos to quintessential inflation, we construct a model which simultaneously explains inflation, dark energy, dark matter and baryogenesis. These right-handed neutrinos have hierarchical masses $M_3 \sim 10^{13}$GeV, $M_2 \sim 10^{11}$GeV, $M_1 \sim 10$keV and are produced by gravitational particle production in the kination regime after inflation. The heaviest, the intermediate, and the lightest account for reheating, CP violation of leptogenesis, and dark matter, respectively. We consider various constraints from particle experiments and cosmological observations. If we adopt the Randall-Sundrum brane-world scenario, these constraints on parameters are satisfied without fine-tuning.

This talk is based on 1905.12423.

Speaker: Soichiro Hashiba

SoichiroHashiba.pdf

12:15 Poster session

1 minute 1 slide oral presentation;

Speakers: Aya IYONAGA, Bryce Cyr, Daniel Kristoffer Blixt, Emmanuel Frion, Francesco Pace, Jaksa Osinski, Jan Olle, Juho Lankinen, Laura Iacconi, Manuel Hohmann, Matteo Cinus, Michael Kenna-Allison, Mohammad Malekjani, SAMIR IRAOUI, Sebastián Bahamonde Beltrán, Tays Miranda de Andrade, Xin Ren, Yin Lu, Yun-Long Zhang

affine_quant_BDT_bullet.pdf

Blixt.pdf

Bryce.pdf

Iraoui_Samir.pdf

iyonaga.pdf

Jan_Olle.pdf

Lankinen.pdf

Laura Iacconi .pdf

LuYin.pdf

LuYin.pptx

MatteoCinus.pdf

M. Malekjnai.pdf

12:45 Lunch break

14:00 Gravity and cosmology beyond Einstein

I will give an introductory review talk on extensions of general relativity, covering the following contents.
1. Introduction
2. General relativity and Lovelock gravity
3. PPN formalism
4. EFT approach
5. Massive gravity
6. Summary

Speaker: Prof. Shinji Mukohyama

190702mukohyama.pdf

15:15 Einstein-Gauss-Bonnet gravity in four space-time dimensions

Lovelock's theorem asserts that the most general theory of gravity in D=4 space-time dimensions is given by the action containing the Einstein-Hilbert term and a cosmological constant. Already in D=5 an additional term is possible - the Gauss-Bonnet action - which in D=4 turns into a total derivative not contributing to dynamics. In general, the contribution of the Gauss-Bonnet action to Einstein equation is proportional to (D-4). Here I will present an idea of multiplying the Gauss-Bonnet action by 1/(D-4) and defining the four-dimensional case as a smooth D->4 limit of the Einstein equation. Thus defined the theory propagates only the graviton and it satisfies the criteria of Lovelock's theorem, but bypasses its results. This theory has several novel predictions, including the corrections to the dispersion relation of cosmological tensor and scalar modes and singularity resolution for spherically symmetric solutions.

Speaker: Dr Drazen Glavan

15:35 coffee break

16:05 Gravitational Effects of Disformal Couplings

Speaker: Prof. Anne-Christine Davis (DAMTP, Cambridge University)

Davis.pdf

16:50 Resolving the strong coupling problem in massive gravity

Theories of massive gravity and their generalizations have been used for the description of the late time and early universe cosmologies. These theories however are strongly coupled at a certain low energy scale. We show how this problem can be avoided by embedding massive gravity and its generalizations into higher dimensional theories.

Speaker: Prof. Gregory Gabadadze

Gabadadze_Warsaw_new.pdf

17:35 Massive Gravity on a Brane

dRGT theory is the unique ghost-free theory of massive gravity and it realizes a full nonlinear completion of the linear Fierz-Pauli theory for a massive spin-2 field. In addition to being an interesting field theoretic modification of General Relativity, it could potentially explain the late-time cosmic acceleration of our universe as an alternative to a small cosmological constant. However, dRGT is an effective field theory with a very low strong coupling scale $\Lambda_3 \sim (1000 km)^{-1}$ and in order to have a consistent modification of gravity that is compatible with short distance tests of GR, the theory must be UV completed in some way. It seems that a UV completion analogous to the Higgs mechanism for massive non-Abelian gauge theory will not work in flat space but there does exist a known mechanism for dynamically generating mass for the graviton in AdS space. We utilize this mechanism in a Randall-Sundrum-like scenario where our world is a flat boundary of a cutoff AdS space. The dRGT action is on the boundary and the bulk has gravity coupled to scalar fields that dynamically gains a mass. This massive graviton then has a 'zero-mode' which plays the role of the graviton on the brane and it's effective 4d dynamics are such that they raise the cut-off of massive gravity from $(1000 km)^{-1} \sim 10^{-19} MeV$ to as high as $10^{19} MeV$.

Speaker: Daniel Older

older.key

17:55 Cosmology of models with spontaneous scalarization: instability and a cure.

I will discuss scalar-tensor models of gravity, which predict the spontaneous scalarization of neutron stars or/and black holes. In the cosmological setup, the scalar field responsible for scalarization is subject to a tachyonic instability during inflation as well as at other cosmological stages, depending on the model. The instability poses a problem for viability of such models. I will show that for the case of scalarization with the Gauss-Bonnet term, a catastrophic instability develops during inflation within a period of time much shorter than the minimum required duration of inflation. As a result, the standard cosmological dynamics is not recovered. On the other hand, in the case of standard scalarization by Damour-Esposito-Farese, it is possible to make a simple modification of the original model by coupling the scalar to the inflaton field. For generic couplings the scalar (including its perturbations) relaxes to zero with an exponential accuracy by the beginning of the hot stage.

Speaker: Dr Eugeny Babichev (Paris-Sud University)

Babichev.pdf

18:15 Role of matter in modified gravity: a search for new interactions

Modified gravity theories are typically constructed in the Jordan frame, where the matter follows the geodesics of the metric. This is nothing more than a choice of field variable that leaves the observables intact. However recent developments in classical field theory revealed that fixing variables may affect how the fundamental assumptions in the theory building process are represented. For instance, the construction of "beyond-Horndeski" theories in the Jordan frame representation requires an intricate constraint analysis to exploit degeneracies, while using different variables one can obtain arguably simpler formulations within the framework of standard (i.e. Horndeski) scalar-tensor theory.

In this talk, I will adopt Bekenstein's perspective of multiple geometries and consider two applications where a generic matter coupling unveils new interactions: i. a massive spin--2 theory; ii. a vector-tensor theory with an Abelian gauge field.

Speaker: Dr Emir Gumrukcuoglu (Institute of Cosmology and Gravitation, Portsmouth)

Gumrukcuoglu and Beyond.pdf

Wednesday, 3 July

08:15 → 13:30 Beyond III

Convener: Prof. Zygmunt Lalak

08:45 Scale invariance, Stueckelberg breaking of Weyl gravity and inflation

Weyl conformal geometry may play a role in early cosmology where effective theory at short distances becomes conformal. We consider the original Weyl gravity action, quadratic in the scalar curvature and in the Weyl tensor of Weyl conformal geometry; this action is invariant under Weyl scaling gauge transformations. In the absence of matter fields, we show that Weyl action has spontaneous breaking of this symmetry: the Weyl gauge field (of local scale transformations) becomes massive (mass ~ Planck scale) after absorbing a compensator (dilaton), in a gravitational Stueckelberg mechanism. As a result, one obtains the Einstein-Hilbert action, a positive cosmological constant and the Proca action for the massive Weyl gauge field ("photon"). The Einstein-Hilbert action is then just a "low energy" limit of Weyl quadratic gravity which thus avoids its long-held previous criticisms, while Planck scale is an emergent scale of this symmetry breaking (where Weyl geometry becomes Riemannian). The results remain valid in the presence of matter with non-minimal coupling. Successful inflation in Weyl gravity is possible, with results close to the Starobinsky model. Based on arXiv:1812.08613, 1904.06596.

Speaker: Prof. Dumitru Ghilencea (IFIN)

ghilencea-v2.pdf

09:30 Quantum scale invariance, hierarchy generation and inflation

Global and local Weyl invariant theories can solve the hierarchy problem and generate all mass scales spontaneously, initiated by a dynamical process of “inertial spontaneous symmetry breaking” that does not involve a potential. I will discuss how inflation readily occurs in a scale invariant version of Starobinsky (R2) inflation and how an hierarchy of mass scales may be generated, stable against both Standard Model and gravitational quantum corrections.

Speaker: Prof. Graham Ross (Oxford University)

GGRoss.pdf

10:15 Beyond Standard Model and Asymptotically Safe Gravity

Einstein gravity cannot be quantised using standard Quantum Field Theory techniques. Hence to describe gravity on quantum level then either a new, special quantisation prescription should be proposed or General Relativity should be replaced by another theory which can be properly quantised. If the first option is true, then General Relativity should possess an interacting UV fixed point (as an asymptotically safe theory) and then GR becomes a fundamental Quantum Field Theory to arbitrary scales. There are many hints that indeed it is so.

On the other hand there are many proposals on how to extend the Standard Model, designed to deal with its fundamental inconsistencies. Since no new particles have been detected experimentally so far, the models which add only one more scalar particle and possibly right-chiral neutrinos are favoured. One of such models is the Conformal Standard Model.

If there are no intermediate scales between electroweak and Planck scale then these type of models supplemented with asymptotically safe gravity can be valid up to arbitrarily high energies and give a complete description of particle physics and gravitational phenomena.

This assumption restricts the mass of the second scalar particle to 300 +/-28 GeV and the mass of Higgs boson at 125 +/- few GeV. This has also impact on the multiple Higgs inflation scenarios.

Whats more various theories of gravity gives various predictions for the Higgs boson masses. Hence then by accurate measurements we can investigate the quantum gravity in LHC.

Talk based on the articles: https://arxiv.org/abs/1810.08461, arXiv:1712.03778 and unpublished results in collaboration with Frederic Grabowski and prof. Krzysztof A. Meissner.

Speaker: Mr Jan Kwapisz (Faculty of Physics, University of Warsaw)

Kwapisz.pdf

10:35 coffee break

11:05 Flavor, CP, and Baryons

I will review flavor models based on non-Abelian discrete symmetries, motivated by neutrino oscillation data. I will discuss how CP violation, a necessary condition for baryogenesis, can be entirely group theoretical in origin in certain class of the non-Abelian discrete groups. I will then describe a proposal where successful baryogenesis can be achieved through flavon decays.

Speaker: Prof. Mu-Chun Chen (University of California, Irvine)

2019Beyond_MCChen.pdf

11:50 Self-stopping relaxion

I will review the mechanism of cosmological relaxation of the electroweak scale and will discuss relaxion particle production during the evolution of the relaxion field, an effect which had been so far ignored in the relaxion literature. I will present its implications on the relaxion mechanism in general.

Speaker: Prof. Géraldine Servant (DESY)

12:35 Neutrino Cosmology - Weighing the Ghost Particle with the Universe

Over the past decades, the high-precision cosmological data have significantly improved our understanding of the Universe, contributing greatly to the establishment of the standard model of cosmology. However these results have also opened new questions in both fundamental physics and astrophysics. One of the great mystery of the universe is that more than 80% of the matter in our Universe is made up of material that is invisible (dark matter). This component has important consequences in the evolution of the Universe and in the structure formation processes. While the major contribution to the dark matter should arise from cold dark matter (CDM), a small component of hot dark matter (HDM) can also be present. A natural candidate for the HDM is neutrino. Neutrinos physics is one of the most fascinating research areas that has stemmed from the interplays between cosmology, astrophysics and particle physics. Cosmology provides an independent tool for the investigation of neutrino properties since it is sensitive to the absolute scale of neutrino masses. Measuring the masses of these particles would be of extreme value to unravel the departure from the Standard Model (SM) of Particle Physics. A robust detection of neutrino masses is among the key goals of upcoming Cosmic Microwave Background (CMB) and Large-Scale Structure (LSS) surveys. In this talk, I will review the main physical effects of massive neutrinos on cosmological observable and summarize recent progress on neutrino mass constraints obtained by combining different cosmological measurements. I will also show a new approach to produce fast non-standard cosmological simulations with massive neutrinos by applying deep learning algorithms.

Speaker: Dr Elena Giusarma (Flatiron Institute, New York)

Giusarma_Warsaw.pdf

13:30 → 14:30 lunch break

16:45 → 17:45 time for Chopin

Address: plac Zamkowy 8/Plac Zamkowy, 00-277 Warszawa

19:00 → 22:00 banquet

Restauracja Pod Gigantami
Address: al. Ujazdowskie 24, 00-535 Warszawa

Thursday, 4 July

08:45 → 19:45 Beyond IV

Conveners: Prof. Misao Sasaki (morning), Prof. Yifu Cai (afternoon)

08:45 Reverse Engineering the Universe

I will give a brief review of inflationary cosmology, including its motivation, observational status, the problem of initial conditions, and the string landscape scenario. I will also describe the problems with hilltop inflation and then I will show that the theory of alpha-attractors and D-brane inflation together can completely cover the range or values of n_s and r favored by Planck 2018.

Speaker: Andrei Linde (Stanford University)

Linde Warsaw.pdf

10:00 Probing the Inflationary Field Content with Primordial Gravitational Waves and more.

The inflationary paradigm, already in its simplest disguises, has been spectacularly successful when it comes to agreement with observations. However, there’s a lot we do not yet know about inflation:
- what is its energy scale?
- how about its particle content?
- how did inflation begin?
…

New cosmological probes (at all scales, from CMB to interferometers) will soon put some of our best ideas to the test.
The answers to these questions are bound to be transformative of our understanding of cosmology and, possibly, also particle physics. A high-scale inflation, for example, would automatically be a portal to otherwise unaccessible energy scales.
In this talk I will review some recent work on the inflationary particle content and then focus on a model that includes a pseudo scalar field coupled with SU(2) gauge fields. This setup can generate a chiral gravitational waves signal. I will then detail on how the parameter space of the theory supports a blue tensor spectrum and large tensor as well as mixed non-Gaussianities.

Speaker: Matteo Fasiello (ICG Portsmouth)

Fasiello_Warsaw_2.pdf

10:20 coffee break

10:50 The Search for Inflationary B-modes with the BICEP/Keck Telescopes

The LCDM cosmological model fits a wealth of observational data extremely well but assumes a very specific type of initial conditions (near-scale-invariant, Gaussian, adiabatic perturbations). Inflationary theories can naturally produce these initial conditions, while also generically predicting a background of gravitational waves---which have so far not been detected. There are a wide range of inflationary models which make different predictions for the strength of the gravitational wave background, which is customarily characterized by the scalar-to-tensor ratio $r$. Primordial gravitational waves will have left an imprint in the polarization pattern of the cosmic Microwave Background (CMB) which we can potentially detect as a curl component, or B-mode, in the pattern at degree angular scales. The BICEP/Keck series of experiments are small aperture refracting telescopes specifically designed to search for this signal. The latest BK15 results use measurements at 95, 150 and 220GHz, in conjunction with additional bands from WMAP and Planck, to constrain the foreground signal and set the limit $r<0.07$ (95% confidence). I will describe the current instruments, data and analysis, and also the major BICEP Array upgrade which is projected to reach sensitivity of $\sigma(r)\sim0.003$ within the next five years.

Speaker: Prof. Clem Pryke

11:35 Testing primordial Non-Gaussianty: perspectives beyond Planck

Tests of primordial non-Gaussianity (PNG) are a powerful tool to shed light on the physics of the Early Universe. Currently, the best limits on PNG come from Planck measurements of Cosmic Microwave Background (CMB) temperature and polarization anisotropies, which nearly saturated the CMB constraining power. After briefly reviewing current Planck PNG bounds for a variety of models, I will discuss how these could be further improved in the future using different probes, such as galaxy clustering, or CMB B-mode polarization and spectral distortions.

Speaker: Prof. Michele Liguori (University of Padova)

Liguori.pdf

12:20 Shift-symmetric orbital inflation: single field or multi-field?

Multi-field inflation with curved field manifold attracts a lot of attention recently. From theoretical aspect, this class of models may be more naturally realized in the UV completion of inflation. From observational point of view, however, the current constraints on primordial non-Gaussianity and isocurvature perturbation already/marginally ruled out many of these models. In this talk I will introduce a new class of two-field inflationary attractors, known as ‘shift-symmetric orbital inflation’. It is strongly multi-field, but the phenomenology still mimics single-field inflation, since in the end only one degree of freedom (the one with isocurvature origin) is responsible for the prediction of primordial perturbations. This new regime of multi-field attractors provides a different perspective to explore UV completion of inflation, which is free from the problems faced by single field models.

Speaker: Mr Dong-Gang Wang (Leiden University)

DG-Wang.pdf

12:40 lunch break

14:00 Updates on the Cosmological Collider Physics

We review quasi-single field inflation and the cosmological collider physics, emphasizing on recent progress. The cosmological collider is a model-independent way of extracting the mass and spin information of heavy particles at the energy scale of inflation. The same mechanism can also be used as a direct probe of the expansion history of the universe. After the introduction, we survey the recent progress including neutrino physics, particle scanner, superheavy dark matter, tests of particle symmetries and the tension of today's Hubble parameter measurements.

Speaker: Prof. Yi Wang (Hong Kong University of Science and Technology)

CC_YW.pdf

14:45 Primordial Standard Clocks as Direct Probes of the Scenario of the Primordial Universe

How to model-independently distinguish the inflation scenario from alternatives to inflation is an important challenge in modern cosmology. In this talk, we show that massive fields in the primordial universe function as standard clocks and imprint clock signals in the density perturbations, which directly record the scale factor of the universe as a function of time, a(t). This function is the defining property of any primordial universe scenario, so can be used to identify the inflation scenario, or one of its alternatives, in a model-independent fashion. The signals also encode the mass and spin spectra of the particle physics at the energy scale of the primordial universe.

Speaker: Prof. Xingang Chen (Harvard University)

Chen 190703 Warsaw.pdf

15:30 Stability of de Sitter spacetime against the backreaction of the infrared modes of scalar fields

We study the back-reaction of the infrared modes of an O(N) scalar theory in a classical de Sitter background. We use the nonperturbative renormalization group methods to extract analytically the flow of the Hubble constant as the gravitationally enhanced long wavelength modes are integrated out. For a massless theory, the interactions tend to renormalize negatively the Hubble constant, thus drawing energy from the classical gravitational field. This phenomenon saturates however, and unbounded loop corrections are screened by nonperturbative effects which stabilise the geometry.

Based on : G. Moreau and J. Serreau, Phys. Rev. Lett. 122 (2019) no.1, 011302, Phys. Rev. D 99 (2019) no.2, 025011

Speaker: Gabriel Moreau (Université Paris Diderot)

Moreau.pdf

15:50 coffee break

16:20 Monodromy inflation and an emergent mechanism for stabilising the cosmological constant

We show how a pair of field theory monodromies in which the shift symmetry is broken by small, well motivated deformations, naturally incorporates a mechanism for cancelling off radiative corrections to the cosmological constant. The lighter monodromy sector plays the role of inflation as well as providing a rigid degree of freedom that acts as a dynamical counterterm for the cosmological constant. The heavier monodromy sector includes a rigid dilaton that forces a global constraint on the system and the cancellation of vacuum energy loops occurs at low energies via the sequestering mechanism. This suggests that monodromy constructions in string theory could be adapted to incorporate mechanisms to stabilise the cosmological constant in their low energy descriptions.

Speaker: Prof. Tony Padilla (University of Nottingham)

Padilla.pdf

17:05 Primordial-Black-Holes-as-CDM Scenario and Gravitational Waves

Speaker: Misao Sasaki

Sasaki GW+PBH-Warsaw.pdf

17:25 Cosmic Inflation and Dark Energy from the Electroweak Phase Transition

Cosmic inflation is a period of accelerated expansion in the Early Universe. Inflation is the most compelling proposal for the formation of of the observed structures in the Universe like galaxies and galactic clusters. It also makes the Universe uniform and spatially flat in agreement with observations. To drive inflation an exotic substance is needed, with pressure negative enough to cause the expansion of the Universe to accelerate, when this substance is dominant. Observations suggest that the late Universe is also undergoing accelerated expansion, which is assumed to be due to another exotic substance called dark energy. Can this be the one and the same with the substance behind inflation? In this talk I present a novel idea, in which inflation leaves behind a minute potential density, which can become the dark energy observed today. The field responsible for inflation (inflaton), is trapped in a local minimum of its scalar potential until the electroweak phase transition. The transition releases the field and allows it to vary slowly down a shallow potential tail, becoming dark energy. This behaviour is facilitated by a suitable coupling between the inflaton field and the electroweak Higgs field. The model is successful without fine-tuning, because it makes use of the curious fact that the electroweak energy scale is roughly the geometric mean of the Planck scale and the dark energy scale.

Speaker: Dr Konstantinos Dimopoulos (Lancaster University)

Dimopoulos.pdf

Dimopoulos.ppt

17:45 Complementary probes of cosmic inflation

A rigorous constraint analysis on inflationary cosmology entails several probes which collectively survey an extensive range of energy scales. We complement the current cosmic microwave background data with an updated compilation of the cosmic abundance limits of primordial black holes, with which we infer stringent constraints on the runnings of the scalar spectral index. The constraints on the higher-order inflationary power spectrum parameters are notably improved by further including imminent measurements of the cosmic microwave background spectral distortions, clearly illustrating the effectiveness of joint large-scale and small-scale cosmological surveys.

Based on arXiv:1904.09590.

Speaker: Jurgen Mifsud (Korea Astronomy and Space Science Institute)

mifsud.pdf

18:05 Constant roll warm inflation

I will present the idea of combinig the constant roll inflation with the warm inflationary paradigm, which comes from the strong particle production during inflation. I will show how to solve such a system and I will rpesent fundamental applications of this theory: from inflation to primordial black holes production

Speaker: Dr Michal Artymowski (Jagiellonian University)

Artymowski.pdf

Friday, 5 July

08:45 → 20:45 Beyond V

Conveners: Alexander Vikman (afternoon), Shinji Mukohyama (morning)

08:45 Weyl Symmetry for Dark Matter and Dark Energy

I will start by reviewing the mimetic formulation for irrotational fluid-like Dark Matter. It turned out that the latter can be described by a Weyl-invariant higher-derivative scalar-tensor theory beyond the Horndeski class of theories. Then I will proceed by discussing a novel vector extension of the mimetic construction. This novel vector-tensor theory provides a Weyl-invariant higher-derivative and generally covariant description for the unimodular gravity.

Speaker: Prof. Alexander Vikman

Warsaw_summer_Vikman.pdf

09:30 Nonlocal Quantum Gravity

We present a weakly nonlocal gravitational theory unitary and finite at quantum level in the quantum field theory framework. As a consequence of finiteness, there is no Weyl anomaly and the theory turns out to be conformal invariant at classical as well at quantum level. Therefore, nonlocal quantum gravity is a conformal invariant theory in the spontaneously broken phase of the Weyl symmetry. As an application, Weyl conformal symmetry solves the black hole's singularity issue and cosmological singularity problem, otherwise unavoidable in a generally covariant local or non-local gravitational theory. Following and extending the seminal paper by Narlikar and Kembhavi, we provide explicit examples of singularity-free black hole exact solutions. The absence of divergences is based on the finiteness of the curvature invariants and on showing that the new types of black holes are geodesically complete. Indeed, no massive or massless particle can reach the former singularity in a finite amount of proper time or of affine parameter.

Speaker: Leonardo Modesto (SUSTech)

Leonardo Modesto.pdf

09:50 Scalar-tensor theories beyond Riemannian

We discuss scalar-tensor theories based on a non-Riemannian geometry, called the metric-affine geometry, where the metric and the connection are treated as independent variables. In the metric-affine formalism, the Einstein-Hilbert action enjoys an additional local symmetry, the projective symmetry, under a shift of the connection. We find that the projective symmetry can provide an Ostrogradky ghost-free structure of general scalar-tensor theories. The ghostly sector of the second-order derivative of the scalar is absorbed into the projective gauge mode when the unitary gauge can be imposed. We also find that, up to the quadratic order of the connection, the most general projective invariant theory is equivalent to the U-degenerate theory when the connection is integrated out and, if we further assume the Galileon-type self-interactions, the theory is equivalent to DHOST theory.

[1] Katsuki Aoki and Keigo Shimada, Galileon and generalized Galileon with projective invariance in a metric-affine formalism, 1806.02589.
[2] Katsuki Aoki and Keigo Shimada, Scalar-metric-affine theories: Can we get ghost-free theories from symmetry?, 1904.10175.

Speaker: Katsuki Aoki (Yukawa Institute for Theoretical Physics, Kyoto University)

Aoki@Warsaw.pdf

10:10 coffee break

10:40 Metric Optical Geometry and Beyond

Optical geometry is a spatial formalism for light propagation in Lorentzian spacetimes. This provides a geometrically interesting and useful framework for gravitational lensing, which is usually treated in terms of the quasi-Euclidean standard approximation instead. In this talk, I will first consider Riemannian optical geometry, and review basic results as well as recent work using the Gauss-Bonnet theorem and curve-shortening flow. In particular, the first isoperimetric inequality in this context will be presented. Then going beyond metric geometry, I will consider possible extensions to Randers-Finsler optical geometry, which arises for stationary spacetimes, and show a connection with the magnetoelectric effect. Finally, a framework for optics in non-metric spacetimes will be discussed.

Speaker: Prof. Marcus Werner (YITP, Kyoto University)

beyond19-werner.pdf

11:25 Constraining primordial gravitational waves from inflation

I discuss the prospects for constraining gravitational waves from non-minimal inflationary models using: (i) the large scale structure, through the so-called "fossil" signatures; (ii) cross-correlations of tracers of the large scale structure with secondary CMB anisotropies from kinetic and polarized Sunyaev–Zel'dovich effects. I show how these different routes for testing primordial gravitational waves will help us learn more about the early universe.

Speaker: Prof. Emanuela Dimastrogiovanni

ema.pdf

12:10 Possible resolution of a spacetime singularity with field transformations

In this talk, we show that there is a class of spacetime curvature singularities which can be resolved with metric and matter field transformations. As an example, we consider an anisotropic power-law inflation model with gauge and scalar fields in which a space-like curvature singularity exists at the beginning of time. First, we provide a transformation of the metric to the flat geometry. The transformation is regular in the whole region of spacetime except for the singularity. In general, matter fields are still singular after such a metric transformation. However, we explicitly show that there is a case in which the singular behavior of the matter fields can be completely removed by a field re-definition. Since the action is invariant under any metric and matter field transformations, the regularity of the action at the original singularity is a necessary condition for the complete removal of a singularity.

Speaker: Prof. Atsushi Naruko

naruko.pdf

12:30 lunch break

14:00 Emergent inflation from a Nambu–Jona-Lasinio mechanism in gravity with non-dynamical torsion

We discuss how inflation can emerge from a four-fermion interaction induced by torsion. Inflation can arise from coupling torsion to Standard Model fermions, without any need of introducing new scalar particles beyond the Standard Model. Within this picture, the inflaton field can be a composite field of the SM-particles and arises from a Nambu-Jona-Lasinio mechanism in curved space-time, non-minimally coupled with the Ricci scalar. The model we specify predicts small value of the r-parameter, namely r ~ 10−4 ÷ 10−2, which nonetheless would be detectable by the next generation of experiments, including BICEP 3 and the AliCPT projects.

Speaker: Antonino Marciano (Fudan University)

Warsaw2019 (1).pdf

14:20 Primordial Kerr Black Holes

Primordial Black Holes (PBHs) are appealing candidates for dark matter in the universe but are severely constrained by theoretical and observational constraints. I will focus on the Hawking evaporation limits extended to Kerr Black Holes. These results have been obtained with a new to-be-published code entitled BlackHawk that I will briefly present. In particular, I will review the isotropic extragalactic gamma ray background constraint and show that the "window" in which PBHs can constitute all of the dark matter depends strongly on the PBH spin. Finally, I will give some tools that could be used to distinguish between Black Holes of primordial or stellar origin based on the Thorne limit on their spin.

Speaker: Mr Jérémy Auffinger (Institut d'Astrophysique de Paris)

Auffinger_Jérémy.pdf

14:40 Hamiltonians & degrees of freedom in "Lorentz-violating" field theories

Many classical field models which "violate Lorentz symmetry" do so via a vector or tensor field which takes on a vacuum expectation value, thereby spontaneously breaking the underlying Lorentz symmetry of the Lagrangian. To obtain a tensor field with this behavior, one can posit a smooth potential for this field, or one can enforce a non-zero tensor value via a Lagrange multiplier. In this talk, I will discuss the unexpected effects that can arise when one tries to construct a field model in this way. In particular, the number of degrees of freedom of the model is not necessarily reduced, compared to a theory with a smooth potential, when one "constrains" the field via a Lagrange multiplier; and for certain field theories with a potential, the equations of motion do not allow the field to evolve smoothly on and off of the vacuum manifold.

Speaker: Michael Seifert (Connecticut College)

Seifert_Beyond_conference_talk.pdf

15:00 Minimalism in modified gravity

It is generally believed that modification of GR inevitably introduce extra physical degree(s) of freedom. In this talk I argue that this is not the case by constructing modified gravity theories with two local physical degrees of freedom. After classifying such theories into two types, I show explicit examples and discuss their cosmology and phenomenology.

Speaker: Prof. Shinji Mukohyama

190705mukohyama_MMG.pdf

15:20 coffee break

15:50 Information Missing Puzzle, Where Is Hawking's Error?

We will discuss in our talk a picture for blackholes' inner structure and microscopic state in which matters falling into the horizon or consisting of them are oscillating around instead of accumulating statically on their central point, thus resolving the Schwarzschild singularity naturally. After quantizing, this picture not only blurs the horizon remarkably, but also provides an interpretation for the Bekenstein-Hawking entropy as measures of the number of consisting matters' oscillation modes. Since each microscopic blackhole has its own dynamic mass distribution and special $r_h$-$t$ curve when evaporating and distinguishable from each other, thermal features of the Hawking radiation are only averaged description of many such objects with equal mass and symmetry. As conclusion, we claim that Hawking' error in the information missing puzzle lies in taking the averaged ensemble behavior of many microscopic blackholes with equal mass and symmetry as features of a special microscopic one.

Speaker: Ding-Fang Zeng

dfzeng-talks-poland-41.pdf

16:10 Macroscopic effects on neutralino dark matter depletion through large R-charge

The presence of a large, non-vanishing background charge in the universe can interestingly have implications on symmetry restoration at high temperature. In theories with continuous global symmetries, like the R-symmetry of the MSSM, these can lead to important cosmological effects seemingly independent of the short-distance scale physics. Here we explore the effect of temporary R-symmetry violation on the density of neutralino dark matter in the presence of a large initial R-charge in the early universe. In particular, this behaviour may be important for models in which the dark matter experiences feeble annihilation rates with the primordial plasma, common in supersymmetric models.

Speaker: Matthew Talia (University of Sydney)

BEYOND2019_TALIA.pdf

16:30 Electroweak baryogenesis and dark matter from a complex singlet scalar

We connect the electroweak (EW) baryogenesis and the dark matter physics in a complex singlet scalar S extension of the Standard Model. We impose the additional CP and Z_2 symmetries on the scalar potential. With the complex vacuum expectation value of S at the temperature higher than the EW phase transition, the CP symmetry is spontaneously broken and a strong first-order EW phase transition is easily realized. Together with a dimension-6 effective operator that gives new complex contributions to the top quark mass, we show that it is easy to yield the observed baryon asymmetry in our Universe. On the other hand, the CP and Z_2 symmetries are recovered after the EW phase transition. The lighter real state in S can be the dark matter candidate, and the strong constraints of CP violations can be avoided. With the scan of parameter space, we can find models which can explain the dark matter relic abundance and the baryon asymmetry simultaneously while satisfying all constraints.

Speaker: Da Huang (University of Warsaw)

DMBG_Beyond.pdf

16:50 Current status of smooth quantum gravity

Smooth QG is the attempt to use findings and infinite geometric constructions of differential geometry and topology in dimensions 3 and 4, to solve problems in physics, especially gravitational physics. The relation between general relativity and quantum mechanics is of particular interest. We report the recent result of G. Etesi that large exotic R4's are Ricci-flat and Koehler so that they are gravitational instantons. Also exotic smoothness structure of certain R4 determines realistic value of the cosmological constant, neutrino masses and some parameters of inflation. The smoothness is used to explore quantum regime of gravity via operator algebras and Riemannian curvature it generates.

https://arxiv.org/abs/1601.06436
https://arxiv.org/abs/1709.03314
https://arxiv.org/abs/1811.04464

Speaker: Jerzy Krol (University of Silesia)

JKSlajdsBEYOND.pdf