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String Journal Club
String Journal Club
Time: 01/11/201912:30  14:00
Location: C4.278, Science Park 904, Amsterdam
Description: Weekly string theory journal club with paper discussion and talk by a group member (this week: guest speaker). Papers can be posted here.
Talk: Pushkal Shrivastava: A Simple Quantum Test for Smooth Horizons
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Cosmology Seminar: Kfir Blum
Cosmology Seminar: Kfir Blum
Time: 04/11/201911:00  12:00
Location: C4.174, Science Park 904, Amsterdam
Title: Hunting for Ultralight Dark Matter with Galactic Kinematics
Abstract: Bosonic ultralight dark matter (ULDM) would form cored density distributions ("solitons") at the centre of galactic halos. Numerical simulations found empirical scaling relations between the mass of the halo and the mass of the soliton. We show that the simulations imply specific kinetic energy equilibration and predict that the peak circular velocity, measured at the outskirts of the galaxy, should repeat itself in the central region, providing a rare opportunity to look for or constrain the particle nature of dark matter with minimal gravity alone. Contrasting this prediction to rotation curves of low surfacebrightness galaxies, we show that ULDM with m<10^21eV, which has been invoked as a solution of smallscale puzzles of LCDM, is in tension with the data. We discuss the potential of dynamical modelling of the Milky Way and other systems to probe ULDM up to m ~ 10^19eV in the near future.

GRAPPA Journal Club
GRAPPA Journal Club
Time: 04/11/201913:30  14:30
Location: C4.174, Science Park 904, Amsterdam
Description: Weekly GRAPPA journal club. Papers can be posted here. Lunch is provided.
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String Seminar: Max Zimet
String Seminar: Max Zimet
Time: 05/11/201911:00  12:30
Location: G0.05, Science Park 904, Amsterdam
Title: K3 Metrics from Little String Theory
Abstract: CalabiYau manifolds have played a central role in both string theory and mathematics for decades, but in spite of this no Ricciflat metric on a compact nontoroidal CalabiYau manifold is known. I will discuss a new physicallymotivated approach toward the determination of such metrics for K3 surfaces. The key remaining step is the determination of the BPS spectrum of a little string theory on T^2. I will use string dualities to provide a number of mathematical reformulations of this problem. Finally, I will discuss new approximations to K3 metrics that require only minimal knowledge of this BPS spectrum. (Preseminar at 11:00, talk at 11:30.)

GRAPPA Seminar: Adam Pound
GRAPPA Seminar: Adam Pound
Time: 05/11/201914:00  15:00
Location: C4.278, Science Park 904, Amsterdam
Title: Accurately Modelling ExtremeMassRatio Inspirals: Beyond the Geodesic Approximation
Abstract: Recent observations of gravitational waves represent a remarkable success of our theoretical models of relativistic binaries. However, accurate models are largely restricted to binaries in which the two members have roughly equal masses; for binaries with more disparate masses, modelling is less mature. This is especially relevant for extrememassratio inspirals (EMRIs), in which a stellarmass object orbits a supermassive black hole in a galactic core. EMRIs are uniquely precise probes of black hole spacetimes and they will be key targets for the spacebased detector LISA. They are best modelled by gravitational selfforce theory, in which the smaller object generates a small gravitational perturbation that reacts back on it to exert a "selfforce", accelerating the object away from geodesic motion. For LISA science, we must work to second order in this perturbative treatment. In this talk, I discuss the foundations of selfforce theory, its application to EMRIs, and the current status of first and secondorder models.
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QGI Virtual Seminar: Eva Silverstein
QGI Virtual Seminar: Eva Silverstein
Time: 06/11/201916:00  17:00
Location: C4.278, Science Park 904, Amsterdam
Title: De Sitter Quantum Gravity and Information via T\bar T
Abstract: After briefly reviewing de Sitter models in string theory (including a new class under development), I will highlight basic structural constraints which enter into its holographic description. For the bulk of the talk, I will explain a holographic duality for patches of (A)dS spacetimes obtained from concrete generalizations of the solvable $T\bar T$ deformation, supported by explicit agreement of the energy spectrum on the two sides along with a growing list of matching informationtheoretic quantities. In particular, I will present our recent analysis of subregion dualities, building from new calculations of entanglement entropy which match precisely on both sides of the duality. Along the way, I will comment on novel features of the operator algebras in these systems. These results probe the form of nonlocality (consistently with causality) arising in $T\bar T$ deformed theories, and exhibit the phenomenon of redundant encoding of bulk operators (quantum error correction) in the more realistic case of de Sitter quantum gravity. (Alternatively, it is possible to directly watch here.)
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Nikhef Theory Seminar: Alessandro Sfondrini
Nikhef Theory Seminar: Alessandro Sfondrini
Time: 07/11/201916:00  17:00
Location: H331, Science Park 105, Nikhef, Amsterdam
Title: Exact Holography from the String Worldsheet
Abstract: The talk is meant to be a pedagogical introduction to some recent efforts to probe holography quantitatively. I will focus in particular on new integrability and CFT approaches on the string worldsheet, which I intend to introduce and motivate physically. I will conclude by discussing the outstanding challenges of this program and how I believe that they may be addressed.
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String Journal Club
String Journal Club
Time: 08/11/201912:30  14:00
Location: C4.278, Science Park 904, Amsterdam
Description: Weekly string theory journal club with paper discussion and talk by a group member. Papers can be posted here.
Talk: Max Rota: Holographic Entropy Inequalities

Dutch Cosmology Meeting
Dutch Cosmology Meeting
Time: 08/11/201913:00  17:30
Location: Room Oort 276, Institute Lorentz for Theoretical Physics, Niels Bohrweg 2, Leiden
Brief schedule:
– 13:00  14:00: David Harvey: Testing Dark Matter SelfInteractions with Future AllSky Surveys
– Coffee
– 14:30  15:30: Miguel Zumalacarregui: No LIGO MACHO: Bounds on Primordial Black Holes as Dark Matter from Gravitational Lensing of Supernovae
– 15:30  16:30: Alexander Westphal: Flattened Axion Monodromy Beyond Two Derivatives
– Borell
More details including abstracts can be found (eventually) on the THC website.
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GRAPPA Seminar: Subodh Patil
GRAPPA Seminar: Subodh Patil
Time: 11/11/201911:00  12:00
Location: C4.174, Science Park 904, Amsterdam
Title: Primordial Black Holes, Inflation and Scale Invariance
Abstract: Primordial black holes (PBHs) are generated by peaks in the density contrast after modes reenter the horizon during radiation or matter domination. These peaks are thought to arise from some mechanism that amplifies the twopoint function of curvature perturbations during inflation and can thus be constrained by complimentary observations of smallscale power such as pulsar timing arrays and spectral distortions of the cosmic microwave background. However, in order to obtain such bounds, one needs to make assumptions about the shape of the underlying PBH mass function, typically taken to be monochromatic. The latter presumes sharply peaked spikes in the underlying primordial power spectrum. In this talk, I will discuss theoretical bounds on how fast correlation functions can grow during single field inflation and how these affect presently understood bounds on PBH abundances. Time permitting, I will also discuss work in progress that explores mechanisms to create PBHs from scaleinvariant initial conditions for curvature perturbations.
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String Seminar: Jorge Kurchan
String Seminar: Jorge Kurchan
Time: 12/11/201911:00  12:30
Location: F2.04, Science Park 904, Amsterdam
Title: From Toy Glasses to Toy Black Holes, and Back
Abstract: SYK is a quantum toy model, inspired by spinglasses, of 'strange metals': a system whose excitations are very different from plane waves (quasiparticles). It has zerotemperature entropy and specific heat linear in temperature. A few years ago, Kitaev pointed out that it also saturates a quantum bound to chaos and that this is due to an emergent reparametrization quasiinvariance that dominates its lowenergy physics. All these properties promoted it to being a 'toy' version of black holes and holography. Quasireparametrization invariance is a key property of glassy physics and it appears in a strikingly similar technical context. I will describe this and other 'coincidences', assuming that you know much more about field theory and much less about glasses than I do. (Preseminar at 11:00, talk at 11:30.)
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Cosmology Journal Club
Cosmology Journal Club
Time: 14/11/201910:45  11:45
Location: C4.278, Science Park 904, Amsterdam
Description: Weekly cosmology journal club. Papers can be posted here.
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National Seminar Theoretical HighEnergy Physics: Gui Pimentel
National Seminar Theoretical HighEnergy Physics: Gui Pimentel
Time: 15/11/201910:15  11:15
Location: Z011, Nikhef/CWI, Science Park 123, Amsterdam
Title: The Cosmological Bootstrap
Abstract: In flat space, fourpoint scattering amplitudes at weak coupling can be fully determined from Lorentz symmetry, unitarity and causality. The resulting scattering amplitude depends on model details only through coupling constants and the particle content of the theory. I will show how the analogous story works in the case of inflationary fluctuations. I will present explicit expressions for weakly coupled inflationary three and fourpoint functions, whose shapes depend on the field content of the theory and do not depend on the specific inflationary model as long as the fluctuations minimally break de Sitter symmetry. This "cosmological bootstrap" is a first step towards classifying all possible shapes of primordial nonGaussianity, which can be searched for in experimental data. I will also present results for cosmological correlation functions of spinning fields, where consistency forces us to rediscover many beautiful, universal results about gauge theory and gravity.

Nikhef Colloquium: Vitor Cardoso
Nikhef Colloquium: Vitor Cardoso
Time: 15/11/201911:15  12:15
Location: Z011, Nikhef/CWI, Science Park 123, Amsterdam
Title: Black Holes as a Physics Laboratory
Abstract: The LIGO/Virgo gravitational wave detections, the imaging of a black hole shadow by longbaseline radio interferometry and ever more precise observations across all electromagnetic wavelengths have opened an unprecedented window onto gravity at its strongest. Black holes are the simplest, most compact and physically elusive macroscopic objects in the Universe and play a central role in this new era in physics and astronomy. In this talk, I will describe how black holes can be used to understand foundational questions: Are gravitons massless? Are black holes the simplest possible macroscopic objects? Do event horizons and black holes really exist or is their formation halted by some asyet unknown mechanism? Do singularities arise in our universe as the outcome of violent collisions? Can black holes inform us about the nature of the elusive dark matter?

GW Seminar: Ryan Magee
GW Seminar: Ryan Magee
Time: 15/11/201915:00  16:00
Location: N328, Nikhef, Science Park 105, Amsterdam
Title: Subsolar Mass Black Holes as a Probe of the Dark Matter
Abstract: Advanced LIGO and Advanced Virgo have revealed a rich population of binary black holes and neutron stars, and this has revived interest in the possibility of subsolar mass ultracompact objects. Since astrophysical processes are not expected to produce ultracompact objects below one solar mass, the detection of a subsolarmass ultracompact object could therefore be an indication of new physics. It has been proposed that lowmass black holes could be formed primordially through density fluctuations in the early Universe, or via particulate dark matter with nuclear interactions and/or 'dark' electromagnetism. We discuss results for the first Advanced LIGO searches for subsolar mass ultracompact objects as well as an interpretation of these results for two dark matter models.

National Seminar Theoretical HighEnergy Physics: Oliver Schlotterer
National Seminar Theoretical HighEnergy Physics: Oliver Schlotterer
Time: 15/11/201915:15  16:15
Location: Z011, Nikhef/CWI, Science Park 123, Amsterdam
Title: The Unity of Scattering Amplitudes in Field and String Theories
Abstract: In a variety of recent developments, scattering amplitudes hint at new symmetries of and unexpected connections between physical theories which are otherwise invisible in their conventional description via Feynman diagrams or Lagrangians. Yet, many of these hidden structures are conveniently accessible to string theory where gauge interactions and gravity arise as the lowenergy excitations of open and closed strings. In this talk, I will give an intuitive picture of gravity as a double copy of gauge interactions and extend the web of relations to scalar field theories including chiral Lagrangians for Goldstone bosons. Moreover, many of the string corrections to gauge and gravity amplitudes beyond their pointparticle limit nicely resonate with the fieldtheoretic doublecopy structures. The resulting higherderivative interactions are accompanied by multiple zeta values whose numbertheoretic properties pinpoint the doublecopy pairing of highermassdimension operators.

Live ISS Spacewalk
Live ISS Spacewalk
Time: 15/11/201916:00  18:00
Location: Het Spectrum, Nikhef, Amsterdam
Description: Astronauts aboard the International Space Station will perform a spacewalk to repair the cooling of the AMS particle detector. This will be screened live on the screen with talks by Suzan du Pree and others. In addition, drinks will be served.
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Cosmology Seminar: Scott Melville
Cosmology Seminar: Scott Melville
Time: 18/11/201911:00  12:00
Location: C4.174, Science Park 904, Amsterdam
Title: Staying Positive in the Hunt for New Physics
Abstract: New physics at high energies can leave characteristic imprints on the effective interactions we observe at low energies. By searching for these imprints in our lowenergy experiments, we are able to effectively probe properties of the underlying UV physics (such as locality and unitarity). And vice versa, assuming basic QFT axioms hold at high energies provides a strong theoretical prior which can improve our data analysis in the IR and sometimes even rule out models altogether. These connections between the IR couplings and the underlying UV theory are known as "positivity bounds", and in this talk I will review recent progress in applying them to simple theories on Minkowski space, Horndeski theories of Dark Energy and the Effective Field Theory of Inflation.

GRAPPA Journal Club
GRAPPA Journal Club
Time: 18/11/201913:30  14:30
Location: C4.174, Science Park 904, Amsterdam
Description: Weekly GRAPPA journal club. Papers can be posted here. Lunch is provided.
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GRAPPA Colloquium: Gilles Louppe
GRAPPA Colloquium: Gilles Louppe
Time: 19/11/201910:00  11:00
Location: C1.112, Science Park 904, Amsterdam
Title: Neural LikelihoodFree Inference
Abstract: In many scientific fields such as particle physics, climatology or epidemiology, simulators often provide the best description of realworld phenomena. However, they also lead to challenging inverse problems because the density they implicitly define is often intractable. In this talk, we will present a suite of simulationbased inference techniques (frequentist and bayesian) that go beyond the traditional Approximate Bayesian Computation approach, which typically struggles in a highdimensional setting. We will cover inference methods that use surrogate models based on modern neural networks, including variants of likelihoodratio estimation algorithms, MCMC sampling techniques or probabilistic programming inference engines. We will also show that additional information, such as the joint likelihood ratio and the joint score, can often be extracted from simulators and used to augment the training data for these surrogate models. We will demonstrate that these new techniques are more sample efficient and provide higherfidelity inference than traditional methods.

String Seminar: Jorge Kurchan
String Seminar: Jorge Kurchan
Time: 19/11/201911:00  12:30
Location: G0.05, Science Park 904, Amsterdam
Title: Gravity and Geometrization of Turbulence
Abstract: Fully developed incompressible fluid turbulence is largely considered as the most important unsolved problem of classical physics. Most fluid motions in nature at all scales are turbulent, yet despite centuries of research, we still lack an analytical description and understanding of fluid flows in the nonlinear regime. Experimental and numerical data suggest that turbulence at the inertial range of scales reaches a steady state that exhibits statistical homogeneity and isotropy and is characterized by universal scaling exponents. We will propose a conceptually new viewpoint inspired by black hole dynamics and construct a field theory geometrization of turbulence. Within this framework we will derive an exact analytical formula for the inertial range longitudinal anomalous scalings in agreement with the available numerical and experimental data. We will present new predictions of the formula. (Preseminar at 11:00, talk at 11:30.)
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Cosmology Journal Club
Cosmology Journal Club
Time: 21/11/201911:00  12:00
Location: C4.278, Science Park 904, Amsterdam
Description: Weekly cosmology journal club. Papers can be posted here.

GW/BH Lecture I: Vitor Cardoso
GW/BH Lecture I: Vitor Cardoso
Time: 21/11/201915:00  17:00
Location: D1.110, Science Park 904, Amsterdam
Title: Some Thoughts on Black Holes
Abstract: Black holes are the simplest macroscopic objects one can conceive of and ideal tools to test new physics or even some of the remarkable predictions of General Relativity. In these two lectures, we will discuss wellestablished black hole physics and outline some of the unexplored aspects, perhaps of relevance to gravitationalwave astronomy or to the strengthening of the black hole paradigm.
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GRAPPA Colloquium: Dan Scolnic
GRAPPA Colloquium: Dan Scolnic
Time: 25/11/201911:00  12:00
Location: C4.174, Science Park 904, Amsterdam
Title: New Excitement In Measurements of Dark Energy and The Hubble Constant
Abstract: In this talk, I will present the latest measurements of the expansion rate of the universe as well as its acceleration. I will focus on the use of TypeIa Supernovae, which continue to be an extremely powerful probe of the local universe. I will dive into the Hubble constant tension, now called a ‘crisis’, and give updates about all of the most recent results as well as what to expect within the next six months. I will also go over recent claims attempting to disprove the confirmation of the accelerating universe. I will then discuss the next generation of telescopes and the supernova revolution we should be expecting in the next decade.

GRAPPA Journal Club
GRAPPA Journal Club
Time: 25/11/201913:30  14:30
Location: C4.174, Science Park 904, Amsterdam
Description: Weekly GRAPPA journal club. Papers can be posted here. Lunch is provided.

Celebration for Gianfranco Bertone
Celebration for Gianfranco Bertone
Time: 25/11/201914:30  15:00
Location: C4.174, Science Park 904, Amsterdam
Gianfranco Bertone has been appointed as Professor of Theoretical Astroparticle Physics at UvA. To celebrate this, there will be cakes after the journal club.

GW/BH Lecture II: Vitor Cardoso
GW/BH Lecture II: Vitor Cardoso
Time: 25/11/201915:00  17:00
Location: C4.174, Science Park 904, Amsterdam
Title: Some Thoughts on Black Holes
Abstract: Black holes are the simplest macroscopic objects one can conceive of and ideal tools to test new physics or even some of the remarkable predictions of General Relativity. In these two lectures, we will discuss wellestablished black hole physics and outline some of the unexplored aspects, perhaps of relevance to gravitationalwave astronomy or to the strengthening of the black hole paradigm.
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Cosmology Journal Club
Cosmology Journal Club
Time: 28/11/201911:00  12:00
Location: C4.278, Science Park 904, Amsterdam
Description: Weekly cosmology journal club. Papers can be posted here.
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Dutch Holography Meeting
Dutch Holography Meeting
Time: 29/11/201913:30  18:00
Location: TBA, Utrecht
Brief schedule:
– Tea & coffee
– 14:00  15:15: Suvrat Raju (ICTS, Mumbai): A Canonical View of Holography
– Coffee
– 15:45  17:00: Mert Besken (UvA): Thermalization in 2d CFT and a Proof of Exponentiation of SemiClassical Virasoro Blocks
– Borrel
More details including abstracts can be found (eventually) on the DITP website.
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