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String Journal Club
String Journal Club
Time: 01/09/201712:30  14:00
Location: D1.113, 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: João Gomes: How Holography knows about Uduality

New MSc ThPhys Welcome Event
New MSc ThPhys Welcome Event
Time: 01/09/201715:00  16:00
Location: SILS Lounge (3rd floor), Science Park 904, Amsterdam
Traditional welcome event for the new MSc ThPhys students with presentation of Sander Bais Prizes
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Faculty Colloquium
Faculty Colloquium
Time: 04/09/201710:00  11:00
Location: C1.110, Science Park 904, Amsterdam
Description: Monthly meeting for all employees of the UvA Faculty of Science.
Programme:
10:00 Update by the dean
10:30: Academic highlight: Jayne Birkby (API): Exoplanet Atmospheres in High Resolution
10:45 Coffee
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String Seminar: Manuela Kulaxizi
String Seminar: Manuela Kulaxizi
Time: 05/09/201711:00  12:30
Location: G0.05, Science Park 904, Amsterdam
Title: Bulk Phase Shift and Einstein Gravity
Abstract: The bulk phase shift, related to a CFT fourpoint function, describes twototwo scattering at fixed impact parameter in the dual AdS spacetime. We describe its properties for a generic CFT and then focus on large N CFTs with classical bulk duals. We compute the bulk phase shift for vector operators using Regge theory. We use causality and unitarity to put bounds on the bulk phase shift. The resulting constraints bound threepoint functions of two vector operators and the stress tensor in terms of the gap of the theory. Similar bounds should hold for any spinning operator in a CFT. Holographically this implies that in a classical gravitational theory any nonminimal coupling to the graviton, as well as any other particle with spin greater than or equal to two, is suppressed by the mass of higher spin particles. (Preseminar at 11:00, talk at 11:30.)
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Cosmology Journal Club
Cosmology Journal Club
Time: 07/09/201711:00  12:00
Location: C4.278, Science Park 904, Amsterdam
Description: Weekly cosmology journal club. Papers can be posted here.
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String Journal Club
String Journal Club
Time: 08/09/201712:30  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: Robert Jefferson: Circuit Complexity in QFT
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Additional String Seminar: Patricio Salgado
Additional String Seminar: Patricio Salgado
Time: 11/09/201711:00  12:00
Location: C4.278, Science Park 904, Amsterdam
Title: Geometric Actions for ThreeDimensional Gravity
Abstract: The solution space of threedimensional asymptotically antide Sitter or flat Einstein gravity is given by the coadjoint representation of two copies of the Virasoro group in the former and the centrally extended BMS3 group in the latter case. Dynamical actions that control these solution spaces are usually constructed by starting from the ChernSimons formulation and imposing all boundary conditions. In this note, an alternative route is followed. We study in detail how to derive these actions from a grouptheoretical viewpoint by constructing geometric actions for each of the coadjoint orbits, including the appropriate Hamiltonians. We briefly sketch relevant generalizations and potential applications beyond threedimensional gravity.

GRAPPA Journal Club
GRAPPA Journal Club
Time: 11/09/201713:30  14:30
Location: C4.174, Science Park 904, Amsterdam
Description: Weekly GRAPPA journal club. Papers can be posted here.
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String Seminar: Shira Chapman
String Seminar: Shira Chapman
Time: 12/09/201711:00  12:30
Location: G0.05, Science Park 904, Amsterdam
Title: Towards Complexity for Quantum Field Theory States
Abstract: I will review the concept of quantum complexity of a state and the related holographic conjectures. I will then describe our proposal for defining the complexity in free scalar field theories for Gaussian states based on the FubiniStudy metric. Minimizing the circuit length according to this proposal with respect to momentum preserving quadratic generators which form su(1,1) algebras gives rise to a beautiful geometric picture where circuits are represented as trajectories on a product space of hyperbolic planes with minimal complexity circuits corresponding to geodesic lines. Despite working with quantum field theories far outside the regime where Einstein gravity duals exist, we find striking similarities between our results and the two holographic complexity proposals. If time permits, I will describe additional developments related to the complexity of thermofield double states and its time dependence. (Preseminar at 11:00, talk at 11:30.)
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Cosmology Journal Club
Cosmology Journal Club
Time: 14/09/201711:00  12:00
Location: C4.278, Science Park 904, Amsterdam
Description: Weekly cosmology journal club. Papers can be posted here.
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Additional GRAPPA Seminar: Ankit Beniwal
Additional GRAPPA Seminar: Ankit Beniwal
Time: 15/09/201711:00  12:00
Location: C4.278, Science Park 904, Amsterdam
Title: Signals from a Scalar Singlet Electroweak Baryogenesis
Abstract: In this talk, I will present our study of the scalar singlet model. In particular, I will discuss the potential probes for electroweak baryogenesis in this model via collider searches, gravitational wave and direct dark matter detection signals. I will show that a large portion of the model parameter space exists where the observation of gravitational waves would allow detection while the indirect collider searches would not. This will motivate my ongoing study of the extended scalar singlet model with a fermion dark matter candidate.

String Journal Club
String Journal Club
Time: 15/09/201712:30  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: Manus Visser: Thermodynamics of Causal Diamonds in (A)dS
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Cosmology Seminar: Evangelos Sfakianakis
Cosmology Seminar: Evangelos Sfakianakis
Time: 18/09/201711:00  12:00
Location: C4.174, Science Park 904, Amsterdam
Title: Preheating After Multifield Inflation with Nonminimal Couplings
Abstract: Multifield models of inflation with nonminimal couplings are in excellent agreement with the observational results from Planck. It is thus imperative that the preheating behavior of these models is analyzed if one wishes to connect any viable inflationary proposal to the hot Big Bang.
I will describe the strong singlefield attractor behavior that exists during inflation in these models and how it generically persists after the end of inflation, thereby avoiding the "dephasing" that can occur in multifield models. This can lead to efficient transfer of energy from the oscillating inflaton field(s) to coupled fluctuations. A doublycovariant formalism can be used for studying such resonances and identifing several features of preheating specific to the nonminimal couplings, including effects that arise from the nontrivial fieldspace manifold.
I will describe the resonance structure in these models and distinguish three regimes based on the size of the nonminimal coupling: small, intermediate and large. The intermediate and large regimes have the same CMB observables, but drastically different preheating behavior.

GRAPPA Journal Club
GRAPPA Journal Club
Time: 18/09/201713:30  14:30
Location: C4.174, Science Park 904, Amsterdam
Description: Weekly GRAPPA journal club. Papers can be posted here.

Additional String Seminar: Cobi Sonnenschein
Additional String Seminar: Cobi Sonnenschein
Time: 18/09/201714:30  15:30
Location: C4.174, Science Park 904, Amsterdam
Title: The Decay Width of Stringy Hadrons
Abstract: I will start with briefly describing the HISH ( Holography Inspired Hadronic String) model and reviewing the fits of the spectra of mesons, baryons, glueballs and exotic hadrons.
I will present the determination of the hadron strong decay widths. The main decay mechanism is that of a string splitting into two strings. The corresponding total decay width behaves as Γ = π/2 A T L where T and L are the tension and length of the string and A is a dimensionless universal constant. The partial width of a given decay mode is given by Γ_i/Γ = Φ_i exp(−2π C m^2_{sep} / T ) where Φ_i is a phase space factor, m_{sep} is the mass of the "quark" and "antiquark" created at the splitting point, and C is a dimensionless coefficient close to unity.
I will show the fits of the theoretical results to experimental data for mesons and baryons. I will examine both the linearity in L and the exponential suppression factor. The linearity was found to agree with the data well for mesons but less for baryons. The extracted coefficient for mesons A = 0.095 ± 0.015 is indeed quite universal. The exponential suppression was applied to both strong and radiative decays. I will discuss the relation with string fragmentation and jet formation. I will extract the quarkdiquark structure of baryons from their decays. A stringy mechanism for Zweig suppressed decays of quarkonia will be proposed and will be shown to reproduce the decay width of Υ states. The dependence of the width on spin and flavor symmetry will be discussed. We further apply this model to the decays of glueballs and exotic hadrons.
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String Seminar: Marco Baggio
String Seminar: Marco Baggio
Time: 19/09/201711:00  12:30
Location: G0.05, Science Park 904, Amsterdam
Title: Conformal Manifolds in Three Dimensions
Abstract: In this talk, I describe a onedimensional complex conformal manifold that characterizes the infrared dynamics of a threedimensional N = 2 supersymmetric theory of three chiral superfields with a cubic superpotential. The manifold of fixed points interpolates between the wellknown XYZ model and three decoupled copies of the critical WessZumino model. The resulting family of CFTs enjoys a duality group of order 24, which puts strong constraints on the operator spectrum, OPE coefficients and the global topology of the conformal manifold. I use the 4 − epsilon expansion as well as numerical conformal bootstrap methods to verify the predictions from duality and calculate the conformal dimensions and OPE coefficients of lowlying operators. (Preseminar at 11:00, talk at 11:30.)
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Cosmology Journal Club
Cosmology Journal Club
Time: 21/09/201711:00  12:00
Location: C4.278, Science Park 904, Amsterdam
Description: Weekly cosmology journal club. Papers can be posted here.

IoP Colloquium: Jeremy Butterfield
IoP Colloquium: Jeremy Butterfield
Time: 21/09/201716:00  17:00
Location: C1.110, Science Park 904, Amsterdam
Title: A Philosopher's Perspective on Multiverse Proposals
Abstract:: This talk will survey, from the perspective of a philosopher of physics, three very different speculations that go by the name of 'multiverse'. They are: (i) the cosmological multiverse, derived from modern cosmology; (ii) the many worlds of the Everettian approach to interpreting quantum theory; and (iii) the idea of all logically possible worlds, from a tradition in logic and philosophy that goes back to Leibniz. Though all three conceptions are very speculative and come in various versions, there are some robust connections between them.
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API Talk: Cosimo Bambi
API Talk: Cosimo Bambi
Time: 22/09/201711:00  12:00
Location: C4.174, Science Park 904, Amsterdam
Title: Testing the Kerr Black Hole Hypothesis with relxill_nk
Abstract: Astrophysical black hole candidates are thought to be the Kerr black holes of general relativity. However, macroscopic deviations from the Kerr background are predicted by a number of scenarios beyond Einstein's gravity. Xray reflection spectroscopy can be a powerful tool to probe the strong gravity region of these objects and test the Kerr black hole hypothesis. Here I briefly review the state of the art of this line of research and I present some preliminary constraints on possible deviations from the Kerr metric obtained with the new Xray reflection model relxill_nk, and XMMNewton, NuSTAR and Swift data of the supermassive black hole in 1H0707495.

String Journal Club
String Journal Club
Time: 22/09/201712:30  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: Alexandre Belin: Quantum Corrections to Holographic Entanglement Entropy
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GRAPPA Journal Club
GRAPPA Journal Club
Time: 25/09/201713:30  14:30
Location: C4.174, Science Park 904, Amsterdam
Description: Weekly GRAPPA journal club. Papers can be posted here.
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String Seminar: Harvey Reall
String Seminar: Harvey Reall
Time: 26/09/201711:10  12:30
Location: TBC
Title: TBA
Abstract: TBA (Preseminar at 11:10, talk at 11:30.)
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String Journal Club
String Journal Club
Time: 27/09/201712:30  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: Francesca Ferrari: TBA
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Cosmology Journal Club
Cosmology Journal Club
Time: 28/09/201711:00  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: 29/09/201713:30  18:00
Location: Universiteit Leiden
Brief schedule:
Premeeting tea & coffee
14:15  15:15: Nikolay Bobev (Leuven): RG Flows Across Dimensions and Holography
15h45  17:00: Nabil Iqbal (Durham): Generalized global symmetries and holography
Borrel with snacks and drinks
More details including abstracts can be found on the DITP website.
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