Claus Lämmerzahl (Sunday, 13:30 – 14:30)
ZARM (Zentrum für angewandte Raumfahrttechnologie und Mikrogravitation), Universität Bremen
How to search for quantum gravity effects
The first part of the talk is a short overview over the experimental status of the principles and consequences of standard physics where emphasis is laid on gravity and quantum experiments. The experiments are structured according to a constructive axiomatic way to establish standard physics as encoded in Einstein’s GR and the equations of motion for particles and fields. In the second part of the talk this analysis then is taken to give a guide for a structured search for effects related to quantum gravity theories.
Marco Genovese (Sunday, 14:30 – 15:30)
INRIM (Istituto Nazionale di Ricerca Metrologica), Torino
Toward testing quantum gravity on an optical bench
The aim of building a theory unifying general relativity and quantum mechanics, the so called quantum gravity, has been a key element in theoretical physics research for the last 60 years. Several attempts in this sense have been considered, some of them with huge efforts in term of work of hundreds of scientists. However, for many years no testable prediction emerged from these studies. In the last few years this common wisdom was challenged. A first series of testable proposals concerned photons propagating on cosmological distances, with the problem of extracting QG effects from a limited (uncontrollable) observational sample affected by various propagation effects. More recently, effects in interferometers connected to non-commutativity of position variables in different directions were considered both for cavities with microresonators and two coupled interferometers, the so called “holometer”. In particular this last idea led to build a double 40 m interferometer at Fermilab.
In this talk, we present a work demonstrating how the use of quantum correlated light beams in coupled interferometers could lead to significant improvements allowing an actual simplification of the experimental apparatuses to probe the non-commutativity of position variables, prompting the possibility of testing QG in experimental configurations affordable in a traditional quantum optics laboratory with current technology.
Antonio Di Domenico (Sunday, 16:00 – 17:00)
Dipartimento di Fisica, Università degli Studi di Roma “La Sapienza”
Precision tests of CPT symmetry with entangled neutral K mesons in the search for quantum gravity effects
Even though CPT symmetry appears to be experimentally respected in Nature, with a very solid theoretical foundation in the well known CPT theorem, tiny CPT violation effects could be justified in the framework of a quantum theory of gravity with non trivial space-time topologies, in some cases implying a breaking of the Lorentz symmetry or a loss of coherence in single and entangled quantum states.
Entangled neutral K mesons produced in phi meson decays constitute a very special quantum system, which demonstrate, in the most impressive manner, a number of spectacular quantum phenomena. This system appears specially suited for testing the basic principles of Quantum Mechanics and CPT symmetry, thanks to its extreme sensitivity to possible CPT violation and decoherence effects and the subtle interplay between entanglement and discrete symmetries.
So far no deviation from the expectations of CPT symmetry and Quantum Mechanics is observed, while the precision of the measurements, in some cases, reaches the interesting Planck scale region, where CPT violation effects driven by quantum gravity might show up.
Prospects for this kind of experimental studies with the KLOE-2 experiment at the DAFNE facility will be presented.
Pavel Mnev (Sunday, 17:00 – 18:00)
Steklov Institute of Mathematics, St. Petersburg
Cellular BV-BFV-BF theory
We will introduce the cellular version of BF theory and explain how it fits into symplectic cohomological (“BF-BFV”) quantization programme. Partition functions are given by finite-dimensional integrals, satisfy Segal-like gluing property, are invariant with respect to cellular aggregations (which play the role of Wilson’s renormalization flow) and satisfy BV quantum master equation modified by a boundary term. Partition functions can be expressed in terms of torsions and the data of rational homotopy type; they also contain a mod 16 phase – a model for the eta invariant appearing in the phase of Chern-Simons partition function. This is a report on joint work with A. S. Cattaneo and N. Reshetikhin.
George Savvidy (Sunday, 19:00 – 19:30)
Demokritos National Research Centre
Extension of the Poincaré Group and of Yang-Mills fields
We constructed an extension of the Poincaré group which involves a mixture of internal and space-time symmetries. The resulting group is an extension of the Poincaré (superPoincaré) group with infinitely many generators which carry internal and space-time indices. We constructed a massless irreducible representations, which are divided into longitudinal and transversal representations. We suggest an extension of the gauge principle which includes non-Abelian tensor gauge fields. The proposed extension of Yang-Mills theory is essentially based on the above extension of the Poincaré algebra.
Edwin Beggs (Monday, 16:00 – 17:00)
Department of Mathematics, Swansea University
Semiquantisation and Poisson-Riemannian Geometry
We study noncommutative bundles and Riemannian geometry at the semiclassical level of first order in a deformation parameter λ, using a functorial approach. The data for quantisation of the cotangent bundle is known to be a Poisson structure and Poisson preconnection and we now show that this data defines to a functor Q from the monoidal category of classical vector bundles equipped with connections to the monodial category of bimodules equipped with bimodule connections over the quantised algebra. We adapt this functor to quantise the wedge product of the exterior algebra and in the Riemannian case, the metric and the Levi-Civita connection. Full metric compatibility requires vanishing of an obstruction in the classical data, expressed in terms of a generalised Ricci 2-form R, without which our quantum Levi-Civita connection is still the best possible. We apply the theory to the Schwarzschild black hole and to Riemann surfaces as examples, as well as verifying our results on the 2D bicrossproduct model quantum spacetime. The quantized Schwarzschild black-hole in particular has features similar to those encountered in q-deformed models, notably the necessity of nonassociativity of any rotationally invariant quantum differential calculus of classical dimensions.
Leonardo Castellani (Monday, 17:00 – 18:00)
Dipartimento di Scienze e Innovazione Tecnologica, Università degli Studi del Piemonte Orientale
Nonassociativity emerging from higher form gauge fields
We show that geometric theories with p-form gauge fields have a nonassociative symmetry structure, extending an underlying Lie algebra. This nonassociativity is controlled by the same Chevalley-Eilenberg cohomology that classifies free differential algebras, p-form generalizations of Cartan-Maurer equations. A possible relation with flux backgrounds of closed string theory is pointed out.
Joanna Luc (Monday, 18:50 – 19:10)
Slow-roll approximation in classical and quantum cosmology
Inflationary epoch is one of the most important elements of modern theories of early universe. It could be modelled by some scalar field evolving in a potential dependent on it. For most cases solving equations of motions for this model is impossible without doing some approximations. In my paper I consider slow-roll approximation, which neglects the most slowly changing terms in these equations. This problem is already solved for the classical case to arbitrary order. However, the same method could be also used for equations which include corrections from loop quantum cosmology (LQC). In this case there exist only solutions to the first order. I extend them to the second order. Obtained results could be used to calculate spectral indices, which might be compared with Planck data.
Tomasz Trzesniewski (Monday, 19:10 – 19:30)
University of Wroclaw
A study of the Curved Field Space Theory
In the recent years, phase spaces with nontrivial geometry have become an interesting topic of research, especially in the context of quantum gravity. In the same vein we consider a possible extension of the field theory formalism to the case of fields with a curved phase space for the field values. In particular, we study the example of a scalar field with the spherical field phase space. Exploring this model with the help of the perturbative methods we encounter a variety of effects known from the quantum gravity research, including algebra deformations, a generalization of the uncertainty relation, a shifting of the vacuum energy and extra poles in the propagator, with the modified speed of propagation.
Walter van Suijlekom (Tuesday, 13:30 – 14:30)
Institute for Mathematics, Astrophysics and Particle Physics, Radboud Universiteit, Nijmegen
Grand Unification in the Spectral Pati-Salam Model
We analyze the running at one-loop of the gauge couplings in the spectral Pati-Salam model that was derived in the framework of noncommutative geometry. There are a few different scenarios for the scalar particle content which are determined by the precise structure of the finite noncommutative space. We consider these different scenarios and establish for all of them unification of the Pati-Salam gauge couplings. The boundary conditions are set by the usual RG flow for the Standard Model couplings at an intermediate mass scale at which the Pati-Salam symmetry is broken.
Ralph Blumenhagen (Tuesday, 16:00 – 17:00)
Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), München
From Double Field Theory to Large Field Inflation
Observation of the CMB by Planck and BICEP have the potentialto detect primordial gravitational waves. Such a success would imply large field inflation with a mass scale at the GUT scale. Realizing such models in a UV completetheory of quantum gravity is challenging. An approach to realise thepromising scenario of F-term axion monodromy inflation is presented that is basedon the scalar potential induced by compactifying Double Field Theory on Calabi-Yau manifoldswith geometric and non-geometric fluxes turned on.
Catherine Meusburger (Tuesday, 17:00 – 18:00)
Department Mathematik, Friedrich-Alexander-Universität Erlangen-Nürnberg
Hopf algebra gauge theories and Kitaev models
We explain how the notion of a lattice gauge theory on a graph can be generalised to a lattice gauge theory with values in a ribbon Hopf algebra. We give an axiomatic description of such Hopf algebra gauge theories and show that the result coincides with the algebra obtained by combinatorial quantisation of Chern-Simons gauge theory. We explain how
the resulting gauge theory is related to Kitaev’s lattice models in the case of a Drinfeld double of a semisimple Hopf algebra.
Piotr M. Hajac / Mariusz Tobolski (Tuesday, 18:30 – 19:00)
IMPAN / University of Warsaw
There and back again: from the Borsuk-Ulam theorem to quantum spaces
Assuming that both temperature and pressure are continuous functions, we can conclude that there are always two antipodal points on Earth with exactly the same pressure and temperature. This is the two-dimensional version of the celebrated Borsuk-Ulam Theorem which states that for any continuous map from the n-dimensional sphere to n-dimensional real Euclidean space there is always a pair of antipodal points on the sphere that are identified by the map. Our quest to unravel topological mysteries in the Middle Earth of quantum spaces will begin with gentle preparations in the Shire of elementary topology. Then, after riding swiftly through the Rohan of C*-algebras and Gelfand-Naimark Theorems and carefully avoiding the Mordor of incomprehensible technicalities, we shall arrive in the Gondor of compact quantum groups acting freely on unital C*-algebras. It is therein that the generalized Borsuk-Ulam-type statements dwell waiting to be proven or disproven. To end with, we will pay tribute to the ancient quantum group SUq(2), and show how the proven non-trivializability of Pflaum’s SUq(2)-principal instanton bundle is a special case of two different noncommutative Borsuk-Ulam-type conjectures. Time permitting, we shall also explain how pulling back associated noncommutative vector bundles allows us to extend the non-trivializability result from the Pflaum quantum instanton bundle to an arbitrary finitely iterated equivariant join of SUq(2) with itself. (Based on joint work with Paul F. Baum, Ludwik Dabrowski and Tomasz Maszczyk.)
Niels Obers (Wednesday, 13:30 – 14:30)
Niels Bohr Institutet, Københavns Universitet
The return of Newton-Cartan spacetime
Newton-Cartan geometry was introduced more than 90 years ago in order to find a geometric formulation of Newtonian gravity. Recently, this geometry (including a novel generalisation that includes torsion) has made its appearance in holography for systems with non-relativistic symmetry and been studied in parallel directly in a non-relativistic field theory context. I will introduce this geometrical framework and show how it naturally appears when making Galilean symmetry local, in the same way that Riemannian geometry and general relativity emerges from making Poincare local. I will subsequently discuss why and how non-relativistic field theories naturally couple to Newton-Cartan geometry and some simple results that follow from this coupling. Finally, I will describe the dynamics of Newton-Cartan geometry and show that it describes Horava-Lifshitz gravity and outline some perspectives that follow from this covariant reformulation.
Georgina Rippon (Wednesday, 15:00 – 16:00)
School of Life & Health Sciences, University of Aston, Birmingham
The Trouble with Girls?: Why Plastic Brains aren’t Breaking Through Glass Ceilings
There is a long history of debate about biological sex differences and their part in determining gender roles, with the ‘biology is destiny’ mantra being used to legitimise imbalances in these roles. The tradition is continuing, with new brain imaging techniques being hailed as sources of evidence of the ‘essential’ differences between men and women, and the concept of ‘hardwiring’ sneaking into popular parlance as a brain-based explanation for all kinds of gender issues. This includes the failure of numerous well-meaning initiatives attempting to address the marked gender imbalances in many areas of achievement, especially science. There are assumptions (not always unspoken) that women don’t succeed in such spheres because they can’t, with rather patronising (sic) references to ‘complementarity‘, ‘vulnerability’ and ‘the natural order of things’.
This talk outlines a model demonstrating how there is indeed a ‘brain problem’. Existing gender stereotypes can and do (mis)construct brain function and even structure, with negative consequences on the education, expectations and achievements of women. But it also highlights the possibilities offered by a greater understanding of how plastic and permeable our brains are, how we can build internal and external defences against “toxic stereotypes” and how the concept of ‘hard-wiring’ can be condemned to the dustbin of neurohistory.
Astrid Eichhorn (Thursday, 14:30 – 15:30)
Department of Physics, Imperial College London
Asymptotically safe quantum gravity
I will discuss the asymptotic safety scenario for quantum gravity, introducing the basic idea and reviewing the evidence that exists for the viability of this model of quantum gravity. I will then focus on more phenomenological questions, and discuss the cosmological constant problem in this setting, as well as the inclusion of dynamical matter in this model of quantum gravity.
Kentaroh Yoshida (Thursday, 15:30 – 16:30)
Department of Physics II, Kyoto University
Towards the gravity/CYBE correspondence
We present a systematic way to consider integrable deformations of the AdS_5 x S^5 superstring. It is based on classical r-matrices satisfying classical Yang-Baxter equation (CYBE).Then a classical r-matrix corresponds to a gravitational solution that describes a deformed AdS_5 x S^5 geometry. In this talk, we present some examples including the Lunin-Maldacena backgrounds for beta deformations of the N=4 super Yang-Mills theory, the Maldacena-Russo backgrounds for non-commutative gauge theories, and Schroedinger spacetimes dual for non-relativistic conformal field theories. If there is time, we will also explain Yang-Baxter deformations of 4D Minkowski spacetime.
Igor Kanatchikov (Thursday, 17:30 – 18:00)
St. Andrews University
Precanonical quantization of gravity: from quantization of differential
forms to the the cosmological spin-connection field and of a possible
fractality of space-time
I outline the precanonical quantization of fields, which is based on quantization of Gerstenhaber algebra of brackets on differential forms found within the De Donder-Weyl Hamiltonian formulation of field theories. The resulting formulation of quantum fields is a Clifford algebraic generalization of quantum mechanics in which all space-time variables enter on an equal footing and the wave functions and operators take values in the Clifford (Dirac) algebra of space-time. The analog of the Schroedinger equation is a Dirac equation with a mass term replaced by the De Donder-Weyl Hamiltonian operator. I sketch the idea of the proof of how the standard QFT appears from precanonical quantization in the limiting case of an infinitesimal “elementary volume” which appears in the representations of differential forms on space-time by dimensionless Dirac matrices. I outline the procedure of precanonical quantization of the Einstein’s gravity in vielbein variables, the way the Einstein equations emerge as the equations on expectation values operators, thus demonstrating the consistency of the approach with the classical limit. I will also discuss some first consequence of the formulation such as the value of the cosmological constant and the Levy-type statistics of the cosmological random spin-connection field which points to a possible fractality of space-time and potential may lead to testable predictions. Based on: arXiv:1407.3101, arXiv:1512.09137, arXiv:1602.01083 and the refs therein.
Stijn van Tongeren (Thursday, 18:00 – 18:30)
Humboldt University Berlin
Drinfeld twisting AdS/CFT
I will explain how both sides of the canonical AdS/CFT duality between maximally supersymmetric Yang-Mills theory and string theory on AdS_5 x S^5 can be deformed by so-called Drinfeld twists, leading to string theory duals to various kinds of noncommutative versions of supersymmetric Yang-Mills theory, including ones of kappa-Minkowski type. As a bonus, in the planar limit these theories are integrable.