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Oleg Antipin10/06/2019, 09:15
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Luca Zambelli10/06/2019, 10:00
The renormalization-group flow of Higgs-Yukawa models with a non-Abelian gauge sector has been studied for several decades by adopting two simplifying assumptions: that the theory is perturbatively renormalizable and that all mass terms are negligible at high energies. Within this theoretical framework, total asymptotic freedom appears to be a rare phenomenon which severely constrains the...
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Augusto Sagnotti (PI)10/06/2019, 11:15
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Damiano Anselmi (PI)10/06/2019, 12:00
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Ergin Sezgin10/06/2019, 14:15
I will describe the salient features of higher spin theories as gauge theories based on infinite dimensional extension of (A)dS algebras, a la Vasiliev. The fully nonlinear equations of motion are formulated compactly on a product of spacetime with a noncommutative twistor space. I will highlight a powerful method for finding exact solutions of the theory which crucially employs the twistor...
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Roberto Percacci10/06/2019, 15:00
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Fabrizio Nesti (TS)10/06/2019, 16:15
I describe the efforts to implement a theory of massive graviton and how the request for a weakly coupled phase leads to the need to break not only general covariance, but also Lorentz symmetry. Hamiltonian analysis of the nonperturbative degrees of freedom, as well as cosmology and exact solutions generalizing the Schwarzschild one are described.
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Manuel Reichert10/06/2019, 17:00
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Carlos Nieto10/06/2019, 17:35
I will discuss the fate of the U(1) gauge coupling under the inclusion of vector-like fermions in the standard model. Then, motivated by results on quantum gravity contributions to the running of gauge and Yukawa couplings, I talk about the effect of simple but general corrections on the running of those couplings from the EW to large enough energy scales. One of our goals is to have an...
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Martin Reuter11/06/2019, 09:00
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Tim Morris11/06/2019, 09:45
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...
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Jan Pawlowski11/06/2019, 11:00
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Daniel Litim11/06/2019, 11:45
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Renate Loll11/06/2019, 14:00
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Astrid Eichhorn11/06/2019, 14:45
Asymptotic safety, i.e., scale invariance in the ultraviolet, is a compelling proposal for the nature of fundamental interactions. Understanding its phenomenological consequences is a critical challenge, as any physical theory requires testing through confrontation with observations and experiments. In this talk I will discuss potential consequences of asymptotic safety for (Beyond) Standard...
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Nobuyoshi Ohta11/06/2019, 16:00
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Carlo Pagani11/06/2019, 16:45
We consider the theory space as a manifold whose coordinates are given by the couplings appearing in the effective action. We discuss how to introduce connections on this theory space in the framework of the functional renormalization group (FRG). Finally, we discuss possible developments and limitations of this formalism and how to overcome such difficulties in the FRG setting.
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Kevin Falls11/06/2019, 17:30
I will discuss whether or not scalar-tensor theories in the Einstein and Jordan frames are equivalent once quantum corrections are taken into account. To understand this problem it is crucial to carefully define the path integral measure that arises in the quantization of the equivalent classical theories. Generically two measures will differ if the spacetime metrics in the two theories are...
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Saverio Lombardi (INAF-OAR and ASI Science Data Center, Rome, Italy)12/06/2019, 09:00
Very-high energy (VHE, E>~50 GeV) gamma rays of cosmic origin can reveal unique information on paramount open issues of fundamental physics while also providing a complementary probe to laboratory experiments and particle accelerators. In fact, the search for VHE gamma-ray signatures from the annihilation or decay of dark matter (DM) particles is a promising method for identifying DM,...
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Mairi Sakellariadou12/06/2019, 09:45
The recent discoveries of gravitational waves (GWs)
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from the LIGO and Virgo interferometers opened a new
era in GWs as well as multi-messenger astronomy, and offered new ways to test gravitational theories beyond Einstein's theory of General Relativity.
Very recently it has been also shown how nonperturbative quantum gravity (QG) can affect the GW luminosity distance associated with the long... -
Vasilios Zarikas12/06/2019, 10:30
Infrared corrections that arise in some theoretical attempts to
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understand Quantum Gravity may be the solution to one tantalizing problem of modern physics. Recently a novel Asymptotically Safe cosmology suggested a simple and attractive mechanism towards resolving naturally the structure
of dark energy and its associated cosmic coincidence problem. The novel idea is that the recent... -
Kirill Krasnov12/06/2019, 11:25
It has been suggested in the past (by several different authors) that the Standard Model gauge group can be combined with Lorentz group. If this is done, all fermions of a single generation of the SM receive the interpretation of components of a single spinor of a pseudo-orthogonal group Spin(p,q) of dimension p+q=14. There are only two possibilities that do not lead to the fermion doubling...
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Ludwik Dabrowski12/06/2019, 12:10
All the fundamental matter particles are fermions and correspond
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to spinor fields.
They arise as projective representation of the rotations
and (pseudo) orthogonal groups, and their installation on curved
space-times requires introducing of particular geometric structures.
I will discuss some of their surprising and nontrivial aspects
including the seldom discussed subtle issue of general... -
Bertrand Delamotte12/06/2019, 14:25
The O(N) models are probably the most studied field theories. Everything is supposed to be known about their symmetric and symmetry broken phases as well as their critical behavior. Many analytical methods were born here and it is the textbook example for both the $\epsilon=4-d$ and the
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large-$N$ expansions. We nevertheless show that several
renormalization group fixed points of this model... -
Bianca Dittrich12/06/2019, 15:10
I give a review of recent work on establishing holographic duals for quasi-local boundaries in 3D perturbative and non-perturbative gravity, as well as its extension to 4D gravity.
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In particular I will show how holographic duals can be constructed as effective actions for geometric boundary observables. I will then connect this work with more standard holographic considerations at asymptotic... -
Steffen Gielen12/06/2019, 16:25
General Relativity is conventionally formulated as a theory with gauge invariance under the diffeomorphism group of general coordinate transformations, but there are locally equivalent formulations in terms of either a larger (additional local conformal invariance) or smaller (only "special" diffeomorphisms) group of symmetries. Other formulations with the same number of gauge generators, but...
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Stefan Lippoldt12/06/2019, 17:10
In this talk I will point out some properties of general relativity, which are particularly important for the FRG. First I am going to consider the special structure of the gauge symmetry in gravity leading to a discussion of gauge invariance within asymptotic safety. Second I will highlight some consequences of boundaries in path integrals arising, e.g., when restricting the path integral to...
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