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Stefan Floerchinger (University of Jena)23/09/2024, 14:30
The talk reviews how a geometric approach to information theory and the functional renormalization group are closely connected. Information geometry defines distances on spaces of probability distributions, as well as further differential geometric structure like connections or curvature. In the context of field theories one can define on that basis geometrical structure on the space of...
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Gabriel Picanco Costa23/09/2024, 14:50
Using RG methods, I discuss perturbative and non-perturbative fixed points and conformal windows in 4d supersymmetric gauge theories coupled to matter and a superpotential. At weak coupling, I give an overview of perturbative UV and IR fixed points and their corresponding phase diagrams. At strong coupling, I discuss how conformal fixed points and superfield anomalous dimensions are identified...
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Alfiia Mukhaeva23/09/2024, 15:10
We consider a four-dimensional $SU(N_c)$ gauge theory coupled to $N_f$ species of color fermions and $N_f^2$ colorless scalars. Compared to previous studies, we have included all possible trilinar and quartic scalar operators. In the regime where asymptotic freedom is absent, we determine all interacting fixed points using perturbation theory up to three loop in the gauge and two loop in the...
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Aaron Held (Jena University)23/09/2024, 15:30
I present a probabilistic framework to analyse global Renormalization Group Flows in large theory spaces. The framework allows to efficiently find basins of attraction, including fixed points of the linearized flow, as well as novel nonlinear attractors. As a working example, I discuss the gauge, Yukawa, and Higgs sector of the Standard Model of particle physics. I will also comment on...
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Shouryya Ray23/09/2024, 16:20
A Stiefel manifold for $N, p$ integers with $N > p$ is the quotient $\operatorname{SO}(N)/\operatorname{SO}(p)$. In $d = p - 1$ spacetime dimensions (set henceforth $d = 3$), it admits a non-trivial Wess-Zumino--Witten theory. Here, I shall present efforts to study which of these theories admit real fixed points of the renormalisation group flow. I shall work in a Wilsonian implementation,...
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Friederike Ihssen (ITP Heidelberg)23/09/2024, 16:50
The physics of strongly correlated systems offers some of the most intriguing physics challenges such as competing orders or the emergences of dynamical composite degrees of freedom. Often, the resolution of these physics challenges is computationally hard, but can be enormously simplified by its formulation in the dynamical degrees of freedom and within an expansion about the physical ground...
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Franz Richard Sattler23/09/2024, 17:20
I report on technical advancements which are geared towards locating the conjectured critical endpoint of QCD using the functional renormalization group. Its use allows to access directly the high-density region, as this approach does not suffer from the sign problem of lattice QCD. In our first-principles setup, one can systematically identify and include all relevant physical degrees of...
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Marta Picciau23/09/2024, 17:40
We propose relativistic Luttinger fermions as a new ingredient for the construction of fundamental quantum field theories. We construct the corresponding Clifford algebra and the spin metric for relativistic invariance of the action using the spin-base invariant formalism. The corresponding minimal spinor has 32 complex components, matching with the degrees of freedom of a standard-model...
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Jean Paul Ebran24/09/2024, 16:40
The atomic nucleus is a complex system : it is made of composite degrees of freedom strongly coupled by their (strong and electroweak) interactions and hosts a bunch of emergent behaviors, e.g. deformations as well as superfluid and molecular instabilities. Nuclear structure physics endeavors a robust and accurate description of the way an arbitrary number of nucleons self-organizes and gets...
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Laura Batini24/09/2024, 17:10
In this talk, I will explore the dissipation rate of a scalar field near the phase transition and within the ordered phase, focusing on systems that fall under the universality class of Model A. Our approach employs a dynamical field theory framework, where we perform a leading-order expansion of the effective action in terms of field gradients while retaining full field dependence. I will...
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Carlos Contreras24/09/2024, 17:40
In this talk we extend our recent non perturbative functional renormalization group analysis of Reggeon Field Theory to the interactions of Pomeron/Odderon fields and two Pomeron fields. We establish the existence of a fixed point and its universal properties. This analysis, allows to connect the nonperturbative infrared region (large transverse distances) with the UV region of small...
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Gudrun Hiller (Technische Universitaet Dortmund (DE))25/09/2024, 14:30
I report on recent developments in model building and flavor phenomenology that is using RG-techniques and UV-safety.
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รlvaro Pastor Gutiรฉrrez25/09/2024, 14:50
We study the interplay of colour confinement and dynamical symmetry breaking dynamics in gauge theories coupled to fermions. We provide a first-principles analysis employing the functional Renormalisation Group. We analyse the landscape of theories spanning from QCD-like to the conformal window, showing evidence for walking dynamics. Employing bosonisation techniques we access fundamental...
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Daniele Rizzo (NCBJ)25/09/2024, 15:10
Certain types of large-$N$ gauge theories coupled to matter offer interacting UV fixed points that are under strict perturbative control, beyond the paradigm of asymptotic freedom. In this work, we derive and investigate functional RG equations for the quantum effective potential of the theory to leading order in a derivative expansion. We thereby find the RG flows, fixed points, and scaling...
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Manuel Reichert25/09/2024, 15:30
Over the past decades, the asymptotic safety scenario has matured into a viable contender for a consistent theory of quantum gravity. Recently, the existence of a fixed point and a well-behaved graviton propagator were for the first time confirmed in a direct Lorentzian computation based on running spectral functions. I will detail the latest results in the computation of graviton spectral...
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Nikolaos Tetradis (National and Kapodistrian University of Athens (GR))25/09/2024, 16:20
I discuss the evolution of entanglement entropy for a massless field within a spherical region in an expanding background. The formalism is applied to the inflationary period and the subsequent era of radiation domination, starting from the Bunch-Davies vacuum. Each field mode evolves towards a squeezed state upon horizon exit during inflation, with additional squeezing when radiation...
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Gergely Fejos (Eรถtvรถs University Budapest)25/09/2024, 16:50
Renormalization group flows of the Ginzburg-Landau potential of chiral symmetry restoration are calculated for a general number of quark flavors (N_f), with the inclusion of all possible (perturbatively) relevant and marginal operators in d = 3 spatial dimensions. We find new, potentially infrared stable fixed points spanned throughout the entire N_f range. By conjecturing that the thermal...
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Rui Wen25/09/2024, 17:20
We improve the $N_f=2+1$ QCD theory within the functional renormalization group (fRG) approach at finite temperature and chemical potential. Starting from the gluon and quark degrees of freedom in the perturbative high-energy regime, we systematically integrate out quantum fluctuations towards the mesons and baryons degrees of freedom in the low-energy regime with dynamical hadronization. The...
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Johannes Roth25/09/2024, 17:40
In this talk, I will give an overview of the universal critical dynamics at the chiral phase transition of two-flavor QCD in the chiral limit. I will review the argument by Rajagopal and Wilczek of the associated dynamic universality class being "Model G" from the Halperin-Hohenberg classification. To extract dynamic universal quantities, we use a novel formulation of the functional...
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Tim Morris (Southampton University)26/09/2024, 14:30
We show that in the local potential approximation of the functional renormalization group, and in the f(R) approximation to asymptotically safe gravity, a combination of Sturm-Liouville and WKB methods allows for an exact analytical solution for scaling dimensions of highly irrelevant operators. The results shed light on properties of these approximations and in particular on recent numerical...
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Mikhail Altaisky26/09/2024, 14:50
Following the paper M. Altaisky Phys. Rev. D 93 (2016) 105043, we develop a new approach to the renormalization group, where the effective action functional $\Gamma_A[\phi]$ is a sum of all fluctuations of scales from the size of the system ($L$) down to the scale of observation ($A$). It is shown that the renormalization flow equation of the type $ \frac{\partial \Gamma_A}{\partial \ln A} =...
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Sara Rufrano Aliberti26/09/2024, 15:10
There are still many unanswered questions from General Relativity, such as black holes singularity and dark energy: these puzzles have led to the development of extended theories of gravity. One approach to modifying General Relativity consists of adding new degrees of freedom, such vector fields, resulting in the so-called Generalized Proca theories. In order to determine whether these...
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Nobuyoshi Ohta (Kinki University)26/09/2024, 15:30
In the renormalization group approach, it is known that inessential
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couplings could be removed by the field redefinitions. Recently it is
pointed out that the quadratic curvature terms fall into this class of
operators, and next cubic term is irrelevant. This suggests that the
Einstein and cosmological term is enough to define asymptotically safe
quantum gravity for pure gravity. Here we... -
Christof Wetterich (Heidelberg University)
We propose to adapt the precise definition of the flowing effective action in order to obtain a functional flow equation with simple properties close to physical intuition. The simplified flow equa- tion is invariant under local gauge transformations and suitable for both euclidean and Minkowski signature and analytic continuation. The cutoff always removes fluctuations close to zeros of the...
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