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Gerald Dunne10/09/2024, 09:30
Resurgent asymptotics unifies perturbative and non-perturbative expansions into a single object, a trans-series, thereby revealing a surprisingly deep network of relations between perturbative and non-perturbative physics. This is a general mathematical formalism with roots in work of Stokes, Dingle and Ecalle, and which has many applications in physics. I will describe the basic ideas...
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Syo Kamata10/09/2024, 10:15
We consider exact WKB analysis to a ${\cal PT}$ symmetric quantum mechanics defined by the potential, $V(x) = \omega^2 x^2 + g x^2(i x)^{\varepsilon=2}$ with $\omega \in {\mathbb R}_{\ge 0}$, $g \in {\mathbb R} _{> 0}$. We in particular aim to verify a conjecture proposed by Ai-Bender-Sarkar (ABS), that pertains to a relation between $D$-dimensional ${\cal PT}$-symmetric theories and analytic...
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Carl M. Bender10/09/2024, 11:15
Schroedingerʼs equation is a local differential equation and boundary conditions are required to determine the solution uniquely. Depending on the choice of boundary conditions, a given Hamiltonian may describe several different physically observable phases, each exhibiting its own characteristic global symmetry.
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Micheline Soley10/09/2024, 13:30
We demonstrate that reflectionless scattering mode (RSM) theory can be used to reveal the existence of long-sought-after quantum mechanical parity-time reversal (PT) symmetry behavior in standard ultracold-atom scattering experiments. In addition, we demonstrate the applicability of RSM theory to ultracold chemical reactions, a discovery which opens the door to the development of powerful...
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Paul Romatschke10/09/2024, 14:00
In the Standard Model of Physics, the Higgs field is in a
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broken phase at low temperature, and in a symmetric phase at high
temperature, with a second order transition in between. In this talk,
I consider a systematic expansion in N>>1 scalar field components to
access the non-perturbative properties of the PT-symmetric field
theory at low and high temperature. The results are... -
Anders Thomsen10/09/2024, 15:15
RG functions are used in QFT to evolve theories between energy scales and are frequently used in both phenomenology and theory. As we push to ever higher loop-order beta functions in generic gauge-Yukawa-quartic theories, we have observed and utilized an underlying structure to obtain results at 4-3-2 loop order: the beta functions satisfy what is known as the Weyl Consistency Conditions....
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Daniele Dorigoni10/09/2024, 15:45
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Takano Taira10/09/2024, 16:30
The spontaneous symmetry breaking of a continuous symmetry in complex field theory at the exceptional point of the parameter space is known to exhibit interesting phenomena, such as the breakdown of a Higgs mechanism. In this work, we derive the complex Ginzburg-Landau model from a non-Hermitian two-band BCS model via path integral and investigate its spontaneous symmetry breaking. We find...
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Michael Ogilvie11/09/2024, 09:30
The physics of QCD at nonzero density and temperature is rich, accessible via theory and experiment, and important for several areas of physics. The path integral is complex at nonzero density, and difficult to evaluate: there is a sign problem which reflects an underlying PT symmetry. We show that novel new phases associated with PT symmetry breaking, including liquid-like phases and...
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Massimo Blasone11/09/2024, 10:15
I will review recent work on the quantization for mixed fields, with particular reference to the case of neutrinos. I will argue on the physical relevance of flavor states, which are associated to a condensate structure of the flavor vacuum, induced by a Bogoliubov transformation. Phenomenological consequences of this result will be discussed.
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Based on the analogy of oscillating neutrinos... -
Andreas Stergiou11/09/2024, 11:15
General properties of the renormalisation group (RG) are of immense theoretical interest, as they have implications for the evolution of physical systems from high to low energies. In a perturbative setting, RG flows are determined by a vector field, the beta function, that can be computed in a loop expansion. In this talk, we will discuss the gradient property of the RG up to six loops in...
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Francisco Correa11/09/2024, 12:00
This talk will review recent developments linking integrable models, soliton theory, and field theories. Through several examples, it will illustrate how the influence of non-Hermitian physics and PT symmetry leads to new theories, integrable models, and soliton solutions. These advances have interesting applications across various fields, including classical field theories, many-particle...
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Peter Millington11/09/2024, 13:45
Physical frameworks are often at their most interesting when we stress-test their underlying assumptions. This is no less true of quantum field theory, and no less true of relaxing the constraint of Hermiticity of the Hamiltonian. I will review progress in pseudo-Hermitian quantum field theory and argue that non-Hermiticity represents an exciting paradigm in which to attack long-standing...
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Nick Mavromatos11/09/2024, 14:30
In the context of string-inspired Chern Simons (CS) gravity, involving axion-like fields interacting with gravitational CS anomalous terms, I discuss the formation of condensates of the latter due to quantum graviton modes of chiral gravitational wave type, that could exist in the primordial universe. The condensates are complex, with their imaginary parts being associated with instabilities...
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Joan Sola Peracaula11/09/2024, 15:45
In the last few years the idea that the vacuum energy density (VED) is a `running' quantity with the cosmological evolution has become phenomenologically advantageous, as it helps in alleviating the current cosmological tensions afflicting the ΛCDM. The theoretical studies backing up this approach go under the name of "running vacuum model" (RVM). Using this framework, based on quantum field...
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Sarben Sarkar11/09/2024, 16:30
We consider a string inspired effective axion anomalously coupled to Abelian gauge fields and gravity via Chern-Simons couplings. By considering the renormalisation group flows in the flat space limit it is observed that a Hermitian parity symmetric phase of the theory can flow into a non-Hermitian parity-time symmetric phase.
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This behavior has implications for Chern-Simons gravity. The... -
Ian Moss12/09/2024, 09:30
In nature, most examples of bubbe nucleation occur around nucleation seeds. Clouds are an example, were particles of dust are needed to start off the process of making rain. The theory of nucleation around seeds in phase transitions or in false vacuum decay is a rich one, with interesting outcomes. The theory has applications to laboratory vacuum decay experiments, stimulated decay from...
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Oliver Gould12/09/2024, 10:15
First-order phase transitions proceed via bubble nucleation. This is true regardless of whether the transition is happening in your kettle or on a cosmological scale in the very early universe. The rate of bubble nucleation determines many gross features of cosmological phase transitions, including the peak frequency of the resulting gravitational wave signal. At high temperatures, the rate...
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Ruth Gregory12/09/2024, 11:15
Horizons can occur in a wide range of physical situations, many of which we can construct in the lab, leading to the field of Analog Gravity. Most gravity simulators observe features, like super-radiance, that are analysed as a continuum effect in gravity, whereas many interesting "beyond GR" features theorise about the impact of quantised aspects of the black hole. In this talk, I will...
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Manuel Reichert12/09/2024, 13:15
A consistent theory of quantum gravity needs to be able to incorporate the matter degrees of freedom present in our Universe, for example, the matter fields and symmetries of the Standard Model. In asymptotically safe quantum gravity, the key questions are for which matter content the interacting ultraviolet fixed point exists, and which low-energy matter interactions are connected to the...
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Björn Garbrecht12/09/2024, 14:00
There is no empirical evidence for CP conservation in the strong
interactions. As there generally is a renormalizable, parity-odd
coupling between the field strength and its dual, this requires an
explanation from theory.I will therefore first review what interactions are present when
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constructing an effective theory for hadrons from QCD. But I will also
point out, that from such... -
Matthias Carosi12/09/2024, 14:45
Computing the false vacuum decay rate for the classically scale invariant scalar theory is particularly relevant for assessing the stability of the Standard Model. This proves particularly challenging as the classical scale invariance introduces an additional non-normisable zero-mode that cannot be treated through standard methods. We show how the Green's function method can be employed to...
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Rocky Kolb12/09/2024, 15:45
Some seemingly well-behaved quantum field theories in Minkowski space may develop pathological behaviors in certain gravitational backgrounds. This seems to be especially true of QFTs of higher spin. For example, the early universe may be used as a probe such theories. Perhaps there is a swampland of Minkowskian QFTs that cannot be lifted to certain cosmological backgrounds.
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Azadeh Maleknejad12/09/2024, 16:30
Gauge fields and fermions are the building blocks of particle physics models. I will summarize some progress in understanding their production and contribution to the physics of cosmic inflation. In particular, I will focus on the case of non-Abelian gauge fields in axion inflation and discuss their rich phenomenology as well as their observable signatures on CMB and GW background. In these...
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Tim R. Morris13/09/2024, 09:30
If the metric is chosen to depend exponentially on the conformal factor, and if one works in a gauge where the conformal factor has the wrong sign propagator, perturbative quantum gravity corrections can be partially resummed into a series of terms each of which is ultraviolet finite. These new terms however are not perturbative in some small parameter, and are not individually BRST invariant,...
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Alex Soto13/09/2024, 10:15
We present from first principles, under the Schwinger-Keldysh path integral formalism, equations for bosonic, non-relativistic and self-interacting dark matter which can include both a condensed, low momentum “fuzzy” component and one with higher momenta that may be approximated as a collection of particles. The equations can describe both CDM and Fuzzy Dark Matter in a unified way. We show...
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Graham White13/09/2024, 11:15
Domain walls are a defect that arises when a vacuum manifold is discontinuous. They are often regarded as a problem - literally the "domain wall problem" - but if you can get rid of them, they could be an interesting source of gravitational waves. If the domain walls result from a breaking a global symmetry, the most common way of doing so always struck me as contrived - having an unnaturally...
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Jean Alexandre13/09/2024, 12:00
Finite-volume effects in QFT allow the violation of the Null Energy Condition, without modified gravity or exotic matter. After reviewing few known features arising from the Casimir effect, I will explain that tunnelling between degenerate vacua also induces NEC violation. I will then discuss resulting mechanisms which can help avoid singularities in gravity.
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Tom Rudelius13/09/2024, 14:00
Axions provide one of the most promising routes for bridging the gap between string theory and experiment. In this talk, we will focus on several observed features of the string landscape (e.g. the absence of global symmetries and the Weak Gravity Conjecture) and their implications for axion physics (e.g. the axion quality problem and axion inflation). I will also introduce the notion of an...
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31. New Hermitian and Non-Hermitian Toda field theories and Calogero models from infinite symmetriesAndreas Fring13/09/2024, 15:15
Many integrable theories can be formulated universally in terms of Lie algebraic root systems. Examples are conformal field theories that can be expressed in terms of the simple roots of finite Lie algebras, massive field theories that can be written in terms of simple roots of the affine Kac-Moody algebras and Calogero (Moser-Sutherland) models that require the entire root system of the...
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Marc Winstel13/09/2024, 16:00
In this talk, I present the phase diagram of a (2+1)-dimensional four-fermion model at finite temperature and chemical potential, which is invariant under a chiral symmetry transformation as well as a generalized PT-symmetry transformation. Besides the ordinary phase with chiral symmetry breaking, a regime is observed where mesonic two-point correlation functions feature spatial oscillations,...
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Charlie Cresswell-Hogg13/09/2024, 16:30
Theories of self-interacting fermions play an important role in particle and condensed matter physics, covering effective descriptions of the strong nuclear force, the critical behaviour of Dirac materials such as graphene, and more. In this talk, I will discuss functional RG flows for fermionic systems in the large-N limit. I provide conditions under which these flows become exact, and...
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Dr Takano Taira (University of Tokyo, Institute of industrial science)
The spontaneous symmetry breaking of a continuous symmetry in complex field theory at the exceptional point of the parameter space is known to exhibit interesting phenomena, such as the breakdown of a Higgs mechanism. In this work, we derive the complex Ginzburg-Landau model from a non-Hermitian two-band BCS model via path integral and investigate its spontaneous symmetry breaking. We find...
Go to contribution page -
Matthias Carosi
Computing the false vacuum decay rate for the classically scale invariant scalar theory is particularly relevant for assessing the stability of the Standard Model.
Go to contribution page
This proves particularly challenging as the classical scale invariance introduces an additional non normalisable zero-mode that cannot be treated through standard methods.
We show how the Green's function method can be employed to...
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