We employ the Fuzzy Sphere regulator to study the 3D Lee-Yang CFT. The model is defined by deforming the Ising model on the Fuzzy Sphere via a purely imaginary longitudinal magnetic field. This model undergoes a quantum phase transition, whose critical point we determine and identify with the 3D Lee-Yang CFT. We show how to tune the model and find that the lowest-lying states of the Hamiltonian align well with the expected CFT spectrum. We discuss the Fuzzy Sphere estimates for the scaling dimension ∆ of the lowest primary operator. Finally, we interpret small deviations from the CFT expectations in terms of the leading irrelevant operators of the Lee-Yang CFT. We show that the Fuzzy Sphere calculations are compatible with the best five-loop $\textit{ϵ}$-expansion estimates.

Italy

Joan Miró

Switzerland

Olivier Delouche

Flowing from the Ising model on the fuzzy sphere to the 3D Lee-Yang CFT

The study of effective potential for the scalar Lee-Wick pseudo-electrodynamics in one-loop is presented in this letter. The planar and non-local Lee-Wick pseudo-electrodynamics is so coupled to a complex scalar field sector in <math altimg='si2.svg'><mrow><mn>1</mn><mo linebreak='goodbreak'>+</mo><mn>2</mn></mrow></math> dimensions, where we achieve the Lee-Wick pseudo-scalar electrodynamics. The effective action formalism is applied such that the quantum corrections are examined in one loop to the scalar effective potential as function of the classical field, of the Lee-Wick mass, and also of the coupling constants of this model. The instability of the effective potential is investigated due to Lee-Wick mass.

Brazil

M.J. Neves

Effective potential of scalar Lee-Wick pseudo-electrodynamics

We study compact kinks in a modified Christ-Lee model where the potential is a non-analytic function at the minima. The model has two control parameters that determine the order of the potential and its overall shape. We consider cases in which the potential has a double well shape, a triple well shape, as well as cases with a false vacuum. Compact kink solutions and their internal modes are found for each of these cases. We also study the collision of such kinks and their dependence on the solitons velocity and on the potential parameters. Several interesting dynamical processes are reported, such as the formation of central oscillons for some high velocity collisions, absence of outgoing solitons in cases where the potential is given by piece-wise linear functions, and the decoupling of subkinks from the larger kink in cases with false vacuum, leading to the formation of false vacuum bubbles.

F. Hahne

R. Thibes

Compact kinks in a modified Christ-Lee model

In this study, we present several improvements of the non-relativistic Friedrichs-Lee model with multiple discrete and continuous states while retaining its solvability. Our findings establish a solid theoretical basis for the exploration of resonance phenomena in scenarios involving multiple interfering states across various channels. The scattering amplitudes associated with the continuum states naturally adhere to coupled-channel unitarity, rendering this framework particularly valuable for investigating hadronic resonant states appearing in multiple coupled channels. Moreover, this generalized framework exhibits a wide-range applicability, enabling investigations into resonance phenomena across diverse physical domains, including hadron physics, nuclear physics, optics, cold atom physics, etc.

China

Zhiguang Xiao

Zhi-Yong Zhou

On the generalized Friedrichs-Lee model with multiple discrete and continuous states * Supported by China National Natural Science Foundation (11975075, 12375132, 12375078, 11575177, 11947301, 12335002), also supported by the Fundamental Research Funds for the Central Universities

Without invoking any cumulant determination at the input level, we present here the first calculations of direct estimates of the Lee-Yang zeros of the QCD partition function in (<math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>2</mn><mo>+</mo><mn>1</mn></mrow></math>)-flavor QCD. These zeros are obtained in the complex isospin chemical potential <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>μ</mi><mi>I</mi></msub></math> plane using the unbiased exponential resummation formalism on <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>N</mi><mi>τ</mi></msub><mo>=</mo><mn>8</mn></math> lattices and with physical quark masses. For different temperatures, we illustrate the stability of the zeros closest to the origin from which we subsequently procure the radius of convergence estimates. From the temperature-dependence study of the real and imaginary parts of these zeros, we try estimating one of the possible critical points forming the second-order pion condensate critical line in the isospin phase diagram. Further, we compare these resummed estimates with the corresponding Mercer-Roberts estimates of the subsequent Taylor series expansions of the first three partition function cumulants. We also outline comparisons between resummed and Taylor series results of these cumulants for real and imaginary values of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>μ</mi><mi>I</mi></msub></math> and highlight the behavior of different expansion orders within and beyond the obtained resummed estimates of the radius of convergence. We also reestablish that this resummed radius of convergence can efficiently capture the onset of the overlap problem for finite real <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>μ</mi><mi>I</mi></msub></math> simulations.

Germany

Sabarnya Mitra

Estimates of Lee-Yang zeros and a possible critical point on the pion condensate boundary in the QCD isospin phase diagram using an unbiased exponential resummation on the lattice

Domain walls are the simplest type of topological defects formed at cosmological phase transitions, and one of the most constrained. Their studies typically assume a quartic double well potential, but this model is not fully representative of the range of known or plausible particle physics models. Here, we study the cosmological evolution of domain walls in two other classes of potentials. The Sine-Gordon potential allows several types of walls, interpolating between different pairs of minima (which demands specific numerical algorithms to separately measure the relevant properties of each type). The Christ-Lee potentials parametrically interpolates between sextic and quartic behavior. We use multiple sets of simulations in two and three spatial dimensions, for various cosmological epochs and under various choices of initial conditions, to discuss the scaling properties of these networks. In the Sine-Gordon case, we identify and quantify deviations from the usual scaling behavior. In the Christ-Lee case, we discuss conditions under which walls form (or not) and quantify how these outcomes depend on parameters such as the energy difference between the false and true vacua and the expansion rate of the Universe. Various biased initial conditions are also addressed in the Appendixes. Finally, we briefly comment on the possible cosmological implications of our results.

Portugal

R. Heilemann

M.C. Rosa

Finland

J.R.C.C.C. Correia

C.J.A.P. Martins

Domain wall evolution beyond quartic potentials: The Sine-Gordon potential and Christ-Lee potentials

It has recently been pointed out that rotation in internal space can induce superradiance. We explore this effect in non-topological solitons of the two-field Friedberg-Lee-Sirlin model. This renormalizable model admits very large solitons, making the perturbative scattering equations highly sensitive to boundary conditions and requiring a relaxation method for their solution. We find that the energy extraction rate is strongly influenced by the mass hierarchy of the two scalars, and solitons with lower internal frequencies lead to more peaks in the spectra of the amplification factors. Additionally, we derive absolute bounds on the amplification factors for general ingoing modes using a linear fractional optimization algorithm and establish analytical bounds near the mass gap.

Guo-Dong Zhang

Cheng-Hao Li

United Kingdom

Qi-Xin Xie

Shuang-Yong Zhou

Superradiance of Friedberg-Lee-Sirlin solitons

We propose a method to numerically determine the location of a critical point in general systems using the finite-size scaling of Lee-Yang zeros. This method makes use of the fact that the ratios of Lee-Yang zeros on various spatial volumes intersect at the critical point. While the method is similar to the Binder-cumulant analysis, it is advantageous in suppressing the finite-volume effects arising from the mixing of variables in general systems. We show that the method works successfully for numerically locating the critical point in the three-dimensional three-state Potts model with a nonzero external field.

Japan

Tatsuya Wada

Masakiyo Kitazawa

Kazuyuki Kanaya

Locating Critical Points Using Ratios of Lee-Yang Zeros

We study some phenomenological aspects of Lee-Wick (LW) QED. In particular, we show that LW QED implies charge dequantization and a flavor-dependent LW scale. We study the implications of the Weak Gravity Conjecture (WGC) in LW QED and calculate the modified electric force and potential and use the former to reformulate the WGC in LW QED. We also calculate the photon self-energy and the Uehling potential in LW QED. We show that bounds on milli-charged particles from matter neutrality experiments set stringent limits on the LW scale of fermions and of the photon.

India

Fayez Abu-Ajamieh

Pratik Chattopadhyay

Marco Frasca

Phenomenological aspects of Lee-Wick QED

In this paper, the dimensional reduction is applied to the Lee-Wick electrodynamics in which the classical sources are confined on a spatial plane. As result, the Lee-Wick pseudoelectrodynamics is achieved as a nonlocal electromagnetism defined in <math><mn>1</mn><mo>+</mo><mn>2</mn></math> dimensions. The Abelian Anderson-Higgs mechanism is so introduced in the Lee-Wick pseudo-electrodynamics through a complex scalar sector in <math><mn>1</mn><mo>+</mo><mn>2</mn></math> dimensions, breaking spontaneously the <math><mi>U</mi><mo>(</mo><mn>1</mn><mo>)</mo></math>-gauge symmetry of the nonlocal theory. As consequence, the pseudo-Lee-Wick field acquires a light mass, beyond the usual heavy Lee-Wick mass, that is a natural mass parameter of the theory. After the spontaneous symmetry breaking takes place, classical features of the theory are discussed, as the pseudo-Proca-Lee-Wick electrodynamics, with the field equations and conservation laws. The introduction of Lee-Wick fermions also is proposed, in which it opens the discussion of a viable pseudo-Proca-Lee-Wick quantum electrodynamics in <math><mn>1</mn><mo>+</mo><mn>2</mn></math> dimensions. The unitarity at the tree level of the Lee-Wick pseudo-electrodynamics is discussed through the optical theorem.

M. J. Neves

Classical features, Anderson-Higgs mechanism, and unitarity in Lee-Wick pseudo-electrodynamics