Using functional integral methods, we investigate the non-Abelian Casimir energy in the Curci-Ferrari model, which offers an effective description of the infrared regime of Yang-Mills theory. We consider a 3+1D (resp. 2+1D) system of two infinite parallel plates (resp. wires) at a fixed distance from each other, with either perfect magnetic conductor (PMC) or perfect electric conductor (PEC) boundary conditions. Imposing the boundary conditions directly in the functional integral by the introduction of suitable auxiliary fields that act as Lagrange multipliers, we obtain a boundary effective action that captures the dynamics of this system. The Casimir energy is then computed both directly from the functional integral and via the energy-momentum tensor, providing equivalent results. We find that the Casimir energy for PEC and PMC conditions differs by a constant factor, which can be traced back to a van Dam-Veltman-Zakharov-like discontinuity (both in 3+1D and 2+1D). Lastly, we show that our analytical results are compatible with a variety of recent numerical lattice simulations of the non-perturbative Yang-Mills Casimir energy, in which a novel non-perturbative mass scale emerges.

Belgium

David Dudal

Brazil

Philipe Fabritiis

Sebbe Stouten

Non-Abelian Casimir energy in the Curci-Ferrari model through a functional approach

We explore asymptotically locally anti-de Sitter spacetimes exhibiting gravitational radiative behavior, employing null gauges that allow for a well-defined flat limit. The radiative content in the bulk is captured by the boundary Cotton and stress tensor, which we collect into a radiative vector. We reinterpret this vector holographically in terms of fluid variables in the dual boundary theory. For algebraically special solutions, we uncover a close connection between bulk radiation and dissipative corrections in the boundary stress tensor, demonstrating a direct link between radiation and entropy production in the boundary fluid. This reveals a rich interplay between radiative dynamics in the bulk and out-of-equilibrium conformal physics at the boundary. We then investigate the flat limit of this correspondence in the context of flat-space holography. In this setting, we construct a Carrollian analogue of the radiative vector and introduce Celestial observables, such as energy detectors, which emerge naturally from the bulk’s radiative structure. Our analysis shows that bulk radiation sources the Carrollian viscous stress tensor and heat current, which encodes the Bondi news in this framework. We illustrate our results with explicit examples, including Robinson-Trautman spacetimes and accelerating black holes.

China

Gabriel Arenas-Henriquez

Canada

Luca Ciambelli

Russia

Felipe Diaz

Weizhen Jia

David Rivera-Betancour

Radiation in fluid/gravity and the flat limit

In this paper, we extend our previous results on the gravitational interactions for massive spin 5/2 particles and spin 3 particles to massive spin 7/2, including its massless and partially massless limits. These results share some common features, such as a non-singular massless limit in AdS and a flat limit for non-zero masses, as well as a singularity at the points corresponding to the boundary of the unitary forbidden region. At the same time, these results allow us to suggest what the structure of non-minimal interactions for arbitrary spins looks like. Another subject of interest is the Skvortsov-Vasiliev formalism for describing free partially massless fields. This formalism has been very useful in our research, but our examples have shown that the application of the Fradkin-Vasiliev formalism for constructing interactions based on such description does not always lead to the correct results.

Yu. Zinoviev

On massive higher spins and gravity. Part III. Spin 7/2

The four-dimensional Chern-Simons (CS) theory provides a systematic procedure for realizing two-dimensional integrable field theories. It is therefore a natural question to ask whether integrable deformations of the theories can be realized in the four-dimensional CS theory. In this work, we study $$T\overline{T}$$ and root- $$T\overline{T}$$ deformations of two-dimensional integrable field theories, formulated in terms of dynamical coordinate transformations, within the framework of four-dimensional CS theory coupled to disorder defects. We illustrate our procedure in detail for the degenerate $$\mathcal{E}$$ -model, a specific construction that captures and unifies a broad range of integrable systems, including the principal chiral model.

Japan

Jun-ichi Sakamoto

Italy

Roberto Tateo

Masahito Yamazaki

$$T\overline{T}$$ and root- $$T\overline{T}$$ deformations in four-dimensional Chern-Simons theory

Cosmological collider physics allows the detection of heavy particles at inflationary scales through their imprints on primordial non-Gaussianities. We study the chemical potential mechanism applied to a pair of charged scalars. We analytically evaluate the resulting one-loop contribution to the bispectrum, using the spectral decomposition. In this way we are able to determine the parametric dependencies for both the signal and the background. We show that a signal strength $${f}_{\text{NL}}\sim \mathcal{O}(0.01)$$ can be obtained within theoretical control, potentially reachable by 21 cm tomography. As an application we consider the colored Higgs bosons in SU(5) supersymmetric orbifold grand unification with masses $\textit{M}$ ≲ 10 GeV.

United States

Arushi Bodas

Edward Broadberry

Raman Sundrum

Zhaohui Xu

Charged loops at the cosmological collider with chemical potential

We consider a simple Higgs portal dark matter (DM) model, where the Standard Model is extended with a complex singlet scalar. The imaginary part of the scalar becomes a massive and stable pseudo-Nambu-Goldstone boson, serving as the DM candidate, while the real part gives rise to a second (dark) Higgs boson. We focus on the freeze-in production of the DM, paying particular attention to low-reheating temperature scenarios, where the dark Higgs can be a long-lived particle (LLP). We also explore the phenomenology of this dark Higgs at the LHC and the Future Circular Collider in hadron-hadron mode, discussing its discovery prospects in regions of parameter space consistent with current DM constraints. Our results emphasize the impact of the cosmic reheating dynamics on the DM freeze-in production, and their critical role in interpreting collider signatures. Furthermore, our findings suggest that LLP searches may provide insights into the fundamental dynamics of reheating.

United Arab Emirates

Nicolás Bernal

Chile

Giovanna Cottin

Bastián Díaz Sáez

Manuel López

Testing frozen-in pNGB dark matter with a long-lived dark Higgs

We propose a unified framework that describes both the curvaton mechanism for generating primordial density fluctuations and the Affleck-Dine (AD) mechanism for baryogenesis. By introducing a complex scalar field (AD field) carrying a baryon/lepton number and its potential consisting of quadratic and quartic terms with a small baryon/lepton-number-violating mass term, we investigate the evolution of the scalar field during the radiation-dominated era following inflation. We set the initial conditions such that the quartic term dominates the scalar potential, and the angular component of the AD field is non-zero. We focus on a scenario where the AD field sufficiently dominates the energy density of the universe before its decay. We show that the radial component of the AD field can be identified with the curvaton to solely produce the Planck normalized scalar power spectrum while the evolution of the angular component is crucial for generating the observed baryon asymmetry of the universe. Additionally, we find that the amplitude of scalar bispectrum $\textit{f}$ is negative, which is consistent with the current Planck data and testable in future observations such as CMB-S4, LiteBIRD, LSS, and 21-cm experiments. In our estimation of the scalar power spectrum and bispectrum, we develop a novel analytical scheme for computing scalar fluctuations based on the $\textit{δN}$ formalism, which allows us to deal with the evolution of curvaton with polynomial potential more accurately in comparison to the existing analytical methods.

Poland

Anish Ghoshal

Abhishek Naskar

Nobuchika Okada

Unified origin of curvature perturbation and baryon asymmetry of the universe

We investigate the impact of dark Abelian gauge bosons on the electroweak precision measurements at the one-loop level. The dark gauge boson couples to the standard model fermions generally via two kinds of mixing with the electroweak gauge bosons: the kinetic mixing and the mass mixing. We solve the Schwinger-Dyson equation for the gauge boson propagators and derive a renormalization scheme-independent representation of the scattering amplitudes for four-fermion processes, including the full oblique corrections. We define the running parameters at the one-loop level and show that the leading new physics effects, including the mixing, in the electroweak precision observables can be described by the oblique parameters $\textit{S}$, $\textit{T}$, and $\textit{U}$ as in the standard electroweak gauge theory when the new physics scale is sufficiently high and the dark gauge boson mass lies away from the $\textit{Z}$ pole. We consider the dark doublet scalar boson as an example and numerically show that a novel one-loop effect can drastically change the parameter region allowed by the electroweak precision tests.

Taiwan

Cheng-Wei Chiang

Kazuki Enomoto

Oblique corrections in general dark U(1) models

Semi-holography provides a formulation of dynamics in gauge theories involving both weakly self-interacting (perturbative) and strongly self-interacting (non-perturbative) degrees of freedom. These two subsectors interact via their effective metrics and sources, while the full local energy-momentum tensor is conserved in the physical background metric. In the large $\textit{N}$ limit, the subsectors have their individual entropy currents, and so the full system can reach a pseudo-equilibrium state in which each subsector has a different physical temperature.

Germany

Toshali Mitra

India

Sukrut Mondkar

Ayan Mukhopadhyay

Slovenia

Alexander Soloviev

Hybrid thermalization in the large $\textit{N}$ limit

One of the key issues in holography is going beyond AdS and defining quantum gravity in spacetimes with a null boundary. Recent examples of this type involve linear dilaton asymptotics and are related to the $$T\overline{T }$$ deformation. We present a holographic correspondence derived from string theory, which is an example of a kind of celestial holography. The holographic definition is a spacetime non-commutative open string theory supported on D1-D5 branes together with fundamental strings. The gravity solutions interpolate between AdS metrics and six-dimensional metrics. Radiation can escape to null infinity, which makes both the encoding of quantum information in the boundary and the dynamics of black holes quite different from AdS spacetimes.

Christian Ferko

Savdeep Sethi

Holography with null boundaries