In this study, the methodology proposed by Goon and Penco for investigating the universality of thermodynamic relations with corrections in de Sitter black holes is extended. A universal thermodynamic extremality relation, considering the spacetime mass $\textit{M}$ with various state parameters, proposed by Goon and Penco is investigated in higher-dimensional spacetime. The established universal conclusions are not impacted by the convergence of energy from the coexistence region of two horizons to the point $\textit{N}$ or $\textit{C}$. Furthermore, by incorporating the shift of the angular momentum into our analysis, a more universal relation is derived, specifically applicable to rotating configurations. Notably, a novel conjecture is formulated that establishes a universal relationship framework connecting shifted thermodynamic quantities across arbitrary black hole backgrounds. These findings are expected to offer profound insights into the fundamental principles of quantum gravity.

China

Hai-Long Zhen

Yu-Bo Ma

Universality on the thermodynamic relation with corrections in higher-dimensional de Sitter black holes

We start with the consideration of the loop effects for light fields with nonzero mass in the expanding Poincaré patch of de Sitter spacetime. We derive the Dyson-Schwinger equation, which sums up the leading infrared (growing with time) loop corrections in certain limit for small initial perturbations above the Bunch-Davies state. The solution of this equation shows the destiny of the initial state at the future infinity. Then we discuss the case of the contracting Poincaré patch and global de Sitter spacetime and briefly the case of different initial conditions in the expanding Poincaré patch.

Russia

E.T. Akhmedov

V.I. Lapushkin

D.I. Sadekov

Light fields in various patches of de Sitter spacetime

We show how certain types of magnetic asymptotically anti–de Sitter Euclidean wormholes can catalyze the onset of inflation. These wormholes can be embedded as saddle point solutions of general relativity coupled to the Standard Model, the inflaton being identified with the Higgs particle. Our scenario is based on the assumption that the quantum effective potential for the Higgs turns negative at a certain high energy window, in line with current measured values for the Higgs and top quark masses. Within our proposal, we can estimate various parameters and physical quantities of interest, in consistency with current observational bounds.

Belgium

Panos Betzios

Estonia

Ioannis D. Gialamas

France

Olga Papadoulaki

Magnetic anti–de Sitter wormholes as seeds for Higgs inflation

The bulk reconstruction program involves expressing local bulk fields as non-local operators on the boundary. It was initiated in the context of AdS/CFT correspondence. Attempts to extend it to de Sitter have been successful for heavy (principal series) scalar fields. For other fields, the construction ran into issues. In particular, divergences were found to appear for higher spin fields. In this paper, we resolve these issues and obtain boundary representations for scalars of all masses as well as higher spin fields. We trace the origin of the previously discovered divergences and show that the smearing function becomes distributional for certain values of mass, spin and dimension. We also extend the construction from Bunch-Davies vacuum to all <italic>&#945;</italic>-vacua.

India

Arundhati Goldar

Nirmalya Kajuri

Bulk reconstruction in de Sitter spacetime

We investigate Λ production in the ( <math altimg='si146.svg'><msup><mrow><mi>&#960;</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup></math>, <math altimg='si3.svg'><msup><mrow><mi>K</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup></math>) reaction on a 6Li target at <math altimg='si4.svg'><msub><mrow><mi>p</mi></mrow><mrow><msup><mrow><mi>&#960;</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup></mrow></msub><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><mn>1.05</mn></math> GeV/ <italic>c</italic>, using the distorted-wave impulse approximation (DWIA) with the Fermi-averaged <math altimg='si5.svg'><msup><mrow><mi>&#960;</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup><mi>n</mi><mo stretchy='false'>&#8594;</mo><msup><mrow><mi>K</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup><mi mathvariant='normal'>&#923;</mi></math> amplitudes. The calculated spectrum is in good agreement with the experimental data, suggesting that <math altimg='si1.svg'><mmultiscripts><mrow><mi mathvariant='normal'>He</mi></mrow><mprescripts /><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>4</mn></mrow></mmultiscripts></math>- <italic>d</italic> configurations play a key role in describing the &#923; continuum states of <math altimg='si23.svg'><msubsup><mrow /><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>6</mn></mrow></msubsup></math>Li near and above the <math altimg='si8.svg'><mmultiscripts><mrow><mi mathvariant='normal'>He</mi></mrow><mprescripts /><none /><mrow><mn>3</mn></mrow></mmultiscripts><mo linebreak='goodbreak' linebreakstyle='after'>+</mo><mi>d</mi><mo linebreak='goodbreak' linebreakstyle='after'>+</mo><mi mathvariant='normal'>&#923;</mi></math> threshold. Our analysis shows that the <math altimg='si1.svg'><mmultiscripts><mrow><mi mathvariant='normal'>He</mi></mrow><mprescripts /><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>4</mn></mrow></mmultiscripts></math> hypernucleus as a hyperfragment is prominently produced through <italic>D</italic>-wave resonances with <math altimg='si9.svg'><msup><mrow><mi>J</mi></mrow><mrow><mi>P</mi></mrow></msup><mo linebreak='goodbreak' linebreakstyle='after'>=</mo><msup><mrow><mn>3</mn></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup></math>, <math altimg='si10.svg'><msup><mrow><mn>2</mn></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup></math>, and <math altimg='si11.svg'><msup><mrow><mn>1</mn></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup></math> in the <math altimg='si108.svg'><mmultiscripts><mrow><mi mathvariant='normal'>He</mi></mrow><mprescripts /><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>4</mn></mrow></mmultiscripts><mo linebreak='goodbreak' linebreakstyle='after'>+</mo><mi>d</mi></math> channel at a large momentum transfer <math altimg='si13.svg'><mi>q</mi><mo>&#8771;</mo><mn>360</mn></math>&#8211;400 MeV/ <italic>c</italic>. These findings provide theoretical evidence for the production of a <math altimg='si1.svg'><mmultiscripts><mrow><mi mathvariant='normal'>He</mi></mrow><mprescripts /><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>4</mn></mrow></mmultiscripts></math> hyperfragment via a cluster-like mechanism in the 6Li( <math altimg='si146.svg'><msup><mrow><mi>&#960;</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup></math>, <math altimg='si3.svg'><msup><mrow><mi>K</mi></mrow><mrow><mo linebreak='badbreak' linebreakstyle='after'>+</mo></mrow></msup></math>) reaction.

Japan

Toru Harada

Yoshiharu Hirabayashi

Evidence for <math altimg='si1.svg'><mmultiscripts><mrow><mi mathvariant='normal'>He</mi></mrow><mprescripts /><mrow><mi mathvariant='normal'>&#923;</mi></mrow><mrow><mn>4</mn></mrow></mmultiscripts></math> hyperfragment production in the 6Li( <italic>&#960;</italic> +, <italic>K</italic> +) reaction

Compared with the Poincaré braneworld, the de Sitter (dS) braneworld aligns more closely with the present universe characterized by a small but finite cosmological constant. To explore the quasinormal ringing properties within the dS brane scenario, we investigate the gravitational perturbations in both thin and thick dS brane configurations. Analysis of the perturbation equations reveals that the effective potential along the extra dimension exhibits the shape of Pöschl-Teller potential, asymptotically approaching a constant value (mass gap) at infinity. In particular, this mass gap can be reduced. And analytical calculations further indicate that the gravitational perturbations, apart from the zero mode, possess a series of discrete, purely imaginary quasinormal modes in the late stages. This result implies that these perturbations decay without oscillation over time. The analytical findings also demonstrate that the brane structure primarily determines the distribution of the quasinormal spectrum while preserving the purely imaginary nature of the quasinormal frequencies. Subsequently, we further simulate the gravitational wave signal by numerically evolving the perturbation equations, which yield late-stage results consistent with the analytical predictions. Interestingly, these quasinormal modes carry information about the cosmological constant on the brane, which provides a potential new pathway for the study of cosmology in the dS brane scenario.

Hai-Long Jia

Wen-Di Guo

Yu-Xiao Liu

Qin Tan

Quasinormal ringing of de Sitter braneworlds

We advance the study of pure de Sitter supergravity by introducing a finite formulation of unimodular supergravity via the super-Stückelberg mechanism. Building on previous works, we construct a complete four-dimensional action of spontaneously broken <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="script">N</mi><mo>=</mo><mn>1</mn></math> supergravity to all orders in the Stückelberg fields, which allows for de Sitter solutions. The introduction of finite supergravity transformations extends the super-Stückelberg procedure beyond the second order, offering a recursive solution to all orders in the Goldstino sector. This work bridges the earlier perturbative approaches and the complete finite theory, opening new possibilities for de Sitter vacua in supergravity models and eventually string theory.

Austria

Sukṛti Bansal

United Kingdom

Silvia Nagy

Antonio Padilla

Ivonne Zavala

Stückelberg path to pure de Sitter supergravity

The 1 + 3-de Sitter space, as a solution of Einstein’s equations, provides a framework for investigating various physical concepts, including quantum mechanics. In this context, the group Sp(2,2) plays a crucial role as the universal covering of the de Sitter space, contributing significantly to the understanding of associated quantum mechanics. In this study, the presentation of infinitesimal generators of the group Sp(2,2) and quantum operators on the de Sitter space is conducted using the coherent states quantization method, also known as Berezin’s quantization method. This approach allows for a systematic examination of the generators and operators within the quantum framework. Furthermore, the exploration of these generators and operators is facilitated by the unitary representation of the principal series of the group Sp(2,2), offering insights into the underlying quantum mechanics principles governing the de Sitter space.

Iran

A. Rabeie

Infinitesimal generators and quantum operators in de Sitter space

Jackiw-Teitelboim (JT) gravity in two-dimensional de Sitter space is an intriguing model for cosmological “wave functions of the universe”. Its minisuperspace version already contains all physical information. The size of compact slices is parametrized by a scale factor $\textit{h}$ > 0. The dilaton $\textit{ϕ}$ is chosen to have positive values and interpreted as size of an additional compact slice in a higher-dimensional theory. At the boundaries $\textit{h}$ = 0, $\textit{ϕ}$ = 0, where the volume of the universe vanishes, the curvature is generically singular. According to a conjecture by DeWitt, solutions of the Wheeler-DeWitt (WDW) equation should vanish at singular loci. Recently, the behaviour of JT wave functions at large field values $\textit{h}$, $\textit{ϕ}$ has been obtained by means of a path integral over Schwarzian degrees of freedom of a boundary curve. We systematically analyze solutions of the WDW equation with Schwarzian asymptotic behaviour. We find real analytic solutions that vanish on the entire boundary, in agreement with DeWitt’s conjecture. Projection to expanding and contracting branches may lead to singularities, which can however be avoided by an appropriate superposition of solutions. Our analysis also illustrates the limitations of semiclassical wave functions.

Germany

Wilfried Buchmüller

Arthur Hebecker

Alexander Westphal

DeWitt wave functions for de Sitter JT gravity

We revisit duality-covariant higher-derivative corrections which arise from the generalized Bergshoeff-de Roo (gBdR) identification, a prescription that gives rise to a two parameter family of $\textit{α}$ -corrections to the low-energy effective action of the bosonic and the heterotic string. Although it is able to reproduce all corrections at the leading and sub-leading ($\textit{α}$ ) order purely from symmetry considerations, a geometric interpretation, like for the two-derivative action and its gauge transformation is lacking. To address this issue and to pave the way for the future exploration of higher-derivative (=higher-loop for the $\textit{β}$-functions of the underlying $\textit{σ}$-model) corrections to generalized dualities, consistent truncations and integrable $\textit{σ}$-models, we recover the gBdR identification’s results from the Poláček-Siegel construction that provides a natural notion of torsion and curvature in generalized geometry.

Poland

Achilleas Gitsis

Falk Hassler

Unraveling the generalized Bergshoeff-de Roo identification