Here we investigate a general class of massless local theories of spin 2 and spin 3, both invariant under generalized transverse diffeomorphisms (TDiff). We identify the ghost-free region in their parameter space and show the relationship of those models with the “doublet” action stemming from the tensionless limit of the open bosonic string field theory (for symmetric tensors). The connection is implemented via a nonlocal field redefinition which introduces a Stueckelberg-like field of rank 0 (rank 1) for the spin-2 (spin-3) case. An apparent mismatch between most TDiff models and the “doublet” action has led us to prove a nontrivial equivalence among TDiff models, thereby restoring consistency. Any point in the parameter subspace of ghost-free TDiff models is equivalent to any other one within that subspace. In particular, they are all physically equivalent to their simplest versions known as Maxwell-like models. So, the physical TDiff models seem to differ from each other by a Becchi-Rouet-Stora-Tyutin cohomologically trivial term.

Brazil

R. Schimidt Bittencourt

D. Dalmazi

B. dos S. Martins

E.L. Mendonça

Equivalence of spin-2 and spin-3 models invariant under transverse diffeomorphisms and the tensionless limit of string theory

The Hubble tension has profoundly shaped modern cosmological research. This study explores its impact on the early-universe physics in the modified emergent dark energy (MEDE) and $$\Lambda $$ CDM model using Planck PR4, BK18, DESI2024/2025, and supernova samples (Pan+, Union3). First, Hubble constant negligibly affects the tensor-to-scalar ratio ( $$r < 0.031$$ at 95%C.L.). Inclusion of DESI2025 achieves a 46% uncertainty reduction in key parameters. For CMB power spectra, DESI systematically amplifies TT/BB spectral discrepancies. Second, electron ionization fractions $$X_e(z)$$ display pronounced deviations from the $$\Lambda $$ CDM model at $$z=9.17$$ , suggesting a connection between Hubble tension and reionization history. This finding resonates with JWST measurements on high-redshift galaxy evolution. Future observations, such as 21-cm surveys, are highly anticipated to resolve these tensions by probing early-universe evolution and dark energy interactions.

China

Ming-Jian Zhang

Maoyou Yang

Junmei Wang

Testing influence of Hubble tension on the early Universe

We introduce the Higgs mechanism for the self-dual spin connection (also known as the Ashtekar connection), using the Plebański formulation of gravity. We develop our formalism within the framework of the chiral action and derive the equations of motion of the theory. One particular test model is explored: since anisotropy is an intrinsic property of the theory, a modified version of the spatially flat Bianchi I model with two different scale factors is considered. We apply our formalism and derive the Friedmann equations which regulate the scale factors and the Higgs field. We also present a Proca-like term for the connection, which when reduced to minisuperspace with a positive $$\Lambda $$ yields a De Sitter universe with an effective cosmological constant that depends on the mass of the gauge fields. We finally investigate the effect of these mass terms on gravitational waves and find that the wave equation remains unchanged relatively to GR; however the Weyl tensor is scaled by a constant which depends on the mass of the connection components.

United Kingdom

Bruno Alexandre

Higgs mechanism for the Ashtekar self-dual connection

The manifest disparity in Hawking radiation temperatures between black hole and cosmological horizons in de Sitter (dS) spacetime reveals a non-equilibrium thermal configuration, inherently violating thermodynamic stability criteria. This asymmetry poses significant challenges to the systematic analysis of dS thermodynamics. In this study, we construct a thermodynamic framework for dS spacetime under the condition that the system’s thermodynamic quantities adhere to the first law of thermodynamics, while enforcing thermal equilibrium between horizons through radiation temperature-equivalent conditions. Our ansatz postulates that spacetime entropy constitutes both horizon entropy contributions with a supplementary correction term. Through variational analysis constrained by equilibrium thermodynamics, we derive and solve thermodynamic constraints to obtain corrected entropy relations that explicitly resolve the two-horizon entropy puzzle for $\textit{n}$-dimensional charged dilaton-dS black holes. Utilizing these corrected entropy relations, we renormalize associated thermodynamic quantities, thereby establishing self-consistent extended thermodynamics. Numerical solutions of the Gibbs criteria reveal parameter-dependent critical points, where heat capacity is diverging signal possible second-order phase transitions. The system manifests phase transition phenomena, structurally homologous to liquid–gas transition in conventional thermodynamic systems. We proved that the system satisfies the conditions for equilibrium stability, allowing equilibrium phase transitions to occur near critical points.

Hui-Hua Zhao

Yun-Zhi Du

Yu-Bo Ma

Entropy correction and phase transition of $\textit{n}$-dimensional charged dilaton dS black holes

The energy dependence of the cross section of the ( <italic>n,p</italic>) and ( <italic>n,d</italic>) reactions on natC has been studied for the first time at the n_TOF facility at CERN, from the particle detection threshold up to 25 MeV. The measurement was performed with two telescopes made of position-sensitive silicon &#916; <italic>E</italic>- <italic>E</italic> detectors, covering the angular range from 20 &#8728; to 140 &#8728;. A detector efficiency has been determined by means of Monte Carlo simulations of the experimental setup. Various assumptions on the angular distributions and branching ratios of the excited levels of the residual 11B, 12B, 13B nuclei were considered. In particular, theoretical calculations based on the TALYS-2.0 code were used and the systematic uncertainties in the analysis results were determined from the variations in these distributions. The n_TOF data on the ( <italic>n,p</italic>) and ( <italic>n,d</italic>) reaction on carbon are characterized by a higher accuracy and wider energy range than currently available in literature. A comparison with current evaluations from different libraries reveals a rather significant disagreement with the n_TOF results, while a remarkable agreement is observed with the prediction of TALYS-2.0 for this light element.

Croatia

P. Žugec

Italy

N. Colonna

Switzerland

D. Rochman

M. Barbagallo

Poland

J. Andrzejewski

J. Perkowski

A. Ventura

D. Bosnar

A. Gawlik-Ramięga

Spain

M. Sabaté-Gilarte

Austria

France

M. Bacak

F. Mingrone

E. Chiaveri

O. Aberle

V. Alcayne

S. Amaducci

L. Audouin

V. Babiano-Suarez

S. Bennett

E. Berthoumieux

J. Billowes

A. Brown

M. Busso

M. Caamaño

L. Caballero-Ontanaya

F. Calviño

M. Calviani

D. Cano-Ott

A. Casanovas

F. Cerutti

G. Cortés

M.A. Cortés-Giraldo

L. Cosentino

S. Cristallo

L.A. Damone

P.J. Davies

Greece

M. Diakaki

M. Dietz

C. Domingo-Pardo

R. Dressler

Germany

Q. Ducasse

E. Dupont

I. Durán

Z. Eleme

B. Fernández-Domínguez

A. Ferrari

P. Finocchiaro

V. Furman

K. Göbel

R. Garg

S. Gilardoni

Portugal

I.F. Gonçalves

E. González-Romero

C. Guerrero

F. Gunsing

Japan

H. Harada

S. Heinitz

Belgium

J. Heyse

D.G. Jenkins

A. Junghans

F. Käppeler

Y. Kadi

A. Kimura

Czechia

I. Knapová

M. Kokkoris

Y. Kopatch

M. Krtička

D. Kurtulgil

I. Ladarescu

C. Lederer-Woods

H. Leeb

J. Lerendegui-Marco

S.J. Lonsdale

D. Macina

A. Manna

T. Martínez

M. Martínez-Cañada

A. Masi

C. Massimi

P. Mastinu

M. Mastromarco

E.A. Maugeri

A. Mazzone

E. Mendoza

A. Mengoni

V. Michalopoulou

P.M. Milazzo

J. Moreno-Soto

A. Musumarra

Romania

A. Negret

R. Nolte

F. Ogállar

A. Oprea

N. Patronis

A. Pavlik

C. Petrone

L. Piersanti

E. Pirovano

I. Porras

J. Praena

Measurement of the natC( <italic>n,p</italic>) and natC( <italic>n,d</italic>) reactions from n_TOF at CERN

In quantum gravity, it has been argued that a proper accounting of the role played by an observer promotes the von Neumann algebra of observables in a given spacetime subregion from Type III to Type II. While this allows for a mathematically precise definition of its entropy, we show that this procedure depends on which observer is employed. We make this precise by considering a setup in which many possible observers are present; by generalising previous approaches, we derive density operators for the subregion relative to different observers (and relative to arbitrary collections of observers and for arbitrary global physical states), and we compute the associated entropies in a semiclassical regime, as well as in some specific examples that go beyond this regime. We find that the entropies seen by distinct observers can drastically differ. Our work makes extensive use of the formalism of quantum reference frames (QRF); indeed, as we point out, the ‘observers’ considered here and in the previous works are nothing but QRFs. In the process, we demonstrate that the description of physical states and observables invoked by Chandrasekaran et al. [1] is equivalent to the Page-Wootters formalism, leading to the informal slogan “PW = CLPW”. It is our hope that this paper will help motivate a long overdue union between the QRF and quantum gravity communities. Further details will appear in a companion paper.

Julian Vuyst

Stefan Eccles

Philipp Höhn

Canada

Josh Kirklin

Gravitational entropy is observer-dependent

The study of leptoquarks and their couplings to fermions with different chiralities provides a powerful tool for distinguishing among different leptoquark models. As a case study, we focus on two specific third-generation scalar leptoquark models, $\textit{S}$ and $\textit{R}$ , which differ in their electroweak quantum numbers and chiral structures of couplings to the top quark, leading to distinct top-quark polarization states. To enhance the efficacy of the analysis, we employ jet substructure techniques like Soft Drop, $\textit{N}$-subjettiness, and our custom $\textit{b}$-tagging method, along with other event variables. The analysis has been performed using both fixed radius and dynamic radius jet clustering algorithms. A multivariate analysis using a boosted decision tree (BDT) is performed to isolate signal from the Standard Model background. For a leptoquark mass of 1250 GeV, the analysis achieves a signal significance of up to 5$\textit{.}$3 $\textit{σ}$ at the 14 TeV HL-LHC. Furthermore, a $\textit{CL}$ -based profile likelihood estimator is applied to polarization-sensitive variables to discriminate between the two models. To enhance separation between the two models, an additional BDT classifier score is obtained by training a BDT network to distinguish between the $\textit{S}$ and $\textit{R}$ models. In the chosen signal region, the BDT classifier score provides a separation score of up to 3$\textit{.}$2 $\textit{σ}$, outperforming traditional variables such as $\textit{E}$ /$\textit{E}$ and cos $\textit{θ}$ .

India

Anupam Ghosh

Partha Konar

Tousik Samui

Ritesh Singh

Jet substructure probe on scalar leptoquark models via top polarization

We report on the complete computation of the mixed QCD-electroweak corrections to the neutral-current Drell-Yan process. Our calculation holds in the entire range of dilepton invariant masses. We present phenomenological results for several kinematical distributions in the case of bare muons both in the resonant region and for high invariant masses. We also consider the forward-backward asymmetry, which is a key observable to measure the weak mixing angle. We finally extend our calculation to dressed leptons and compare our results in the massless limit to those available in the literature.

Tommaso Armadillo

Roberto Bonciani

Luca Buonocore

Simone Devoto

Massimiliano Grazzini

Stefan Kallweit

Narayan Rana

Alessandro Vicini

Mixed QCD-EW corrections to the neutral-current Drell-Yan process

Linear Standard Model (SM) extensions, defined as new particles that can couple linearly to SM fields, form a motivated and finite set of simplified models for exploring phenomenology Beyond the SM (BSM). Heavy BSM particles may be integrated out to obtain their low-energy effects in the SM Effective Field Theory (SMEFT) parametrised by the Wilson coefficients of higher-dimensional operators. We compute and map the dimension-6 SMEFT operator structure of all scalar and fermion linear SM extensions up to one-loop order, thus extending the existing tree-level dictionary of results. Explicit analytic matching expressions for the Wilson coefficients are provided as both Python and Mathematica code in a GitHub repository accessible through links embedded in our main table for each coefficient and within a Python package. We apply our map to highlight the sensitivity to heavy new physics of a $\textit{Z}$-pole run at a future Tera-$\textit{Z}$ factory; at one loop, with unit couplings, all linear SM extensions can be indirectly probed by electroweak precision measurements up to $$ \mathcal{O}(10) $$ TeV.

Australia

John Gargalionis

Jérémie Quevillon

Pham Vuong

Tevong You

Linear Standard Model extensions in the SMEFT at one loop and Tera-$\textit{Z}$

We construct supersymmetric rotating AdS black holes in 5d $$ \mathcal{N} $$ = 2 gauged supergravity coupled to two vector multiplets and a universal hypermultiplet, and verify their microscopic counting from the superconformal index of the dual 4d class $$ \mathcal{S} $$ $$ \mathcal{N} $$ = 1 SCFTs. From the CFT, we perform the Legendre transform of the index to the microcanonical ensemble. The theories are parametrized by a rational number $\textit{z}$ which enters into the extremization equations making them more challenging to solve. We present a method to address these difficulties and highlight the subtleties involved. From the gravity perspective, we identify a charged, rotating black hole whose Bekenstein-Hawking entropy matches the prediction from the index for $\textit{z}$ = ±1. Beyond this value, where hypermultiplet scalars are nonzero, we construct the near-horizon extremal geometry perturbatively around $\textit{z}$ = 1 and verify that the entropy is consistent with the CFT prediction. We discuss the thermodynamics and verify the near-horizon versions of the first law of thermodynamics and the supersymmetric condition. In this setting, our analysis characterizes the first construction of a rotating black hole geometry in a 5d $$ \mathcal{N} $$ = 2 supergravity theory that contains hypermultiplets.

Marina David

Annelien Vekemans

Microstates of AdS