From the classical $$ \mathrm{SO}\left(\mathcal{N}=8\right) $$ extended superconformal algebra between the lowest $$ \mathcal{N}=8 $$ multiplet in two dimensions obtained by Ademollo et al. (1976), we generalize it for the arbitrary $$ \mathcal{N}=8 $$ multiplet with manifest SU(8) symmetry containing the bosonic $\textit{w}$ algebra. By modifying this $$ \mathcal{N}=8 $$ supersymmetric $\textit{w}$ algebra in two dimensions, we propose a consistent celestial soft current algebra between the graviton, the gravitinos, the graviphotons, the graviphotinos, and the scalars in the $$ \mathcal{N}=8 $$ supergravity theory with SO(8) (or SU(8)) global symmetry in four dimensions initiated by de Wit and Freedman (at Stony Brook in 1977). The twenty five couplings in this celestial algebra can be written in terms of eight arbitrary couplings via the Jacobi identity.

South Korea

Changhyun Ahn

Man Kim

Toward A celestial soft symmetry algebra in the $$ \mathcal{N}=8 $$ supergravity

The internal structure of the Standard Model implies a natural ℤ × ℤ discrete gauge symmetry. Cancellation of the corresponding Dai-Freed anomalies requires the introduction of three right-handed neutrinos and three additional Majorana fermions $\textit{χ}$ . This gauge symmetry forbids the decay of the lightest fermion $\textit{χ}$ into Standard Model particles, rendering it automatically stable and providing a dark matter candidate without introducing an $\textit{ad hoc}$ stabilizing symmetry and domain-wall problem. The mass of $\textit{χ}$ is generated by the vacuum expectation value of a singlet scalar near the electroweak scale, naturally realizing a weakly interacting massive particle (WIMP) freeze-out scenario. Dark matter annihilation proceeds through scalar mediation, allowing the observed relic abundance to be reproduced while remaining consistent with current direct-detection constraints. It naturally realizes the secluded dark matter scenario and can be further tested in the next generation of experiments.

Japan

Jie Sheng

China

Tsutomu Yanagida

United States

Kairui Zhang

WIMP dark matter from a natural discrete gauge symmetry in the Standard Model

This work presents a proof of concept for MUSIC, a multi-purpose detector conceived for high-precision and ultra-high-energy physics studies in the challenging environment of $$\sqrt{s}=10$$ TeV muon–antimuon collisions. The detector features a central tracking system, electromagnetic and hadronic calorimeters, and dedicated muon detectors. This paper outlines the main design elements of each subdetector, with an emphasis on the effects of machine-induced backgrounds and the reconstruction strategies employed for key physics objects. Performance results for electrons, photons, muons, and jets are reported, and studies of jet flavour identification are discussed.

Italy

Paolo Andreetto

Nazar Bartosik

Andrea Bersani

Switzerland

Daniele Calzolari

Massimo Casarsa

Vittoria Ciccarella

Elisa Meco

Ruben Gargiulo

Alessio Gianelle

Carlo Giraldin

United Kingdom

Karol Krizka

Anton Lechner

Luigi Longo

Donatella Lucchesi

Leonardo Palombini

Nadia Pastrone

Ivano Sarra

Lorenzo Sestini

Rosamaria Venditti

Davide Zuliani

Music: a multi-purpose detector concept for physics at the 10 TeV muon collider

We build a model of lepton flavor in a slice of AdS . We add to the 5D SM fields a set of neutrino fields, as well as a horizontal U(1) symmetry and a flavon field, all propagating in the bulk. The electroweak and U(1) symmetries are spontaneously broken by a potential localized on the infrared boundary. We show that in a flavor anarchic scenario, by suitable choice of the 5D masses and the U(1) charges, the masses of the SM leptons and the PMNS matrix can be naturally generated. The neutrino masses are Dirac like, with a normal ordered hierarchical spectrum, $$ \Delta {m}_{32}^2\approx {m}_3^2,\Delta {m}_{21}^2\approx {m}_2^2\gg {m}_1^2 $$ , and a suppressed $\textit{θ}$ mixing angle. We find configurations where the charged lepton mixing angles are suppressed by powers of the Cabibbo angle ($\textit{λ}$ ) relative to vanilla anarchic partial compositeness, consequently reducing CP and lepton flavor violation. Specifically, the Wilson coefficient for the electron electromagnetic dipole moment exhibits $$ {\lambda}_C^2 $$ suppression, while those governing $\textit{μ}$ → $\textit{eγ}$ and $\textit{μ}$ − $\textit{e}$ vector operators are suppressed by $$ {\lambda}_C^{3/2} $$ compared to the anarchic scenario without U(1) horizontal symmetry.

Argentina

Leandro Rold

Franco Gigena

Jaime Guzmán Guerrero

Lepton flavor from a horizontal symmetry in a slice of AdS 5

<p>The thermodynamic geometry of the hadron resonance gas model with (without) excluded volume effects (EVE) of baryons is investigated. The case with imaginary <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>μ</mi></math>, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>μ</mi></math> is the baryon chemical potential, is investigated as well as the one with real <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>μ</mi></math>. We calculate the scalar curvature <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>R</mi></math> and use the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>R</mi><mo>=</mo><mn>0</mn></math> criterion to investigate the phase structure in the <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msup><mi>μ</mi><mn>2</mn></msup><mo>−</mo><mi>T</mi></math> plane where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>T</mi></math> is the temperature. The curve on which <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>R</mi><mo>=</mo><mn>0</mn></math> continues analytically from the imaginary <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>μ</mi></math> region, where the lattice QCD is feasible, to the real <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>μ</mi></math> one. In the presence of EVE, there are rich phase structures in the large real <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>μ</mi></math> region as well as the Roberge-Weiss-like region where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>μ</mi></math> is imaginary and a singularity appears, while there is no phase structure in the large real <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>μ</mi></math> region in the absence of EVE. The limiting temperature of the baryon gas is also obtained by using the baryon number fluctuation. The LQCD predicted critical point locates almost on the curve of the limiting temperature we determined. A simple empiric sufficient condition, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>n</mi><mi mathvariant="normal">B</mi></msub><mo>&gt;</mo><mn>1</mn><mo>/</mo><mo stretchy="false">(</mo><mn>2</mn><msub><mi>v</mi><mi mathvariant="normal">B</mi></msub><mo stretchy="false">)</mo></math>, is obtained for the quark deconfinement in the large real <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>μ</mi></math> region, where <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>n</mi><mi mathvariant="normal">B</mi></msub></math> and <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>v</mi><mi mathvariant="normal">B</mi></msub></math> are the net baryon number density and the volume of a baryon, respectively.</p>

Riki Oshima

Hiroaki Kouno

Azerbaijan

Motoi Tachibana

Kouji Kashiwa

Thermodynamic geometry in the hadron resonance gas model at real and imaginary baryon chemical potential and a simple sufficient condition for quark deconfinement

Quantum tomography of tau lepton pairs produced at a Higgs factory collider will enable measurements of their spin correlations arising from quantum entanglement. Such measurements rely on the ability to measure the components of and correlations between the taus’ spins. We present a method to fully reconstruct the kinematics of tau pair events at an electron-positron Higgs factory collider, making use of measured particles’ momenta and impact parameters. This procedure results in several consistent solutions per event, which can be assigned weights according to various event properties. Full kinematic reconstruction allows the optimal extraction of the taus’ spin orientation via polarimeters. We estimate the precision with which polarimeters can be reconstructed in an ideal detector, and quantify the effects of more realistic detector performance. We conclude that for this analysis, achieving a photon angular resolution of around 0.1 mrad is the most crucial aspect of detector performance, while photon energy resolution and vertex detector performance are significantly less important.

Daniel Jeans

Experimental aspects of the quantum tomography of tau lepton pairs at a Higgs factory collider

We investigate the structural and physical properties of a strange star admixed with self-interacting bosonic dark matter within a unified thermodynamic framework. The total energy density is modelled as a weighted combination of quark matter and dark matter components regulated by a fixed local volume fraction, corresponding to the $\textit{coextensive limit}$ in which both the components share the same spacetime geometry and extend to a common radius ( $$R_D = R_Q=R$$ ). The quark component is described by a linear equation of state (EOS), while the dark matter follows a mean-field EOS with repulsive self-interactions. By combining these EOSs into a barotropic effective EOS derived from a unified thermodynamic potential, the two-fluid system is reformulated as a thermodynamically closed and mechanically equilibrated configuration. The construction preserves the dynamical distinction between the quark and dark sectors but treats them as a macroscopically unified mixture governed by a single hydrostatic equilibrium equation. This framework identifies the fully coextensive limit of two-fluid models as a physically meaningful and thermodynamically closed configuration and provides a coherent macroscopic closure linking dark matter-strange matter microphysics to stellar observables. Using the effective EOS, we solve the Tolman–Oppenheimer–Volkoff (TOV) equations to obtain the mass–radius relationship by varying the fixed local dark matter fraction, dark matter particle mass and self-coupling constant. Our results reveal distinct modifications to the $$M-R$$ profiles, suggesting observable signatures that could offer insights into the impacts of dark matter in extreme astrophysical environments. We note that even a modest dark matter admixture softens the equation of state, thereby shrinking the maximum mass limit and hence can explain a wide range of ultra-compact stars. In particular, our study provides a possible explanation and a radius estimate for ultra-compact stars with small radii, such as XTE J1814-338, as well as for heavier pulsars like PSR J0348+0432, PSR J0740+6620, and PSR J0952-0607.

India

Samstuti Chanda

Ranjan Sharma

A unified thermodynamic framework for coextensive dark matter admixed strange stars

A correction to this paper has been published: https://doi.org/10.1007/JHEP11(2012)010

Germany

Ioan Ghişoiu

Chile

York Schröder

Erratum to: A new method for taming tensor sum-integrals

We present a generalized phenomenological parameterization of the deceleration parameter $\textit{q}$($\textit{z}$) that incorporates an effective radiative component (ERC) in addition to a localized late-time contribution. The proposed framework extends previous two-parameter $\textit{q}$($\textit{z}$) reconstructions by explicitly regulating the high-redshift behavior while preserving the late-time transition dynamics. We constrain the free parameters $$(h, q_0, z_c, z_e)$$ using late-time observational data from cosmic chronometers (CC), Pantheon+ Type Ia supernovae (SNIa), H galaxies (HIIG), and intermediate-luminosity quasars (QSO). For the full data combination (CC+SNIa+HIIG+QSO), we obtain $$q_0 = -0.25^{+0.04}_{-0.04}$$ and a transition redshift $$z_T \simeq 0.80$$ , indicating a currently accelerating Universe with a transition occurring earlier than in the $$\Lambda $$ CDM model. Within the redshift range probed by the data, the reconstructed $\textit{q}$($\textit{z}$) deviates from the $$\Lambda $$ CDM trend, reduction of the late-time acceleration. Furthermore, the reconstruction favors a relatively high value of the Hubble parameter, $$h = 0.729 \pm 0.006$$ . The ERC remains weakly constrained by late-time data but ensures a smooth and monotonic evolution of $\textit{q}$($\textit{z}$), $\textit{j}$($\textit{z}$), and $$w_\textrm{eff}(z)$$ across a wide redshift range. Within the observed interval, the model effectively reproduces the late-time behavior of the previous parametrization, while providing a controlled extension toward early epochs. Our results show that current low- and intermediate-redshift data are compatible with a reduced late-time acceleration.

Mexico

Tomás Verdugo

Alberto Hernández-Almada

Miguel García-Aspeitia

Juan Magaña

Verónica Motta

Reconstructing the cosmic expansion with a generalized q(z) parameterization: a decelerating Universe from late-time constraints

We investigate quasi-periodic oscillations (QPOs) as a diagnostic tool for probing frame-dragging effects and accretion disk physics in the spacetime of a rotating regular magnetic black hole (BH). Specifically, we analyze the precession of bound orbits and the epicyclic oscillations of test-particles under small perturbations in the equatorial plane. We demonstrate how the BH’s nonminimal coupling parameter ( $$\lambda /M^4$$ ) and dimensionless magnetic charge ($\textit{Q}$/$\textit{M}$) significantly influence the three fundamental epicyclic frequencies. By applying the relativistic precession model and employing Markov Chain Monte Carlo simulations (MCMC), we constrain the BH’s characteristic parameters, including mass, spin, magnetic charge, and nonminimal coupling, with the use of observational QPO data from five X-ray binaries: $$GRO J1655-40$$ , $$XTE J1859+226$$ , $$H1743-322$$ , $$XTE J1550-564$$ , and $$GRS 1915+105$$ . Furthermore, we examine the Lense-Thirring, geodetic, and general spin precession frequencies of a test gyroscope attached to a stationary observer around the current BH. Our theoretical results indicate that the regular charged BH suppresses these precession frequencies compared with the Kerr BH case.

R. Ali

Meng-He Wu

Hong Guo

Xiao-Mei Kuang

Precessions and parameter constraints from quasiperiodic oscillations in a rotating charged black hole