Publications

2026

• A Duality Web for Non-Supersymmetric Strings
  
  • Baykara Zihni Kaan
  • Delgado Matilda
  • Dudas Emilian
  • de Freitas Hector Parra
  • Vafa Cumrun
  , 2026. Motivated by the recently proposed geometric descriptions of 0A and 0B in M-theory and F-theory, we propose a web of duality among non-supersymmetric strings. In particular we argue that the distinct $\mathbb{Z}_2$ quotients of M-theory on $S^1\vee S^1$ lead to both 0A orientifolds as well as non-supersymmetric 10d heterotic vacua of the E-type, including the tachyon-free $SO(16)\times SO(16)$ strings. Moreover we identify certain $\mathbb{Z}_2$ quotients of F-theory on $(S^1\vee S^1)\times S^1$ with 0B orientifolds (including a tachyon-free model) as well as others with dual to non-supersymmetric heterotic strings of the D-type. Moreover using this picture we resolve some puzzles and provide further evidence for the Bergman-Gaberdiel duality between a particular 0B orientifold in 10 dimensions and the Narain compactification of 26-dimensional bosonic strings on a 16-dimensional torus, as well as the DMS conjecture of a 0A orientifold duality in 10d with a bosonic string orientifold of a Narain compactification to 10d.
• On the robustness of Mann-Kendall tests used to forecast critical transitions
  
  • Gamot Tristan
  • Thibeau--Sutre Nils
  • van Dooren Tom
  , 2026. Non-parametric approaches to test for trends in time series make use of the Mann-Kendall statistic. Based on asymptotic arguments, these tests assume that its distribution follows a Gaussian distribution, even for autocorrelated time series. Recent results on the lack of validity of this assumption urge a robustness analysis of these approaches. While the issue is relevant across a wide range of applications, we illustrate it here in the context of detecting early warning signals (EWS) of critical transitions, which are used across a variety of research domains, and where commonly applied methods generate autocorrelation. We present a broad analysis, covering all types of critical transitions commonly investigated in EWS studies. We compare empirical distributions of the Mann-Kendall statistic computed from classical EWS indicators preceding critical transitions to the theoretical distributions hypothesized by Mann-Kendall tests. We detect mismatches leading to inflated type I error rates, which would routinely lead to announcing a critical transition while it is not occurring. In contrast to a recent recommendation, we conclude that the use of Mann-Kendall tests for trend detection in the context of forecasting critical transitions should be avoided. We point out several alternative methods available instead. (10.48550/arXiv.2604.15230)
  DOI : 10.48550/arXiv.2604.15230
• Full energy fraction and angular dependence of medium-induced splittings in the large-$N_c$ limit
  
  • Andres Carlota
  • Dominguez Fabio
  , 2026. Jets produced in relativistic heavy-ion collisions are modified by their interactions with the quark-gluon plasma (QGP), making jet substructure observables sensitive probes of QGP dynamics. A quantitative description of these modifications requires understanding how the medium affects elementary parton splittings with full dependence on both their energy fraction $z$ and splitting angle $θ$, beyond the widely used soft emitted-gluon approximation. Here, we study medium-induced $1 \to 2$ splittings double-differential in $z$ and $θ$, with full resummation of multiple scatterings, and show that in the large-$N_c$ limit and under the harmonic oscillator (HO) approximation, all path integrals can be evaluated analytically for any splitting channel, providing a computationally efficient semi-analytical result. We also revisit the semi-hard approximation (SHA), extending it to include leading corrections in inverse powers of the partons energies, which we denote the improved semi-hard approximation (ISHA), and assess its validity through a comparison with the large-$N_c$-HO results. Our analysis shows that while the SHA is found to be unreliable across most of phase space, even for high-energy emitters, the ISHA provides a robust approximation for splittings where all partons are sufficiently energetic.
• Deeply virtual meson production at HERA and at the EIC within the Color Glass Condensate EFT
  
  • Boussarie Renaud
  • Delle Rose Luigi
  • Fucilla Michael
  • Papa Alessandro
  • Szymanowski Lech
  • Wallon Samuel
  , 2026. Continuing our previous study of Deeply Virtual Meson Production (DVMP) at twist-3 accuracy, we derive compact expressions for all helicity amplitudes. We perform a phenomenological analysis of the helicity-amplitude ratio $\mathcal{A}^{11}/\mathcal{A}^{00}$ and of the spin-density matrix element $r_{00}^{04}$ within the Color Glass Condensate framework. Small-$x$ evolution is incorporated by numerically solving the running-coupling-and-collinearly-improved Balitsky-Kovchegov and Balitsky-Fadin-Kuraev-Lipatov equations with the McLerran-Venugopalan model as the initial condition. By capturing a relevant subset of next-to-leading order corrections, we provide the most theoretically accurate description of these observables to date. Our results are compared to HERA data, and predictions are presented for electron-lead collisions at the future Electron-Ion Collider. We discuss the impact of non-linear effects at low photon virtuality and the role of genuine higher-twist contributions associated with light vector meson distribution amplitudes, corresponding to higher-Fock-state components of the projectile.
• Scalable Ground-State Certification of Quantum Spin Systems via Structured Noncommutative Polynomial Optimization
  
  • Wang Jie
  • Jansen David
  • Frerot Irénée
  • Renou Marc-Olivier
  • Magron Victor
  • Acín Antonio
  , 2026. A fundamental challenge in quantum physics is determining the ground-state properties of manybody systems. Whereas standard approaches, such as variational calculations, consist of writing down a wave function ansatz and minimizing over the possible states expressible by this ansatz, one can alternatively formulate the problem as a noncommutative polynomial optimization problem. This optimization problem can then be addressed using a hierarchy of semidefinite programming relaxations. In contrast to variational calculations, the semidefinite program can provide lower bounds for ground state energies and upper and lower bounds on observable expectation values. However, this approach typically suffers from severe scalability issues, limiting its applicability to small-to-medium-scale systems. In this article, we demonstrate that leveraging the inherent structures of the system can significantly mitigate these scalability challenges and thus allows us to compute meaningful bounds for quantum spin systems on up to 16 × 16 square lattices.
• White paper on the relevance of the European Solar Telescope (EST) for the French heliophysics community
  
  • Pariat Etienne
  • Noraz Quentin
  • Perri Barbara
  • Poirier Nicolas
  • Froment C.
  • Bigot Lionel
  • Aulanier Guillaume
  • Gelly Bernard
  • Aboudarham Jean
  • Aizawa Sae
  • Alexandrova Olga
  • Alqeeq Soboh
  • Amari Tahar
  • Auchère Frédéric
  • Bernoux Guillerme
  • Berthomier Matthieu
  • Bommier Veronique
  • Bonnin Xavier
  • Brun Allan Sacha
  • Bualé Isabelle
  • Buchlin Éric
  • Canou Aurélien
  • Canu Patrick
  • Corbard Thierry
  • Cornu Florence
  • Coustillet Camille
  • Cozzani Giulia
  • D’herbomez Léa
  • Diaz Castillo Saida
  • Dudok de Wit Thierry
  • Faurobert Marianne
  • Finley Adam
  • Fontaine Dominique
  • Garcia Rafael A.
  • Grappin Roland
  • Hadid Lina
  • Henadhira Arachchige Kalpa Harindra Perera
  • Janvier Miho
  • Jouve Laurène
  • Kieokaew Rungployphan
  • Kirkwood Hannah
  • Lavraud Benoit
  • Le Breton Jean-Pierre
  • Le Contel Olivier
  • Le Nestour Nicolas
  • Leblanc François
  • Masson Sophie
  • Meyer-Vernet Nicole
  • Parenti Susanna
  • Pitout Frédéric
  • Rieutord Michel
  • Romero Castañeda Jorge
  • Rouillard Alexis
  • Ruiz de Galarreta Claudia
  • Sahraoui Fouad
  • Schmieder Brigitte
  • Simon Pauline
  • Strugarek Antoine
  • Tallon Michel
  • Thepthong Panisara
  • Touresse Jade
  • Vial Jean-Claude
  • Vilmer Nicole
  • Zaslavsky Arnaud
  , 2026. The project of the European Solar Telescope aims to provide a state-of-the art infrastructure to study the Sun and its interactions with Earth and the heliosphere. This 4.2m aperture telescope will be equipped with multi conjugate adaptive optics, light-polarisation analyser, imaging spectrograph and integral field unit spectrographs. It will provide unprecedented observations of the solar photosphere and chromosphere and of the dynamical events and features that pertains to the low solar atmosphere. The EST project is presently in a phase of crystallisation, aiming at the creation of an European Research Infrastructure Consortium. While the French community has continuously been associated with the development of the EST project, some specific scientific aspects are more particularly relevant for the French astrophysics and heliophysics communities. The present review highlights the scientific research axes of high interest from the French community that shall strongly benefit from EST. The later will not only advance numerous topics of solar physics, as well as solar adaptive optics developments, but will also provide unrivaled datasets of high interest in the framework of space weather. This review also aims to highlight the space weather use that can be done with future EST observations, that will be particularly relevant for French heliophysicists.
• M-theory on $S^1\vee S^1$ as Type 0A
  
  • Baykara Zihni Kaan
  • Dudas Emilian
  • Vafa Cumrun
  , 2026. We propose an exotic geometric M-theory dual for the weak coupling Type 0A string: compactification on a sub-Planckian $S^1\vee S^1$ (two circles connected at a point), where strong quantum effects lead to fields living on distinct resolutions of that space. Moreover we argue that tachyon condensation of the 0A theory corresponds to shrinking of one of the two circles leading to the IIA supersymmetric string. We use this and other dualities to provide an F-theoretic description of the axio-dilaton and the tachyonic field of Type 0B and argue for the existence of a strong coupling critical point of the potential using the resulting duality symmetry $Γ_0(2)\subset SL(2,\mathbb{Z})$. The existence of this critical point can also be argued using conventional M-theory dualities. If this critical point is unique it is an unstable dS vacuum. Using this we propose a strong coupling conformal fixed point for a non-supersymmetric gauge theory in four dimensions living on coincident $D3^+-D3^-$branes of 0B.
• M-theory on $S^1\vee S^1$ as Type 0A
  
  • Baykara Zihni Kaan
  • Dudas Emilian
  • Vafa Cumrun
  , 2026. 33 pages
• From path integral quantization to stochastic quantization: a pedestrian's journey
  
  • Benedetti Dario
  • Chevyrev Ilya
  • Gurau Razvan
  , 2026. We give two novel proofs that the path integral and stochastic quantizations of generic scalar Euclidean quantum field theories are equivalent. Our proofs rely on Taylor interpolations indexed by forests, in the fashion of constructive field theory. The first proof works at the level of individual terms in the Feynman expansion, with the forests appearing as spanning forests in Feynman graphs. The second one works at the level of the path integral and avoids the full expansion of the Feynman perturbation series.
• Higher dualities in E$_{11}$ exceptional field theory
  
  • Bossard Guillaume
  • Boulanger Nicolas
  • O'Connor Josh
  , 2026. It has been conjectured that there exists an E11-invariant formulation of eleven-dimensional supergravity in which the propagating fields of the theory are realised through an infinite tower of higher duals. In this work, we prove this conjecture explicitly within E11 exceptional field theory at the linearised level. Starting from the pseudo-Lagrangian, we construct parent actions for all higher gradient dual fields that are associated with the three-form, the six-form, and the dual graviton. We show that the resulting Euler-Lagrange equations constrain the Stueckelberg fields to be pure curls, ensuring that the higher duals propagate the same physical degrees of freedom as the original supergravity fields. The additional Stueckelberg fields, which are not predicted by the tensor hierarchy algebra, are shown to play a specific role as sources for the Labastida tensors of the higher dual fields.
• Interplay between the chiral and deconfinement transitions from a Curci-Ferrari-based Polyakov loop potential
  
  • Mari Surkau V. Tomas
  • Reinosa Urko
  , 2026. We couple the two-flavor Nambu--Jona-Lasinio model to a gluonic background corresponding to the gauge-field expectation value in the center-symmetric Landau gauge. Low-energy features in this gauge are captured by a center-symmetric extension of the Curci-Ferrari model and provide a good grasp on key aspects of the confinement/deconfinement transition. Within this framework, we can investigate the interplay between the chiral and deconfinement transitions. Compared to other approaches based on multi-parameter Ansätze of the Polyakov loop potential fixed from comparison to finite-temperature lattice data, the modeling of the glue sector in the present set-up depends on only one phenomenological parameter that can be fixed by comparison to lattice data in the vacuum. We detail the structure of the phase diagram, with special emphasis on the finite density axis, and compute thermodynamical observables relevant for applications. We also highlight the properties of the recently introduced net quark number response of the medium as a sensible probe of the phases of QCD, in particular as a tool to disambiguate the nature of certain regions of the phase diagram where the use of the Polyakov loops could lead to misinterpretations. Finally, we critically assess the sensitivity of our results to the various parameters, both in the glue sector and in the chiral sector.
• Hard exclusive photoproduction of photon-meson pairs: pseudoscalar channels π, η and η
  
  • Crnković Nikola
  • Duplančić Goran
  • Nabeebaccus Saad
  • Passek-K. Kornelija
  • Pire Bernard
  • Szymanowski Lech
  • Wallon Samuel
  Physical Review D, American Physical Society, 2026, 113, pp.034001.
• Observation of emergent scaling of spin–charge correlations at the onset of the pseudogap
  
  • Chalopin Thomas
  • Bojović Petar
  • Wang Si
  • Franz Titus
  • Sinha Aritra
  • Wang Zhenjiu
  • Bourgund Dominik
  • Obermeyer Johannes
  • Grusdt Fabian
  • Bohrdt Annabelle
  • Pollet Lode
  • Wietek Alexander
  • Georges Antoine
  • Hilker Timon
  • Bloch Immanuel
  Proceedings of the National Academy of Sciences of the United States of America, National Academy of Sciences, 2026, 123 (4), pp.e2525539123. In strongly correlated materials, interacting electrons are entangled and form collective quantum states, resulting in rich low-temperature phase diagrams. Notable examples include cuprate superconductors, in which superconductivity emerges at low doping out of an unusual “pseudogap” metallic state above the critical temperature. The Fermi–Hubbard model, describing a wide range of phenomena associated with strong electron correlations, still offers major computational challenges despite its simple formulation. In this context, ultracold atoms quantum simulators have provided invaluable insights into the microscopic nature of correlated quantum states. Here, we use a quantum gas microscope Fermi–Hubbard simulator to explore a wide range of dopings and temperatures in a regime where a pseudogap is known to develop. By measuring multipoint correlation functions up to fifth order, we uncover a universal scaling behavior in magnetic and higher-order spin–charge correlations characterized by a doping-dependent temperature scale. Accurate comparisons with determinant Quantum Monte Carlo and Minimally Entangled Typical Thermal States simulations confirm that this temperature scale is comparable to the pseudogap temperature T ∗ . Our quantitative findings reveal a qualitative behavior of magnetic properties and spin–charge correlations in an emergent pseudogap and pave the way toward the exploration of charge pairing and collective phenomena expected at lower temperatures. (10.1073/pnas.2525539123)
  DOI : 10.1073/pnas.2525539123
• Accessing baryon-antibaryon generalized distribution amplitudes in $e^{\pm} γ\to e^{\pm} B \bar{B} $
  
  • Han Jing
  • Pire Bernard
  • Song Qin-Tao
  Physical Review D, American Physical Society, 2026, 113, pp.014027. γ∗γ→BB¯ is the golden process to access chiral-even di-baryon generalized distribution amplitudes (GDAs) as deeply virtual Compton scattering has proven to be for the generalized parton distributions. In the framework of colinear QCD factorization where the leading twist amplitude is the convolution of GDAs and a perturbatively calculable coefficient function, we study the scattering amplitude for the baryonic channels where B is a spin 1/2 baryon such as the nucleon or hyperon Λ,Σ. Taking into account the interfering QED amplitude, we calculate the cross section of the e±γ→e±BB¯ process that can be experimentally studied in e−e+ as well as in electron-ion facilities. We explore both the final state polarization summed case and the polarization dependent effects. Numerical estimates are presented for e−γ→e−pp¯, using motivated models for GDAs. Our results show that a first extraction of baryon-antibaryon GDAs from experimental measurements is feasible at Belle II. (10.1103/6zmf-wd76)
  DOI : 10.1103/6zmf-wd76
• When Less is More: Approximating the Quantum Geometric Tensor with Block Structures
  
  • Shokry Ahmedeo
  • Santini Alessandro
  • Vicentini Filippo
  , 2025. The natural gradient is central in neural quantum states optimizations but it is limited by the cost of computing and inverting the quantum geometric tensor, the quantum analogue of the Fisher information matrix. We introduce a block-diagonal quantum geometric tensor that partitions the metric by network layers, analogous to block-structured Fisher methods such as K-FAC. This layer-wise approximation preserves essential curvature while removing noisy cross-layer correlations, improving conditioning and scalability. Experiments on Heisenberg and frustrated $J_1$-$J_2$ models show faster convergence, lower energy, and improved stability. (10.48550/arXiv.2510.08430)
  DOI : 10.48550/arXiv.2510.08430
• Classically Prepared, Quantumly Evolved: Hybrid Algorithm for Molecular Spectra
  
  • Santini Alessandro
  • Barison Stefano
  • Vicentini Filippo
  , 2025. We introduce a hybrid classical-quantum algorithm to compute dynamical correlation functions and excitation spectra in many-body quantum systems, with a focus on molecular systems. The method combines classical preparation of a perturbed ground state with short-time quantum evolution of product states sampled from it. The resulting quantum samples define an effective subspace of the Hilbert space, onto which the Hamiltonian is projected to enable efficient classical simulation of long-time dynamics. This subspace-based approach achieves high-resolution spectral reconstruction using shallow circuits and few samples. Benchmarks on molecular systems show excellent agreement with exact diagonalization and demonstrate access to dynamical timescales beyond the reach of purely classical methods, highlighting its suitability for near-term and early fault-tolerant quantum hardware.
• Looking elsewhere: improving variational Monte Carlo gradients by importance sampling
  
  • Misery Antoine
  • Gravina Luca
  • Santini Alessandro
  • Vicentini Filippo
  Machine Learning : Science and Technology, IOP Publishing Ltd, 2026. Neural-network quantum states (NQS) offer a powerful and expressive ansatz for representing quantum many-body wave functions. However, their training via Variational Monte Carlo (VMC) methods remains challenging. It is well known that some scenarios -such as sharply peaked wave functions emerging in quantum chemistry -lead to high-variance gradient estimators hindering the effectiveness of variational optimizations. In this work we investigate a systematic strategy to tackle those sampling issues by means of adaptively tuned importance sampling. Our approach is explicitly designed to target the gradient estimator instead of the loss function and be computationally inexpensive. We benchmarked our approach across the ground-state search of a wide variety of hamiltonians, including frustrated spin systems and ab-initio quantum chemistry. Overall, our approach can reduce the computational cost of vanilla VMC considerably, up to a factor of 100x when targeting highly peaked quantum chemistry wavefunctions. (10.1088/2632-2153/ae387f)
  DOI : 10.1088/2632-2153/ae387f
• Schwarzian quantum corrections to shear correlators of the near-extremal Reissner-Nordström-AdS black hole
  
  • Goutéraux Blaise
  • Ramirez David M
  • Supiot Clément
  , 2026. Near-AdS$_2$ spacetimes are controlled by a Schwarzian effective dual theory. The Kaluza-Klein reduction of higher-dimensional black holes shows that the Schwarzian generates a logarithmic contribution to the entropy, thereby resolving a long-standing puzzle in near-extremal black hole thermodynamics. Here, we leverage exact results for quantum-corrected, Schwarzian scalar correlation functions in order to evaluate the impact of bulk quantum fluctuations on the low-temperature shear correlators of the state dual to Reissner-Nordström-AdS$_4$ black holes with a flat, compact horizon. In the hydrodynamic regime, we find that quantum fluctuations tend to increase the shear viscosity away from $s/(4π)$, thereby preserving the Kovtun-Son-Starinets bound. Outside the hydrodynamic regime, quantum fluctuations lift the zero temperature, classical gapless modes reported in previous literature.
• Charge and spin orders in the t-U-V-J model: a slave-spin-1 approach
  
  • Simard Olivier
  • Ferrero Michel
  • Ayral Thomas
  , 2026. Strongly-correlated fermion systems on a lattice have been a subject of intense focus in the field of condensed-matter physics. These systems are notoriously difficult to solve, even with state-of-theart numerical methods, especially in regimes of parameters where degrees of freedom compete or cooperate at similar energy and length scales. Here, we introduce a spin-1 slave-particle technique to approximately treat the t-U -V -J fermionic model at arbitrary electron dopings in a simple manner. This formalism relies on a self-consistent cluster mean-field method, and it couples effective pseudo-spin and pseudo-fermion sectors, representing the original electron charge and spin degrees, respectively. We study the phase diagram of the model under various conditions and report the appearance of charge and spin stripes within this formalism. These stripes are a consequence of the cluster mean-field treatment of the pseudo-particle sectors and have not been detected in previous slave-particle studies. (10.48550/arXiv.2601.16153)
  DOI : 10.48550/arXiv.2601.16153
• Many-body Quantum Score: a scalable benchmark for digital and analog quantum processors and first test on a commercial neutral atom device
  
  • Erbin Harold
  • Burdeau Pierre-Louis
  • Bertrand Corentin
  • Ayral Thomas
  • Misguich Grégoire
  , 2026. We propose the Many-body Quantum Score (MBQS), a practical and scalable application level benchmark protocol designed to evaluate the capabilities of quantum processing units (QPUs)—both gate-based and analog—for simulating many-body quantum dynamics. MBQS quantifies performance by identifying the maximum number of qubits with which a QPU can reliably reproduce correlation functions of the transverse-field Ising model following a specific quantum quench. This paper presents the MBQS protocol and highlights its design principles, supported by analytical insights, classical simulations, and experimental data. It also displays results obtained with Ruby, an analog QPU based on Rydberg atoms developed by the Pasqal company. These findings demonstrate MBQS’s potential as a robust and informative tool for benchmarking near-term quantum devices for many-body physics. (10.48550/arXiv.2601.03461)
  DOI : 10.48550/arXiv.2601.03461
• Uncovering thermodynamic origin of counterflow and coflow instabilities in miscible binary superfluids
  
  • An Yuping
  • Gouteraux Blaise
  • Li Li
  Physical Review A, American Physical Society, 2026, 113 (1), pp.013305. In this paper, we explore instabilities in binary superfluids with a nonvanishing relative superflow, particularly focusing on counterflow and coflow instabilities. We extend recent results on the thermodynamic origin of finite superflow instabilities in single-component superfluids to binary systems and derive a criterion for the onset of instability through a hydrodynamic analysis. To verify this result, we utilize both the Gross-Pitaevskii equation (GPE) for weakly interacting Bose-Einstein condensates (BEC) and a holographic binary superfluid model, which naturally incorporates strong coupling, finite temperature, and dissipation. We find that the counterflow and coflow instabilities in binary superfluids are all essentially thermodynamic. Except the one due to order competing via global thermodynamic instability, the others are caused by an eigenvalue of the free energy Hessian diverging and changing sign. We also observe that the critical velocities of these instabilities follow a general scaling law related to the interaction strength between superfluid components. The nonlinear stages of the instabilities are also studied by full time evolution, where vortex dynamics is found to play a significant role, resulting in the reduction of superfluid velocity back to a stable phase. (10.1103/g954-ddt7)
  DOI : 10.1103/g954-ddt7
• A strong-weak duality for the 1d long-range Ising model
  
  • Benedetti Dario
  • Lauria Edoardo
  • Mazac Dalimil
  • van Vliet Philine
  SciPost Physics, SciPost Foundation, 2026, 20 (2), pp.029. We investigate the one-dimensional Ising model with long-range interactions decaying as $1/r^{1+s}$. In the critical regime, for $1/2 \leq s \leq 1$, this system realizes a family of nontrivial one-dimensional conformal field theories (CFTs), whose data vary continuously with $s$. For $s>1$ the model has instead no phase transition at finite temperature, as in the short-range case. In the standard field-theoretic description, involving a generalized free field with quartic interactions, the critical model is weakly coupled near $s=1/2$ but strongly coupled in the vicinity of the short-range crossover at $s=1$. We introduce a dual formulation that becomes weakly coupled as $s \to 1$. Precisely at $s=1$, the dual description becomes an exactly solvable conformal boundary condition of the two-dimensional free scalar. We present a detailed study of the dual model and demonstrate its effectiveness by computing perturbatively the CFT data near $s=1$, up to next-to-next-to-leading order in $1-s$, by two independent approaches: (i) standard renormalization of our dual field-theoretic description and (ii) the analytic conformal bootstrap. The two methods yield complete agreement. (10.21468/SciPostPhys.20.2.029)
  DOI : 10.21468/SciPostPhys.20.2.029
• Before the Bang: Wormholes at the Dawn of the Universe
  
  • Betzios Panos
  • Ghiringhelli Paul
  • Gialamas Ioannis D
  • Papadoulaki Olga
  Int.J.Mod.Phys.D, 2026. This essay discusses recent progress on Euclidean wormholes as candidate contributions to the Universe's initial quantum state. The comparison with the Hartle-Hawking no-boundary proposal highlights both a conceptual affinity and genuine advance: wormholes retain the relevance of Euclidean-saddles as encoders of properties of cosmological wavefunctions, while they broaden the class of regular saddles that are physically relevant for inflating universes and are capable of resolving issues that plague the no-boundary proposal. The principal achievement of the wormhole program is to enlarge the semiclassical initial-condition land-scape in a way that is physically rich, conforms with Holographic expectations and as such becomes increasingly relevant for early-universe model building, within UV complete theories of quantum gravity. (10.1142/S0218271826410166)
  DOI : 10.1142/S0218271826410166
• A Menagerie of Wormholes and Cosmologies in the Gravitational Path Integral
  
  • Betzios Panos
  • Ghiringhelli Paul
  • Gialamas Ioannis D
  • Papadoulaki Olga
  Journal of High Energy Physics, Springer, 2026, 06, pp.171. We analyse a variety of Euclidean saddles in the gravitational path integral, with asymptotic AdS boundary conditions, in a class of Einstein-Scalar-Maxwell models. These include single boundary solutions, usual and wineglass wormholes, as well as more exotic (quasi)-oscillatory saddles. Our construction shows how an unbound number of oscillations gets tamed, when flat directions of the potential get lifted. We find several interesting phase transitions between these solutions. The Euclidean wormhole backgrounds can be analytically continued to Lorentzian FLRW universes. Some of them contain an early period of inflation. We delineate the conditions under which they can be the dominant saddles in the gravitational path integral and use them to estimate ratios of probabilities for different cosmological outcomes. (10.1007/JHEP06(2026)171)
  DOI : 10.1007/JHEP06(2026)171
• Polaron-Driven Switching of Octupolar Order in Doped 5d² Double Perovskite
  
  • Fiore Mosca Dario
  • Celiberti Lorenzo
  • Pourovskii Leonid
  • Franchini Cesare
  Physical Review Letters, American Physical Society, 2026, 137 (4), pp.046504. We investigate how doping-induced small polarons impact the low-temperature multipolar orders of the 5d² double perovskite Ba₂CaOsO₆. By computing intersite exchange interactions between 5d¹ localized hole polarons and 5d² magnetic ions from first principles, we demonstrate the reversal of the dominant octupolar exchange from ferromagnetic to antiferromagnetic. Solving the corresponding effective Hamiltonian, we find this reversal to account for the progressive suppression of the ferro-octupolar order and the reduction of the ordering temperature upon Na doping. These findings clarify previously ambiguous experimental observations and demonstrate that charge doping in the form of small polarons offers a viable route to tuning intersite exchange interactions in spin-orbit-entangled materials, enabling the emergence of novel quantum orders. (10.1103/r8v5-h8bq)
  DOI : 10.1103/r8v5-h8bq