Publications

2026

• MagInt
  
  • Pourovskii Leonid
  • Fiore Mosca Dario
  , 2026. A TRIQS-based application for calculating intersite exchange interactions in correlated materials from DFT+DMFT calculations.
• D-branes and orientifolds on quasicrystalline orbifold backgrounds
  
  • Wendels Antony
  , 2026. We construct and analyse orientifold descendants of a six-dimensional type IIB $\mathbb Z_{12}$ quasicrystalline orbifold. The parent background is defined by a Narain-lattice automorphism that is not crystallographic on the geometric torus. We determine the closed-string spectrum and twisted-sector orbit structure, construct a compatible unoriented projection, and compute the Klein bottle, annulus and Möbius strip amplitudes. Tadpole cancellation selects boundary orbits that admit a partially T-dual description as D7-branes at angles and fixes the Chan-Paton gauge group and massless spectrum. The resulting supersymmetric six-dimensional vacuum satisfies the irreducible anomaly constraints, its reducible anomaly polynomial factorizes through the Green-Schwarz mechanism, and its anomaly lattice obeys the Kim-Shiu-Vafa string-probe bound. We also construct a Brane Supersymmetry Breaking descendant with a perturbatively tachyon-free rigid branch, and a freely acting five-dimensional orientifold whose two decompactification limits reproduce a geometric type IIA $\mathbb Z_3$ orientifold and an antisymmetric type IIB $\mathbb Z_4$ orientifold. These examples show that quasicrystalline closed-string backgrounds can admit controlled perturbative open-string completions with non-trivial boundary and crosscap sectors.
• AdS$_4$ Celestial Symmetries: from Ambitwistor charges to CFT$_3$ Light-Ray Operators
  
  • Goodenbour Alex
  • Kmec Adam
  • Mason Lionel
  • Ruzziconi Romain
  , 2026. The ${L}_Λw_{1+\infty}$ algebra is the cosmological-constant deformation of the celestial $Lw_{1+\infty}$ symmetry algebra of gravity, providing an infinite-dimensional extension of the three-dimensional conformal algebra at the AdS$_4$ boundary. We construct the Hamiltonian charges associated with these symmetries from boundary ambitwistor-space data, using LeBrun's Heaven on Earth correspondence, and translate them to spacetime via the Penrose transform. We relate the resulting expressions to light-ray operators in the boundary CFT$_3$, including ANEC operators, their conformal descendants, and their commutators.
• The doubly conformal dispersion relation
  
  • Ferragatta Maddalena
  • van Rees Balt C
  , 2026. We provide a simple derivation of the conformal dispersion relation of Carmi and Caron-Huot which reconstructs a CFT four-point function from its double discontinuity. We exhibit a hidden conformal symmetry which explains the appearance of the "magic variable" x as a simple cross-ratio, built from four physical cross-ratios. We also introduce a regulator in the double discontinuity operation and then prove that one subtraction suffices for all integrals to converge.
• Spin-Hall devices: spin relaxation spatially separates current injection from Joule dissipation
  
  • Qiao Yanbo
  • Saati Sariah Al
  • Wegrowe Jean-Eric
  , 2026. The stationary state of a spin Hall bar connected to an external load circuit is investigated through a variational approach based on the principle of minimum power dissipation generalized to the two-spin-channel model. The self-consistent distributions of longitudinal and transverse current densities, alongside the corresponding spin and charge accumulations and dissipation power in the resistance, are derived. Surprisingly, it is shown that the Joule dissipation vanishes when the load resistance is placed at a sufficiently large distance compared with the spin-relaxation length. Such a highly non-trivial global stationary state appears as the most striking characteristic of the injection of pure spin current compared with more usual current injection.
• Spin qubit gates via phonon buses in electron nanowires
  
  • Lewis Dylan
  • Ghosh Roopayan
  • Kumar Dr. Sanjeev
  • Pepper Michael
  • Smith Charles
  • Le Hur Karyn
  • Bose Sougato
  , 2026. <div><p>Scalable architectures for quantum computing using semiconductor quantum dots require interactions between qubits beyond adjacent quantum dots. Here, we propose using nanowires of electrons to mediate the interaction between two quantum dots. Virtual phonons in the linear chain of electrons can mediate an interaction that gives rise to effective spin-spin coupling of the electrons in distant quantum dots. We find coupling strengths of more than 30 MHz for experimentally realisable parameters in GaAs quantum dots.</p></div>
• Geometrical approach and topological electron density in the p x + ip y superconductor
  
  • Le Hur Karyn
  • Narayanan Kabir
  • Chambert Óscar Mañas
  , 2026. <div><p>We present an analysis on the geometrical and physical nature of the px + ipy superconductor on the square lattice, with an emphasis on the topological phase transition at half-filling. We develop a local topological marker from specific Dirac points within the Brillouin zone, which is introduced via the addition of two one-dimensional (1D) Z (Z2) invariants defined on the Bloch sphere. We relate this topological marker to the electron spectral function integrated on frequency through the local momentum-resolved electron density, which may be measured via Angle Resolved Photoemission Spectroscopy (ARPES), and show that it remains well-protected including temperature effects. Integrating on a small area around a specific point in momentum space associated to the measure uncertainty, this also reveals the Van Hove logarithmic profile of the density of states in the derivative of the local marker while preserving the topological information. Topological transitions correspond to a protected semi-metal. We analyse the real space representation of this topological marker from correlation functions. We present physical responses such as the topological superfluid density.</p></div>
• Decompactification and the Flat-Space Limit of AdS$_5\times$ S$^5$ Master Correlators
  
  • Eden Burkhard
  • Heslop Paul
  • Kulkarni Harshal
  • Lipstein Arthur
  • Ruzziconi Romain
  • Yelleshpur Srikant Akshay
  , 2026. We study the flat-space limit of AdS$_5$/CFT$_4$ holographic correlators while accounting for the simultaneous decompactification of the internal S$^5$. We show that this limit is naturally formulated in terms of master propagators and correlators, which resum the infinite tower of Kaluza--Klein modes. For boundary correlators, the resulting expressions can be interpreted in terms of amplitudes with kinematics restricted to 5d. We then consider master correlators whose external insertions are kept in the AdS$_5\times$S$^5$ bulk before taking the limit, and argue that they recover flat-space amplitudes with unrestricted kinematics in 10d Minkowski space. Finally, we show that the flat-space limit commutes with the boundary limit if we analytically continue the sphere so that the bulk geometry becomes AdS$_5 \times$dS$_5$, and the resulting formulae suggest an interpretation in terms of amplitudes in flat space with two time directions and with 10d kinematics satisfying two simultaneous null constraints. We discuss the implications of these constructions for flat-space holography and its relation to the Carrollian limit of the dual CFT.
• Relativistic spatial distributions of transverse angular momentum
  
  • Lorcé Cédric
  • Mukherjee Asmita
  • Singh Ravi
  • Won Ho-Yeon
  , 2026. In our previous work [C. Lorcé et al., Phys. Lett. B 868 (2025) 139792], we investigated the 2D spatial distributions of transverse total angular momentum, including orbital angular momentum and intrinsic spin, relative to the canonical center (or center of spin). In the present work, we extend this analysis in two directions. First, we study the corresponding transverse boost distributions relative to the canonical center. Second, since the definition of generalized angular momentum density depends crucially on the choice of pivot, we analyze how the spatial distributions of transverse total angular momentum and boost are modified when they are defined relative to different relativistic centers, viz.~the relativistic centers of mass, energy, and spin. Considering spin-1/2 targets, we derive the corresponding 2D spatial distributions in the transverse plane, and further investigate how the spatial patterns evolve under longitudinal Lorentz boosts. Additionally, we provide the corresponding light-front distributions in the transverse plane, establishing a clear connection between the instant-form and light-front descriptions of transverse angular momentum and boost.
• Tracing Gluon Saturation through Hadronization at EIC
  
  • Ke Weiyao
  • Liu Xu
  • Shi Yu
  • Wang Xin-Nian
  • Zhou Jian
  , 2026. Gluon saturation provides a window into the nonlinear nature of the strong interaction in nuclear matter. One direct consequence of saturation is the $\boldsymbol{k}_T$ broadening in the final state.We investigate how hadronization reshapes conventional signatures of gluon saturation at EIC within a complete event-generator framework. To this end, we implement in eHIJING an initial-state-radiation algorithm based on nonlinear small-$x$ evolution and complete the events with beam remnants, final-state radiation, and hadronization. In our simulations, the signal of parton-level nuclear $\boldsymbol{k}_T$ broadening is strongly diluted in both the nucleon energy correlator and leading-dihadron azimuthal decorrelation after hadronization. Global hadronic recoil, by contrast, remains sensitive to the underlying $\boldsymbol{k}_T$ broadening. We further demonstrate that Bayesian unfolding of the global hadronic recoil provides access to the underlying hard-scattering $\boldsymbol{k}_T$ distribution. These results establish the global hadronic recoil as a promising saturation observable at the EIC.
• Levitation and stability in maglev systems
  
  • Sayegh Peter Albert
  • Couairon Arnaud
  • Déo Hadrien
  • Abou Rabii Yazan
  European Journal of Physics, European Physical Society, 2026. We present an experimental, project-based approach to teaching classical electrodynamics through the construction and analysis of a scaled-down magnetic levitation train. Using flexible magnetic tape as a guideway, we demonstrate stable levitation and perform precise measurements of the vertical gap as a function of load. These experimental data are validated using an analytical force model derived from a dipole-layer approximation, which confirms the self-restoring vertical stability of the repulsive configuration. By bridging laboratory measurements with theoretical energy methods, students can extrapolate their scaled results to industrial parameters, successfully reproducing the passenger capacity of a full-scale commercial maglev vehicle. This project offers a tangible platform for applying core concepts such as magnetic field geometry, vector potentials, and Earnshaw’s theorem to a high-interest, real-world engineering challenge. (10.1088/1361-6404/aeaab7)
  DOI : 10.1088/1361-6404/aeaab7
• Coherent deeply virtual Compton scattering on helium-4 beyond the leading twist approximation
  
  • Martínez-Fernández V.
  • Pire B.
  • Sznajder P.
  • Wagner Jakub
  , 2026. Coherent hard exclusive reactions on light nuclei offer access to their quark and gluon structure and provide a framework for three-dimensional nuclear tomography. We analyze deeply virtual Compton scattering on a helium-4 target, including leading-twist contributions as well as kinematical twist-3 and twist-4 effects. We present numerical estimates of cross sections and asymmetries for kinematic regimes relevant to JLab experiments. We emphasize the importance of next to leading order (NLO) and kinematical twist 3 and 4 contributions to interpret data in the JLab kinematics. We deduce a first tomographic image of quarks and gluons in the helium-4 nucleus.
• Quark and gluon tomography of the helium-4 nucleus
  
  • Martínez-Fernández V.
  • Pire B.
  • Sznajder P.
  • Wagner J.
  Physical Review Letters, American Physical Society, 2026, 137, pp.111905. QCD collinear factorization allows coherent hard exclusive reactions to reveal the quark-gluon structure of light nuclei, enabling their 3D tomography. We study elastic form factors and deeply virtual Compton scattering on a helium-4 target, achieving theoretical precision unprecedented even in proton studies. Constraining generalized parton distributions at next-to-leading order in $α_s$, incorporating kinematic twist corrections, and using full evolution equations, we provide the first tomography of a light nucleus, revealing distinct transverse spatial distributions of quarks and gluons. (10.1103/634s-zcy6)
  DOI : 10.1103/634s-zcy6
• Coherent deeply virtual Compton scattering on helium-4 beyond leading power
  
  • Martínez-Fernández Víctor
  • Pire B.
  • Wagner J.
  • Sznajder P.
  Physical Review C, American Physical Society, 2026, 114, pp.0325203. Coherent hard exclusive reactions on light nuclei provide access to their quark and gluon structure and enable three-dimensional tomography of these complex systems. We study deeply virtual Compton scattering on a helium-4 target, including both kinematic twist-3 and twist-4 corrections, as well as next-to-leading-order corrections to the twist-2 amplitude in the strong coupling α_s. We show that these contributions are crucial for achieving a precise description of the data and, as a result, obtain the first tomographic image of the helium-4 nucleus at the quark-gluon level. (10.1103/h7kn-ql7j)
  DOI : 10.1103/h7kn-ql7j
• Carroll-Cotton Tensors and Gravitational Radiation at Null Infinity
  
  • Fiorucci Adrien
  • Pekar Simon
  • Petropoulos P. Marios
  • Vilatte Matthieu
  , 2026. We provide a first-principles definition of Cotton tensors on conformal Carroll geometries by gauging the conformal Carroll algebra. On the mathematical side, this analysis yields a conformally covariant object designed to quantify deviations from conformal flatness in Carrollian geometries. On the physical side, it offers a powerful geometric tool to describe gravitational radiative degrees of freedom at the conformal boundary of four-dimensional asymptotically flat spacetimes. Unlike the Bondi news, whose fully-covariant definition requires amendment by supplementary data that we identify with the Geroch tensor, the Carroll-Cotton tensors offer the natural geometric objects to quantify deviations from stationarity due to the emission of gravitational waves.
• Before the Bang: Wormholes at the dawn of the universe
  
  • Betzios Panos
  • Ghiringhelli Paul
  • Gialamas Ioannis
  • Papadoulaki Olga
  International Journal of Modern Physics D, World Scientific Publishing, 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 wave functions, 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 landscape 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
• Gluonic nucleon energy correlators and fracture functions for Color Glass Condensate
  
  • Mäntysaari Heikki
  • Shi Yu
  • Tawabutr Yossathorn
  • Tong Xuan-Bo
  , 2026. Nucleon energy correlators (NECs) and fracture functions provide novel tools for probing nucleon and nuclear structure at small $x$ through measurements in the target fragmentation region (TFR) of deep inelastic scattering (DIS). We investigate gluonic NECs and fracture functions using the Color Glass Condensate effective theory at eikonal accuracy. We find that only the unpolarized and linearly polarized gluon components in an unpolarized target are nonvanishing at this order, and that both are determined by the adjoint dipole $S$-matrix. Furthermore, we show that the linearly polarized gluonic NEC $h_{1}^{t,g}$ generates a characteristic $\cos 2ϕ$ azimuthal asymmetry in the DIS energy pattern in the TFR. Unlike analogous observables in the current fragmentation region, this asymmetry is governed by the ratio of the linearly polarized gluon NEC $h_{1}^{t,g}$ to the unpolarized quark NEC $f_{1}^{q}$, making it particularly sensitive to the saturation scale. Our numerical analysis shows that this asymmetry exhibits substantial nuclear suppression, providing a novel window into the onset of gluon saturation at the future Electron-Ion Collider.
• Spin response of a magnetic monopole and quantum Hall response in topological lattice models through local invariants and light
  
  • Le Hur Karyn
  • Baldanza Andrea
  Comptes Rendus. Physique, Académie des sciences (Paris), 2026, 27, pp.323 - 351. Here, we elaborate on and develop the geometrical approach introduced in Le Hur, Phys. Rep. 1104 (2025) between the magnetic monopole created from a radial field, quantum physics and topological lattice models through quantum phase transitions. We introduce an effective magnetic moment for a monopole when applying an additional source field along z-direction which also mediates the quantum phase transition. We present its relation with the transverse pumped quantum Hall current. The magnetic susceptibility can be introduced as a measure of the topological invariant i.e. it remains quantized within the topological phase until the transition. We show the relation with two-dimensional topological lattice models such as a honeycomb Haldane model in real space. We develop the theory and present a numerical analysis between local invariants in momentum space introduced from Dirac points, a real space correspondence and the responses to circularly polarized light. We develop the formalism for coupled-planes materials including the possibility of quantum spin Hall effect and address a relation between the Ramanujan infinite alternating series and an interface in real space with a topological number one-half. (10.5802/crphys.287)
  DOI : 10.5802/crphys.287
• Finite Formation Time Antenna Radiation: Color Spectators Break Single-Emitter BDMPS-Z
  
  • Domínguez Fabio
  • Guerrero-Rodríguez Pablo
  • Salgado Carlos A
  , 2026. We compute the direct contribution to the squared matrix element for the in-medium soft gluon emission off a color-singlet quark-antiquark pair. To do this, we incorporate medium interactions that take place during the finite formation time of the antenna, thereby accounting for a largely neglected source of modifications with respect to the vacuum baseline. As a consequence, non-trivial correlations with the spectator (i.e. non-emitting) leg of the antenna emerge, greatly increasing the complexity of the result even at leading-$N_c$ order. The observed modifications entail a significant departure from the limit of instantaneous antenna formation, where the calculation effectively reduces to the well-known BDMPS-Z spectrum.
• Dressed States Call for Logarithmic Asymptotic Symmetries
  
  • Bosma Jorrit
  • Mann Jeremy A
  • Marteau Charles
  • Oblak Blagoje
  • Petropoulos Marios
  , 2026. Inspired by Wigner's classification of elementary particles as irreducible unitary representations of a spacetime symmetry group, we ask what group can give rise in this way to the quantum states of a particle dressed with clouds of infrared gauge bosons. We show that the answer is given by standard asymptotic symmetries (such as BMS in the gravitational case), supplemented by the logarithmic symmetries identified in arXiv:2305.05436. A corollary is the factorization of the Hilbert space of a dressed particle as a tensor product of the space of `naked' one-particle states with a Hilbert space of soft gauge bosons. The latter cannot be obtained without logarithmic transformations, which are ultimately responsible for the presence of a crucial Heisenberg central extension.
• Quantum Mechanics on Lie Groups: II. Path Integrals
  
  • Beauvillain Mathieu
  • Oblak Blagoje
  • Petropoulos Marios
  , 2026. We continue our study of quantum dynamics on a Lie group $G$, initiated in arXiv:2512.19840, by building the path integral that governs transition amplitudes in the Hilbert space $L^2(G)$. This relies on the proper handling of both a noncommutative momentum space and the presence of compact directions in $G$. We show that compactness can be handled through a sum over winding numbers in maximal tori of $G$, generalizing the similar sum commonly encountered for path integrals on a circle. As applications, we compute semiclassical approximations of propagators and partition functions of Euler-Arnold systems, up to (and including) two-loop order.
• Mitigation of Cross Beam Energy Transfer with enhanced phase depth capacities on Mega-Joule lasers
  
  • Meynard Godefroy
  • Riazuelo Gilles
  • Penninckx Denis
  • Hüller Stefan
  , 2026. Energy exchange between crossed laser beams (CBET) is investigated in presence of Smoothing by Spectral Dispersion (SSD) for the laser bandwidth features available at the Laser MégaJoule (LMJ) facility in France. The study relies on results from numerical simulations with the codes HARMONY and PARAX for the reference configuration of two crossing laser beams which are subject to either spatial or spatially-temporal smoothing. We compare the net energy transfer, the angular distribution as well as the spectral bandwidth of the transmitted light between beams smoothed merely via Random Phase Plates (RPP) or via SSD for two types of interaction; namely (i) when both beams are mutually shifted in their frequency by values close to the frequency of the acoustic wave excited by the overlap of both beams, or (ii) when almost sonic plasma flow is present underneath the Bragg-type density perturbations excited by both beams. Both the flow velocity and the frequency shift between beams are varied in simulations to examine the essential parameter space at and around resonant CBET interaction. We find that close to resonance, and in particular for focusing f-numbers f# < 8 the net transfer provoked by CBET is smaller for frequency shift ∆ω with respect to equivalence with flow. The phase modulation of SSD is defined via exp(iδ sin 2πνmt), with the modulation frequency of νm being 14.25GHz, and δ , the modulation depth which can be chosen between 0 (no SSD) and 15 on LMJ. Our simulation results show such that at high δ -values CBET is considerably mitigated at and around resonance with, however, a broad spectral window for coupling, while for lower modulation depth values (δ < 7.5) the mitigation remains limited.
• Free Majorana fermions with superconducting quantum wires and a magnetic impurity
  
  • Le Hur Karyn
  Comptes Rendus. Physique, Académie des sciences (Paris), 2026, 27, pp.307 - 322. Through the two-channel Kondo model, I address a magnetic spin-1/2 impurity interacting with a bound state of spin origin at the edge in a Luther-Emery liquid showing a spin gap in the bulk. The system presents two zero-energy Majorana fermions of magnetic origin, one on the impurity site and one at the edge. I derive the wavefunction at the edge for the produced zero-energy Majorana fermion bound state within the same formalism as topological interfaces. I present alternative versions of the quantum field theory revealing the specific pairing of the Majorana fermions in the bulk. I address local physical responses. I develop the idea that this model can be realized with a magnetic impurity bridging the gap between two swave superconducting wires. I show the protection of the zero-energy Majorana fermions that will be referred to as free Majorana fermions. (10.5802/crphys.284)
  DOI : 10.5802/crphys.284
• Conformal Renormalisation of 8D Einstein Gravity
  
  • Anastasiou Giorgos
  • Araya Ignacio J
  • Boulanger Nicolas
  • Olea Rodrigo
  • Rovere Davide
  , 2026. We show that Holographic Renormalisation (HR) in eight dimensions is encoded in the unique conformal gravity theory that admits an Einstein sector with constant negative curvature. We explicitly relate HR to Topological Regularisation (TR), where the latter prescribes to add the Euler term to the Einstein-Hilbert Lagrangian density, with a precise coefficient so as to ensure that the resulting density is polynomial in the anti de Sitter (AdS) curvature. The polynomial is still asymptotically divergent. We find that the aforementioned, unique conformal gravity action in 8D, reproduces the polynomial, together with extra boundary terms that cancel the divergent terms in the action. We conjecture that, in arbitrary even dimension, HR is equivalent to conformally completing the Einstein-Hilbert action with negative cosmological constant, plus the Euler term with fixed coupling prescribed by TR.
• Investigating Spatio-Temporal Dynamics and Self-Steepening in Multi-Pass Cells
  
  • Couairon Arnaud
  • Fsaifes Ihsan
  • Chanteloup Jean-Christophe
  • Houard Aurélien
  , 2026, pp.35. Driven by the need for robust, high-energy pulse compression methods that circumvent bulk damage limitations, multi-pass cells (MPCs) have emerged as a premier technology for spectral broadening, yet the complex coupling between spatial self-focusing and temporal self-steepening remains under-explored [1-3]. In this work, I will present a comprehensive numerical study using a full radial 3D propagation code to evaluate nonlinear pulse evolution in gas-filled MPCs with self-steepening enabled. I will present a systematic comparison of a spatially resolved model against traditional 1D approximations, illustrating the breakdown of 1D theory under intense spatial-temporal clustering and localized self-focusing. Furthermore, I will analyze the impact of input peak power, the accumulated nonlinear phase across consecutive roundtrips, the cell geometry (specifically sweeping the cavity length to mirror curvature ratio (L/R) from near-confocal to near-concentric configurations), and the gas pressure on the resulting blue-shifted spectral asymmetry and post-compression pulse quality. These results show how spatial mode dynamics directly alter temporal shock formation, providing concrete design rules to optimize spectral broadening and minimize uncompressible phase pedestals in next-generation MPC architectures.