Publications

2026

• Time-dependent Neural Galerkin Method for Quantum Dynamics
  
  • Sinibaldi Alessandro
  • Hendry Douglas
  • Vicentini Filippo
  • Carleo Giuseppe
  Physical Review Letters, American Physical Society, 2026, 136 (12), pp.120402. We introduce a classical computational method for quantum dynamics that relies on a global-in-time variational principle. Unlike conventional time-stepping approaches, our scheme computes the entire state trajectory over a finite time window by minimizing a loss function that enforces the Schrödinger's equation. The variational state is parametrized with a Galerkin-inspired ansatz based on a time-dependent linear combination of time-independent Neural Quantum States. This structure is particularly well-suited for exploring long-time dynamics and enables bounding the error with the exact evolution via the global loss function. We showcase the method by simulating global quantum quenches in the paradigmatic Transverse-Field Ising model in both 1D and 2D, uncovering signatures of ergodicity breaking and absence of thermalization in two dimensions. Overall, our method is competitive compared to state-of-the-art time-dependent variational approaches, while unlocking previously inaccessible dynamical regimes of strongly interacting quantum systems. (10.1103/kqvx-dl54)
  DOI : 10.1103/kqvx-dl54
• 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
• Hyperbolic form factors for Yukawa interactions, and applications to the Earth
  
  • Fayet Pierre
  European Physical Journal C: Particles and Fields, Springer Verlag (Germany), 2026, 86 (9), pp.1125. We define the hyperbolic form factor of a density distribution as its bilateral Laplace transform, related by duality or analytic continuation to its form factor. For a sphere it is given by $Φ(x = kR) =\langle \cosh \vec k.\vec r\rangle=\langle\sinh kr /kr\rangle $, expanded as $\sum \frac{x^{2n}}{(2n+1)!} \frac{\langle r^{2n}\rangle}{R^{2n}} $, and similarly for the form factor $ \langle \sin kr/kr\rangle$. It is also obtained from the bilateral Laplace transform of $2πr\,ρ(|r|)$, and enters in the determination of the outside Yukawa potential induced by a new charge for a mediator of mass $m=k=1/λ$. $Φ(x)$ may be expressed as $\frac{3}{x^3}\,(x \cosh x - \sinh x)\ \barρ(x)/ρ_0$, where $\barρ(x)$ is an effective density decreasing, for $dρ/dr<0$, from the average $ρ_0$ at small $x$, down to $ρ(R)$. An inversion formula allows one to recover $ρ(r)$ from an analytic continuation of $Φ(x)$, as $ρ(r) =ρ_0\,(2R/3πr)\intΦ(ix) \sin (x\frac{r}{R})\,x\,dx$. $Φ(x)$ for the Earth is essential to determine limits on a new force, as tested by MICROSCOPE, depending on the density distribution within the Earth. Quite remarkably, much simplified density profiles, such as $ρ= ρ_0\ 2R/3r $ or $ρ= ρ_0\, (\frac54-\frac{r}{R}+ \frac{R}{3r})$, provide analytic expressions of $Φ(x)$ and $\barρ(x)$ giving almost the same values as in a 5-shell model. $\,Φ(x)=(\sinh\frac{x}{2}/\frac{x}{2})^2$ is valid to within $\simeq 1\,\%$ up to $x=4$. $\,Φ(x)= [7x^2\cosh x-24\cosh x+9x\sinh x -4x^2+24]/(4x^4)$ is valid to within 1 % for $λ> $ 100 km (or $m< 2\times 10^{-12}$ eV/$c^2$). For $m=10^{-12}$ eV/$c^2$ the coupling limits are increased by 34 as compared to a massless mediator, to $|g_{B-L}|< 3.6 \times 10^{-24} $ and $|g_B|<2.6\times 10^{-23}$ for a spin-1 mediator, with slightly different limits in the spin-0 case. (10.1140/epjc/s10052-026-15933-4)
  DOI : 10.1140/epjc/s10052-026-15933-4
• 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
• 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
• Uniqueness of D=8 minimal supergravity with two vector multiplets
  
  • Bossard Guillaume
  • Lao Bingxin
  • Minasian Ruben
  JHEP, 2026, 09, pp.192. There exist only four known string theories with minimal supersymmetry in eight dimensions, whose low energy effective descriptions are given by minimal supergravity coupled to $l=18$, $10$, or $2$ vector multiplets. It has been argued that these numbers are uniquely fixed by consistency conditions of the effective theory. In this work, we investigate the protected couplings of minimal supergravity coupled to two vector multiplets under the assumption that the theory admits a duality symmetry of the form $Γ_0(N)\times Γ_0(N)\subset {\rm SL}(2,\mathbb{Z}) \times {\rm SL}(2,\mathbb{Z})$ for some positive integer $N$. We show that consistency with anomaly cancellation, higher-dimensional uplifts, and gauge enhancement loci strongly constrains the allowed couplings and isolates a unique consistent theory in the BPS sector. In particular, we find that the Bianchi identity for the three-form flux cannot have gravitational contributions. (10.1007/JHEP09(2026)192)
  DOI : 10.1007/JHEP09(2026)192
• 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
• 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
• Extracting light-cone wave functions from covariant amplitudes: a detailed study in scalar field theory
  
  • Munier Stéphane
  Physical Review D, American Physical Society, 2026, 114 (3), pp.036015. We propose a conjectured formula that systematically maps covariant off-shell amplitudes to light-cone wave functions in scalar field theory. Through an explicit comparison at one-loop accuracy, we establish its equivalence to the light-cone perturbation theory series, thereby validating the conjecture at this order. Applying this formula, we efficiently re-derive wave functions from known covariant amplitudes, bypassing both the conceptual complexities of light-cone quantization and the technical challenges of perturbative calculations in this framework. In addition to simplifying computations, this approach opens new avenues for applications in gauge theories and deeper explorations of the fundamental equivalence between covariant and light-cone quantization. (10.1103/63qq-rx6g)
  DOI : 10.1103/63qq-rx6g
• Physique de la matière condensée
  
  • Georges Antoine
  L'Annuaire du Collège de France. Résumés des cours et travaux, Collège de France, 2026 (122), pp.97-102. (10.4000/15e0h)
  DOI : 10.4000/15e0h
• Quark orbital angular momentum from chiral symmetry breaking in QCD
  
  • Kim June-Young
  • Won Ho-Yeon
  • Weiss Christian
  Physics Letters B, Elsevier, 2026, 882, pp.140980. The flavor-nonsinglet (<math altimg="si13.svg"><mrow><mi>u</mi><mo linebreak="goodbreak">−</mo><mi>d</mi></mrow></math>) quark angular momentum (AM) in the proton is computed based on the effective spin-flavor dynamics emerging from chiral symmetry breaking by QCD instantons. The QCD AM operators are converted to effective spin-flavor operators expressing instanton-induced chiral interactions. A large negative orbital AM <math altimg="si5.svg"><msub><mi>L</mi><mrow><mi>u</mi><mo>−</mo><mi>d</mi></mrow></msub></math> arises from the interactions of the quarks with the chiral mean field in the proton in the large-Nc limit. It cancels part of the large positive spin AM <math altimg="si4.svg"><msub><mi>S</mi><mrow><mi>u</mi><mo>−</mo><mi>d</mi></mrow></msub></math> and reduces the total AM <math altimg="si14.svg"><mrow><msub><mi>J</mi><mrow><mi>u</mi><mo>−</mo><mi>d</mi></mrow></msub><mo linebreak="goodbreak">=</mo><msub><mi>S</mi><mrow><mi>u</mi><mo>−</mo><mi>d</mi></mrow></msub><mo linebreak="goodbreak">+</mo><msub><mi>L</mi><mrow><mi>u</mi><mo>−</mo><mi>d</mi></mrow></msub></mrow></math>, in agreement with lattice QCD calculations. (10.1016/j.physletb.2026.140980)
  DOI : 10.1016/j.physletb.2026.140980
• Walsh series and Pauli decompositions: representing functions on a quantum system
  
  • Ayral Thomas
  • Boudin Laurent
  • Maday Yvon
  • Serret Michel Fabrice
  , 2026. The Pauli decomposition of quantum operators is of prime importance to many quantum algorithms, but computing it numerically often incurs an exponential cost in the number of qubits. In this work, we extend the connection between Pauli decompositions of operators on qubit-based quantum systems and the Walsh L2-basis defined from dyadic rationals. We prove that diagonal operators can be decomposed using the Walsh interpolant of the associated function, and introduce a new estimation method based on truncated Walsh series with exponential convergence in the number of qubits. We also derive explicit Walsh expansions for Fourier basis functions, which, combined with known results for polynomials, enable analytical Pauli decompositions for functions expressed as linear combinations of both. Finally, we apply these techniques to Gross-Pitaevskii energy operators, obtaining explicit Pauli decompositions including the nonlinear interaction term.
• Heavy-Heavy-Light Asymptotics from Thermal Correlators
  
  • Burić Ilija
  • Mangialardi Francesco
  • Russo Francesco
  • Schomerus Volker
  • Vichi Alessandro
  Journal of High Energy Physics, Springer, 2026, 04, pp.027. We revisit the calculation of spectral densities and heavy-heavy-light (HHL) operator product expansion (OPE) coefficients in three-dimensional conformal field theories using thermal one-point functions on $S^1 \times S^2$. A central element of our analysis is a new inversion formula for one-point functions which is derived via Casimir differential equations. We develop systematic expansions of the spectral density and HHL OPE coefficients in the regime of large $Δ_H$. We validate our analytic tools by comparing the results with the partial wave expansions of thermal one-point functions in free field theories. The algorithms developed for these expansions make full use of Casimir recursion relations, thereby extending their applicability into the heavy exchange regime. In the end, we observe excellent agreement with our analytic predictions and an improvement of up to three orders of magnitude compared to all previous leading order estimates of the CFT data even for moderate values of $Δ_H$. (10.1007/JHEP04(2026)027)
  DOI : 10.1007/JHEP04(2026)027
• Fermion parity switching in a short Kitaev chain coupled to a photonic cavity
  
  • Fernandez Becerra Victor
  • Dmytruk Olesia
  Physical Review B, American Physical Society, 2026, 113 (16), pp.165410. We study a finite-length Kitaev chain coupled to a single mode photonic cavity. The topological phase of the finite-length Kitaev chain is characterized by the presence of fermion parity switching points that correspond to the degeneracy between even and odd parity ground states. Using exact diagonalization, we compute the many-body energy spectrum of the electron-photon Hamiltonian and we find that the ground state in the topological phase of the Kitaev chain is only weakly affected by the cavity coupling. This is in contrast with the excited states showing strong dependence on the cavity frequency. We find that the photon number and the photonic field quadratures peak at values of the chemical potential corresponding to parity switching points revealing a property of the finite-length Kitaev chain in the topological phase. This later finding suggests that quantum optics experiments could be used to detect topological features of the Kitaev chain embedded into a photonic cavity. Moreover, calculations of photonic quadratures reveal squeezed states that are both captured by the exact diagonalization technique and mean-field decoupling. However, the mean-field approach fails to correctly capture the photonic probability in the odd photonic states. (10.1103/hszk-ymf3)
  DOI : 10.1103/hszk-ymf3
• The Lee-Yang model and its generalizations through the lens of long-range deformations
  
  • Eustachon Fanny
  EPL, 2026, 156 (4), pp.40004. In two dimensions, the non-unitary class of conformal minimal models, $\mathcal{M}(2,2m+1)$, has been recently conjectured to arise as renormalization-group fixed points of scalar field theories with complex $iφ^{2m-1}$ interaction, $m\in \mathbb{N}$, $m\ge2$. We test a variation of this conjecture through the perturbative study of two separate long-range constructions based on respectively the minimal model and its potential Landau-Ginzburg formalism. For $m>2$, inconsistencies are found when subsequently relating both constructions. In contrast, the long-range Lee-Yang model, the $m=2$ case, is shown to be analogue to the long-range Ising model. (10.1209/0295-5075/ae9daf)
  DOI : 10.1209/0295-5075/ae9daf
• Ab initio spin Hamiltonians and magnetism of Ce and Yb triangular-lattice compounds
  
  • Pourovskii Leonid
  • Soares Rafael
  • Wietek Alexander
  Physical Review B, American Physical Society, 2026, 113 (6), pp.L060401. We calculate the crystal-field splitting, ground-state Kramers doublet and intersite exchange interactions within the ground-state doublet manifold using an ab initio Hubbard-I based approach for a representative set of Ce and Yb triangular-lattice compounds. These include the putative quantum spin liquids (QSL) RbCeO₂ and YbZn₂GaO₅ and the antiferromagnets KCeO₂ and KCeS₂. The calculated nearest-neighbor (NN) couplings are antiferromagnetic and exhibit noticeable anisotropy. The next-nearest-neighbor (NNN) couplings are ferromagnetic in the Ce systems and dominated by classical dipole-dipole interactions in the Yb case. Solving the resulting effective spin-1/2 models by exact diagonalization up to N = 36 sites, we predict ordered magnetic ground states for all systems, including the two QSL candidates. We explore the phase space of an anisotropic NN + isotropic NNN triangular-lattice model finding that a significant antiferromagnetic NNN coupling is required to stabilize QSL phases, while the NN exchange anisotropy is detrimental to them. Our findings highlight a possibly important role of deviations from the perfect triangular model -like atomic disorder -in real triangular-lattice materials. (10.1103/95x5-3fnn)
  DOI : 10.1103/95x5-3fnn
• Hydrodynamics in the Carrollian regime
  
  • Kolekar Kedar S
  • Mandal Taniya
  • Shukla Ashish
  • Soni Pushkar
  Int.J.Mod.Phys.A, 2026, 41 (02), pp.2650016. Carroll hydrodynamics arises in the $c\to 0$ limit of relativistic hydrodynamics. Instances of its relevance include the Bjorken and Gubser flow models of heavy-ion collisions, where the ultrarelativistic nature of the flow makes the physics effectively Carrollian. In this paper, we explore the structure of hydrodynamics in what can be termed as the Carrollian regime, where instead of keeping only the leading terms in the $c\to 0$ limit of relativistic hydrodynamics, we perform a small-$c$ expansion and retain the subleading terms as well. We do so both for perfect fluids as well as viscous fluids incorporating first order derivative corrections. As apposite applications of the formalism, we utilize the subleading terms to compute modifications to the Bjorken and Gubser flow equations which bring in, in particular, dependence on rapidity. (10.1142/S0217751X26500168)
  DOI : 10.1142/S0217751X26500168
• Holographic shear correlators at low temperatures, and quantum $η/s$
  
  • Kanargias Alexandros
  • Kiritsis Elias
  • Murthy Sameer
  • Papadoulaki Olga
  • Porfyriadis Achilleas P
  Journal of High Energy Physics, Springer, 2026, 07, pp.149. The strongly-coupled 3-dimensional theory, holographically dual to black branes at fixed chemical potential $\muext$ and temperature $T \ll μ$ is considered in AdS$_4$ Einstein-Maxwell theory. The retarded Green's functions at frequency $ω$ is calculated using holography in the regime $ω, T \ll \muext$ but otherwise arbitrary. When the transverse space has finite volume, there is a non-zero energy scale $E_\text{gap}$, scaling as $1/μ$ for large $μ$, below which quantum-gravitational corrections due to the fluctuations of the nearly-gapless Schwarzian modes become important. Such corrections to the retarded Green's function are calculated at different relative values of $ω$, $T$, and $E_\text{gap}$. The $ω\to 0$ limit is used to define the shear viscosity $η$. As the temperature is lowered below $μ$, quantum corrections are found to increase the value of $η$ with respect to its semiclassical value. The quantum-corrected result for $η$ diverges as $\sqrt{E_\text{gap}/T}$ at $T \ll E_\text{gap}$, in accord with corresponding results for the absorption cross section. The quantum result for the ratio $η/s$, where $s$ is the entropy density, dips below the semiclassical limit of $1/4π$ when $E_\text{gap} \ll T \ll μ$, then turns back to increase towards lower temperatures, and finally diverges at temperatures much below $E_\text{gap}$. (10.1007/JHEP07(2026)149)
  DOI : 10.1007/JHEP07(2026)149
• Simple Scaling Laws for Energy Correlators in Nuclear Matter
  
  • Andres Carlota
  • Dominguez Fabio
  • Holguin Jack
  • Marquet Cyrille
  • Moult Ian
  Physical Review Letters, American Physical Society, 2026, 136 (12), pp.122301. Collider experiments involving nuclei provide a direct means of studying exotic states of nuclear matter. Recent measurements of energy correlators in both proton-nucleus (p-A) and nucleus-nucleus (A-A) collisions reveal sizable modifications, attributable to nuclear effects, compared to proton-proton (p-p) collisions. Energy correlators, and their associated light-ray operator product expansion (OPE), allow scaling behaviors of the measured spectrum to be directly mapped to properties of the underlying quantum field theory. Here, we demonstrate for the first time how this mapping occurs in nuclear collisions, and highlight how the light-ray OPE characterizes leading nuclear effects. We show that the leading modification to the energy correlator distribution is characterized by an enhancement of the expectation value of twist-4 light-ray operators, resulting in a scaling for the ratio of the two-point correlator in nuclear matter to that in vacuum of $\sim 1+a\theta^2$ up to quantum corrections. We verify that this leading twist-4 correction accurately describes recent A-A and p-A data, and is thus sufficient to capture the scaling behavior within the angular range measured for jet radii used in nuclear experiments. Our light-ray OPE based approach lays the groundwork for a rigorous characterization of nuclear modification to energy correlator observables. (10.1103/sw7p-7jbp)
  DOI : 10.1103/sw7p-7jbp
• Complex logistic equation for universal energy evolution in hadronic elastic scattering
  
  • Kohara Anderson Kendi
  Physical Review D, American Physical Society, 2026, 113 (11), pp.116041. We introduce a universal evolution equation for elastic scattering of hadrons, derived from Reggeon field theory and solved in closed analytical form. The equation has a complex logistic structure and evolves initial amplitude profiles from existing models at a fixed energy, reproducing both differential cross sections and integrated quantities over a broad energy range. It admits a unique solution for each initial condition and rigorously satisfies unitarity, the Froissart–Martin bound, and dispersion relations. The dynamics are governed by two physically meaningful parameters: the effective Pomeron mass <math display="inline"><msub><mi>ε</mi><mi mathvariant="script">P</mi></msub></math> and the nonlinear coupling <math display="inline"><mrow><mi>λ</mi></mrow></math>, both fitted at a single energy. By decoupling the nonperturbative input from the universal energy evolution, the framework enables model-independent extrapolations and provides a minimal predictive alternative to eikonal resummation. Moreover, the structure of the equation—featuring rapidity evolution, saturation, and impact-parameter dependence—shares qualitative features with nonlinear QCD equations at small-<math display="inline"><mi>x</mi></math>, such as Balitsky-Kovchegov and Jalilian-Marian, Iancu, McLerran, Weigert, Leonidov, and Kovner, suggesting a possible bridge between Regge-based and QCD-based approaches to high-energy scattering. (10.1103/xz23-bqg9)
  DOI : 10.1103/xz23-bqg9