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Physics

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Thursday 18 June

Nuclear Experiment

Modification of jet-energy flow in heavy-ion collisions

ALICE Collaboration

The ALICE Collaboration presents the first measurements of the jet-energy flow ($\Delta p_{\rm T}$) observable in proton-proton and heavy-ion collisions. Jets are excellent probes for the quark$-$gluon plasma, a deconfined state of matter produced in heavy-ion collisions. The jet-energy flow observable characterizes the radial distribution of energy from the jet axis in an infrared and collinear-safe way and is sensitive to medium-induced parton-shower modifications. Inclusive charged jets are measured in Pb$-$Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV for the transverse-momentum interval 60$-$80 GeV/$c$. For pp collisions at $\sqrt{s}=13$ TeV, measurements include the 40$-$60 and 60$-$80 GeV/$c$ intervals, where the latter serves as the reference for investigating medium-induced modifications. Results show that most parton energy is concentrated in the jet core, with a clear suppression of energy flow in heavy-ion collisions at larger radii (significance 3.5$-$4.5$\sigma$) indicating a narrowing of the energy flow. While all models – PYTHIA 8, HERWIG, JEWEL, and JETSCAPE – reproduce the pp results with only small deviations in the tails, the relative modification in Pb$-$Pb collisions is well described by JEWEL without recoil. Conversely, JEWEL with recoil (medium response) and JETSCAPE show significant deviations, exhibiting increasing or more constant trends with radius that are disfavored by the data.
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Adaptation and Self-Organizing Systems

Nodal Braess's Paradox and Inertia Destabilization with Dynamic Node and Line Failures in Power Grids

Nubius Brandner, Frank Hellmann, Hans Würfel et al. (+3 more)

Large-scale power outages are typically caused by cascading failures. These unfold dynamically through complex interactions between network dynamics and individual component failures. In contrast, the study of cascading failures in physics has focused on analyzing line overloads in the quasi-static regime. We introduce a new model that integrates the dynamics of node and line failures with a paradigmatic oscillator model for power grid synchronization. This enables us to investigate the collective cascading behavior of coupled failures for the first time. We study the impact of nodal robustness, the ability of nodes to tolerate transient disturbances, and inertia, the ability of nodes to resist frequency deviations, on cascade sizes. We discover two novel mechanisms driving system fragility: i) While low inertia is widely considered a major challenge for power grids, we find that high inertia can amplify cascade sizes unless accompanied by appropriate adjustments of other dynamical properties. ii) Further, we find that an increase in the robustness of individual nodes can paradoxically lead to larger cascades. This latter phenomenon constitutes a novel type of Braess's paradox. Understanding such counterintuitive collective effects may become central for achieving resilient future power grids.
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All authors Nubius Brandner, Frank Hellmann, Hans Würfel, Jürgen Kurths, Anton Plietzsch, Anna Büttner

High Energy Physics (Phenomenology)

Non-standard decays of vector-like top partners in a $2$-Higgs doublet model at the HL-LHC

Tanumoy Mandal, Stefano Moretti and Rachit Sharma

Extensions of the Standard Model featuring both an enlarged scalar sector and vector-like fermions arise naturally in a wide class of well-motivated theoretical frameworks. In such scenarios, vector-like Quarks (VLQs) can exhibit non-standard decay modes involving additional Higgs states, giving rise to distinctive collider signatures that remain largely unexplored by existing experimental searches. We investigate the prospects of probing this possibility at the high-luminosity Large Hadron Collider (HL-LHC) through the decay of vector-like top partner ($T$) to charged Higgs ($H^{\pm}$) followed by the decay, $H^\pm\to\tau\nu$, producing a final state containing two tau leptons, two $b$-jets, and missing transverse energy. A model-independent collider analysis is performed using global kinematic observables constructed from visible objects and the missing transverse momentum vector to suppress the dominant backgrounds. Polarization-sensitive observables built from the hadronic $\tau$ decay products are also examined as complementary probes of the spin-$0$ origin of the $\tau$ leptons. The expected discovery sensitivity is evaluated using the Asimov significance for an integrated luminosity of $3$ ab$^{-1}$ at $\sqrt{s}=14$ TeV. Our results demonstrate that the $2\tau\:+\:2b\:+$ missing $E_T$ channel provides a promising and largely orthogonal avenue to search for non-standard VLQ decays in extended Higgs sectors, with discovery-level sensitivity achievable for VLQ masses up to approximately $1.9$ TeV.
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Atmospheric and Oceanic Physics

Enhanced Gulf Stream Path Variability Under Intensified Stratification

Lennard Miller, Antoine Venaille, Stephane Popinet et al. (+1 more)

Increased upper-ocean stratification is an unavoidable consequence of global warming and will strongly impact the structure of ocean currents. Using a high-resolution ocean model, we show that intensification of stratification leads to the loss of coherence of the Gulf Stream Extension, replacing its steady eastward path with vigorous, chaotic meanders. This regime shift persists independently of changes in the Atlantic Meridional Overturning Circulation and surface wind forcing. Enhanced meandering under intensified stratification also proves to be a robust feature across both idealized and realistic ocean models that resolve mesoscale eddies, but is not captured by coarse-resolution models that parameterize eddies. The presented findings therefore highlight the need for improved representations of oceanic turbulence in climate projections.
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All authors Lennard Miller, Antoine Venaille, Stephane Popinet, Bruno Deremble

Soft Condensed Matter

Constraint-Limited Tube Orientation of Entangled Polymers in Oscillatory Shear Deformation

Dario Nichetti and Alessio Zaccone

We develop a molecularly motivated description of the nonlinear index (NLI) in oscillatory shear deformation of entangled polymers. The central assumption is that the shear component of the tube-orientation tensor cannot grow without bound. Convective constraint release (CCR), chain stretch, and tube dilation progressively reduce the number and lifetime of orientational constraints, but the maximum shear alignment of a tube segment is geometrically limited by $S_{xy}\leq 1/2$. This motivates a constraint-limited orientation closure in which the NLI first grows approximately with strain amplitude and then approaches the limiting value $\mathrm{NLI}_{\max}=3$ asymptotically rather than through an artificial cutoff. The same framework yields a molecular expression for the characteristic half-saturation strain $\gamma_s$, defined by $\mathrm{NLI}(\gamma_s)=3/2$, in terms of the entanglement number, oscillation frequency, and a critical number of remaining orientational constraints. We further derive architecture-dependent expressions for the nonlinear onset strain $\gamma_c$ for linear, sparsely long-chain-branched, and more regularly branched polymers. The resulting framework provides a compact bridge between Fourier harmonic analysis, CCR-based tube dynamics, and the progressive loss of orientational memory in highly deformed entangled polymer liquids.
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General Relativity and Quantum Cosmology

On the Plebanski Formulation with Energy Momentum

Jack C. M. Hughes, Joudy F. Jamal Beek and Fedor V. Kusmartsev

In Plebanski's formulation the coupling of matter is less direct than in the metric formulation since the energy-momentum tensor $T_{\mu\nu}$ is symmetric, while the Plebanski variables are naturally valued in the self-dual/anti-self-dual Hodge decomposition of 2-forms. An explicit construction of the Plebanski matter source $T^i$ is obtained by lifting the trace-free energy-momentum tensor $\hat T_{\mu\nu}$ into the $(1,1)$ component of the algebraic curvature space using the Kulkarni-Nomizu product, and then extracting its chiral components. This construction reproduces the definition for $T^i$ in terms of the self-dual basis $\Sigma^i$ and $\hat T_{\mu\nu}$ introduced by Krasnov. We also verify that the matter-coupled chiral field equations imply the usual conservation law $\nabla_{\mu}T^{\mu \nu}=0$ through the chiral Bianchi identity $d^A F^i=0$. As an application, the construction is applied to a spherically symmetric electromagnetic stress-energy tensor, where the anti-self-dual part of the matter-coupled Plebanski field equations yields the Reissner-Nordström-de Sitter solution. The result gives a systematic prescription for translating metric matter sources into the anti-self-dual source terms required by the Plebanski field equations.
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Soft Condensed Matter

Electrostatic effects in nano-reactor-confined charge regulated macroions

Manit Klawtanong, Petch Khunpetch, Huaqiong Li et al. (+1 more)

We formulate a thermodynamic model of a nano-reactor containing charge-regulated macroions within an electrolyte-permeable enclosure. The model is then formalized within the Poisson-Boltzmann electrostatics augmented by the consistent inclusion of the charge dissociation of molecular groups residing on the surface of the entrapped macroions via charge regulation formalism. By solving the basic equilibrium equations in the linearized Debye-Hückel type approximation, we analyze the salient features of the inhomogeneous electrolyte distribution and macroion charge. We found that the surface charge asymmetry/symmetry of the macroions strongly affects the spatial profile of electrostatic potential. The effective screening length shows the non-monotonic behavior, arising from the complex interplay between the bathing external solution and macroion effective charges, which govern charge regulation equilibria. The total pressure at the nano-reactor enclosure boundary decreases monotonically as the enclosure radius and the ionic bulk salt concentration increase. Also, the resulting pressure is strongly influenced by the surface charge densities of the nano-reactor and the number of confined macroions.
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All authors Manit Klawtanong, Petch Khunpetch, Huaqiong Li, Shigeyuki Komura

Materials Science

Quantitative prediction of excitons in lattice-mismatched van der Waals heterostructures

Jakob Kjærulff Svaneborg, Mikkel Ohm Sauer, Amalie Helena Svaneborg et al. (+1 more)

Accurate modeling of dielectric screening in van der Waals (vdW) heterostructures is essential for predicting photonic and optoelectronic properties - yet conventional first-principles methods are often hindered by incommensurate lattices and prohibitive computational costs. In this work, we introduce the microscopic Quantum Electrostatic Heterostructure (mQEH) method. mQEH employs a hierarchical and systematically improvable basis set to describe potentials and induced densities, eliminating the need for arbitrary geometric cutoffs and ensuring accurate screening descriptions at all length scales. The mQEH method is combined with a layer projected Bethe-Salpeter Equation (BSE) to enable calculations of optical spectra of experimentally relevant lattice-mismatched vdW heterostructures. Applying the mQEH-BSE framework to a series of transition-metal dichalcogenide (TMD) heterobilayers, we obtain absorption spectra and momentum-indirect exciton energies in excellent agreement with experiment. The framework provides a computationally efficient route to predictive modeling and design of vdW heterostructures with tailored optical properties.
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All authors Jakob Kjærulff Svaneborg, Mikkel Ohm Sauer, Amalie Helena Svaneborg, Kristian Sommer Thygesen

Mesoscale and Nanoscale Physics

Tunneling-induced translation of intact $\pi$-radical clusters on Au(111)

Jacob D. Teeter, Kateryna Averchenko, Maximilian Eliasch et al. (+1 more)

The scanning tunneling microscope (STM) is a powerful tool for investigating and manipulating molecules on surfaces. We demonstrate with a low-temperature STM operated at 6.2 K the controlled manipulation of ternary clusters of persistent molecular $\pi$ radicals as a whole. The ternary clusters $-$ each self-assembled from three $\alpha,\gamma$-bisdiphenylene-$\beta$-phenylallyl (BDPA) molecules on Au(111) $-$ maintain their natural cluster structure throughout tip-induced translation and rotation relative to the surface. Sustained and repeated dragging of radical clusters is shown to facilitate the construction of artificial assemblies of several clusters. Our results provide new opportunities for the creation and investigation of radical-based spin assemblies on surfaces.
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All authors Jacob D. Teeter, Kateryna Averchenko, Maximilian Eliasch, Stefan Müllegger

Cosmology and Nongalactic Astrophysics

Evolving Dark Energy Is Vacuum Energy After All

Dong Ha Lee, Carsten van de Bruck, Eleonora Di Valentino et al. (+2 more)

We investigate a physically motivated model of dynamical dark energy arising from the non-perturbative topological structure of the Quantum Chromodynamics (QCD) vacuum. The model introduces no new fundamental field or propagating degree of freedom: the dark energy (DE) density emerges as a global vacuum response to an expanding spacetime. We develop the first comprehensive cosmological implementation of this QCD-DE scenario and confront it with current observations, including Planck, ACT and SPT-3G cosmic microwave background data, DESI DR2 baryon acoustic oscillation measurements, and Type Ia supernova samples from Pantheon+ and DES-Dovekie. We compare the model with $\Lambda\mathrm{CDM}$ and $w_0w_a\mathrm{CDM}$ cosmologies. The model provides an excellent fit to the data and reproduces the late-time DE evolution preferred by DESI. The model naturally predicts effective phantom crossing behaviour at intermediate redshifts ($z\sim0.67$) while avoiding the instabilities associated with phantom scalar fields. Using goodness-of-fit statistics and Bayesian model-selection tools, including Akaike and Deviance Information Criteria and Bayesian evidence estimated from Markov-Chain Monte Carlo chains, we find that the QCD-induced model is consistently favoured over $\Lambda\mathrm{CDM}$ for the full combination of early and late-time datasets. Unlike the conventional descriptions of dynamical DE, support for QCD-DE in Bayesian evidence remains more consistent across datasets, suggesting that a physically motivated departure from a cosmological constant may provide a more economical description of the expansion history preferred by current observations.
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All authors Dong Ha Lee, Carsten van de Bruck, Eleonora Di Valentino, Ludovic Van Waerbeke, Ariel Zhitnitsky

Mathematical Physics · Cross-listed from math.DG

From 2-covariant tensor fields to Poisson and Jacobi structures

Manuel de León, Xavier Gràcia, Rubén Izquierdo-López et al. (+2 more)

Poisson and Jacobi structures play a fundamental role in the geometric description of many systems arising in classical mechanics. In most cases, the corresponding bivector field is induced by a non-degenerate 2-covariant tensor field. In this paper, we present a unified framework for constructing the associated brackets by studying the Poisson and Jacobi structures induced by these tensors. More specifically, under suitable assumptions on the tensor, we derive a formula for computing the Schouten–Nijenhuis bracket of the associated bivector field in terms of the curvature of a certain distribution and the exterior derivative of a differential form. This formula provides the obstruction to the existence of a Poisson or Jacobi structure. To illustrate the theory, we recover the classical brackets associated with symplectic, locally conformally symplectic, contact, cosymplectic, and cocontact geometries. Finally, we characterise the conditions under which fat bundles and almost cosymplectic structures of order $p$ determine a Jacobi bracket.
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All authors Manuel de León, Xavier Gràcia, Rubén Izquierdo-López, Ángel Martínez-Muñoz, Xavier Rivas

Lattice Field Theory

A Finite-Volume Scheme for the Continuum Extrapolation of Lattice Step-Scaling in (2+1)D Hamiltonian U(1) Gauge Theory

Alessio Negro, Emil Otis Rosanowski, Lena Funcke et al. (+4 more)

We propose a finite-volume scheme to perform controlled continuum extrapolations of the lattice step-scaling function, a key ingredient for determining the running coupling in a Hamiltonian lattice gauge theory in small volumes. As a testbed, we employ a dual Hamiltonian formulation of pure U(1) gauge theory in (2+1) dimensions and an operator basis that remains efficient toward weak coupling. We describe the implementation of static external charges on the spatial lattice and study, using matrix product states, the resulting confining string, from which we extract the static potential and a force-based renormalized coupling. Using the proposed finite-volume scheme, we demonstrate a stable continuum limit of the step-scaling function on the lattice sizes accessible to present Hamiltonian simulations. The method is readily extendable to other gauge groups and dimensions, providing a pathway toward Hamiltonian step-scaling studies in other theories.
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All authors Alessio Negro, Emil Otis Rosanowski, Lena Funcke, Timo Jakobs, Karl Jansen, Paul Ludwig, Carsten Urbach

Nuclear Experiment

Probing flavor effects in the QCD parton shower using $\mathbf{{\rm D}^0}$-tagged jet angularities in proton$-$proton collisions at $\mathbf{ \sqrt{s} = 5.02}$ TeV

ALICE Collaboration

The ALICE Collaboration presents the first measurements of ${\rm D}^0$-tagged jet angularities in proton$-$proton (pp) collisions at $\sqrt{s} = 5.02$ TeV. Jet angularities are powerful substructure observables that characterize the angular and momentum distributions of particles within jets via tunable weighting parameters. Varying the angular parameter in jet angularities allows for a systematic probe of the sensitivity to collinear and soft radiation, enabling the study of flavor-dependent fragmentation and hadronization through comparisons of jets initiated by different partons. This paper reports ${\rm D}^0$-tagged and inclusive (gluon-dominated) charged-particle jet angularities with a resolution parameter $R=0.4$ in the low jet transverse momentum range ($10 < p_{\rm T}^{\rm ch. \, jet} < 20$ GeV/$c$), where charm-quark mass effects are most significant. At low angular weight, which emphasizes collinear radiation, ${\rm D}^0$-tagged jets exhibit smaller angularity values than inclusive jets. This provides evidence for the radiation suppression from massive quarks – a phenomenon known as the QCD dead-cone effect. As the angular weight increases, giving more emphasis to wide-angle radiation, the difference between ${\rm D}^0$-tagged and inclusive jet distributions decreases. This indicates that the modification is concentrated within the jet core rather than its edge. PYTHIA 8 simulations qualitatively reproduce both the angularity of ${\rm D}^0$-tagged and inclusive charged-particle jets, but reproduce the ${\rm D}^0$-tagged jet distributions better than those of inclusive jets, offering a powerful new constraint for models. These results provide insight into flavor-dependent fragmentation and establish an essential baseline for future studies of jet modifications in the quark-gluon plasma produced in heavy-ion collisions.
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Optics

Temporal dissipative solitons and optical frequency combs in coherently driven Kerr resonators

Stuart G. Murdoch, François Leo, Xiaoxiao Xue et al. (+2 more)

Kerr frequency combs have recently emerged as an exciting new photonic technology, with applications across science and engineering. Their formation within driven optical resonators that possess a Kerr nonlinearity is enabled through the rich landscape of localized nonlinear dissipative structures intrinsic to these systems. This article offers a comprehensive review of the physics that underpins these nonlinear comb-generating structures. Particular attention is placed on bright temporal cavity solitons and nonlinear switching waves – the canonical stable comb-generating states in the anomalous and normal dispersion regimes, respectively. Written as both a review and tutorial, the article also includes an in-depth treatment of the numerical methods required to simulate driven Kerr resonators, alongside a comprehensive discussion of the laboratory techniques used to experimentally realize and characterize Kerr combs.
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All authors Stuart G. Murdoch, François Leo, Xiaoxiao Xue, Stéphane Coen, Miro Erkintalo

Geophysics

Acceleration methods for the planar 3D ILSA hydraulic fracturing model

V. I. Shukalo, A. V. Valov and A. N. Baykin

Planar 3D models of hydraulic fracturing provide a practical balance between models with restrictive geometric assumptions and fully 3D simulators, capturing fractures with arbitrary planar footprints at moderate computational cost. Nevertheless, applications such as treatment design optimization and mini-frac test interpretation require large ensembles of simulations, for which the cost of planar 3D models remains a significant bottleneck. This work presents acceleration strategies for the planar 3D Implicit Level Set Algorithm (ILSA) to reduce simulation runtime while preserving numerical accuracy. A unified planar 3D ILSA scheme that consolidates the nested loops of the elastohydrodynamic solver and the front tracking algorithm into a single iterative process is introduced. A matrix splitting approach is applied to the linearized elastohydrodynamic system, moving the dense part of the elasticity operator to the right-hand side and yielding a sparse system matrix that can be solved more efficiently. Anderson acceleration is incorporated into the solution of the elastohydrodynamic system to improve convergence. A predictor–corrector scheme is additionally examined in combination with these methods. Each technique is evaluated individually and in combination on both the reference and unified schemes across five benchmark cases. Numerical experiments demonstrate that the unified scheme alone delivers an average 2.3x speed-up, reaching 3.8x for the Sandglass case. The combined application of all techniques achieves an average 4.2x speed-up and up to 14.4x for the Sandglass case. The schemes are also assessed during fracture closure, where the matrix splitting and Anderson acceleration prove most effective, together reaching up to 3.4x.
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Quantum Physics

Simulation of Non-Markovian Quantum Accelerated Dynamics via Time-Fractional Schrödinger Equation

Dongmei Wei, Junxiang Wang, Hanxiu Xu et al. (+2 more)

The Time-Fractional Schrödinger Equation (TFSE) is an effective tool for simulating the dynamics of non-Markovian quantum systems. The Quantum Speed Limit (QSL) time characterizes the minimum time required for the evolution of a non-Markovian quantum system. In this paper, Wei's TFSE is employed to simulate the non-Markovian quantum accelerated evolution process in the Resonant Dissipative Jaynes-Cummings (RDJC) model. By solving the QSL time of a time-fractional single-qubit open system, the enhancement mechanism of the system evolution speed induced by the non-Markovian memory effects of the environment is revealed. Further studies show that the optimized acceleration of the system evolution can be achieved by jointly regulating the fractional order, coupling strength, and photon number. Comparative analyses indicate that Wei's TFSE can accurately capture the non-Markovian accelerated dynamical features of the system over the entire fractional order range, whereas Naber's TFSE is applicable only within a limited fractional order interval. In addition, the comparisons of the average simulation time for calculating the dynamical trajectory of the excited-state probability demonstrate that Wei's TFSE has a significant simulation advantage in computational efficiency. Therefore, Wei's TFSE is more accurate and efficient for simulating the accelerated dynamics of non-Markovian quantum systems.
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All authors Dongmei Wei, Junxiang Wang, Hanxiu Xu, Cancan Chen, Jiaying Wu

High Energy Astrophysical Phenomena

A Whisper from Within: Response of a Pulsar Timing Array to an Internal Gravitational-wave Source

Houyuan Qi, Xian Chen, Lin Wang et al. (+1 more)

Millisecond pulsars (MSPs) are abundant in globular clusters (GCs) and probably also in galactic nuclei. They offer the potential to form a miniature pulsar timing array (mini-PTA) to detect nanohertz gravitational-wave (GW) sources located inside the array. Since the size of such an array is comparable to the wavelength of GW, the conventional plane-wave approximation becomes invalid, and near-field effects, including wavefront curvature, non-radiative self-field of the GW source, and direct perturbation of pulsar by GW, become significant. In this work, we incorporate these effects in a comprehensive model to calculate the timing residual induced by a GW source inside a mini-PTA. We also consider realistic GW source configurations in GCs (M15 and $\omega$ Centauri) and in galactic nuclei (Sgr A* and M31), and find that for MSPs located sufficiently close to the GW source (within a few wavelengths), the residual can reach $1~\mu\mathrm{s}$ in GCs and up to milliseconds in galactic centers, within the potential detection reach of current radio telescopes. Crucially, when the pulsar lies within a few GW wavelengths of the source, the non-radiative field dominates and causes the residual to rise much more steeply (between $1/r_e^2$ and $1/r_e^4$, where $r_e$ is the distance to the source) than the conventional far-field scaling ($1/r_e$). These results demonstrate that mini-PTAs in GCs or galactic nuclei can serve as powerful probes of otherwise invisible GW sources, including intermediate-mass and supermassive black hole binaries.
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All authors Houyuan Qi, Xian Chen, Lin Wang, Kuo Liu

Quantum Gases

Effects of interaction range on the mean-field dynamics of Bose polarons

Piotr Wysocki, Ubaldo Cavazos Olivas, Marek Tylutki et al. (+1 more)

We consider the three-dimensional Bose polaron problem in the regime of finite range interactions and competing length scales. Working in the reference frame of the impurity, we study both static and out of equilibrium properties of the system, in particular the transfer of momentum between the impurity and the host gas. We find that relaxation dynamics can occur via damped oscillations of the impurity velocity with simple dependence on the interaction strength. Furthermore, the equilibration process is sensitive to the type of the impurity-bath interaction. Specifically, interatomic forces describing ion-atom systems lead to much longer timescales and more pronounced oscillations in the strong coupling regime with respect to local interaction potentials. We also find that the effective masses can differ by a large amount between the two scenarios, even if the number of atoms in the polaron cloud remains similar for both cases.
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All authors Piotr Wysocki, Ubaldo Cavazos Olivas, Marek Tylutki, Krzysztof Jachymski

Solar and Stellar Astrophysics

Once more: Leaky MHD waves in coronal magnetic flux tubes

Hans Goedbloed and Rony Keppens

By a detailed comparison of leaky magnetohydrodynamic waves in coronal magnetic flux tubes with leaky electromagnetic waves in dielectric media it is shown that the latter kind may be called quasi-normal modes, since they can be regularised by a normalisation which systematically cuts off the contribution of the external homogeneous region, whereas such a possibility is forbidden for the former kind by the conservation of magnetic flux. Consequently, leaky magnetohydrodynamic waves cannot be systematically applied to coronal seismology, i.e. to the inverse spectral problem of determining the different equilibrium distributions of the fields by comparing the spectra they produce with the observed ones.
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High Energy Physics (Theory)

Leading UV Formula for Finite-Volume Vertex Operator Expectation Values in the Sine-Gordon Model from Kink NLIE

Arpad Hegedus and Apor Roth

We study the ultraviolet (UV) limit of finite-volume expectation values of vertex operators in the sine-Gordon model using the kink nonlinear integral equation (NLIE) description of the conformal limit. By analysing the integrable formulation of vacuum expectation values in the small-volume regime, we conjecture an explicit analytic expression for the leading asymptotic term in the small-volume expansion, formulated in terms of kink functions. This establishes a direct connection between the integrable finite-volume description and the expected conformal asymptotics determined by the 3-point functions of the underlying conformal field theory (CFT). The proposed formula is tested against the analytic expression known from complex Liouville conformal field theory using high-precision numerics, showing agreement to at least 19 significant digits.
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Quantum Physics

All-valid-state HOBO encoding for constrained combinatorial optimization on NISQ devices

Juncheng Wang, Takumi Kanezashi, Daisuke Tsukayama et al. (+5 more)

Continued advancements in quantum computing have stimulated growing interest in translating quantum technologies into real-world applications. Consequently, the investigation of practically motivated NP-hard problems is of significant value. This study investigates the performance of a variational quantum eigensolver (VQE) in addressing the traveling salesperson problem (TSP) through noiseless simulations representative of noisy intermediate-scale quantum (NISQ) devices using higher-order binary optimization (HOBO) encodings. We construct a HOBO Hamiltonian with an efficient binary representation and propose an all-valid-state HOBO (AVS-HOBO) scheme based on cyclic mapping that eliminates one penalty term and reuses states that would otherwise be invalid. Using TSP instances of up to 20 cities, we compare the original HOBO and AVS-HOBO encodings from multiple perspectives, including the energy convergence behavior and the approximation, tour-length, and feasibility ratios. In addition to simulations, we perform computations on real quantum hardware with different device architectures, where we not only compare the performances of different chips but also investigate the effects of different error-mitigation methods on actual quantum machines. The results indicate that AVS-HOBO encoding enhances the practical reliability of VQE on NISQ devices and improves scalability for larger TSP instances, with broader applicability to constrained quantum optimization problems.
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All authors Juncheng Wang, Takumi Kanezashi, Daisuke Tsukayama, Koki Awaya, Reo Saito, Jun-ichi Shirakashi, Tetsuo Shibuya, Hiroshi Imai

Mathematical Physics

Dirac structures on tangent bundles: a geometric framework for variational principles, constrained dynamics, and symmetry reduction

Hiroaki Yoshimura

We introduce a Dirac structure on the tangent bundle of a configuration manifold, called a Lagrange–Dirac structure, which is naturally induced by the Lagrangian two-form associated with a (possibly degenerate) Lagrangian and a constraint distribution. This structure provides a unified geometric framework for Lagrange–Dirac dynamical systems, encompassing nonholonomic, degenerate Lagrangian, and symmetric systems. In the hyperregular case, the system recovers a first-order formulation of the Lagrange–d'Alembert equations. Although nonholonomic dynamics does not preserve the Lagrangian two-form, we show that the underlying Lagrange–Dirac structure is preserved up to gauge transformations, yielding a natural gauge covariance property. We also formulate an intrinsic variational principle directly on the tangent bundle, referred to as the Lagrange–d'Alembert–Dirac principle, which recovers Hamilton's principle in the unconstrained case and the Lagrange–d'Alembert principle in the hyperregular constrained case. Furthermore, we develop a reduction theory for systems with Lie group symmetry, deriving a reduced Lagrange–Dirac structure over the Lie algebra that yields the Euler–Poincaré–Dirac equations and a corresponding reduced variational principle. Finally, we illustrate the theory through examples including charged particles, electric circuits, and systems with Lagrangians linear in velocity, and present an infinite-dimensional extension to ideal fluids that naturally incorporates the incompressibility constraint and recovers the Euler equations.
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Quantum Physics

The use of Peres lattices in periodically driven systems

Lukáš Honsa, Jan Střeleček, Jakub Novotný et al. (+1 more)

We demonstrate the strength of the method of Peres lattices in periodically driven quantum systems. The method, which has previously been used mostly in stationary systems, enables us to efficiently detect resonances in the driven system, to monitor the onset of chaos, and to recognize critical properties of the Floquet modes. It also allows quick comparisons of the spectra of Floquet modes for various driving Hamiltonians and transparent tests of the iterative approximation techniques based on effective stationary Hamiltonians.
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All authors Lukáš Honsa, Jan Střeleček, Jakub Novotný, Pavel Cejnar

Astrophysics of Galaxies

A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE) XX. Star formation in the tidal tail of NGC 4254

A. Boselli, A. Lupi, P. Serra et al. (+26 more)

ALMA 12CO(1-0) observations of 42 star-forming regions located outside the disc of the Virgo Cluster galaxy NGC4254 within an HI gas tail produced during the galaxy's interaction with another cluster member have revealed the presence of ten giant molecular clouds (GMCs) in four of these regions. All of the GMCs were resolved at the angular resolution of the observations (~160 pc) and have molecular gas masses of M(H2)~(0.8-2.0)x10^6} Mo. These ten clouds are characterised by gas column densities [S(H2)~10 Mo pc^-2] and velocity dispersions [sigma_v(CO)~3-12 km s^-1] respectively lower and comparable to those encountered in similar GMCs in the Milky Way. They follow the relation between the gas column density and the star formation activity (Schmidt law) derived using similar data over the stellar disc of NGC4254 and other local and Virgo cluster galaxies. With analytic calculations and tuned simulations, we show that these clouds are unstable and thus expected to dissolve on relatively short timescales (~10-30 Myr). We show that they probably formed after the collapse of dense gas clouds in the HI gas tail stripped during the gravitational interaction that the galaxy suffered several hundreds millions of years ago. The clouds are short-lived and isolated given the low density of the surrounding intracluster medium, which cannot confine the gas expelled by stellar feedback. We discuss the implications of these results in the general context of the fate of stripped gas in hostile cluster environments.
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All authors A. Boselli, A. Lupi, P. Serra, P. Andreani, F. Calura, M-A. Miville-Deschenes, G. Hensler, M. Boquien, M. Fossati, S. Boissier, J. Braine, P. Cote, J.C. Cuillandre, F. de Gasperin, H. Edler, L. Ferrarese, G. Gavazzi, S. Gwyn, J. Hutchings, K. Kianfar, A. Longobardi, E.S. Mangola, S. Martocchia, E. Peng, H. Plana, J. Postma, J. Roediger, Y. Roehlly, M. Sun

Optics

A unified resource-pool architecture for high-dimensional direct-detection optical communication

Jingze Liu, Zhijuan Gu, Xinyang Yu et al. (+12 more)

Increasing optical communication capacity without proportionally increasing receiver complexity remains a key challenge for direct-detection links. Conventional systems typically assign wavelength, polarization and intensity to fixed, separately recovered functions, so that alphabet expansion is accompanied by additional demultiplexing, polarization handling, receiver branches and electronic processing. Here we introduce a unified resource-pool architecture for high-dimensional direct-detection optical communication, in which wavelength, polarization and intensity are jointly organized as a composite optical symbol space and recovered through optical-domain joint projection rather than dimension-by-dimension separation. The receiver is implemented with an integrated disordered photonic processor that transforms each composite optical state into a reproducible multi-output electrical fingerprint for single-shot direct recovery. In a dual-wavelength transmission experiment, the system resolves 4096 composite symbols, corresponding to 12 bits per symbol slot, with a bit error rate of 4.25e-4 after 10 km standard-fiber transmission. Additional experiments demonstrate dense polarization alphabets, wavelength-indexed state-space expansion and high-launch-power operation over hollow-core fiber. These results establish disorder-enabled joint projection in an integrated photonic processor as a route to hardware-efficient high-dimensional direct-detection communication beyond conventional dimension-partitioned receiver architecture.
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All authors Jingze Liu, Zhijuan Gu, Xinyang Yu, Ziwen Zhou, Zhuyixiao Liu, Mingming Zhang, Yuxuan Xiong, Peng Li, Zhongyao Luo1, Jiajie Yuan, Hao Wu, Zhipei Sun, Siqi Yan, Yu Yu, Ming Tang

Quantum Physics

Optimal Shadow Estimation with Minimal Measurement Settings

Zhiyao Yang, Datong Chen and Huangjun Zhu

Shadow estimation is a powerful framework for predicting quantum properties from randomized measurements. While $3$-design protocols achieve optimal worst-case performance, the minimal number of measurement bases required for such optimality has remained open. Here we prove that $\Theta(d^2)$ measurement bases are both necessary and sufficient for worst-case optimal shadow estimation and construct an explicit basis family. In stark contrast, any state $2$-design already suffices for average-case optimality: the mean squared shadow norm of normalized observables is bounded by a universal constant, and we prove strong concentration for Haar-random states, yielding constant sample complexity for generic pure-state fidelity estimation. Easily implementable $2$-designs – from mutually unbiased bases, cyclic measurements, or shallow $\mathcal{O}(\log n)$-depth circuits – enable optimal average-case protocols with remarkably simple measurement strategies. Our results establish a fundamental complexity separation: worst-case estimation requires $\Theta(d^2)$ bases, whereas average-case performance requires only $\Theta(d)$ bases, with broad implications for quantum information theory and near-term experiments.
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High Energy Physics (Phenomenology)

Two Flavon Froggatt-Nielsen Models with Genetic Algorithms

Miguel Crispim Romão and Stephen F. King

We present the first systematic and comprehensive scan of two-flavon Froggatt-Nielsen (FN) models, employing artificial intelligence techniques to explore the high-dimensional, mixed discrete-continuous parameter space. Extending the standard single-flavon FN framework to a two-flavon setup in which separate flavon fields couple independently to the up- and down-type sectors, we demonstrate that the relative phase between their vacuum expectation values (vevs) provides a natural and generic source of CP violation absent in single-flavon models. To explore this enlarged model space, we cast the search for phenomenologically viable models as a multi-objective optimisation problem, formulating each experimental constraint as a separate objective, and employ the Non-dominated Sorting Genetic Algorithm III to simultaneously fit all 18 FN charges, 45 Wilson coefficients, and flavon parameters to both the quark and lepton sectors. Our approach requires no separate training phase and identifies phenomenologically viable models orders of magnitude faster than prior reinforcement learning methods. Imposing experimental constraints on CKM and PMNS mixing angles and CP phases, charged fermion masses, and neutrino squared-mass differences, we discover over $100\,000$ unique viable models with a remarkably low duplication rate, indicating that the space of valid two-flavon FN realisations has not been exhausted. Both Normal and Inverted neutrino mass squared orderings are realised, with the relative hierarchy between the flavon vevs producing qualitatively distinct predictions for the effective neutrinoless double beta decay mass $m_{ee}$. We further demonstrate the existence of minimal FN realisations with maximal flavon exponent as small as three, and of models reproducing charged fermion masses to within $6\%$ without any dedicated continuous parameter optimisation.
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High Energy Physics (Phenomenology)

NLO QCD and EW corrections to semileptonic vector-boson scattering at the LHC

Ansgar Denner, Robert Franken, Daniele Lombardi et al. (+1 more)

Vector-boson scattering with semileptonic final states has recently been measured at the LHC, and future experiments are expected to further increase the precision of its measurement, calling for adequate theoretical predictions. In this work, we present a calculation of the NLO QCD and electroweak corrections to the process $\text{p}\text{p} \to \ell^+ \nu_\ell + 4\text{j}$ in two different fiducial regions relevant for vector-boson scattering. In a fully off-shell calculation, we provide results for the leading electroweak contribution of $\mathcal{O}\left(\alpha^6\right)$ and the corresponding corrections of $\mathcal{O}\left(\alpha^7\right)$ and $\mathcal{O}\left(\alpha_\text{s} \alpha^6\right)$ for fiducial cross sections and a selection of differential distributions.
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All authors Ansgar Denner, Robert Franken, Daniele Lombardi, Santiago Lopez Portillo Chavez

Cosmology and Nongalactic Astrophysics

Finite-Core Signatures in LISA-Band Wave-Optics Lensing by Low-Mass Dark Matter Halos

Dejiang Li, Tonghua Liu, Kai Liao et al. (+3 more)

LISA-band gravitational waves from massive binary black holes can be diffractively lensed by low-mass dark matter halos and subhalos, so their frequency-dependent amplification can probe the inner density profile. We isolate the generic finite-core part of this signal by comparing fixed-mass Navarro-Frenk-White (NFW) and cored-NFW lenses and propagating both profiles to the complex wave-optics amplification factor. A finite core smooths the time-delay response and reshapes the diffraction peak; an NFW template with a lower concentration can mimic part of the effect, but structured complex residuals remain after time and phase alignment. The residual peaks for intermediate cores, $r_c/r_s\simeq0.25$–$0.3$. An SIDM-inspired isothermal-core profile gives the same qualitative response, showing that the signal is not an artifact of one cored parameterization. For a fiducial LISA source, an appreciable mismatch requires favorable near alignment and $M_{\rm vir}\gtrsim 10^7M_\odot$. The result is a finite-core baseline for isolated line-of-sight halos and for subhalos perturbing strongly lensed macro-images.
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All authors Dejiang Li, Tonghua Liu, Kai Liao, Beining Xia, Cuihong Wen, Jieci Wang

High Energy Physics (Phenomenology)

$\Xi_{cc}^{++}-\Xi_{cc}^{+}$ Transitions as a Two-Charm-Selective Portal to Ultra-Low-$Q$ Charged Currents

Yong Du

The recent LHCb observation of $\Xi_{cc}^{+}$ opens the ultra-low-$Q$ transition $\Xi_{cc}^{++}\to\Xi_{cc}^{+}$ as an experimentally motivated null test of charged-current new physics. Our two- and three-body analyses show sensitivity to effective baryon-level couplings of $\mathcal{O}(10^{-6}-10^{-7})$ for MeV-scale recoil momenta. We establish a practical no-go result for a universal light charged scalar $\phi^+$: with a first-generation $\phi^+\bar u d$ coupling, existing electroweak-precision and beta-decay constraints are parametrically stronger than the projected LHCb sensitivity. We then identify a two-charm-selective charged-current portal whose leading operator has a nonzero matrix element in doubly charmed baryons but vanishes at leading order in pions, nucleons, nuclei, and singly charmed mesons. In this class of models, $\Xi_{cc}^{++}\to\Xi_{cc}^{+}$ transitions can provide the leading direct probe of the portal interaction.
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