Papers

Structures that capture functionality in the form of animate or intelligent machines have the potential to transform modern engineering applications. Animation and embedded intelligence are typically realised by integrating advanced capabilities such as reversibility, adaptive responses and learning directly into the materials themselves. Currently, the majority of adaptive material systems rely on predefined adaptive designs combined with in-service, electronics-based computing to dynamically modify the structural behaviour. However, structural configurations with interconnected adaptable nodes are able to approximate continuous functions, providing new possibilities and opportunities than classical metamaterials and computational materials. We discuss here the potential to design load-bearing engineering materials with trainable physical parameters and neural network-inspired morphologies, embedding intelligence directly into their structure, a concept we define as Engineering Material Neural Networks (EMNNs) as a subcategory of Physical Neural Networks. In this perspective, we first establish the foundational concept of EMNNs; we then detail the mechanical and multifunctional properties required for such structural configurations. Finally, we evaluate existing and emerging engineering materials that hold promise for enabling this innovative approach. Key material candidates for realising EMNNs include composites, architected, biological and engineering living materials. We also outline future directions in materials science and structural engineering for developing EMNNs.

Phase retrieval - recovering a complex-valued field from intensity measurements - is typically solved using variants of the Gerchberg-Saxton (GS) algorithm, understood as alternating projections between measurement planes. Meanwhile, modern computational imaging increasingly relies on gradient-based optimization and automatic differentiation. Here we show that these two approaches are mathematically identical: the GS magnitude replacement step is exactly a unit gradient descent step on an amplitude least-squares loss. This equivalence enables seamless integration of classical phase retrieval with differentiable physics pipelines. We further identify two complementary probabilistic interpretations of this equivalence: globally, the amplitude loss is the negative log-likelihood under Gaussian amplitude noise; locally, each projection step arises as a Bayesian update with the propagated field as prior. The local view provides qualitative guidance for relaxation in iterative phase retrieval.

The development of modern high-energy astrophysics has been deeply intertwined with advances in particle detector technology. Guido Barbiellini Amidei (1943-2024) played a pivotal role in bridging experimental particle physics and astrophysical observation. His scientific career spanned over four decades, from early electron-positron collider experiments at ADONE and LEP (DELPHI) to space based missions such as AGILE, Fermi, and PAMELA. This memorial paper reviews the evolution of high-energy astrophysics as a detector-driven science, highlighting key domains where Barbiellini left an indelible mark: gamma-ray astronomy, cosmic-ray physics, and antimatter studies. We discuss his personal contributions to silicon tracking, calorimetry, data analysis, and his leadership in international collaborations. The conceptual impact of his interdisciplinary approach is examined, and future perspectives in the observation of the high-energy universe are outlined, recognizing that the path forward is built on the foundations he helped lay

We demonstrate distributed acoustic sensing on deployed buried cable leveraging laser frequency stabilization and probing code optimization. Our results confirm the capability to accurately localize weak events with high resolution and sensitivity over 80 km.

Virtual accelerators and digital twins are increasingly essential tools for accelerator operations, controls development and verification, and model-based optimization. However, current implementations are often tightly coupled to specific simulation codes, facilities, and applications, resulting in fragmented, ad hoc solutions that are difficult to reuse or extend. To address this, we expand the LUME Python package to include standardized implementation and deployment of virtual accelerators and digital twins across heterogeneous simulation backends and control system interfaces. At the core of this change is the introduction of LUMEModel abstraction, which defines a fixed, simulator-agnostic API and a variable system that encodes metadata such as units and data types/validation. This design enables standardized interaction with physics-based simulators, surrogate models, and differentiable simulations, while supporting both Python-native workflows and IOC-based operation via EPICS using the lume-pva package. Facility- and simulator-specific details are encapsulated through extensible transformer layers, allowing consistent control-system semantics to be mapped onto diverse simulation engines. We describe the LUMEModel architecture, variable system, and package ecosystem, and present representative use cases including model interchangeability, staged and chained simulators, and continuous integration testing. This work will make implementing and using virtual accelerators easier and more flexible.

Neural ordinary differential equations (neural ODEs) have rapidly gained prominence as a powerful and unifying framework for conceptualizing artificial neural networks, elegantly connecting the continuous-time modeling of dynamical systems with the discrete, data-driven paradigm of modern deep learning. Beyond their practical advantages they offer fresh theoretical insights into the training and generalization properties of neural networks. The distinctive feature of this framework is its dual dynamical nature: inference dynamics, which govern the ODE evolution during forward computation, and training dynamics, which control the optimization of model parameters. This makes neural ODEs a particularly well-suited theoretical framework for studying a large variety of settings such as multi-layer neural networks (ResNets for example), autoregressive models (with next-token generation dynamics), generative models, and recurrent neural networks in theoretical neuroscience. In this work, we introduce a theoretically grounded class of models for studying neural ODEs trained via online stochastic gradient descent. We solve the training dynamics of these models via dynamical mean field theory and derive learning curves in the high-dimensional limit.

We consider double Wick rotation in field theories, which analytically continues the time coordinate, and then reinterprets one of the spatial directions as the new Lorentzian time. We show that if Lorentz-invariance is absent, Wick-connected theories are no longer necessarily equivalent. Focusing on flat spacetime, we study the propagating modes, unitarity and renormalizability of such Wick-connected theories, and provide criteria for when such notions fail to translate.

In this paper, the class of randomised mixed labyrinth fractals is introduced. It is a class of finitely ramified Sierpinski carpets that generalize mixed labyrinth fractals. The structures are generated by randomly selected labyrinth patterns with fixed selection probabilities at each iteration level, offering a flexible framework to study fractal topology, arc dimensions, and shortest path properties. Here, the focus lies on analysing how the randomised mixing of patterns - specifically their shape, symmetry, and path geometry - effects arc dimensions, path lengths, and isotropy restoration. The study reveals that isotropy, previously shown for self-similar fractals, extends to the randomised mixed class. Various scaling behaviours of shortest path dimensions with respect to the mixing probability are identified, including linear and nonlinear monotonic trends, as well as transitions with maxima. The approximated path matrix is proposed as an efficient alternative to extensive iterative simulations, reliably reproducing statistical results. The findings highlight the relevance of pattern properties in determining fractal structures and dynamics and suggest applications in physical systems such as diffusion, signal processing, and antenna design.

Temporal interfaces, defined by abrupt changes in material properties, break temporal translational symmetry and enable wave phenomena fundamentally different from those at spatial interfaces. Unlike spatial scattering, temporal scattering preserves momentum rather than energy, leading to instantaneous frequency shifts governed by the dispersion relations on either side of the interface. Existing studies in elastic media have mainly considered non-resonant materials, and allow only one-to-one frequency conversion across temporal interfaces. Here, we propose temporal interfaces formed by the sudden activation of local resonators in elastic metamaterials, which induces a transition from non-resonant to resonant dispersion. We demonstrate that such interfaces can induce frequency splitting among scattered waves and elucidate how the scattered-wave amplitudes are governed by the weighted modal correlation coefficients and impedances. Moreover, a novel temporal evanescent mode, characterized by spatial stationarity and temporal decay is demonstrated after the interface, which is well explained by the negative effective modulus evaluated at imaginary frequencies. These findings establish a foundational understanding of wave dynamics at temporal interfaces involving resonant materials, open new opportunities for wave manipulation in time-varying solids.

We study the weak magnetic and electric dipole moments of the $\tau$ lepton as precision tests of the Standard Model (SM) and probes of heavy New Physics (NP). We present an updated SM prediction for the $\tau$ weak magnetic dipole moment at one loop, including a careful assessment of theoretical uncertainties from electroweak scheme dependence. Working within the SM Effective Field Theory, we derive comprehensive current constraints on the $\tau$ dipole operators from a combination of observables: the $\tau$ weak and electromagnetic dipole moments, high-mass Drell-Yan tails at the LHC, $Z$ partial decay widths, and the electron electric dipole moment. Finally, we assess the prospects of measuring the SM value of the $\tau$ weak magnetic moment at the FCC-$ee$ Tera-$Z$ run, and project the sensitivities of the leading observables to heavy NP at FCC-$ee$ and HL-LHC, incorporating informed assumptions about improvements of systematic uncertainties. We find that the $\tau$ weak dipole moments are already among the leading probes of the $\tau$ dipole operators, and will become increasingly dominant at future colliders.

This paper studies photometric and spectropolarimetric variability of HD210684 in order to derive its magnetic properties, rotational period, evolutionary stage, and global stellar parameters. The Discrete Fourier Transform is used to measure frequencies and amplitudes of periodic signals present in light curves of HD210684. Evolution models are calculated with MESA, while roAp type pulsations are simulated with GYRE. The values of $T_{eff}$, log(g), $v\sin{i}$, and radial velocity (RV) are derived from the best fit of Balmer line profiles using FITSB2. The Least Square Deconvolution (LSD) method is applied to available Stokes I&V spectra to measure the mean longitudinal magnetic field <Bz> and RV. Detailed analysis of photometric variability reveals rotational modulation with period P=5.02188$\pm$0.00005d and splitting of high-overtone pulsations that corresponds to the same rotational period. Derived <Bz> measurements also show periodic variability with P=5.02188d, but this variability appears to be different from the one predicted by a centred magnetic dipole model. We have determined the inclination angle between the line of sight and the rotation axis to be $i = 31^{\circ} \pm 2^{\circ}$, and the angle between the rotation and magnetic dipole axes as $\beta= 77^{\circ} \pm 3^{\circ}$. Simulations of stellar pulsations constrain $\log T_{eff}$<3.85 and show that our best fitting model depends on whether the observed modes are $\ell = 1$ or $\ell =2$. Considering the derived value of $\beta$, we prefer the best fit model with $\ell =2$ mode, which predicts that HD210684 lies on the main sequence with an age of approximately 1.45Gyr. The best fit of Balmer line profiles has resulted in higher values of $T_{eff}$ and log(g) for spectra acquired at rotational phases $\varphi$= 0.14 - 0.39 suggesting visibility of an area with higher surface temperature.

An information theoretic analysis is done for the isotropic harmonic oscillator potential within the Dunkl-Schrödinger framework in spherical coordinates. Starting from the exact analytical eigensolution, various quantum information measures such as Shannon entropy, Rényi information, Tsallis entropy are derived. Besides, their relative measures like relative Shannon, relative Rényi, relative Tsallis as well as corresponding divergences (Jensen-Shannon, Jensen-Rényi, Jensen-Tsallis) are also obtained. In order to get Shannon entropy, a novel factorization method is introduced. This is facilitated through the use of well-known weighted Lebesgue measure. The results from the Dunkl case agree exactly with the non-Dunkl scenario, when Dunkl parameters vanish. The reflection operators and Dunkl parameters considerably influence the above measures. These are portrayed in graphical forms.

RAMSES is an adaptive mesh refinement (AMR) astrophysical simulation code that generates high-resolution multiscale data. However, its native binary output format is not directly compatible with standard visualization tools, making efficient analysis challenging. We present Chhavi, an open-source Python tool that converts RAMSES outputs into the VTKHDF format for direct use in visualization platforms such as ParaView. The tool reconstructs the AMR hierarchy, preserves key physical fields including density, pressure and velocity, and organizes them into a structured representation suitable for multi-resolution visualization. The conversion is validated using the three-dimensional Sedov blast wave test case. Quantitative evaluation through radial profile comparison and Lin's concordance correlation coefficient demonstrates strong agreement between the original and converted datasets, confirming both physical and structural fidelity. Chhavi provides a scalable bridge between RAMSES simulation outputs and modern visualization workflows, supporting efficient and reproducible analysis in computational astrophysics.

We present a joint analysis of the processes $e^+e^- \to J/\psi\pi^+\pi^-$ and $e^+e^- \to J/\psi K^+K^-$ at center-of-mass energies from 4.13 to 4.36 GeV. The amplitudes are constructed using the Dalitz-plot decomposition formalism, with the $e^+e^-$ energy dependence encoded through the $Y(4220)$ and $Y(4320)$ resonant structures together with a nonresonant production mechanism. The scalar $\pi\pi/K\bar K$ final-state interaction is treated dispersively using a coupled-channel Omnès representation. This allows us to describe the measured total cross sections and one-dimensional invariant-mass distributions with a single set of energy-independent parameters. We find that a purely resonant description of the BESIII data is insufficient, requiring a nonresonant term at the amplitude level which undergoes $\pi\pi/K\bar{K}$ rescattering. Within the present isobar model, we extract Breit-Wigner parameters for the $Z_c(3900)$, $Y(4220)$, and $Y(4320)$ states, and determine the corresponding subprocess cross sections.

In this work we show that long-range interactions can be significantly beneficial for implementing shortcuts to adiabaticity (STA) in many-body open quantum critical systems driven out of equilibrium, as well as for charging quantum batteries in the presence of dissipation. In sharp contrast to short range interactions where passage through criticality may demand STA control with non-zero interactions between infinitely distant spins, using the example of a Kitaev chain with long-range couplings, we find that the corresponding control may involve involve interaction strength with decays algebraically with distance. In case of non-unitary control, the advantage of long-range interactions manifest through reduction in the cost of STA. We further propose a modified STA technique aimed at charging a quantum battery in the presence of dissipation, in which case long-range interactions may enhance the resultant ergotropy. Our results establish long-range interactions as a valuable resource for quantum control, with direct implications for quantum technologies.

In a recent paper, Arxiv:2605.23077, we have demonstrated that (conformal) Killing vectors give rise to stealth vector solutions of a specific bumblebee-type Proca theory supplemented by fine tuned curvature terms. Here we show that such a construction readily generalizes to hidden symmetries encoded in (conformal) Killing-Yano tensors, giving rise to the corresponding p-form stealth solutions. Similar to what happens with Killing vectors, the construction works on any background, providing a "physical visualization" of its symmetries. Several examples of spacetimes with so constructed p-form stealth hair are presented.

Interplanetary coronal mass ejections (ICMEs) carry magnetic clouds (MCs), large-scale structures with average radial widths about a fifth of an astronomical unit at Earth's orbit. ICMEs display substructures in white light images and reveal rich dynamics across many spatial scales when directly measured by spacecraft. A spacecraft encounter with an ICME can result in smoothly rotating MC intervals or less organised magnetic obstacle (MO) ones. We investigate how the interplay of expansion, turbulence, and internal cloud dynamics affects magnetic cloud properties, which are reflected in the plasma signatures measured by spacecraft. We perform high-resolution 2.5D MHD simulations of a magnetic flux rope cross-section, which is embedded in the turbulent, expanding solar wind with the expanding box model. We probe the local plasma properties, and thus the flux rope signatures and angular coherence, with virtual spacecraft. Our simulations reproduce clear and stable MC signatures when the flux rope core is intercepted by virtual spacecraft. Disordered MO signatures appear at the edges of the flux rope, and are attributed to both expansion and turbulent transport. We vary some key physical parameters of the flux rope and the environment to understand their effect on the observed coherence and signatures. The pace of the expanding flow controls the angular extent of MC signatures, whereas the intensity of interplanetary turbulence controls how asymmetric and distorted the flux rope appears at 1 AU. The geometry of spacecraft encounters determines whether MC or MO signatures are observed. The presence of a magnetic structure which can result in MO signatures is strongly controlled by the flux rope's initial/early magnetic configuration: MO signatures can only be observed when the axial flux rope field is spatially not well confined by the rope's own magnetic tension, and disappear otherwise.

Continuous-variable quantum key distribution (CV-QKD), which uses quadratures of the electromagnetic field, enables practical quantum communication using standard telecommunication technologies. Unidimensional CV-QKD (UD-CVQKD) simplifies the implementation by restricting modulation to a single quadrature. In this work, we experimentally demonstrate a free-space Gaussian-modulated UD-CVQKD system operating under a high detector electronic-noise regime (1.4 shot-noise units). The system employs polarized coherent states with signal and local oscillator co-propagating in the same spatial mode in orthogonal polarizations, ensuring stable interference. System security is analyzed under both untrusted (UTD) and trusted (TD) detector noise models. While no positive secret key rate is obtained under the UTD model, the TD model enables secure key generation over a finite range of modulation variances, highlighting the critical role of detector trust in high-noise conditions. A maximum secret key rate of 270 kbps is achieved at an optimal modulation variance of 11.57. Furthermore, secure operation requires high-transmittance (low-loss) channels under such noise conditions. This study demonstrates the practical feasibility of free-space UD-CVQKD in realistic high electronic-noise detection constraints and highlights detector electronic noise as a key limiting factor in practical systems.

In Momentum-resolved Scanning Transmission Electron Microscopy (4D STEM), a convergent electron beam is raster-scanned across a think specimen in 2D in real space. The corresponding 2D diffraction pattern, in momentum space, to each point is recorded, forming a 4D data set. Information decoding process can follow thereafter to produce an image of the specimen in real space. Ptychography is reconstruction algorithm that allow the extraction of the probe wavefunction and the multiplicative object transmission function of the specimen. Ptychography is implemented through direct and iterative schemes. Some of which are the extended Ptychographic Iterative Engine (ePIE), the Wigner Distribution Deconvolution (WDD) and the simpler version of WDD, the Single Side-Band (SSB). This thesis gives an overview of STEM ptychography giving examples of its experimental and simulated implementations. The different ptychographic reconstruction methods are explored in a mathematical framework when applicable. Finally, an SSB reconstruction was made using an original script for simulated data of MoS2 monolayer. Moreover, four-dimensional data was recorded using a STEM instrument. A natural step following this research would be the implementation of the WDD algorithm.

Two analytical models for sizing the toroidal field coils and central solenoid of a tokamak are developed within the D0FUS system code: a pedagogical thin-cylinder model and a refined thick-cylinder and winding packs model. The refined model shows good agreement with six reference machines and the MADE magnet design code. When the high-field design space is explored for DEMO-class power plants (2 GW of fusion power, Q = 40, tplateau = 2 h), pushing the peak field at the Toroidal Field (TF) coil conductor up to Bmax = 20 T, the radial build emerges as the dominant constraint: in fact, in the baseline wedging/316L configuration, no viable design can be found beyond 20 T, making alternative strategies necessary. The primary levers identified are high-strength steels (e.g CHSN01), alternative mechanical architectures (bucking, plug), and reductions of the effective Central Solenoid (CS) flux demand (for example through auxiliary heating during ramp-up), each carrying an impact of the same order of magnitude on the minimum feasible major radius. Secondary optimisations (conductor shape, radial grading) are shown to provide additional but more modest gains. When all favourable levers are combined (CHSN01, bucking, etc.), compact machines (R0 < 4 m) appear feasible. This suggests that, provided one accepts the associated risks of combining new approaches (CHSN01, bucking, etc.), high-temperature superconductors could unlock the path to compact electricity generating tokamaks.

We present realistic calculations within the density functional plus cluster dynamical mean-field formalism indicating that the physics of the the bilayer Ruddlesden-Popper nickelates is to a significant extent controlled by interlayer "dynamical singlets” which are formed from the $3z^{2}-r^{2}$ orbitals singly occupied by electrons and are hybridized with itinerant planar $x^{2}-y^{2}$ orbitals. The hybridization is found to respond differently to hydrostatic pressure and to epitaxial strain, capturing the experimentally observed dichotomy between bulk single crystals and epitaxial thin films and reproducing several experimental results including angle-resolved photoemission and transport measurements.

We study the low-energy excitations of the three dimensional spin glass through a large-scale Monte Carlo simulation on lattices up to $L=18$. We find smooth extrapolations down to zero temperature, which, in the case of the energy and of the link overlap, can be directly – and favourably – compared with previous investigations featuring ground states (i.e., at zero temperature). The best fit for the fractal dimension of the excitations is provided by Replica-Symmetry Breaking theory, but we also consider the alternative TNT description. The $P(q)$ is found to verify the Parisi-Toulouse temperature scaling. Our data provides a spectacular confirmation of the overlap-equivalence hypothesis.

Clinical observations of dry eyes reveal that tear film breakup is associated with spatial variations in corneal wettability arising from non-uniform mucin coverage. Motivated by these observations, we develop a thin-film model to investigate the influence of heterogeneous wettability on tear film stability. Heterogeneity in mucin coverage is incorporated through variations in the Hamaker constant and slip length along the corneal surface. Two representative forms of spatial heterogeneity are considered: a periodic step variation representing sharply localised mucin-deficient patches and a smoothly varying sinusoidal distribution representing gradual changes in glycocalyx. The steady states are obtained by a balance between capillary and van der Waals forces. A linear stability framework based on Floquet-Bloch theory and a discretised eigenvalue approach is developed to account for the periodic coefficients in the linearised equations. We show that heterogeneous wettability induces coupling between perturbation modes. The most unstable wavenumber and the maximum growth rate decrease with increasing mucin coverage fraction. However, both increase with increasing Hamaker constant contrast between mucin-rich and mucin-deficient regions. Nonlinear simulations reveal that rupture preferentially localises within mucin-deficient regions irrespective of the initial film thickness. The rupture location is governed by the spatial distribution of disjoining pressure rather than the initial perturbation. The predicted rupture dynamics are consistent with clinical observations where rupture location is invariant and the rupture times obtained from the model are in good agreement with clinically reported values. These findings demonstrate that spatial heterogeneity in wettability plays a decisive role in tear film instability and must be incorporated in tear film dynamics models.

Optimal conditions for unidirectional coupling in quasi-phase-matched non-Hermitian systems are analyzed for both autonomous and externally driven configurations. The quasi-phase-matched coupling mechanism is due to periodic modulation of the real and imaginary parts of the coupling interface, which results in unequal coupling coefficients between interacting waves. The conventional parity-time (PT) symmetry theory suggests that the strongest unidirectionality should occur exactly at the exceptional point (EP). We show that this expectation is generally incorrect, as the optimum is shifted away from the EP depending on the detuning from exact quasi-phase-matching resonance. We formulate a unified two-mode description for autonomous and driven systems, and derive the corresponding normal forms near the shifted singularities associated with the EPs.

Performing a global QCD analysis of data on the photon structure function $F_2^{\gamma}$ in $e^{+} e^{-}$ scattering, we determine new leading order (LO) and next-to-leading (NLO) parton distributions functions (PDFs) of the real photon. The resulting photon PDFs, referred to as VALO1.0, are obtained in the form of Monte Carlo (MC) replicas which assess the propagation of experimental uncertainties to the PDFs. To achieve well-converging fits, we employ a five-parameter hadron-like ansatz for the boundary conditions with simplifying assumptions on the flavor structure of the quark distributions and the large-$x$ behavior of the gluon distribution. This results in robust quark distributions at both LO and NLO and the gluon distribution at NLO with modest uncertainties, while leaving LO gluons still largely unconstrained. The resulting photon PDFs broadly agree with the parameterizations available in the literature and set the stage for future analyses including additional photoproduction data, which could help to increase the flexibility of our input PDFs. The LO and NLO VALO1.0 photon-PDF replicas, both in the DIS$_{\gamma}$ and $\overline{\rm MS}$ factorization schemes as well as the open-source $\gamma\texttt{EKO}$ code for solving the scale dependence of photon PDFs and the analysis framework $\texttt{VALOfitter}$ are made publicly available.

In classical settings, the Mpemba effect occurs when a hotter system cools faster than an initially colder one. In quantum systems, this effect can be reinterpreted exploiting the concept of symmetries, with the asymmetry of a subsystem playing the role of temperature. A quantum Mpemba effect arises when a more asymmetric state restores the symmetry faster than a less asymmetric one. Previous work mainly focuses on closed systems characterized by thermal equilibration and Hamiltonian symmetries. In this paper, we analyze the dynamics of asymmetry in an open quantum many-body system featuring symmetry breaking and uncover dynamical behavior that appears to be unique to these settings. In the symmetric phase, we demonstrate the existence of a quantum Mpemba effect, which emerges as a direct consequence of a non-monotonic evolution of the asymmetry. In the broken-symmetry phase, we analyze the imbalance between the system's ability to increase or to decrease its asymmetry. Our results extend the notion of quantum Mpemba effects to open quantum many-body systems exhibiting symmetry-breaking phase transitions and establish them as a platform for observing and controlling anomalous relaxation phenomena.

We present a first-principles investigation of the electronic structure, lattice dynamics, electron-phonon coupling, and superconducting properties of the hexagonal kagome-lattice compound Re$_2$Zr, in which time-reversal symmetry breaking and unconventional pairing have recently been proposed. We examine whether superconductivity in Re$_2$Zr can be explained within a conventional phonon-mediated framework by performing fully ab initio calculations within the density functional theory for superconductors. The electronic structure is characterized by a mixture of seven two- and three-dimensional Fermi surface sheets, giving rise to multiband superconductivity with many overlapping superconducting gaps. A spin-orbit-induced van Hove singularity is identified in the density of states near $E_F$. The electron-phonon interaction is moderately strong, with a coupling constant $\lambda \simeq 0.88$. Superconducting gap calculations reveal significant anisotropy and a broad distribution of gap values across different Fermi surface sheets. Spin fluctuations introduce additional depairing effects and reduce the critical temperature from 7.7 K to 6.4 K, in excellent agreement with the experimental value of 6.65 K. Taken together, our results show that the superconducting energy scale in Re$_2$Zr can be quantitatively reproduced within a conventional phonon-mediated framework, while the resulting state exhibits pronounced multiband and anisotropic gap structure. The origin of the experimentally suggested time-reversal symmetry breaking, however, remains an open question.

The chequerboard $J-Q$ model was proposed to describe the direct phase transition from the antiferromagnetic (AFM) state to the plaquette-sin glet (PS) solid state observed in SrCu$_2({\rm BO}_3)_2$. In this paper, we present a Monte Carlo study of the ground state of an extended ve rsion of this model. For all parameters investigated, we find only a direct first-order phase transitions from the AFM to the PS phase, with no intermediate phase between them. On the transition line, the system exhibits an emergent $O(4)$ symmetry. Furthermore, we find that the Bi nder ratio of the columnar valence-bond solid state can be used to locate the phase transition. It exhibits a monotonic finite-size scaling b ehavior, allowing for a precise determination of the transition point.

Lunar impact flashes provide a direct means of estimating the flux of centimetre-sized meteoroids impacting the lunar surface. However, 25-60 frames per second imaging typical of most monitoring programs limit the ability to resolve the rapid temporal evolution of the impact process, while the integration of Earthshine background restricts the detection of faint flashes. In this work, we present high-speed observations of lunar impact flashes captured at 200 and 250 FPS using the Zadko Telescope in Western Australia. We resolve the light curves of four confirmed events, revealing complex morphologies, some of which are not well modelled by simple exponential decays. One event was simultaneously detected by a second observer using a 50 FPS system, revealing a significantly faster brightness drop in the high-speed data that cannot be explained by spectral differences alone, indicating temporal integration of the vapour plume and subsequent ejecta. Our data also indicates that the initial flash intensity (representing the vapour plume) exhibits significantly less variance across events than the total luminous energy. Furthermore, we found no statistical correlation between the initial luminous energy and the total integrated energy of the flashes in this data, suggesting that the physical mechanism driving the initial vapour expansion may be physically decoupled from the longer-duration glow driven by the cooling ejecta. High temporal resolution combined with high sensitivity are therefore essential for accurately characterising the physical properties of the impactor and distinguishing the initial vapour plume from the subsequent incandescent cooling phase, although a significantly larger dataset is required to definitively constrain these mechanisms.

Several studies of black hole ringdown from particles plunging into black holes have identified contributions decaying at integer multiples of the surface gravity, called redshift modes, horizon modes, and direct waves. We show that, for Schwarzschild black holes, every one of these contributions has vanishing amplitude in the observable waveform. The cancellation follows from causality, which forces the source-integrated Green function to vanish on the light cone. Individual quasi-normal mode overtones still carry non-zero redshift-mode contributions, but these cancel exactly once the sum over overtones is performed; the so-called impulsive contribution to the waveform acts precisely as the counterterm enforcing this cancellation. Finally, we provide a motivation to the standard regularization of quasinormal mode excitation coefficients since divergences give rise to vanishing redshift modes.