Papers

We evaluate quantum electrodynamics (QED) nuclear medium effects under experimental conditions at the future Electron-ion collider in China (EicC). We consider neutral-current and charged-current elastic scattering, as well as neutral-current and charged-current deep inelastic scattering. We compute cross-section corrections at first order in the opacity expansion and estimate kinematic modifications due to multiple rescattering within the nucleus. We perform the first calculations of charged-current deep inelastic scattering and polarized scattering. We present results for the anticipated $^{197}_{79}\mathrm{Au},~^{208}_{82}\mathrm{Pb},$ and $^{238}_{92}\mathrm{U}$ nuclei and extrapolate these calculations to the lighter $^{40}_{20}\mathrm{Ca}$ isotope. We find that QED nuclear medium effects are non-negligible when extracting the process-independent non-perturbative structure of nucleons and nuclei at the EicC.

A central goal of optical computing is to perform calculations on the timescale of light propagation. Yet many analog photonic solvers require feedback, storage or field build-up before the answer becomes available, introducing additional latency that limits real-time operation. Here we introduce the concept of two-time modulation for temporal analog computing, in which the material response is independently modulated along two temporal directions, allowing the computational operator to be constructed continuously as the waveform propagates. The solution can therefore form during optical transit, without an additional solution-formation timescale. This form of temporal control allows identical copies of a waveform separated only in time to reach entirely different target outputs within a single spatial channel, and enables nonlocal integral-equation solving in a single passage. The resulting framework brings compact, programmable, real-time analog computation within reach for ultrafast optical information processing.

We develop a covariant framework for Josephson transport, superconducting interference, and shunt noise in the scale-dependent exterior generated by an Oppenheimer–Snyder-like collapse. Static Josephson frequencies and transported currents referred to Killing time acquire one lapse factor, whereas power acquires two. For a junction comoving with the collapsing surface, the coordinate-time phase rate differs from the frequency received at infinity because of null propagation and Doppler effects. We derive the exact radial-null travel-time kernel and show that its local near-extremal logarithmic enhancement crosses over, at fixed emission offset, to pole-controlled extremal behavior. We also obtain the redshifted resistively and capacitively shunted-junction equation and the dc and microwave-driven two-junction interference envelopes. In the negligible-total-inductance limit, static lapse imbalance modifies lobe amplitudes without shifting their centers, whereas microwave-induced translations require dynamical fluxoid closure. In a Hartle–Hawking state, Tolman redshift produces a superconducting exclusion layer and a lapse-independent asymptotic shunt-noise spectrum; its low-frequency limit obeys a parameter-free fluctuation–delay relation. Finally, we derive a shadow–Josephson consistency relation and sensitivity bounds on the running parameter.

In quantum metrology, adaptive and causal-superposition strategies are proven to be beneficial over parallel schemes for a finite number of channel uses, but their advantages disappear in the asymptotic limit. We show that quantum operations with indefinite time direction, specifically, time-flip (TF)-assisted strategies, referred to as indefinite time-directed metrology (ITDM), can overcome this asymptotic equivalence. Using semidefinite programming, we rigorously demonstrate that TF-assisted protocols can achieve quantum Fisher information (QFI) strictly exceeding the maximum value attainable by parallel, adaptive, and causal-superposition strategies, both for finite and asymptotically many channel uses. Moreover, we identify a class of Pauli noise channels for which ITDM achieves Heisenberg scaling, while all parallel, adaptive, and causal-superposition strategies remain restricted to standard scaling. We call this phenomenon as metrological activation. Interestingly, this activation can be used to exhibit that the quantum time-flip and transposition supermaps cannot be simulated by conventional quantum circuits or causal-superposition strategies using any finite number of channel queries, thereby establishing indefinite time direction as a genuine resource for quantum metrology.

Broadband optical colors have long been recognized as tracers of the surface spectral properties of trans-Neptunian objects (TNOs), yet their relationship to near-infrared (NIR) spectra has not been quantitatively characterized. We construct an empirical optical-NIR spectral manifold from JWST spectroscopy of 40 TNOs and 8 Neptune Trojans and interpret broadband photometry as compressed representations of this manifold. Using the spectral manifold as a prior, the model conditions on observed broadband optical colors to infer a posterior distribution in the spectral latent space. We then evaluate filter combinations through posterior entropy and Kullback-Leibler information gain and found that the gr colors provide broad localization on the manifold, while additional filters substantially reduce posterior uncertainty. Independently defined optical color populations map coherently onto the major compositional classes of the spectral manifold, providing a physical interpretation of previously identified color groups. The learned manifold also enables the inverse mapping back to optical color space. Sampling and decoding the manifold reproduces the observed topology of optical color space, indicating that these color populations arise naturally as low-dimensional projections of a continuous optical-NIR compositional manifold rather than isolated empirical clusters. The forward and inverse mappings provide a unified interpretation of optical colors as compressed representations of an optical-NIR spectral manifold. As JWST expands the manifold and Rubin maps millions of objects onto it, this framework provides an innovated approach to population-scale compositional studies and the discovery of rare surface types.

We study the production of $c$ and $b$ quarks in photon-induced processes as a probe of gluon saturation, with a focus on the high-energy region accessible in ultra-peripheral collisions (UPCs) at the LHC. We compare predictions for inclusive and diffractive heavy quark production with and without saturation effects by using the nonlinear Balitsky–Kovchegov and the linear Balitsky–Fadin–Kuraev–Lipatov equations for the evolution of the dipole amplitude. The percentage of coherent diffractive events is predicted to be $~20\%$ in the saturation model, which is approximately twice as large as predictions based on parton distribution functions and shadowing. This indicates that measurements of diffractive heavy quark production in UPCs may provide a sensitive probe for distinguishing linear and nonlinear regimes of quantum chromodynamics.

Sulphur(S)-bearing species are ubiquitous in Galactic star-forming regions, from dense cold cores to outflows and shocks linked to protostellar activity. A recent observational study investigated the origin of S-bearing species towards the central molecular zone (CMZ) of NGC 253 and showed that Sulphur emission is linked to the presence of forming stars. However, more extensive modelling of these observations are required to determine the exact origin of the Sulphur emission (e.g. shock or thermal evaporation). Using chemical modelling, we examine how S-bearing species behave in the more extreme environment of the starburst galaxy NGC 253, and more generally, how they can help us improve our understanding of the emission linked with the dense star-forming gas in external galaxies. We use the gas-grain time-dependent chemical model UCLCHEM to model static warm clouds and C-type shocks under the physical conditions found in the CMZ of NGC 253. We compare observed abundances and abundance ratios to the modelled output abundances. We found that depending on the model type (shock, post-shock or static cloud), the highest abundance reached by the S-bearing species varies significantly. Hence, we can use their observed abundances of S-bearing species to distinguish between shocked, post-shocked or a quiescent (non-shocked) gas. We also confirm observationally-based conclusions on their emission origins, including in the case of unresolved emission. Comparing GMC-scale observations with chemical modelling is a powerful method to investigate and constrain the origin of molecular emission towards extragalactic star-forming regions. Sulphur-bearing species are useful to distinguish between different types of ISM components (shocked/post-shocked/quiescent gas).

Topological valley kink states (VKSs), which are quantum valley Hall states emerging at the interfaces between adjacent domains with opposite valley Chern numbers, have attracted considerable interest in graphene-based systems. In this work, we investigate the quantum transport of VKSs in ABC-stacked rhombohedral multilayer graphene in the presence of Anderson disorder and a perpendicular magnetic field. Two prominent transport characteristics are revealed. First, in the absence of a magnetic field, the kink states exhibit strong layer polarization, with their wave functions predominantly localized and equally distributed on the outermost top and bottom layers. As a result, their transport properties are highly sensitive to the layer-selective disorder distribution. Second, under a perpendicular magnetic field, the layer-symmetric spatial distribution of VKSs is broken, leading to a significant reduction in the wave-function overlap between counter-propagating VKSs from opposite valleys. Consequently, intervalley scattering is suppressed, and the transmission of VKSs through disordered regions is substantially enhanced. Our results provide new insights into multichannel topological valley transport in rhombohedral multilayer graphene and demonstrates disorder-engineering and magnetic fields as effective approaches for manipulating the propagation of VKSs.

We study linear instabilities and pattern formation in a spatially extended Selkov model for glycolysis with diffusion and chemotactic interactions between two species. Linear stability analysis reveals two distinct bifurcations: a zero-wavevector, finite-frequency Hopf bifurcation leading to spatially homogeneous oscillations, and a finite-wavevector Turing instability with a saddle-node bifurcation leading to stationary inhomogeneous patterns. The selected wavevector, $k_c$, depends sensitively on the nature and strength of chemotaxis and varies nonmonotonically with the chemotaxis parameters, allowing re-entrant transitions between homogeneous and patterned states. For sufficiently strong chemotaxis, when the two species mutually attract or mutually repel each other, an unusual instability emerges in which the preferred wavevector diverges as a finite threshold in chemotactic strength is approached. We complement the linear analysis with extensive direct numerical simulations (DNS) of the nonlinear partial differential equations in two dimensions. The DNS confirm the predicted instabilities and their nonmonotonic and re-entrant character, and also reveal spatially uniform oscillatory states for suitable parameters. The stationary patterns include spots and, unexpectedly, stable stripes. We further uncover transitions between spot and stripe morphologies controlled by chemotactic strength and diffusivity ratios. The stability of the striped states is consistent with linear amplitude equations, whereas the spot-stripe transition is attributed to nonlinear effects beyond linear stability. Our results demonstrate that chemotaxis can act as a nonmonotonic control parameter for instability selection, wavelength selection, re-entrant pattern formation, and nonlinear pattern morphology in reaction-diffusion systems.

We formulate an energy-consistent quantum-optical representation of finite paraxial laser pulses in free space. The formulation is based on a continuous-mode description and provides a step toward a unified treatment of coherent and nonclassical strong-field drivers. Starting from plane-wave quantization, we construct a transverse vector-mode reduction in which the selected mode can reproduce an arbitrary normalized spatial–polarization profile. For a coherent pulse, the measured pulse energy and full laboratory analytic signal determine the frequency-dependent coherent-state displacement $(\alpha(\omega))$, without introducing a physical quantization volume. For nonclassical pulses, the same first-order field data and total energy do not uniquely specify the quantum state. Additional correlation information or model assumptions are required. We incorporate this information through normal and anomalous covariance kernels and discuss $g^{(2)}$-based diagnostics of squeezed pulses. We also derive a phase-sensitive convergence criterion for numerical frequency-bin discretizations. An exactly solvable continuum-mode free-electron application shows that the coherent displacement reproduces the semiclassical mean trajectory, whereas the field covariances determine the electron wave packet width. The framework offers a convenient, energy-consistent interface between measured free-space pulses and quantum-optical calculations.

This paper presents a conceptual model exploring how liquid water could be maintained in direct contact with hypothetical microorganisms during warm daytime periods on Mars. Hygroscopic surface salts (e.g., NaCl, CaCl$_2$, Ca(ClO$_4$)$_2$, gypsum, MgSO$_4$) can absorb water vapor and form liquid solutions; however, daytime exposure normally causes rapid drying. We propose a mechanism where diurnal temperature fluctuations drive thermal expansion and contraction cycles that open and close micro-cracks in salt crystals. Nighttime-condensed deliquescent liquid penetrates these fractures, which then partially close during warmer daytime hours, trapping liquid water inside and preventing immediate evaporation. Thermally induced volume changes (ranging from ~0.5-0.9% in crystalline phases up to several percent in concentrated solutions) support the feasibility of this cyclic aperture dynamic. Modeling deliquescence and salt distribution indicates that nighttime microscopic liquid can form for ~100-130 sols per Martian year near Acidalia Planitia. At depths of 2-3 mm within soil or salt structures, hypothetical microorganisms would gain partial UV shielding while retaining access to visible light. Overall, internal crystal micro-fractures may offer transient daytime liquid microenvironments, highlighting these locations as potential candidate habitats for photosynthetic life on modern Mars.This study serves as a conceptual feasibility analysis for near-surface brine retention within hygroscopic salt structures under present-day Martian conditions.

We address the existence and dynamics of solitons propagating along helical (spiral-rotating) and straight trajectories in the bulk waveguide with the cubic-quintic nonlinearity and a single- or multi-ring potential. The input is taken as a vortex beam with a single or multiple phase singularities (pivots), displaced from the waveguide's axis. The single off-axis pivot creates a one-ring helical soliton, with a closed or open (split) ring structure. The vortex beams with multiple off-center pivots give rise to complex states with multi-ring, multi-core, and/or multi-split structures. The multi-core/split solitons propagate along helical channels, or straight ones, which are parallel to the propagation axis. The sign and period of the helicity can be precisely adjusted by applying a torque with an appropriate angular velocity.

An important property of the quasi-spherical Szekeres cosmological model appears to be widely misunderstood in the literature. In this paper, the claim that the matter density can be fully decomposed on a given 2-shell into a dipole superposed on a monopole is shown to be inaccurate and exact propositions are substituted. Then, the multipole decompositions of three different quantities linked to the mass density are displayed and proposed to constrain the Szekeres parameters with observed data. A test of the axial symmetry assumption, together with that of an on-axis observer, using a property of the angular coefficients is also suggested.

Future pulsar timing observations near Sgr~A* offer a unique probe of gravitational physics in the vicinity of a supermassive black hole. We forecast the ability of such measurements to constrain a Buchdahl-inspired $R^2$ gravity, parameterized by a single deviation parameter $\epsilon$, using a timing framework that self-consistently integrates orbital dynamics with light-propagation delays and preserves the full timing solution across the observing span. Through Fisher-matrix forecasts for a representative pulsar, we systematically isolate how the precision on $\epsilon$ depends on orbital geometry. We find that shorter orbital periods and higher eccentricities significantly enhance sensitivity, consistent with a substantial contribution from observations near periastron. As a benchmark comparison, we further consider a hypothetical pulsar on an S2-like orbit ($P_b=16~{\rm yr}$, $e=0.88$) and obtain a statistical sensitivity of $\sigma_\epsilon\sim 10^{-4}$ within the adopted weak-field, static, and spherically symmetric timing model. This sensitivity is comparable to the natural order-of-magnitude truncation scale of the 1PN expansion and should not be interpreted as a complete forecast for the real Sgr~A* system. Under the adopted idealized assumptions, the characteristic statistical scale is several orders of magnitude below the current S2 95% confidence interval half-width ($|\epsilon|_{\rm S2}^{\rm 95\%}\approx 0.56$), though this comparison is heuristic given the differing confidence levels. These trends provide quantitative guidance for target selection and campaign design in future Galactic-center pulsar searches.

Massive, star-forming clumps are regions of intensive star-formation that are commonly observed in high-redshift ($z > 1$) galaxies. Observations of low-redshift clumpy galaxy analogues are rare but the availability of wide-field galaxy survey data makes the detection of large clumpy galaxy samples much more feasible. We present a population of 12,790 star-forming clumps detected in a mass-complete sample of 5,395 star-forming galaxies (SFGs) at redshifts $z\leq0.32$, located in the XMM-LSS, E-COSMOS and DEEP2-3 fields observed by the Hyper Suprime-Cam Subaru Strategic Survey (HSC-SSP) and CFHT Large Area U-band Deep Survey (CLAUDS). The clumps were detected using an improved version of our Deep Learning (DL)-based object detection framework which uses the ZOOBOT foundation DL-model as a 'backbone' feature extractor. We determined the fraction of star-forming galaxies hosting at least one off-centre clump ($f_{\mathrm{clumpy}}$) based on a clump definition that requires a clump-galaxy flux ratio in the CLAUDS u-band of $\geq8\%$. We estimate $f_{\mathrm{clumpy}}$ to decrease from $\sim$31% at $z\sim0.3$ to $\sim$23% at $z \sim 0.1$, which aligns well with a low-redshift extrapolation of the clumpy fraction that is measured using high-redshift observations. At fixed redshift, $f_{\mathrm{clumpy}}$ is negatively correlated with the stellar mass and positively correlated with the specific star-formation rate (sSFR) of the host galaxies. When the clump definition is changed to include only clumps with a stellar mass of $M_{\mathrm{cl}} \geq 10^7 M_\odot$, we observe a highly increased clumpy fraction of $\sim$60% that tends to increase with the stellar mass of the host galaxies but does not show a dependence on the sSFR of the host galaxies.

Interlayer excitons in transition-metal dichalcogenide heterobilayers possess intrinsic out-of-plane dipole moments, providing a platform for investigating exciton-exciton interactions at high densities. Here, we use excitation-energy-dependent photoluminescence excitation (PLE) spectroscopy to probe the nonlinear response of dipolar interlayer excitons in chemical vapor deposition-grown MoSe$_2$/WSe$_2$ heterobilayers. By tuning the excitation energy across intralayer exciton resonances at fixed excitation power, we selectively vary the population injected into the interlayer exciton states. Resonant excitation drives the system into a nonlinear regime, leading to saturation of the interlayer exciton photoluminescence and an apparent broadening of the intralayer $1s$ resonances in the PLE spectra. At the same time, the interlayer exciton emission exhibits a pronounced blueshift, reaching approximately 2.5 meV at 4 K and 1 meV at 75 K. The blueshift increases systematically with the interlayer exciton population and is consistent with a net repulsive exciton-exciton interaction, with contributions from dipole-dipole repulsion in the density regime investigated. Our results establish PLE as a sensitive approach for accessing the nonlinear, high-density regime of interlayer excitons and probing their interactions in van der Waals heterostructures.

Optomechanical membrane-in-the-middle systems that comprise several coupled compliant membranes offer enhanced optomechanical coupling and collective dynamics. Recent realizations were fundamentally restricted to two membranes and to limited structural optimization of the involved membranes due to their intricate fabrication and experimental integration. Here, we present a fiber-based Fabry-Perot microcavity incorporating monolithically integrated double-membrane resonators fabricated by 3D direct laser writing. We realize controllable mechanical mode hybridization of membranes with coupling rates of up to $J_{\mathrm{mech}}/2\pi = 0.16$ MHz, exceeding the mechanical linewidths. We demonstrate enhanced collective optomechanical coupling of the membrane stack's breathing mode, reaching collective coupling strengths of up to $g_{\mathrm{col}}^{(-)}/2\pi \approx 0.1$ MHz. Our transfer-matrix calculations predict further substantial enhancements with realistic reductions of membrane thickness and spacing, and a larger number of membranes. Our results establish direct laser-written membrane arrays as a scalable platform for multimode cavity optomechanics, combining tunable mechanical interactions, enhanced collective optomechanical coupling, and scalability towards larger mechanically coupled resonator systems.

Let A denote the infinite Gram matrix associated with the standard L2 inner product of asymmetrically-weighted (AW) Hermite functions. We derive an explicit representation of its entries and its Cholesky factorization. We further show that this factorization admits a natural interpretation on a scaled Bargmann-Fock basis. An explicit formula for the inverse of A is also obtained. We then consider the corresponding finite Gram matrix and analyze its asymptotic property, as well as that of its Schur complement. The analysis is motivated by numerical methods for plasma physics, in particular Galerkin spectral methods applied to the Vlasov-Poisson (VP) system. As an application, we demonstrate how the derived Gram matrix formulas and asymptotic results can be exploited in the analysis and implementation of a Galerkin spectral method for the VP system.

We numerically demonstrate an asymmetric corner-reflector uni-traveling-carrier waveguide photodiode (UTC-WGPD) that simultaneously suppresses optical back-reflection and breaks the bandwidth-responsivity trade-off. Off-center beam coupling introduces geometric asymmetry to eliminate retroreflection while maintaining efficient light trapping. 3D optoelectronic simulations reveal that at 1550 nm, a 15-{\mu}m^2 device exhibits a 275-GHz 3-dB bandwidth, 0.68-A/W responsivity (54.5% quantum efficiency), and -29-dB back-reflection, achieving a 150-GHz bandwidth-efficiency product. This design offers a scalable, low-reflection detection scheme for sub-terahertz transceivers and dense photonic integration.

Particles with magnetic moment can be polarized, and rapidly rotated, employing a magnetic field such that the dipolar interaction among them changes sign, becoming antidipolar and thus isotropically attractive in a plane. Polar molecules can also be manipulated using microwave dressing fields to invert the sign of the dipole-dipole interaction. In this work, we study a two-dimensional system of antidipolar particles by calculating its equation of state and structural properties. The system behaves as a liquid even for scattering lengths significantly greater than the dipolar length. For large enough densities, the system transitions to a solid with one particle per lattice site via a first-order phase transition at a significantly smaller density than its dipolar counterpart. Moreover, motivated by the recent realization of a strongly axially trapped, bilayer geometry [Science 384, 546-551 (2024)], we study the properties of the bilayer liquid phase as the inter-layer distance is tuned, and provide the range of parameters where one layer can influence the properties of the other.

We show that the relative phase primarily controls the survival, rather than the initial formation, of the common bridge in head-on collisions of radially excited boson stars. In the benchmark configuration, all sampled phases form both a common and a strong bridge. After aligning the evolutions at the same operational weak-contact level, their early post-contact evolution remains similar, while a clear phase hierarchy develops only later, with larger phase offsets producing a weaker and less persistent connection. The same suppression persists under controlled variations of the central scalar amplitude, quartic self-interaction strength, and scalar potential. These results identify relative phase as a control on the nonlinear persistence of the common bridge rather than simply on the instantaneous scalar-field overlap.

Electro-optic frequency conversion and synthetic-frequency coupling are established functions in integrated photonic devices. Their role within a multiport switching fabric, however, depends on how simultaneous optical connections share spatial paths, frequency channels, and device controls. Here, we investigate how coherent coupling among frequency modes can be incorporated into photonic switching fabrics and identify the corresponding architectural and physical constraints. We show that synthetic-frequency coupling does not increase the number of simultaneous orthogonal frequency channels when all channels are freely accessible, but can establish connections that are otherwise blocked by fixed input frequencies, channel-continuity requirements, or unavailable output channels. Under the tested conditions, coupling over the first three frequency spacings in an $8\times8$ fabric with eight frequency channels per port achieves 96.1% of the blocking reduction obtained with unrestricted inter-mode coupling. We further show that a separate frequency-only conversion stage cannot replace missing spatial connectivity. A nominal reduction in spatial switching elements instead requires a joint element whose spatial state can be programmed independently for each frequency channel. Finally, we evaluate a thin-film lithium niobate resonator model using reported electro-optic coupling and photon-decay scales within a multistage Mach-Zehnder interferometer switching fabric. These results clarify the architectural role of synthetic-frequency coupling and the device-level requirements for incorporating it into integrated photonic switching fabrics.

We investigate pattern formation in generic two-species reaction-diffusion systems with mutual chemotaxis. We show that tuning the chemotaxis strength can give rise to striking nonmonotonic variation of patterns, opening the possibility of re-entrant transitions between patterned and spatially uniform steady states. In certain regimes, chemotaxis also induces additional heretofore unexplored instabilities. Furthermore, varying the strength of chemotaxis can drive morphological transitions between spot and stripe patterns.

The 21 cm hyperfine transition of neutral hydrogen provides one of the few direct probes of the early cosmic history. High-redshift detections of this signal could shine light on the poorly understood epochs of the Dark Ages and Cosmic Dawn, periods that remain among the least understood in the Universe's history. However, this signal is masked by bright foregrounds and is distorted by the chromaticity of the antenna used to detect it. Correcting for the chromaticity requires an accurate representation of the radio sky across relevant frequencies. However, base sky maps used for this correction, such as instances of the Global Sky Model (GSM), are limited by resolution, calibration and extrapolation uncertainties, especially when scaled to lower frequencies relevant for Cosmic Dawn studies. This work quantifies how accurately the base map must represent the true sky to produce a reliable beam correction. Using simulated sky data, we generate beam chromaticity corrections generated from progressively degraded versions of the base map, and compare how well they do in comparison to a correction based on the full-resolution map. We find that degradation in map resolution of $\sim 1^\circ$ does not introduce measurable increases in the amplitude of the residuals when correcting for the chromaticity and subtracting three different foreground models (two polynomials and a power law expansion). These results provide practical constraints on the required resolution and accuracy of sky models used in beam correction pipelines, informing future design and calibration strategies for global 21 cm experiments, and future efforts to map the low frequency sky.

We report a cryogen-free cryogenic current comparator (CCC) system for precision resistance measurements. A helium-gas chamber was developed and installed on the 4 K stage of a cryogen-free dilution refrigerator equipped with a pulse-tube cryocooler. The CCC probe was housed in this chamber and was cooled through helium gas serving as a heat exchange medium. The metrological performance of this helium-gas-cooled CCC was evaluated through precision resistance-ratio measurements and found to be comparable to that obtained under liquid-helium cooling. A quantum Hall resistance (QHR) device was also integrated into the same refrigerator, enabling QHR/100~$\Omega$ resistance-ratio measurements. The type-A uncertainty reached the 1~n$\Omega$/$\Omega$ level within an averaging time of 100~s, and the resulting resistance-ratio measurements agreed well with conventional liquid-helium-based measurements at the level of a few n$\Omega$/$\Omega$. The system provides this level of measurement performance while consuming less than 1~L of helium gas per thermal cycle.

Mass loss in low-mass stars during the red giant branch (RGB) and early asymptotic giant branch (EAGB) phases plays a key role in shaping stellar evolution, yet its dependence on stellar parameters such as metallicity remains poorly constrained, with observational studies yielding conflicting trends. We present the first asteroseismic analysis of RGB and EAGB stars in NGC 5897, the most distant and metal-poor globular cluster observed by the Kepler space telescope during the K2 mission. We detected solar-like oscillations and derived the frequency of maximum power excess, $\nu_{\rm max}$, for 20 RGB and 6 EAGB stars. Using asteroseismic scaling relations, we derived mean masses of $\overline{M}_{\rm RGB} = 0.74\pm0.01\,M_{\odot}$ and $\overline{M}_{\rm EAGB}=0.65\pm 0.03\,M_{\odot}$. The inferred integrated mass loss between the two phases is $\Delta M_{\rm RGB-EAGB}=0.08\pm 0.03 \,M_{\odot}$. We present an updated mass-loss–metallicity relation for Type I globular clusters, extending it to the very metal-poor regime and supporting decreasing integrated RGB mass loss with decreasing metallicity.

Exchange-dominated magnons in nanometer-thick ferromagnets extend to the terahertz regime through thickness quantization of perpendicular standing spin-wave (PSSW) modes. While interfacial spin-orbit torques (SOTs) have been shown to enable the excitation of such modes, the microscopic origin of the interfacial driving torque remains unclear. In particular, the coexistence of spin and orbital currents complicates the understanding. Here, we develop and use an atomistic framework that explicitly resolves interfacial symmetries and separates spin and orbital torque contributions. Exploiting a trilayer geometry for a thin ferromagnet sandwiched between non-magnetic layers, where the symmetry-controlled polarity of the interfacial torque produces mode-selective magnon excitation as observed in the recent experiment of Salikhov et al. Nature Phys. 19, 529 (2023), we disentangle the different interfacial torque contributions. By decomposing the torque into magnetization-even (field-like) and magnetization-odd components, we identify the field-like torque as the dominant contribution responsible for the excitation. Crucially, isolating orbital and spin contributions reveals that the interfacial orbital torque provides the primary channel for the efficient excitation of exchange-dominated THz magnons in thin ferromagnets. Our results establish a microscopic basis for symmetry-engineered control of confined terahertz spin dynamics in magnetic multilayers.

X-ray timing information produced through Fourier analysis from the variable emission of black hole X-ray binaries has been used for several decades to provide key insights into the physical setup of these systems not measurable with spectroscopy. In particular, quasi-periodic oscillations within these systems have been of particular interest and remain the source of great debate on how they come about. We investigate the timing products of simple toy models of QPO variability to provide more intuition when thinking about signals produced by these sources. We simulate simple physical setups and show how phase lags and coherence of the signals change in these different setups. We first focus on properties of QPO like signals under a single driving signal assumption. We then investigate the case of multiple oscillations in a signal. Finally, we investigate how timing products change when QPOs are produced by time dependent modulation of periodic signals. Many simple physical setups with common driving signals are able to reproduce complex non-linear phase lags that resemble those present in the data. The changes in physical setup aligns with experience in the data, such as differing power spectra but fall short of reproducing the data as expected. Multiple incoherent processes present in the signal struggle to reproduce behaviour present in the data. Coherence seems to be a more useful tool for differentiating between setups. Fourier analysis with complicated data like that produced by X-ray binaries can lead one to be tempted to invoke exotic lag mechanisms without the appropriate framing. This paper attempts to help provide tools and intuition as to how different phenomena in signals (particularly relating to QPOs) can result in non-linear phase lags with explicit structure.

We construct Galilean limits of the free Kalb–Ramond two-form gauge field and analyze their symmetries using two different procedures. An Inönü–Wigner contraction of the $D$-dimensional equations of motion results in two inequivalent electric and magnetic limits. In both cases the equations are invariant under the complete infinite-dimensional Galilean conformal algebra (GCA) only at $D=6$, the critical dimension of the relativistic theory. The second procedure is a null reduction of the $(D+1)$-dimensional theory which yields a local action for a four-field multiplet. In the zero-momentum sector, the resulting action is invariant under translations, rotations, Galilean boosts and an anisotropic dilatation with dynamical exponent $z$. However, in contrast to Galilean electrodynamics, it is not invariant under the special conformal generators of the GCA (and its higher modes). We attribute this to the vector residing at the bottom of the boost chain. If the parent theory is taken to be the six-dimensional conformal one, the resulting five-dimensional reduced action is invariant under the Schrödinger special conformal transformation with $z=2$ which is derived from the relativistic conformal group. In light-cone gauge, the non-zero null momentum sectors reduce to free Schrödinger fields. We obtain the gauge-fixed propagator, which is instantaneous, and compare the free-field correlators with the two-point functions allowed by the Ward identities of both.

Extracting physics information from modern particle-physics experiments requires multistage analyses implemented on top of large and highly interconnected software ecosystems. General-purpose large language models (LLMs) often produce unreliable programs for such tasks because a user request alone rarely specifies the required APIs, dependencies, and usage conventions. We organize these software relations before generation and retrieve task-relevant knowledge at inference time. Using the open-source ROOT framework as a representative and reproducible testbed, we evaluate a complete grounding system that combines hybrid retrieval over a heterogeneous software knowledge graph, skill-selected workflow examples, and execution-guided repair. On a benchmark of 275 ROOT tasks, grounding improves first-attempt execution from 58.5% to 76.0% under Claude Code orchestration and from 51.3% to 64.0% under standalone orchestration. Final success increases from 90.5% to 96.0% and from 78.9% to 90.9%, respectively, while the average generation cost per successful task increases by only 1.3% and 3.2%. The gains persist under a strong coding agent, indicating that explicit software knowledge remains valuable even when agentic scaffolding is already in place. Because the method captures software relations common to large codebases rather than facts specific to ROOT or a particular model, it should transfer to other experiment frameworks and proprietary software, especially where documentation is sparse or internal dependencies are complex.