arXiv subjects

Z. Li

Publications and source records attributed to Z. Li.

At least 19 recordsLinked to original sources

arXiv2026

Constraining reionization-era Ly$\alpha$ escape with JELS-MUSE: a highly complete H$\alpha$-selected sample at $z\sim6.1$

The Ly$\alpha$ escape fraction, $f_{\rm{esc}}^{\rm{Ly}\alpha}$, probes both the interstellar medium (ISM) conditions governing ionizing photon escape and the rising neutral fraction of the IGM through the Epoch of Reionization (EoR). Characterising the intrinsic, ISM-driven distribution of $f_{\rm{esc}}^{\rm{Ly}\alpha}$ before IGM attenuation becomes dominant is essential to interpret the observed decline in Ly$\alpha$ visibility through the EoR. We present $f_{\rm{esc}}^{\rm{Ly}\alpha}$ measurements for a highly complete, H$\alpha$-flux-limited sample of 24 star-forming galaxies at $z \approx 6.1$, drawn from the JWST Emission Line Survey (JELS) and observed in Ly$\alpha$ with VLT/MUSE as part of the JELS-MUSE Large Area Survey. We detect Ly$\alpha$ in 12 of 24 sources and a Ly$\alpha$ emitter fraction of $X_{\rm{Ly}\alpha} = 33 \pm 12$ per cent using the canonical EW(Ly$\alpha$) $> 25 \, \mathring{\rm{A}}$ definition. Incorporating non-detections via reverse Kaplan-Meier survival analysis yields $\langle f_{\rm{esc}}^{\rm{Ly}\alpha} \rangle = 0.07^{+0.04}_{-0.03}$, consistent with an independent stacked-flux estimate of $0.08^{+0.02}_{-0.02}$. Using reionization simulations matched to the area, depth, and redshift range of our survey, we find that all galaxies are expected to experience broadly similar IGM transmission, so we postulate that the large scatter in $f_{\rm{esc}}^{\rm{Ly}\alpha}$ reflects genuine ISM-driven variance rather than differences in the surrounding IGM. Among the detections, higher $f_{\rm{esc}}^{\rm{Ly}\alpha}$ galaxies tend to have lower nebular dust attenuation, bluer UV slopes, and lower stellar mass, consistent with feedback-regulated escape through localised, low-column-density ISM channels around star-forming regions. These results benchmark intrinsic Ly$\alpha$ escape at the end of reionization, against which IGM suppression at $z > 7$ can be interpreted.

astro-ph.GA↗

arXiv2026

ELMO: An Uncertainty-Aware Simulation-to-Surrogate Workflow for Fast Pedestal Linear-Stability Prediction

Rapid prediction of pedestal linear stability is important for exploring tokamak operating space, uncertainty quantification, and future model-informed control, but mode-resolved magnetohydrodynamic stability calculations using BOUT++ are computationally expensive. We present a focused implementation of ELMO--the Edge Learning and Modeling Orchestrator--as an uncertainty-aware simulation-to-surrogate workflow integrating equilibrium generation, field-aligned mesh construction, large-scale BOUT++ calculations, automated campaign execution and data reduction, and Gaussian Process Regression (GPR). For a single DIII-D plasma shape, 3,869 of 7,992 requested configurations completed equilibrium reconstruction, mesh generation, stability calculation, and quality control. Each retained equilibrium was evaluated at sixteen toroidal mode numbers, $n=5$--80 with $\Delta n=5$, using ideal-MHD and ideal-plus-diamagnetic models, producing 123,808 mode-resolved calculations. Using eight pedestal features, the GPR surrogate predicts two sixteen-mode growth-rate spectra with latent posterior uncertainty estimates. Across five independent test realizations, the maximum-growth-rate prediction achieved $R^2=0.978\pm0.013$ for ideal MHD and $R^2=0.966\pm0.009$ for ideal-plus-diamagnetic physics. The surrogate reproduces the spectral shape and dominant unstable mode. Calibration diagnostics indicate that posterior uncertainties are useful for relative acquisition but are underdispersed and should not be interpreted as calibrated prediction intervals. Prediction of all 32 outputs requires about 20 ms on one CPU core, compared with about 21 min using 128 CPU cores for the corresponding BOUT++ scan, giving a $6.3\times10^4$-fold wall-clock speedup and an $8.1\times10^6$-fold reduction in computational cost.

physics.plasm-ph↗

arXiv2026

Affine Anosov Maps on $\mathbb{R}^n$: Classification, Index Spectrum, and Stability at Infinity

For $n\ge2$, we classify the affine diffeomorphisms $f_{A,v}(x)=Ax+v$ on $\mathbb R^n$ that admit a complete Riemannian metric with respect to which they are Anosov. Such a metric exists if and only if $A$ is hyperbolic or $f_{A,v}$ has no fixed point, equivalently $v\notin\operatorname{Im}(I-A)$. In the latter case, $f_{A,v}$ is smoothly conjugate to a translation when $\det A>0$ and to White's map times the identity when $\det A<0$. We also determine the possible stable indices. In the hyperbolic case, the index is determined by the stable spectrum of $A$, whereas a map with no fixed point admits complete Anosov metrics of every stable index from $1$ to $n-1$. Along the $1$-eigenspace, every such metric must exhibit exponential growth of vector norms along one of the two half orbits. We then determine the interior and boundary of the Anosov-realizable locus in the affine parameter space and describe the corresponding change of the index spectrum near regular drift parameters. Finally, we show that Anosov-realizability is not open in the two-sided weak $C^1_{\mathrm{loc}}$ topology but is open in the two-sided strong Whitney $C^1$ topology.

math.DS↗

arXiv2026

Dynamical control of particle jets from a driven condensate in a one-dimensional lattice with double-well potential

We investigate the nonlinear dynamics of a Bose-Einstein condensate trapped in a double-well potential of a one-dimensional lattice, where the interatomic interactions are periodically modulated in time. In the typical case of a symmetric double-well, we observe collective particle emission under resonant driving, where the excitation regimes are explicitly constrained by the interplay between the drive strength and the hopping amplitude. By introducing a depth asymmetry between the wells, we find that moderate bias specifically enhances the emission rate, while large asymmetry suppresses it. The particle jets can be further controlled by modulating the hopping amplitudes, where the emission is weakened for finite hopping imbalances. These results outline the roles of asymmetry and external driving in precisely manipulating quantum many-body transport, and may offer insights into the design of atomtronic devices.

cond-mat.quant-gas↗

arXiv2026

Efficiency measurements of GEM GE1/1 chambers in the upgraded CMS Endcap Muon System using 2023 collision data at $\sqrt{s}=13.6$ TeV

The CMS experiment at the Large Hadron Collider employs Gas Electron Multiplier (GEM) detectors, a technology based on gaseous ionization, as one of the muon detectors. The muon spectrometer is being upgraded to handle the increased muon flux in the forward region. This study analyzes muon detection efficiency in the GE1/1 triple-GEM detector, using 2023 proton-proton collision data at $\sqrt{s}=13.6$ TeV. A dataset enriched with muons from Z boson decay, with a total recorded luminosity of 17.8 fb$^{-1}$ has been used for this study. The detection efficiency of 137 GEM detectors are measured using muon trajectories established using other detectors in the tracking and muon systems, without use of the GEM detectors. The average efficiency of 137 GEM detectors is $\sim$93.3$\%$. A subset of 108 detectors that had no shorts were operated at the nominal HV working point with average efficiency of $\sim$96$\%$. Efficiency is found to be unaffected by the number of p-p interactions per bunch crossing (pile-up).

hep-ex↗

arXiv2026

A new model of quasar mass evolution

Magnetic monopoles have been a trending topic among physicists and astronomers since the 1930s. Researchers have been working hard to find evidence of magnetic monopoles in laboratories. The existence of magnetic monopoles can rationally explain the stability of charges, the quantization of charges, the structure of leptons, the unified composition of leptons and hadrons, and the symmetry of leptons and quarks. The presence of these mysterious particles in the universe could have significant implications for theoretical physics and astrophysics. The Grand Unified Theory has also predicted the existence of magnetic monopoles, which is interestingly implied by some astronomical observations. Noticing that the growth of supermassive black holes in the early universe is an increasingly challenging difficulty faced by astronomers, here we argue that it could be solved with the help of magnetic monopoles. As suggested by Peng et al. in A Monopole Model for Galactic Nuclei. In: Structure and Evolution of Active Galactic Nuclei, vol. 121, p. 663 (1986), quasars containing magnetic monopoles at the center can continuously catalyze the decay of protons to release energy. We examine this model by using quasar data from the Sloan digital sky survey. It is shown that the initial mass distribution of quasars derived from the magnetic monopole model exhibits a Gaussian distribution. At the same time, the initial mass function is also slightly higher than previously expected, which could be verified by future observations.

astro-ph.GA↗

arXiv2026

Early results from the SVOM Observatory Science program

We present the organisation and early results from the Observatory Science program of the Space-based multi-band astronomical Variable Objects Monitor (SVOM), based on data collected between July 2024 and December 2025. Although primarily designed for gamma-ray burst studies, SVOM's wide-field, multi-wavelength instruments enable a broad range of high-energy astrophysical investigations. We summarize the execution and performance of the General Program and Target-of-Opportunity observations, and we describe the frameworks used for serendipitous source detection and monitoring with the ECLAIRs coded-mask instrument. Over this period, SVOM carried out more than a thousand pointed observations and detected several hundred non-GRB high-energy sources, mainly X-ray binaries, as well as blazars, stellar flares, magnetars, and unidentified events. We highlight some key results, including the monitoring of the microquasar Cygnus X-1, the detection of burst oscillations from the Low-Mass X-ray Binary 4U 0614+091, the spectral-state monitoring of Aql X-1, the first SVOM detection of an X-ray blazar flare from 1ES 1959+650, and observations of a stellar flare from HD 22468. These results demonstrate SVOM's strong capabilities for time-domain astrophysics beyond its core GRB program.

astro-ph.HE↗

arXiv2026

Numerical Study of Compressibility and Velocity Parameter Effects on Spatially Evolving Supersonic Turbulent Shear Layers

Direct Numerical Simulations (DNS) of a spatially developing supersonic turbulent shear layer are conducted for a range of convective Mach numbers ($M_c$) and velocity parameters ($\lambda$) to examine the effects of compressibility and advection on the growth rate, self-similarity, flow statistics, asymmetry, and entrainment of the layer. At distant downstream locations, self-similarity is attained for all cases. The self-similar region is identified by the collapse of normalized mean streamwise velocity, the constant peak of normalized Reynolds stresses, and the linear growth rate of the shear layer thickness and momentum thickness. Despite significant variations in lower-order and higher-order statistics across different $M_c$ and $\lambda$ values, profiles of all turbulence quantities examined collapse within the self-similar region using our proposed self-similar scalings. The self-similar forms of continuity, momentum, and energy equations have been formulated, incorporating compressibility and centerline shifts. The self-similar normalized density distribution inside the layer is used to explain the effects of compressibility on various flow statistics, including the far-field cross-stream velocity. The density variation is linked to dissipation effects as revealed by our analysis of the self-similar energy equation. An approximate equation for the cross-stream velocity is developed, and the profiles of cross-stream velocity obtained from this equation show good agreement with the DNS results. A geometric interpretation of the entrainment ratio is presented, and the approximate equation for the cross-stream velocity is used to provide a general closed-form expression of the entrainment ratio. The entrainment ratio increases with $M_c$ and $\lambda$, favoring excess entrainment on the high-speed side.

physics.flu-dyn↗

arXiv2026

Search for Diffuse Supernova Neutrino Background in the Full KamLAND Dataset with Neural-Network-Based Event Classification

We report a search for the diffuse supernova neutrino background (DSNB) with the KamLAND detector, targeting electron antineutrinos via inverse beta decay in the neutrino energy range of 8.3 to 30.8 MeV. Using liquid-scintillator exposures of 9.02 kton-year for 8.3 to 9.3 MeV and 9.42 kton-year for 9.3 to 30.8 MeV, we observe seven candidate events after applying a new deep-neural-network-based event classification technique. This result is consistent with the background-only expectation of 16.2 plus or minus 9.4 events, including systematic uncertainties associated with the neural-network selection. A spectral analysis of the energy and radial distributions finds no significant excess attributable to the DSNB. We therefore set 90 percent confidence-level upper limits on the DSNB flux of 38 to 43 per square centimeter per second, depending on the assumed DSNB model. We also derive model-independent 90 percent confidence-level upper limits on the electron-antineutrino flux, obtaining some of the most stringent constraints below 13.3 MeV. Beyond the DSNB search itself, this work demonstrates neural-network-based event classification as a promising approach for suppressing neutron-associated backgrounds in liquid-scintillator neutrino detectors.

astro-ph.HE↗

arXiv2026

The transitional Type Ibn/IIn SN 2022pda, with pre-explosion outbursts and a double-peaked light curve

We report the results of a photometric and spectroscopic follow-up campaign of the unusual interacting supernova (SN) 2022pda. Precursor variability lasting $\sim 100$ days is observed before the explosion. The SN light curve has a double peak shape. It reached a first maximum of $M_{\rm{r}} = -19.6 \pm 0.2$\,mag, followed by an initial two-month decline and a second, broad peak lasting about six months. The early spectra show a blue continuum with dominant H and He emission lines. A high-resolution pre-maximum spectrum shows that the profile of the \Hei~$\lambda$5876 line consists of a moderately narrow ($\sim 1900$ \kms) P~Cygni absorption superposed on a broader ($\sim 3300$ \kms) component. In the blue region, several spectral features are identified, including C {\sc iii}/N {\sc iii}/O {\sc ii} blends. Two broad bumps at 4600--5200 \AA, 6400--6800~\AA\ regions reveal a complex profile, which are likely due to blends of H, He, and other emission lines. Late-time spectra are still dominated by prominent and broad H and He lines in emission. Shock-driven model fits to the bolometric light curve suggest that the SN is powered by interaction with a massive CSM with enhanced mass loss rates $\sim 5$ \msun yr$^{-1}$, expelled during two events occurred $\sim 1$ and $\sim 0.2$ years before the explosion. The overall SN evolution indicates that SN\,2022pda is a transitional event between a H-rich SN IIn (SN\,2009ip-like) and a He-rich SN Ibn. Our findings suggest that the progenitor was likely a Luminous Blue Variable transitioning towards a Wolf--Rayet stage.

astro-ph.HE↗

arXiv2026

A practical Laser-Heated Diamond Anvil Cell synthesis technique and recovery workflow for metastable MnSb2 and YbZn2 phases

The creation and exploration of new materials under extreme pressure-temperature conditions has become increasingly reliant on laser-heated diamond anvil cell (LHDAC) techniques, which provide direct access to previously unexplored regions of multinary phase diagrams. Whereas numerous high-pressure phases have been identified in situ, systematic recovery and post-synthesis physical property characterization of these materials remain significant challenges. In this work, we present the development of an integrated LHDAC synthesis and demonstrate a practical LHDAC-based synthesis workflow that enables stabilization and recovery of metastable intermetallic phases for subsequent structural and transport studies. Using this approach, we successfully achieved LHDAC synthesis of high-pressure MnSb2 and YbZn2 phases under moderate pressures. Synchrotron X-ray diffraction and spatial mapping confirm dominant formation of the targeted phases, whereas laboratory-based refinement quantifies phase fractions despite intrinsic microstrain and minor secondary phases. High-pressure transport measurements on recovered samples reveal tunable by pressure electronic instabilities in both systems. In MnSb2, pressure suppresses two high-temperature magnetic ordering anomalies, observed in transport, by 5 GPa and for higher pressures induces a new low-temperature feature that increases with further pressure increase. In hexagonal high-pressure YbZn2, an electronic reconstruction emerges at ~11 GPa, characterized by semiconducting-like behavior from ~ 30 K to 300 K and a broad low-temperature coherence crossover near 30 K. Our results establish LHDAC synthesis not only as a structural discovery tool, but also as an experimental platform for investigating correlated quantum states stabilized far from equilibrium thermodynamic conditions.

cond-mat.mtrl-sci↗

arXiv2026

Multi-mode Photonic Time Crystals Based on Time-Modulated Metasurface Waveguides

Photonic time crystals are electromagnetic media with periodically time-varying parameters, enabling momentum band gaps, parametric amplification, and frequency conversion beyond what is possible in time-invariant systems. So far, they have been explored mainly in single-mode systems, which limits the range of accessible physical phenomena. Here, we introduce an impenetrable metasurface waveguide as a multimode time-varying platform supporting both guided surface modes and higher-order guided volume modes. We show that temporal modulation in this platform gives rise not only to conventional intramodal band gaps associated with same-branch coupling, but also to tilted intermodal band gaps originating from coupling between different guided-mode branches. Unlike intramodal band gaps, these intermodal band gaps are not restricted to half the modulation frequency and can enable directional wave amplification, where the amplified field carries energy along the waveguide even inside the band gap. We further show that the modulation phase difference provides an effective symmetry-control parameter: by exploiting temporal glide symmetry, one can selectively suppress or enhance gap opening for interactions between modes of the same or different symmetry. These results establish a versatile multimode platform for photonic time crystals, offering one of the simplest and most experimentally accessible routes to tilted band gaps compared with volumetric dispersive PTC implementations and, more broadly, opening new opportunities for time-varying electromagnetic systems.

physics.optics↗

arXiv2026

Multi-wavelength outburst activity from EP J174942.2-384834: a very faint X-ray transient discovered by Einstein Probe

We report the discovery and multi-wavelength characterization of the Galactic transient EP J174942.2$-$384834, first detected by the Einstein Probe during a faint X-ray outburst in March 2025. Coordinated follow-up observations revealed two major outbursts and a rebrightening over a seven-month period. Broadband X-ray spectral modeling shows that the outburst emission was dominated by thermal Comptonization of very soft seed photons. The absence of a detected thermal disk component, together with the low inferred seed-photon temperature, is consistent with a cool and possibly truncated accretion disk. The X-ray spectrum remained consistently hard throughout the outburst activity, with a power-law photon index of $\Gamma \approx 1$-2, gradually softening as the flux declined. The optical/UV counterpart brightened in tandem with the X-ray emission and exhibited a blue continuum with broad Balmer absorption features. Together with the optical/UV - X-ray luminosity correlation, this supports a disk-dominated origin of the optical/UV outburst emission, with viscous heating likely playing a major role and irradiation possibly contributing, especially in the UV. No radio counterpart was detected, implying at most very faint jet activity. Taken together, the observed properties support the classification of EP J174942.2$-$384834 as a very faint X-ray transient black hole candidate. This study demonstrates the ability of Einstein Probe to uncover and characterize the faintest accreting compact objects in the Galaxy.

astro-ph.HE↗

arXiv2026

Ellipsoidal modulation and multi-wavelength activity in the pre-cataclysmic binary RX J1553.0+4457

RX J1553.0+4457 (TMTS J15530469+4457458) is a detached post-common-envelope binary containing a cool white dwarf and an active late-type companion. We present a multi-wavelength study combining BOOTES multi-band photometry, six sectors of public TESS full-frame imaging, Einstein Probe/FXT X-ray observations, CAFOS optical spectroscopy, and archival ultraviolet-to-mid-infrared photometry. The BOOTES data reveal two short optical flares separated by about 3 h, with amplitudes of roughly 1-1.5 mag and faster decay at shorter wavelengths. The combined TESS light curve shows a stable signal at P = 0.083782 d, consistent with the first harmonic of the known spectroscopic orbital period, and its folded morphology indicates ellipsoidal modulation from a tidally distorted late-type companion rather than an irradiation-dominated waveform. TESS flare energetics lie in the active M-dwarf regime. The Einstein Probe/FXT spectra show a factor of about 4 decline in the 0.3-10 keV flux, mainly associated with decreasing emission measures. The broadband SED is reproduced by a cool white dwarf plus a late-type M dwarf, with no clear hot-continuum or mid-infrared excess. RX J1553.0+4457 is therefore best interpreted as a detached pre-cataclysmic binary whose rapid optical variability is dominated by magnetic activity and whose orbital modulation is ellipsoidal, although a weak wind-fed or intermittent accretion contribution remains possible.

astro-ph.SR↗

arXiv2026

The nEXO Radioassay Program

Material radioactivity compilations, such as the one presented here, are important enablers of science. They are useful for the selection of radiopure materials used in the design and construction of low-energy rare-event search experiments. They allow researchers developing such experiments to save time on material studies and avoid costly duplication of effort. The data presented here were generated in support of the planned nEXO double-beta decay search. This work contains among the most restrictive constraints on the natural radioactivity content of materials of general interest to the low-radioactivity community, found in any tabulation of this kind. In this study, various techniques were employed; they are described here.

physics.ins-det↗

arXiv2026

Features of spherical torus p 11B burning plasmas

A spherical torus (ST) p B11 plasma model that satisfies multi-magnetofluid force balance is developed, which includes small fractions of suprathermal ions with temperatures around 0.5 MeV and suprathermal electrons in the MeV range. Alongside the primary thermal plasma with ion temperatures exceeding 100 keV and densities above 10E20 m-3, these components enhance fusion reaction rates by leveraging the p B11 double-peak fusion cross section. Suprathermal ions and strong toroidal rotation driven by neutral beam injection have been observed in devices such as START, MAST, NSTX, Globus-M2, and ST40. Central-solenoid-free plasma initiation, ramp-up, and sustainment were tested on EXL-50 and replicated on EXL-50U with partial central induction, demonstrating efficient current drive and consistent with the multi-magnetofluid equilibrium model. Motivated by ENN's aneutronic commercial fusion roadmap, this paper presents a rotating, thermally un-equilibrated ST p B11 plasma with unique properties: fluid components experience separate balance under centripetal, electrostatic, and Lorentz forces with common electric and magnetic fields, leading to large rotation speed differences between thermal boron ions and suprathermal protons; a large outboard region with magnetic well and omnigeneity is created, affecting neoclassical transport and gradient-driven turbulence; suprathermal charged particles can extend beyond the last closed flux surface and be limited by plasma-facing components, influencing recycling and pedestal conditions; and the superposition of these plasma components modifies sources and sinks of free energy, prompting renewed evaluation of stability, turbulence, transport, heating, current drive, and flux diffusion. Challenges and opportunities for sustained burn are discussed for a compact p B11 ST with 1.4-meter major radius, 13-MA current, and 3-T toroidal field.

physics.plasm-ph↗

arXiv2026

Measurement of coherent elastic neutrino nucleus scattering on germanium by COHERENT

The COHERENT collaboration reports the most precise measurement of the coherent elastic neutrino-nucleus scattering cross section to date. This measurement was performed with COHERENT's germanium detector array, Ge-Mini, at the Spallation Neutron Source at Oak Ridge National Laboratory. A cumulative exposure of $4.68\times10^{22}$ protons on target yielded a total number of observed counts of $124^{+14}_{-12}$ and a flux-averaged cross section of $1.00 \pm 0.10 \mathrm{(statistical)} \pm 0.10 \mathrm{(systematic)}$ relative to the standard-model expectation of $5.9\times10^{-39} \mathrm{cm}^2$. The well-understood energy and timing distributions of the neutrino source allow for independent measurements of muon- and electron-neutrino scattering rates. This information is used to improve constraints on non-standard neutrino interactions mediated by heavy particles.

hep-ex↗

arXiv2026

Design of a high voltage delivery system for noble liquid time projection chambers

Noble liquid time projection chambers (TPCs) are a leading technology in the detection of ionizing radiation, particularly in applications such as accelerator neutrino physics, dark matter detection, and neutrinoless double beta decay. This paper addresses the design considerations for implementing stable high voltage (HV) systems within large noble liquid TPCs, with a focus on the nEXO experiment. Utilizing insights from prior HV research and experimental investigations, we outline factors influencing HV stability and discuss design choices to improve stability and prevent electrical discharges. A novel HV delivery system concept is presented, tailored for the nEXO TPC, which incorporates these design considerations while also meeting the stringent radiopurity requirements of the nEXO neutrinoless double beta decay search. These design considerations and their specific implementation towards a HV delivery system offer guidance to future experiments applying high voltage in noble liquid environments.

physics.ins-det↗