arXiv subjects

J. Zhou

Publications and source records attributed to J. Zhou.

At least 19 recordsLinked to original sources

arXiv2026

Abstract Orlicz-Morrey spaces and applications

This work introduces a class of abstract Orlicz-Morrey spaces endowed with a ball-basis on general measure spaces and defines the associated concept of $\Psi$-bounded oscillation operators. Within this framework, we establish pointwise estimates and norm inequalities for these operators via sparse domination techniques. As applications, we verify that this class of $\Psi$-bounded oscillation operators includes maximal operators and Carleson-type operators on general measure spaces, as well as $\omega$-Calder\'on-Zygmund operators and intrinsic square operators on $\mathbb{R}^n$, thus providing a generalization of certain classical Orlicz-Morrey spaces and their associated operator theory.

math.FA↗

arXiv2026

Magnetic precession induced spin accumulation in collinear antiferromagnets

Generating and characterizing uniform and staggered spin polarization in antiferromagnets is one of the key challenges for antiferromagnetic spintronic technology. Here, we perform perturbative theory, group-theoretical symmetry analysis, low energy and ab initio simulations to propose that the magnetic precession near the equilibrium magnetic axis could generate finite uniform and staggered spin polarization at the opposite magnetic sublattices (referring to total magnetic and N\'eel vector generation) in a single AFM semiconductors. This response does not require the heterojunction setup and could eliminate the lattice mismatch issues at the junction. Through scrutinizing all symmetrically-protected vanishing magnetic moment groups and especially focusing on parity-time (PT ) invariant groups, we identify the symmetry constraints that describe the staggered spin accumulation responses, and disclose their fieldlike and dampinglike characters. This unravels a hidden spin accumulation mode in AFM semiconductors. Furthermore, we simulate such an effect using a perturbative approach and suggest that electric gate field and Floquet light-dressing can effectively manipulate these responses.

cond-mat.mtrl-sci↗

arXiv2026

Second-order optimality conditions for optimization problems with generalized equation constraints

This paper provides second-order optimality conditions for optimization problems with generalized equation constraints (GEPs), a framework that encompasses several important and challenging models in mathematical programming, including mathematical programs with variational inequality constraints (MPVIs) and bilevel programs. The obtained optimality conditions are novel even for these particular problem classes. As an application, second-order optimality conditions for MPVIs are detailed. The technical key lies in developing first- and second-order variational analysis of the highly intricate constraint system, which is needed to capture the local curvature of the feasible set entering these optimality conditions. Part of this task was already carried out in our companion paper \cite{BeGfrYeZhangZhou}, and here we complete the study. Comprehensive variational analysis results are derived, which are of independent interest.

math.OC↗

arXiv2025

Threshold $J/\psi$ Photoproduction as a Probe of Nuclear Gluon Structure

The nuclear EMC effect is the observation that quark distributions in bound nucleons experience significant modification at large $x$ relative to free nucleons. Despite decades of measurements verifying the presence of this effect in quarks across a wide range of nuclei, behavior of large-$x$ gluons in nuclei remains almost completely unknown. As the nuclear physics community seeks out new observables to try to elucidate the mechanisms behind the EMC effect, it becomes striking that we remain ignorant regarding the impact of nuclear effects on gluonic behavior. Recent photonuclear data using the Hall D photon beam have enabled the first measurement of $J/\psi$ photoproduction from nuclei near and below the energy threshold, with the results highlighted in Physical Review Letters as an Editors' Suggestion. These data have placed the first, and currently only, constraints on the behavior of large-$x$ gluons within bound nucleons. However, compared to the quantity of data which currently informs our knowledge of the quark-sector EMC effect, these data are extremely limited, and remain unable to conclusively observe or exclude large modification of gluon distributions. A high-luminosity photonuclear experiment will enable a precision measurement of incoherent $J/\psi$ photoproduction at and below the threshold region. This data will provide the first stringent constraints on nuclear modification of gluon structure or other exotic effects which could impact the production of $J/\psi$ from nuclei. We request 85 PAC days at Hall D using the GlueX detector with a 12 GeV electron beam energy and a coherent photon peak energy of $8$ GeV, split into 80 days using a $^4$He target and 5 calibration days using a $^2$H target.

nucl-ex↗

arXiv2025

Contrasting Light-Induced Spin Torque in Antiferromagnetic and Altermagnetic Systems

Light-matter interaction has become one of the promising routes to manipulating various physical feature of quantum materials in an ultrafast kinetics. In this work, we focus on the nonlinear optical effects of the spintronic behavior in antiferromagnetic (AFM) and altermagnetic (AM) systems with compensated magnetic moments, which has been extensively attractive for their potential applications. With vanishing net magnetic moments, one of the main concerns is how to distinguish and disentangle AFMs and AMs in experiments, as they usually behave similarly in many susceptibility measurements. To address this challenge, we propose that linearly polarized light could trigger contrasting nonequilibrium local spin torques in these systems, unravelling hidden light-induced spintronic behaviors. In general, one could achieve light-induced spin canting in AMs, while only Neel vector torques in AFMs. We scrutinize and enumerate their symmetry constraints of all 122 magnetic point groups. We also adopt low energy Hamiltonian models and first-principles calculations on two representative materials to illustrate our theory. Our work provides a new perspective for the design and optimization of spintronic devices.

cond-mat.mtrl-sci↗

arXiv2025

Valley-dependent giant orbital moments and transport feature in rhombohedral graphene multilayers

Recent years have witnessed a great interest in orbital related electronics (also termed as orbitronics). In the current work, we present a first-principles density functional theory calculation on the orbital magnetic moments, intrinsic orbital Hall effect, and ordinary magnetoconductivity effects in rhombohedral graphene multilayers. Our calculations suggest a giant orbital moment that arises from inter-atomic cycloid motion, reaching over 30 muB under an intermediate gate voltage. This leads to a valley polarization under an external magnetic field, as observed in recent experiments [Nature 623, 41-47 (2023)]. In addition, the orbital-related transport feature exhibit significant responses that are potentially observed in experiments. We also suggest that under a periodic field driven (such as high frequency light field), the ungated graphene multilayers could host strong quantum anomalous and orbital Hall effects, engineered by the layer number. As the graphene multilayers are intrinsically nonmagnetic with negligible spin-orbit coupling, the orbital moments would not be entangled by spin-related signals. Thus, they serve as an ideal platform to conduct orbitronic measurements and utilization for next generation information read/write nanodevices.

cond-mat.mtrl-sci↗

arXiv2025

Unraveling phase transformation with phononic hyperbolicity using off-resonant terahertz light

Noncontacting and nondestructive control of geometric phase in conventional semiconductors plays a pivotal role in various applications. In the current work, we present a theoretical and computational investigation on terahertz (THz) light-induced phase transformation of conventional binary semiconducting compounds among different structures including rock-salt, zinc-blende, wurtzite, and hexagonal phases. Using MgS and MgSe as prototypical examples, we perform anharmonic phonon mediated calculations and reveal large contrasting lattice contributed dielectric susceptibility in the THz regime. We then construct a THz-induced phase diagram under intermediate temperature and reveal rock-salt to hexagonal and then wurtzite structure transformations with increasing light intensity. This does not require a high temperature environment as observed in traditional experiments. The low energy barrier suggests that the phase transition kinetics can be fast, and the stable room temperature phonon dispersions guarantee their non-volatile nature. Furthermore, we disclose the phononic hyperbolicity with strong anisotropic THz susceptibility components, which serves as a natural hyperbolic material with negative refractive index. Our work suggests the potential to realize metastable hidden phases using noninvasive THz irradiation, which expands the conventional pressure-temperature ($P-T$) phase diagram by adding light as an additional control factor.

cond-mat.mtrl-sci↗

arXiv2025

Reversing Neel Vector in PT-Antiferromagnets by Nonreciprocal Light Scattering

Antiferromagnetic (AFM) spintronics has been receiving tremendous attention due to their ultrafast kinetics, zero stray field, immune to external magnetic field, and potential to minimizing magnetic storage devices. The optical control of AFM Neel vector has become a hectic topic during recent years, which could facilitate the AFM utilization in practical systems. In this work, we propose a nonreciprocal light scattering mechanism to flip the Neel vector in parity-time (PT) combined AFM multilayers, by estimating the energy contrast between the bistable Neel polarization configurations. We illustrate our theory using a low energy kp model, and perform ab initio calculations on two typical A-type AFM materials, MnBi2Te4 and CrI3 thin films. We show that varying incident photon frequency could modulate the relative stability between the bistable Neel vector state, which also depends on the light handedness. According to this theory, our parameter-independent calculations on the Neel vector diagram shows consistent predictive results with recent experimental observations. This mechanism provides an effective route to controlling the AFM order parameter through photo-magnetic interaction.

cond-mat.mtrl-sci↗

arXiv2024

Quasielastic $\overrightarrow{^{3}\mathrm{He}}(\overrightarrow{e},{e'})$ Asymmetry in the Threshold Region

A measurement of the double-spin asymmetry from electron-$^{3}$He scattering in the threshold region of two- and three-body breakup of $^{3}$He was performed at Jefferson Lab, for Q$^{2}$ values of 0.1 and 0.2 (GeV/$c$)$^{2}$. The results of this measurement serve as a stringent test of our understanding of few-body systems. When compared with calculations from plane wave impulse approximation and Faddeev theory, we found that the Faddeev calculations, which use modern nuclear potentials and prescriptions for meson-exchange currents, demonstrate an overall good agreement with data.

nucl-ex↗

arXiv2024

Pion electroproduction measurements in the nucleon resonance region

We report new pion electroproduction measurements in the $\Delta(1232)$ resonance, utilizing the SHMS - HMS magnetic spectrometers of Hall C at Jefferson Lab. The data focus on a region that exhibits a strong and rapidly changing interplay of the mesonic cloud and quark-gluon dynamics in the nucleon. The results are in reasonable agreement with models that employ pion cloud effects and chiral effective field theory calculations, but at the same time they suggest that an improvement is required to the theoretical calculations and provide valuable input that will allow their refinements. The data illustrate the potential of the magnetic spectrometers setup in Hall C towards the study the $\Delta(1232)$ resonance. These first reported results will be followed by a series of measurements in Hall C, that will expand the studies of the $\Delta(1232)$ resonance offering a high precision insight within a wide kinematic range from low to high momentum transfers.

nucl-ex↗

arXiv2024

Molecular gas excitation in the circumgalactic medium of MACS1931-26

The evolution of galaxies is largely affected by exchanging material with their close environment, the circumgalactic medium (CGM). In this work, we investigate the CGM and the interstellar medium (ISM) of the bright central galaxy (BCG) of the galaxy cluster, MACS1931-26 at z~0.35. We detected [CI](2-1), CO(1-0), and CO(7-6) emission lines with the APEX 12-m and NRO 45-m telescopes. We complemented these single-dish observations with CO(1-0), CO(3-2), and CO(4-3) ALMA interferometric data and inferred the cold molecular hydrogen physical properties. Using a modified large velocity gradient (LVG) model, we modelled the CO and CI emission of the CGM and BCG to extract the gas thermodynamical properties, including the kinetic temperature, the density, and the virialisation factor. Our study shows that the gas in the BCG is highly excited, comparable to the gas in local ultra luminous infrared galaxies (ULIRGs), while the CGM is likely less excited, colder, less dense, and less bound compared to the ISM of the BCG. The molecular hydrogen mass of the whole system derived using [CI](2-1) is larger than the mass derived from CO(1-0) in literature, showing that part of the gas in this system is CO-poor. Additional spatially resolved CI observations in both transitions, CO(1-0) and [CI](2-1), and the completion of the CO SLED with higher CO transitions are crucial to trace the different phases of the gas in such systems and constrain their properties.

astro-ph.GA↗

arXiv2024

Flattening-off of droplet bouncing trend under high ambient gas pressures

It was previously observed that colliding liquid droplets in a gaseous medium tend to bounce off at elevated gas pressure up to about 12 atm. In this letter, we extended the droplet collision experiment to up to 41 atm for the first time and reported a noticeable discovery that the tendency is flattened off at higher pressures. The colliding droplets stop bouncing but start to coalesce beyond a critical Weber number, which increases with pressure but tends to a limit value at 21 atm and above. A scaling analysis taking into account the gas-film dynamics, the rarefied gas effects, and van der Waals force well correlates with the experimental discovery.

physics.flu-dyn↗

arXiv2024

Optomechanical cooling with simultaneous intracavity and extracavity squeezed light

We propose a novel and experimentally feasible approach to achieve high-efficiency ground-state cooling of a mechanical oscillator in an optomechanical system under the deeply unresolved sideband condition with the assistance of both intracavity and extracavity squeezing. In the scheme, a degenerate optical parametric amplifier is placed inside the optical cavity, generating the intracavity squeezing; besides, the optical cavity is driven by externally generated squeezing light, namely the extracavity squeezing. The quantum interference effect generated by intracavity squeezing and extracavity squeezing can completely suppress the non-resonant Stokes heating process while greatly enhancing the anti-Stokes cooling process. Therefore, the joint-squeezing scheme is capable of cooling the mechanical oscillators to their quantum ground state in a regime far away from the resolved sideband condition. Compared with other traditional optomechanical cooling schemes, the single-photon cooling rate in this joint-squeezing scheme can be tremendously enlarged by nearly three orders of magnitude. At the same time, the coupling strength required to achieve ground-state cooling can be significantly reduced. This scheme is promising for cooling large-mass and low-frequency mechanical oscillators, which provides a prerequisite for preparing and manipulating non-classical states in macroscopic quantum systems and lays a significant foundation for quantum manipulation.

quant-ph↗

arXiv2023

Batch test of MRPC3b for CBM-TOF/STAR-eTOF

The Compressed Baryonic Matter (CBM) experiment is one of the major scientific spectrometers of the future Facility for Antiproton and Ion Research (FAIR) in Darmstadt. As one of the core sub-systems in CBM experiment for charged hadron identification, the Time-of-Flight (TOF) system is required to have a time resolution better than 80 ps. According to the final state particle flux distribution, the CBM-TOF will be constructed with several types of Multigap Resistive Plate Chambers (MRPC). In the outer region of the TOF wall where the particle fluxes are around 1 kHz/cm2, MRPCs with ultra-thin float glass electrodes are considered as a cost effective solution. MRPC3b prototypes have been developed and tested with excellent performance which could meet all the requirements. Before the construction of CBM-TOF, approximately 80 MRPC3bs are assembled for the STAR endcap TOF (STAR-eTOF) upgrade at RHIC as part of the FAIR Phase-0 programs for CBM-TOF which provides a valuable opportunity for detector stability test under high flux environments. This paper will introduce the batch test of the MRPC3bs for STAR-eTOF upgrade. Time resolution of better than 70 ps and efficiency of around 95% are achieved. Notably, during the batch test, it has been observed that the noise rates of the two edge strips in each counter are significantly higher than those of the middle strips. Simulations with Computer Simulation Technology (CST)Studio Suite are carried out and several kinds of MRPC prototypes are designed and tested accordingly. Based on the simulation and test results, the design of the MRPC3b has been further optimized, resulting in a significant suppression of noise rates in the edge strips.

physics.ins-det↗

arXiv2023

A new direct detection electron scattering experiment to search for the X17 particle

A new electron scattering experiment (E12-21-003) to verify and understand the nature of hidden sector particles, with particular emphasis on the so-called X17 particle, has been approved at Jefferson Lab. The search for these particles is motivated by new hidden sector models introduced to account for a variety of experimental and observational puzzles: excess in $e^+e^-$ pairs observed in multiple nuclear transitions, the 4.2$\sigma$ disagreement between experiments and the standard model prediction for the muon anomalous magnetic moment, and the small-scale structure puzzle in cosmological simulations. The aforementioned X17 particle has been hypothesized to account for the excess in $e^+e^-$ pairs observed from the $^8$Be M1, $^4$He M0, and, most recently, $^{12}$C E1 nuclear transitions to their ground states observed by the ATOMKI group. This experiment will use a high resolution electromagnetic calorimeter to search for or set new limits on the production rate of the X17 and other hidden sector particles in the $3 - 60$ MeV mass range via their $e^+e^-$ decay (or $\gamma\gamma$ decay with limited tracking). In these models, the $1 - 100$ MeV mass range is particularly well-motivated and the lower part of this range still remains unexplored. Our proposed direct detection experiment will use a magnetic-spectrometer-free setup (the PRad apparatus) to detect all three final state particles in the visible decay of a hidden sector particle for an effective control of the background and will cover the proposed mass range in a single setting. The use of the well-demonstrated PRad setup allows for an essentially ready-to-run and uniquely cost-effective search for hidden sector particles in the $3 - 60$ MeV mass range with a sensitivity of 8.9$\times$10$^{-8}$ - 5.8$\times$10$^{-9}$ to $\epsilon^2$, the square of the kinetic mixing interaction constant between hidden and visible sectors.

nucl-ex↗

arXiv2022

Measured proton electromagnetic structure deviates from theoretical predictions

The visible world is founded on the proton, the only composite building block of matter that is stable in nature. Consequently, understanding the formation of matter relies on explaining the dynamics and the properties of the proton's bound state.A fundamental property of the proton involves the response of the system to an external electromagnetic field. It is characterized by the electromagnetic polarizabilities that describe how easily the charge and magnetization distributions inside the system are distorted by the electromagnetic field. Moreover, the generalized polarizabilities map out the resulting deformation of the densities in a proton subject to an electromagnetic field. They disclose essential information about the underlying system dynamics and provide a key for decoding the proton structure in terms of the theory of the strong interaction that binds its elementary quark and gluon constituents. Of particular interest is a puzzle in the electric generalized polarizability of the proton that remains unresolved for two decades. Here we report measurements of the proton's electromagnetic generalized polarizabilities at low four-momentum transfer squared. We show evidence of an anomaly to the behaviour of the proton's electric generalized polarizability that contradicts the predictions of nuclear theory and derive its signature in the spatial distribution of the induced polarization in the proton. The reported measurements suggest the presence of a new, not-yet-understood dynamical mechanism in the proton and present notable challenges to the nuclear theory.

nucl-ex↗

arXiv2022

Deep learning for the rare-event rational design of 3D printed multi-material mechanical metamaterials

Emerging multi-material 3D printing techniques have paved the way for the rational design of metamaterials with not only complex geometries but also arbitrary distributions of multiple materials within those geometries. Varying the spatial distribution of multiple materials gives rise to many interesting and potentially unique combinations of anisotropic elastic properties. While the availability of a design approach to cover a large portion of all possible combinations of elastic properties is interesting in itself, it is even more important to find the extremely rare designs that lead to highly unusual combinations of material properties (e.g., double-auxeticity and high elastic moduli). Here, we used a random distribution of a hard phase and a soft phase within a regular lattice to study the resulting anisotropic mechanical properties of the network in general and the abovementioned rare designs in particular. The primary challenge to take up concerns the huge number of design parameters and the extreme rarity of such designs. We, therefore, used computational models and deep learning algorithms to create a mapping from the space of design parameters to the space of mechanical properties, thereby (i) reducing the computational time required for evaluating each designand (ii) making the process of evaluating the different designs highly parallelizable. Furthermore, we selected ten designs to be fabricated using polyjet multi-material 3D printing techniques, mechanically tested them, and characterized their behavior using digital image correlation (DIC, 3 designs) to validate the accuracy of our computational models. The results of our simulations show that deep learning-based algorithms can accurately predict the mechanical properties of the different designs, which match the various deformation mechanisms observed in the experiments.

cond-mat.mtrl-sci↗

arXiv2021

Light Output Quenching in Response to Deuterium-ions and Alpha Particles and Pulse Shape Discrimination in Deuterated Trans-stilbene

We characterized the light output response of a new 140 cm3 stilbene-d12 crystal up to 14.1 MeV neutron energies using a coincidence neutron scattering system. We also characterized its light output response to alpha particles in the 5 to 6~MeV energy range. The excellent PSD capability of the stilbene-d$_{12}$ detector allowed us to select light pulses produced by particles of increasing ionization density, namely electrons, protons, deuterium-ions, and alpha particles. The measured fast decay component of the light pulses is increasingly quenched as the ionization density of the particle in the crystal increases. Consistently with this finding, the Birks' quenching parameter of alpha particles is approximately 8.5 times larger compared to the quenching of deuterium ions, produced by neutron scattering interactions. The reported experimental characterization will allow high-fidelity modeling of the detector enabling its application for fast-neutron detection and spectroscopy in nuclear physics, radiation protection, nuclear security, and non-proliferation.

physics.ins-det↗