arXiv subjects

Xiaorong Zhou

Publications and source records attributed to Xiaorong Zhou.

At least 19 recordsLinked to original sources

arXiv2026

Feasibility Study of $e^+e^-\to η_cJ/ψ$ Production and Fully-Charmed Tetraquark Searches at STCF

The proposed high-luminosity Super Tau-Charm Facility (STCF) offers a clean experimental environment for threshold studies of exotic hadrons. In this Letter, we evaluate the expected significance for the fully-charmed vector tetraquark candidate $T_{4c}$ in the $e^+e^- \to η_c J/ψ$ channel at the STCF. Using Monte Carlo simulations of an energy scan from $\sqrt{s}=6.71$ to $6.79~\mathrm{GeV}$ with $100~\mathrm{fb}^{-1}$ per point, we adopt a high-efficiency single-tag (ST) reconstruction of $J/ψ$ leptonic decays as the primary strategy, with a double-tag (DT) reconstruction of $η_c \to K^+K^-π^0$ retained as an independent cross-check. Because the signal cross section is governed by the still-uncertain dielectron width $Γ_{ee}$, we consider three benchmark hypotheses, $Γ_{ee}=0.25, 0.5, 1~\mathrm{eV}$. The corresponding expected ST significances are $5.1\,σ$, $10.6\,σ$, and $20.5\,σ$, respectively. These results indicate that the STCF can provide meaningful sensitivity to fully-charmed tetraquark states near threshold.

hep-ex↗

arXiv2026

Spin correlation of hyperon-antihyperon systems in $e^+e^-$ annihilation

Quantum correlations in high-energy collisions provide a novel perspective on both fundamental physics and hadron structure. We calculate the quantum information observable in spin-1/2 particle-antiparticle systems produced in $e^+e^-$ annihilation. Starting from the two-qubit density operator, we calculate the Bell variable, concurrence and negativity as functions of the scattering angle and collision energy for the $Λ\barΛ$, $Σ^+\barΣ^-$, and $Λ^+_c\barΛ^-_c$ systems in the process $e^+e^-\rightarrow B\bar{B}$ at BESIII experiments. Unlike elementary particle-antiparticle systems, the hyperon-antihyperon system exhibits non-vanishing transverse polarization for $B$ and $\bar{B}$ with respect to the production plane, which significantly restrict the kinematic region where the CHSH inequality is violated while leaving the entanglement largely unaffected. We also extend our analysis to the general case of spin-1/2 particle-antiparticle production, and explore the potential of using quantum correlations as probes to hadron structure, particularly to the parton-level entanglement inside heavy-flavored mesons.

hep-ph↗

arXiv2026

Long-lived sterile neutrinos from axionlike particles at the Super Tau-Charm Facility

We study the search prospect of long-lived heavy neutral leptons (HNLs) pair produced in decays of axionlike particles (ALPs) at the proposed Super Tau--Charm Facility (STCF), focusing on the center-of-mass energy of $\sqrt{s}=3.773$ GeV. The ALPs are assumed to originate from $D^\pm$-meson decays in association with a charged pion. We perform both truth-level and detector-level Monte Carlo simulations and obtain the expected sensitivity reach to the mixing parameter between the HNL and the electron neutrino, $|V_{eN}|^2$, with a displaced-vertex search at STCF. We find that STCF can probe values of $|V_{eN}|^2$ about one-to-two orders of magnitude beyond the existing bounds. We also perform an approximate reinterpretation of a search for HNLs at the CHARM experiment, which is subject to model-dependent assumptions on the production and kinematic distributions, and find that beam-dump experiments may provide strong complementary constraints.

hep-ph↗

arXiv2026

Searching for apparent baryon number violation in $Λ_c^+$ decays at the Super Tau-Charm Facility

Observation of baryon number violation (BNV) in laboratory experiments would constitute unambiguous evidence for physics beyond the Standard Model. We propose dedicated searches for \textit{apparent} BNV in charm-baryon decays, $Λ_c^+\to M^+ +$ missing energy ($M=π, K$) where the missing energy stems from a resonance. These channels have not been explored experimentally so far, despite the relatively clean environment potentially provided by near $Λ_c^+\overlineΛ_c^-$ threshold production at $e^+e^-$ colliders. Performing state-of-the-art Monte Carlo simulations for the proposed Super Tau-Charm Facility (STCF), we evaluate the signal efficiencies and derive projected model-independent sensitivities under the assumption of negligible background. We further interpret these sensitivities within two theoretical frameworks: a sterile-neutrino-extended low-energy effective field theory ($ν$LEFT) and R-parity-violating (RPV) supersymmetry. With an integrated luminosity of 1 ab$^{-1}$, STCF can probe new-physics scales of several TeV in the $ν$LEFT description and constrain the RPV model parameter $λ''_{212}/m^2_{\tilde{q}}$ down to about $0.1~\mathrm{TeV}^{-2}$. Our results demonstrate that STCF provides a highly competitive opportunity for probing BNV interactions in rare charm-baryon decays.

hep-ph↗

arXiv2026

Entanglement measures and Bell-type spin-correlation observables in tau-lepton pairs at the Super Tau-Charm Facility

Within the framework of quantum field theory and the Standard Model (SM), we investigate the prospects of studying entanglement measures and Bell-type spin-correlation observables in the electroweak process $e^- e^+\to τ^-τ^+$ at the center-of-mass (COM) energies of $\sqrt{s}=3.670,4.630$, and $7.000$ GeV at the proposed Super Tau-Charm Facility (STCF) in China. Focusing on the hadronic decay channel $τ^\pm\to π^\pm ν$, we determine the spin-correlation coefficients of the $τ^-τ^+$ system within the SM framework using measurable production kinematics, namely the $τ$ velocities and scattering angles in the COM frame. From these correlation coefficients, we construct concurrence and a Bell-type correlation combination as defined in the literature. Assuming an integrated luminosity of 1 ab$^{-1}$ for each considered COM energy, and incorporating realistic detector efficiencies as well as statistical and systematic uncertainties, we estimate the expected sensitivity to these observables at STCF. Our results indicate that, under the SM hypothesis, the corresponding Bell-type correlation combinations could be resolved with high statistical significance at STCF.

hep-ph↗

arXiv2026

Observation of Orbit-Orbit Torques: Highly Efficient Torques on Orbital Moments Induced by Orbital Currents

We study the current-induced torques in bilayers composed of a light 3d metal, chromium, and a rare-earth ferromagnet with finite orbital moments, terbium, utilizing second-harmonic Hall-response measurements. The dampinglike torque efficiency of chromium is found to be positive and reaches ~3.66 in this system, in sharp contrast to the negative and subtle dampinglike torque efficiency in general Cr/ferromagnet heterostructures with quenched orbital moment. We suggest that the orbital currents generated by the orbital Hall effect in Cr can be injected into Tb with negligible loss at the interface and then efficiently interact with the orbital moments. We term such an exotic effect as the orbit-orbit torque (OOT). Our work implies that orbital currents could be harnessed to manipulate the orbital magnetization of materials, which would advance the development of orbitronics.

cond-mat.mes-hall↗

arXiv2025

Prospects of $|V_{us}|$ and axial vector form factors in $Λ\to pe^{-}{\barν}_{e}$ decay at STCF

We report a feasibility study of the semileptonic decay $Λ\to pe^{-} {\barν}_{e}$ by using a fast simulation software package at STCF. With an anticipated integrated luminosity of 3.4 trillion $J/ψ$ per year at a center-of-mass energy at 3.097 GeV, the statistical sensitivity of the branching fraction is determined to be 0.15\%. The statistical sensitivities of form factors $g_{av}$ and $g_w$ are determined to be 0.4\% and 2.15\%, respectively. Combining this result with $g_1(0)$ from Lattice QCD, we can obtain the projected sensitivity of $|V_{us}|$, to be 0.9\%, which is comparable to the precision obtained through meson decay measurements. The precise measurement to be obtained at STCF will provide a rigorous test of Standard Model.

hep-ex↗

arXiv2025

Sensitivity Study of the Tau Lepton Electric Dipole Moment at the Super Tau-Charm Facility

This study investigates the intrinsic electric dipole moment (EDM) of the $τ$ lepton, which is an important quantity in the search for physics beyond the Standard Model (BSM). In preparation for future measurements at the Super Tau-Charm Facility (STCF), we employ Monte Carlo simulations of the $e^+e^- \rightarrow τ^+τ^-$ process and optimize the analysis methodology for EDM extraction. Machine learning techniques are implemented to efficiently identify signal events ($τ^\pm\rightarrowπ^\pmπ^0ν_τ$), which result in a significant improvement in signal-to-noise ratio. Our optimized event selection algorithm achieves $80.0\%$ signal purity with $6.3\%$ efficiency. We develop an analytical approach for $τ$ lepton momentum reconstruction and derive the squared spin density matrix along with optimal observables, which maximize the sensitivity to $d_τ$. The relationship between these observables and the EDM is established with the estimated sensitivity of $|d_τ| < 3.89\times 10^{-18}\,e\cdot\mathrm{cm}$ at a $68\%$ confidence level. These results provide a foundation for future experimental measurements of the $τ$ lepton EDM in STCF experiments.

hep-ex↗

arXiv2025

Spin-Splitting Magnetoresistance in Altermagnetic RuO2 Thin Films

The recently discovered altermagnets, featured by the exotic correlation of magnetic exchange interaction and alternating crystal environments, have offered exciting cutting-edge opportunities for spintronics. Nevertheless, the altermagnetism of RuO2, one of the earliest-discovered altermagnets, is currently under intense debate. Here we try to resolve this controversy by demonstrating an altermagnetic spin-splitting magnetoresistance (SSMR) effect that is driven by a spin current associated with the giant nonrelativistic spin splitting of an altermagnet. Compared to the spin Hall magnetoresistance induced by a conventional relativistic spin current, the SSMR is characterized by unusual angular dependence with a phase-shift feature underpinned by the Neel-vector orientation and pronounced temperature dependence caused by its susceptibility to electron scattering. Through systematical investigations on the magnetoresistance of (101)-RuO2/Co bilayers, we disentangle a sizable SSMR and hence unveil a Neel vector along [001] direction. Our work not only demonstrates a simple electric avenue to probing the Neel vector of altermagnets, but also indicates long-range magnetic order in thin films of RuO2.

cond-mat.mes-hall↗

arXiv2025

Status and prospect of weak radiative hyperon decays

Weak radiative hyperon decays represent a rich interplay between weak interactions and the internal structure of baryons, offering profound insights into Quantum Chromodynamics and weak interactions. Recent experimental observations, particularly from BESIII, have revealed deviations from theoretical predictions. These deviations could signal new physics or the need for refined theoretical models incorporating intermediate resonance effects. This review discusses recent theoretical advancements and key experimental findings, focusing on recent measurements from BESIII and their implications for strong interactions and baryon structure.

hep-ph↗

arXiv2025

CP violation studies at Super Tau-Charm Facility

Charge-parity ($C\!P$) violation in the tau-charm energy region is a promising area for sensitive tests of Standard Model (SM) predictions and searches for new, beyond the SM physics. A future Tau-Charm Facility that operates at center-of-mass energies between 2.0 and 7.0 GeV, with a peak luminosity of $0.5\times10^{35}$~cm$^{-2}$s$^{-1}$, would provide huge numbers of hadrons and tau ($τ$) leptons that are produced in low-background environments and with well understood kinematic properties. In this report, prospects for unique studies of $C\!P$ violation in the decay of charmed hadrons, and in the production and decay of hyperons and $τ$ leptons at a next-generation tau-charm facility are discussed. In addition, opportunities for improved tests of $CPT$ invariance test in $K^{0}-\bar{K}^{0}$ mixing are presented.

hep-ex↗

arXiv2023

Semiconducting transport in Pb$_{10-x}$Cu$_x$(PO$_4$)$_6$O sintered from Pb$_2$SO$_5$ and Cu$_3$P

The very recent claim on the discovery of ambient-pressure room-temperature superconductivity in modified lead-apatite has immediately excited sensational attention in the entire society, which is fabricated by sintering lanarkite (Pb2SO5) and copper(I) phosphide (Cu$_3$P). To verify this exciting claim, we have successfully synthesized Pb$_2$SO$_5$, Cu$_3$P, and finally the modified lead-apatite Pb$_{10-x}$Cu$_x$(PO$_4$)$_6$O. Detailed electrical transport and magnetic properties of these compounds were systematically analyzed. It turns out that Pb$_2$SO$_5$ is a highly insulating diamagnet with a room-temperature resistivity of ~7.18x10$^9$ Ohm.cm and Cu$_3$P is a paramagnetic metal with a room-temperature resistivity of ~5.22x10$^{-4}$ Ohm.cm. In contrast to the claimed superconductivity, the resulting Pb$_{10-x}$Cu$_x$(PO$_4$)$_6$O compound sintered from Pb$_2$SO$_5$ and Cu$_3$P exhibits semiconductor-like transport behavior with a large room-temperature resistivity of ~1.94x10$^4$ Ohm.cm although our compound shows greatly consistent x-ray diffraction spectrum with the previously reported structure data. In addition, when a pressed Pb$_{10-x}$Cu$_x$(PO$_4$)$_6$O pellet is located on top of a commercial Nd$_2$Fe$_{14}$B magnet at room temperature, no repulsion could be felt and no magnetic levitation was observed either. These results imply that the claim of a room-temperature superconductor in modified lead-apatite may need more careful re-examination, especially for the electrical transport properties.

cond-mat.supr-con↗

arXiv2023

Novel approach to investigate $η$ decays via $η'\rightarrowππη$

To avoid the impact from the background events directly from $e^+e^-$ annihilations or $J/ψ$ decays, we propose a novel approach to investigate $η$ decays, in particular for its rare or forbidden decays, by using $η^\prime\rightarrowππη$ produced in $J/ψ$ decays at the $τ-$charm factories. Based on the MC studies of a few typical decays, $η\rightarrow ππ$, $γl^+l^- (l= e, μ)$, $l^+l^-$, as well as $l^+l^-π^0$, the sensitivities could be obviously improved by taking advantage of the extra constraint of $η^\prime$. Using one trillion $J/ψ$ events accumulated at the Super $τ$-Charm facility, the precision on the investigation of $η$ decays could be improved significantly and the observation of the rare decay $η\rightarrow e^+e^-$ is even accessable.

hep-ph↗

arXiv2023

Topotactic Transition: A Promising Opportunity for Creating New Oxides

Topotactic transition is a structural phase change in a matrix crystal lattice mediated by the ordered loss/gain and rearrangement of atoms, leading to unusual coordination environments and metal atoms with rare valent states. As early as in 1990s, low temperature hydride reduction was utilized to realize the topotactic transition. Since then, topological transformations have been developed via multiple approaches. Especially, the recent discovery of the Ni-based superconductivity in infinite-layer nickelates has greatly boosted the topotactic transition mean to synthesizing new oxides for exploring exotic functional properties. In this review, we have provided a detailed and generalized introduction to oxygen-related topotactic transition. The main body of our review include four parts: the structure-facilitated effects, the mechanism of the topotactic transition, some examples of topotactic transition methods adopted in different metal oxides (V, Mn, Fe, Co, Ni) and the related applications. This work is to provide timely and thorough strategies to successfully realize topotactic transitions for researchers who are eager to create new oxide phases or new oxide materials with desired functions.

cond-mat.mtrl-sci↗

arXiv2023

Production and decay of polarized hyperon-antihyperon pairs

Polarized hyperon-antihyperon pairs shed light on various unresolved puzzles in contemporary physics: How the strong interaction confines quarks into hadrons, how accurately the Standard Model describes microcosmos and even why our universe consists of so much more matter than antimatter. Thanks to their weak, parity violating decays, hyperons reveal their spin properties. This can be exploited e.g. the decomposition of the electromagnetic structure of hyperons, precision tests of flavour symmetry and searches for CP violation. At the BESIII experiment at BEPC-II, Beijing, China, hyperon-antihyperon pairs can be produced in abundance. Recently collected large data samples have triggered the development of new methods that provide unprecedented precision and a plethora of new results have emerged. When applied at future high-intensity facilities like PANDA and STCF, precision physics will be taken to a new level which can contribute to the solution to the aforementioned puzzles.

hep-ph↗

arXiv2023

Sensitivity of $CP$ Violation of $Λ$ decay in $J/ψ\to Λ\barΛ$ at STCF

The process of $J/ψ\to Λ\barΛ$ is studied using $1.0\times10^{12}$ $J/ψ$ Monte Carlo (MC) events at $\sqrt{s}$=3.097 GeV with a fast simulation software at future Super Tau Charm Facility (STCF). The statistical sensitivity for $CP$ violation is determined to be the order of $\mathcal{O} (10^{-4})$ by measuring the asymmetric parameters of the $Λ$ decay. Furthermore, the decay of $J/ψ\to Λ\barΛ$ also serves as a benchmark process to optimize the detector responses using the interface provided by the fast simulation software.

hep-ph↗

arXiv2022

50 Years of Quantum Chromodynamics

This paper presents a comprehensive review of both the theory and experimental successes of Quantum Chromodynamics, starting with its emergence as a well defined theory in 1972-73 and following developments and results up to the present day. Topics include a review of the earliest theoretical and experimental foundations; the fundamental constants of QCD; an introductory discussion of lattice QCD, the only known method for obtaining exact predictions from QCD; methods for approximating QCD, with special focus on effective field theories; QCD under extreme conditions; measurements and predictions of meson and baryon states; a special discussion of the structure of the nucleon; techniques for study of QCD at high energy, including treatment of jets and showers; measurements at colliders; weak decays and quark mixing; and a section on the future, which discusses new experimental facilities or upgrades currently funded. The paper is intended to provide a broad background for Ph.D. students and postdocs starting their career. Some contributions include personal accounts of how the ideas or experiments were developed.

hep-ph↗

arXiv2022

New Window on Matter-Antimatter Differences

Recent measurements of $CP$-related comparisons of the weak-interaction parameters that describe the decays of the $Ξ^-$ and the $\barΞ^+$ doubly strange hyperon and antihyperon are reviewed and their significance is discussed.

hep-ex↗