Materials Science
Double-pulse control of all optical magnetization reversal in Tb/Co multilayers
Sheng Li, Dinar Khusyainov, Rein Liefferink et al. (+7 more)
Recent experiments have shown that femtosecond
laser pulse with a Gaussian intensity profile can induce magnetization reversal in Tb/Co multilayers with a ring-shaped switching pattern within the
laser-irradiated area. Here, we investigate the ultrafast magnetization dynamics leading to such a ring-shaped switching by using double-pulse
laser excitation. The
laser pulses cause heat-induced quenching and subsequent recovery of the
magnetic anisotropy in the multilayers and drive the precessional magnetization switching in the
magnetic multilayers. By adjusting the delay between the two pump pulses, we demonstrate that the recovery process can be manipulated and show, experimentally and numerically, that this allows control over the final
magnetic domain pattern.
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All authors Sheng Li, Dinar Khusyainov, Rein Liefferink, Lukas Körber, Quoc-Trung Trinh, Ricardo C. Sousa, Liliana D. Buda-Prejbeanu, Johan H. Mentink, Theo Rasing, Alexey V. Kimel
High Energy Physics (Theory) · Cross-listed from math.NT
Depth Two Mock Modularity by Eisenstein Series Coupling
Kathrin Bringmann and Caner Nazaroglu
The notion of depth two and higher mock modular forms have found important applications in mathematical physics and enumerative geometry since their inception through indefinite theta functions with general signature. These theta functions generalize Zwegers' work on Lorentzian signature
lattices and the framework of mock modular forms that emanated from it. Mock modular forms can also be studied through Eisenstein and Poincaré series. The interaction of this second point of view with the indefinite theta function approach yields a wealth of tools to unearth the rich structure behind mock modular forms. For mock modular forms of higher depth, on the other hand, indefinite theta functions and their variants largely remained the only available approach. In this paper, we show that one can indeed get mock modular forms of depth two by "coupling" a pair of Eisenstein series that yield depth one mock modular forms, thereby providing a new and independent approach to higher depth mock modular forms. We exemplify this new perspective on a depth two object that appeared in the context of Vafa-Witten invariants.
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High Energy Physics (Theory)
Hidden quantum-informatic symmetries of quasi-de Sitter backgrounds
Suddhasattwa Brahma, Jaime Calderon-Figueroa, Xiancong Luo et al. (+1 more)
We investigate how degeneracies in quasi-de Sitter backgrounds, in the sense of Wands' duality, are reflected in real-space
quantum correlations of
primordial perturbations. Using the continuous-variable Gaussian formalism for coarse-grained scalar fluctuations, we construct the covariance
matrix of a pair of spatially localized modes in inflationary spacetime, and extract the
symplectic invariants of the system. For a generic Wands-dual pair of backgrounds, we find that while the individual entries of the covariance
matrix are highly background-dependent, the
symplectic eigenvalues – and hence the
entanglement entropy, mutual information,
quantum discord and log-negativity – all coincide for the two dual realizations. Our results unveil a new ”
quantum-informatic
symmetry” of the de Sitter
vacuum, according to which local linear
entanglement witnesses constructed from coarse-grained fields cannot distinguish between Wands-dual inflationary histories, even though their background trajectories differ. We show that the special nature of the Wands-duality
symmetry (of being local, scale-independent canonical transformations) is at the heart of this duality.
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All authors Suddhasattwa Brahma, Jaime Calderon-Figueroa, Xiancong Luo, Vincent Vennin
Superconductivity
Quantum phase fluctuations quench chiral superconductivity in twisted overdoped cuprate bilayers
Yin Shi, Mengxian Zhao, Fei Yang et al. (+2 more)
Twisted cuprate
bilayers have been proposed to host
chiral superconductivity at temperatures comparable to their large pairing scale, yet experimental signatures of broken time-reversal
symmetry remain unclear. We show that
quantum phase fluctuations strongly suppress
chiral order in twisted overdoped cuprate
bilayers despite robust intralayer pairing. At a $45^\circ$ twist, we analytically demonstrate that the
chiral transition temperature obeys $T_\chi\propto t^4$ when the single-electron interlayer tunneling amplitude $t$ is weak. This collapse originates from competition between the small Josephson energy scale supporting chirality and the temperature-dependent collective zero-point energy. Chirality consequently survives only in a narrow angular window at ultralow temperatures, with relative-phase
plasma softening above the
chiral transition. A distinct transport signature arising from the
quantum phase fluctuations is a pronounced low-temperature enhancement of the critical current near a magic angle. These findings separate pairing and
chiral ordering scales and offer a possible explanation for the difficulty of observing robust
chiral superconductivity in twisted cuprates.
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All authors Yin Shi, Mengxian Zhao, Fei Yang, Miao Liu, Sheng Meng
High Energy Physics (Phenomenology)
Gluon radiation from a QCD antenna with realistic parton-medium interactions
Carlota Andrés, Liliana Apolinário, Néstor Armesto et al. (+4 more)
The spectrum of coherent
gluon radiation from a
quark-antiquark pair undergoing multiple scatterings within a colored medium is central for understanding in-medium parton cascades. However, current efforts are constrained by reliance on a number of approximations, such as the harmonic oscillator approximation, that are only valid within limited regions of phase space. In this paper, we circumvent this problem by expressing the full in-medium
gluon emission spectrum as a set of differential equations that can be solved numerically. This formalism, previously applied to the case of medium-induced radiation off a single color charge, allows to resum medium interactions to all orders while employing realistic scattering models. The resulting angle and energy distributions of emitted
gluons serve to illustrate the breakdown of color coherence across the entire accessible phase-space, and constitute a definite step towards a higher-precision description of jet observables.
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All authors Carlota Andrés, Liliana Apolinário, Néstor Armesto, André Cordeiro, Fabio Domínguez, Pablo Guerrero-Rodríguez, José Guilherme Milhano
Quantum Physics
Heliciton-Assisted Chirality-Induced Spin Selectivity from Helical Dirac Current
Ju Gao and Fang Shen
We develop a quantized screw-mode mechanism for chirality-induced
spin selectivity (CISS). The corresponding
quantum, termed a heliciton, is a screw-symmetric environmental excitation with phase $\phi-qz$, longitudinal momentum $\hbar q$, and energy $\hbar\Omega_q$. Its absorption and emission convert the static local
chiral vertex developed in our preceding work into an inelastic resonant scattering process. In first Born approximation, absorption maps $\uparrow,k$ to the $\downarrow,k+q$ sideband, whereas emission maps $\downarrow,k$ to the $\uparrow,k-q$ sideband. The two outputs share the sampled-current overlap $\mathcal J_\chi(k)$ but differ in ladder factors, final momenta, and detunings. With spectral factors $\mathcal S_+$ and $\mathcal S_-$, $P_{\rm sb}=[\mathcal S_--\mathcal O(T)\mathcal S_+]/ [\mathcal S_-+\mathcal O(T)\mathcal S_+]$, where $\mathcal O(T)=\exp[-\hbar\Omega_q/(k_BT)]$. An isolated emission or absorption resonance yields $P_{\rm sb}\simeq+1$ or $-1$, respectively, in the resolved sideband sector. Reversing the screw handedness interchanges the
spin identities of the two sidebands while leaving their spectral and occupation weights unchanged, and therefore reverses $P_{\rm sb}$ at every temperature. At high temperature, absorption and emission have nearly equal occupation weights; at low temperature, absorption is exponentially suppressed while spontaneous emission remains.
Liquid-nitrogen temperature can already produce a pronounced asymmetry for higher-$\Omega_q$ modes. Thus a spatially resolved Dirac wave with
spin-dependent helical conserved current couples locally to a heliciton and produces thermally weighted
spin- and momentum-resolved sidebands without an ad hoc
spin-dependent potential.
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Optics
Generation of strongly localized skin solitons in non-Hermitian waveguide arrays with the Kerr effect
Chong Hou, Boris A. Malomed and Qin Zhou
We address two distinct nonlinear propagation problems in nonlinear optical waveguide arrays (WGAs) with non-reciprocal (non-Hermitian) couplings. First, we investigate the light propagation launched by initial excitations of two different types. The single-channel excitation creates stable
solitons supported by the interplay of the Kerr nonlinearity and non-Hermitian skin effect (NHSE). In this case, we derive, by means of the symbolic-regression method, an analytical formula defining the
soliton existence boundary. For the broad-pulse excitation, we produce perturbed
soliton solutions analytically in the continuum approximation, which is accurately corroborated by numerical results. We thus conclude that NHSE accelerates the propagation of the broad
soliton towards the boundary, ultimately causing tight localization at the edge, which is a hallmark of the NHSE in the continuum limit. Second, we identify stationary
solitons in the system – specifically, nonlinear bulk modes in the Hermitian regime and near-edge skin
solitons in the non-Hermitian one. The nonlinear bulk modes are compressed toward the edge of the WGA under the action of the non-reciprocality, which is the nonlinear extension of NHSE.
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Optics
Evanescent absorption spectroscopy of transition metal dichalcogenide materials using guided photoluminescence in Si$_3$N$_4$ photonic waveguides
Victor Gonzalez-Morote, Marianna Sledzinska, Arkadiusz P. Gertych et al. (+3 more)
On-chip integration of two-dimensional transition metal dichalcogenides (TMDs) with photonic waveguides underpins a growing class of compact optoelectronic and sensing devices, whose performance depends on the optical absorption of the 2D material in this integrated environment. We demonstrate source-free, on-chip evanescent absorption spectroscopy of MoS$_2$ and WS$_2$ flakes integrated on Si$_3$N$_4$ waveguides, in which the broadband defect-related photoluminescence of the Si$_3$N$_4$ core itself acts as the internal probe. Light generated inside the core propagates under the TMD flake and is spectrally attenuated by evanescent interaction with the 2D material, and normalizing the transmitted spectrum to a reference waveguide without TMD yields the energy-dependent absorption response without any external illumination. The extracted guided absorption agrees with Raman and local micro-photoluminescence characterization and resolves differences between spatially uniform and non-uniform flakes. A complementary top-pumping scheme recovers guided WS$_2$ photoluminescence, whose spectral reshaping during propagation is quantitatively reproduced by the measured absorption. This source-free platform qualifies 2D materials in their integrated photonic environment and provides a direct route toward waveguide-integrated TMD photodetectors and sensors.
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All authors Victor Gonzalez-Morote, Marianna Sledzinska, Arkadiusz P. Gertych, Syed Hassan Abbas Jaffery, Mariusz Zdrojek, Daniel Navarro-Urrios
Materials Science
In vacuo synthesis of single-layer Ni3(HITP)2 on HOPG surface using metallo-organic precursor
Chuyu Song, Yifei Feng, Henan Chen et al. (+1 more)
Single-layer conjugated metal-organic frameworks (SL c-MOFs) are predicated theoretically to host rich
quantum phases. To date, however, the experimental synthesis has largely resulted in SL c-MOFs on metal substrates, whose intrinsic properties are strongly screened due to substrate hybridization. To overcome this obstacle, here we develop a method to grow clean SL c-MOF Ni3(HITP)2 on a chemically inert substrate of highly oriented pyrolytic graphite (HOPG). By means of an ultra-high
vacuum based multi-step protocol using nickel acetylacetonate [Ni(acac)2] precursor, we obtain continuous single-layer Ni3(HITP)2. Scanning tunneling microscopy reveals a well-defined hexagonal framework with a uniform azimuthal orientation rotated by approximately 30 degrees with respect to the underlying graphite
lattice. Furthermore, we control the growth of
bilayer Ni3(HITP)2 which features an unusual AA stacking configuration. This work establishes metallo-organic chemistry as an efficient route for integrating 2D c-MOFs onto inert substrates, which opens a new avenue for exploring the exotic
quantum properties of SL c-MOFs.
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All authors Chuyu Song, Yifei Feng, Henan Chen, Nian Lin
Chemical Physics
Ai2-Kit: Streamlining AI-Accelerated Ab Initio Workflows for Complex Chemical Systems
Sheng Bi, Wei-Hong Xu, Yong-Bin Zhuang et al. (+47 more)
Molecular simulations of complex chemical systems, such as catalysis, electrochemistry, and energy storage, often need to capture the interplay of effects such as electronic structure, finite-temperature fluctuations, and electric-field response. Such complexity is difficult to address with traditional ab initio calculations, which are limited by the time and length scales they can reach. AI-accelerated ab initio (AI2) methods use machine learning potentials trained on first-principles data to replace expensive electronic-structure calculations, extending ab initio accuracy to these regimes, but their routine application requires reliable workflows that connect first-principles calculations, model training, molecular dynamics, enhanced sampling, trajectory analysis, and HPC orchestration. Here we present ai2-kit, a software toolkit for developing accessible, reproducible, and extensible AI2 workflows. ai2-kit provides high-semantic-density command-line interfaces and Python APIs for structure and
dataset conversion, batch task generation, active-learning screening, job orchestration, and workflow recovery. We demonstrate ai2-kit in four representative applications: active-learning-based machine learning potential construction, free-energy perturbation for redox and acid-base processes, electrochemical machine learning potentials for electrified interfaces, and spectroscopies from machine learning molecular dynamics. ai2-kit also provides AI-
agent skills that help users adapt these use cases into customized workflows for their own chemical systems and computational software stacks. Together, ai2-kit helps turn AI2 methods from bespoke computational protocols into reusable and extensible workflows for complex chemical systems, from model construction to property prediction.
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All authors Sheng Bi, Wei-Hong Xu, Yong-Bin Zhuang, Jia-Xin Zhu, Jiang-Peng Qiu, Yu-Hang Tang, Xiang-Long Du, Qi You, Yun-Pei Liu, Fu-Qiang Gong, Yu-Xin Guo, Yi-Ze Wang, Cheng-Xuan Wang, Zi-Heng Gong, Zi-Qiang Chen, Chang Liu, Siyuan Han, Jian Gu, Jia-Xin Li, Yi-Ming Chen, Lin Huang, Si-Jie Chen, Bo-Ying Huang, Jie-Zhen Xia, Fan-Jie Xu, Su-Yang Zhong, Peng-Wei Xu, Jun-Yi Wang, Xing-Yun Xie, Yu-Lei Gong, Yan-Yi Su, Yue Liu, Rui-Hao Bi, Lang Li, Fei-Teng Wang, Jing-Xiang Zou, Mei Jia, Jie-Qiong Li, Min Lin, Qi-Yuan Fan, Juan-Juan Sun, Jia-Bo Le, Zixuan Wei, Jin-Yuan Hu, Meng-Lei Jia, Yan Sun, Xiao-Hui Yang, Fujie Tang, Feng Wang, Jun Cheng
Cosmology and Nongalactic Astrophysics
Correcting the hydrostatic mass for non-thermal gas motions: a comparison of two approaches
Théo Lebeau, Nabila Aghanim, Jenny Sorce et al. (+1 more)
An accurate estimation of the mass of
galaxy clusters is key to precisely and unbiasedly constraining cosmological parameters through their number count. The hydrostatic mass, estimated from the properties of the intracluster medium (ICM) assuming hydrostatic
equilibrium, sphericity, and thermal-only pressure, is known to be biased by 10 to 20%, most likely due to non-thermal pressure support from gas motions. Two corrections have been proposed: i) replacing the thermal pressure by the total pressure $P_\mathrm{tot}=P_\mathrm{th}+P_\mathrm{nth}$, or ii) adding effective mass terms derived from the gas momentum equation. We compare these approaches using a numerical replica of the Virgo cluster as a case study, estimating corrected masses from 3D radial profiles in different cluster regions and from projected sightline velocities mimicking XRISM observations. We find that the two methods do not yield the same results in 3D: the non-thermal pressure correction increases the mass by a growing amount with radius (from a few per cent in the core to $\sim$40% at the virial radius), whereas the effective mass terms provide a correction that varies less with radius. When estimated from projections, the two methods agree to within a few per cent for a given sightline, but the non-thermal pressure fraction is underestimated by about a factor of 2 compared to the 3D case. Furthermore, projection effects can change the inferred non-thermal pressure fraction by up to a factor of 2, particularly when the sightline is aligned with
cosmic filaments.
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All authors Théo Lebeau, Nabila Aghanim, Jenny Sorce, Stefano Ettori
Nuclear Theory
Long Time Energy Oscillation Between Electron Shell and Nucleus in $^{229}$Th Ions and Coherent Electron Bridge for Nuclear Quantum Battery
E. V. Tkalya
The electron shell of the Thorium ion with the $M$1(8.4~eV) transition between levels and the doublet of the $^{229}$Th
nucleus ground state with the similar transition represent two
qubits spatially inserted one within the other. In the case of relative proximity of the energies of these transitions, weakly damped energy oscillations can be excited between
qubits, namely, multiple coherent energy transfer from the electron shell to the
nucleus and vice versa. This process in the $^{229}$Th ions does not require resonant (within the width of the levels) coincidence of the transition energies due to the relatively high interaction energy of the electron and
nuclear currents. The electron shell “breathes”, periodically decreasing and increasing in size. The effect can be observed in an ion trap by the intensity of light scattered by thorium-229 ions. This extends the energy range for the $^{229m}$Th$(3/2^+,8.4$~eV) isomer excitation via an electron bridge. Furthermore, the system under consideration is transformed into a
nuclear quantum battery when exposed to coherent
laser radiation. To “charge” the battery, i.e. to excite $^{229m}$Th, one can use developed methods for charging
quantum batteries, in particular, coherent excitation of the electron shell followed by coherent transfer of excitation energy to the
nucleus (the coherent electron bridge). This opens the way for the design of the $^{229}$Th
nuclear quantum battery at the current level of technological development.
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Mesoscale and Nanoscale Physics
Robustness of Quantum Discord in Nonequilibrium Electronic Transport through Tunnel-Coupled Quantum Dots
Thingujam Yaiphalemba Meitei, Saikumar Krithivasan, Md. Manirul Ali et al. (+1 more)
Quantum discord captures
quantum correlations beyond
entanglement and can remain finite even when the
entanglement vanishes. We investigate the transient nonequilibrium dynamics and steady-state behavior of
quantum discord and classical correlations in a double
quantum dot (DQD) system coupled to fermionic reservoirs. By employing a
quantum Langevin equation formalism, we obtain the exact reduced density
matrix of the system, enabling a comprehensive analysis of its
quantum and classical correlations under nonequilibrium conditions. The influence of system-reservoir coupling strength, spectral bandwidth, thermal bias, and varying initial state on both the transient dynamics and steady-state correlations is systematically analyzed.
Quantum discord remains finite in the nonequilibrium steady state over a broad parameter range. Although thermal gradients reduce the overall magnitude of correlations,
quantum discord persists and exhibits greater resilience. These results demonstrate that nonequilibrium electronic transport, together with the environmental spectral properties and reservoir asymmetry, provides an effective means of controlling nonclassical correlations in mesoscopic systems and establishes
quantum discord as a robust hallmark of open fermionic
quantum devices.
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All authors Thingujam Yaiphalemba Meitei, Saikumar Krithivasan, Md. Manirul Ali, Arijit Sen
Quantum Physics
Influence of laser chirp and interferometer delay and imbalance on the performance of a time-bin BB84 quantum key distribution system
Loïc Millet, Alberto Boaron, Rob Thew et al. (+1 more)
We investigate the effect of interferometer delay and imbalance on the performance of a BB84 time-bin
quantum key distribution system. We simulate the impact of interference visibility on system performance and measure the visibility of a pair of interferometers as a function of their relative time delay and intensity imbalance. In addition, our analysis highlights the effect of
laser chirp on system performance.
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All authors Loïc Millet, Alberto Boaron, Rob Thew, Gianluca Boso
Materials Science
Entropy-Driven Structural Phase Transition in Nb$_3$Cl$_8$ via Density Functional Theory and an Effective Model
Chenjie Zhu, Shuai Zhang, Zhong Fang et al. (+3 more)
As a prototypical flat-band cluster Mott
insulator on an effective triangular
lattice, Nb$_3$Cl$_8$ is a potential candidate for hosting a
quantum spin liquid (QSL) state. Nevertheless, a first-order structural phase transition around 90K transforms the high-temperature paramagnetic $\alpha$ phase into the low-temperature nonmagnetic $\beta$ phase, suppressing the candidate QSL regime of the $\alpha$ phase. To clarify the microscopic origin of this transition, we combine first-principles calculations with an extended Hubbard model to construct a unified free-energy framework. This framework reveals that the transition is jointly driven by
phonon and
spin entropy: the $\alpha$ phase is stabilized by softer
phonons and larger paramagnetic
spin entropy, whereas the $\beta$ phase is favored by interlayer dimerization, which hardens the
phonons and quenches the
spin entropy through singlet formation. Furthermore, by evaluating the pressure-dependent generalized enthalpy, we provide a thermodynamic explanation for the suppression of the transition under c-axis uniaxial pressure, where stabilizing the $\alpha$ phase may allow the candidate QSL regime of the $\alpha$ phase to be explored at low temperatures.
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All authors Chenjie Zhu, Shuai Zhang, Zhong Fang, Zhijun Wang, Quansheng Wu, Hongming Weng
Atomic Physics
Nondipole Contributions to Attosecond Chiral Photoionization Asymmetries
Zheming Zhou, Yang Li, Yueming Zhou et al. (+1 more)
Photoelectron circular dichroism (PECD) reads molecular chirality from forward-backward asymmetries in photoelectron emission, but the same observable can also contain non-dipole contributions from
photon momentum transfer. Here we show that such contributions can reshape attosecond PECD measurements in both one- and two-
photon ionization of
chiral molecules. Calculations beyond the dipole approximation, interpreted with perturbation theory, reveal that non-dipole effects modify not only the magnitude but also the phase of the emitted electron wave packet. In two-
photon interferometry, pathway interference amplifies the non-dipole response and can reverse the apparent
chiral asymmetry. We further identify a practical separation principle: the non-dipole component is insensitive to enantiomeric handedness and can therefore be obtained from a racemic mixture. Subtracting this background isolates the purely chirality-induced asymmetry, enabling more accurate measurements of
chiral electron dynamics.
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All authors Zheming Zhou, Yang Li, Yueming Zhou, Peixiang Lu
Exactly Solvable and Integrable Systems
Yangian Doubles and off-Shell Bethe Vectors
A. Liashyk, S. Pakuliak and E. Ragoucy
Off-shell Bethe vectors for a generic $\fg$ invariant integrable model are constructed through the currents of the Yangian doubles of the classical series. These off-shell Bethe vectors are shown to satisfy the defining properties which were used in \cite{LPR-RR} to prove the rectangular recurrence relations and verify the
eigenvalue property of the on-shell Bethe vectors in $\ggo$-invariant integrable models.
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High Energy Physics (Phenomenology)
QCD sum-rule determination of the axial-vector mixing angle in the \texorpdfstring{\(B_c(1P)\)}{Bc(1P)} sector
T.M. Aliev, S. Bilmis and M. Savci
We determine the mixing angle between the \(1^1P_1\) and \(1^3P_1\) axial-vector states in the \(B_c(1P)\) sector using QCD sum rules. The analysis gives \(\theta_{B_c(1P)}=(43.3\pm0.2)^\circ\), indicating sizable mixing between these two states. We also compare our result with theoretical studies available in the literature.
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High Energy Physics (Phenomenology)
The Negative-$\Sigma\bar{\Sigma}$ Angular-Parameter Puzzle in $J/\psi$ and $\psi(2S)$ Decays
Chao-Qiang Geng, Xiang-Nan Jin and Chia-Wei Liu
Experimental measurements of $J/\psi$ and $\psi(2S)$ decays to octet
baryon pairs reveal a negative-$\Sigma\bar{\Sigma}$ puzzle in the angular distributions: $\alpha_\Sigma^{J/\psi}<0$, whereas the other measured $J/\psi$ octet channels and the corresponding $\psi(2S)$ channels have positive angular parameters. We show that an $\mathrm{SU}(3)_F$-exact singlet description is strongly disfavored in a $\chi^2$ fit, giving $\chi^2\simeq 10^5$. By contrast, a reduced scenario in which a common final-state interaction mixes the $\mathrm{S}$- and $\mathrm{D}$-wave amplitudes, with an antisymmetric direct octet and a full diagonal $\mathrm{S}$-$\mathrm{D}$ rescattering block, gives $\chi^2=4.21$ for two nominal degrees of freedom. The negative $\Sigma\bar{\Sigma}$ angular parameter is traced to the pattern of the rescattered $\mathrm{S}$- and $\mathrm{D}$-wave amplitudes. The apparent large $\mathrm{SU}(3)_F$-breaking effect is decomposed into three ingredients: the fitted $\mathrm{D}$-wave source is much larger than the $\mathrm{S}$-wave source, the breaking remains modest when normalized to the $\mathrm{D}$ wave, and $\mathrm{D}\to\mathrm{S}$ rescattering transfers the $\mathrm{SU}(3)_F$-breaking effect from the $\mathrm{D}$ wave into the small $\mathrm{S}$-wave baseline, where it appears large. The largest remaining pull comes from the $\psi(2S)\to N\bar{N}$ angular input, motivating a renewed experimental check of $\psi(2S)\to n\bar{n}$.
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Mathematical Physics · Cross-listed from math.PR
(Non-)Hyperuniformity of Second Order Statistics of Point Processes
Fabio Frommer and Martin Hanke
We investigate statistical properties of certain stationary point processes, namely determinantal processes with projection kernels and Gibbs point processes with superstable pair interactions. These are examples of hyperuniform and non-hyperuniform stationary point processes, respectively. We are interested in the variance of their second order statistics within a ball around the origin, and we study the asymptotic growth of this variance as the radius of the ball goes to infinity. It is shown that, generically, for both types of processes the variance is asymptotically proportional to the volume of the ball. In other words: the second order statistics of these point processes behave non-hyperuniform. For Gibbs processes with superstable interactions these results have an interesting application to the so-called inverse Henderson problem of statistical mechanics. We also show that the structure factor (respectively the Bartlett spectral measure) of these Gibbs processes is strictly positive, while it is positive except for a simple zero at the origin for the determinantal processes.
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Quantum Physics
Open Quantum Systems Driven by Chirped Pulses: Quantized versus Semiclassical Fields and the Validity of the Rotating-Wave Approximation
Justin Zhengjie Tan, Frank Großmann, Yiying Yan et al. (+2 more)
Population transfer via chirped rapid adiabatic passage is studied using open
quantum and semiclassical models, with and without the rotating-wave approximation. A time-dependent variational approach based on the multiple-Davydov D$_2$ trial state is employed to simulate the
quantum models with an arbitrary finite mean
photon number. We examine the accuracy of both the semiclassical field description and the rotating-wave approximation. Robust population transfer is identified over a wide parameter regime controlled by the
laser spectral chirp and is found to be insensitive to the
spin–
phonon coupling strength, Gaussian pulse area, and energy gap of the two-level system.
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All authors Justin Zhengjie Tan, Frank Großmann, Yiying Yan, Maxim Gelin, Yang Zhao
Quantum Physics
Reducing quantum resources for ADAPT-VQE via plateau-operator elimination and correlated mean-field downfolding
Phuoc Minh Vo, Thai Cong Ngoc Vu, Thien Ngoc Tran et al. (+2 more)
Adaptive Derivative-Assembled Problem-Tailored variational
quantum eigensolvers (ADAPT-VQE) represent one of the most promising approaches for
quantum chemistry on near-term
quantum devices. However, their optimization is slow and may stall due to vanishing parameters and redundant operators in the ansatz. In this work, we propose a simple strategy of operator elimination that removes non-contributing operators from the pool once they are detected, enabling the optimization to continue progressing toward convergence. We examine two variants, with and without pool restoration after elimination, and find that the former converges more smoothly and faster than the latter and the standard ADAPT-VQE. To capture dynamical correlations between the active space and its environment, we combine ADAPT-VQE with our recently developed downfolding approach, the one-body downfolding framework (OBDF). In OBDF, the bare molecular
Hamiltonian in the active space is replaced by a correlated effective
Hamiltonian that incorporates dynamical correlation effects outside the active space. We
benchmark our implementation on a linear \ce{H_6} chain, an \ce{H_6}
lattice, an \ce{H_6} ring, and the \ce{N_2} molecule using the OpenFermion simulator. Our results show that operator elimination significantly reduces
circuit depth and iteration count, and that OBDF-ADAPT-VQE yields energies closer to the full configuration interaction (FCI) reference than the standard approach within the same active space.
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All authors Phuoc Minh Vo, Thai Cong Ngoc Vu, Thien Ngoc Tran, Hoang Thanh Nguyen, Lan Nguyen Tran
Quantum Physics
Near-Perfect Single-Photon Source via Ultrastrong Coupling
Ying Ren, Ying-Xue Ma and Jin-Feng Huang
Deterministic single-
photon sources are indispensable core devices for
quantum information technology, yet high-performance implementation remains a long-standing bottleneck for linear optical
quantum computing. We propose a feasible scheme for deterministic single-
photon emission based on a $\triangle$-type three-level atom coupled to a single-mode cavity, driven by two classical external fields, which is adaptable to both strong and ultrastrong cavity-atom coupling regimes. Under continuous-wave driving, the system achieves excellent single-
photon characteristics: the normalized equal-time second-order correlation function reaches $g^{(2)}(0)\sim10^{-6}$, with a
photon indistinguishability of $98.73\%$ and a state purity of $99.95\%$ in the strong coupling regime, while the ultrastrong coupling regime further suppresses $G^{(2)}(0)\sim10^{-8}$, yielding an indistinguishability of $99.10\%$ and a purity of $99.99\%$. For pulsed driving in the ultrastrong coupling regime, the source realizes superior performance, with an emission efficiency, indistinguishability, and purity of $99.96\%$, $98.98\%$, and $99.99\%$ under resonant conditions, and $100\%$, $95.91\%$, and $99.93\%$ under detuned conditions, respectively. The near-ideal optical performance of the proposed scheme provides a viable route for constructing high-quality deterministic single-
photon sources, which offers a promising solution to the limitations of conventional single-
photon devices and facilitates the further development of
quantum information science and fundamental
quantum optical research.
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High Energy Physics (Phenomenology)
Effective Color Dipole Approach to Color Transparency in $\rho^0$ Electroproduction
Tae Keun Choi, Kook-Jin Kong and Byung-Geel Yu
We investigate
nuclear transparency in exclusive $\rho^0$ electroproduction on $^{12}$C and $^{56}$Fe
nuclei within a multi-channel final-state interaction (FSI) framework that explicitly incorporates the kinematic decay length effect (DLE) arising from the short-lived $\rho^0\to\pi^+\pi^-$ decay. The purely kinematic and
nuclear mechanisms prove insufficient to account for the CLAS data: the DLE alone cannot generate the observed $Q^2$-dependent enhancement, and the inclusion of
nuclear shadowing further deepens the disagreement, so that a compensating reduction of the in-medium attenuation – the hallmark of color transparency (CT) – is required. To incorporate the color dynamics of the initially compact $q\bar{q}$ configuration, we replace the empirical
Quantum Diffusion Model (QDM) ansatz for the initial interaction cross section $\sigma_h(Q^2)$ of the point-like configuration (PLC) by an effective Color Dipole Model (CDM) boundary condition, evaluated through a normalized dipole-weighted $\gamma^*\to\rho^0$ transition overlap. Combined with the standard linear QDM transport at an effective in-medium expansion scale $\Delta m^2 = 0.3$~GeV$^2$, the CDM boundary condition reproduces both the magnitude and the $Q^2$ dependence of the data for both targets. A $\chi^2$ analysis quantifies the pronounced separation between the non-CT and CT-based descriptions and thereby supports the onset of color transparency in the $\rho^0$ channel beyond what kinematic decay-length effects can accommodate.
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High Energy Astrophysical Phenomena
Distinct spin properties and astrophysical origin of low mass binary black holes in gravitational wave data
Elizabeth Flanagan, Jakob Stegmann, Isobel Romero-Shaw et al. (+3 more)
We analyze the effective-
spin distribution of binary black hole mergers in GWTC-5.0 as a function of primary black hole mass using hierarchical
Bayesian inference. We model the population as a mixture of two
spin components separated by a transition mass scale inferred directly from the data. We find strong evidence for a transition at $\tilde{m} = 15.2^{+4.3}_{-3.6}\, M_\odot$. Mock-catalog analyses show that such a transition is unlikely to arise from finite-sample fluctuations of a mass-independent $\chi_{\rm eff}$ population and the posterior predictive distributions of $\chi_{\rm eff}$ inferred below and above the transition are clearly distinct. Below the transition mass, the effective-
spin distribution is narrow, peaks at a small positive value $\chi_{\rm eff}>0$, but also shows significant support for negative $\chi_{\rm eff}$. Above the transition, the distribution is broader and its peak shifts to values consistent with $\chi_{\rm eff}\simeq0$, making its support at both positive and negative $\chi_{\rm eff}$ roughly similar. These findings suggest that the dominant merger population concentrated around $10\,M_{\odot}$ is statistically distinct from the rest and that it arises from a different formation channel. We show that this low-mass population is broadly consistent with formation from massive
stellar multiples in the field: it may either arise from isolated binary
star evolution but only if black hole natal kicks below $\tilde{m}$ are generally very large ($\gtrsim100\,\rm km/s$) or be caused by the dynamical
evolution of hierarchical triples. In contrast, isolated binary
evolution with standard fallback kick models cannot reproduce the support for negative $\chi_{\rm eff}$.
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All authors Elizabeth Flanagan, Jakob Stegmann, Isobel Romero-Shaw, Thomas Callister, Aleksandra Olejak, Fabio Antonini
Lattice Field Theory
Isospin-breaking effects in inclusive hadronic $\tau$ data for the muon $(g-2)$ from first principles
Mattia Bruno, Taku Izubuchi, Christoph Lehner et al. (+3 more)
The knowledge of isospin-breaking effects in hadronic $\tau$ decays is required for a high-precision determination of the Hadronic-
Vacuum-Polarization contribution to $(g-2)_\mu$ from experimental $\tau$ data. In this work we present a strategy for their calculation in a fully inclusive setup from first-principles
Lattice QCD+QED simulations. We separate radiative corrections in three infrared safe classes, which we study individually. We provide analytic expressions for their effects in the initial state and propose a strategy for final-state corrections directly in Euclidean space. We also examine the non-factorizable contributions and highlight the challenges associated with their analytic continuation from Euclidean to Minkowski space. By studying short-distance corrections in the context of momentum schemes, we provide a prescription for the renormalization of the individual terms at first order in the ispospin-breaking parameters.
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All authors Mattia Bruno, Taku Izubuchi, Christoph Lehner, Aaron S. Meyer, Julian Parrino, Xin-Yu Tuo
General Relativity and Quantum Cosmology
Relaxation without ringdown for a compact object in modified gravity
Gianmassimo Tasinato
Compact objects with black-hole-like exteriors may hide new strong-field physics in their interiors, making their dynamical response a sensitive probe of
gravity beyond General Relativity. We present an analytically tractable, gravitationally bound compact object with a genuinely new dynamical signature: under a minimal passive boundary prescription, its exactly controlled odd-parity sector exhibits purely dissipative relaxation poles, rather than the oscillatory modes usually associated with black holes and exotic compact alternatives. The object we study is a regular, vector-supported compact solution of a vector–tensor theory, matched without any surface layer to an exterior Schwarzschild geometry. Owing to its anisotropic stress, it can violate the Buchdahl bound and be continuously connected to the black-hole compactness limit. Its unusual response follows from a hidden
chiral symmetry, which turns the perturbation problem into one-way transport rather than ordinary wave propagation. The exterior region alone has no conventional quasinormal-mode spectrum; instead, the regular interior and the matching conditions break the
symmetry and quantize the fluctuation spectrum. We analytically compute the retarded Green function and susceptibility, and derive an effective membrane response by integrating out the object's interior. In the black-hole limit, the relaxation times diverge, the poles collapse toward zero frequency, and finite-frequency exterior perturbations decouple from the interior. Black-hole behaviour is therefore approached through the disappearance of relaxation modes, not through the emergence of ringdown.
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Quantum Physics
Configuration-based understanding of superradiant phase transitions in Dicke lattices
Peng-Fei Wei and Zhihai Wang
The emergence of multiple superradiant phases in Dicke
lattice models has attracted considerable
attention in the
quantum optics community. However, a unified understanding of the origin of multistability and its relation to different superradiant phases is still lacking. Here, we develop a configuration-based understanding to classify the superradiant phases in Dicke
lattices. We show that
photon hopping naturally organizes the possible superradiant configurations according to the
lattice symmetry, providing a unified interpretation of the nonequilibrium phase diagram and the emergence of multistability. For the dissipative four-site Dicke
lattice, we obtain the complete phase diagram and identify the coexistence of up to four stable superradiant phases. The proposed classification is further extended to five- and six-site
lattices. Moreover, we demonstrate that the same configuration-based understanding also applies to the closed Dicke
lattice, where the ground state uniquely selects one of the allowed configurations. Finally, we show that different configurations may belong to either same or distinct nonequilibrium universality classes in the dissipative Dicke
lattice, while they share the same
equilibrium universality class in the closed Dicke
lattice. Our results provide a unified picture for understanding
equilibrium and nonequilibrium superradiant phase transitions in Dicke
lattices.
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Atomic Physics
Nuclear-size correction to the one-loop self-energy in hydrogenlike ions
Ping Yang, Aleksei V. Malyshev, Aleksandr N. Kochnev et al. (+4 more)
The
nuclear-size effect on both diagonal and off-diagonal one-loop self-energy
matrix elements is considered for hydrogenlike ions with $Z=60$, $82$, $90$, and $92$. Specifically, the $1s$, $2s$, $3s$, $2p_{1/2}$, and $2p_{3/2}$ states, as well as the off-diagonal $1s-2s$, $1s-3s$, and $2s-3s$
matrix elements are considered. The calculations are performed within the rigorous
quantum-electrodynamics framework, nonperturbatively in the
nuclear-strength parameter $\alpha Z$. Excellent agreement is found with results reported in the literature. Simple and useful approximate formulas to treat the
nuclear-size correction are obtained, which, in particular, can be used to study the self-energy contributions to the field-shift factors.
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All authors Ping Yang, Aleksei V. Malyshev, Aleksandr N. Kochnev, Vladimir M. Shabaev, Aleksandr S. Shamanaev, Ting-Yun Shi, Dmitry V. Sychkov
Earth and Planetary Astrophysics
Relativistic Time Scales and Transformations in the Solar System
Hong-Bo Jin, Jinsong Ping, Min Liu et al. (+1 more)
Each
solar-system observable is characterised by celestial reference system (CRS) coordinate time, proper time on its world line, and the transformation between them. Ephemerides and Deep Space Network (DSN) tracking use the International Astronomical Union (IAU) barycentric and body-centric hierarchy, now extended to cislunar and Mars work. The IERS Conventions, Moyer radiometric models, and recent lunar-time papers distribute metric, scale, and tracking formulae across separate manuals. Merged Chang'e- or Tianwen-class data can acquire microsecond-level range and Doppler biases unless proper time $\tau$ is mapped consistently to barycentric and body-centric coordinate times. We present a unified 1PN documentation chain: tabulated harmonic Christoffel symbols through $\mathcal{O}(c^{-4})$, the barycentric-geocentric-terrestrial coordinate-time sequence,
Fermi normal coordinates, null-geodesic observables, and a 1PN two-way range-rate expansion, applied in parallel to Mars (MCRS/MCG) and lunar (LCRS/TCL) body-centric systems. The chain yields a Mars areoid-geoid metric clock-rate difference of $\sim$48~$\mu$s\,day$^{-1}$ and lunar selenoid-geoid rates of $\sim$57.4-58.7~$\mu$s\,day$^{-1}$ consistent with published nested coefficients. Mars-range Shapiro-rate terms reach $10^{-12}$-$10^{-13}$. Multi-CRS consistency relies on documented transformation chains rather than a single master clock.
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All authors Hong-Bo Jin, Jinsong Ping, Min Liu, Mingyuan Wang