High Energy Physics (Experiment)
Sensitivity of a Missing-Mass Search for a Light Dark Photon with a Positron Beam on a Hydrogen Target
Weizhi Xiong, Ashot Gasparian and Bogdan Wojtsekhowski
We present a Geant4-based simulation study of the sensitivity to a light dark
photon, $A'$, using a positron beam incident on a thin
liquid-hydrogen target and a high-resolution forward electromagnetic calorimeter for final-state
photon reconstruction. This study is motivated by ongoing research and development toward a low-energy positron facility at Jefferson Lab. The proposed search employs the missing-mass technique in the annihilation-in-flight process $e^+e^- \to \gamma A'$, providing sensitivity to the $A'$ independently of its decay mode. We evaluate the expected backgrounds from standard QED annihilation and bremsstrahlung processes and present the projected sensitivity to the kinetic-mixing parameter $\epsilon^2$ as a function of the $A'$ mass. The experiment with 500~MeV beam will provide the data for $A'$ mass range 7-19 MeV. The projected sensitivity on $\epsilon^2$ is $4\times10^{-8}$ at $m_{A'}=19$~MeV.
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Superconductivity
Topological pair density waves in kagome superconductors
Jia-Xin Yin, Xianxin Wu, Mark H. Fischer et al. (+3 more)
The pair density wave (PDW) is an unconventional superconducting state exhibiting periodic pairing modulations due to pairing with finite momentum Q. In two dimensions, multiple Q components of the PDW can have a non-trivial relative phase, breaking time-reversal
symmetry and resulting in a topological electronic structure. Here we review progress on exploring such topological PDWs (TPDWs) and discuss their potential realization in kagome
superconductors. We first introduce the concept of a TPDW starting from the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state and examine the challenges toward its realization. We then discuss the possibility of a TPDW in the kagome
lattice, which intertwines with
chiral superconductivity and loop currents, thus connecting to models describing the
quantum anomalous
Hall effect. Furthermore, we review the experimental signatures of a TPDW in AV3Sb5 (A = Cs, Rb, K)
superconductors and highlight related
quantum effects, including switchable
chiral pairing modulations, Bogoliubov
Fermi states, the superconducting diode effect, and the anomalous thermal
Hall effect. Finally, we project the future research opportunities of this correlated topological
quantum phase and discuss its broad implications for finite-momentum pairing, topological matter, and
chiral superconductivity.
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All authors Jia-Xin Yin, Xianxin Wu, Mark H. Fischer, Xiao-Yu Yan, Yigui Zhong, Kozo Okazaki
Strongly Correlated Electrons
Evolving charge order in the CDW state of AV$_3$Sb$_5$ metals
Anshu Kataria, Francis Pratt, Peter J. Baker et al. (+7 more)
AV$_3$Sb$_5$ kagome metals are characterized by intertwined electronic and structural orders, which motivated extensive studies in recent years. Yet the details of the electronic state preceding the superconducting phase remain poorly understood. Here we extend our previous investigation [Phys. Rev. Research 7, L032046 (2025)] of RbV$_3$Sb$_5$ using avoided level crossing (ALC)
muon-
spin spectroscopy to the $A$ = Cs and K systems. Consistent with our previous study, we identify a second transition whose origin cannot be attributed solely to an internal
magnetic field, indicating the involvement of an additional electronic mechanism that subtly modifies the charge distribution within the V plane. In particular, the ALC results point towards an additional charge modulation taking place within the charge density wave (CDW) phase and occurring at $T^{*}<T_{CDW}$ for $A$ = Cs and Rb, or in the vicinity of $T_{CDW}$ for $A$ = K.
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All authors Anshu Kataria, Francis Pratt, Peter J. Baker, Stephen Cottrell, Miki Bonacci, Andrea Capa Salinas, Stephen D. Wilson, Zurab Guguchia, Samuele Sanna, Pietro Bonfà
Materials Science
Directional commensurability stabilizes structural superlubricity in patterned mesoscale interfaces
Viet Hung Ho, Ge Li, Melisa M. Gianetti et al. (+3 more)
Structural superlubricity, arising from
lattice incommensurability, offers a promising route to eliminate friction and associated energy losses in mechanical systems. In real-world systems, roughness and wear currently pose severe limitations on its robustness and especially the contact size. Here, we consider patterned surfaces as a possible route to overcome some of these limitations. We show that the simplest choice of patterning, contacts made up of two incommensurate triangular-triangular patterns, fails at elevated loads because of the small number of load-bearing contacts, causing the maximum local contact pressure to exceed the strength of the superlubric coating. We introduce a square-triangular patterned interface that increases the number of load-bearing contacts and organizes them into continuous contact lines. When sliding along specific directions relative to these lines, superlubricity is maintained at significantly higher loads by reducing pressure-induced coating failure while also remaining somewhat tolerant to surface imperfections. These findings establish a mechanism for stabilizing structural superlubricity against coating failure and a design principle for engineering low-friction interfaces with enhanced load-bearing capacity and defect tolerance.
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All authors Viet Hung Ho, Ge Li, Melisa M. Gianetti, Bjørn Haugen, Graham L. W. Cross, Astrid S. de Wijn
Earth and Planetary Astrophysics
Dynamical Mass Demography of Single S-type Planets Shaped by Stellar Companions
Xiumin Huang and Jianghui Ji
More than 700 S-type
planets have been identified from
Gaia and TESS observations, including over 150 transiting targets, enabling the precise dynamical orbits and planetary mass characterization in binary environments. Here we present the first systematic N-body dynamical mass determination for 40 single S-type (Satellite-type orbit)
planets in close binaries using an improved Markov Chain Monte Carlo (MCMC) framework with Gaussian priors to model
stellar companion perturbations. {For binary systems with $a_\mathrm{B}<100$ au, companion-induced perturbations can bias the RV semi-amplitude and consequently the inferred planetary masses. The impact is strongest for short-period sub-Jovian
planets, whose masses decrease by up to 20% when transitioning from Keplerian to N-body modeling, while massive Jovian
planets with $M_{\mathrm{Jup}} < M_{\mathrm{p}} < 5$ $M_{\mathrm{Jup}}$ show only a 7.2% reduction.} Applying the NAFF stability criterion to TOI-4633, $i_{\mathrm{mut}} = 70^{\circ}$ is the upper limit for the fast rejection of unstable orbital solutions. Our results reveal that intermediate-mass
planets exhibit both positive or negative biases in the inferred masses and influence the observed population of the sub-Jovian desert.
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High Energy Physics (Phenomenology)
Higgs boson pair production in SMEFT: shape and truncation studies
Manosch Bär, Bakar Chargeishvili, Ramona Gröber et al. (+2 more)
We present a comparative study of the influence of Wilson coefficients on
Higgs boson pair production cross sections in SMEFT up to dimension-6, also including loop-suppressed operators. Our study accounts for NLO QCD corrections, and is based on updated parametrizations of the cross section as a
polynomial in the Wilson coefficients. We focus on differential distributions for the
Higgs boson pair invariant mass, as well as the transverse momenta of the leading
Higgs bosons, identifying
benchmark scenarios exhibiting pronounced shape distortions in the $m_{hh}$ and $p_{T,h}$ distributions. While some of these scenarios remain physically meaningful under a purely linear truncation of the SMEFT expansion, others yield unphysical differential cross sections when quadratic dimension-6 contributions are omitted, exposing the breakdown of the linear approximation for large anomalous couplings.
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All authors Manosch Bär, Bakar Chargeishvili, Ramona Gröber, Gudrun Heinrich, Konstantin Schmid
Soft Condensed Matter
A route to the thermodynamics of colloid-polymer mixtures from structural information
Vikki Anand Varma, Andrew J. Archer and Alberto Scacchi
Liquid-state theory provides a fundamental connection between microscopic structure and macroscopic thermodynamic behaviour. Here, we develop a framework for predicting thermodynamics and phase behaviour directly from structural correlations, using either radial distribution functions or static structure factors as input. The approach constructs a free-energy functional from structural information obtained at a single thermodynamic state point, without requiring explicit knowledge of the underlying interaction potentials. This circumvents a central difficulty in modelling complex fluids, for which effective interactions are often unknown or rely on approximations. We demonstrate the framework for a range of model fluids, including colloidal and colloid–
polymer systems, with predictions in good agreement with molecular simulation data. The results show that structural information at a single state point can provide sufficient information to predict the broader thermodynamic response of a system. This establishes a route toward inferring phase behaviour directly from experimentally measured structure, even when the microscopic interactions are not known a priori.
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Statistical Mechanics
Light-induced nonconservative static forces in many-body systems
Jinze Li, Xuemei Yang and Zhiyuan Sun
In a
quantum many-body system, a periodic drive can often generate effective static forces on the slow collective degrees of freedom. We study the static forces generated by light on electronic order parameters in solid-state systems. We show that the forces can have nonconservative components that originate from dissipation, i.e., optical absorption. This effect is demonstrated in two nontrivial examples. In excitonic
insulators, via interband excitations, the light field generates a nonconservative force on the phase of the excitonic order parameter. This force leads to an acceleration of the phase, which manifests as a shift of the
photon emission peak from an
exciton condensate. In materials with an incommensurate charge density wave, a propagating light field generates a nonconservative force on the phase of its order parameter. It drives the charge density wave into sliding motion, leading to a DC electric current via topological Thouless pumping.
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Strongly Correlated Electrons
Electronic phase separation and emergence of a nondimerized insulating phase in VO$_2$ $(110)_{\mathit{R}}$ ultrathin films
S. Inoue, D. Shiga, R. Hayasaka et al. (+3 more)
Using in situ photoemission spectroscopy and x-ray absorption spectroscopy, we investigated the thickness dependence of the electronic structure and V-V dimerization in VO$_2$/TiO$_2$ (110) ultrathin films, in which the one-dimensional V-V chains along the $c_{\mathit{R}}$ axis lie in the film plane. In VO$_2$ $(110)_{\mathit{R}}$ films, the reduction in dimensionality along the surface-normal direction is not expected to impose a
geometric constraint on V-V dimerization, unlike in VO$_2$ $(001)_{\mathit{R}}$ films. Nevertheless, the characteristic spectral changes associated with the temperature-driven metal-
insulator transition observed in thick films persist down to 1.5 nm, whereas at 1 nm an insulating electronic phase is observed without V-V dimerization. This behavior is highly similar to that reported for VO$_2$ $(001)_{\mathit{R}}$, suggesting that the enhancement of Mott instability resulting from reduced dimensionality is a common and essential driving force for the emergence of the nondimerized insulating phase in VO$_2$ ultrathin films. Meanwhile, unlike in VO$_2$ $(001)_{\mathit{R}}$, the nondimerized insulating phase in VO$_2$ $(110)_{\mathit{R}}$ coexists with the phase exhibiting the temperature-driven metal-
insulator transition. Its fraction increases exponentially with decreasing thickness and becomes dominant at 1 nm. The corresponding effective critical thickness is estimated to be 2.2 nm. These results imply that the
geometric orientation of the V-V chains dictates the spatial
evolution of electronic phase separation via strain-mediated phase competition.
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All authors S. Inoue, D. Shiga, R. Hayasaka, K. Ozawa, A. F. Santander-Syro, H. Kumigashira
General Relativity and Quantum Cosmology
Exact dynamics and the spin wall for large-spin particles in Schwarzschild spacetime
Chao-Jun Feng and Rui-Hui Lin
The motion of a spinning test particle in a curved spacetime is governed by the Mathisson–Papapetrou–Dixon (MPD) equations and deviates from geodesic motion already at first order in the
spin. While essentially all existing studies truncate the dynamics at linear order in the
spin, we present an exact, nonperturbative treatment of planar motion in Schwarzschild spacetime under the Tulczyjew–Dixon
spin supplementary condition: eliminating the four-velocity recasts the MPD system into a closed algebraic form and reduces the radial motion to an effective-potential problem, with no expansion in the
spin at any stage. This exact framework uncovers qualitative features that are absent from—and in fact unattainable within—the linearized description. Most notably, for sufficiently large
spin the effective potential develops a double root at a characteristic radius determined solely by the particle mass and
spin, marking an impenetrable
spin wall of purely
spin origin; beyond a critical
spin the wall lies outside the event horizon and shields it from generic infalling particles. Moreover, the wall is a filter for particle: only orbits with a specific combinations of
spin, angular momentum and energy can penetrate it, all others being reflected before reaching the horizon. In addition, the innermost stable circular orbit, which in linear treatments merely shifts continuously with
spin, is obtained in closed form in the weak-field limit and is shown to cease to exist at sufficiently large
spin. We further compute the
spin correction to the perihelion precession in the weak-field limit and verify that all results reduce to the standard ones at vanishing
spin. The
spin wall and its filtering rule are genuine nonperturbative phenomena, invisible to any finite-order expansion in the
spin, with potential observational signatures in
accretion flows around compact objects.
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General Relativity and Quantum Cosmology
Schwarzschild spectral ladders on the negative imaginary axis: Endpoint nonselection, branch-cut phase, and Jost classification
Davide Batic, Denys Dutykh and Mark Essa Sukaiti
Compactified spectral discretisations may yield stable negative-imaginary-axis (NIA)
eigenvalue ladders, but finite-
matrix convergence does not establish quasinormal poles. For axial Schwarzschild perturbations, ingoing–outgoing factorisation leaves an unwanted horizon solution behaving as $t^{4\alpha}$ at $\Omega=-i\alpha$, and a $C^\infty$-flat unwanted infinity solution. Thus endpoint $C^k$ regularity is nonselective for $4\alpha>k$, so the $C^2$ continuum problem cannot have a discrete NIA spectrum over $\alpha\simeq15$–32. Exact Chebyshev-grid formulas give roots-grid maximum radius $O(n^{2p})$ for $x\sim C(1-y)^{-p}$, explaining C1, $x=2/(1-y)$, versus C2, $x=4/(1-y)^2$. Arbitrary-precision pencils nevertheless reveal a reproducible 68-point C1 ladder, while C2 reorganises it. Both physical lateral Jost determinants remain stably nonzero at every C1 frequency. A 0.05-spaced on-cut scan finds no zero, and refined argument-principle calculations give zero winding in both continuation strips. This rejects all 68 candidates, although the mesh and strip evidence is not interval-certified. Same-damping controls recover Schwarzschild QNMs $n=60,100,130$, with $|\widehat{\mathcal D}|=10^{-48}$–$10^{-56}$. The ladder has surface-
gravity quarter spacing, follows the parameter-free Casals–Ottewill branch-cut-strength phase, and pairs with damping projections of QNMs $n=62,\ldots,129$. At its first member, a finite-frequency calculation finds a branch-strength zero at $\alpha_q=15.07832396512359$, between the asymptotic prediction and the C1 root, supporting, but not proving, sequence-wide cut-phase locking. Thus accurate finite-pencil
eigenvalues can fail the invariant Jost/Evans pole criterion. Whether representation-dependent nodes with Keldysh weights converge collectively to the Schwarzschild cut response and Price tail remains open.
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Superconductivity
Doping-driven evolution of pairing symmetry in pressurized La$_3$Ni$_2$O$_7$
Hai-Yang Zhang, Yu-Jie Bai and Fan-Jie Kong
We investigate the superconducting pairing
symmetry and its doping
evolution in pressurized La$_3$Ni$_2$O$_7$. For the undoped compound, the most favorable pairing state is found to be $s_{\pm}$-wave, characterized by sign reversal of the gap functions between the
Fermi pockets. A detailed analysis of the pairing interactions reveals that this unconventional state originates from repulsive interactions mediated by the
magnetic odd modes of the
bilayer nickelate. Upon hole doping, the $\gamma$
Fermi pocket expands, which amplifies the intrapocket repulsions on this pocket. These repulsions, driven by the
magnetic even modes, gradually dominates the pairing interactions and ultimately drive a transition in pairing
symmetry from $s_{\pm}$-wave to $d_{xy}$-wave in the heavily hole-doped regime. In stark contrast, the $s_{\pm}$-wave pairing persists under electron doping, even deep into the heavily electron-doped regime where a Lifshitz transition occurs. This finding suggests that the $\gamma$
Fermi pocket is not essential for the emergence of superconductivity in
bilayer nickelates. In fact, the $s_{\pm}$-wave pairing becomes more robust in the absence of the $\gamma$ pocket, as
spin fluctuations are strongly enhanced by the favorable nesting between the $\alpha$ and $\beta$ pockets — a condition guaranteed by Luttinger's
theorem and the
Fermi surface
topology. We believe that exploring the doping
evolution of superconducting pairing will open a new realm for testing the pairing mechanism in pressurized La$_3$Ni$_2$O$_7$.
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Lattice Field Theory
Detecting Multiple Phase Transitions in Lattice Systems with Intrinsic Dimensions
Jie Mei, Tetsuo Hatsuda, Mei Huang et al. (+1 more)
Lattice systems with multiple nearby transitions pose two related challenges: resolving distinct transition scales and identifying the degrees of freedom primarily associated with each transition. We show that the intrinsic dimension of Monte Carlo configuration ensembles, estimated by the two-nearest-neighbors method, provides a
geometric diagnostic for both problems. In the two-dimensional $q$-state clock model, the intrinsic dimension distinguishes the ordered, quasi-critical, and disordered regimes for both well-separated ($q=9$) and closely spaced ($q=5$) Berezinskii–Kosterlitz–Thouless transitions. In the $q=5$ case, the intermediate phase appears as a broad low-dimensional valley even when energy and magnetization do not separately resolve the two transitions. In the four-dimensional $U(1)$
Higgs model, we introduce channel-decomposed intrinsic dimensions based on gauge-invariant plaquette and
Higgs variables. The dominant response of each channel tracks transitions associated with the corresponding degrees of freedom, while the combined channel retains features of both. We further show that intrinsic dimensions evaluated directly on gauge-variant fields are dominated by gauge-orbit directions, demonstrating the importance of removing gauge redundancy before interpreting configuration-space geometry. These results establish channel-decomposed intrinsic dimension as a
geometric probe of
lattice systems with multiple transitions and motivate its application to disentangling deconfinement and
chiral crossover scales in full QCD.
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All authors Jie Mei, Tetsuo Hatsuda, Mei Huang, Lingxiao Wang
Strongly Correlated Electrons
Real-space manifestation of ferroic multipoles in altermagnetic MnF$_2$
Iurii Kibalin, Dalila Bounoua, José A. Rodriguez Velamazán et al. (+9 more)
Altermagnets are unconventional
spin split magnets arising from the zero
spin-orbit coupled limit. They host a
magnetic multipolar order parameter yet direct real-space observation of these multipoles has remained elusive. Here we use polarized-
neutron diffraction to reconstruct the three-dimensional magnetization density of the prototypical altermagnet MnF$_2$. By exploiting
symmetry-selective
magnetic reflections, we separate the dominant spherical Mn$^{2+}$ contribution from the much weaker anisotropic Mn magnetization and the covalent
spin polarization of the fluorine ligands. The reconstructed
spin density reveals a finite fluorine ion moment together with an anisotropic Mn magnetization consistent with the
symmetry-allowed altermagnetic rank-5
magnetic multipole $O_{52}$(
magnetic triacontadipole). These results provide direct real-space evidence of ferroic multipolar order in an altermagnet and establish polarized-
neutron diffraction as a powerful probe of hidden
magnetic multipoles in
quantum materials.
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All authors Iurii Kibalin, Dalila Bounoua, José A. Rodriguez Velamazán, Oscar Fabelo, Navid Qureshi, Quentin Faure, Philippe Bourges, Victor Balédent, Jian-Rui Soh, Jeffrey Rau, Paul McClarty, Arsen Gukasov
Quantum Physics
Quantum discord of Gaussian states in non-inertial frames
Siwei Li and Xiaofen Huang
We investigate the redistribution of continuous-variable Gaussian
quantum discord under the Unruh effect for both one and two uniformly accelerated observers. The discord shared between the inertial mode and the accessible accelerated mode, as well as that between the two accessible accelerated modes, decays monotonically with acceleration and vanishes in the limit $a\to\infty$, while the Unruh effect generates discord in all causally disconnected Rindler mode pairs. The initial
quantum correlation is therefore redistributed across Rindler partitions rather than destroyed. We further characterize how the squeezing parameter $s$ and field frequency $\omega$ control the discord in different mode-pair classes. For causally connected pairs, $s$ and $\omega$ exert comparable, interchangeable effects; for cross-region pairs, the squeezing parameter dominates; and for intra-observer cross-region pairs, the field frequency is more influential. In the two-observer case, the $A_{II}$-$B_{II}$ pair exhibits non-monotonic behavior with a peak whose position shifts to larger $a$ as $\omega$ increases, and both parameters contribute only weakly except near an optimal $\frac{\omega}{s}$ ratio.
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High Energy Physics (Experiment)
A Pythia8 Tune for Open Charm and Beauty Production in Fixed-Target Collisions
Matei Climescu, Didar Dobur and Kirill Skovpen
We present FTFT (Fixed-Target Fragmentation Tune), a set of Pythia8 parameters optimised for the production of charm and beauty
hadrons in fixed-target collisions at centre-of-mass energies $\sqrt{s} \simeq 20-42$ GeV. Accurate heavy-flavour production in this regime is needed to predict
neutrino fluxes and hidden-particle yields at beam-dump experiments such as SHiP. The tune is derived in two stages. First, differential distributions in Feynman-$x$ ($x_F$), transverse momentum squared ($p_T^2$), and charge or leading-particle production asymmetry of $D$
mesons are fitted to data from pion- and
proton-beam fixed-target experiments. Second, $K$-factors for each beam are extracted from inclusive charm cross-section measurements to scale the simulated cross section to the measured data. The fitted charm-fragmentation and multiparton-interaction parameters depart from standard LHC-tuned defaults, in line with earlier fixed-target studies.
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High Energy Astrophysical Phenomena
Evidence for an accretion-driven subpopulation of black holes in GWTC-5.0
Zacharias Roupas
We report
Bayesian evidence for a subpopulation of black holes, grown via
accretion during the gaseous birth-stage of
star clusters, in the cumulative GWTC-5.0 released by the LIGO-Virgo-KAGRA collaboration. This
accretion channel predicts a saturating
spin–mass relation, with low
spins at low masses, rising continuously with mass through all intermediate
spin values, to high
spins at high masses. We test this prediction directly against the component
spins of the catalogue. We single out 10 events with positive support and many others with weaker support across the whole component-mass range of the catalogue. We identify a preferred mass scale $m^t=20.7^{+11.6}_{-1.2}\,M_\odot$ (90% credibility) separating regimes with different
accretion-mixture fractions, with $\ln B=5.5$. Above this inferred scale, the evidence for an
accretion-driven subpopulation is strongly concentrated, reaching a natural log Bayes factor of $16.6$ against the LVK fiducial
spin population.
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Fluid Dynamics
Spectral-Embedded Operator Learning for Three-Phase Interfacial Flow: A Ternary Cahn-Hilliard-Navier-Stokes Benchmark
Muhammad Abid, Arth Sojitra and Omer San
Operator-learning surrogates have been benchmarked largely on single-field, single-interface problems, leaving unclear whether architectural choices validated in those settings transfer to constrained, multiphase flows. We introduce a three-phase interfacial-flow
benchmark to examine whether the trunk coordinate representation matters for a multi-channel, interface-dominated target. The configuration consists of an air bubble rising through water, piercing a water-oil interface, and entraining a water plume into the oil within a bounded, wall-confined domain. Reference data are generated using a structure-preserving ternary Cahn-Hilliard-Navier-Stokes solver that algebraically preserves the simplex constraint. From 1,024 Sobol-sampled simulations spanning a nine-dimensional parameter space, we learn the mapping from physical parameters to five-channel space-time fields. We compare three parameter-matched DeepONet variants differing only in trunk representation: raw coordinates (DeepONet), random
Fourier features (FEDONet), and a fixed tensor-product Chebyshev dictionary (SEDONet). SEDONet reduces the test relative L2 error by 16.8% compared with FEDONet and by 24.0% compared with DeepONet, while improving all five output channels. Spatial and temporal error analyses localize the principal gains near the diffuse interfaces and after bubble breakthrough. The results indicate that the Chebyshev representation is particularly effective for the strongly non-periodic wall-normal and temporal structure of this three-phase flow.
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Quantum Physics
The Inverse Eigenvalue Problem for Partial Transposes of Two-Qubit States
Ruoting Dou, Shengjun Wu and Zeng-Bing Chen
For a bipartite state $\rho$, information about the spectrum of its partial transpose $\rho^{\Gamma_B}$ can be inferred from measurements on multiple copies of $\rho$, without full state
tomography. This raises a natural question: which
eigenvalue lists can arise as $\operatorname{spec}(\rho^{\Gamma_B})$ for a density operator $\rho$? We completely solve this inverse
eigenvalue problem for two
qubits. Every nonnegative trace-one spectrum is realized as $\operatorname{spec}(\rho^{\Gamma_B})$ by some PPT state $\rho$, whereas an ordered candidate
eigenvalue list $(x,y,z,-q)$, with $x\ge y\ge z\ge0$, $q>0$, and $x+y+z-q=1$, is realized by an NPT state iff $q\le y$ and $qy\le xz$. Sufficiency in the latter case is established by an explicit $X$ state whose
quantum steering ellipsoid has center $c=(y-q)/(1-z)$ and normalized volume $V/V_{\max}(c)=qy/(xz)$, providing a
geometric interpretation of the inequalities $q\le y$ and $qy\le xz$ as the allowed ellipsoid-center region and the fixed-center volume bound. Beyond this
geometric picture, the two-
qubit inverse
theorem also yields exact negativity bounds from the two lowest nontrivial PT moments. Given fixed values of $p_2=Tr[(\rho^{\Gamma_B})^2]$ and $p_3=Tr[(\rho^{\Gamma_B})^3]$, we determine the exact minimum and maximum negativity over all two-
qubit states subject to these moment constraints. When no PPT state is consistent with the pair $(p_2,p_3)$, the minimum is attained either at $x=y$ or $qy=xz$, while the maximum is attained either at $y=z$ or $q=y$. Finally, we show how the two-
qubit inequalities persist as necessary constraints for the inverse
eigenvalue problem in
qubit–qudit systems.
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Mathematical Physics · Cross-listed from math.AG
All genus open mirror symmetry for footballs
Zhuoming Lan, Jinghao Yu and Zhengyu Zong
We prove an all genus full descendant open mirror
symmetry for footballs. The B-model is given by the Chekhov-Eynard-Orantin topological recursion on the mirror curve.
Strongly Correlated Electrons
Duality Between Twist-Angle Disorder and Non-Hermitian Disorder
Yi-Ming Wu and Nicole S. Ticea
We propose and study a model of moire heterobilayer systems where the twist angle remains uniform and well defined only within a finite range, but deforms randomly at larger distances. The local twist angle is then subject to a certain probability distribution that penalizes large fluctuations around its mean value. Within the framework of the replica trick, we show that disorder averaging produces a nontrivial correlation with alternating sign between replicas, maximized only close the boundary of each local domain and along certain directions. We show that for the low-energy moire bands, exactly the same correlation can be generated in a dual model where
fermions are coupled to non-Hermitian disorder, which can evade Anderson localization dynamically. This duality provides a new perspective to investigate twist-angle disorder in moire systems, and unveils some of the essential differences between twist-angle disorder and conventional disorder.
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Strongly Correlated Electrons
Enhanced Diffusion from Twist-Angle Disorder
Nicole S Ticea and Yi-Ming Wu
We consider the effect of twist-angle disorder on the single-particle properties of twisted
bilayer systems. These materials are a natural playground for studying how tiny, uncontrolled spatial variations may become unusually consequential; a local change in the twist geometry can give rise to spatially-correlated alterations of the parent
Hamiltonian, which in turn affect the coarse-grained properties of the substrate such as transport and ordering tendencies. In analogy to electrodynamics, where the
magnetic field is given by the curl of the vector potential, we model the twist angle as the curl of the relative displacement between the two
bilayers. We find that
geometric scattering constraints imposed here by the twist structure substantially suppress momentum relaxation relative to mean-rate-matched white noise. We quantify these effects and show that the problem can be mapped onto a non-linear sigma model (NLSM).
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Cosmology and Nongalactic Astrophysics
Primordial black holes and induced gravitational waves from localized features in DBI inflation
Narges Rashidi
We investigate
primordial black hole formation in a Dirac-Born-Infeld inflationary framework in which the background dynamics are determined by explicit functional forms of the inflaton potential $V(\phi)$ and the warp factor $f(\phi)$. The background equations are solved numerically to obtain the
evolution of the slow-roll parameters. We show that a localized feature in the potential, accompanied by a correlated structure in the warp factor, dynamically induces a transient suppression of the slow-roll parameter, leading to a short-lived non-attractor phase. This behavior generates an enhancement of the
curvature power spectrum on small scales, while preserving consistency with CMB-scale observables. The Mukhanov-Sasaki equation is then solved numerically to compute the resulting power spectrum, which exhibits narrow and localized peaks in the PBH abundance across different mass ranges. We also evaluate the associated
stochastic background of induced gravitational waves and find that the predicted signal can fall within the sensitivity bands of future
pulsar timing arrays and space-based interferometers, depending on the scale of the inflationary feature. A parameter scan in the $(r,n_s)$ plane shows that the large-scale predictions remain consistent with current observational constraints.
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High Energy Physics (Phenomenology)
Taming lepton portal dark matter by a non-invertible selection rule
Junichiro Kawamura
We point out that a non-invertible selection rule can control the
flavor violation inherent in
lepton portal dark matter, a weakly interacting massive particle candidate that can evade severe constraints from direct detection experiments. We show that ordinary invertible
symmetries cannot suppress
flavor-violating portal couplings while accommodating the large mixing angles in the PMNS
matrix. We then present a simple construction based on the $\mathbb{Z}_2$ gauging of a $\mathbb{Z}_5$
symmetry, which realizes one-
flavor dominance of the portal couplings consistently with the PMNS mixing
matrix. We also discuss possible
flavor leakage in a type-I seesaw completion and study experimental probes of the model through
lepton observables, especially
lepton flavor non-universality in $Z$
boson decays.
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Instrumentation and Methods for Astrophysics
First overnight balloon flight of the GRAINE 2023 emulsion gamma-ray telescope enabled by a large-scale pressure-vessel gondola
Hiroki Rokujo, Shigeki Aoki, Takashi Azuma et al. (+34 more)
The Gamma-Ray Astro Imager with
Nuclear Emulsion (GRAINE) project conducts precision observations of sub-GeV–GeV
cosmic gamma rays using a balloon-borne
nuclear-emulsion
telescope with high angular resolution. In GRAINE 2023, a 2.5-m$^{2}$
telescope was flown in the project's first overnight balloon flight, including observation periods for the Vela
pulsar and
Galactic center region. To operate the
telescope under the low-pressure and low-temperature stratospheric environment, the balloon-style pressure-vessel concept was scaled up to a lightweight gondola with an internal length of 4.9 m. A new aluminum-
alloy ring structure and a lightweight membranous-shell material, SHL-300MDL, were developed. While the
telescope aperture was increased by a factor of 6.6 over GRAINE 2018, the pressure-vessel gondola mass was limited to 179 kg. Ground tests of the completed flight assembly demonstrated a differential pressure above 100 hPa at room temperature and at a mean temperature of $-66.0^{\circ}$C. The payload was launched from Alice Springs, Australia, in April 2023 and achieved a total flight duration of approximately 27 h, including 24.3 h of level flight. Although the upper membranous shell reached approximately $-60^{\circ}$C at night, the vessel internal pressure remained above the required 100 hPa throughout level flight. These results demonstrate that the developed gondola can accommodate a 2.5-m$^{2}$ emulsion gamma-ray
telescope and maintain the required pressure during overnight stratospheric flight. Scientific analyses of astrophysical and atmospheric gamma rays, including dedicated analysis of the
Galactic center region, are ongoing using the recovered emulsion data. This development provides a technical basis for repeated observations with future large-area GRAINE
telescopes.
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All authors Hiroki Rokujo, Shigeki Aoki, Takashi Azuma, Hirotaka Hayashi, Yudai Isayama, Atsushi Iyono, Takumi Kato, Tsuyoshi Kawahara, Koichi Kodama, Ryosuke Komatani, Masahiro Komatsu, Masahiro Komiyama, Hideyuki Minami, Kunihiro Morishima, Fumiya Murakami, Shogo Nagahara, Naotaka Naganawa, Mitsuhiro Nakamura, Tomoaki Nakamura, Yuya Nakamura, Noboru Nakano, Toshiyuki Nakano, Kazuma Nakazawa, Miyuki Oda, Kazuhiro Okamoto, Osamu Sato, Kai Shimizu, Amon Suganami, Yuki Sugi, Kou Sugimura, Satoru Takahashi, Ikuya Usuda, Saya Yamamoto, Jun Yamashita, Mayu Yamashita, Shoma Yoneno, Masahiro Yoshimoto
Quantum Physics
Nalan Wang and Lin Chen
We investigate various properties of multipartite block-positive operators, decomposable EWs (DEWs), and non-decomposable EWs. We provide a necessary and sufficient condition to construct a special DEW using the multipartite GHZ state. For multipartite DEW, we explicitly characterize the supremum and infimum of maximum and minimum
eigenvalues, as well as the trace of its square. We also derive other results concerning NDEW,
eigenvalues of $2 \times n$ EWs and the corresponding physical implications. Furthermore, we investigate the tightness of inequalities of these
eigenvalues with examples.
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High Energy Physics (Phenomenology)
Towards power corrections in the factorization of baryon quasi-distribution amplitudes in LaMET
Yu-Ji Shi and Jun Zeng
Light-cone distribution amplitudes (LCDAs) are essential to precision phenomenological studies. They can be accessed from
lattice QCD through the large-momentum effective theory (LaMET) via quasi-distribution amplitudes (quasi-DAs). Factorization of quasi-DAs receive power corrections in inverse powers of the
hadron momentum, including target-mass and higher-twist corrections. In this work, we present the first systematic analysis of such power corrections for the leading-twist
baryon quasi-DA. Establishing the moment relation between the quasi-DA and the LCDA, we derive an exact closed-form relation that resums target-mass correction to all orders at leading twist. This result also applies to heavy
baryons and to quasi-transverse-momentum-dependent distributions. We numerically assess these corrections for the $\Lambda$
baryon quasi-DA using existing
lattice data, finding that the target-mass correction decreases rapidly with increasing
baryon momentum and is almost negligible in the endpoint regions. In addition, we explicitly construct the next-to-leading-twist operators entering the quasi-DA factorization. Our results are a first step toward quantifying the power corrections in future
lattice determinations of light or heavy
baryon LCDAs.
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Chemical Physics
Simulating spectrally resolved exciton–exciton-interaction pump–probe spectroscopy
Kateřina Charvátová, Matteo Bruschi and Pavel Malý
Exciton–
exciton-interaction pump–probe spectroscopy (EEI–PP) captures the fifth-order signal of light-matter interaction, directly probing
exciton–
exciton annihilation. This allows studying excitation energy transport even in extended, nearly isoenergetic landscapes. Although spectrally resolved fifth-order signals have already been explored in simplified cases, in larger systems only spectrally integrated signals have been analyzed. We present a microscopic theoretical description for spectrally resolved EEI–PP response with realistic lineshapes, revealing how single- and multi-
exciton state structure shape the spectral features and dynamics. The description is applicable to large molecular systems such as squaraine
polymers, facilitating a direct comparison with experimental spectra. By a decomposition of the total signal into individual excitation pathways, we demonstrate that the spectral resolution is needed to distinguish otherwise intertwined single- and multi-
exciton dynamics, such as single-
exciton relaxation and
exciton–
exciton annihilation.
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Fluid Dynamics
Physics-Guided Machine Learning for Predictive Turbulent Combustion Simulation
Shubhangi Bansude and Jay Patel
Predictive simulation of turbulent combustion remains challenging because stiff chemical kinetics, turbulent transport, molecular mixing, and heat release interact nonlinearly across unresolved scales. In the filtered or averaged formulations, reaction rate is unclosed, and the integration of detailed chemistry constitutes the dominant computational cost. Conventional closures such as mixing-limited models, flamelet and
manifold methods, conditional moment closure, and transported probability/filtered density function (PDF/FDF) formulations, encode substantial physical insight, but rely on structural assumptions that may lose validity outside their calibrated regimes. Machine learning offers a complementary approach because of its ability to approximate complex nonlinear functions. In turbulent combustion, this capability can be used to relax restrictive closure assumptions, learn unresolved nonlinear mappings from data, and accelerate expensive computations such as detailed chemistry computation. However, purely data-driven models may violate conservation laws and thermochemical consistency. They may also extrapolate poorly outside the training domain and destabilize the CFD solvers in which they are embedded. Physics-guided machine learning (PGML) addresses these failure modes by incorporating prior knowledge throughout the modeling pipeline: in the training data and input features, the model architecture, the loss function, the hybrid closure structure, and the solver-aware validation protocol. This article reviews PGML for
turbulence-chemistry interaction (TCI) modeling within this framework.
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Quantum Physics
Hardware-Efficient Exchange-Only QML: Singlet-Triplet Spin Chains via Inter-pair Coupling without Magnetic Gradients
Yuichiro Minato
Standard universal
quantum computing using exchange-only
qubits typically requires three physical
spins per logical
qubit, leading to significant hardware overhead. Conversely, two-
spin units offer higher density but rely on local
magnetic field gradients for control, increasing integration complexity. In this paper, we propose a resource-efficient
quantum machine learning (QML) architecture that achieves high expressibility using minimal two-
spin units and Heisenberg exchange interactions alone, without any
magnetic gradients. We shift the paradigm from universal gate-based control to utilizing the intrinsic, time-domain dynamics of a
spin chain as a learning resource. Numerical simulations on MNIST digit classification demonstrate that the
symmetry-protected constraints of isolated
spin pairs are bypassed by leveraging inter-pair exchange coupling. This interference-mediated state mixing significantly enhances the expressibility of the
Hilbert space. The model reaches a test-set accuracy of 90.9% +/- 0.2% over five independent seeds on the full 10,000-image MNIST test set. Under an identical linear readout, the trained
quantum feature map (88.1%) clearly outperforms a classical linear baseline on the same PCA inputs (83.2%) as well as an untrained (reservoir-style) version of the same dynamics (53.0%), demonstrating that the learned, input-dependent exchange pulses implement a genuinely non-linear and trainable feature map. The protocol is also robust to experimentally relevant imperfections: accuracy remains at 89.9% under 10% quasi-static pulse-area noise and at 89.8% when every observable is estimated from 10^3 measurement shots. These findings suggest that competitive QML can be executed on the simplest possible
semiconductor spin-chain hardware, bypassing the need for leakage-prone encodings or complex micro-magnet integration.
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