Mathematical Physics
Threshold spectral transition for a fermion-boson pair on the one-dimensional lattice
Sobir S.Ulashov and Shakhobiddin I.Khamidov
We study a two-particle
lattice Schrödinger operator describing a
fermion-
boson pair on the one-dimensional
lattice $\mathbb Z$ with zero-range on-site interaction of strength $\mu\in\mathbb R$ and mass ratio $\gamma>0$. Using relative coordinates and fiber decomposition with respect to the total quasi-momentum $k\in\mathbb T:=(-\pi,\pi]$, we obtain a real symmetric fiber
Hamiltonian $H_{\mu,\gamma}(k)$ in $\ell^2(\mathbb Z)$ with essential spectrum $$ [\,2(1+\gamma)-2a_\gamma(k),\,2(1+\gamma)+2a_\gamma(k)\,], \qquad a_\gamma(k)=\sqrt{1+2\gamma\cos k+\gamma^2}. $$ For $a_\gamma(k)>0$ and $\mu\ne0$, the operator has a unique simple discrete
eigenvalue $$ E_\gamma(k,\mu)=2(1+\gamma)+\operatorname{sgn}(\mu)\sqrt{\mu^2+4a_\gamma(k)^2}, $$ lying below the band for $\mu<0$ and above it for $\mu>0$, with an exponentially decaying eigenfunction. At the exceptional fiber $(\gamma,k)=(1,\pi)$, the band collapses to ${4}$ and the unique simple
eigenvalue is $E_1(\pi,\mu)=4+\mu$. At the critical coupling $\mu=0$ and $a_\gamma(k)>0$, both spectral edges are threshold resonances with bounded non-square-integrable solutions. As $\mu\to0^\pm$, the discrete
eigenvalue approaches the corresponding threshold with $$ |E_\gamma(k,\mu)-E_{\mathrm{thr}}^\pm(k)| =\frac{\mu^2}{4a_\gamma(k)}+O(\mu^4), $$ and the normalized eigenfunction converges to the resonant solution. For strong coupling, $E_\gamma(k,\mu)=\mu+2(1+\gamma)+O(|\mu|^{-1})$, while the eigenfunction localizes at the interaction site. We also classify the joint limit $\mu\to0^\pm$, $(\gamma,k)\to(1,\pi)$ according to the relative scale of $|\mu|$ and $a_\gamma(k)$, revealing the nonuniformity of the weak-coupling threshold asymptotics.
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Astrophysics of Galaxies
Energetics of AGN Feedback
Ross J. Turner, Andrew Sullivan and William R. Q. Gaffney
Integrating realistic active
galactic nucleus (AGN) feedback into cosmological hydrodynamical simulations remains a major challenge as resolving the spatial coupling of jet energy over
cosmic timescales is computationally prohibitive. We present an analytic framework that predicts the radial and polar-angle dependence of feedback energy from lobed AGNs, enabling a physically motivated, computationally efficient prescription for jet feedback. Built upon the
Radio AGN in Semi-analytic Environments (RAiSE) dynamical model, our approach tracks the post-AGN jet phase
evolution of
radio sources through two distinct mechanisms: buoyantly rising bubbles subject to ablation, and the gravitational collapse of swept-up gas in the shocked shell. We find that these two feedback mechanisms produce strongly contrasting spatial distributions across ten representative cluster environments. Buoyant bubbles preferentially deposit energy in steep density gradients near the core radius, while the collapsing shocked gas shell drives heating within flatter cluster cores. Weak, short-lived AGN outbursts ($Q<10^{37}$ W and $t_{\rm on}<10$ Myr) confine their energy deposition to the inner 10 kpc of the cluster; longer-lived events ($t_{\rm on} \geqslant 100$ Myr) deposit less than 1% of their injected energy within 30 kpc. We find that time-averaged heating rates across multiple outbursts are sufficient to offset radiative cooling in all but the highest density cluster cores (within 100 kpc) for duty cycles of $0.08< \delta \leqslant 1$. This framework provides a scalable basis for modelling anisotropic, physically motivated jet feedback that can be incorporated into next-generation cosmological simulations.
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General Relativity and Quantum Cosmology
Two-branch detector response for Dirac infall into a Schwarzschild–MOG black hole
Nikko John Leo S. Lobos and Emmanuel T. Rodulfo
We study a localized
spin-$1/2$ detector falling into a Schwarzschild–MOG black hole. The detector interacts with a neutral massless scalar field through a charge-preserving two-level transition, while its translational wave packet obeys the MOG-charged Dirac equation. Near the outer horizon, the separated radial system reduces to an inverse-square equation with index $\Theta_{\rm D}=E_{\rm H}/(2\hbar\kappa_\alpha)$. The gauge-invariant horizon energy satisfies $E_{\rm H}=m_\psi U_{\rm H}>0$ for every future-directed crossing trajectory. We quantize the scalar field in a globally normalized Boulware scattering basis and retain both radial-flux branches of a mode that is outgoing at infinity. This treatment does not identify a local outgoing ansatz with a complete mode. A finite radial gate $\chi_p(x)=(x/L_\chi)^p e^{-x/L_\chi}$ gives closed-form excitation and absorption probability densities that include the ingoing contribution and scattering-phase interference. Within the controlled near-horizon approximation, the full detailed-balance ratio factorizes into a branch-resolved outgoing ratio and a two-branch factor. Only the outgoing ratio approaches $\exp(-2\pi\nu/\kappa_\alpha)$ when the near-horizon, adiabatic, high-gap, and branch-isolation conditions all hold. The leading switching correction is controlled by $(\nu/\kappa_\alpha)/(S_\pm L_\chi)$, not by $(S_\pm L_\chi)^{-1}$ alone. In a weak-MOG expansion, the local correction separates into surface-
gravity, trajectory-prefactor, and finite-gate terms. The full response also contains a contribution from global scattering. This separation shows which terms follow from the local horizon geometry and which depend on the detector protocol and scalar propagation outside the horizon region.
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Quantum Physics
GNSS-free quantum gravity-aided navigation and fine-scale marine surveying with a strapdown quantum gravimeter
Patrick J. Everitt, Donald H. White, Todd Lyon et al. (+19 more)
Global
navigation satellite systems (GNSS) are often disrupted or unavailable at sea, and unaided inertial
navigation systems (INS) drift without correction.
Quantum-sensing-based
gravity map matching offers a passive, infrastructure-free aid, but field demonstrations of GNSS-free
quantum gravimetric
navigation have not been reported. Here we perform
gravity map matching and fine-resolution
gravity survey with a mobile
quantum gravimeter aboard a 29 m surface vessel. We hybridize an atomic sensor with a classical accelerometer for bias stabilization and independently mechanize a
navigation-grade IMU, all installed in an uncontrolled cabin with no environmental stabilization or calibration. Operated in both gimbaled and strapdown configurations over identical traversals, the hybrid sensor corrected the inertial solution over an 83 km maritime trajectory by referencing locally measured
gravity to a satellite-derived anomaly map.
Gravity-aiding constrains INS drift and delivers bounded positioning at nautical-mile-level accuracy, with GNSS excluded throughout the measurement chain. In a separate GNSS-referenced mode, the same system surveyed coastal routes up to Sea State 4, achieving mGal-level agreement with gravimetric maps and sub-mGal repeatability and stability, with gimbaled and strapdown operation performing comparably. Resolved anomalies reach an along-track scale of ~300 m, 50X finer than the satellite map's half-power wavelength. A 56 h stationary test shows atom referencing lowers long-term drift ~70X versus the classical channel alone. These results provide the first same-instrument comparison of gimbaled and strapdown mobile
quantum gravimetry and the first fully GNSS-independent
gravity-map-matching
navigation demonstration using a
quantum gravimeter, pointing toward compact, autonomous-platform-ready
quantum sensing for GNSS-denied maritime
navigation and survey.
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All authors Patrick J. Everitt, Donald H. White, Todd Lyon, Murat Muradoglu, Alessandro D'Ortenzio, Aaron J. Canciani, Malo Cadoret, Daniel D. Brown, David Adams, Yosri Ben-Aïcha, Suraj Bijjahalli, Mojtaba K. Farsani, Alexander Rischka, Karandeep S. Gill, Magdalena Meyer, Henry W. Orton, Nicholas P. Robins, Reuben Symon, Michael J. Biercuk, Michael R. Hush, Stuart S. Szigeti, Russell P. Anderson
Physics and Society
Giant strongly biconnected components of directed networks: a generating function approach
Minsoo Yang, Reinhard Laubenbacher and Byungjoon Min
Strongly connected components (SCCs) characterize modular structure in directed networks but are fragile to single node failures. We study strongly biconnected components (SBCs), which are the set of nodes in which every node pair remains mutually reachable after the removal of any single node, as a more robust notion of connectivity. Using a generating function formalism, we derive the size of the
giant SBC and analyze its percolation behavior under random node and link removal. We show that the
giant SBC emerges at the same threshold as the
giant SCC but grows more slowly due to stricter connectivity requirements. We also applied our theoretical framework to real-world biological networks including gene regulatory networks and neural connectome. Our framework provides insight into the interplay between connectivity, redundancy, and robustness in complex directed systems.
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Physics and Society
$(k,n)$-core percolation on hypergraphs with anchor nodes
Hoseung Jang, Byungjoon Min and Ginestra Bianconi
Hypergraphs describe higher-order interactions that involve more than a pair of nodes. A characteristic feature of hypergraphs is that their robustness can be strongly affected by the different roles of the nodes. Indeed, some nodes might be essential for a hyperedge's function, while others might not be. The loss of a single essential node completely destroys the hyperedge it belongs to, while the loss of a non-essential node has a buffering effect, inducing the hyperedge to simply reduce its size. In order to capture this phenomenology, we formulate a comprehensive theoretical framework for $(k,n)$-core percolation models on hypergraphs, where each node of a hyperedge is an anchor with probability $\theta$, and a hyperedge fails if an anchor node fails. Hypergraph $(k,n)$-core percolation problems can be classified as first-neighbor and second-neighbor problems, indicating that in the
pruning process the connectivity is ensured only by the state of the first neighbors or the second neighbors, respectively. We derive self-consistency equations for first-neighbor and second-neighbor (node- and hyperedge-based)
pruning processes, and obtain the size of the
giant $(k,n)$-core. We obtain the phase diagram, including continuous and discontinuous transitions, and confirm our theory on random hypergraphs using numerical simulations. The results show how the heterogeneity of the nodes' functional roles and the extended range of the interactions affect the robustness of higher-order networks.
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Solar and Stellar Astrophysics
Sequential Magnetic Reconnections in a Fishbone-like Structure Leading to Recurrent Brightenings
Bo Yang, Jiayan Yang, Junchao Hong et al. (+1 more)
The fine-scale release of
magnetic free energy in the
solar atmosphere is a fundamental open question in
solar physics. Multi-wavelength observations at high spatiotemporal resolution now offer a direct window into this process. Using data from NVST, SDO, IRIS, and Hinode, we reveal the energy release process in a fishbone-like
magnetic structure within active region 12297. The fishbone-like structure consists of a spine along a narrow, elongated positive-polarity field, with herringbone branches rooted in negative-polarity sunspots. Persistent photospheric
magnetic flux emergence and shearing motions are observed beneath the fishbone-like structure, which may play a key role in maintaining its
topology and producing the recurrent brightenings. During brightenings, compact bright features propagate sequentially from west to east along the spine, accompanied by bidirectional flows along the branches and
plasma blobs ejected toward the distant positive sunspot. These propagating features could be interpreted as signatures of sequential
magnetic reconnection events occurring in chronological order at nodes along the spine, predominantly in the chromosphere and transition region. Our observations may provide evidence that recurrent brightenings could arise from repeated sequential reconnection events organized by a coherent
magnetic structure, deepening our understanding of how such recurrent brightenings are generated and how
magnetic free energy is dissipated at fine scales in
solar active regions.
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All authors Bo Yang, Jiayan Yang, Junchao Hong, Yi Bi
High Energy Astrophysical Phenomena
Energy Partition in AGN-driven Bubbles of NGC 4438: From Nuclear Bubbles to a Galaxy-scale Outflow
Luan Luan, Jiang-Tao Li, Jianghui Xu et al. (+4 more)
Jets launched by accreting supermassive black holes represent a major mode of active
galactic nucleus (AGN) feedback. However, how their energy is divided among bulk kinetic motion, thermal gas,
magnetic fields,
cosmic rays (CRs), and radiation - and how this distribution changes with spatial scale - remains poorly constrained. NGC 4438 provides a unique laboratory for probing this
evolution, hosting two 200-pc-scale
nuclear bubbles and a lopsided ~10 kpc
galaxy-scale
outflow plausibly associated with the same AGN. We present a multi-wavelength analysis to investigate the morphology, radiation mechanisms, and energetics of these structures. Joint
radio-X-ray modeling shows that the non-thermal emission in the
nuclear bubbles may require two distinct populations of
cosmic-ray electrons, suggesting that in addition to shock acceleration at the bubble rim, the highest-energy particles may be linked to acceleration processes closer to the unresolved central engine. A spatially resolved energy inventory reveals that bulk kinetic energy dominates the current energy budget of the
nuclear bubbles, while roughly half of the injected energy has already been transformed into thermal, CR, and
magnetic energy, as well as radiative losses. Across all bubble sizes, the thermal and
magnetic pressures are consistent within the uncertainties, implying that
magnetic fields remain dynamically significant on all examined spatial scales. Furthermore, the empirical correlation between
radio luminosity and jet power, established for kiloparsec-scale jet bubbles (MerloniHeinz2007), matches the energetics of the
galaxy-scale
outflow but substantially overestimates the power of the 200-pc-scale
nuclear bubbles, underscoring the scale dependence of jet energy dissipation.
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All authors Luan Luan, Jiang-Tao Li, Jianghui Xu, Yang Yang, Guilin Liu, Fulai Guo, Q. Daniel Wang
Quantum Physics
Certified decoding of quantum LDPC codes
Ragavi Krishnamoorthy, Florian Gerhardt, Johannes Knaute et al. (+8 more)
Quantum low-density parity-check (qLDPC) codes reduce the
qubit overhead of fault-tolerant
quantum computation by an order of magnitude, but their decoding is harder than its classical counterpart: because many physical errors are equivalent up to stabilizers, the degenerate maximum-likelihood (ML) decoder must compare the probabilities of entire equivalence classes of errors, that is, partition functions, rather than single errors. The workhorse decoder BP+OSD sidesteps degeneracy heuristically and offers no guarantees. We treat degenerate decoding as probabilistic inference in an undirected graphical model: the probability of each logical class is the partition function of an unconstrained, strictly positive Markov random field over the code's check variables, a construction that generalizes the random-bond Ising mapping of the surface code to arbitrary CSS codes and to spacetime decoding with measurement errors and
circuit-level noise. On this model we build two decoders. The first estimates all class partition functions by annealed importance sampling with common random numbers and attaches to every decision a certificate of optimality: a paired bootstrap test, or, composed with constant-factor
estimators such as WISH, an exact optimality proof. The second is region-based: the Bethe free energy, whose bias cancels between classes, reproduces exact ML decoding on every tested surface-code instance at millisecond cost, and enlarging the regions to elimination clusters makes exact degenerate ML decoding of the [[72,12,6]] bivariate bicycle code feasible. Across surface codes and the bivariate bicycle codes [[72,12,6]] and [[144,12,12]], under code-capacity, phenomenological, and
circuit-level noise, the sampling decoder matches or exceeds BP+OSD while certifying the bulk of its decisions, and the certificate flags exactly the syndromes on which any fast decoder should be distrusted.
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All authors Ragavi Krishnamoorthy, Florian Gerhardt, Johannes Knaute, Thomas Klir, Stefan Raimund Maschek, Erik Schulze, Tomislav Maras, Alexander Dotterweich, Loong Kuan Lee, Christian Bauckhage, Nico Piatkowski
Atomic Physics
Robust watt-level continuous-wave deep-ultraviolet lasers near 230 nm
J. Cai, M. Stoepper, P. Agarwal et al. (+20 more)
Continuous-wave (CW) deep-ultraviolet (DUV)
lasers near 230~nm enable
laser cooling of AlF, Cd, and Zn, but second-harmonic generation below 237~nm relies in practice on beta-barium borate (BBO), whose walk-off and UV-induced degradation hinder sustained operation. We demonstrate compact, affordable VECSEL-based systems informed by four years of operating 14 DUV cavities in 12
laser systems across six European laboratories. External LBO cavities produce nearly 4~W at 463~nm with 94% cavity efficiency. We compare spherically and elliptically focused Brewster-cut BBO cavities with a normal-incidence AR-coated design. The AR-coated cavity delivers the highest power and efficiency, reaching 1.0~W at 51% cavity and 44% external efficiency; the spherical Brewster cavity reaches 700~mW and maintains constant circulating power over 70~h, while elliptical focusing reduces peak intensity sixfold and improves beam quality, albeit with greater
alignment sensitivity. Collaboration-designed DUV optics, AlF spectroscopy, and Cd trapping validate the system.
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All authors J. Cai, M. Stoepper, P. Agarwal, L. Palánki, C. Alarcón-Robledo, W. W. W. Liu, P. Kukreja, R. Ferstl, H. Foltas, L. Möller, D. J. Brown, C. J. H. Rich, M. Chiarotti, T. Uusitalo, R. Thomas, J. Domarkas, M. Guina, J.-P. Penttinen, S. Stellmer, N. Poli, S. C. Wright, S. Hannig, S. Truppe
Disordered Systems and Neural Networks
Defect states in three-dimensional diamond photonic band gap crystals
Julia Rocha, Bart A. van Tiggelen, Ad Lagendijk et al. (+2 more)
We perform a theoretical study of defect states within the photonic band gap of three-dimensional diamond
crystals composed of point scatterers and doped with substitutional defects. The defects introduce localized states inside the photonic band gap, whose existence conditions and eigenfrequencies are expressed in terms of the on-site Green's function of the ideal defect-free
crystal. Off-site Green's functions are also calculated as function of distance and are shown to vanish within approximately two unit
cells. Finite-size effects are analyzed by comparing the results obtained in the infinite-
crystal limit with numerical simulations based on the coupled-dipole method. The latter not only reproduce the eigenfrequencies of the defect states within the band gap, but also provide their lifetimes originating from the finite
crystal size. The lifetimes of the defect states increase exponentially with
crystal size, becoming very long for large
crystals. In addition to defect states in the three-dimensional photonic band gap, the defects also give rise to strongly detuned states outside the gap, which decouple from the spectrum of the ideal defect-free
crystal.
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All authors Julia Rocha, Bart A. van Tiggelen, Ad Lagendijk, Willem L. Vos, Sergey E. Skipetrov
High Energy Physics (Theory)
Pair creation in weak gravity and gauge backgrounds: spinning fields and binary stars
S. A. Franchino-Viñas, N. Varacalli and O. Zanusso
We study pair creation for
quantum fields of
spin $0$, $1/2$, and $1$ in the presence of weak gravitational and gauge backgrounds. Using resummed heat-kernel techniques, we obtain closed expressions for the pair creation probability up to quadratic order in the “generalized
curvatures”. In addition, for gravitational backgrounds, we recast the pair production probability in terms of the matter distribution required for consistency with the Einstein equation. Finally, to illustrate the powerfulness of our methods, we analyze the effect of pair creation in a binary
star system.
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Solar and Stellar Astrophysics
Triple-induced mergers of black hole binaries: A comprehensive look at the role of stellar evolution, dynamical stability, and spin evolution
C. W. Bruenech, S. Toonen, T. Boekholt et al. (+1 more)
Mergers of black holes (BHs) have been shown to be a ubiquitous phenomenon in the Universe. However, uncertainties remain in our theoretical understanding of the
evolution of the BHs prior to their merger. Black hole progenitors are seemingly born primarily in triples or higher-order multiples, and the presence of a tertiary object can perturb a black hole binary (BHB) enough to precipitate a merger. We used population synthesis coupled with orbit-averaged descriptions of triple dynamics to evolve a population of triples with initially wide orbits and massive progenitors. Wide orbits were chosen to avoid
stellar interaction prior to BH formation. Systems that remain bound and form an inner BHB were evolved using a direct n-body code with post-Newtonian terms up to an order of 2.5. We also simulated the precession of the BH
spin vectors by coupling the n-body solver with the differential equations for the
spins. For the dynamically stable triples with inner BHBs, mergers occur with an estimated rate density of $\sim 5$ Gpc$^{-3}$ yr$^{-1}$. Mergers also occur in triples that become dynamically unstable at a rate of $\sim 1.4$ Gpc$^{-3}$ yr$^{-1}$. At the point of entering the 10 Hz gravitational wave frequency band, the merging inner binaries exhibit eccentricities between $10^{-4}$ and $10^{-2}$. The final effective
spin of a BHB that merges through this channel can display a wide range of values between $-1$ and $1$, with a slight tendency towards $\chi_\text{eff} \approx 0$. This is a result of the strong three-body dynamics experienced by the merging triples before the inner binary begins to shrink due to GW emission. The inner angular momentum can explore the full phase space before the binary rapidly shrinks and decouples from the tertiary, effectively freezing out the effective
spin to its value at the time of the highest inner eccentricity.
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All authors C. W. Bruenech, S. Toonen, T. Boekholt, A. Dorozsmai
Quantum Physics
A universal loss-limited optimum for fixed multi-pass quantum sensing per absorbed photon
Christoph F. Wildfeuer
Multi-pass schemes send a
photon through a sample several times to learn more about it. When the sample rather than the light is scarce, the natural figure of merit is the information gained per
photon the object absorbs. We show that one constant fixes the loss-limited optimum of every fixed scheme in which a single
photon passes repeatedly through the sample and is detected once at the end. Three properties suffice: information that grows as the square of the pass number, a fixed survival probability per pass, and no dose from a
photon already lost. They force a single trade-off function $h(x)=x^2/(e^x-1)$, where $x$ is the number of passes times the loss per pass. Its maximum, 0.648, sits at $x_{\mathrm{opt}}=1.594$. The loss-limited ceiling of interaction-free interrogation and the multi-pass phase optimum of Yu et al. are two instances. Phase sensing of a weakly absorbing object is a third, optimal at $m_{\mathrm{opt}}=x_{\mathrm{opt}}/(\epsilon+\alpha)$ passes; the absorption $\alpha$ and the parasitic loss $\epsilon$ enter the optimum only through their sum, but the damage counts only $\alpha$. N00N states and their loss-robust generalisations do worse per absorbed
photon, and optimising over
photon number and pass number together returns a single recycled
photon. Two further problems are priced in the same measure. Absorption estimation gains nothing, for any scheme. Detecting a faint companion below the Rayleigh limit costs the companion a dose that does not depend on its faintness, while under direct imaging the dose grows without bound. For a fragile sample the gentlest measurement is also the simplest one: a single
photon, recycled.
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Plasma Physics
Ion-acoustic eigenmodes in a helical magnetic mirror
Ivan Chernoshtanov
Plasma rotation together with corrugation of
magnetic field can result in coupling acoustic waves with different azimuthal wavenumbers and formation of eigenmodes with discrete frequency spectrum and zero longitudinal group velocity in a helical
magnetic mirror. Such eigenmodes can be destabilized by
plasma rotation as well as resonant interaction with trapped ions. Equations describing these waves in the linear approximation are derived and results of numerical solving the equations are discussed. Probably these eigenmodes may drive anomalous ions scattering which is needed for effective suppressing flow of rarefied
plasma through a helical mirror.
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Materials Science
Direct current thermo-mechanical testing: Principles, uncertainty hierarchy, and its role in advanced materials characterisation
Abdalrhaman Koko, Sodiq Abiodun Kareem, Olajesu Favor Olanrewaju et al. (+4 more)
Direct current thermo-mechanical testing (DC-TMT), based on resistive Joule heating, enables rapid heating and cooling, steep thermal gradients and simultaneous mechanical loading, making it a powerful tool for probing deformation, phase transformations, oxidation-assisted damage and creep under conditions inaccessible to conventional furnace-based methods. Despite its growing use, DC-TMT lacks formal standardisation and is often misinterpreted as equivalent to bulk isothermal testing, overlooking intrinsic differences in thermal and mechanical fields. This review addresses that gap by consolidating four decades of research on specimen geometry, temperature measurement, strain characterisation and environmental control, and by classifying uncertainty sources as dominant, secondary and conditional. Evidence from modelling and experiment shows that temperature gradients, heating rate and gauge representativeness govern the reliability of inferred material behaviour. Applications across aluminium, steels, nickel-based superalloys, titanium
alloys, hardmetals, zirconium
alloys, shape
memory alloys and additively manufactured systems are critically assessed. The review highlights domains where DC-TMT provides reproducible mechanistic insight and conditions where direct equivalence with bulk data is not warranted. Implications include the need for transparent reporting, multi-sensor temperature validation and integration with electro-thermal modelling to enable rigorous, mechanism-focused interpretation.
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All authors Abdalrhaman Koko, Sodiq Abiodun Kareem, Olajesu Favor Olanrewaju, Rachael Williams, Justus Uchenna Anaele, Yuanbo T. Tang, Bryan Roebuck
Fluid Dynamics
An SPH–mesh Coupling for Vesicle Dynamics in Shear Flow
Kuiliang Wang, Xinwei Cai, Ting Ye et al. (+2 more)
We present a novel computational framework that couples smoothed particle hydrodynamics~(SPH) with a triangulated membrane mesh to simulate the dynamics of vesicles suspended in fluids. A novel interface-tracking approach enforces membrane impermeability naturally, without resorting to non-physical constraints such as particle reflection or bounce-back boundary conditions. The membrane model incorporates four distinct bending energy formulations, namely the minimal model, the spontaneous
curvature (SC) model, the
bilayer couple (BC) model, and the area difference elasticity (ADE) model, providing a versatile tool for diverse biophysical scenarios. The framework is rigorously validated against
equilibrium shapes and tank-treading motion of a vesicle, demonstrating excellent agreement with previous theoretical and numerical studies. A systematic investigation into the effects of each bending model on the vesicle's inclination angle, revolution frequency, and morphology in shear flow reveals key physical insights. Notably, spontaneous
curvature has a negligible effect on steady-state orientation but profoundly alters rotational dynamics at low reduced volumes through the emergence of dumbbell-like shapes with deep constrictions. In contrast, the BC and ADE models induce characteristic asymmetric and stomatocyte morphologies. Our results establish the proposed SPH–mesh coupling as an accurate and robust tool for exploring the complex, shape-dependent dynamics of vesicles in fluid flows.
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All authors Kuiliang Wang, Xinwei Cai, Ting Ye, Xuejin Li, Xin Bian
Solar and Stellar Astrophysics
BV photometry of the cataclysmic variable LY UMa
L. Dankova, D. Marchev, S. Peneva et al. (+1 more)
We performed B- and V-band photometry of the probable
dwarf nova LY UMa. We find that it has apparent magnitude V=15.26+/-0.03 on 2024-04-14, V=15.43+/-0.02 on 2025-04-28, and V = 15.57+/-0.02 on 2025-06-02. Using the
GAIA distance d=310pc, we find that the lower values correspond to absolute V band magnitude M_V=7.94-8.10 and indicate that the mass donor of LY UMa is a K7-K8V
star with M_V=8.0-8.5. Our B-band measurements show slightly bluer B-V index of LY UMa than that of its donor, consistent with its nature as a cataclysmic variable. Close to LY UMa is the Active
Galaxy Nucleus Mrk 153, for which we estimate V=14.81+/-0.03.
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All authors L. Dankova, D. Marchev, S. Peneva, R. Zamanov
Quantum Physics
Superextensive learning in quantum reservoirs at the onset of information scrambling
Jonas Freiheit and Francesco Campaioli
The idea that information processing is optimised near the boundary between order and chaos has emerged as a recurring principle across neuroscience, complex systems, and machine learning. Here we test this hypothesis in
quantum many-body systems, numerically simulating two-dimensional Ising networks of up to $N=20$
spins, operated as
quantum reservoirs for time-series
forecasting. Using out-of-time-order correlators (OTOCs), we locate the onset of information scrambling as the input strength is swept, separating regimes where information is frozen and scrambled across the whole reservoir state. We show that prediction precision peaks at the onset of scrambling, along with the number of computational-basis states that the reservoir actively populates. We then show that prediction precision grows as a power law $\sim N^{\alpha}$ in the reservoir size, superextensively $(\alpha>1)$ at the onset of scrambling and only sublinearly $(\alpha<1)$ in either neighbouring regime. Finally, we show that scrambling enhances the nonlinear components of the reservoir
memory while reducing its linear capacity. At the onset, the total
memory capacity grows superextensively, provided that the necessary “forgetting” mechanism is supplied by a collective relaxation channel. These results consolidate the role of information scrambling in learning systems, turning it from an operating point into a scaling law for the performance of
quantum reservoirs.
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High Energy Physics (Phenomenology)
Rare Exclusive Top Decays t , b M and Vector-Meson Helicity
M.Ahmadi, M.Monemzadeh and N. Tazimi
We present a leading-order study of the rare exclusive decays $t \to bM$, where $M$ denotes a pseudoscalar or vector
meson. Starting from the tree-level transition $t \to bW^* \to b(q\bar q')$ and using a factorization approximation, we derive compact expressions for the amplitudes and partial widths in which the long-distance QCD dynamics is encoded in the
meson decay constants $f_M$. We provide numerical branching-ratio predictions for representative modes such as $t \to b\pi^+$, $t \to bK^+$, $t \to bD_s^{(*)}$, and $t \to bB_c^{(*)}$, finding $\mathrm{Br} \sim 10^{-8}$–$10^{-7}$. For vector final states, we derive helicity amplitudes and Standard-Model polarization fractions, and we outline the sensitivity of these observables to anomalous
chiral $tWb$ couplings in the limit $m_b \to 0$. Our results provide an updated Standard Model (SM) baseline for rare exclusive top-
quark decays and a starting point for EFT interpretations of non-standard charged-current interactions.
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High Energy Astrophysical Phenomena
A Population Study for Searching Supermassive Binary Black Holes in Active Galactic Nuclei: Continuum Spectral Features and Periodic Variabilities
Zekun Li, Changshuo Yan and Youjun Lu
Active sub-pc supermassive binary black holes (SMBBHs) are expected to exhibit various electromagnetic signatures due to unique dynamical and
geometric structures of their
accretion, but observational identification of them remains challenging. In this paper, we adopt semianalytic models to investigate both deficits in spectral-energy-distributions (SEDs) of these systems induced by gaps/holes in their
accretion disks and periodic variations in their light curves induced by either orbital-modulated Doppler boosting or
accretion rate variation of each SMBH component. We construct a population model to generate SMBBHs across
cosmic time by considering their orbital
evolution and associated
accretion and radiation processes. By estimating the continuum emission from each mock system and its variation, we investigate the detection of SMBBHs via either SED-deficit signature or light curve periodicity under reasonably given criteria. We find that all-sky surveys with filters similar to those of the China Space Station
Telescope or Rubin/LSST could identify up to approximately $3\times 10^2$ SMBBHs via SED-deficit features and/or $10^3$ SMBBHs via periodicity ($\lesssim5$\,yr), although both selections may suffer from a high rate of false positives. A few to a dozen SED-deficit SMBBHs may be detected by future
pulsar timing arrays with signal-to-noise ratio $\gtrsim3$, enabling multi-messenger observations. Only $\sim20\%-53\%$ of SED-deficit selected SMBBHs may also be detected via periodic variations, and $\sim7\%-9\%$ of periodic variation selected SMBBHs may be detected via SED-deficit signatures. The false positives for those SMBBHs selected jointly by both methods are negligible, highlighting the importance of searching for active SMBBH systems using joint methods.
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Mathematical Physics
Free-Energy Asymptotics of the Two-Dimensional Quantum Heisenberg Ferromagnet
Andreas Klippel
We prove the leading low-temperature free-energy asymptotics of the nearest-neighbour
quantum Heisenberg ferromagnet on $\mathbb Z^2$. For every fixed $S\in\{\frac12,1,\frac32,\ldots\}$, the free energy per site satisfies \[ \lim_{\beta\to\infty}\beta^2S f_2(\beta,S)=-\frac{\pi}{24}. \] This formula was predicted by Takahashi's modified
spin-wave theory [15]. Napiórkowski and Seiringer proved the corresponding upper bound but left the matching lower bound in two dimensions open [13], a gap later highlighted again by Seiringer [14]. We prove this missing bound through a new comparison between the
magnon exclusion dynamics and free
bosons, based on extending wave functions to collision configurations with controlled kinetic cost.
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High Energy Physics (Phenomenology)
Pair production of $h$ in the $U(1)_X$SSM
Yue-Tong Liu, Shu-Min Zhao, Meng-Zi Cao et al. (+3 more)
Higgs pair production provides an important probe of the
Higgs self-interaction and the
Higgs potential structure. We study the lightest neutral
Higgs pair production process $gg \to hh$ via
gluon fusion at the 14 TeV LHC, in the $U(1)_X$ supersymmetric standard model. As a $U(1)$ extension of the minimal supersymmetric standard model (MSSM), this model introduces new superfields that bring additional one-loop contributions to the production amplitude. We analyze the parameter dependence of the cross section numerically and present contour distributions in two-dimensional parameter planes. The results indicate that the gauge couplings $g_X$ and $g_{YX}$ are the most sensitive parameters, and the model yields sizable new physics corrections under current experimental constraints. This work helps to understand
Higgs physics in the $U(1)_X$SSM and guides new physics searches at the high-luminosity LHC.
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All authors Yue-Tong Liu, Shu-Min Zhao, Meng-Zi Cao, Shuang Di, Rong-Zhi Sun, Xing-Xing Dong
Quantum Physics
High-Fidelity Entangled States in a Connectivity-Four Fluxonium Quantum Processor
J. Schirk, N. Bruckmoser, S. M. Taubenberger et al. (+10 more)
A central challenge in fluxonium-based
quantum processors is the extension of the
qubit connectivity to two-dimensional
lattices compatible with
quantum code-error correction. Here, we present a fluxonium
quantum processor that employs lumped-element resonator couplers which realizes, for the first time, a connectivity-four unit
cell with suppressed parasitic interactions. We achieve parallel single-
qubit gate fidelities exceeding 99.9 % in simultaneous randomized benchmarking experiments, while maintaining residual static ZZ interactions below 1 kHz across all coupled
qubit pairs. We implement resonator-induced phase (RIP) gates and
benchmark two-
qubit gate fidelities exceeding 99 % using interleaved randomized benchmarking. To cancel spectator errors observed in two-
qubit operations, we implement a refocused RIP gate, recovering coherent control in the presence of multi-
qubit connectivity. Furthermore, we prepare Greenberger-Horne-Zeilinger states of up to five
qubits with a tomographic fidelity of 90 %, verifying multi-
qubit entanglement within the unit
cell. These results establish the fluxonium-resonator-fluxonium architecture as a viable approach to realizing densely connected fluxonium processors and provide a scalable path toward
quantum error-correction-compatible processor architectures.
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All authors J. Schirk, N. Bruckmoser, S. M. Taubenberger, F. Wallner, N. J. Glaser, M. Zetzl, L. Huang, I. Tsitsilin, M. Werninghaus, L. Södergren, K. Liegener, C. M. F. Schneider, Stefan Filipp
High Energy Physics (Phenomenology)
Next-to-leading power endpoint DIS and PDF factorization
M. Beneke, M. Schnubel and R. Szafron
We study deep-inelastic scattering (DIS) in the threshold region $x\to 1$ beyond leading power in $1-x$ at leading twist. In the framework of position-space soft-collinear effective theory, we derive a factorization
theorem for the off-diagonal parton-scattering channel, which starts at next-to-leading power (NLP). The hadronic tensor separates into an anti-hardcollinear contribution from power-suppressed currents and a soft-collinear contribution from subleading Lagrangian interactions, whose convolution integrals exhibit endpoint divergences. We show that these divergences are resolved by endpoint factorization relations, implying that the parton distribution function (PDF) near threshold becomes a two-scale object at NLP. We derive the factorization of the NLP
gluon distribution at large $x$ in terms of hardcollinear matching coefficients and a subtracted soft-collinear function. We resum the leading logarithms of $1-x$ both from $d$-dimensional factorization in the $\overline{\rm MS}$ scheme and in an endpoint scheme based on refactorization, and establish the all-order relation between the two definitions of the PDF.
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High Energy Physics (Phenomenology)
Particle production in $p$-O collisions at LHC energy
Chuan Li and Georg Wolschin
We compare our previous predictions for charged-
hadron production in p-O collisions at an energy of sqrt(s_NN)=9.618 TeV as published in 2025 with preliminary Run 3 data from ALICE and adapt the model parameters to the data. Our three-source model comprises a
gluon-
gluon central source and two valence-
quark soft-
gluon fragmentation sources. We describe the initial conditions using color-glass-condensate states and calculate the time-dependent partial thermalization with a relativistic
diffusion model. An inversion of the maximum production amplitude at larger pseudorapidities from backward to forward towards peripheral collisions is predicted.
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Optics
Generalizing Thermal Transport in High-Contrast Metamaterials through Interfacial Fresnel Reflection
Seung Hyeon Ham, Yu Min Kim, In Hyeok Choi et al. (+1 more)
The rapid growth of generative AI has intensified the need for efficient heat dissipation in large-scale data centers. To control heat flow, thermal metamaterials with layered structures have been widely used, which impart the anisotropic properties of thermal conductivities. However, the conventional effective medium approximation (EMA) often fails to provide accurate predictions in systems with a high thermal conductivity contrast between adjacent layers embedded in a background medium. Here, we generalize the EMA by introducing two corrective coefficients that extend its validity to regimes where the conventional EMA was previously inapplicable, i.e., high-contrast thermal metamaterials with the background medium. Notably, one of these coefficients that we proposed has the same mathematical form as the Fresnel reflection coefficient in optics. This allows us to interpret the "reflection-like" behavior of heat flow as it penetrates adjacent layers with high thermal contrast. Our findings suggest that heat
diffusion, traditionally viewed as a purely dissipative process, can be understood intuitively through the framework of ray optics.
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All authors Seung Hyeon Ham, Yu Min Kim, In Hyeok Choi, Jeong Woo Han
High Energy Astrophysical Phenomena
Energy-dependent extension of the Crab Nebula as a diagnostic of ultrahigh-energy hadronic emission
Fang-Wu Lu, Bo-Tao Zhu, Ji-Yang Ren et al. (+1 more)
The energy-dependent apparent extension of the Crab Nebula, inconsistent with leptonic expectations between X-ray and TeV bands, can be naturally accounted for in a spatially resolved lepto-hadronic scenario. A transition to hadronic dominance occurs above $\sim400~\rm{TeV}$, with nearly pure hadronic emission at PeV energies. The predicted $68\%$ containment radius at $1.1~\rm{PeV}$ is $\sim1.4'$, about six times larger than in purely leptonic scenarios. This energy-dependent extension therefore provides an observable discriminator of the origin of ultra-high-energy gamma-ray emission in
pulsar wind nebulae, offering a diagnostic of PeV hadronic acceleration in the Crab Nebula.
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All authors Fang-Wu Lu, Bo-Tao Zhu, Ji-Yang Ren, Li Zhang
Chemical Physics
Battery Recycling: Mechanistic Modelling of LiCoO$_2$ Leaching with Coupled Diffusion-Reaction Kinetics and Film Passivation
Uddipta Sarma and Ganesh Madabattula
We developed a new mechanistic model for lithium and cobalt recovery during acidic-reductive leaching from LiCoO$_2$. The system considers HCl as an acid and H$_2$O$_2$ as a reducing
agent. The model tracks conversion of LCO, the particle radius, the acid, H$_2$O$_2$, formation-dissolution dynamics of Co$_3$O$_4$ film, the film thickness, recovery of lithium and cobalt, and moles of O$_2$. We introduced the film passivation effects for reduced recovery in the absence of H$_2$O$_2$. We validated the model against the experimental data of recovered Li and Co reported in literature at three acid concentrations (0.5 M, 1.5 M, and 2.5 M) and four H$_2$O$_2$ concentrations (0%, 0.2%, 0.4%, and 0.6% (v/v)). The model works reasonably well at 0.5 M and 1.5 M HCl for the 0% and 0.6% concentrations of H$_2$O$_2$. At 2.5 M HCl, the model over-predicts the data in the presence of H$_2$O$_2$, while it works well at 0% H$_2$O$_2$. We suggest pathways for further improvements in the model. The comprehensive mechanistic modelling framework for the leaching with a full list of the equations, the parameters, and the variables, reported for the first time, can be extended to other cathode chemistries and acid-reductive leaching systems.
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Quantum Physics
Low-leakage superconducting-qubit measurement with sub-100-ns total duration
Peter A. Spring, Adrian L. Hesse, Shiyu Wang et al. (+2 more)
Fast, accurate, and low-leakage
qubit measurement is a key requirement for
quantum error correction. Here, we demonstrate measurement of a superconducting transmon
qubit with a total duration of 97(1) ns, defined as the time from the start of the measurement pulse until the measurement-induced error on a subsequent $\pi$-pulse operation falls below $10^{-4}$. By combining a large state-averaged resonator decay rate of $\kappa_\mathrm{eff}/2\pi$ = 30.8 MHz with a dispersive shift close to the optimal SNR-per-
photon condition, we achieve an assignment error of 0.17(1)% using a 58-ns measurement pulse, with residual readout
photons depleting passively in tens of nanoseconds without an active depletion pulse. Using a repeated-measurement sequence together with a leakage-sensitive measurement, we
benchmark the measurement-induced state transitions, finding a per-measurement leakage rate of $2.7(2) \times 10^{-5}$, only twice the background rate and two orders of magnitude below the measurement-induced relaxation rate, which dominates the assignment error. Floquet simulations indicate that the multiphoton resonances present at the operating point are weakly coupled and traversed diabatically, without causing leakage. These results demonstrate that a large resonator decay rate, combined with a dispersive shift close to the optimal SNR-per-
photon condition, can enable fast, high-fidelity, low-leakage dispersive readout at small
qubit-resonator detuning.
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All authors Peter A. Spring, Adrian L. Hesse, Shiyu Wang, Shuhei Tamate, Yasunobu Nakamura