Plasma Physics
Study of low-frequency core-edge coupling in a tokamak: III. Core-localized MHD continuum pulsations & distant forced reconnection
Andreas Bierwage, Panith Adulsiriswad, Gyungjin Choi et al. (+2 more)
Slow magnetoacoustic pulsations (SMAPs) are found in MHD simulations of a tokamak
plasma whose safety factor $q$ near the center is flat and slightly above unity ($q \gtrsim 1$). SMAPs are located on the central plateau of the slow magnetoacoustic continuum $\omega_{\rm S} = k_\parallel c_{\rm S}$, where $c_{\rm S}$ is the speed of sound and $k_\parallel$ the wavenumber parallel to the
magnetic field. In our model, SMAPs exist when the ion viscosity and thermal diffusivity are sufficiently low. They can be driven unstable by a pressure gradient in the $q \sim 1$ region when the electric resistivity is sufficiently high. Exponentially growing SMAPs consist of standing slow waves on
magnetic surfaces that are radially synchronized into a quasi-interchange structure with poloidal/toroidal mode numbers $m/n=1/1$. After free energy depletion, saturated quasi-linear pulsations (alternating $n=1$ and $0$) in the central $q\sim 1$ region couple to distant $q\geq 2$ rational surfaces that undergo "reversible"
magnetic reconnection: as the
magnetic islands wax and wane with period $2\pi/\omega_{\rm S}$, their X- and O-points alternate. These results show how the MHD model facilitates non-local coupling of slow waves, pressure-driven resistive interchange and tearing. This motivates further study in kinetic models, where collisionless mechanisms for fast reversible reconnection exist and proper treatment of parallel dynamics will allow to assess the role of Landau damping as well as the question whether the ${\mathbf B}$ field's weak ergodicity in the $q\sim 1$ region allows the waves to outpace the ion's parallel streaming to maintain the thermal misbalance underlying SMAPs. Also of interest are pulsations closer to the Alfvénic branch, satisfying $\omega \approx k_\parallel v_{\rm A}$ with Alfvén speed $v_{\rm A}$, which require no resistivity and are less dependent on thermal misbalance.
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All authors Andreas Bierwage, Panith Adulsiriswad, Gyungjin Choi, Young-chul Ghim, Masatoshi Yagi
High Energy Physics (Phenomenology)
Generalised Dynamic Radius Jets for Robust Collider Analyses
Songshaptak De, Tousik Samui and Ritesh K. Singh
Jets and their reconstructions play a central role in precision measurements and searches for new physics at
hadron colliders. Conventional jet clustering
algorithms employ a fixed radius parameter, which may not optimally describe events containing jets of varying characteristic sizes. Building on the recently proposed dynamic radius jet clustering framework, we construct several substructure-inspired dynamic radius prescriptions based on jet angularities and energy correlation functions. A detailed study of these
algorithms is performed, including detector effects within the Delphes framework and in the presence of high pileup corresponding to an average of 150 interactions per event, with pileup contamination mitigated using the PUPPI
algorithm. The performance of the proposed
algorithms is compared with that of the standard anti-$k_t$
algorithm in boosted $Vj$ ($V=W^\pm,Z$) and $tj$ events against dijet backgrounds. Using jet substructure observables and multivariate analysis based on boosted decision trees, we find that the dynamic radius
algorithms lead to improved reconstruction of boosted heavy-particle jets and achieve better signal-background discrimination compared to the conventional fixed radius anti-$k_t$ clustering.
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Instrumentation and Methods for Astrophysics
Simultaneous PSF Matching via Dual Kernel Optimization
Carter Lee Rhea, Pieter Van Dokkum, Roberto Abraham et al. (+6 more)
Standard point spread function (PSF) matching
algorithms consider one image as the reference and aim to find a convolution kernel such that, when applied to the reference image, the PSFs of the reference and non-reference images are matched. This method works well if one image is a degraded version of the other. However, this is not always the case: if the PSFs of the two images have different orientations or shapes, a simple convolution of one of the images does not lead to a satisfactory match. While this can be trivially solved by convolving the first PSF with the second and vice-versa, this results in unnecessarily large PSFs. In this paper, we present a new
algorithm, Dual Kernel Optimization (DKO), that simultaneously solves for two convolution kernels, one for each image, such that the PSFs match and the sizes of the kernels are minimized. This results in a minimally-degraded final set of PSFs. Since this problem is highly degenerate, we use
Stochastic Gradient Langevin Dynamics (SGLD) which rigorously explores the parameter space and converges on the globally-optimal solution.We discuss the algorithmic challenges for this problem and the modifications to standard SGLD used to constrain it. Finally, we include a discussion on the application of this methodology to real-world images, including cases where the PSF varies over the field of view.
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All authors Carter Lee Rhea, Pieter Van Dokkum, Roberto Abraham, Imad Pasha, Steven R. Janssens, William P. Bowman, Deborah Lokhorst, Seery Chen, Qing Lui
High Energy Physics (Theory)
The cosmological necklace problem
Andreas Blommaert, Jonah Kudler-Flam, Vladimir Narovlansky et al. (+1 more)
We investigate 3d de Sitter
axion wormhole which contribute to the no-boundary density
matrix. We identify "cosmological necklace" solutions: an infinite series of Euclidean saddles corresponding with repeated bounces. This results in an unbound gravitational
entropy, and a divergent path integral. To remedy this, we study the gravitational path integral using a (mostly) Lorentzian lapse contour. Within a minisuperspace steepest-descent analysis, we find that a single necklace dominates, leading to a finite
entropy. A crucial element is to take into account an $(a\to -a)$ redundancy in the FLRW path integral, where $a$ is the scale factor. Surprisingly, the dominant solution is not purely Euclidean. Its
entropy turns out to be independent of the
axion flux, and equals the empty de Sitter
entropy. We also study higher-dimensional necklaces, sourced by either an
axion flux or by Yang-Mills instantons, and argue for qualitatively similar results: the single necklace solution dominates along a Lorentzian lapse contour.
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All authors Andreas Blommaert, Jonah Kudler-Flam, Vladimir Narovlansky, Erez Y. Urbach
Quantum Physics
Avoided crossings in spin-boson systems: consequences for adiabatic state preparation
Joona Marjamäki, Robert van Leeuwen and Riku Tuovinen
Avoided crossings in the correlated many-body spectrum play a central role in determining the conditions for adiabatic state preparation in interacting
quantum systems. We investigate this connection in finite
spin-
boson systems by combining exact diagonalization of the many-body spectrum with time-dependent simulations of adiabatic switching protocols. By comparing the adiabatically prepared state with the exact ground state, we determine the switching times required for reliable preparation as a function of the
spin-
boson coupling strength and bosonic mode structure. We show that regions of small many-body level spacings, associated with avoided crossings, impose the strongest constraints on adiabatic preparation and explain the observed dependence of the required switching times on the interaction strength. Furthermore, while the ground-state energy follows the overall spectral trends, local observables such as Pauli
matrix expectation values exhibit additional non-monotonic behavior arising from coherent oscillations in finite systems. These findings can provide concrete
benchmarks for both the theoretical treatment of open
quantum systems and practical implementations in
quantum simulation and
qubit control.
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Mesoscale and Nanoscale Physics
Spin-Polarized Magnetic Metal Electrodes for Magnetic Tunnel Junctions
Zhiyuan Duan, Peixin Qin, Li Liu et al. (+7 more)
Magnetic tunnel junctions are foundational components of spintronic
memory, sensing, and computing, and their performance depends critically on the
magnetic metallic electrodes. This Perspective examines electrode materials through the lens of
magnetic order and the distinct microscopic mechanisms that generate
spin-selective tunneling. Conventional ferromagnets, including CoFeB and half-metallic Heusler
alloys, support exchange-split electronic states and
symmetry-filtered tunneling, whereas compensated collinear and noncollinear antiferromagnets exploit sublattice selectivity,
spin-orbit anisotropy, vector
spin textures, and
magnetic multipoles. Altermagnets provide a collinear, zero-net-moment route based on
symmetry-allowed momentum-dependent
spin splitting. Across these material classes, we compare the origins of tunneling polarization, the roles of barrier evanescent states and interface termination, and strategies for electrically writing and reading the relevant
magnetic order. This comparison reveals a broader design principle: effective electrode polarization is not a scalar bulk quantity, but a momentum-, orbital-,
symmetry-, and interface-resolved transport property. Beyond the pursuit of ever larger tunneling magnetoresistance, future progress will depend on converting the unconventional
spin polarization of emerging
magnetic metals into electrically addressable, thermally robust, and reproducible tunneling functionality at realistic interfaces.
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All authors Zhiyuan Duan, Peixin Qin, Li Liu, Guojian Zhao, Sixu Jiang, Xiaoyang Tan, Jingyu Li, Xiaoning Wang, Ziang Meng, Zhiqi Liu
Quantum Physics · Cross-listed from cs.DC
A Block Decomposed QUBO Workflow for Chromosome-Y Phylogeny Reconstruction
Giuliana Siddi Moreau, Riccardo Berutti, Manuela Profir et al. (+3 more)
This paper sets out a computational workflow that reconstructs the phylogeny of human Y-chromosome populations from a Variant Call Format (VCF) file of biallelic Single Nucleotide Polymorphisms (SNP). The two classical phylogenetic decisions -
topology selection and root placement - are cast as Quadratic Unconstrained Binary Optimisation (QUBO) problems. The workflow combines two QUBO formulations with an Alternating Direction Method of Multipliers (ADMM) decomposition strategy and a plug-in Digitized Counter-Diabatic
Quantum Optimization (DCQO) solver, enabling large phylogenetic optimization problems to be executed across multiple classical or
quantum computing resources. The DCQO gate-based optimizer drives each ADMM-block QUBO with short-depth counter-diabatic
circuits in the impulse regime, without the necessity for an outer variational loop. The combination of ADMM decomposition and the DCQO block solver facilitates problem sizes that surpass the
qubit budget of any individual digital
quantum processing unit call, while maintaining the integrity of the original objective. The workflow extracts genotype information from VCF files, reconstructs
topology and rooting through two QUBO formulations, and annotates the resulting tree using PhyloTree. The resultant data set comprises a Nexus-annotated rooted tree, in addition to diagnostic figures. The workflow demonstrates the potential of modest-scale QUBO formulations combined with ADMM decomposition to serve as a scalable alternative to greedy heuristics in the domain of population genomics.
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All authors Giuliana Siddi Moreau, Riccardo Berutti, Manuela Profir, Lorenzo Pisani, Maria Laura Clemente, Lidia Leoni
Astrophysics of Galaxies
Discovery of an isolated RELHIC Candidate: J1351+0039
Jin-Long Xu, Alejandro Benitez-Llambay, Ming Zhu et al. (+6 more)
We report the discovery of J1351+0039, a new isolated dark
galaxy candidate identified through a blind HI survey with the Five-hundred-meter Aperture Spherical
radio Telescope (FAST), combined with deep optical imaging from the DESI Legacy Survey. The object displays a compact HI structure with a systemic velocity of V_{LSR} = 429.0 \kms and an inferred HI mass of 4.5*10^5 Msun at a distance of 3.6 Mpc. No optical counterpart is detected in the DESI images, with a g-band surface brightness limit of 28.1 mag arcsec^{-2}, corresponding to a
stellar mass limit of M_{
star} of 1.2*10^{5} Msun. The dynamical mass is estimated to be M_{dyn} of 1.3*10^{8} Msun, yielding a dark-to-baryonic mass ratio of 200, implying that J1351+0039 is overwhelmingly dominated by dark matter. While weak rotation is detected in J1351+0039, the kinematics are dominated by internal velocity dispersion, confirming pressure support and reminiscent of Reionization-Limited HI Clouds (RELHICs). J1351+0039 stands out as one of the most promising isolated RELHIC candidates, offering a unique laboratory for studying baryonic physics and dark matter in the absence of
star formation.
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All authors Jin-Long Xu, Alejandro Benitez-Llambay, Ming Zhu, Chuan-Peng Zhang, Nai-Ping Yu, Xiao-Lan Liu, Mei Ai, Ruilei Zhou, Bin Liu
Plasma Physics
Quasi-symmetric error field correction and applications to ITER
Gwang-Geun Seo, Jong-Kyu Park, S. J. Han et al. (+1 more)
Reliable correction of nonaxisymmetric error fields (EFs) is essential to the safety and performance of tokamak operation. Although resonant error field correction (EFC) is well established, supported by an improved understanding of 3D
plasma response, the residual fields left after resonant EFC remain an open question: they are expected to be predominantly nonresonant, yet can still degrade both confinement and stability. Here we introduce a systematic EFC scheme that minimizes resonant and nonresonant EF effects simultaneously, based on neoclassical torque response computed from self-consistent perturbed
equilibria. The scheme extends the method developed for designing quasi-symmetric
magnetic perturbations to the case where actual error fields are present. Application to standard ITER target
plasmas with a range of intrinsic EF scenarios demonstrates the advantages of this quasi-symmetric (QS) EFC scheme for controlling residual EFs. QS EFC consistently yields low-torque solutions while strongly suppressing resonant response, outperforming single-mode resonant overlap EFC in most cases and approaching the performance of
multimodal resonant EFC. We also show that the QS EFC solution varies only tolerably between half- and full-$I_p$ ITER scenarios, despite the greater sensitivity expected from its higher-order nature.
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All authors Gwang-Geun Seo, Jong-Kyu Park, S. J. Han, M. Dubrov
Mathematical Physics · Cross-listed from math.AP
The Two-Component Becker-Döring System: Basic Properties
Jens Scholten
The two-component Becker-Döring model is a two-dimensional coagulation-fragmentation equation that describes the dynamics of clusters built from two different types of monomers growing and shrinking through monomer interaction. We show the existence and mass conservation of solutions and give a partial result regarding uniqueness. Furthermore, we prove under the assumption of detailed balance the
entropy equation, followed by a detailed study of the
equilibrium states and relative
entropies. We can determine the minimum of all relative
entropies under sequences of fixed Type I and Type II masses and fully describe the minimising sequences in the weak*
topology.
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Earth and Planetary Astrophysics
Extracting Asteroid Physical Properties from Vera C. Rubin Observatory Science Validation Survey Data: Rotational Periods, Colors, and Taxonomies
V. Carruba, S. Greenstreet, M. Mastropietro et al. (+7 more)
The Vera C. Rubin Observatory will enable large-scale characterization of minor bodies through high-cadence, multi-band photometry. Early Science Validation (SV) observations from 2025-2026 provide one of the first extensive
datasets for
Solar System studies, but typically with sparser and more heterogeneous coverage than the Rubin First Look data, where hundreds of observations were available for well-characterized objects. In this work, we build on the methodology developed for the Rubin First Look data to extract asteroid rotation periods, amplitudes, colors, and taxonomic classifications from early Rubin SV data using multi-band (griz) photometry. Rotation periods are determined through a combination of high-order
Fourier light-curve fitting and multi-band Lomb-Scargle analysis. A unified light-curve model is then used to derive rotation-corrected colors, which are converted into taxonomic classes using calibrated color indices and spectral slopes. We validate the method on objects with sufficient observational coverage and show that preliminary physical properties can be estimated from sparse and irregular
datasets, while robust determinations require improved temporal coverage. By simulating sparsely observed data, we identify the observational conditions required for period determinations. The inclusion of z-band photometry extends traditional color-based taxonomy and improves compositional discrimination relative to gri-only analyses.
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All authors V. Carruba, S. Greenstreet, M. Mastropietro, S. Aljbaae, G. Caritá, R. C. Domingos, M. Huaman, M. M. Bala, R. D. Z. Pedroso, E. M. D. S. Delfino
Soft Condensed Matter
Superadiabatic Dynamical Density Functional Theory for One-Dimensional Brownian Hard-Rod Fluids
Jens Weimar, Daniel de las Heras and Martin Oettel
We study the relaxation dynamics of a one-dimensional system of hard rods at the level of one-body fields using superadiabatic dynamical density functional theory, and compare the results with Brownian dynamics simulations. The theory uses the exact
equilibrium excess free energy functional and incorporates superadiabatic effects from first principles via an adiabatic closure relation at the three-particle level. The predicted superadiabatic response shows very good agreement with simulation data, provided that initial-state ensemble differences between theory and simulations remain small. Furthermore, we evaluate an approximate power functional theory based on a velocity-gradient expansion, which also yields an accurate superadiabatic response, although requiring a
memory kernel extracted from simulation data.
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Nuclear Theory
Sensitivity of quasifission dynamics to the nuclear symmetry energy in $^{48}$Ca+$^{249}$Cf
C. Ross, R. Gumbel, K. Godbey et al. (+1 more)
We present a systematic study of the sensitivity of quasifission dynamics to the
nuclear symmetry energy in the $^{48}$Ca~+~$^{249}$Cf system, the reaction used for the synthesis of oganesson ($Z = 118$), spanning the full range of target orientations and angular momenta. Employing time-dependent Hartree-Fock (TDHF) calculations with four Skyrme parameterizations from the SV family that systematically vary the
symmetry energy at saturation ($a_{\text{sym}} = 28$–$34$~MeV), we perform over 500 TDHF trajectories spanning angular momenta $L = 0$–$100\hbar$ and twelve orientations of the prolate-deformed $^{249}$Cf target ($\beta = 0^{\circ}$–$165^{\circ}$ in $15^{\circ}$ steps). Shell effects in the quasifission fragments are dominated by a deformed–deformed channel: the light fragment clusters near the prolate-deformed $Z \approx 40$, $N \approx 58$ shell region (Zr/Sr), and the complementary heavy fragment populates the shape-coexistence region near $Z \approx 78$, $N \approx 121$ (Os/Pt). This channel accounts for $34$–$48\%$ of quasifission events and is geometrically incompatible with the spherical $Z = 82$, $N = 126$ closures, which are populated only at shorter contact times. The balance between the deformed and near-spherical channels depends on the
symmetry energy parameterization. These results demonstrate that quasifission observables in superheavy element formation reactions carry quantifiable sensitivity to the isovector sector of the
nuclear energy density functional.
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All authors C. Ross, R. Gumbel, K. Godbey, A.S. Umar
Optics
Fiber-based scanning levitated nanoparticle force sensor near a metalized membrane
Andrew M. Dana, Samuel J. Borden, Nia Burrell et al. (+10 more)
We describe a fiber-based dual-beam trap for dielectric nanospheres with the ability to transfer the trapped particles into a retro-reflective standing-wave trap within micron-range distances of a metallic mirror surface. We illustrate its capability for three dimensional scanning force sensing over a several square micron area of an ultra-thin gold-coated silicon nitride mirror-membrane with a total thickness of approximately 370~nm. We also demonstrate three-dimensional
laser feedback cooling and zeptonewton force resolution in high-
vacuum at micron range from the membrane, showing promise for future improved tests of
gravity at short distances and other surface force investigations. By using charged nanospheres, we expect the method may be useful for studying fluctuating patch potentials and electric field noise in the vicinity of a surface in the $\sim$ kHz to $\sim 100$ kHz frequency regime.
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All authors Andrew M. Dana, Samuel J. Borden, Nia Burrell, Chethn Galla, Alexey Grinin, Mark Nguyen, Kristina Menon, Shafaq Elahi, Katarina Boskovic Guy, Andrew Laeuger, Evan Weisman, Gambhir Ranjit, Andrew A. Geraci
History and Philosophy of Physics
$\delta$-flatness and its natural extension
Henrique Gomes
What, if anything, makes Minkowski spacetime a privileged local reference geometry in General Relativity? Recent work by \cite{WeatherallFletcher} argues: nothing. In response, I proposed a criterion of “$\delta$-flatness”, which bounds the magnitude of
tidal acceleration within a tubular neighborhood by $\delta$, and showed that Minkowski uniquely saturates the bound. Here I ask how $\delta$-flatness generalises, and distinguish two kinds of extension. Reference-metric generalisations compare physical
tidal acceleration with a reference
tidal-force term constructed from another metric. Lorentzian signature obstructs every such comparison in which the reference fails to share the lightcones of the physical metric. Criterion modifications instead build the criterion from the physical geometry alone. The space of such modifications is wide, and I focus on those closest to $\delta$-flatness, where one bounds the deviation of
tidal acceleration from a non-zero target. The minimal candidate, which I call $\delta$-MSS, has a singular limit that picks out the maximally symmetric spacetimes (Minkowski, de Sitter, Anti-de Sitter) via Schur's
theorem. A restricted variant, which compares $g$ with a conformal rescaling of itself, either collapses to $\delta$-MSS or fails to pick out a unique geometry. The chief result is that $\delta$-flatness distinguishes Minkowski with no free parameter. $\delta$-MSS, a weaker variant, picks out the maximally symmetric family at the cost of an externally supplied scalar.
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Statistical Mechanics
Observation of universal hierarchical relaxation in a quantum simulator
Jiaozi Wang, Manoj K. Joshi, Luca Capizzi et al. (+4 more)
Autocorrelation functions play a key role in the theoretical characterization of the dynamical properties of interacting many-body
quantum systems. Recently, bringing together the eigenstate thermalization hypothesis and hydrodynamics, it was theoretically predicted that the relaxation of autocorrelators can be described by the relaxation-overlap inequality, which, when saturated, predicts a hierarchy of relaxation exponents for a set of operators that are easily identified and constructed. Here, we employ a trapped-ion
quantum simulator to experimentally demonstrate it in the diffusive regime; to do so, we have extended the theory of the overlap-relaxation inequality to systems with multiple conservation laws. Our study thus opens the path to a thorough characterization of the relaxation to
equilibrium and appearance of hydrodynamic behavior in
quantum matter.
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All authors Jiaozi Wang, Manoj K. Joshi, Luca Capizzi, Rainer Blatt, Christian F. Roos, Leonardo Mazza, Dario Poletti
Materials Science
Radiation-technological processes under intense irradiation of a complex fractal medium
Zatsepin Anatoly Fedorovich, Oksengendler Boris Leonidovich, Suleymanov Sultan Khamidovich et al. (+2 more)
A fracton model of a complex medium has been constructed to study physicochemical processes for radiation-technological purposes that occur under intense irradiation. The possibility of shock-wave generation, as well as of percolation phenomena involving fractal aggregates, has been studied in the search for an ideal thermal
insulator.
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All authors Zatsepin Anatoly Fedorovich, Oksengendler Boris Leonidovich, Suleymanov Sultan Khamidovich, Ibrokhimov Rakhmatullo, Nigora Turaeva
History and Philosophy of Physics
Piezoelectricity: A Brief History of its Discovery and Physical Principles Using the Example of Low Quartz
Ruediger G. Ballas and Nataliya Koev
Piezoelectricity is a key phenomenon in solid-state physics and has significant technological relevance. In teaching, however, it is often treated either without a historical context or an explicit link to the microscopic
crystal structure, meaning that a crucial level of understanding remains untapped. This study combines the history of the discovery of piezoelectricity with its physical description within a didactically coherent framework. Building on the work of the brothers, Jacques and Pierre Curie (1880 - 1882), it demonstrated how investigations into pyroelectricity led to the identification of polarization induced by mechanical compression in hemihedral
crystals such as tourmaline and quartz. The development from early qualitative experiments towards the first quantitative determination of piezoelectric constants is traced in a structured manner. Using low quartz as an example, the microscopic cause of piezoelectricity was attributed to the asymmetric displacements of silicon and oxygen ions within the orthosilicate ion tetrahedral network. This leads to the formation of macroscopic polarization owing to uncompensated dipole moments in the
crystal lattice. The direct and reciprocal piezoelectric effects are qualitatively distinguished and discussed in the context of mechanical-electrical coupling. The article is aimed at students in physics and engineering as well as lecturers. It was conceived as a didactic review article (tutorial article) and serves as a structured introduction to the physical and historical foundations of piezoelectricity.
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Solar and Stellar Astrophysics
A Multiwavelength View of $\rho$ Oph II: Disentangling the Variability of the Multi-Star Component C
Sean J. Gunderson, Walter W. Golay, Jackson Codd et al. (+8 more)
We present a multiwavelength analysis of the
star $\rho$ Oph C, covering X-ray, optical, near-infrared, and
radio observations to test for the presence of interferometrically-detected cool
star companions. The X-ray observations from Chandra, XMM-Newton, and NuSTAR show
flare-like events lasting minutes or days in time and spectral properties consistent with those of cooler
stars instead of the primary
magnetic B
star. The near-infrared data is also consistent with the proposed trinary system properties due to the presence of CO-band heads. After removing the primary B
star's rotation, the optical data from TESS shows a residual signal at the level of 0.8 mmags, matching the variations expected from cool
stars in orbit around a bright B
star. Finally, multi-epoch
radio data reveals that $\rho$ Oph C exhibits significant large scale flux variations that are atypical for a
magnetic massive
star. Taken as a whole, the multi-epoch and -wavelength data presents a consistent picture of $\rho$\,Oph\,C as a rare trinary system composed of a hot
star and two cool
stars.
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All authors Sean J. Gunderson, Walter W. Golay, Jackson Codd, David P. Huenemoerder, Felipe Navarete, Christiana Erba, Alexandrea Moreno, John M. Cannon, Richard Ignace, Pragati Pradhan, the MACRO consortium
Mathematical Physics · Cross-listed from math.PR
Coexistence of infinite clusters for percolation and Ising model on $\mathbb{Z}^d$
Jianping Jiang and Sike Lang
For independent bond percolation on $\mathbb{Z}^d$ with parameter $p$, let $p_c^b(d)$ be the critical probability. We prove that for each $d \geq 9$, there is $\epsilon_d>0$ such that for each $p \in (p_c^b(d), p_c^b(d)+\epsilon_d)$, the complement of the infinite open cluster stochastically dominates a supercritical site percolation on $\mathbb{Z}^d$. This improves the previous results by Grimmett, Holroyd and Kozma 2014, and Bock, Damron, Newman and Sidoravicius 2020. Numerical estimates of $p_c^b(d)$ and $p_c^s(d)$ (the site critical probability) suggest that a similar
stochastic domination result holds for all $d \geq 4$. For the Ising model on $\mathbb{Z}^d$ with inverse temperature $\beta$, let $\beta_c(d)$ be the critical inverse temperature. We prove that for each $d \geq 8$, there is $\epsilon_d>0$ such that for each $\beta \in [0,\beta_c(d)+\epsilon_d)$, the $+$
spins under the minus phase stochastically dominate a supercritical site percolation on $\mathbb{Z}^d$. This improves the previous result of Aizenman, Bricmont and Lebowitz 1987. Numerical estimates of $\beta_c(d)$ and $p_c^s(d)$ suggest that a similar
stochastic domination result holds for all $d \geq 5$.
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Nuclear Theory
Exploring the Parameter Space of pvCD-Bonn Potentials under Constraints from Nuclear Saturation Properties
Ke Nan, Chencan Wang, Jinniu Hu et al. (+2 more)
We explore the parameter space of the pvCD-Bonn B potential within the relativistic Brueckner–Hartree–Fock framework under the constraints from the empirical saturation properties of symmetric
nuclear matter. We first examine the effects of the scalar-
meson and pion coupling constants. Changing the $\sigma$-
meson couplings in the $^{1}S_0$ and $^{3}S_1$–$^{3}D_1$ channels alone cannot reproduce the empirical saturation density and binding energy at the same time, whereas increasing $g_\pi$ moves the saturation point toward the empirical region. However, changing $g_\pi$ alone also affects the deuteron properties and tensor-sensitive observables. We therefore extend the parameter search by varying the $\rho$-
meson tensor coupling $f_\rho/g_\rho$ and readjusting the effective $\sigma$-
meson couplings in the $^{1}S_0$ and $^{3}P_0$ channels. Four representative parameter sets with $g_\pi^2/4\pi=14.7$–15.0 give deuteron properties close to the experimental values and maintain a reasonable description of the main
neutron–
proton phase shifts and differential cross sections at $E_{\rm lab}=50$ and 212 MeV. Their saturation densities lie in the range $0.159$–$0.161~\mathrm{fm}^{-3}$, with saturation energies between $-15.00$ and $-15.38~\mathrm{MeV}$. For the interactions obtained by varying $g_\pi$, the
neutron-
star mass–radius relations show only a weak dependence on the pion coupling, with maximum masses of about $2.24$–$2.28\,M_\odot$ and radii of about $12.3$–$12.6~\mathrm{km}$ at $1.4\,M_\odot$. These results show that including the $\rho$-
meson tensor coupling and partial-wave-dependent $\sigma$-
meson couplings provides a better balance between free-space two-nucleon observables and
nuclear-matter saturation properties than varying the pion coupling alone.
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All authors Ke Nan, Chencan Wang, Jinniu Hu, Ying Zhang, Hong Shen
Materials Science
Anisotropic Magnetic and Transport Properties of RAlGe (R = Y, Gd-Tm, Lu)
Tyler J. Slade, Lin-Lin Wang, Sergey L. Bud'ko et al. (+1 more)
We grew single
crystals of the RAlGe family for R = Y, Gd-Tm, Lu and characterized them with powder X-ray diffraction, temperature dependent specific heat measurements as well as temperature and field dependent resistance and magnetization measurements. These RAlGe materials crystallize in an orthorhombic Cmcm
crystal structure in which the R atoms occupy a position with $m$2$m$ point
symmetry. We find that when R is a moment bearing rare earth atom, the RAlGe materials order antifferomagnetically at $T_{\text{N}}$ ranging from 5 K (TmAlGe) to 39 K (TbAlGe). A second, lower temperature
antiferromagnetic transition is also detected in the range 6-8 K for R = Tb-Ho, but no lower transition is observed (for T above 1.8 K) for R = Er, Tm. The R = Tb-Tm members show evidence for strong
crystal field effects influencing the physical properties, where the
crystal field favors an easy $a$-axis for R = Tb-Ho and an easy $b$-axis for R = Er, Tm. Of these compounds, strongly uniaxial behavior is observed for DyAlGe and TmAlGe. At T = 2 K, rich metamagnetism is observed when the external field is applied along the $a$-axis for R = Tb–Ho, whereas a single metamagnetic transition is observed (up to 70 kOe) with the field along the $b$-axis when R = Er and Tm. All RAlGe materials show metallic transport behavior and have moderate positive magnetoresistance up to 60-150 % at 2 K superimposed on top of metamagnetic features. The field dependent magnetization measurements on non-moment bearing YAlGe show clear de Haas-van Alphen oscillations, indicating the
Fermi surface includes small, high mobility pockets.
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All authors Tyler J. Slade, Lin-Lin Wang, Sergey L. Bud'ko, Paul C. Canfield
Materials Science
Unified description of exciton, phonon and plasmon dispersions in 2D materials from an optical conductivity approximation
Alberto Guandalini, Andrea Ferretti, Daniele Varsano et al. (+2 more)
The modified Coulomb interaction in two-dimensional (2D) materials gives rise to unique, non-analytic low-momentum dispersions of
excitons,
phonons, and plasmons. Here, we describe the 2D dispersion of longitudinal excitations by introducing the optical conductivity approximation (OCA), a unified framework that evaluates the finite-q longitudinal response probed by electron energy-loss spectroscopy (q-EELS) by only using the q = 0 optical conductivity. By doing so, the approach demonstrates that the linear dispersion of all the above mentioned excitations is mainly due to the form of the 2D macroscopic Coulomb interaction rather than to the dispersion of the underlying band structure. Applying this approach to hexagonal boron nitride and
graphene we accurately reproduce the energy and intensity dispersions of the hBN longitudinal-optical
phonon and low-energy bright
excitons, along with the
graphene pi-plasmon. Our work also provides an efficient computational scheme to describe low momentum EELS data without the need to calculate the response functions at dense moment
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All authors Alberto Guandalini, Andrea Ferretti, Daniele Varsano, Paolo Barone, Francesco Mauri
High Energy Astrophysical Phenomena
Observational signatures of warped accretion flows in tidal disruption events
Andrew Mummery and Eliot Quataert
We analyze the possible observational signatures and
evolution of global warps in the
accretion flows produced in
tidal disruption events. These warps are driven by Lense-Thirring torques resulting from the misalignment of the disk's rotation axis and the black hole's
spin axis. In a previous paper we argued that these global warps should be generically present in TDE
accretion flows as they enter a late-time thin disk phase of
evolution. We isolate three possible observational signatures of warps: (i) anomalous (reddened) late time optical colors, resulting from irradiative heating of the warped outer disk by the inner flow, (ii) delayed X-ray rises, resulting from the inner disk being slowly revealed to a distant observer as the warped flow gradually aligns with the
spin axis, and (iii) reverberation of turbulent X-ray
flares into optical/UV frequencies as the inner disk heats the outer disk during a flaring state. We present preliminary observational evidence that all three effects may have already been observed in TDE systems. Observations of TDEs may well offer the cleanest astronomical signatures of the strong-
gravity effects which cause disk warping, and provide unique constraints on the poorly understood
evolution of warped
accretion disks.
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Quantum Gases
Microscopic theory of the collective optical response of dilute atomic clouds at finite temperature
Tanja Schoger, Romain Pierrat and Nicolas Cherroret
At low temperature, collective light-induced dipole-dipole interactions are known to strongly reshape the optical response of atomic clouds, revealing the breakdown of the independent-scattering picture as the density increases. While thermal motion is generally believed to progressively suppress these interactions, the microscopic mechanisms behind this suppression remain largely unexplored. Here, we develop a microscopic theory of the optical response of a dilute atomic gas at finite temperature, explicitly accounting for atomic ballistic motion during the recurrent-scattering events associated with the collective corrections. Using a diagrammatic approach for scalar light, we derive the collective contribution to the optical permittivity and characterize its behavior across the full temperature range. We find that thermal corrections scale as $\sim T$ at low temperature, while recurrent-scattering contributions are suppressed as $\sim T^{-3/2}$ at high temperature. Our predictions are confirmed by extensive coupled-dipole simulations that explicitly account for atomic motion. These simulations also reveal the inaccuracy of the modified frozen-dipole approximation commonly used to treat thermal effects. Finally, extending our theory to vector light, we provide a complete picture of how the resonance shift continuously evolves from the collective Lamb shift at low temperatures to the classical Lorentz-Lorenz shift at high temperatures.
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Earth and Planetary Astrophysics
VLTI/MATISSE observations of the hot dust around $\beta$ Pictoris: Observing faint objects with MATISSE
P. Priolet, J.-C. Augereau, J. Milli et al. (+32 more)
Context: Hot exozodiacal
dust has been detected around approximately 20% of nearby main-sequence
stars, indicating that it is a common feature of extrasolar planetary systems. However, its spatial distribution and grain properties remain poorly understood. Aims: We aim to show that the spatial distribution of hot
dust around beta Pictoris, an iconic planetary system with two known
planets and a population of exocomets, can be constrained through a detailed analysis of optical long-baseline interferometry data. Methods: We obtained L-band observations at approximately 3.5 microns of beta Pictoris with MATISSE at the VLTI. We developed a method to assess correlations in the visibility measurements by estimating the full data covariance
matrix, and modeled the circumstellar emission with
geometric brightness distributions. Results: We detect circumstellar emission around beta Pictoris consistent with hot exozodiacal
dust. Modeling the emission with and without accounting for data correlations demonstrates their significant impact on the inferred
dust properties. The best-fit model reveals a compact (approximately 0.05 au), highly inclined
dust structure near the sublimation radius, misaligned by approximately 60 degrees on the sky with respect to the extended edge-on outer disk. It contributes approximately 4%-7.5% of the total flux at 3.4 microns and is composed of submicron-sized grains. The data are also compatible with an additional
dust component near 1 au. Conclusions: For beta Pictoris, the two-decade-old paradigm placing hot exozodiacal
dust near the sublimation radius and consisting of submicron-sized grains finds observational support in the detailed analysis of MATISSE data. The misalignment with the known debris disk further supports a link to exocometary activity.
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All authors P. Priolet, J.-C. Augereau, J. Milli, A. Matter, B. Lopez, H. Beust, J. Varga, P. Boley, W.-C. Danchi, L. Foteini, T. Henning, M. Houllé, M. Letessier, F. Millour, J. Scigliuto, G. Weigelt, S. Wolf, O. Absil, J.-P. Berger, Y.-I. Bouarour, G. Bourdarot, D. Defrère, C. Desgrange, J.-B. Le Bouquin, D. Iglesias, T. A. Stuber, P. Berio, F. Bettonvil, P. Cruzalèbes, M. Heininger, J. W. Isbell, S. Lagarde, A. Meilland, R. Petrov, S. Robbe-Dubois
Astrophysics of Galaxies
How Magnetic Fields Regulate Cooling and Mixing in Turbulent Radiative Mixing Layers
Rajsekhar Mohapatra, Lachlan Lancaster, Drummond Fielding et al. (+2 more)
Turbulent radiative mixing layers (TRMLs) are expected wherever hot and cold gas move past one another, including in the
solar corona,
galactic winds, and cold filaments in
galaxy clusters. These environments are often magnetized, but
magnetic effects on mixing and cooling remain less well understood than in the hydrodynamic (HD) case. We present magnetohydrodynamic (MHD) simulations of TRMLs at resolutions up to $1024 \times 2048^2$, spanning fields aligned with and transverse to the shear, and polarity-reversing configurations in which oppositely directed fields form current sheets at the interface. Even initially weak hot-phase fields, with $\mathcal{M}_{\rm A,shear}\equiv v_{\rm shear}/v_{\rm A}\sim14$, reduce the mass and enthalpy flux and radiative cooling rate by up to an order of magnitude relative to HD.
Magnetic tension weakens turbulent motions, reducing both the
diffusion of hot gas into the layer and the folding of the cooling surface. Transverse fields suppress cooling somewhat more strongly than shear-aligned ones, although a transverse field exerts no tension against the initial linear instability. Polarity reversal changes the morphology of the cooling gas without restoring HD-like mixing. The dependence on the Damköhler number is similar to the HD case, but the degree of suppression is dependent on the initial field orientation. The net cooling rate appears resolution-independent in HD but declines with resolution in MHD, and has not converged, so our suppression factors are lower limits.
Magnetic fields therefore strongly regulate cooling and mixing in multiphase gas, and quantitative predictions require careful treatment of transport processes.
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All authors Rajsekhar Mohapatra, Lachlan Lancaster, Drummond Fielding, Eliot Quataert, Greg L. Bryan
Optics
Real-Time Event-Based Optical Camera Communication at 80 kbit/s over a 320 m Outdoor Link with 120{\deg} Field-of-View
Francesco Nardo, Peter Krötz, Ricardo Barrios et al. (+1 more)
We demonstrate an event-based optical camera communication system using a 120{\deg} field-of-view sensor. In daylight, three transmitting nodes achieve an aggregate 240 kbit/s, with individual links reaching 106 kbit/s at 1 m and 80 kbit/s at 320 m. Our results, establish a new baseline for event-OCC.
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All authors Francesco Nardo, Peter Krötz, Ricardo Barrios, Sebastian Randel
Solar and Stellar Astrophysics
Quantum Phase Transitions in Nuclei and the Origin of Rhodium
P. Agarwal, H. Schatz, A. Francis et al. (+3 more)
The astrophysical rapid
neutron capture process (r-process) is a major nucleosynthesis process responsible for the production of elements heavier than copper. Prominent features in the observationally inferred r-process abundance distributions provide critical clues for astrophysical conditions and possible r-process sites. The lack of clear features for the r-process elements lighter than tellurium has led to a broad range of proposed possible scenarios and alternative processes that may produce these elements. Here we show that the enhancement found in the
solar system of rhodium and ruthenium isotopes compared to neighboring isotopes can serve as such a feature. The enhancement can be traced back to sudden changes in shape of unstable rare isotopes in the path of the light element r-process. Such shape changes have been described as
quantum phase transitions. This finding points to r-process scenarios with relatively high
neutron densities and temperatures for the origin of rhodium and ruthenium in the
solar system. Rhodium and ruthenium abundances observed in r-process enhanced
stars can now be used as diagnostics for the r-process conditions that produce these lighter r-process elements. Observational data for these elements indicate that different types of r-processes may have operated in the early
Galaxy, and that the conditions do not necessarily align with the weak and main r-process classifications used in the past.
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All authors P. Agarwal, H. Schatz, A. Francis, F. Montes, B. Pol, L. Roberts
General Relativity and Quantum Cosmology
Environmental Imprints of Dark Matter and Accretion Disks on Eccentric EMRIs around Kerr Black Holes
Hai-Chao Yuan and Yong Tang
Extreme-mass-ratio inspirals (EMRIs), systems in which a
stellar-mass compact object spirals into a supermassive black hole ($M_1$), are
prime targets for the space-based gravitational-wave interferometers and are acutely sensitive to their astrophysical environment. We quantify the joint imprint of a dark matter (DM) spike and an
accretion disk on the waveforms of eccentric, equatorial Kerr EMRIs, integrating four modular effects—DM dynamical friction, DM self-
gravity, Newtonian
accretion-disk torques, and disk self-
gravity—into a fifth post-Newtonian (5PN) augmented analytic kludge (AAK) waveform model, and assess their measurability via a Fisher-
matrix analysis. The DM dynamical-friction dephasing peaks at $M_1\sim 10^6\,M_\odot$, reaching $\sim 10^2$–$10^3\,\mathrm{rad}$; there the DM spike slope is measurable to sub-percent precision and both DM channels are unambiguously detectable, while omitting DM biases the intrinsic parameters significantly. At $M_1\gtrsim 10^8\,M_\odot$ the DM and disk self-
gravity channels dominate their dissipative counterparts. The disk parameters remain degenerate across the explored parameter space, since the supersonic regime dominates the inspiral and the subsonic-to-supersonic transition only mildly weakens this degeneracy without lifting it; a combined DM$+$disk analysis further reveals a cross-sector degeneracy between the DM slope and the disk parameters. This physical degeneracy, reflected in the near-singular Fisher
matrix, implies that independently measuring the disk parameters requires a relativistic torque model or an electromagnetic counterpart.
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