Earth and Planetary Astrophysics
The size and mass distribution of cold classical TNOs for $5<H<13$
Gary M. Bernstein, Wesley C. Fraser, Marielle R. Eduardo et al. (+7 more)
The cold classical trans-Neptunian objects (CCs) are the only observable in situ population of planetesimal remnants believed to have escaped collisional grinding. Recent JWST observations make it possible to fit the differential absolute magnitude distribution $dN/dH$ of the CCs from $5<H_r<13,$ and infer the differential mass distribution $dN/dM$ across $\ge5$ orders of magnitude in mass. We find $dN/dM$ well fit by a lognormal distribution, and equally well by a generalized $\Gamma$ distribution or a double power law. The maximum fraction of the total CC mass per log interval in $M$ is in bodies near 75~km diameter, or $\approx10^{-7.5}M_\oplus.$ Extrapolation of the fitted $dN/dH$ functions to $H_r>13$ is unwise, as the different analytic forms diverge. It remains unclear if $dN/dH$ turns over at faint $H.$ The uncertainty in the total mass of the CC belt is dominated by uncertainty in the relation between $M$ and $H$. A calibration using CC binaries suggests a total CC mass of 1.7–2.7$\times10^{-3}\,M_\oplus.$ A trend toward lower density and/or higher albedo for smaller bodies may be present in the data, and would lower the estimated total CC mass. Qualitative comparison of the derived mass distribution to the results of numerical simulations of the streaming instability (SI) suggest the simulations produce $dN/dM$ distributions that are more sharply peaked, and steeper at the bright end, than the CCs. Such differences could be ascribed to inhomogeneous formation conditions in the classical belt that are not yet included in modeling. The variety and uncertainty of $dN/dM$ derived from state-of-the-art SI simulations currently preclude any definitive test of the SI hypothesis.
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All authors Gary M. Bernstein, Wesley C. Fraser, Marielle R. Eduardo, William M. Grundy, Bryan Hilbert, Matthew J. Holman, Anastasia N. Morgan, Kevin J. Napier, John A. Stansberry, David E. Trilling
Soft Condensed Matter
Discretization strategies for colloidal particles in multiparticle collision dynamics simulations
Michaela Bush and Michael P. Howard
Discrete models are frequently used in multiparticle dynamics simulations to capture hydrodynamic interactions between colloidal particles and the solvent as well as to represent anisotropic pairwise interactions between colloidal particles; however, there is currently limited guidance on how to reliably parameterize these models. Here, we first compare strategies for selecting the density and mass of discrete surface sites used to couple colloidal particles to the solvent, finding that using a minimum of 2 sites per unit area with a scheme that matches the total mass and moment of inertia for a neutrally buoyant solid particle produces reliable and accurate results for the transport properties of colloidal particles at both infinite dilution and in suspension. We then compare strategies for representing the excluded volume of nearly-hard shape-anisotropic colloidal particles using a collection of discrete interaction sites with isotropic repulsion, finding that having a discrepancy between the nominal volume and the excluded volume of the particle can significantly affect suspension transport properties. This discrepancy can be mitigated by placing the interaction sites inside and tangent to the surface of the colloidal particle. We expect these findings to help construct discrete models for colloidal particles with less sensitivity to parameterization.
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Pattern Formation and Solitons
Reduction Based Dynamical Systems Analysis of Nonlinear Wave Equations: A Review
Naresh Saha and Arnob Ray
Nonlinear wave equations exhibit rich interplay among dispersion, nonlinearity, coupling, dissipation, and external forcing, producing diverse coherent and complex wave structures. Although exact travelling-wave solutions provide analytical
benchmarks, their construction alone does not reveal underlying phase-space, bifurcations, stability, or responses to perturbations. This review presents a reduction-based methodological framework connecting nonlinear partial differential equations(PDEs) to reduced dynamical systems, invariant phase-space structures, exact waveform reconstruction, stability analysis, and verification in PDEs. Its applicability and limitations are examined across Schrödinger-type, coupled, nonparaxial, dissipative,
magnetic, shallow-water, and fractional wave equations. Particular emphasis is placed on correspondence between analytical waveforms and invariant orbits.
Equilibria, periodic trajectories, homoclinic orbits, and heteroclinic connections geometrically represent constant, periodic, localized, and front-like structures, respectively. This review distinguishes existence and stability of invariant structures from onset of chaos, emphasizing complementary diagnostics rather than reliance on phase-portraits or finite-time indicators alone. Major methodological gaps include incomplete parameter-space characterization, weak correspondence between reduced models and full-PDE dynamics, ambiguities in generalized and fractional formulations, limited robustness analysis, inadequate numerical reproducibility, and insufficient links to experimental observables. The framework prioritizes physical admissibility, stability, robustness, and predictive relevance over generation of additional formal solutions. It supports reliable nonlinear wave prediction, stability assessment, control, and system design in fluid, optical,
plasma, and other nonlinear physical systems.
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Astrophysics of Galaxies
Active galactic nucleus activity in brightest cluster galaxies at intermediate redshifts in Sunyaev-Zel'dovich–selected clusters
N. Hatamkhani, R.E. Skelton, J. Delhaize et al. (+4 more)
Context. Brightest cluster
galaxies (BCGs) host powerful active
galactic nuclei (AGNs) and help regulate the heating–cooling balance of the intracluster medium. While
radio-mode feedback is well established locally, its prevalence at intermediate
redshifts remains poorly constrained. Aims. We investigate the incidence,
accretion state, and host-
galaxy properties of AGNs in BCGs in Sunyaev–Zel'dovich (SZ)-selected clusters at $0.3 < z < 0.8$, testing dependences on
cosmic epoch, cluster mass, and dynamical state. Methods. We analyse 171 BCGs from the Atacama Cosmology
Telescope SZ catalogue, combining Southern African Large
Telescope spectroscopy, WISE mid-infrared photometry, and Rapid ASKAP Continuum Survey
radio data with X-CIGALE modelling to derive
stellar masses,
star formation rates, and Eddington-scaled
accretion rates. Results. Thirty-eight BCGs (22%) host
radio-loud AGNs. Only two ($\sim$5%) are high-excitation
radio galaxies; the remainder are low-excitation systems. Most AGNs have low Eddington ratios ($-3 \lesssim \log_{10}\lambda_{\mathrm{Edd}} \lesssim -1$), consistent with radiatively inefficient
accretion.
Accretion efficiency increases with
redshift, while correlations with cluster mass and dynamical state are weak.
Radio luminosity is independent of cluster mass. Compared to field
radio AGNs, BCG
radio-loud AGNs have similar
radio powers but are hosted by
galaxies $\sim0.8$ dex more massive. Conclusions. BCG
radio-loud AGNs at $0.3 < z < 0.8$ are predominantly low-excitation, radiatively inefficient systems, indicating that maintenance-mode
accretion was widespread in massive clusters ($M_{500c} \simeq 3.2 \times 10^{14},M_\odot$) by $z \sim 1$.
Accretion appears regulated primarily by fuel availability and
cosmic evolution rather than global cluster properties, while the cluster environment mainly sets the host-
galaxy mass scale.
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All authors N. Hatamkhani, R.E. Skelton, J. Delhaize, M. Hilton, S.I. Loubser, N. Gupta, K. M. Mogotsi
High Energy Physics (Phenomenology)
Bottomonium suppression with a machine-learning-informed Debye mass
Ajaharul Islam, Shibo Chen, Fu-Peng Li et al. (+2 more)
Motivated by recent progress in data-driven approaches, we introduce a machine-learning (ML)-informed Debye mass, extracted from
lattice-informed inputs, exclusively in the complex-valued heavy-
quark Kent State University (KSU) potential. The resulting complex potential is used to solve the real-time Schrödinger equation within the
quantum trajectories (QTraj) framework for the
evolution of bottomonium in the
quark-
gluon plasma. We then compute the
nuclear modification factors and double ratios for bottomonium $\Upsilon(1S)$, $\Upsilon(2S)$, and $\Upsilon(3S)$ states in Pb-Pb collisions at $\sqrt{s_{NN}} = 5.02$ TeV. We compare our ML-induced results with those from the original KSU model and with experimental measurements from ALICE, ATLAS, and CMS collaborations. We find that the machine-learned Debye mass leads to improved agreement with data, particularly for excited states, highlighting the utility of machine learning in modeling in-medium QCD effects.
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All authors Ajaharul Islam, Shibo Chen, Fu-Peng Li, Long-Gang Pang, Guang-You Qin
General Physics
Sector-Resolved Bayesian Model Averaging for DESI-Era Cosmology
Slava G. Turyshev
We present a quotient-space
Bayesian formulation for DESI-era anomaly interpretation. Given a pattern-labeled catalog with map \(i\mapsto \Act(i)\), the induced posterior \(p(\Act\mid D)\), sector inclusion probabilities \(P_\alpha\), co-activation probabilities \(P_{\alpha\beta}\), and grouped Bayes factors \(B_\alpha(D)\) are exact summaries over predeclared physical activation events. Pairwise comparisons such as \(\lcdm\) versus \(\wacdm\) remain ordinary Bayes-factor tests between specified families; the quotient construction addresses the coarser question of which physical sector carries posterior support when different sectors are represented by unequal numbers of catalog elements. We derive a sector-resolved DESI-CMB-SN likelihood specification for late-time background, early-time ruler,
supernova calibration, perturbation, and gravitational-wave propagation sectors. The construction includes an Alcock-Paczynski/isotropic-scale BAO decomposition, a pure-ruler projection, analytic marginalization of low-rank
supernova calibration modes, Fisher-normalized sector priors, inactive-sector leakage tests, log-evidence uncertainty propagation, and prior/sector-partition diagnostics. The result is a quantitative procedure for reporting model-comparison support at the level of physically interpretable sectors.
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Earth and Planetary Astrophysics
The Luminosity Function of Ultra-Faint Trans-Neptunian Objects Detected by JWST
Marielle R. Eduardo, Anastasia N. Morgan, Wesley C. Fraser et al. (+8 more)
We present a definitive discovery of 27 trans-Neptunian objects (TNOs) using the Near-Infrared Camera (NIRCam) aboard the James Webb Space
Telescope (JWST). By employing a shift-and-stack technique and a machine learning network geared specifically to identifying false-positive detections in JWST images produced through the shift-and-stack process, we achieved a 40% detection threshold of $m_{F150W2}=28.8$ mag (corresponding to $m_r\sim29.8$ mag) across a sky area of $0.05 \ \text{deg}^2$. This marks the deepest
Solar System survey to date, reaching magnitudes that allow us to explore never-before-seen regions of the TNO size distribution. Our faintest detection has $m_{F150W2}=29.3$ mag and diameter of $\sim10$ km (assuming 15% albedo). Within our sample, we find that both the Cold and Hot TNO subpopulations exhibit a power-law slope. The distribution of apparent magnitudes of our nominal sample (detections at all epochs) are well fit by a single power law $dN/dm \propto 10^{\alpha m}$ with $\alpha=0.29^{+0.08}_{-0.07}$. The dynamically hot and cold subsamples in our discovery set are consistent with the same power law, suggesting that the planetesimal formation process yields similar slopes despite the differing disk conditions at the presumed $\sim25$ and $\sim45$~au formation regions of the two populations.
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All authors Marielle R. Eduardo, Anastasia N. Morgan, Wesley C. Fraser, David E. Trilling, Gary M. Bernstein, John A. Stansberry, Bryan Hilbert, Matthew J. Holman, William M. Grundy, Thomas L. Storer, Kevin J. Napier
Pattern Formation and Solitons · Cross-listed from math.AP
Speed and stability of segregated waves in a pressure-based model of heterogeneous cell populations
Carles Falcó, Rebecca M. Crossley, Martina Conte et al. (+1 more)
We consider a minimal pressure-based model of heterogeneous
cell populations consisting of proliferative and non-proliferative
cells with different mobilities. The model is formulated as a system of reaction–cross–
diffusion equations describing the spatio-temporal dynamics of the
cell densities. The model is known to admit one-dimensional travelling wave solutions with strictly segregated components: non-proliferative
cells occupy a finite region at the leading edge, while proliferative
cells remain at the rear. However, the speed, parameter dependence, and stability of these waves remain poorly understood. In this work, we derive an almost explicit variational bound on the wave speed by reformulating the problem as a free-boundary problem for a generalised porous–Fisher equation. The estimates we obtain apply to general pressure laws and growth kinetics, agree closely with the results of numerical simulations, and become sharp in the incompressible limit, where we formally recover a fully explicit characterisation of the wave speed. We then analyse the stability of the waves to show that segregated waves are stable only when non-proliferative
cells are more mobile than proliferative
cells. Finally, motivated by numerical observations of finger-like protrusions, we investigate the stability of incompressible segregated circular waves through asymptotic shape-perturbation analysis. This yields explicit expressions for the pressure, interface velocity, and growth rates of angular modes, thereby making evident the destabilisation mechanisms that may lead to the emergence of fingering instability. Interestingly, we find that, in contrast with the one-dimensional case, the stability of such circular waves is not determined solely by the relative value of the mobility coefficients, and thus instabilities may arise irrespective of which
cell type has the larger mobility.
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All authors Carles Falcó, Rebecca M. Crossley, Martina Conte, Tommaso Lorenzi
High Energy Physics (Theory)
M5 Instantons in ABJM
Jieming Lin, Jesse van Muiden and Zihan Wang
We study the existence of supersymmetric M5-brane instantons in asymptotically AdS$_4 \times S^7/\mathbf{Z}_k$ geometries of M-theory, dual to the ABJM theory. The supersymmetric
embeddings of these instantons are determined by the M5-brane $\kappa$-
symmetry, which forces them to localise to the equivariant fixed points in the asymptotically AdS$_4$ geometry, and wrap $(S^3\times S^3)/\mathbf{Z}_k $. At the
quantum level we find that the one-loop partition function of these instantons vanishes, suggesting that the bulk partition function is instead to be expanded in terms of supergravity modes and M2-brane instantons, in line with known results for the $S^3$ partition function of the dual ABJM theory.
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High Energy Physics (Phenomenology)
Mohammad Aghaie and Alessandro Strumia
The LZ experiment reported a
nuclear recoil with anomalous energy $E_R=248$ keV, around the typical
neutron motion in xenon. This motivates interpreting the event as the disappearance of a bound
neutron, either through spontaneous decay or a dark-matter-induced reaction. If the energy released is large, the predicted
recoil spectrum is broad around the observed value; only $\sim10\%$ of xenon events avoid extra
nuclear activity; the disappearance rate is target-independent and mildly constrained by oxygen experiments. In the special case of near-threshold DM-induced
neutron disappearance, it can be open in xenon and closed in oxygen, the quiet fraction rises to $\sim30\%$, the
recoil spectrum turns into lines.
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Plasma Physics
On the modeling of oblique firehose instabilities in regularized Kappa plasmas using ALPS
D. L. Schröder, M. Lazar, H. Fichtner et al. (+2 more)
In-situ measurements in space
plasmas indicate that the velocity distributions of charged particles are not in thermal
equilibrium, deviating from a standard Maxwellian mainly due to anisotropies and suprathermal populations which enhance high-energy tails. Although the Standard ąppa}-Distribution (SKD) is well established in modeling these non-
equilibrium distributions, its application is often viewed controversially due to certain unphysical implications, in particular divergent velocity moments. To address these issues, the Regularized ąppa}-Distribution (RKD) was introduced. Such advanced, in general anisotropic RKDs are invoked here for the first time to investigate oblique firehose instabilities, including those induced by the temperature anisotropy of electrons and
protons, the dominant species in space
plasmas. In weakly collisional
plasmas, both of these instabilities are expected to play significant roles in the self-regulation of the macroscopic properties of space
plasmas (e.g. the expanding
solar wind) reported by observations. Is not yet possible to resort to a general dispersion tensor related to RKD
plasmas (whose derivation is still a challenge), instead the Arbitrary Linear
Plasma Solver (ALPS) is exploited here. The unstable solutions obtained for the already established Maxwellian & SKDs successfully validate the capability of ALPS. For RKDs, the instabilities confirm the stimulating effect of suprathermal populations, with lower ąppa} values generally enhancing the firehose growth rates. For the oblique electron firehose instability, RKDs substantially modify the competition between periodic & aperiodic branches only at intermediate angles & can sustain significantly increased growth rates of especially aperiodic modes at highly oblique propagation beyond both the Maxwellian unstable regime & the one that is accessible with SKDs.
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All authors D. L. Schröder, M. Lazar, H. Fichtner, K.G. Klein, D. Verscharen
Quantum Physics
Near-Optimal Quantum Lower Bounds for Convex Optimization via Fourier Rank
Brandon Augustino, Shouvanik Chakrabarti, Enrico Fontana et al. (+4 more)
We establish a linear
quantum query lower bound for high-accuracy convex optimization over an explicit family of $n$-dimensional ellipsoids. We focus on linear optimization with an explicitly given objective, where the feasible set is accessed through a membership oracle. We show that any
algorithm that, for every unit linear objective, returns an exactly feasible point with additive objective error $\Theta(n^{-1/2})$ requires $\Omega(n)$ membership queries, where the ellipsoids are contained in the unit ball. The same lower bound can be shown to hold if the returned point is only required to be approximately feasible, within $\Theta(n^{-3/2})$ distance from the feasible set. This resolves an open question posed by Chakrabarti, Childs, Li, and Wu~(
Quantum, 2020) and by van Apeldoorn, Gilyén, Gribling, and de Wolf~(
Quantum, 2020). Coupled with the upper bounds in these papers, the query complexity of high-accuracy convex optimization is characterized tightly up to logarithmic factors. The proof is built around a lower bound for determinant computation that is derived via a novel
polynomial method based on
Fourier-rank. In the continuous
matrix phase-query model, computing the determinant of a real $n\times n$
matrix requires at least $n/2$
matrix-vector product queries. The construction also yields an $\Omega(n)$ phase-query lower bound for estimating the minimum
eigenvalue of a real symmetric $n\times n$
matrix to additive accuracy $\Theta(n^{-2})$. These results extend the determinant and minimum-
eigenvalue lower bounds of Childs, Hung, and Li~(ICALP 2021) from finite fields to the real-valued setting. Based on the same constructions, we also prove an $\Omega(\min\{\sqrt\kappa,n\})$ gradient-query lower bound for constant-accuracy optimization of $1$-strongly convex and $\kappa$-smooth functions, which is optimal up to a logarithmic factor.
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All authors Brandon Augustino, Shouvanik Chakrabarti, Enrico Fontana, Dylan Herman, Junhyung Lyle Kim, Guneykan Ozgul, Nadezhda Voronova
Chemical Physics
Balanced and broadly-normed meta-generalized gradient approximation
Yanyong Wang, Chandra Shahi, John P. Perdew et al. (+1 more)
Conventional semi-local density functional approximations for the exchange-correlation energy systematically underestimate fundamental band gaps. Advanced meta-generalized gradient approximations (meta-GGAs) can partially overcome this limitation through their orbital dependence via the kinetic energy density. In principle, the flexible meta-GGA form should allow for balanced performance across diverse properties. However, atomization energies, reaction barrier heights, and
lattice constants, as well as band gaps, exhibit different sensitivities to the large parameter space of meta-GGA functionals. In this work, we explore the space of appropriate norms that guide the r$^2$SCAN-type functional construction through the interpolation function connecting two fundamental paradigms: the one-electron limit and the uniform electron gas limit. We introduce local modifications to a strongly-smoothed interpolation function and investigate their impact on functional performance. To further probe the limits of the meta-GGA framework, we include
spin-unpolarized bonded systems among the set of norms. The resulting bonded-norm bn-r$^2$SCAN meta-GGA achieves balance: band-gap predictions approaching the accuracy of the ultra-nonlocal LAK meta-GGA and
lattice constants of nearly r$^2$SCAN accuracy.
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All authors Yanyong Wang, Chandra Shahi, John P. Perdew, Adrienn Ruzsinszky
Quantum Physics
Semidefinite extension complexity of the separable set, with applications to approximate disentanglers
Sevag Gharibian, Carsten Hecht and Dorian Rudolph
We prove quantitative lower bounds on the semidefinite extension complexity of the set of separable
quantum states on $\mathbb{C}^d\otimes\mathbb{C}^d$. We consider semidefinite programs (SDPs) that approximate the maximum acceptance probability of a measurement over separable states, the optimization problem underlying QMA(2). In the extended-formulation model of Harrow, Natarajan, and Wu (HNW), all measurements share a common feasible region and an objective-independent
embedding of product states that exactly reproduces their acceptance probabilities. For every $0<\theta<2/7$, there are constants $c_\theta,a_\theta>0$ such that, for sufficiently large $d$, any such SDP with uniform additive error $0<a\le a_\theta$ has size at least $d^{c_\theta\min\{a^{-1/3},d^\theta\}}$. The bound applies at sufficiently small constant error, is superpolynomial in $d$ whenever $a=o(1)$, and becomes $d^{\Omega(d^\theta)}$ when $a\le d^{-3\theta}$, improving HNW's quasipolynomial bound at inverse- square error. The same bound holds for any SDP-representable convex set of states that contains all separable states and lies within trace distance $a$ of them, giving a quantitative counterpart to Fawzi's
theorem that the separable set has no exact semidefinite representation. Our proof combines the quantitative pseudo-density
theorem of Lee, Raghavendra, and Steurer with explicit block-positive operators and Chebyshev amplification. Our main results are supported by Lean proofs.
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High Energy Astrophysical Phenomena
Wolf-Rayet stars and black holes: mass distributions and evolutionary connection
I.A. Shaposhnikov, K.A. Postnov and A.M. Cherepashchuk
The form and relationship between the mass distributions of Wolf-Rayet
stars and black holes are analyzed using a direct method for estimating the distribution function from a sample of mass values with individual distributions obtained from current observations. It is shown that, taking into account the mass loss of WR
stars by the end of this evolutionary stage, the mass distribution of black holes is close to that of the CO-cores of WR
stars before gravitational collapse, $M_\mathrm{BH}\simeq M_\mathrm{CO}$.
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High Energy Astrophysical Phenomena
Detection of episodic Ultra-fast Outflows in the Low-luminosity quasar Mrk 205 using XMM-Newton data
César Ivan Victoria-Ceballos, Anna Lia Longinotti, Yair Krongold et al. (+3 more)
Ultra-fast
outflows (UFOs) from Active
Galactic Nuclei (AGN) are winds which reach velocities up to 0.3c, and show mass
outflow rates of 0.01-1 $M_{\odot} yr^{-1}$ and kinetic energies of $10^{42-45}$ erg/s. Their extreme properties allow UFOs to carry substantial kinetic power, sufficient to drive AGN feedback by injecting energy and momentum into the interstellar medium, regulating the host
galaxy evolution and the supermassive black hole growth. In this work, we present a detailed analysis of XMM-Newton X-ray spectra of the low-luminosity
quasar Mrk205. We find evidence of multi-component ultra-fast
outflows, traced by two components detected in the high-resolution data, showing velocities in the range of $\sim$0.07c to $\sim$0.1c. In addition, we marginally detected an ultra-fast
outflow feature in the Fe K band. According to our analysis, Mrk 205 shows episodes of wind launches, rather than persistent winds. We further discuss whether the energy carried by the UFOs in Mrk 205 is capable of producing significant feedback on its host
galaxy.
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All authors César Ivan Victoria-Ceballos, Anna Lia Longinotti, Yair Krongold, Giorgio Lanzuisi, Miriam Gudiño, Armando Lara-DI
Chaotic Dynamics · Cross-listed from q-bio.PE
Selection Rules for Species Coexistence in a Hierarchical May-Leonard Model
Rakesh Samanta, Shraosi Dawn, Sk Jahiruddin et al. (+3 more)
One of the central challenges in evolutionary dynamics is understanding why some species combinations persist while others disappear. Although cyclic-interaction models have provided fundamental insights into biodiversity maintenance, much less is known about how hierarchical competitive interactions shape long-term community organization. Here, we investigate a hierarchical extension of the May-Leonard model, in which species interact through a directed predation chain while undergoing reproduction and mortality. Combining mean-field analysis with Monte Carlo simulations, we show that the fully coexisting state is generically unstable, causing the dynamics to evolve toward lower-dimensional coexistence states. The simulations further reveal
stochastic extinctions dominating small populations with the dynamics progressively approaching the mean-field predictions as the system size increases. Rather than permitting arbitrary species combinations, the hierarchical-interaction structure dynamically constrains coexistence by selecting only specific subsets of species for long-term persistence. We show that these admissible coexistence states have a natural graph-theoretic interpretation as independent sets in the hierarchical interaction network, thereby providing general constraints on coexistence in hierarchical communities. Together, these results establish a theoretical framework linking hierarchical interactions, dynamical selection, graph
topology, and biodiversity organization, extending the classical May-Leonard model beyond cyclic competition.
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All authors Rakesh Samanta, Shraosi Dawn, Sk Jahiruddin, Sirshendu Bhattacharyya, Chittaranjan Hens, Sayantan Nag Chowdhury
Solar and Stellar Astrophysics
Open Clusters as Laboratories for Cool Star Evolution: Highlights from the Cool Stars 23 Splinter Session
Deepak Chahal, Beatrice Caccherano, Edward Gillen et al. (+16 more)
Open clusters remain among the most powerful laboratories for calibrating how fundamental
stellar properties such as rotation,
magnetic activity, surface chemistry, and internal structure evolve over the pre-main-sequence to main-sequence and post-main-sequence
stellar lifetime. Because cluster members share a common age,
galactic environment, and initial composition, they provide empirical anchors upon which age-dating techniques such as gyrochronology, activity-age relations, and chemical clocks are built. This paper summarizes the Cool
Stars 23 splinter session - Open Clusters as Laboratories for Cool
Star Evolution, held on 15 June 2026 in Tokyo, Japan. The session comprised one invited review, ten contributed talks, and ten poster pop-up presentations, organized around three themes: the
evolution of rotation,
magnetic activity, and chemical abundances (Li-depletion, [C/N], [Y/Mg], and
neutron-capture elements). We close with a summary of the open questions identified in the panel discussion and the observational and theoretical work that new surveys (e.g.
Gaia DR4, 4MOST, WEAVE) and missions (e.g. PLATO, Roman) will enable over the coming years. Together, these efforts will help assess the current state of the field and shape its future directions.
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All authors Deepak Chahal, Beatrice Caccherano, Edward Gillen, Dario J. Fritzewski, Robin D. Jeffries, Kevin R. Covey, Andrew Boyle, Lyra Cao, Federica Chiti, Alexander Hughes, Leslie Moranta, Natalie R. Myers, Emily K. Pass, Phil Van-Lane, Fábio C. Wanderley, Mackenna L. Wood, Stephanie T. Douglas, David Montes, Loredana Prisinzano
Fluid Dynamics
Fish navigate a hydrodynamic maze via yaw-mediated lateral migration
Michael A. Calicchia and Rui Ni
In aquatic environments, gradients in flow velocity and
turbulence define a constantly shifting landscape that sets the physical constraints on propulsion and energy expenditure in fish. Successfully navigating these complex flows depends on the ability to sense and respond to subtle hydrodynamic cues in an energy-efficient manner. Revealing these mechanisms is central to understanding how fish identify and exploit favorable flow conditions. To this end, we designed a hydrodynamic maze with spatially varying mean flow and
turbulence, creating a controlled heterogeneous flow landscape for understanding fish movement strategies. We found that fish escape energetically unfavorable regions by yawing their bodies relative to the flow. These yawed orientations appear to facilitate lateral migration through lift forces and may improve sensitivity to local flow variations. Notably, fish maintain body orientations near, but below, predicted stall conditions to exploit lift without a significant increase in drag. These findings provide insight into how fish navigate heterogeneous hydrodynamic environments, with potential relevance for both natural and engineered flow systems.
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Quantum Physics
Modular commutator as a robust topological invariant and approximate Markovianity
Tai Hsuan Yang
The modular commutator provides a bulk, local, single-wave-function probe of the
chiral central charge $c_-$ for gapped ground states. Its invariance under deformations was previously established under a local
quantum Markov condition—namely, the conditional mutual information $I(A:C|B)$ is zero for all tripartitions of a disk into three consecutive strips A, B, and C \cite{Modular-commutator-Gapped}. However, the local
quantum Markov condition also forces the probe to vanish, leaving open whether modular commutator remains robust in physically relevant states where the Markov property holds only approximately. In this paper, we resolve this tension for finite-dimensional
Hilbert spaces: the approximate local
quantum Markov property implies the change of the modular commutator under
topology-preserving deformations vanishes asymptotically. We next prove trace-norm continuity of the modular commutator. Combining deformation invariance with trace-norm continuity, we establish that the modular commutator remains asymptotically invariant within gapped
quantum phases connected by quasi-local
unitary paths that preserve the approximate local
quantum Markov condition. Conversely, by analyzing finite-time dynamics generated by modular
Hamiltonians, we derive a quantitative lower bound on the conditional mutual information required for a non-zero modular commutator: $I(A:C|B)$ across such strip tripartitions cannot decay faster than exponentially with the width of B given that the state satisfies
entanglement area law, extending the exact no-go
theorem of \cite{strict-J-2024} to a quantitative finite bound . Finally, we demonstrate that those conclusions apply equally to the
Hall conductance
estimator \cite{FanSahayVishwanath2023}.
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Mesoscale and Nanoscale Physics
Hilbert space connectivity in non-Hermitian many-body systems: emergent scale-dependent amplification and constraint-induced skin localization
Zichang Hao, Wen-Tan Xue and Ching Hua Lee
Various exotic many-body phenomena such as
quantum scars and fractons have been linked to
Hilbert space fragmentation. In this work, we find that in non-Hermitian settings,
Hilbert space connectivity has an even more universal and fundamental influence, tightly controlling the nature of spectral amplification and state localization. Far more complicated than real-space
lattices, non-Hermitian many-body
Hilbert space graphs not only possess intricate competing amplification channels, but also global feedback loops connecting remote Fock states related by particle
symmetry. These features lead to amplification behavior with unconventional scaling and localization properties. Particle occupation constraints can furthermore remove selected
Hilbert space pathways, leading to robust unipolar and asymmetric bipolar skin localization in otherwise reciprocal processes. These results extend beyond simple interacting bosonic models and establish
Hilbert space connectivity as a versatile control knob for many-body non-Hermitian critical transitions.
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High Energy Physics (Phenomenology)
Endothermic dark matter with a light dark photon and the LUX-ZEPLIN high-energy nuclear-recoil candidate
Pengxuan Zhu, Giovani Dalla Valle Garcia, Xuan-Gong Wang et al. (+2 more)
The LUX-ZEPLIN (LZ) experiment has reported an inelastic
nuclear-
recoil candidate at $E_{\rm nr}=248\pm23_{\rm stat}\pm23_{\rm sys}\,{\rm keV}$. We test whether endothermic pseudo-Dirac dark matter coupled to a kinetically mixed dark
photon can account for this event while reproducing the observed relic abundance. A five-parameter fit using an energy-only LZ likelihood and a relic-density likelihood favors TeV-scale dark matter with a mass splitting of a few hundred keV, and a GeV-scale mediator. The
recoil energy places the splitting near its kinematic ceiling, while secluded annihilation fixes the dark gauge coupling to a good approximation as a function of the dark-matter mass. Representative points predict $\mathcal{O}(1)$ accepted LZ event candidate and the observed DM relic density. Because the preferred splitting lies below the $e^+e^-$ threshold, the viability of the minimal model depends on the late-time excited-state abundance; a transition dipole can provide additional depletion, and the required light mediator remains testable in accelerator searches.
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All authors Pengxuan Zhu, Giovani Dalla Valle Garcia, Xuan-Gong Wang, Anthony W. Thomas, Martin J. White
Quantum Physics
Preparation of a Bell state in an analogue device hosting the transverse-field Ising model
Ana Palacios
We propose a protocol for preparing the singlet Bell state in an analogue device implementing the transverse-field Ising model with ZZ interactions and local X and Z fields, which can be engineered within the superconducting platform, among others. This protocol is performed by direct control of the terms of the
Hamiltonian alone. The method exploits the fact that the singlet state is the first excited state of a symmetric
Hamiltonian family, and comprises two steps: an adiabatic interpolation preparing the ground state of said symmetric
Hamiltonian, followed by the resonant population transfer between its two lowest energy levels. For realistic parameters, the protocol achieves fidelities comparable to standard gate-based preparation within similar time scales ($\sim$100 ns), and can reach infidelities on the order of $10^{-4}$ with a moderately increased duration. We further analyse robustness against systematic control errors and show that high fidelities are maintained under implementation imperfections.
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Astrophysics of Galaxies
Closed-Form of the Local Galactic Potential and Stellar Distribution Function from Gaia DR3
Indranil Das, Adam Kamoski, Dora Demiri et al. (+3 more)
The local dark matter density determines the strength of the signal expected in direct-detection experiments, yet published estimates from
stellar motions disagree by more than their errors, and the most recent machine-learning analysis of
Gaia data finds a local density consistent with zero. According to Jeans'
theorem, a distribution function built from integrals of motion satisfies the collisionless Boltzmann equation (CBE) trivially for any choice of potential, so a search that simultaneously fits the distribution function and the potential to the CBE identifies neither. Our pipeline instead estimates the distribution function in isolation, linearizing the equation in terms of accelerations and allowing for direct measurement of the local force field, and then fits closed forms to that field via symbolic regression. Throughout, we find that the usable information lies not in the CBE residual but in the
stellar number counts, the observable most distorted by survey selection. Along the vertical profile, our recovered potential agrees with the classical self-gravitating isothermal disc.
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All authors Indranil Das, Adam Kamoski, Dora Demiri, Brianna Isola, Hanieh Karimi, Dmitrii S. Zagorulia
Earth and Planetary Astrophysics
Combined JWST and HST Deep Imaging to Characterize the Smallest Known Trans-Neptunian Objects
Anastasia N. Morgan, Marielle R. Eduardo, David E. Trilling et al. (+9 more)
We present optical-near-infrared (NIR) color measurements for small ($\leq 40$ km) Trans-Neptunian Objects (TNOs) using coordinated and nearly simultaneous observations from the James Webb Space
Telescope (JWST) and the Hubble Space
Telescope (HST). JWST/NIRCam data provided detections and NIR photometry for faint TNOs, while HST/ACS and WFC3 imaging enabled recovery in the optical, together yielding optical-NIR colors spanning 0.35-3.2 $\mu$m. Thirteen JWST-detected TNOs were recovered in the HST observations, and trailed PSF photometry was used to derive mean magnitudes, colors, and rotational lightcurves. The color distribution of our small cold classical TNO discoveries is narrow and consistent with the occupation of a single reflectance (color) sequence previously identified for larger cold classical TNOs. We find no evidence for a change in this sequence at smaller sizes. In contrast, the dynamically excited TNOs we discovered exhibit a broader range of colors consistent with multiple compositional classes seen at larger sizes. Lightcurve amplitudes were generally low for both dynamical groups in our sample. 2015 GK56, a previously known TNO in our field, displays a large-amplitude, structured lightcurve consistent with a contact binary. Our results indicate that the characteristic color distribution of TNOs extends to smaller sizes than previously studied, suggesting a
primordial origin rather than size-dependent collisional processing.
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All authors Anastasia N. Morgan, Marielle R. Eduardo, David E. Trilling, Wesley C. Fraser, John A. Stansberry, Gary M. Bernstein, Bryan Hilbert, Matthew J. Holman, William M. Grundy, Kevin J. Napier, Stephen C. Tegler, Cesar Fuentes
High Energy Physics (Theory)
5d SCFT fixtures
Michele Del Zotto and Andrea Sangiovanni
In the context of the atomic classification of 5d SCFTs building blocks with non-simply laced global
symmetries are lacking. In this work we fill this gap by introducing a new class of 5d UV fixed points (the 5d SCFT "fixtures"). Physically, 5d SCFTs fixtures are the result of a
Higgs branch RG flow, realized geometrically by M-theory on singular threefolds which we identify explicitly. In particular, this enables the construction of 5d conformal matter SCFTs with non-simply laced
flavor symmetry. Along the way, we discuss their circle reduction in relation to 4d theories of class-S type.
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Optics
Stimulated Brillouin Scattering in InGaP-on-Insulator Waveguides
Yuyang Xue, Lisa-Sophie Haerteis, Ryan L. Russell et al. (+8 more)
Stimulated Brillouin Scattering (SBS) is a nonlinear interaction between optical and acoustic waves in solids. First regarded as a parasitic process in optical fibers, it has gathered significant interest in microwave photonic applications such as optical signal processing and narrow linewidth
lasers. While many Brillouin system demonstrations have been done on photonic chips, they struggle to provide simultaneous high Brillouin gain and narrow linewidth in a scalable platform, capable of integration with established photonic integrated
circuits. Here, we present a novel integrated InGaP-on-SiO$_2$ platform, where a single crystalline InGaP waveguide layer offers superior material properties and strong nonlinearities to support SBS near 1550 nm wavelength. We demonstrate backward SBS with a measured high Brillouin gain coefficient of $588\, \mathrm{W}^{-1}\,\mathrm{m}^{-1}$ and a record narrow linewidth of 5.2 MHz at 9.346 GHz frequency shift. This work establishes a wafer-scale complementary metal-
oxide semiconductor compatible fabrication process, paving a scalable path for high gain and narrow linewidth Brillouin photonics with applications such as precision signal processing.
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All authors Yuyang Xue, Lisa-Sophie Haerteis, Ryan L. Russell, Choon Kong Lai, Benjamin J. Eggleton, Michael J. Steel, Glenn Solomon, Kevin L. Silverman, Moritz Merklein, Andreas Boes, Nima Nader
Atomic Physics
Simultaneous sub-Doppler laser cooling and optical trapping of bosonic $^{39}$K-$^{133}$Cs and $^{41}$K-$^{133}$Cs mixtures
Mateusz Bocheński, Jakub Dobosz, Koray Dinçer et al. (+2 more)
We report simultaneous sub-Doppler cooling and optical dipole trapping of $^{39}$K-Cs and $^{41}$K-Cs mixtures. Both mixtures are cooled to temperatures $\sim10$ $\mathrm{\mu}$K, achieving performance comparable to that obtained with each species individually. To the best of our knowledge, this constitutes the first realization of a
laser-cooled and optically trapped $^{41}$K-Cs mixture. For the $^{39}$K-Cs mixture, we additionally implement parallel
spin-resolved Feshbach spectroscopy enabled by Stern-Gerlach separation. For potassium isotopes, we implement sub-Doppler cooling with $D_1$-line gray molasses, while for cesium the entire cooling sequence is implemented using $D_2$ transitions. We
spin-polarize the atoms and confine Bose-Bose mixtures in a 1064 nm optical dipole trap. Using the resulting $^{39}$K-Cs samples, we observe 14 heteronuclear Feshbach loss features. Five agree with resonances reported previously, while nine have, to the best of our knowledge, not been observed experimentally before, including $p$-wave features and resonances in additional
spin channels. The shorter lifetime of the $^{41}$K-Cs mixture in the optical dipole trap currently hinders systematic Feshbach spectroscopy, which we therefore do not pursue in this work. To characterize this limitation quantitatively, we study the decay dynamics of $^{39}$K-Cs and $^{41}$K-Cs mixtures under comparable temperature and density conditions, revealing a substantially stronger nonexponential loss in the $^{41}$K-Cs mixture. The demonstrated preparation of ultracold $^{41}$K-Cs mixtures provides a starting point for Feshbach-resonance and photoassociation spectroscopy of this previously unexplored isotopologue. Such measurements are essential for identifying suitable pathways for magnetoassociation and coherent optical transfer, and ultimately for the production of ultracold ground-state $^{41}$KCs molecules.
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All authors Mateusz Bocheński, Jakub Dobosz, Koray Dinçer, Paweł Arciszewski, Mariusz Semczuk
Quantum Physics
No information transmission through quantum channels above capacity
Hao-Chung Cheng and Marco Tomamichel
We show that the capacity of a
quantum channel demarcates a phase transition: while reliable transmission below capacity is always possible, any attempt to transmit information above it fails catastrophically. Specifically, we prove exponential strong converse
theorems for unassisted
quantum and classical communication over arbitrary finite-dimensional memoryless
quantum channels. At rates beyond the respective capacity, the
entanglement-generation fidelity and the success probability for classical communication decay exponentially with the number of channel uses. This rules out transmission above capacity even when one tolerates arbitrarily large errors. Our proof follows the classical Arimoto strategy, augmented by a crucial new ingredient: integral representations of Rényi information measures that lead to asymptotic continuity bounds for Rényi capacities.
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High Energy Physics (Phenomenology)
Final-state effects on the transverse-momentum spectra of charged hadrons in $p+Pb$ and $Pb+Pb$ collisions at $\sqrt {s_{\rm{NN}}}~=~5.02$~TeV using the modified Tsallis distribution
Kapil Saraswat, Deependra Singh Rawat, Manoj Kumar Singh et al. (+3 more)
The ATLAS Collaboration has reported measurements of the transverse momentum ($p_{\rm{T}}$) spectra of charged
hadrons in
proton-
proton ($p+p$),
proton-lead ($p+Pb$), and lead-lead ($Pb+Pb$) collisions at a nucleon-nucleon center-of-mass energy of $\sqrt{s_{\rm{NN}}}~=$~5.02~TeV within the rapidity interval $-2.5<y<2.0$. In the present work, we investigate medium effects on charged-
hadron production in $p+Pb$ and $Pb+Pb$ collisions using a phenomenological modified Tsallis parametrization that accounts for transverse collective flow in the low-to-intermediate $p_{\rm{T}}$ region and medium-induced parton energy loss at high $p_{\rm{T}}$. The modified parametrization provides a consistent description of the measured spectra over the full investigated $p_{\rm{T}}$ range across different centrality classes. The extracted energy-loss exponent $\alpha$, which characterizes the energy dependence of parton energy loss, is found to lie in the range 0.59$-$0.73 for $p+Pb$ collisions and 0.32$-$0.59 for $Pb+Pb$ collisions. In addition, the extracted parameters exhibit a clear centrality dependence, reflecting enhanced collective effects in central collisions. These results provide quantitative insight into the interplay between transverse collective flow and medium-induced parton energy loss in charged-
hadron production at LHC energies.
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All authors Kapil Saraswat, Deependra Singh Rawat, Manoj Kumar Singh, Prashanta Kumar Khandai, Damini Singh, Venktesh Singh