High Energy Physics (Phenomenology)
Minimal spontaneous baryogenesis from flavor
Martin A. Mojahed and Alfredo Stanzione
In its minimal realization, the Froggatt-Nielsen (FN) mechanism addresses the Standard Model (SM)
flavor puzzle via the spontaneous breaking of a horizontal $U(1)_H$
symmetry. If $U(1)_H$ is global and broken before the end of inflation, it gives rise to a pseudo-Nambu-Goldstone
boson (
axion-like particle) with a homogeneous initial misalignment, whose subsequent coherent
evolution sources spontaneous $CPT$ violation in the SM sector. We show that in the presence of $B-L$-violating processes $-$ parametrized here model-independently via the dimension-five Weinberg operator responsible for light
neutrino masses $-$ the minimal FN setup can generate the
baryon asymmetry of the Universe (BAU), linking the origin of
flavor directly to the BAU and
neutrino masses. Solving a complete set of
evolution equations for SM asymmetries, we demonstrate that this mechanism can readily yield a
baryon asymmetry comparable to the observed value, or even exceeding it by several orders of magnitude. Accounting for baryonic isocurvature and
entropy dilution from
axion decays, we find that the observed BAU is successfully reproduced for
axion oscillation temperatures above $10^{11}$ GeV and
axion decay constants ranging from $10^{13\cdots 14}$ GeV to above $10^{17}$ GeV. Finally, while we focus on a global $U(1)_H$
symmetry and
axion motion from standard misalignment, our framework is readily extendable to other global horizontal
symmetries and arbitrary
axion motion.
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Solar and Stellar Astrophysics
Evidence for Enhanced Helium Enrichment from Asteroseismology
Miqaela K. Weller, Marc H. Pinsonneault, Jennifer A. Johnson et al. (+1 more)
The helium abundance of a
star has a dramatic effect on luminosity, internal structure, and evolutionary timescales, yet direct helium measurements are unavailable for most
stars. In this work, we infer
stellar helium abundances by comparing observed and predicted luminosities for a sample of subgiants with asteroseismic masses from the APOKASC sample and spectroscopic parameters from recent survey compilations.
Stellar luminosities are predicted using grids of theoretical
stellar evolution models and offsets are attributed to helium differences from the assumed model value. From this analysis, we see clear evidence of helium enrichment correlated with
metallicity, $\Delta Y/\Delta Z = 1.959 \pm 0.061$, with the dominant error source being systematic differences in
stellar fundamental parameters. Our inferred enrichment slope exceeds the value implied by a
solar-calibrated helium enrichment relation, suggesting that commonly adopted assumptions regarding helium enrichment may underestimate
stellar helium abundances at high
metallicity. We further show that adopting the revised enrichment law can alter predicted main-sequence lifetimes by up to $\sim$ 1 Gyr and, in some cases, modify
stellar structure through changes in convective core development. These results demonstrate that uncertainties in helium enrichment propagate directly into
stellar age determinations and highlight the importance of empirical helium constraints for
stellar evolution models.
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All authors Miqaela K. Weller, Marc H. Pinsonneault, Jennifer A. Johnson, Charles Shunyu Yao
Superconductivity
Pair density wave order from non-symmorphic momentum symmetry
Matteo Dürrnagel, C. Alexander Baum, Michael Klett et al. (+2 more)
We develop a class of microscopic
lattice models in which pair density wave order emerges in the asymptotically exact weak coupling limit. The underlying mechanism is due to non-symmorphic momentum
symmetry implied by the models' projective space group representation of electrons. Our mechanism suggests moiré systems and extended s-wave altermagnets as potential hosts for pair density wave order.
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All authors Matteo Dürrnagel, C. Alexander Baum, Michael Klett, Lennart Klebl, Ronny Thomale
Instrumentation and Methods for Astrophysics
The information content of optical intensity interferometry
Neal Dalal, Biwei Dai and Matthew K. Browning
Optical intensity interferometry (II) can in principle resolve structure on angular scales $\theta\sim \lambda/B$, but it measures only the squared visibility $|{\cal V}|^2$, discarding
Fourier phase. We quantify what information can actually be recovered from phase-less $|{\cal V}|^2$ measurements as a function of the aggregate signal-to-noise ratio and array configuration, using score-based
diffusion models as non-parametric image priors. We construct an image reconstruction pipeline, and validate it by reconstructing a variety of images, including GRMHD simulations of black hole
accretion disks and actual SDO/HMI continuum images of the Sun, from phase-less
Fourier amplitudes. Using simulated data, we map the reconstruction fidelity of Sun-like
stellar surfaces as a function of noise level, number of $(u,v)$ samples, and maximum baseline $B_{\rm max}$, for surface maps spanning a range of activity levels. We find that fidelity depends on the data only through the total signal to noise ratio (SNR) of the surface features of interest, provided that the $(u,v)$ plane is sampled sufficiently densely. These results show that the SNR levels achieved by next-generation intensity interferometers observing realistic sources are sufficient to image highly complicated
stellar surfaces.
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General Relativity and Quantum Cosmology
A compact time-frequency representation for gravitational-wave data analysis
Noah Pearson, Mesut Çal{\i}şkan, Sophie Bini et al. (+1 more)
Time-frequency (wavelet) domain analyses are seeing greater use for gravitational-wave data analysis due to the advantages they have in handling non-stationary noise. A popular choice is the Wilson-Daubechies-Meyer (WDM) wavelet transform, which uses a window function that is very compact in frequency, but more spread out in time. In this work, we consider an alternative window function that is built from a sum of phase-shifted Gaussians. This "Gaussian" window is more symmetric in time-frequency, and consequently more compact. We examine the properties of this window function and the implications it has for gravitational-wave analyses. We calculate the window's time-frequency variance product analytically and verify it numerically. For the symmetric case, where the window has the same form in time and frequency, the construction comes within $\sim2.4\%$ of saturating the Heisenberg-Gabor uncertainty limit. We
conjecture that this Gaussian window achieves the minimum time-frequency area of any WD wavelet window.
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All authors Noah Pearson, Mesut Çal{\i}şkan, Sophie Bini, Neil J. Cornish
Astrophysics of Galaxies
Baryon-Accelerated Core Collapse in SIDM Halos and its Imprint on Galactic Disks
Zeineb Mezghanni, Elliot Y. Davies, Adriana Dropulic et al. (+3 more)
The gravitational coupling between dark matter (DM)
halos and the baryonic structures they host is one of the most powerful windows into the particle nature of DM. Self-interacting dark matter (SIDM) presents a minimal, well-motivated extension to the dark sector with dramatic consequences for the structure of
galaxies and their
halos. However, the impact of
baryons on SIDM
halo evolution and the resulting
galactic structure has been underexplored in Milky Way (MW)-size
galaxies. In this paper, we demonstrate that the inclusion of a baryonic component in a MW-size
galaxy causes accelerated core collapse to begin within the MW's lifetime for a cross section as low as $\sigma/m = 1 \, \rm{cm}^2/\rm{g}$. We present a suite of $N$-body simulations of cold dark matter and SIDM MW-size
galaxies with and without a baryonic component for cross sections $\sigma/m =[1.0, 2.5, 5.0]$ cm$^2$/g. We find numerically, and semi-analytically, that the presence of a
stellar disk and bulge shortens the predicted core collapse timescales from the DM only simulations by a factor of $\sim 40$. Further, as the core collapse begins within the lifetime of the
galaxy, the subsequent density increase strengthens the mid-plane restoring force exerted on
stellar disk orbits, leading the disk to
flare. This work quantifies both directions of the
baryon–SIDM coupling:
baryons accelerate core collapse in MW-sized
halos, and the resulting
halo evolution reshapes the disk through thinning and flaring. Both processes open new observational windows into DM.
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All authors Zeineb Mezghanni, Elliot Y. Davies, Adriana Dropulic, Gonzalo Herrera, Abdelaziz Hussein, Lina Necib
Earth and Planetary Astrophysics
POSTELLAR: Posterior Stellar Spectrum Sampling - An Alternative to Approximate Stellar Spectra for Exoplanetary Analysis
Dhvani Doshi, Nicolas B. Cowan, Yashar Hezaveh et al. (+2 more)
We present a novel approach to perform posterior sampling of the underlying
stellar spectrum in high-resolution spectroscopic observations. Our method, postellar, coherently combines information from empirical observations and physics-based models, enabling more accurate spectral recovery while providing uncertainties that can be propagated into downstream analyses. This is accomplished by treating the intrinsic
stellar spectrum as a latent variable and performing posterior sampling under a Gaussian likelihood with an informative prior constructed using a score-based
diffusion model trained on PHOENIX
stellar models. We validate the framework on synthetic SPIRou radial velocity (RV) observations generated from the empirical spectra of Barnard's
Star and Proxima Centauri. Spectra inferred with postellar more accurately recover the ground truth than standard empirical templates. For medium signal-to-noise observations, postellar improves RV accuracy by up to a factor of three, while RVs derived from empirical templates tend to be biased. This method performs particularly well in low signal-to-noise and low-cadence regimes. The postellar framework is broadly applicable to other high-resolution spectroscopy science cases including
stellar abundance analyses and
exoplanet atmospheric characterization.
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All authors Dhvani Doshi, Nicolas B. Cowan, Yashar Hezaveh, Gabriel Missael Barco, Étienne Artigau
Quantum Physics
Matrix Product Belief Propagation
Gabriel Woolls, Shahin Jahanbani, Adarsh Pashikanti et al. (+3 more)
We introduce "
matrix product belief propagation" (MP-BP) as a controlled method for the approximate contraction of two-dimensional tensor networks and graphical models, which generically leads to a quadratic reduction of errors relative to existing methods: at similar computational effort, the number of accurate digits is asymptotically doubled. For infinite systems, MP-BP can be understood as a practical implementation of Baxter's corner-transfer-
matrix method; for reflection-symmetric networks, it further coincides with the boundary
matrix-product-state and corner-transfer-
matrix renormalization group
algorithms as conventionally implemented. In the limit of unit
matrix-product rank, MP-BP is equivalent to belief propagation, and more generally, can be understood as a generalization of BP in which the "messages" live on surfaces and are assumed to have a
matrix-product factorization. We further extend the quadratic improvement to the computation of expectation values, and numerically demonstrate the qualitatively improved convergence for a variety of classical and
quantum 2D tensor network problems.
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All authors Gabriel Woolls, Shahin Jahanbani, Adarsh Pashikanti, Matthew T. Fishman, Joseph Tindall, Michael P. Zaletel
Cosmology and Nongalactic Astrophysics
Exploring the dark sector through galaxy dynamics in clusters
Andrea Biviano, Lorenzo Pizzuti and Antonaldo Diaferio
Galaxy clusters are among the most powerful laboratories to probe fundamental physics, from the formation of
cosmic structures to the nature of dark matter, dark energy, and
gravity. Realizing their full potential requires accurate and unbiased determinations of their mass profiles, a longstanding challenge in cluster cosmology. In this context, the kinematics of member
galaxies in clusters has become a key tool to reconstruct the mass distribution and to investigate the dynamical properties of clusters. The advent of large spectroscopic
datasets has enabled the application of increasingly sophisticated models and robust techniques, which make kinematic analyses competitive with other probes of cluster dynamics. In this review, we provide a comprehensive overview of cluster kinematics, covering the main methods to infer dynamical masses and mass profiles, their physical assumptions, and the impact of systematics such as deviation from dynamical
equilibrium, triaxiality, and substructures. We discuss the complementarity with other techniques to investigate the structure of clusters and highlight recent applications to tests cosmological models. We focus in particular on the role of kinematical studies in constraining the dark sector (dark matter and dark energy) and in providing novel insights into the behavior of
gravity at Mpc scales. Finally, we outline current limitations and future prospects, emphasizing that the combination of improved modeling and forthcoming spectroscopic surveys will establish cluster kinematics as a fundamental probe in the era of precision cosmology.
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General Relativity and Quantum Cosmology
End state of the experimental black-hole bomb
Patrik Švančara, Leonardo Solidoro, Pietro Smaniotto et al. (+10 more)
Rotating black holes can amplify incident waves through superradiant scattering. When these waves are confined, repeated amplification gives rise to the black-hole bomb instability, whose nonlinear
evolution remains poorly understood despite its central role in models of bosonic clouds around astrophysical black holes. Here, we reproduce the black-hole bomb mechanism in a laboratory setting using a
gravity simulator based on a draining
vortex in superfluid helium. Surface waves propagating on the superfluid interface experience an effective rotating spacetime and undergo repeated superradiant amplification within a cylindrical cavity. By tuning the temperature and flow parameters, we achieve exponential growth of a low-frequency resonant mode, followed by the arrest of the instability and the formation of a long-lived non-
equilibrium steady state. Using spatially and temporally resolved measurements, we identify nonlinear frequency shifts, harmonic generation, and coherent three- and four-wave mixing that redistribute energy among interacting modes. This novel end state of the experimental black-hole bomb highlights the role of nonlinear wave interactions in quenching the runaway growth expected from linear theory and governing the system's late-time dynamics. Our results establish a laboratory framework for investigating the nonlinear
evolution of black-hole bombs, with implications for analogous phenomena involving ultralight bosonic fields around rotating black holes.
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All authors Patrik Švančara, Leonardo Solidoro, Pietro Smaniotto, Sam Patrick, Silvia Schiattarella, Maciej T. Jarema, Sean M. D. Gregory, Vitor S. Barroso, Maurício Richartz, Anastasios Avgoustidis, Carlo F. Barenghi, Ruth Gregory, Silke Weinfurtner
Physics and Society
WolfSociety: Understanding Collective Risk from Harmful-Agent Scaling in Financial Agent Societies
Lejun Zhang, Sarah Lu-Liang, Xin Jiang et al. (+3 more)
Safety evaluations typically focus on individual
agents, but interacting
agents can spread harmful information and influence the environment in which later decisions are made. We study how collective failure changes with harmful-
agent fraction and society size in a controlled financial
agent society, where
agents communicate over a social network and trade in a shared
market. In the primary financial scenario, collective failure requires broad harmful
diffusion together with severe price dislocation or liquidity stress. Across all tested society sizes, failure remains rare at low harmful fractions but rises sharply over a narrow range. As society size grows from N=100 to N=2000, the harmful fraction associated with a 50% failure probability decreases from 4.7% to 2.2%, while the corresponding number of harmful
agents increases from approximately 5 to 44. In contrast, when the number of harmful
agents is held fixed, their impact becomes weaker as the society grows. Controlled interventions further show that broader network reach shifts the collapse boundary toward lower harmful fractions, whereas stronger conformity alone has little effect. To characterize these effects, we introduce
Agent Society Dynamics, a finite-size framework for relating harmful-
agent fraction, society size, and interaction structure to collective failure. Overall, our results reveal a nonlinear, size-dependent collapse transition in financial
agent societies, showing that collective failure depends not only on the prevalence of harmful
agents but also on the size and interaction structure of the surrounding society. Code is available at https://github.com/SAIL-Research-Lab/WolfSociety.
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All authors Lejun Zhang, Sarah Lu-Liang, Xin Jiang, Muning Wen, Weinan Zhang, Shangding Gu
Quantum Gases
Quantum Quenches across the Bose-glass Transition
Bo Song, Shaurya Bhave, Emmanuel Gottlob et al. (+2 more)
Due to their intrinsic interplay between long-range order and quasi-disorder, quasicrystalline systems provide a rich platform for investigating novel
quantum phenomena. Here we study the non-
equilibrium dynamics following
quantum quenches across the superfluid to Bose-glass transition using ultracold
bosons in an optical quasicrystal. Fast quenches into the Bose glass regime induce a
quantum walk in momentum space that spreads over increasingly higher momentum orders. Conversely, quenches into the superfluid regime initiate a real-space
quantum walk of initially localized atoms, forming a light-cone-like structure bounded by Lieb-Robinson limits. Characteristic timescales reveal strong links to the underlying
Hamiltonian and are governed primarily by quasi-disorder strength in the Bose glass phase, and by tunneling strength in the superfluid phase. Finally, we analyze slower quenches into deeper
lattices and observe the decay of coherence across the phase transition.
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All authors Bo Song, Shaurya Bhave, Emmanuel Gottlob, Leanne Reeve, Ulrich Schneider
Physics and Society
One equation allocates playing time in competitive team sports: the rulebook sets the arithmetic and the league sets the habit
Gustavo Pedro Ricou
Every team sport that lets a team replace players rations the replacements, and the ration settles who plays and for how long. Across eight codes, three in both sexes, we measure how playing time is allocated and find one equation behind it, complete in the one-way codes, its terms separating what the rulebook fixes from what a competition chooses. Under scarcity every league behaves alike: loaded starters are kept on at the same rate on four continents. Under freedom each expresses a preference, and the size of a league's departure is priced near one-for-one by what its own withdrawal minute prices (lambda = 0.87, 95% interval 0.54 to 1.21, twelve leagues), a law confirmed in four out-of-sample predictions and refused in one. The ordering of leagues by appetite persists across a rule change, and club wealth does not price it. Rules are the geometry of a competition; culture is its material.
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Mathematical Physics · Cross-listed from math.DG
Go Fishing with Alice: Compatible Carrollian and Poisson Structures
Andrew James Bruce
We introduce, motivated by noncommutative Carrollian geometry, the notion of a Carrollian–Poisson bundle understood as a Carrollian
manifold with a compatible Poisson structure. Compatibility is expressed as the inclusion of the Carroll distribution in the image of the Poisson anchor. We explore the
geometric consequences of this compatibility and present several simple examples of Carrollian–Poisson bundles, including the (outer) Kerr horizon, the BTZ horizon, and future null infinity. Furthermore, we establish that every Carrollian–Poisson bundle can be equipped with a Vaisman (contravariant) connection that is both metric-compatible and clock-compatible, and thus
geometric kinematics can be defined and studied.
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Instrumentation and Detectors
Nanoscale NMR of DNA-Functionalized Diamond Using Individual NV Centers
Erika Janitz, Konstantin Herb, Laura A. Völker et al. (+2 more)
Nuclear magnetic resonance (NMR) spectroscopy is a powerful probe of molecular structure and dynamics but typically requires large
spin ensembles. Here, we demonstrate nanoscale NMR detection of fluorinated DNA using individual near-surface nitrogen-vacancy (NV) centers in diamond nanopillar waveguides under ambient conditions. We covalently tether $^{19}$F-labeled oligonucleotides to mixed nitrogen- and oxygen-terminated surfaces, localizing target
spins within the nanoscale sensing volume. Probabilistic
spin simulations suggest that the measured signals are consistent with those expected from a few molecules and depend strongly on NV-molecule separation, configuration, and local surface heterogeneity. These results establish a framework for NMR of surface-tethered biomolecules and identify key challenges for single-molecule structural elucidation.
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All authors Erika Janitz, Konstantin Herb, Laura A. Völker, Christian L. Degen, John M. Abendroth
Earth and Planetary Astrophysics
Two extremely irradiated volatile-rich sub-Neptunes with companions in the TOI-426 and TOI-1839 systems: Insights into arrival and survival near the lower edge of the Neptunian desert
A. Castro-González, O. Barragán, D. J. Armstrong et al. (+26 more)
Using TESS photometry and 147 HARPS radial velocities, we confirm two extremely irradiated, volatile-rich sub-Neptunes near the lower edge of the Neptunian desert: TOI-426 b and TOI-1839 b, orbiting the
solar-type
stars HD 34390 and TYC 304-865-1. We modelled
stellar activity with shared-timescale and multidimensional Gaussian processes. The
planets have orbital periods of approximately 1.32 and 1.42 days, radii of $2.19\pm0.09$ and $2.27\pm0.10$ Earth radii, and masses of $6.7\pm1.8$ and $7.10\pm0.78$ Earth masses, respectively. They receive approximately 1700 and 1050 times Earth's irradiation, yet their densities require substantial volatile content. We also detect a transiting sub-Neptune, TOI-1839 c, at approximately 4.02 days and a
giant companion, TOI-426 c, with a period of $235.8^{+9.2}_{-8.5}$ days and a minimum mass of $444^{+18}_{-17}$ Earth masses, assuming a circular orbit. Interior-structure and atmospheric-escape models yield mass-loss timescales of 1-100 Myr for hydrogen/helium envelopes, compared with 100-1000 Gyr for water-dominated envelopes, favouring a steam-world interpretation for all three transiting
planets. A population analysis reveals a striking excess of detected outer
giant companions to low-mass sub-Neptunes near the desert edge, where high-eccentricity
tidal migration is expected to circularize surviving
planets: 36% (9/25) within the
tidal survival band versus 6% (9/148) outside it (Fisher exact test $p=1.4\times10^{-4}$). This excess is robust to changes in sample selection and companion definitions. The survival of these volatile-rich
planets challenges a boundary set solely by evaporation of
primordial hydrogen/helium envelopes, while the companion excess supports an important role for high-eccentricity
tidal migration in shaping the lower desert edge.
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All authors A. Castro-González, O. Barragán, D. J. Armstrong, A. Aguichine, V. Bourrier, D. Ehrenreich, E. X. Tao, J. Lillo-Box, M. R. Standing, S. G. Sousa, E. Delgado-Mena, A. Moya, V. Adibekyan, M. Lendl, C. Hellier, S. B. Howell, E. Furlan, C. Ziegler, A. C. M. Correia, K. Cui, P. Figueira, J. M. Jenkins, M. A. Fetzner Keniger, B. Merín, A. Osborn, L. Parc, F. Pepe, P. J. Wheatley, J. N. Winn
Cosmology and Nongalactic Astrophysics
Tracing the Cosmic Origins: Machine Learning Reconstruction of the Primordial Density Field from EoR Observations
Anchal Saxena, P. Daniel Meerburg, Guochao Sun et al. (+2 more)
Reconstructing the initial conditions of the Universe from late-time tracers would unlock cosmological information buried by non-linear structure formation and astrophysics. We reconstruct the initial density field corresponding to $z=300$, with its linear amplitude extrapolated to $z=0$, from simulated 21-cm and CO(1-0) line-intensity maps at $z=8$ generated with LIMFAST. Using a three-dimensional U-Net, we reconstruct the initial conditions and evaluate their impact on cosmological parameter constraints. The two tracers probe complementary environments: 21-cm emission traces neutral, low-density regions of the IGM, while CO traces overdense,
star-forming regions. We also train and evaluate the reconstruction on maps incorporating SKA1-Low- and COMAP-ERA-like instrumental response and thermal noise. In the noiseless case, combining both tracers delivers the most accurate reconstruction across ionisation states, with the cross-correlation coefficient between the reconstructed and true initial density fields, $|C(k)| \gtrsim 0.90$ for $k \lesssim 0.75\,{\rm Mpc}^{-1}$. With observational effects, small-scale information is degraded, but the joint reconstruction retains substantial large-scale coherence, with $|C(k)| \gtrsim 0.70$ for $k \lesssim 0.3\,{\rm Mpc}^{-1}$. We quantify cosmological information gains through simulation-based inference using power-spectrum summaries pre- and post-reconstruction. The largest improvements occur for $\sigma_8$ and $n_{\rm s}$, with a median aggregate marginal compression of $1.17$ bits in the noiseless case, corresponding to a $56\%$ reduction in the factorised product of prior-normalised $68\%$ marginal widths. With observational effects, the corresponding median compression is $1.29$ bits. These results demonstrate that joint 21-cm-CO reconstruction recovers cosmological information beyond pre-reconstruction summaries.
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All authors Anchal Saxena, P. Daniel Meerburg, Guochao Sun, Tzu-Ching Chang, Lluís Mas-Ribas
Cosmology and Nongalactic Astrophysics
Early against Late: A contrast on dark energy in the light of DESI DR2
Miguel A. Zapata, Karim Carrion and Gabriela Garcia-Arroyo
Recent findings from Dark Energy Spectroscopic Instrument (DESI)
Baryon Acoustic Oscillation (BAO) measurements, combined with Type Ia
supernovae and
Cosmic Microwave Background (CMB) data, suggest potential parameter-level deviations from $\Lambda\text{CDM}$. However, parameter exclusions omit prior-volume penalties, whereas
Bayesian evidence uncovers a stark dichotomy between early- and late-time dynamics. To quantify this effect, we perform a
Bayesian model comparison that explicitly accounts for the cosmological epoch of dark energy dynamics, contrasting two schemes acting in opposite epochs of
cosmic history: pre-recombination Early Dark Energy (EDE) and late-time Chevallier–Polarski–Linder (CPL), both measured against a baseline $\Lambda$CDM. We validate the learned harmonic-mean
estimator against UltraNest (at background level) before applying it to the CMB analysis. Background-only data already disfavor both extensions, yielding {$\ln B_{\Lambda\text{CDM},\text{EDE}} = 1.48 \pm 0.18$ and $\ln B_{\Lambda\text{CDM},\text{CPL}} = 2.36 \pm 0.24$}. Including CMB sharpens this result: {EDE is very strongly rejected ($\ln B_{\Lambda\text{CDM},\text{EDE}} \approx 12.61 \pm 0.17$)} with its early-time fraction constrained to $10^3\,\Omega_e^{\rm EDE} = 2.0^{+0.6}_{-1.0}$, whereas CPL remains only mildly disfavored ($\ln B_{\Lambda\text{CDM},\text{CPL}} \approx 2.34 \pm 0.18$), even though 2D parameter posteriors for both models display a multi-$\sigma$ deviation from $\Lambda\text{CDM}$. Thus,
Bayesian evidence weakens reported preferences for dark energy dynamics, with the impact depending on the
cosmic epoch involved, confirmed by our functional reconstructions of $w_{\rm de}(z)$ and $\Omega_{\rm de}(z)$ from posterior samples.
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High Energy Physics (Theory)
Decompactification and the Flat-Space Limit of AdS$_5\times$ S$^5$ Master Correlators
Burkhard Eden, Paul Heslop, Harshal Kulkarni et al. (+3 more)
We study the flat-space limit of AdS$_5$/CFT$_4$
holographic correlators while accounting for the simultaneous decompactification of the internal S$^5$. We show that this limit is naturally formulated in terms of master propagators and correlators, which resum the infinite tower of Kaluza–Klein modes. For boundary correlators, the resulting expressions can be interpreted in terms of amplitudes with kinematics restricted to 5d. We then consider master correlators whose external insertions are kept in the AdS$_5\times$S$^5$ bulk before taking the limit, and argue that they recover flat-space amplitudes with unrestricted kinematics in 10d Minkowski space. Finally, we show that the flat-space limit commutes with the boundary limit if we analytically continue the sphere so that the bulk geometry becomes AdS$_5 \times$dS$_5$, and the resulting formulae suggest an interpretation in terms of amplitudes in flat space with two time directions and with 10d kinematics satisfying two simultaneous null constraints. We discuss the implications of these constructions for flat-space holography and its relation to the Carrollian limit of the dual CFT.
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All authors Burkhard Eden, Paul Heslop, Harshal Kulkarni, Arthur Lipstein, Romain Ruzziconi, Akshay Yelleshpur Srikant
Quantum Physics
Towards Scaling Quantum Fine-Tuning of Foundational Time Series Models for Classification
Sang Hyub Kim, Julien Baglio, Rajiv Krishnakumar et al. (+7 more)
Time-series foundation models produce rich
embeddings, but whether
quantum models can exploit them, and how far hybrid classical-
quantum architectures scale, remains unclear. We address this by fine-tuning Chronos for power-grid event classification (PSML-5) with a
quantum head on the model's
embeddings. Grouping
embeddings by physical sensor type before summarization already surpasses the best published baseline built for this
benchmark, and with finer-grained features the
quantum head outperforms a larger classical multilayer perceptron on identical inputs by 1.7-2.0 percentage points of balanced accuracy. Yet the gains saturate: past a point, feeding more information to the same fixed-width register yields no improvement. We show the bottleneck is neither the supply of information nor
circuit expressiveness, but the bandwidth of the data intake. To overcome this limitation, we introduce the wing module, a self-contained few-
qubit circuit that feeds additional information into the core
circuit through a sparse, one-way coupling. Under a preregistered four-seed protocol, we attach wings to a fixed 12-
qubit core with fixed features. Balanced accuracy increases with each added wing, from 83.6% with no wings (13
qubits, including a post-selection
qubit) to 85.2% with two (19
qubits). Ablations establish that a
circuit enlarged without new information gains nothing, while a wing fed information from the wrong sample harms accuracy. These results reframe scaling for
quantum fine-tuning: added
qubits help when they carry added inputs, not merely more parameters. Wings offer a modular and stable route to widening that bandwidth.
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All authors Sang Hyub Kim, Julien Baglio, Rajiv Krishnakumar, Chi Chen, Oliver Knitter, Jonathan Mei, Claudio Girotto, Masako Yamada, Frederik F. Flöther, Martin Roetteler
General Relativity and Quantum Cosmology
Nonlinear evolution in Galileon EFTs: Regularization and screening
Farid Thaalba, Aaron Held, Ramiro Cayuso et al. (+1 more)
In a scalar effective field theory (EFT) with Galileon
symmetry, we distinguish the strong-field expansion from the derivative expansion and study spherically symmetric classical nonlinear dynamics. More concretely, we consider two models related via perturbative field redefinitions: one with second-order equations that can also exhibit screening, and one that includes a higher-derivative term that introduces a propagating ghost. The latter term is of the type that can “regularise” the equations to render them well-posed as an initial value problem. For initial data that respect the derivative expansion, we find that the first model (ghost-free, unregularised) develops ill-posed regions during
evolution only when the derivative expansion breaks down. This result persists in the strong-field regime. We further find that the regularized model reproduces the
evolution of the unregularised one when the latter remains well-posed, while it exhibits tachyonic behaviour when the unregularised one becomes ill-posed. We also consider initial data that corresponds to stationary states that exhibit screening in the unregularised, ghost-free theory. In this case, we find that the regularised theory can remain well-posed for initial data that the unregularised one developed ill-posed regions. However, the ghost term naturally dominates over the Galileon term in the screening regime, contrary to common expectation.
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All authors Farid Thaalba, Aaron Held, Ramiro Cayuso, Thomas P. Sotiriou
Quantum Physics
Squeezed light and coherent feedback enhanced multiparameter quantum estimation in a double-cavity optomechanics: steady and dynamical states
Hamza Harraf, Mohamed Amazioug, Amjad Sohail et al. (+2 more)
Multiparameter
quantum estimation in open optomechanical systems is fundamentally constrained by dissipation, thermal fluctuations, and measurement incompatibility. In this work, we investigate a coupled cavity optomechanical platform in which two mechanical modes interact with driven optical cavities, two mode squeezed
vacuum, intracavity degenerate parametric amplification, and coherent optical feedback. Using the continuous variable Gaussian state formalism, we derive the linearized
quantum Langevin dynamics and steady state covariance
matrix and evaluate the
quantum Fisher information
matrices associated with simultaneous estimation of the optomechanical coupling strength and cavity dissipation rate. We characterize the precision bounds using the symmetric and right logarithmic derivative formalisms and employ $\mathcal{B}_{\rm MI}=\max\{\mathcal{B}_S,\mathcal{B}_R\}$ as a comparative figure of merit within the SLD/RLD framework. We find that parametric amplification can substantially reduce the most informative bound, $\mathcal{B}_{\rm MI}$, thereby enhancing multiparameter estimation precision over a broad range of operating conditions. Coherent feedback can further reduce $\mathcal{B}_{\rm MI}$ and improve the estimation precision, particularly in the strong feedback regime. Moreover, the simultaneous presence of coherent feedback, parametric amplification, and squeezed light injection provides a combined mechanism for controlling
quantum fluctuations and parameter dependent correlations, leading to enhanced and more robust multiparameter estimation. We further analyze the dynamical and steady state regimes to identify the parameter regions in which these
quantum resources provide the largest metrological gain. Our results establish coupled cavity optomechanics as a flexible platform for
quantum-noise engineering in multiparameter sensing.
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All authors Hamza Harraf, Mohamed Amazioug, Amjad Sohail, Mojtaba Mazaheri, Rachid Ahl Laamara
Solar and Stellar Astrophysics
Metallicity dependence of Wolf-Rayet binaries using detailed binary models: An absence of long-period systems at low metallicity
Max M. Briel, Eirini Kasdagli, Tassos Fragos et al. (+6 more)
Observations of Wolf-Rayet (WR)
stars in binaries in the SMC and LMC suggest a preference for short period ($P\lesssim30$ days) orbits, with an apparent absence of WRs in long-period systems. The
Galactic population does extend to longer periods but shows a deficit in long-period WR binaries compared to their progenitors, the O-
star population. Across these populations a nearly constant binary fraction has been observed. We aim to characterize the population of WR binaries across a range of
metallicity and determine the
metallicity dependence of the formation of these systems, specifically focusing on the period distribution. We use detailed binary
evolution models from POSYDON to predict the population of WR binaries at 0.01, 0.1, 0.2, 0.45, and $1Z_\odot$, analyzing the resulting period distribution and formation channels, while comparing them against the observed population in the SMC, LMC, and Milky Way. We find that the absence of wider WR binaries in the SMC, and potentially in the LMC, can be explained by stable, Case-B mass transfer only partially stripping the donor
star, combined with WR winds at low
metallicity being insufficiently strong to strip the remaining envelope. As a result, the long-period peak from Case-B mass transfer, present at Zsun, disappears at low
metallicity. We additionally find that stable mass transfer (SMT) produces a short-period peak through Case-A mass transfer (P~5-10 days) that closely matches observations across
metallicity. Furthermore, SMT and non-interacting systems are the dominant formation channels of WR binaries at all
metallicities, with their relative contribution showing no
metallicity dependence. This result implies that the SMT channel has the same
metallicity-dependence as isolated WR formation. At the same time, we find that common envelope
evolution primarily produces short-period ($P<1$ day) WR binaries with black-hole companions.
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All authors Max M. Briel, Eirini Kasdagli, Tassos Fragos, Tomer Shenar, Jeff J. Andrews, Denzel Goh, Abhishek Chattaraj, Seth Gossage, Philipp Srivastava
Mesoscale and Nanoscale Physics
Variable Charge State, Magnetic Excitations, and Kondo Effect of Sm/g/Ir(111)
Shixuan Shan, Tamara de Ara, Lina Liu et al. (+7 more)
Using low-temperature scanning tunneling microscopy we investigate the charge state,
magnetic excitations, and Kondo features of individual Sm adatoms on
graphene/Ir(111). Depending on the number and distance of their neighbors, Sm atoms can be in two discrete charge states. At certain distances, a reversible transition between these two states is induced by the electric field of the STM tip leading to concentric charge rings in the images. Only atoms in one of the two charge states exhibit
magnetic excitations in d$I$/d$V$ spectra. Two such excitations are located at 35~meV and 54~meV and related to transitions from the $J = 1/2$ ground state doublet to the first
crystal field split $J = 3/2$ multiplet. Together with the intra-atomic exchange excitations at higher energy, these observations indicate that Sm transfers one $6s$ electron to the substrate while it retains its gas-phase $4f$ filling. New for lanthanide adatoms, we observe a Kondo resonance. The Zeeman splitting of the Kondo peak reveals that Sm retains its large gas-phase $g$-factor. Comparison of d$I$/d$V$ spectra to cotunneling theory yields the
crystal field acting on the $4f$ shell and, consequently, on the $J = 3/2$ quadruplet, confirms Sm$^+$ as the ground state, and identifies Sm$^{2+}$ as being energetically close, thereby rationalizing our observation of variable charge states.
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All authors Shixuan Shan, Tamara de Ara, Lina Liu, Zhipeng Wang, Marina Pivetta, François Patthey, Tadahiro Komeda, Daria Kývala, Jindřich Kolorenč, Harald Brune
Earth and Planetary Astrophysics
Ion abundances in the plasma tail of 3I/ATLAS show that it is N2-rich
Lea Ferellec, Cyrielle Opitom and Colin Snodgrass
Interstellar objects allow us to compare the early planetary formation process in the
Solar System and around other
stars. The second and third interstellar objects, 2I/Borisov and 3I/ATLAS, showed visible signs of activity, making it possible to assess their composition via spectroscopic analysis of their gas coma. While neutral volatiles surrounding comets are easily probed by common spectrographs, ion emissions emanate mostly from the tail, making them easier to detect with integral-field units. We present WHT/WEAVE-LIFU observations of 3I/ATLAS, performed post-perihelion on 2025 November 30 and 2025 December 02. We simultaneously detect the ions N2+, CO+, CO2+, H2O+ and CH+ located in an anti-
solar tail. Using common fluorescence factors, we determine abundance ratios of these species in the tail. In particular, the N2+/CO+ ratio allows us to constrain the lower-limit N2/CO>0.023+/-0.001, indicating that 3I/ATLAS is N2-rich compared to
Solar System comets, a property which can be linked to cold formation conditions. Abundance ratios between other ions cannot directly be used to constrain abundances of neutrals but seem consistent with the fact that 3I/ATLAS is enriched in hypervolatiles. We also investigate whether these ratios vary along the tail, and only detect a marginal decrease of CH+ with cometocentric distance.
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Materials Science
From Electronic Structure to Environmental Remediation: Adsorption of Ionized Glyphosate on COOH-Modified Carbon Nanotube
H. T. Silva, L. C. S. Faria, C. Aguiar et al. (+2 more)
Glyphosate is a widely used herbicide whose persistence and toxicity in aquatic and terrestrial environments demand efficient removal strategies. Here we employ GFN2 xTB calculations with implicit ALPB aqueous solvation and automated docking to investigate the adsorption of all five pH dependent ionized forms of glyphosate (G1-G5) on (10,0) single walled carbon nanotubes covalently functionalized with carboxyl groups at 0-25% coverage. Adsorption energies reveal a clear charge dependent trend: the dianionic (G4) and trianionic (G5) species exhibit the most negative binding energies over the entire functionalization range, while the protonated and neutral forms (G1, G2) bind weakly, approaching reversible adsorption at high COOH contents. The deprotonated form G5 strengthens from -2.17 eV on pristine CNT to about -5.7 eV at 10% and 25% functionalization, with a local minimum near 15-20% COOH due to steric and electrostatic crowding of adjacent groups. Decomposition of the solvation free energy shows dominant electrostatic stabilization complemented by increasingly favorable hydrogen bond contributions as carboxyl density grows. All complexes display very small HOMO-LUMO gaps (0.02-0.22 eV), indicating high electronic sensitivity to adsorption and functionalization. Overall, CNT+COOH systems can operate in both strong capture and regenerable regimes depending on glyphosate ionization state, offering a tunable platform for pH responsive remediation.
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All authors H. T. Silva, L. C. S. Faria, C. Aguiar, T. A. Aversi-Ferreira, I. Camps
Statistical Mechanics
Non-reciprocally interacting Ornstein-Uhlenbeck processes: Exceptional points, Anomalous relaxation, Pseudo-equilibrium and Boundary refrigeration
Soumya Kanti Pal and Shamik Gupta
Non-reciprocal interactions are ubiquitous in active, biological, and disordered systems, generically driving them out of
equilibrium. Here, we introduce a hierarchy of non-reciprocally interacting Ornstein-Uhlenbeck (NROU) models governed by a tunable non-reciprocity parameter $g$. At a special point $g=g^*$, the drift
matrix becomes non-diagonalizable, realizing exceptional points (EP's) of different orders, where
eigenvalues and eigenvectors simultaneously coalesce. The hierarchy encompasses non-reciprocally coupled dimers, their disordered counterparts, and a many-body chain exactly mapping onto the paradigmatic Hatano-Nelson model in the arena of non-Hermitian
quantum systems. For the disordered model, we show that the distribution of the EP location $g^*$ across disorder realizations develops a universal edge singularity precisely at the clean-system EP, and is manifestly non-self-averaging. Across all models, we find that at the EP, the usual exponential relaxation of the autocorrelation and covariance functions is dressed by a
polynomial-in-time prefactor whose degree is set by the order of the EP and whose detailed structure encodes the spatial architecture of the chain. At complete asymmetry, the many-body chain exhibits “pseudo-
equilibrium”: its steady-state distribution factorizes into
equilibrium-like single-particle measures despite a nonzero steady-state current. Moreover, the $N$-particle interacting system decomposes into $N/2$ independent complex OU processes. Finally, using the Harada-Sasa relation, we obtain a closed-form expression for the total steady-state heat dissipation and uncover a boundary refrigeration effect, in which the boundary particles switch from acting as a hot to a cold reservoir as the non-reciprocity is tuned.
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Quantum Physics
A photonic source with half-a-GHz single-photon flux
P. Zahalka, S. Huijser, A. Pancaldi et al. (+10 more)
Advanced optical
quantum technologies demands high quality
quantum light generation at very high rates. Here, we report on a deterministic single-
photon source that simultaneously combines high excitation rates with high system efficiency to reach over 500 MHz of in-fibre single-
photon flux. The source delivers optical power of over 100 pW, as is measured with an off-the-shelf powermeter, enabling a simple and direct way of determining the single-
photon source fiber efficiency.
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All authors P. Zahalka, S. Huijser, A. Pancaldi, S. Kruger, X. Zhao, Z. Liu, I. Suleiman, R. Jensen, L. Stefan, A. Ludwig, V. Remesh, J. C. Loredo, P. Lodahl
Materials Science
Anjali Panchwanee, Kai Schlage, Dieter Lott et al. (+8 more)
The advancement of spintronic nanoscale devices hinges on the ability to flexibly engineer
magnetic spin structures in thin-film stacks with precision and control. Meeting this demand remains a challenge for stable non-collinear
spin configurations and, more specifically, vertical
spin spirals in thin films. Innovative methods are required for their fabrication, stabilization and control. Here, we use oblique-incidence deposition to design and stabilize vertical
spin spirals at room temperature and without an external field in
magnetic thin films. We induce two crossed uniaxial
magnetic anisotropies at the thin film boundaries. These anisotropies are tunable in direction and strength, thus providing control over the angular range and depth profile of the resulting
spin spiral. The combination of polarized
neutron reflectometry and
nuclear resonant scattering enables precise and direct determination of the depth-dependent
spin configurations. Our results establish a single-film design approach, in which the surface anisotropies independently serve as controllable design parameters for tailoring the vertical
spin-spiral profile. Potential applications include nanoscale energy-storage devices,
magnetic sensors, and
ferromagnetic-resonance filters, advancing all-
spin-based device engineering in general.
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All authors Anjali Panchwanee, Kai Schlage, Dieter Lott, Sven Velten, Thomas Saerbeck, David L. Cortie, Sakshath Sadashivaiah, Ilya Sergeev, Guido Meier, Lars Bocklage, Ralf Röhlsberger
Quantum Physics
Coincidence-based spectral engineering for spectral matching in cascaded downconversion
Mohammed Charafi, Alexandre Z. Leger, Samridhi Gambhir et al. (+1 more)
Three-
photon states generated via cascaded spontaneous parametric downconversion provide a direct route to multipartite
entanglement. However, current implementations require careful spectral matching between successive nonlinear stages, which constrains the choice of downconversion sources. In this work, we show that coincidence-based spectral filtering relaxes this requirement by conditionally tailoring the spectrum of the pump
photon entering the second stage. By filtering the herald
photon, we conditionally tailor the spectrum of its partner to match the acceptance bandwidth of the secondary nonlinear process, enabling efficient coupling between broadband and narrowband stages without altering the sources themselves. Using an electro-optically gated spectrometer, we directly measure the conditional spectra that govern the cascaded process, allowing us to quantitatively predict the enhancement in second-stage conversion probability per detected herald. We then verify this prediction through
photon-triplet measurements, demonstrating improved performance at fixed heralding rates. Our results establish coincidence-based spectral engineering as a practical tool for optimizing cascaded downconversion, particularly in regimes limited by detector saturation or spectral incompatibility.
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All authors Mohammed Charafi, Alexandre Z. Leger, Samridhi Gambhir, Deny R. Hamel