High Energy Physics (Phenomenology)
Bottom-Charm $[bc]$ Diquark Masses from QCD Laplace Sum-Rules
T. de Oliveira, D. Harnett, J. Ho et al. (+5 more)
Constituent mass predictions for bottom-charm $[bc]$ color-antitriplet diquarks are generated using QCD Laplace sum rules. We calculate the diquark correlator within the operator product expansion to next-to-leading-order (NLO), including terms proportional to the four- and six-dimensional gluon and six-dimensional
quark condensates. Existing analytic expressions for the resulting multi-scale master integrals are insufficient for these calculations, so we utilize numerical $D$-dimensional loop integration techniques. The sum rule analyses stabilize in all four channels yielding constituent masses in GeV of: scalar ($0^+$) $(5.60\pm0.56)$, pseudoscalar ($0^-$) $(6.04\pm0.60)$, axial vector ($1^+$) $(5.60\pm0.56)$ and vector ($1^-$) $(5.99\pm0.60)$. These constituent mass results are discussed in comparison with values used in diquark models of tetraquark hadronic states. We also summarize QCD sum rule predictions for diquark masses for all possible
quark-flavor combinations, providing QCD-based criteria for assessing the diquark mass parameters used in constituent diquark models of
hadrons.
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All authors T. de Oliveira, D. Harnett, J. Ho, R.T. Kleiv, Siyuan Li, N. Loewen, A. Palameta, T.G. Steele
Quantum Physics
Quantum-classical algorithm interpolation for spatial search
Diogo Ramos and Duarte Magano
Quantum-walk
algorithms can quadratically reduce the dependence of spatial search on the classical hitting time $\mathrm{HT}$. Realising this speedup using standard
quantum-walk
algorithms, however, requires deep coherent
circuits, limiting their applicability on near-term and early fault-tolerant
quantum devices. We derive a parameterised family of hybrid
quantum-classical spatial search
algorithms that continuously interpolates between the classical and fully coherent
quantum regimes, trading off
circuit depth for total query complexity. For any $\gamma\in[0,1]$, our
algorithms use
circuits of depth $\widetilde{O}(\mathrm{HT}^{\gamma/2})$ and find a marked vertex with constant success probability at total cost $\widetilde{O}(\mathrm{HT}^{1-\gamma}\mathsf{S} + \mathrm{HT}^{1-\gamma/2}(\mathsf{U} + \mathsf{C}))$, where $\mathsf{S}$, $\mathsf{U}$, and $\mathsf{C}$ denote the setup, update, and checking costs, respectively. We also derive an optimal continuous depth-query trade-off for fixed-point amplitude amplification, providing a potential building block for other hybrid designs.
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Optics
High-resolution retinal matrix imaging via computational motion and aberration correction
Aymeric Melt, Léo Puyo, Victor Barolle et al. (+3 more)
High-resolution optical imaging of the human retina is essential for diagnosing ophthalmic and neurodegenerative diseases. While adaptive optics combined with coherence gating can resolve retinal structures at the cellular scale, it requires complex, costly, and cumbersome hardware to physically correct for ocular aberrations and motion.
Matrix imaging offers a powerful digital alternative by leveraging wave linearity to undo aberrations and multiple scattering; however, its in vivo deployment has been hindered by continuous, involuntary eye movements that destroy phase coherence during acquisition. Here, we overcome this fundamental barrier and demonstrate the first in vivo reflection
matrix imaging of the human retina using an ultra-simplified optical setup without physical correctors. We introduce a fully computational framework that tracks and compensates for multi-axial ocular motion directly from raw interferometric data, thereby restoring the phase coherence of a multi-spectral distortion
matrix. This enables local, high-order aberration correction to achieve diffraction-limited, volumetric imaging of retinal tissues. By shifting the hardware burden to physics-guided numerical computation, this paradigm opens the way for accessible, non-invasive, and high-resolution digital ophthalmology.
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All authors Aymeric Melt, Léo Puyo, Victor Barolle, Claude Boccara, Gereon Hüttmann, Alexandre Aubry
Solar and Stellar Astrophysics
Tracing Accretion and Inner-Disk Gas Evolution in the Orion Nebula via Br-alpha and CO
Konstantin V. Getman, Maria Claudia Ramirez-Tannus, Jenny Frediani et al. (+17 more)
We present a systematic spectroscopic study of hydrogen Brackett-alpha (Br-alpha) and carbon monoxide (CO) fundamental-band (4.3-5.2 micron) emission from a homogeneous sample of 0.2-1.5 Msun pre-main-sequence (PMS)
stars in the Orion Nebula observed with JWST/NIRSpec-MOS as part of our Chandra-JWST project. Using 73 Br-alpha and 46 CO spectra, we investigate correlations between warm-gas emission, stellar properties,
accretion, and environment with censored correlation and regression analyses accounting for multiple testing. Br-alpha luminosity correlates strongly with
accretion luminosity (Lacc), even after excluding sources within 2' of Theta1 Ori C, the nebula's main ionizing O-type
star, whose radiation may bias proplyd Lacc estimates. This supports Br-alpha as a robust empirical tracer of
accretion in PMS
stars. Br-alpha also correlates with visual extinction (Av) and more weakly with stellar bolometric luminosity and mass. CO fundamental-band luminosities likewise correlate positively with Lacc and Av, relationships that persist in a larger combined JWST/NIRSpec+MIRI sample spanning multiple
star-forming regions. In contrast to Br-alpha, CO luminosity shows no significant dependence on basic stellar properties, suggesting that warm molecular gas is governed primarily by
accretion and local disk conditions. The weaker correlations of the Spitzer/IRAC spectral slope with Lacc and Av suggest that warm inner-disk gas may evolve or disperse faster than optically thick dust. Overall, the CO results tentatively indicate declining warm-gas emission as disks evolve, modulated by
accretion-powered thermal and ultraviolet excitation, although variations in emitting area inherited from natal core conditions may also contribute.
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All authors Konstantin V. Getman, Maria Claudia Ramirez-Tannus, Jenny Frediani, Kevin L. Luhman, Eric D. Feigelson, Bayron Portilla-Revelo, Christian Rab, Valentin Brunn, Jan Forbrich, Thomas J. Haworth, Rens Waters, Arjan Bik, Charles J. Law, Andrew J. Winter, Vladimir S. Airapetian, Abygail R. Waggoner, Michael A. Kuhn, L. Ilsedore Cleeves, Sergio A. Dzib, Marco Padovani
Earth and Planetary Astrophysics
Paleo-heat flux estimates across Enceladus derived from flexural response of the ice shell
Chelsea Eakins, Francis Nimmo and Paul Schenk
Saturn's moon Enceladus has active plumes suggestive of locally high heat fluxes at present, and the present-day heating is reasonably well characterized. However, the moon's thermal history is not well understood. In this study, we model flexural deformation of chasmata and dorsae in various regions of Enceladus to find the effective elastic thickness of the ice shell and constrain temporal and spatial variations in heat flux. We find paleo-heat fluxes of 60-$\geq$350 mWm$^{-2}$, with most clustered around 125-200 mWm$^{-2}$. Present day measured heat fluxes at the South Polar Terrain (SPT) are comparable to our estimated paleo-heat fluxes in non-SPT regions. Our paleo-heat fluxes, however, are significantly higher than the corresponding present day heat fluxes for the same locations inferred from shell thickness maps. This suggests that regions outside the SPT experienced a past episode of heating (heat fluxes in excess of 100mWm$^{-2}$) followed by a cooling and thickening ice shell. A relatively constant paleo-heat flux for terrains of different ages (determined from crater densities) supports the "resonance locking" hypothesis of dissipation in Saturn and might imply a long-lived resonance between Enceladus and Dione. Our results suggest that Enceladus's tidal heating appears to have been consistent over time. Consistent peak heating at Enceladus could support a long-lived subsurface ocean, which has important consequences for astrobiology and the habitability of the outer solar system.
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Solar and Stellar Astrophysics
Chandra-JWST Probing the Effects of Moderate X-Ray Superflares on Protoplanetary Disks
Konstantin V. Getman, Kevin L. Luhman, Bayron Portilla-Revelo et al. (+17 more)
Powerful X-ray
flares from young
stars may rapidly alter the physical and chemical conditions of their
planet-forming disks, but direct observational tests remain scarce. We present a Chandra-JWST/NIRSpec study of infrared spectral variability associated with pre-main-sequence (PMS) X-ray
flares in the Orion Nebula. Combining six Chandra/ACIS-I observations with three NIRSpec-MOS visits, we analyze two-epoch spectra of 10 X-ray
Flare stars and 12 matched non-flaring Controls among 84 observed disk-bearing PMS
stars. We investigate three diagnostics: narrow 2.8-4.3 micron features, HI Br-alpha, and the CO fundamental band.
Flare stars show tentative evidence for relatively fewer variable narrow features at longer wavelengths than Controls, while feature incidence decreases strongly with projected distance from the dominant ionizing O
star Theta1 Ori C. Most classifiable features appear in absorption. These properties suggest that at least some features may arise in externally irradiated disk atmospheres and/or associated photoevaporative flows, with their apparent epoch-to-epoch variability potentially reflecting spatial sampling of such locally structured material rather than intrinsic temporal changes. Br-alpha behaves differently:
flare stars show systematically stronger variability and uniquely exhibit absorption-core profiles, suggesting control by magnetospheric
accretion and stellar
magnetic processes rather than disk irradiation. The CO fundamental band shows no significant
flare-associated variability, consistent with thermochemical models predicting weak responses to moderate X-ray superflares. This pilot study demonstrates the potential of coordinated Chandra-JWST observations to probe how young stellar
magnetic activity affects
planet-forming environments, motivating future monitoring to build larger superflare samples and extend them into the rare X-ray mega-
flare regime.
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All authors Konstantin V. Getman, Kevin L. Luhman, Bayron Portilla-Revelo, Christian Rab, Valentin Brunn, Eric D. Feigelson, Arjan Bik, Jan Forbrich, Jenny Frediani, Thomas J. Haworth, Charles J. Law, Marco Padovani, Maria Claudia Ramirez-Tannus, Andrew J. Winter, Vladimir S. Airapetian, L. Ilsedore Cleeves, Sergio A. Dzib, Michael A. Kuhn, Abygail R. Waggoner, Rens Waters
Mathematical Physics
On the Mathematical Structure of Helical Shear in Anelastic Continua
Souhayl Sadik, Giuseppe Saccomandi and Luigi Vergori
We study helical shear of a thick-walled tube made of an incompressible, isotropic hyper-anelastic solid carrying a radially symmetric distribution of axial screw dislocations. Through the Bilby–Kröner–Lee decomposition, the dislocations are encoded in a Weitzenböck material
manifold, whose Riemannian metric alone enters the elastic response.
Equilibrium reduces at each radius to an algebraic system for the azimuthal and axial shear strains, whose cross terms are proportional to the dislocation strength and to the dependence of the strain energy on the second invariant; the two shear modes therefore couple only in the presence of dislocations. Exact solutions are obtained for neo-Hookean, Fung–Demiray, Gent, Knowles, and Mooney–Rivlin materials, and numerical ones for Gent–Gent materials. The universal relations of Horgan and Saccomandi are extended to dislocated generalized neo-Hookean tubes. Dislocations stiffen the tube when the strain energy stiffens with the first invariant, couple the two shear modes chirally when it depends on the second, and may restrict admissibility: they cap the dislocation strength in Gent and Gent–Gent materials, and contract the admissible traction region in Knowles materials with power-law index below n = 1/2. A weakly nonlinear analysis to third order in the applied tractions and dislocation strength shows that, at first order (linear elasticity), the dislocations leave the shear response unaffected while carrying a residual stress. The chiral coupling enters at second order, through the dependence of the strain energy on the second invariant, so that every dislocated material couples the modes as the Mooney–Rivlin solid with the same second- and third-order moduli. At third order, no new coupling arises; the modes interact through stiffness corrections involving the fourth-order modulus, which the dislocations further correct mode by mode.
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Quantum Physics
Selective Control and Imaging of Higgs and Goldstone Modes with a Quantum Simulator
Connie Miao, Pranjal Praneel, Thomas G. Kiely et al. (+5 more)
We realize the mesoscopic Bose-Hubbard model at unit-filling on a two-dimensional array of transmon
qubits and selectively excite collective modes associated with amplitude or phase fluctuations of the superfluid order parameter. We identify these modes respectively as the
Higgs and Goldstone modes using complementary local observables, extracted from measuring the number of particles on each site. Modulation of the coupling between sites excites the
Higgs mode, which we detect via the density of doubly occupied sites. In contrast, modulation of the local chemical potential with an appropriately chosen spatial profile excites the lowest-frequency Goldstone mode, which we detect via changes in the local density. The two modes have different
symmetries and do not couple to one another. By varying the system geometry, we characterize the impact of finite system size on the
evolution of both modes. In the thermodynamic limit, decay into a continuum of lower-energy excitations can obscure the
Higgs response. In our mesoscopic system, however, the finite system size leads to spectral gaps and allows us to detect the
Higgs mode as a coherent, long-lived excitation. Our work demonstrates how finite
quantum simulators can isolate and probe physical phenomena that become difficult to resolve in the thermodynamic, large-scale limit.
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All authors Connie Miao, Pranjal Praneel, Thomas G. Kiely, Eliott Rosenberg, Nicole S. Ticea, Pedram Roushan, Erich Mueller, Andre G. Petukhov
Atmospheric and Oceanic Physics
Collaborative Neural Networks significantly Improve Global Aerosol Retrievals From Multi-Angle Polarimeters
Guangliang Fu, Sha Lu, Meng Gao et al. (+2 more)
We present the RemoTAP-Hybrid
algorithm for global aerosol products retrieved from Multi-Angle Polarimeters (MAP), and apply it to one-year aerosol
retrievals from the SPEXone MAP instrument. For the first time, Multiple Collaborated Neural Networks (MCNN) are used to perform global aerosol MAP
retrievals over land and ocean. The combined use of MCNN with a full physics inversion in RemoTAP-Hybrid, significantly improves accuracy and computational speed of SPEXone aerosol
retrievals. We validate the retrieved Aerosol Optical Depth (AOD), Angstrom Exponent (AE), Single Scattering Albedo (SSA), Absorption AOD (AAOD), Fine mode AOD (FAOD), Coarse mode AOD (CAOD), and fine mode effective radius (reff_fine) with AERONET data. The validation suggests that aerosol
retrievals can be further improved when extending the aerosol description to include a fine non-spherical mode. For AOD, the Root-Mean-Square Error (RMSE) is 0.051 (0.037) over land (ocean), while 78.3% (80.8%) of the
retrievals are within the requirement formulated by the Global
Climate Observing System (GCOS). The RMSE is 0.186 (0.207) for AE, 0.038 (0.044) for SSA, 0.023 (0.014) for AAOD, 0.047 (0.031) for FAOD, 0.043 (0.027) for CAOD, and 0.021 (0.026) for reff_fine over land (ocean). Compared to the current RemoTAP
algorithm, RemoTAP-Hybrid shows improved agreement with AERONET for AOD, AE, and FAOD over land and ocean while the number of valid
retrievals is increased by 4% (3%) over land (ocean) and the computational time is reduced by 43% (32%). Finally, we present the first global seasonal maps of aerosol optical and microphysical properties and chemical composition from SPEXone.
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All authors Guangliang Fu, Sha Lu, Meng Gao, Jeroen Rietjens, Otto Hasekamp
Chemical Physics
Dual-Resonator Organic Microcavities for Triplet-Triplet Annihilation Upconversion
Robert H. Gordon, Rachel C. Kilbride, Michael Hutton et al. (+2 more)
Solid-state triplet-triplet annihilation upconversion offers a compelling route to harvest sub-bandgap
photons to increase the efficiency of photovoltaics, but low sensitizer doping required to suppress non-radiative aggregation quenching severely restricts light absorption. Here, we present a dual-resonator planar silver microcavity housing a thermally co-evaporated rubrene:palladium phthalocyanine (PdPC) active layer designed to simultaneously enhance triplet-sensitizer absorption and out-couple upconverted emission. By aligning a dispersive cavity mode with the PdPC absorption peak at $32^\circ$, we achieve a 12-fold enhancement in absorptance at 665 nm. This absorption boost, combined with directional outcoupling through a second cavity mode, outweighs cavity-induced reabsorption losses to yield a 22-fold peak and 4.5-fold integrated enhancement in detected upconversion emission. Overall, this work highlights the potential of microcavity integration to substantially enhance solid-state upconversion performance across low-intensity optoelectronic applications.
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All authors Robert H. Gordon, Rachel C. Kilbride, Michael Hutton, Jenny Clark, Robert D. J. Oliver
Instrumentation and Methods for Astrophysics
Studying the Near-horizon Jet of M87 using Millimeter Balloon-borne VLBI stations
Felix M. Thiel, Dominic W. Pesce, Mayukh Bagchi et al. (+2 more)
In this paper we present synthetic Very Long Baseline Interferometry (VLBI) observations of M87 between a near-future configuration of the Event Horizon
Telescope (EHT) and one or multiple 2.5 m-class balloon-borne VLBI stations on a northern transatlantic flight trajectory launching from Kiruna, Sweden. These balloon-borne VLBI stations have the advantage of operating above 99.5% of the atmosphere and their motion allows for efficient sampling of the uv-plane. Assuming frequency phase transfer between 230 and 86 GHz we run these simulations using a modified version of the ngehtsim software package. Our simulations demonstrate the ability of such a VLBI array to probe M87 at the jet base adding baselines down to 0.2 G$\lambda$ for a single balloon-VLBI station and 0.07 G$\lambda$ for three balloon VLBI stations. Using the
Bayesian imaging software Comrade.jl, we demonstrate the recovery of jet structures up to 150 $\mu$as in size for a single balloon and up to 300 $\mu$as in size with three balloons. Finally, we test the improvement in jet image fidelity by computing the normalized cross-correlation (NXCOR) and normalized-root-mean-square error (NRMSE) between the image reconstruction and ground truth. We find a factor of 1.2 improvement in the jet NRMSE for a single balloon and a factor of 1.3 improvement for 3 balloons as compared to EHT-only simulations.
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All authors Felix M. Thiel, Dominic W. Pesce, Mayukh Bagchi, Laura M. Fissel, Lindy Blackburn
Computational Physics
Standardized Planck-Mean Absorption Coefficients for High-Temperature Gases
Ryan D. DeBoskey, Clayton M. Geipel and Brian T. Bojko
Planck-mean absorption coefficients of pure gases are calculated from line-by-line integrations of HITEMP and ExoMol spectra up to 5000 K for use in high-enthalpy radiative heat transfer simulations. The
dataset extends beyond conventional combustion products, including high-temperature radicals, nitrogen-bearing species, soot precursors, metal oxides, metal hydrides, and halides: AlF, AlH, AlO, BH, C2, C2H2, CH, CH4, CN, CO, CO2, H2O, HBO, HCN, HF, MgH, MgO, N2O, NO, NO2, OH, SiO, TiH, TiO. New calculations are validated against historical correlations for overlapping species, demonstrating good agreement over their applicable temperature ranges. Strong visible opacities result in large Planck-mean absorption coefficients for many of the considered species, highlighting the need to account for their radiative contribution in extreme environments. A brute-force search over several candidate functional forms is performed to provide a common set of coefficients, establishing a standardized framework that can be easily integrated into production solvers and extended as additional high-temperature line lists become available.
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Mathematical Physics
On optimal Wannier decay in dimension three
Simon Becker, Zhongkai Tao and Mengxuan Yang
For a Chern nontrivial Bloch bundle over the three
torus, we construct an orthonormal Wannier basis with the optimal pointwise decay $\mathcal{O}(|x|^{-5/2})$. All but one of the generators decay exponentially. This resolves the question left open in arXiv:2505.01999.
Exactly Solvable and Integrable Systems
Symmetries, Lax pair, and nilpotent Darboux transformation for the KdV-ghost system
A. Restuccia, J. Rosales-Gómez and A. Sotomayor
We analyze the KdV–ghost system arising from the BRST formulation of BF-type topological field theory, its
symmetries, Lax pair, spectral problem, zero-
curvature formulation and Darboux formalism. The system is invariant under shifts of the ghost field, whose generator does not commute with the BRST
symmetry of the KdV–ghost system. Their generators allow the introduction of a systematic procedure for generating new solutions from a given one, and the corresponding expressions in the Grassmann
algebra are obtained explicitly. We introduce a Grassmann-valued Lax pair and prove an isospectral
theorem relating the spectral problem of the spatial Lax operator for the KdV equation to that of its KdV–ghost extension. We also construct a triangular zero-
curvature representation and show that the Grassmann-valued spatial Lax operator is related to the KdV spatial Lax operator by a nilpotent conjugation. The natural variable for a local Darboux formulation is the differentiated ghost $v=C_x$, for which the ghost equation coincides with the Fréchet linearization of the KdV flow. We then construct a nilpotent lift of the scalar KdV Bäcklund–Darboux transformation. Using Riccati variables and off-shell factorization identities for the KdV residue and its Fréchet derivative, we prove that the transformation closes on the local KdV–ghost system. Successive Darboux transformations yield a recursive ghost extension of the bosonic Darboux chain, with a new odd homogeneous contribution introduced at each step. For the solitonic examples, the resulting local ghost fields are naturally identified with tangent directions associated with the
soliton phase parameters. The construction provides a Darboux-theoretic interpretation of the ghost sector while remaining distinct from the standard supersymmetric KdV hierarchies.
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Geophysics · Cross-listed from stat.ML
Structure-aware Bayesian full waveform inversion via diffusion-regularized Stein variational gradient descent
Chao Li, Mrinal K. Sen, Sergey Fomel et al. (+1 more)
Full waveform inversion (FWI) is a powerful tool for high-resolution subsurface model reconstruction, but it remains highly nonlinear and ill-posed, especially when the initial model is inaccurate or the acquired data are noisy and incomplete. Annealed Stein variational gradient descent (ASVGD) provides a particle-based
Bayesian framework for FWI by approximating the posterior distribution with an ensemble of velocity models, thereby enabling uncertainty quantification beyond a single deterministic solution. However, conventional ASVGD-FWI commonly relies on simple handcrafted priors, such as Gaussian or smoothing assumptions, which are often insufficient to represent complex geological structures. To address this limitation, we introduce a learned
diffusion model (DM) as an implicit regularization mechanism within the ASVGD-FWI framework. Instead of explicitly evaluating the
diffusion prior density, the trained
diffusion model acts as a learned geological projection operator that guides updated particles toward the distribution of plausible velocity models. In this way, the proposed method combines data consistency from FWI, posterior diversity from ASVGD, and structural realism from the
diffusion prior. Numerical experiments demonstrate that the
diffusion-regularized ASVGD-FWI produces more geologically consistent mean models, suppresses nonphysical artifacts, and yields uncertainty estimates that are more concentrated around structurally complex and poorly constrained regions. These results suggest that learned
diffusion priors can effectively enhance
Bayesian FWI by improving both inversion stability and the interpretability of posterior uncertainty.
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All authors Chao Li, Mrinal K. Sen, Sergey Fomel, Yangkang Chen
Astrophysics of Galaxies
Galactic Outflows and Star-Formation Quenching: A JWST Perspective
Rebecca L. Davies and Sirio Belli
Outflows driven by active galactic
nuclei (AGN) are widely considered a key mechanism for regulating and quenching
star formation in massive
galaxies. However, direct observational evidence linking outflows to quenching has remained elusive for decades. This article reviews recent findings for massive
galaxies at
cosmic noon ($z\sim 2$), based on sensitive James Webb Space
Telescope (JWST) observations tracing both
star formation histories (through Balmer absorption lines) and neutral outflows (through blueshifted NaID absorption). Neutral outflows are found in $\sim$ 25 - 50% of massive ($\log(M_*/M_\odot)>$ 10)
galaxies, independent of
star formation rate. Outflows from
star-forming
galaxies are consistent with being powered by
star-formation and/or AGN activity, whereas outflows from quiescent systems are generally attributed to current or previous AGN activity. There is growing evidence that recent rapid quenching of
star-formation is associated with powerful AGN-driven outflows with mass loading factors $\eta \gtrsim$ 1 - 10. The neutral gas dominates the outflow mass budget but in most cases its velocity is below the
halo escape velocity, indicating that this gas may form part of a galactic fountain. Detections of neutral gas inflows and residual cold gas reservoirs in quiescent
galaxies suggest that other feedback mechanisms such as AGN heating are required to keep
galaxies quenched over long timescales. We highlight the potential of multiphase outflow measurements to constrain feedback models, describe the main systematic uncertainties in mass outflow rate measurements, and discuss how the $z\sim 2$ results inform our understanding of the formation of the earliest massive quiescent
galaxies.
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Quantum Physics
Cavity-assisted dynamic nuclear polarisation
Tristan Lorriaux, Yutian Wen, Patrice Bertet et al. (+2 more)
Dynamic nuclear polarisation transfers polarisation from electron to nuclear
spins by relying on a dissipative channel. Here we introduce a cavity-based DNP mechanism which uses the radiative relaxation of the electronic
spin through the Purcell effect to bring about the nuclear
spin polarisation. We implement this protocol on an ensemble of bismuth donor
spins (I=9/2, S=1/2) in isotopically purified silicon coupled to a superconducting resonator. A single cycle, combining adiabatic microwave and
radio-frequency pulses with Purcell relaxation, increases a target ground state's population by a factor of $1.79\pm0.04$; a cumulative enhancement of $4.6\pm0.2$ is reached with additional cycles, to be compared with the theoretical limit of ninefold set by the degeneracy of the ground
manifold. We explain this difference by the competition between Purcell and intrinsic relaxation on the one hand and a collective effect that slows down the electronic
spin radiative decay as the nuclear
spin population grows on the other hand. Our results place radiative DNP as an available mechanism at millikelvin temperatures where
phonon-mediated relaxation is frozen.
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All authors Tristan Lorriaux, Yutian Wen, Patrice Bertet, Benjamin Huard, Audrey Bienfait
High Energy Physics (Theory)
One-Loop Renormalization of Spin-$1/2$ SOPHIES
I. Díaz-Saldanña, A. Gutiérrez-Rodríguez, Armando de la C. Rangel-Pantoja et al. (+1 more)
In this paper, three formulations of
spin-$1/2$ Second-Order Pseudo-Hermitian
quantum field theorIES (SOPHIES) are built from scratch from parity eigenstates. Pseudo-Hermiticity allows the unconstrained fields to satisfy either Fermi–Dirac or Bose–Einstein statistics, while self-conjugate Majorana-like fields are only compatible with Fermi–Dirac. The set of independent four dimension renormalizable self-interactions of the three theories are identified, and the one-loop renormalization of the unconstrained fermionic and bosonic theories coupled to an abelian gauge
boson and enhanced with a Pauli term and including self-interactions is studied, together with the one-loop renormalization of the only independent quartic self-interaction of self-conjugate fields. The analysis leads to a rich set of Renormalization Group Equations with deep connections to known theories, like the Dirac formalism and the Klein–Gordon scalar through the fixed points of the Pauli coupling.
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All authors I. Díaz-Saldanña, A. Gutiérrez-Rodríguez, Armando de la C. Rangel-Pantoja, Carlos A. Vaquera-Araujo
Mathematical Physics
A direct theory of strain-gradient special Cosserat rods via the principle of virtual work
R. S. Hallyburton and C. Rodriguez
Motivated by recent advances in the synthesis of effective one-dimensional mechanical metamaterials, we develop a direct theory of strain-gradient special Cosserat rods based on the principle of virtual work. The internal virtual work is formulated intrinsically in terms of variations of the classical Cosserat strains and their spatial derivatives, without requiring a three-dimensional parent material or a stored energy. Objectivity and insensitivity to rigid virtual displacements characterize the admissible internal-work density, while localization yields the dynamic field equations, higher-order contact interactions, natural boundary conditions, and balances of linear and angular momentum. For inextensible and unshearable rods, the constrained principle determines a unique multiplier functional, although its representation by reactive force and double-force fields possesses a gauge freedom absent from classical rod theory. We also formulate objective elastic, hyperelastic, and viscoelastic constitutive laws, extend transverse hemitropy, transverse isotropy, and flip
symmetry to strain-gradient rods, and derive invariant representations of symmetric stored energies. As an application, we study a planar inextensible cantilever under a compressive terminal force. We prove that the
eigenvalues of the linearized problem are simple and coincide precisely with the loads at which bifurcation from the straight state occurs. In addition, each bifurcation point generates a connected global branch of nonlinear
equilibria that is locally analytic near its origin.
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Materials Science
Symmetry-selected extreme shear compliance in a stable carbon monolayer
J. W. González, M. Pachecho and J. D. Correa
Solids that are stiff to most loads and extremely compliant to one are normally built, not found. That internal atomic relaxation lowers elastic constants is textbook; what has remained untested is whether it can be driven far enough to separate the elastic scales of a
crystal by an order of magnitude while leaving it mechanically stable. Density functional theory calculations of the complete in-plane elastic tensor of four non-hexagonal carbon monolayers sharing a square
lattice metric show that it can: their longitudinal stiffnesses agree to within a factor of two while their shear constants span more than a factor of fifty. Twin T-
graphene, previously reported as elastically isotropic from normal strains alone, is the extreme case, with $C_{66}=3.03$~N\,m$^{-1}$, nearly fifty times below
graphene, at an axial stiffness typical of semiconducting monolayers, and a soft Kelvin
eigenvalue a factor of $29$ below the others while the Born criteria hold.
Symmetry confines the strain-induced relaxation to the $B_{2g}$ sector, a counter-torsion of the carbon sublayers about the short mid-plane bonds that removes $96\%$ of the clamped-ion shear stiffness with almost no bond stretching and leaves the semiconducting gap intact. Transverse acoustic
phonons, finite-temperature dynamics, and large-deformation simulations show that the channel survives beyond the harmonic, zero-temperature limit. Because the selection rule is a point-group statement rather than a chemical one, it yields a screening criterion for other
crystals and other strain components.
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Astrophysics of Galaxies
Emergence of high-mass stars in complex fiber networks (EMERGE) VII. Multi-Tracer Column Density Synthesis
Alvaro Hacar, Andrea Socci, Mario Tafalla et al. (+1 more)
Obtaining accurate estimates of the gas column density $\mathrm{N(H_2)}$ is crucial to determine the physical conditions of the molecular gas in the Interstellar Medium. This paper introduces the "Multi-Tracer Column Density Synthesis" (MT-CDS) technique, a new empirical approach to derive high dynamic-range column density maps with interferometers such as ALMA. We have compared the integrated intensity maps of two density selective tracers, namely HNC (1-0) and $\mathrm{N_2H^+}$ (1-0), obtained with IRAM-30m with ancillary Herschel column density estimates in seven
star-forming regions in Orion and derived individual temperature-corrected conversion factors for each of these tracers. We applied these conversion factors obtained at low-resolution into similar high sensitivity ALMA observations to derive independent column density maps describing both the low $N_\mathrm{HNC}\mathrm{(H_2)}$ and high $N_\mathrm{N_2H^+}\mathrm{(H_2)}$ column density components at high spatial resolution (4.5"). We also combined these independent maps into estimates for the total gas column density gas $N_\mathrm{tot}\mathrm{(H_2)}$ sampling more than two orders of magnitude in column density between $\sim 10^{21.5}-10^{23.5}$ cm$^{-2}$. A comparison with independent ArTeMiS column density maps at intermediate resolution (8") shows typical deviations of $\lesssim$0.2 dex from our MT-CDS gas column density estimates. We obtained individual column density maps in five of our targets at $\sim$2000 au resolution in which ALMA observations were available, that is a factor of $\sim$5 better than originally calibrated. These results demonstrate the potential of this MT-CDS technique to retrieve accurate, high dynamic range $N\mathrm{(H_2)}$ total gas column density estimates at interferometric resolution combining multiple molecular line tracers.
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All authors Alvaro Hacar, Andrea Socci, Mario Tafalla, Francesca Bonanomi
High Energy Physics (Theory)
Infrared-Finite Positivity Bounds in 4D Gravity
Ziyu Dong
We formulate an S-
matrix bootstrap in an exactly flat half-space, where boundary reflection provides
geometric infrared control for four-dimensional
gravity. Under the channel positivity conditions, we obtain an infrared-finite positivity bound on local four-scalar Wilson coefficients that includes a finite gravitational correction of order $G_N$ and is derived from the full UV absorptive spectrum without specifying a UV theory, imposing a spectral ansatz, requiring weak coupling or expanding the spectrum perturbatively. At fixed dimensionless external state parameters, the coefficient of the leading gravitational correction is independent of the EFT scale and requires neither an arbitrary soft resolution scale nor a model-dependent UV scale. Gaussian wave-packet scattering localizes interactions within the flat region and directly probes bulk Wilson coefficients while exponentially suppressing sensitivity to the boundary. Long-range gravitons remain sensitive to the boundary and give a finite contribution. The smearing functional passes numerical positivity tests with general half-space absorptive kernels in both crossed channels. An explicit string example shows how boundary reflection suppresses the collective contribution of string resonances to the absorptive part of the amplitude, connecting infrared control of low-energy scattering to the UV spectrum of
quantum gravity in the same dispersion relation. The framework opens a route to infrared-finite constraints on effective interactions across particle physics and
gravity.
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Geophysics
Physics-based deep learning for non-stationary adaptive multiple suppression
Chao Li and Yangkang Chen
Surface-related multiple elimination (SRME) is an indispensable processing step in marine seismic exploration, comprising two main components: multiple prediction and adaptive subtraction. While the multiple prediction is theoretically data-driven and relies on the data itself, the adaptive subtraction step requires a fairly subjective manual control. Our approach introduces a purely data-driven and physics-based deep learning (PDL)
algorithm for improving the adaptive multiple subtraction to significantly enhanced performance. There are two main innovations in the proposed deep-learning (DL) multiple subtraction approaches: first, being data-driven and self-supervised, which removes the dependence on inflexible label preparation and model training processes; secondly, being governed by the adaptive matching filtering (AMF) equation to guide the training process. The DL module serves as a strong regression filter analogous to the traditionally known AMF. We segment a moderately sized seismic profile and an initial multiple model into a large number of patches using a patching scheme for self-contained training. The number of patches is controlled by the patch size and the shift size to enable a sufficient number of training samples required by mainstream DL platforms. The patching-based self-training and regression approach, PDL, is inherently a non-stationary matching approach that aims to obtain a globally optimal matching from the initial multiple models to the input full wavefield data through iterative patching-based training. It is also closely connected with the non-stationary regression approach, which was developed almost two decades ago. However, the PDL approach achieves even stronger regression performance due to the backpropagation-based optimization mechanism in DL, and has shown significantly improved multiple subtraction performance over a number of examples.
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Astrophysics of Galaxies
SQuIGGLE: Radio AGN Found Predominantly in Young, Gas-rich Post-starburst Galaxies at z ~ 0.7
Vincenzo R. D'Onofrio, Justin S. Spilker, Krista L. Smith et al. (+13 more)
The processes that rapidly quench massive
galaxies and maintain their quiescence remain poorly understood. Substantial molecular gas reservoirs can survive this shutdown in post-starburst
galaxies, raising the question of what prevents the remaining gas from efficiently forming
stars. We present deep, subarcsecond VLA 6 GHz observations of 52 massive SQuIGGLE post-starburst
galaxies at $z\sim0.7$ to test the prevalence and mechanical impact of
radio activity during the gas-rich post-burst phase. We detect 6 GHz continuum emission in 18/52
galaxies ($\approx$35%), spanning $\log(L_{1.4\,{\rm GHz}}/{\rm W\,Hz^{-1}})\simeq23.0$–$25.0$ and generally exceeding the contributions expected from ongoing
star formation and the fading starburst, favoring an AGN origin. Ancillary data at other wavelengths provide little evidence for a population of luminous, radiatively efficient AGN, suggesting that these sources are instead dominated by comparatively weak, mechanically powered
radio AGN.
Radio activity is strongly concentrated within the first $\sim$200 Myr post-burst and is predominantly associated with
galaxies retaining substantial gas reservoirs. Above a common
radio luminosity threshold, the
radio detection fraction is enhanced by a factor of $\approx$2.5 relative to the
radio AGN candidate fraction in mass- and
redshift-matched quiescent LEGA-C
galaxies, primarily due to lower power sources. For efficient jet–ISM coupling, the inferred mechanical power could supply the approximate energy required to unbind the molecular gas on timescales comparable to its observed decline. Together, these results identify a population of radiatively inefficient AGN hosted predominantly by young, gas-rich post-starburst
galaxies at $z\sim0.7$ and suggest that they may have a role in maintaining inefficient
star formation.
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All authors Vincenzo R. D'Onofrio, Justin S. Spilker, Krista L. Smith, Rachel Bezanson, Robert Feldmann, Alex J. Geiger, Andy D. Goulding, Jenny E. Greene, Mariska Kriek, Anika Kumar, Yuanze Luo, Desika Narayanan, David J. Setton, Katherine A. Suess, Margaret E. Verrico, Pengpei Zhu
Physics and Society
A Sociophysics Approach to Measuring Democracy in the Decision Making of a Group: Three Indices
Sudipto Roy
A group does not usually consult all its members before every decision. This paper develops a quantitative framework for measuring how widely members are consulted in decision making within a group. Two kinds of records are considered: the number of members consulted for each decision and the number of decisions in which each member is consulted. From these records, two participation indices are defined, and their equality is proved analytically. A third index measures the fraction of decisions for which at least a specified percentage of members are consulted. The distribution of consultation levels is described using a discrete maximum-
entropy model from statistical physics. Tail probabilities are used to obtain bounds for the main participation index. This study examines aggregate survey data from two groups. Their observed characteristics are broadly consistent with the patterns found across the full survey. Using binomial and Poisson calculations, the future probability that all members will be consulted for a decision is examined. Inequality in consultation among members is examined through Lorenz curves, the Gini coefficient and a normalised Shannon participation measure. The member-decision structure is represented as a bipartite network. Controlled simulations show that the same overall level of consultation can have different distributions among the members. The framework measures both the overall breadth of consultation and how consultation is distributed among the members. It therefore provides a quantitative sociophysical description of one measurable aspect of democracy in decision making within a group.
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Mesoscale and Nanoscale Physics
Pseudo-relativistic fermions and topological states in zinc-blende semiconductors and their heterostructures (Habilitation thesis)
Sergey S. Krishtopenko
Tracing my scientific path from many-body physics in
semiconductor nanostructures to topological
quantum matter, this Habilitation à diriger des recherches (HDR) memoir presents only part of my research since defending two PhD theses in Toulouse and Nizhny Novgorod in 2011. Focusing on pseudo-relativistic
fermions and topological states in zinc-blende
semiconductors and their
heterostructures, it highlights my independent research program: identifying physical problems, developing predictive theories, and initiating new directions with experimentalists. The first part addresses Kane
fermions in bulk HgCdTe: temperature-driven band inversion, domain-wall states, the collapse of Landau levels in crossed electric and
magnetic fields, and disorder-induced topological transitions. The second examines pressure-, temperature-, and disorder-driven phase transitions in single and double HgTe
quantum wells (QWs), including bilayer-
graphene-like semimetals and a two-dimensional higher-order topological
insulator (2D HOTI) phase beyond the minimal BHZ model. The third develops three-layer InAs/Ga(In)Sb QWs as a III-V platform for massless Dirac
fermions, large-gap
quantum spin Hall
insulators, 2D HOTI phases, and semimetals with quadratic band touching, and discusses InAs$_{x}$Sb$_{1-x}$/InAs$_{y}$Sb$_{1-y}$
heterostructures as a promising alternative. Several of these predictions are supported by experimental observations, including quantized helical edge transport up to 60 K and the unconventional
quantum Hall effect. Defended on March 25, 2026, at the University of Montpellier. Jury: Michel GOIRAN (chair and rapporteur, LNCMI-CNRS, Toulouse); Alexey KAVOKIN (rapporteur, Westlake University, Hangzhou); Robson FERREIRA (rapporteur, LPENS-CNRS, Paris); Alexei BARANOV (member, IES-CNRS, Montpellier); Benoit JOUAULT and Frédéric TEPPE (members, L2C-CNRS, Montpellier).
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High Energy Physics (Theory)
Kinetic Equations and Turbulence in Large $N$ Vector and SYK-like Models
Vladimir Rosenhaus and Daniel Schubring
We apply large $N$ expansion techniques to derive kinetic equations for strongly coupled, far-from-
equilibrium field theories with $O(N)$
symmetry. For large $N$ vector models, the quasi-classical approximation holds. Incorporating arbitrary momentum-dependent interactions, we show the dynamics obey the standard kinetic equation, with the scattering amplitude given by the retarded propagator of the auxiliary Hubbard-Stratonovich field. This has broad applications to systems like
spin wave and Langmuir ion-acoustic
turbulence. For large $N$ random coupling (SYK-like) models in $d$ dimensions, leading-order melon diagrams induce order-one propagator renormalization and finite spectral width. The corresponding kinetic equation, unlike those for standard weakly interacting systems, does not have a local-in-time collision integral. We find evidence for a stationary, scale-invariant infrared solution, revealing a potentially novel strong
turbulence scaling exponent.
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Astrophysics of Galaxies
Are Broad Mg II Galaxies Fading AGN?
Stephanie M. LaMassa, Michael Eracleous, Jessie Runnoe et al. (+2 more)
We analyzed a sample of 494
galaxies from the Sloan Digital Sky Survey (SDSS) I-IV that have unusual properties. They display broadened Mg II $\lambda$2798 line emission, as would be expected of Type 1 active galactic
nuclei (AGN). However, they have weak or absent broad Balmer lines though broadened Balmer lines often accompany broadened ultraviolet lines in Type 1 AGN spectra. We performed a spectral decomposition of these "broad Mg II
galaxies” to assess whether they can be considered fading AGN. The Balmer lines are more responsive to changes in the AGN continuum than the Mg II line. As the AGN power source fades, broad H$\beta$ and then H$\alpha$ will weaken and eventually disappear, leaving broad Mg II as a signpost of a more active past. In support of this interpretation, we found that broad Mg II
galaxies have weaker AGN luminosities and lower
accretion rates (parameterized by the Eddington ratio) than typical Type 1
quasars from SDSS. The Eddington ratio of broad Mg II
galaxies are similar to dim-state changing-look AGN, with an average value $\lesssim$1%, which is the threshold at which the inner region of a geometrically thin
accretion disk is thought to evaporate and be replaced by a geometrically thick radiatively inefficient
accretion flow in stellar-mass black holes. Broad Mg II
galaxies may represent the penultimate stage in a changing-look AGN sequence prior to the complete disappearance of all broad lines.
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All authors Stephanie M. LaMassa, Michael Eracleous, Jessie Runnoe, Benny Trakhtenbrot, Gisella de Rosa
High Energy Physics (Phenomenology)
Effective Fermion-Photon Vertex in a Rotating Relativistic Medium: Tree-Level Structure
Jorge David Castaño-Yepes, Alejandro Ayala, J. E. Martínez-Herrera et al. (+1 more)
We study the tree-level
fermion-
photon effective vertex for on-shell particles in a relativistic environment undergoing rigid rotation at zero temperature. The rotational background breaks translational invariance in the transverse plane and introduces a preferred direction, leading to a distinct decomposition of the vertex into longitudinal and transverse structures with respect to the rotation axis. Using
fermion and
photon modes constructed in the rotating frame, we derive the corresponding selection rules and show that the energy and the longitudinal component of the momentum are conserved, whereas no independent transverse momentum-conservation condition arises. Instead, the transverse dependence is governed by radial integrals involving three Bessel functions, whose support constrains the magnitudes of the transverse momentum projections. The vertex can be organized in a circular basis for the transverse components and a Cartesian basis along the rotation axis, and expressed in terms of six Dirac structures. Their coefficients define 24 form-factor components associated with the
photon-mode components, physical
photon states, and
spin-dependent structures induced by the rotating background. We also verify current conservation and gauge invariance of the resulting tree-level
matrix element under the boundary conditions considered. These results provide the tree-level structure of the
fermion-
photon interaction in rotating relativistic matter and establish the basis for the study of radiative corrections in vortical backgrounds.
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All authors Jorge David Castaño-Yepes, Alejandro Ayala, J. E. Martínez-Herrera, Enrique Muñoz
Chemical Physics · Cross-listed from cs.LG
PairIT: Autoregressive Transformers for Low-Data Molecule Optimization
Hannah Lawrence, Bodhi P. Vani, Ji Won Park et al. (+5 more)
Generating novel molecules with desired properties is a central challenge in drug discovery. Although foundational work focused on de novo generation, practical use cases require a more complex setting: conditioning on an initial seed molecule, optimizing multiple properties, and operating in data-sparse regimes. We introduce PairIT, a flexible training framework for autoregressive
transformers over SMILES sequences that enables seeded generation by learning from pairs of structurally similar molecules. By leveraging matched pairs, the model learns to generate local, chemically meaningful edits that improve a property of the seed molecule.
Prompt tokens extend this framework by specifying the target property, desired direction, and approximate magnitude of change. Multiple
prompt tokens can be concatenated to enable multi-property optimization at inference time. For properties where pair supervision alone is insufficient, reinforcement learning post-training can further improve optimization, providing a tunable trade-off between proximity to the seed and the optimization objective. PairIT naturally supports pretraining on a large
dataset and fine-tuning on a smaller
dataset, which is critical for performance in data-sparse regimes. Surprisingly, we observe diminishing returns to the scale of the pretraining
dataset. We demonstrate empirically on MoleculeNet and Therapeutics Data Commons
datasets that, with appropriate paired-data curation, a standard
transformer model of modest size (68M parameters) can achieve robust seeded molecular optimization in low-data regimes.
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All authors Hannah Lawrence, Bodhi P. Vani, Ji Won Park, Natasa Tagasovska, Samuel Don Stanton, Andrew Martin Watkins, Michael Maser, Ewa M. Nowara