High Energy Physics (Theory)
Asymptotic boundary structure of Lagrangian gauge theories
Ivan Dneprov, Maxim Grigoriev and Mikhail Markov
Given a local gauge theory on spacetime with boundary, it naturally defines another gauge theory which can be regarded as a theory of the boundary values. For Lagrangian theories, it comes equipped with the presymplectic structure which can be used to define one or another version of
Hamiltonian-like formulation of the initial model. This relation is especially manifest for AKSZ sigma models and more-generally gauge PDEs with compatible presymplectic structure in which case the boundary system is again a gauge PDE with presymplectic structure. In the context of (flat space) holography one is interested in boundaries at infinity, also known as asymptotic boundaries. The gauge PDE framework naturally extends to this setup, resulting in the notion of gauge PDE with asymptotic boundaries. Although this works perfectly well at the level of equations of motion, the extension to Lagrangian systems appears quite subtle because the presymplectic structure capturing the Lagrangian is divergent at the boundary. We show that any $Q$-cocycle in the bulk (and presymplectic structure in particular) determines a pair of compatible $Q$-cocycles of the boundary gauge PDE: the renormalized one of the same ghost-degree, and the anomaly cocycle of degree one lower. For the latter, the construction is somewhat analogous to the residue map known in the context of b-geometry. The general formalism is exemplified by scalar and Maxwell fields on AdS and Minkowski spaces. It turns out that in the AdS case the natural action determined by the anomaly presymplectic structure is precisely the one known as the
holographic Weyl anomaly in the AdS/CFT context while its null-infinity counterpart was known in a few very particular cases only.
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Chemical Physics
Geometric Algebra Meets Cartesian Tensors: Higher-Order Equivariance for Interatomic Potentials
Can Polat, Erchin Serpedin, Mustafa Kurban et al. (+1 more)
$\mathrm{Cl}(3,0)$ interatomic potentials, despite their algebraic elegance, predict force magnitudes accurately but force directions poorly. Across ten rMD17 molecules, every $L \leq 1$ baseline in our twelve-model study attains aggregate force-cosine similarity below $0.25$. The cause is structural. The
geometric product of two vectors in $\mathbb{R}^3$ realises only the $L=0$ and $L=1$ components of its irreducible representation content, leaving the symmetric-traceless rank-2 component absent from the per-edge bilinear that drives each message-passing layer. We address this with CliffordSTF, which couples the Clifford multivector to closed-form symmetric-traceless tensor tracks at ranks two and three through bilinear cross-track contractions, using a single learned bilinear and no Clebsch–Gordan tables, Wigner-$D$
matrices, or e3nn calls. On rMD17, CliffordSTF raises aggregate force-cosine similarity from $0.055$ (base Clifford) to $0.551$, an order-of-magnitude relative directional gain, alongside improved magnitude accuracy (force MAE $15.8\%$ lower; energy MAE $10.9\%$ lower). It outperforms all CG-free or body-ordered baselines in our study (all $\leq 0.17$). On catalysis
benchmarks, CliffordSTF achieves the best out-of-distribution S2EF energy MAE on OC22 in our experiments, and the best in-distribution energy MAE among $L \geq 2$ methods on OC22 IS2RE. An eleven-variant ablation shows the two tracks are complementary: neither alone matches the combined model.
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All authors Can Polat, Erchin Serpedin, Mustafa Kurban, Hasan Kurban
Cosmology and Nongalactic Astrophysics
Constraints on Dark Energy and Modified Gravity Models from Fast Radio Bursts and Late-Time Geometric Probes
Bruno W. N. Ribeiro, Lázaro L. Sales, Klécio. E. L. de Farias et al. (+3 more)
We investigate the impact of 104 localized FRBs on cosmological parameter estimation when combined with three established late-time probes:
Cosmic Chronometers (CC), Type Ia
Supernovae (SNe), and
Baryon Acoustic Oscillations (BAO). By performing a
Bayesian analysis of three dark energy models ($\Lambda$CDM, $w$CDM, and CPL) and three viable $f(R)$
gravity scenarios – the Appleby-Battye (AB), Hu-Sawicki (HS), and Starobinsky (ST) models – , we find that FRBs substantially improve the constraints on the
baryon density $\Omega_{\rm b}$ by $25\%$–$43\%$, the Hubble constant $H_0$ by $12\%$–$35\%$, and the SNe absolute magnitude $M_B$ by $10\%$–$32\%$. Constraints on dark energy parameters show more modest improvements, with $w$ improving by $\sim 9\%$ in $w$CDM and $(w_0,w_a)$ improving by $\sim(8,22)\%$ in the CPL parametrization. Modified
gravity parameters remain weakly constrained, with improvements of only $6\%$–$15\%$, indicating the limited sensitivity of current
datasets to departures from $\Lambda$CDM. The Figure of Merit analysis shows overall improvements ranging from $\sim 48\%$ ($\Lambda$CDM) to $\sim 91\%$ (CPL), driven by enhanced precision in the $(H_0, \Omega_{\rm b})$ plane. Model comparison reveals moderate statistical preference for extensions beyond $\Lambda$CDM: AIC strongly favors $w$CDM, CPL, HS, and ST with $\Delta\mathrm{AIC} < -7$, and LRT yields $p \leq 0.004$, while BIC returns to positive evidence ($-3.2 < \Delta\mathrm{BIC} < -2.7$). These results show that FRBs may be useful as a complementary probe, particularly for constraining $\Omega_{\rm b}$ and alleviating key late-time degeneracies.
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All authors Bruno W. N. Ribeiro, Lázaro L. Sales, Klécio. E. L. de Farias, Raiff H. Santos, Rafael A. Batista, Amílcar R. Queiroz
Nuclear Theory
Quark and hybrid stars with renormalization group improvement of NNLO perturbative QCD
Loïc Fernandez, Jean-Loïc Kneur, Marcus Benghi Pinto et al. (+3 more)
Recently, the NNLO perturbative QCD pressure of cold and dense symmetric matter, with arbitrary
quark masses, has been resummed within the renormalization-group-optimized perturbation theory (RGOPT) framework. By being imbued with renormalization group properties, the resulting pressure is less sensitive to renormalization scale ($\Lambda\equiv X \mu_B/3$) variations than the NNLO perturbative QCD pressure. Here, we extend this by considering $\beta$-
equilibrium and charge neutrality to evaluate the corresponding equation of state (EoS). We provide a compact “pocket" fitting formula for the EoS for $N_f=2+1$ massive
quarks at different renormalization scale parameter ($X$) values. We describe pure
quark stars as well as hybrid
stars with
quark-cores. Pure
quark stars compatible with astrophysical observations were obtained with $X=2.71-3.30$, whereas a larger value (3.84) is needed if the secondary component of the observation GW190814 represents a
neutron star. Hybrid
stars were built considering three representative
hadron models based on a relativistic mean-field description, and chosen to produce soft and stiff EoSs. Stable hybrid
stars with masses compatible with the massive
pulsar PSR J0740+6620 were obtained considering $X$ of the order of 2 to $2.71$, the largest scale giving rise to hybrid
stars with a large
quark core with a radius of 2 to 8 km , and the smallest to a small
quark core at the center of the
star.
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All authors Loïc Fernandez, Jean-Loïc Kneur, Marcus Benghi Pinto, Constança Providência, Claudia Ratti, Tulio E. Restrepo
Earth and Planetary Astrophysics
The impact of interpolation in high-resolution spectroscopy – The overlooked role of interpolation in radial velocity extraction
A. M. Silva, D. Doshi, K. Al Moulla et al. (+11 more)
We explore the impact of spectral interpolation in radial velocity (RV) time-series extracted through template-based methods. We build synthetic
datasets with Gaussian profiles to evaluate flux residuals and line asymmetry that are a result from changing the sampling location of the lines. We generate synthetic spectra as a sum of Gaussian functions whose parameters were determined through an observed spectrum. The s-BART pipeline was applied to them, allowing to evaluate any biases in RV extraction introduced by its internal assumptions in line shape. Lastly, we apply the s-BART pipeline to ESPRESSO observations of four
stars: two that use high-cadence observations over a single night, and two that have observations spread over multiple nights. When extracting RVs from
stellar spectra, we change the interpolation
algorithm, used in the process of constructing the
stellar template and, afterwards, during RV extraction, comparing them with RVs extracted with a widely-used cubic-spline interpolation. We find that synthetic
datasets reveal systematic biases with the largest peak-to-peak amplitudes reaching $\sim$ 20 m/s in low SNR cases, with the amplitude decreasing as the SNR of the spectra increases. In the extreme case of noise-free data, we still recover a systematic bias, albeit at the mm/s level, significantly smaller than the RV precision of state-of-the-art instruments. With real observations we find that those from high-cadence observations with small BERV variation are impacted by the choice of the interpolation
algorithm. This impact is smaller in higher-SNR cases, where the peak-to-peak amplitude reaches $\sim$ 1 m/s. In the comparatively lower-SNR case we find peak-to-peak residuals as large as $\sim$ 25 m/s . In cases where the observations are spread over a larger BERV window, we find an upper limit of 20 cm/s of RV scatter for this systematic signal.
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All authors A. M. Silva, D. Doshi, K. Al Moulla, E. A. S. Cristo, É. Artigau, P. T. P. Viana, N. C. Santos, J. H. C. Martins, C. M. J. Marques, S. G. Sousa, C. San Nicolas Martinez, T. L. Campante, A. Cabral, S. Cristiani
Mesoscale and Nanoscale Physics
Probing Quantum Geometric Phases via Scanning Tunneling Microscopy
Chao Yan, Mu-Wei Gao, Yue Zhao et al. (+1 more)
The
quantum geometric phase intrinsically dictates the geometry,
topology, and many-body correlations of electronic wave functions. While
quantum geometric phases are conventionally inferred through momentum-space probes or macroscopic transport measurements, their direct visualization and quantification in real space have historically been restricted by the spatial averaging of bulk techniques. Scanning tunneling microscopy and spectroscopy (STM/STS) circumvent this limitation, leveraging atomic-scale spatial resolution and high energy sensitivity to resolve local electronic phase profiles directly. This review highlights recent progress across four representative methodologies: probing the Aharonov-Bohm (AB)
geometric phase via nanoscale real space interferometry; extracting the Berry phase from defect-induced quasiparticle interference and wavefront dislocations; reconstructing the complex phase structure in symmetric systems, such as magic-angle
graphene, using order parameter decomposition; and mapping the phase textures and topological defects of pair density wave (PDW) and charge density wave (CDW) in unconventional
superconductors utilizing the numerical 2D lock-in technique. Together, these developments show how
quantum phases can be translated onto real space and locally resolvable observables. Phase-resolved STM imaging provides stringent constraints on topological states of matter,
symmetry-breaking patterns, and strong electronic correlations, outlining a robust framework for in situ phase engineering in
quantum materials.
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All authors Chao Yan, Mu-Wei Gao, Yue Zhao, Jia-Xin Yin
Quantum Physics
The QAOA on the ring of disagrees
Kunal Marwaha
We study the performance of symmetric local
algorithms finding large cuts on the cycle graph. Such
algorithms that cannot see the whole graph at depth p cut at most a (2p+1)/(2p+2) fraction of edges in expectation. We prove that the QAOA achieves this value, a long-standing
conjecture of Farhi, Goldstone, and Gutmann. Curiously we do this without finding the optimal parameters. Instead we show it is equivalent to find an optimal pair of Laurent
polynomials of degree at most 2p-1. This is made possible by recasting the QAOA on one
qubit in the
language of
quantum signal processing.
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Solar and Stellar Astrophysics
Semi-Empirical Pulsation Reconstruction of Delta Cephei with Photometry, Radial Velocities, and Temperature Constraints
Zuhoor Elahi and Wafa Gull
We present a semi-empirical reconstruction of the pulsation behavior of the classical Cepheid delta Cephei using observed Johnson-V photometry, HARPS-N radial velocities, and published SPIPS pulsation-model curves. A cleaned AAVSO Johnson-V data set was phase folded with P = 5.366531 d, corrected for observer zero-point offsets, clipped for residual outliers, and fitted with a three-harmonic
Fourier template. The resulting empirical template has Delta V about 0.833 mag, R21 about 0.382, R31 about 0.168, and a rise fraction about 0.287. After phase and vertical
alignment, the published SPIPS V-band curve reproduces the empirical Johnson-V morphology with an RMS residual about 0.023 mag. A
Fourier representation of the HARPS-N radial velocities gives a peak-to-peak velocity span about 40.82 km s^-1, corresponding to a preliminary radius-displacement amplitude about 4.81
solar radii for p = 1.317. Combining this radius curve with the SPIPS Teff(phi) curve yields a hybrid luminosity curve close to the published SPIPS luminosity curve. The adopted R0 = 43.7
solar radii scale gives a mean luminosity ratio L_hybrid/L_SPIPS about 1.04, while R0 = 44.9
solar radii gives about 1.10. A direct radius-scale comparison also favors the lower adopted radius scale, with an RMS offset of 0.864
solar radii relative to the SPIPS-implied radius, compared with 2.060
solar radii for the larger-radius case. These results show that the observed visual morphology, radial displacement, and temperature-driven luminosity variation are mutually consistent when placed on a common phase convention, while the absolute radius scale remains the dominant systematic.
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High Energy Physics (Phenomenology)
Probing the structure of $\chi_{c1}(3872)$: Heavy quark symmetries at work
Giuseppe Roselli
More than two decades have elapsed since the discovery of $\chi_{c1}(3872)$. For this
meson, previously denoted as $X(3872)$, an impressive amount of theoretical and experimental studies has been devoted concerning its properties, decays and production mechanisms. Despite the extensive work, a full understanding of the nature of $\chi_{c1}(3872)$ is missing. I describe a theoretical framework based on the heavy
quark large mass limit to analyze the radiative decays of heavy quarkonia, in particular the electric dipole transitions of $\chi_{c1}(2P)$ to $S$-wave charmonia. The results favorably compare to recent LHCb collaboration measurements for $\chi_{c1}(3872)$, if this
meson is identified with $\chi_{c1}(2P)$.
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Mathematical Physics · Cross-listed from math.PR
Propagation of chaos for Belavkin equations beyond pure states
Gaoyue Guo
We use probabilistic and
stochastic-analysis methods to prove trace-norm propagation of chaos for finite-dimensional
quantum mean-field systems governed by Belavkin equations. The particles are density
matrices, interact through a mean-field
Hamiltonian, and are continuously monitored through independent diffusive observation channels. The limiting dynamics is a nonlinear
matrix-valued McKean-Vlasov
diffusion, random through its local observation record and coupled through the deterministic averaged state. The main result treats arbitrary one-particle density
matrices, including mixed states, and both perfect and inefficient measurement regimes. Under strong tensorization of the initial data, every fixed marginal converges uniformly on compact time intervals to the tensor product of the nonlinear limiting filters, with an explicit quantitative bound. The proof combines purification, fully observed dilation, conditional expectation, relative
entropy, and uniform stability of the associated Zakai equations. In the skew-adjoint measurement case, exterior observation noises disappear from the marginal equations and a
stochastic BBGKY hierarchy is recovered. Under only marginal chaoticity of permutation-invariant initial states, we prove convergence of fixed marginals by an iteration of this hierarchy.
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Earth and Planetary Astrophysics
Improving the Precision of Line-by-Line Radial Velocities: A Data-Driven Iterative Algorithm for Spectral Line Selection
Kanishk Pandey, Eric A. Ford, Joseph M. Salzer et al. (+17 more)
Independent analysis of individual spectral lines, or line-by-line (LBL) analyses, can improve upon standard cross-correlation function (CCF) methods for measuring radial velocities (RVs) because they preserve critical information about individual line shape changes that can be caused by
stellar activity. In this work, we measure LBL RVs of 3,830 spectral lines across 383 days of NEID
solar observations. Our LBL approach achieves an RV RMS of $2.012~\mathrm{m\,s^{-1}}$, which is slightly lower than the $2.129~\mathrm{m\,s^{-1}}$ achieved by a CCF approach using a shared line list. Then, we describe and
benchmark several methods for selecting line lists based on line properties such as depth and intrinsic RV scatter. We find that these subsets have a lower RV RMS compared to either the full line list or random subsets of equal size. Motivated by these results, we present
FLARES (Filtering Lines for Accurate Radial-velocity
Exoplanet Search), an iterative line-selection
algorithm.
FLARES selects candidate spectral lines with extreme values of multiple line metrics and properties such as depth, signal-to-noise ratio, and detector position, and preferentially rejects lines whose removal produces the largest decrease in the weighted RV scatter.
FLARES achieves an RV RMS of $1.122~\mathrm{m\,s^{-1}}$ using just 24 lines and performs better than the
benchmark methods. We perform Monte Carlo simulations and show
FLARES is robust and reproducible. Comparisons to alternative line lists chosen to have properties similar to the best
FLARES-selected lines demonstrate that
FLARES is successfully identifying line properties that lead to effective line lists for future extreme-precision RV measurements.
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All authors Kanishk Pandey, Eric A. Ford, Joseph M. Salzer, Jessi Cisewski-Kehe, Lily L. Zhao, Arvind F. Gupta, Michael L. Palumbo III, Ryan C. Terrien, Evan Fitzmaurice, Brady Barth, Jason T. Wright, Cullen H. Blake, Suvrath Mahadevan, Arpita Roy, Joe P. Ninan, Gudmundur Stefansson, Paul Robertson, Christian Schwab, Daniel M. Krolikowski, Leonardo A. Paredes
Optics
Nanometric voids as optical antennas for rewritable momentum-engineered photonics in silicon
Aleksei I. Noskov, Evan P. Garcia, Haiping Sun et al. (+2 more)
Optical
antennas are widely used to localize electromagnetic fields far below the diffraction limit, enabling enhanced light-matter interactions across nanophotonics. Yet the regime in which optical confinement approaches the electronic de Broglie wavelength in a solid - where the
photon momentum distribution broadens sufficiently to relax optical selection rules - remains largely unexplored. Here we show that nanometric voids embedded within crystalline silicon act as such optical
antennas, dramatically altering the optical response of an indirect
semiconductor without the introduction of any foreign material. Using an electrically induced melt-quench process, we generate nanometric voids throughout bulk silicon, confirmed by high-resolution electron microscopy, diffraction analysis,
Fourier-filtered
lattice reconstruction, elemental mapping, and supported by optical and vibrational spectroscopies. The void-containing silicon exhibits intense broadband photo- and electroluminescence spectrally indistinguishable from that produced by metallic or
semiconductor nanoconfiners of similar dimensions, establishing that dielectric discontinuity, not confiner composition, governs the observed momentum-assisted optical transitions. The luminescence can be repeatedly written, erased, and rewritten through alternating electrical conditioning and optical recrystallization. These findings establish nanometric voids as a previously unexplored platform for extreme optical confinement and demonstrate that photonic functionality can be embedded and reconfigured directly within bulk silicon.
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All authors Aleksei I. Noskov, Evan P. Garcia, Haiping Sun, Eric O. Potma, Dmitry A. Fishman
High Energy Physics (Theory)
V. Esrafilian and M. Ali-Akbari
We have studied
holographic entanglement entropy in a moving thermal gauge theory with a non-zero chemical potential. A sufficiently high velocity enhances the
holographic entanglement entropy, particularly for larger values of the chemical potential. However, at high temperature and velocity, the chemical potential dependence is almost entirely washed out, indicating that thermal fluctuations dominate over charge-density effects. In the ultrarelativistic regime, the
holographic entanglement entropy grows very rapidly with velocity, which emerges as the dominant parameter, largely suppressing both thermal and chemical contributions.
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Quantum Physics
Quantum simulation of molecular excited-state manifolds and energies using the TEPID-ADAPT-VQE algorithm
Jason Saroni, Bharath Sambasivam, Ayush Asthana et al. (+1 more)
The simulation of molecular excited states is a key challenge in
quantum chemistry and a promising application for
quantum computing. In this work, we investigate the efficacy of the truncated
eigenvalue parametrized initial density adaptive variational
algorithm (TEPID-ADAPT-VQE) for computing low-lying excited states and potential energy surfaces. TEPID-ADAPT variationally diagonalizes a truncated low-temperature Gibbs state, enabling the simultaneous preparation of multiple excited states within a single optimization. We apply the method to H$_2$, LiH, and linear H$_4$ across bond lengths spanning weakly and strongly correlated regimes. The adaptive derivative-assembled problem-tailored (ADAPT) ansatz construction yields compact
circuits suitable for near-term hardware. We also implement a modified version of the MORE-ADAPT-VQE
algorithm for comparison with TEPID-ADAPT. We find that both
algorithms accurately reproduce excited-state spectra and potential energy curves within chemical accuracy for all the molecules and geometries studied. However, TEPID-ADAPT has the advantage of utilizing only a single, physically motivated hyperparameter (temperature) that controls the energy scale at which excited states are targeted, while MORE-ADAPT utilizes multiple hyperparameters whose optimal values depend sensitively on the target problem. These results demonstrate that combining adaptive ansatz construction with density-
matrix-based formulations provides an efficient framework for excited-state
quantum chemistry on near-term devices.
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All authors Jason Saroni, Bharath Sambasivam, Ayush Asthana, Edwin Barnes
Solar and Stellar Astrophysics
A Reproducible AAVSO Johnson-V Fourier Template for the Prototype Cepheid Delta Cephei
Zuhoor Elahi and Wafa Gull
We present an empirical
Fourier reconstruction of the observed Johnson-V light curve of the prototype Classical Cepheid Delta Cephei. The goal is not to infer a full physical
stellar model but to establish a reproducible observed-light-curve
benchmark for later comparison with nonlinear pulsation, synthetic photometry, Baade-Wesselink/SPIPS, GYRE-supported, and independent hydrodynamic calculations. Using an adopted period of Pobs = 5.366531 d, 244 AAVSO Johnson-V measurements were filtered to a cleaned sample of 242 points after rejecting two extreme outliers. The cleaned data span 355.09259 d and were phase folded using an empirical bright-maximum epoch of JD = 2460851.395800. We fit a low-order
Fourier model to the phased light curve and adopt a third-order template as the preferred empirical morphology representation. The adopted N = 3 fit gives A0 = 3.9031, A1 = 0.3434 mag, A2 = 0.1428 mag, and A3 = 0.0531 mag, corresponding to R21 = 0.4159 and R31 = 0.1547. The template has a full Johnson-V amplitude of Delta V = 0.8544 mag, a rise fraction of frise = 0.2885, and an asymmetry index of Aasym = 0.4230. Bootstrap uncertainties are reported in the manuscript.
Fourier orders N = 4-6 reduce the RMS residual by only about 0.0012 mag relative to the N = 3 model, so the third-order representation is retained as the simplest adequate empirical template. Observer-level residual diagnostics show that the remaining scatter is not purely random. This paper provides an observational morphology target rather than a physical explanation of the pulsation.
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High Energy Physics (Theory)
Observables in Schrödinger CFTs: How Aliens Built the Pyramids
Mathieu Boisvert, Shehab Hossam Fadda, Justin Kulp et al. (+1 more)
We discuss the algebraic structure of observables in Schrödinger CFTs. These operators have zero mass (or particle number) and generically transform in staggered ”pyramid representations” built from ”alien operators,” as we explain with the doubled state-operator correspondence. We comment on implications for the space of non-relativistic CFTs, thermal physics, and generalize the exceptional
symmetry conservation laws of Bekaert, Meunier, and Moroz, and Golkar and Son. We show that alien operators are analogous to double-twist operators in Lorentzian CFT, with systematic cross-channel corrections from massless particles when they exist.
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All authors Mathieu Boisvert, Shehab Hossam Fadda, Justin Kulp, Ramtin M. Yazdi
Strongly Correlated Electrons
Density waves in low-pressure bilayer nickelates
Lauro B. Braz, Steffen Bötzel, Frank Lechermann et al. (+4 more)
The low-pressure phase diagram of La$_3$Ni$_2$O$_7$ provides an important reference for understanding its pressure-induced high-temperature superconductivity. While the
spin-density-wave transition at $T_{\text{SDW}}\approx150$ K is increasingly well established, the origin of the second density-wave transition at $T_{\text{DW}}\approx130$ K has remained unresolved. Here, we perform unrestricted Hartree-Fock calculations to investigate the potential origin of the second transition. {Within the orthorhombic phase, the degeneracy between possible ordering wavevectors at $\boldsymbol{Q}_{Y}=(0,\pi)$ and at $\boldsymbol{Q}_{X}=(\pi,0)$ is lifted and the electronic system} develops a double-stripe
spin-density wave with ordering vector $\boldsymbol{Q}_{Y}=(0,\pi)$. We identify that the pure double stripe
spin state is unstable in La$_3$Ni$_2$O$_7$ towards a commensurate charge-density wave instability, which favors a
spin-modulated double stripe order with intertwined charge and
spin instabilities and establish the hierarchy of ordered states in La$_3$Ni$_2$O$_7$. We further discuss our results in the context of available experimental literature and propose further experimental tests to elucidate the origin of the SDW/DW states in this system.
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All authors Lauro B. Braz, Steffen Bötzel, Frank Lechermann, Igor Plokhikh, Rustem Khasanov, Luis G. G. V. Dias da Silva, Ilya M. Eremin
Data Analysis and Statistics · Cross-listed from cs.LG
Anti-Collapse Dynamics and the Emergence of Multi-Time-Scale Learning in Recurrent Neural Networks
Lorenzo Livi
Long-range learning is hard for recurrent networks trained with
stochastic gradient descent, because the influence of a past input fades with the lag $\ell$, and if it fades too fast the dependence cannot be learned from finite data. This fade is captured by an envelope $f(\ell)$. An exponential fade makes the data needed to learn a lag-$\ell$ dependence grow exponentially, putting long horizons out of reach; a power-law fade keeps the cost
polynomial. We show that the asymptotic decay behavior of $f(\ell)$ is not fixed by the architecture. Instead, it emerges from the coupling between the state dynamics and parameter dynamics, settling into either a collapsed regime (fast, exponential forgetting) or an extended, anti-collapsed regime (slow, power-law forgetting). The intuition is a competition within these coupled dynamics. Training drives the network's effective time scales toward short ones, while rare, heavy-tailed fluctuations of the learning dynamics push a few of them to very long values. Along the route studied here, the extended regime survives only when these heavy-tailed pushes are strong enough to balance the pull. We make this mathematically precise with a coarse-grained
stochastic process and derive an explicit threshold at which this route to the extended regime becomes available. A single exponent, the spectral exponent~$\beta$, then governs both the spread of time scales and how slowly the network forgets. Realizing the regime in practice needs one more ingredient: the joint action of the architecture and the optimizer must be able to hold such a broad spread. A network whose capacity to generate broad time-scale spectra is severely constrained still collapses, even when supplied with strong heavy-tailed forcing. Heavy-tailed fluctuations thus act not as noise to be suppressed, but as the mechanism that sustains long-range learning.
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High Energy Astrophysical Phenomena
Modelling the delayed shock-breakout emission following jet-launching binary neutron star mergers via relativistic magnetohydrodynamic simulations simulations
Matteo Pais, Riccardo Ciolfi and Andrea Pavan
In binary
neutron star (BNS) mergers launching a relativistic jet, an electromagnetic (EM) signal is produced when the jet-driven shock breaks out of the merger ejecta. The observed time delay of this shock-breakout (SBO) emission with respect to the gravitational-wave (GW) signal from the merger provides a powerful probe of the physical conditions governing jet launching and early-time jet propagation. Considering different models of jet propagation in realistic post-merger environments, we investigate the SBO emission and corresponding GW-EM delay that would be observed depending on the viewing angle and the assumed ejecta opacity. We performed relativistic MHD simulations of jets propagating through a post-merger environment directly imported from the outcome of a previous BNS merger simulation. We also introduced a specific procedure to faithfully reconstruct the early dynamical ejecta up to their natural front. The
evolution was followed in 3D up to 0.6 s and then we continued imposing axisymmetry and an eight times higher resolution. Varying jet launching time and luminosity, we identified three representative models spanning regimes from early breakout to extended jet choking. For each case, we tracked the jet-driven forward shock up to the photosphere and computed the angle-dependent bolometric SBO luminosity, and taking into account non-radial
photon propagation, relativistic Doppler shifts, and light-travel-time effects. We considered two opacity values spanning a factor of ten. We find that the GW-EM delay depends only weakly on both the viewing angle and the ejecta opacity, making it, at least for the limited set of configurations considered here, a robust diagnostic for constraining models. Comparing our three cases with GRB 170817A, we find smaller GW-EM delays. Reproducing the same delay will require a broader exploration of the parameter space.
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Mathematical Physics · Cross-listed from math.PR
On uniqueness of solutions to stochastic Navier–Stokes equations
Raymond Cotter and István Gyöngy
Theorems on uniqueness and continuous dependence on the initial condition of solutions to
stochastic Navier-Stokes equations driven by Wiener processes and Poisson martingale measures are presented. These
theorems generalise some results from \cite{GK2026}.
General Relativity and Quantum Cosmology
Radial oscillations of quark stars in light of current astrophysical constraints: A comparative study
G. Panotopoulos, A. Rincon and I. Lopes
We investigate the structural and oscillatory properties of isotropic strange
quark stars within General Relativity, focusing on three physically motivated equations of state: the color
flavor locked (CFL) phase, an interacting
quark matter model, and a linear (causal) equation of state. By numerically solving the Tolman Oppenheimer Volkoff and radial perturbation equations, we construct
equilibrium stellar sequences and compute oscillation spectra across three representative masses (0.77, 1.40, and 2.00
solar masses). Our analysis is focused on two diagnostics: (i) mass to radius profiles and (ii) radial mode eigenfrequencies with large frequency separations. We compare theoretical predictions against multimessenger constraints from NICER X ray timing of key
pulsars, the massive
pulsars at two
solar masses, and the low mass compact object in HESS J1731–347. All three equations of state yield maximum masses exceeding 2
solar masses with canonical mass radii of (10–12) km, satisfying current observational bounds. Fundamental mode frequencies span (4–7) kHz, with asymptotic large separations differing among the models. These elevated frequencies lie within the detection band of current and next generation gravitational-wave observatories, offering potential asteroseismic signatures for distinguishing strange
quark stars from hadronic
neutron stars in post merger emission. Our results demonstrate that self bound
quark matter naturally accommodates the sub
solar mass configuration of HESS J1731–347, reinforcing the viability of strange
quark star interpretations.
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Quantum Gases
Vortex NOON states for rotation sensing
Simon Dengis, Nathan Dupont, Peter Schlagheck et al. (+1 more)
We introduce a scheme to generate NOON states of few-body bosonic
vortices and demonstrate their application as high-precision rotation sensors. Our approach is based on cold atoms in a weakly anisotropic two-dimensional harmonic trap, where the single-particle p orbitals define an effective two-mode Bose-Hubbard model with
vortex modes $(\mathrm{p}_x\pm\mathrm{i}\mathrm{p}_y)$ carrying opposite circulation. In the self-trapping regime, we show that the NOON
manifold becomes spectrally isolated, and collective tunneling processes give rise to highly entangled
vortex NOON states. However, these states emerge on prohibitively long timescales. To overcome this limitation, we develop two complementary acceleration strategies: geodesic counterdiabatic driving for small particle numbers, and resonance- and chaos-assisted tunneling in the semiclassical regime at larger particle numbers. Both approaches enable the generation of NOON states on experimentally relevant timescales while preserving near-unit fidelities. Finally, we quantify the metrological advantage of
vortex NOON states by introducing an interferometric protocol that exploits their intrinsic sensitivity to rotation, enabling the detection of infinitesimal external rotations at the Heisenberg limit. Our work opens the door to rotation sensors based on atomic NOON states, generically realizable in bosonic Josephson junctions with
vortex-type orbitals.
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All authors Simon Dengis, Nathan Dupont, Peter Schlagheck, Nathan Goldman
Astrophysics of Galaxies
Accelerated gas flow along Ophiuchus B44 filament: Breaking Position-Position-Velocity degeneracy
J. Alves, C. Zucker, C. Lada et al. (+15 more)
(Abridged)
Stellar feedback from massive
stars in the Upper-Sco has been proposed to have reshaped the gas in the nearby Ophiuchus complex. In this framework, feedback organizes the gas into two filament types based on their orientation relative to the source of feedback: radial (R-type) filaments, aligned radially to the massive
stars, and tangential (T-type) filaments, which are orthogonal to the feedback direction. A key prediction of this scenario is that gas within R-type filaments should flow longitudinally away from the massive
stars. In this paper, we test this scenario by measuring the three-dimensional gas flow inside the potential R-type filament B44, combining the 3D orientation of the filament from
Gaia-based 3D
dust maps with radial velocities from CO observations. We find that gas flows longitudinally along the B44 filament away from the massive
stars in Upper-Sco with both tracers yielding consistent velocity fields. This result confirms B44 is a R-type filament formed by
stellar feedback from Sco-Cen with an implied filament assembly timescale of $\sim$3~Myr, well within the age of the Upper-Sco massive
stars. Moreover, we find that the gas motion along B44 and away from the massive
stars is accelerated with $a\sim$1.8~km/s/Myr ($\sim 6 \times 10^{-11}$~m/s$^2$). This acceleration is compatible with the accelerations recorded along the Sco-Cen cluster chains over the past $\sim$15~Myr, indicating that B44 is likely a present-day, gas-phase counterpart of the same feedback-driven process that produced those
stellar sequences. We further find evidence for a shock at the wind-facing head of the filament, with a deprojected flow Mach number of $\sim$2 and a matching density jump. Our findings demonstrate that
Gaia 3D
dust maps can lift the line-of-sight ambiguity intrinsic to PPV spectral data, enabling direct deprojection of the gas velocity field in coherent filaments.
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All authors J. Alves, C. Zucker, C. Lada, M. Lombardi, M. Piecka, S. Hutschenreuter, S. Meingast, L. Posch, A. Hacar, K. Tachihara, R. Yamada, C. Swiggum, A. Goodman, R. Wunsch, J. Großschedl, A. Burkert, F. Heitsch, T. Enßlin
Soft Condensed Matter
Emergence of beating in a magnetic flagellum consisting of active bots
Francisca Guzmán-Lastra, Daniel Hernández, Nicolás Quintriqueo et al. (+2 more)
We investigate the emergence of flagellar beating in chains of
magnetic self–propelled particles (MSPPs) built from centimeter–scale vibrating
robots (Hexbugs) with embedded neodymium dipoles. When one end of the chain is anchored and self–propulsion is activated, longitudinal stress accumulates along the chain until it overcomes the
magnetic bending stiffness, triggering a buckling instability that drives sustained flagellar beating. Using a combination of experiments and numerical simulations, we identify three distinct dynamical regimes straight chain, stable flagellar beating, and fission governed by the competition between active force, chain length, and
magnetic bending stiffness. The onset of beating requires a seed misalignment set by the balance between
magnetic torques and rotational noise, and we show that the transition corresponds to a supercritical
Hopf bifurcation. A kinematic model reproduces the observed orientation dynamics with excellent agreement. The
magnetic bending stiffness, which arises directly from dipole–dipole interactions, is fully tunable via dipole strength and chain length, offering independent experimental control over both activity and
rigidity. Our results establish a macroscopic platform for studying force-induced buckling and self–oscillations in active filaments, with direct connections to flagellar motion in biological and synthetic microswimmers.
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All authors Francisca Guzmán-Lastra, Daniel Hernández, Nicolás Quintriqueo, Enkeleida Lushi, Erick Burgos
Quantum Physics
Concentration of Measure Phenomena for Quantum States on a Higher Dimensional Equator
Kabgyun Jeong
We revisit Lévy's lemma, a widely used analytical tool in
quantum information theory. Concentration inequalities quantify the phenomenon in which Lipschitz observables concentrate around a median or mean, and serve as fundamental analytical tools across information theory, statistical physics, and learning theory. In particular, Lévy's lemma provides a crucial framework for describing functionals on pure
quantum states, with applications in
quantum entanglement and
quantum statistical query learning. In this work, we isolate the hyper-equatorial part of the standard spherical concentration argument. The resulting estimate is a Lévy-type bound for Lipschitz functions on a fixed hyperequator, with the natural dimension parameter $d-1$. We also formulate the accompanying
geometric localization in terms of neighborhoods of the boundary, hyperequator, and a codimension-two antipodal great subsphere. This viewpoint clarifies the structure of the usual proof and points to the measure-theoretic formulation needed for sharper constant-level statements.
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Instrumentation and Methods for Astrophysics
Sub-Kelvin Cryogenics for a Super-Pressure Balloon-Borne CMB Polarimeter: Taurus
Jared L. May, Alexandre E. Adler, Jason E. Austermann et al. (+23 more)
Taurus is a balloon-borne
cosmic microwave background (CMB) experiment designed to operate more than 10,000 transition-edge sensor bolometers at a base temperature near 100 mK during a multi-week stratospheric balloon flight. This platform provides near-space observing conditions while imposing stringent constraints on mass, power, and system robustness, driving the need for a lightweight and highly reliable cryogenic system. To meet these requirements, Taurus employs a multi-stage cryogenic architecture. A 660 L
liquid helium tank provides a stable 4 K reservoir, with vapor-cooled shields establishing intermediate stages at approximately 40 K and 80 K. A superfluid helium tank provides an approximately 1.5 K takeoff point for the sub-Kelvin cooling systems. Each of the instrument's three receivers is supported by an independent sub-Kelvin cooling chain that includes closed-cycle 3He sorption refrigerators that cool to 300 mK. These provide the thermal intercept and takeoff for a Chase Research Cryogenics miniature dilution refrigerator that cools the detectors to approximately 100 mK. Here we discuss the requirements and challenges of the Taurus sub-Kelvin cryogenic system and present results of early performance tests.
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All authors Jared L. May, Alexandre E. Adler, Jason E. Austermann, Steven J. Benton, Rick Bihary, Shannon Duff, Malcolm Durkin, Jeffrey P. Filippini, Aurelien A. Fraisse, Thomas Gascard, Sho M. Gibbs, Suren Gourapura, Jon E. Gudmundsson, Johannes Hubmayr, William C. Jones, Ashesh Khatua, Darby McCauley, Johanna M. Nagy, Ivan Padilla, Ricardo R. Rodriguez, John E. Ruhl, M. Shaaf Sarwar, Simon Tartakovsky, Joseph van der List, Michael R. Vissers, Philippe Voyer
Fluid Dynamics
Single-point statistical moments of the nonhomogeneous stochastic advection equation in the small correlation length limit
Keiko Kircher, Cristian Proistosescu and Ryan L. Sriver
This paper presents the derivation of closed-form expressions of the single-point statistical moments of a solution to a nonhomogeneous
stochastic advection equation with a linear relaxation. While analytical solutions exist for homogeneous systems, nonhomogeneous cases have traditionally relied on intensive numerical simulations. Here, we provide an analytical framework for calculating single-point statistical moments by first obtaining the solution to the
stochastic advection equation via the method of characteristics, from which the moments are derived. Explicit, closed-form expressions for the first four moments are derived as functions of the characteristic length scale of the
stochastic velocity field and the spatial derivatives of time-mean profile of the field. The analytical results are validated against numerical simulations, demonstrating excellent agreement across a range of physical parameters. The resulting theory acts as a generalized “equation-of-state" style approach for predicting variability and non-Gaussian statistical behavior directly from the macroscopic mean state, providing applicability across transport systems with a wide range of time and length scales, including geology, hydrology, and atmospheric sciences.
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Quantum Physics
A superconducting qutrit link beyond the qubit limit
Xiang Li, Zheng-Yang Mei, Yang He et al. (+7 more)
Superconducting microwave links have enabled deterministic state transfer and remote
entanglement between
qubits, but deterministic links have so far operated with an effectively two-dimensional transmitted
Hilbert space. Here we demonstrate a superconducting qutrit link between two independently packaged nodes connected by a microwave channel. Each node combines a transmon qutrit, a transmission resonator, and a tunable Purcell-filter interface, allowing the two remote microwave-
photon interfaces to be matched in both frequency and bandwidth. We implement two transition-selective
photon-mediated operations that transfer the $|e\rangle$ and $|f\rangle$ qutrit components in distinct temporal modes of the same channel. We tomographically characterize arbitrary qutrit-state transfer, obtaining a mean transferred-state fidelity of 83.68% and a qutrit process fidelity of 77.12%, exceeding both the classical qutrit-transfer
benchmark and the best possible average fidelity of an effective
qubit channel used to transmit an arbitrary qutrit. Using partial-transfer operations, we reconstruct a remote two-qutrit state with negativity 0.730, a
tomography-inferred dense-coding capacity of 2.273 bits, and a
tomography-inferred Collins-Gisin-Linden-Massar-Popescu (CGLMP) parameter $I_3=2.332$, all beyond the corresponding
qubit or local bounds. These results demonstrate a superconducting microwave link that uses the native three-level structure of transmons as a genuine high-dimensional communication resource.
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All authors Xiang Li, Zheng-Yang Mei, Yang He, Si-Lu Zhao, Yan-Jun Liu, Xiao-Hui Song, Kai Xu, Zhong-Cheng Xiang, Dong-Ning Zheng, Heng Fan
Strongly Correlated Electrons
Orbital-Selective Diagonal-Gap Test of Pairing in La$_3$Ni$_2$O$_7$
Yu-Bo Liu, Zhi-Yan Shao, Zhiming Pan et al. (+2 more)
Recent angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM) measurements on
bilayer nickelate La$_3$Ni$_2$O$_7$ reveal a nearly isotropic, nodeless superconducting gap. We show that these single-particle spectra provide a
symmetry-enforced test of the pairing nature. Mirror
symmetry forces the hybridization between $d_{z^2}$ and $d_{x^2-y^2}$ orbitals to vanish along the Brillouin-zone (BZ) diagonal. Consequently, the gaps on the diagonal portions of the $\alpha/\beta$ and $\gamma$
Fermi pockets separately probe the intrinsic pairing strengths of the $d_{x^2-y^2}$ and $d_{z^2}$ sectors. A pairing state with pure or dominant intrinsic $d_{z^2}$-orbital pairing component produces nodes or near-nodes on the BZ diagonal of the $\alpha/\beta$ pockets and is thus challenged by ARPES and STM, whereas the pairing state with dominant intrinsic $d_{x^2-y^2}$-orbital pairing component has a nearly isotropic, nodeless gap on all pockets which well fits ARPES and STM data. The dominant $d_{x^2-y^2}$-orbital pairing is compatible with Hund's-rule-driven pairing mechanisms.
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All authors Yu-Bo Liu, Zhi-Yan Shao, Zhiming Pan, Chen Lu, Fan Yang
Nuclear Experiment · Cross-listed from cs.LG
Self-Supervised Calibration of Scientific Instruments Using Physical Consistency Constraints
M. Rejmund and A. Lemasson
Calibration remains one of the principal obstacles to the deployment of machine learning in scientific instrumentation because it typically relies on expert intervention, dedicated procedures, and manually labelled data. We introduce a physics-informed self-supervised framework that jointly learns latent detector calibration parameters and task-specific predictions directly from raw measurements without requiring pre-calibrated signals or external labels. The method exploits known physical constraints to generate pseudo-labels iteratively, transforming calibration into a self-supervised optimization problem. The approach is demonstrated for ionic charge-state determination in the VAMOS++
magnetic spectrometer, where the calibration of a segmented ionization chamber and the inference of ionic charge states are learned simultaneously. Starting from a weak prior on the mean ionic charge state, the model progressively refines its predictions through iterative fractional pseudo-labelling driven by the discrete nature of atomic masses. Beyond accurate ionic charge-state reconstruction, the inferred calibration coefficients provide a compact representation of the detector state that enables automated monitoring of gain drifts, pressure variations, and detector aging. The resulting labels can subsequently be transferred to specialized models that quantify detector imperfections and track their spatial and temporal
evolution. These results establish a general paradigm for self-calibrating and self-monitoring scientific instruments and represent a step toward intelligent experimental systems capable of autonomous calibration, analysis, and performance optimization.
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