Nuclear Theory
Implementation of the Moments Method in TALYS: Sensitivity of $^{56,57}$Fe$(n,\gamma)$ observables to shell model nuclear level densities
Lucas Chouinard and Sofia Karampagia
The Moments Method (MM), a statistical spectroscopy framework built upon configuration interaction shell model
Hamiltonians that enables shell model descriptions of
nuclear level densities without requiring full diagonalization of the many body
Hamiltonian, is implemented in the TALYS reaction code to investigate the sensitivity of Hauser-Feshbach calculations for the $^{56}$Fe$(n,\gamma)^{57}$Fe and $^{57}$Fe$(n,\gamma)^{58}$Fe reactions to the
nuclear level density input.
Spin- and parity-dependent MM level densities calculated in the pf shell are interfaced with TALYS and compared with the phenomenological and microscopic level density models available in the code. To construct TALYS-ready inputs, the MM level densities are extended to higher excitation energies using a back shifted
Fermi gas continuation together with an experimentally constrained prescription for opposite-parity states. A sensitivity band for the MM calculations is estimated by varying a single parameter governing the statistical reconstruction of the level density.
Neutron capture cross sections, Maxwellian averaged cross sections, and reaction rates are compared with evaluated ENDF/B-VIII.0 data and recommended KADoNiS and JINA-CEE values to assess the relative importance of the
nuclear level density and $\gamma$-ray strength function inputs. The calculations show that the observables are considerably more sensitive to the choice of $\gamma$-ray strength function than to the MM level density variation considered here, while the MM-based results remain in good agreement with evaluated cross sections and recommended astrophysical reaction rates.
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Mesoscale and Nanoscale Physics
Tuning single-molecule fluorescence by atomic-scale control of the local environment
Thiago G. L. Brito, Daniel Arribas, Sofia Canola et al. (+3 more)
Molecules that absorb and emit light play a central role in microscopy, light-emitting devices and photosynthesis. Their fluorescence arises from well-defined radiative transitions that are governed by the electronic states and their coupling to the
nuclear motion that are influenced by the local environment. Yet the effect of controlled atomic-scale variations in the emitter surroundings remains unexplored. Here, we use scanning tunneling microscopy combined with optical spectroscopy to investigate the optical response of a single phthalocyanine to the change in the position of a nearby molecule, controlled with precision better than 100 pm. Upon decreasing the intermolecular distance, the molecular emission energy
redshifts and its line profile evolves. Supported by theoretical calculations, we disentangle the electronic and
nuclear contributions to the changes in fluorescence. We find that the
redshift originates from the interaction between the excitations of the two molecules, while the lineshape changes reflect modifications of the molecular rotational degree of freedom and non-
equilibrium dynamics. We extend this control to larger assemblies, where one molecule tunes the energies of two chromophores, mimicking the environmental tuning in photosynthetic systems. Our study provides atomic-scale insight into how the local environment affects the optical properties of molecular systems.
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All authors Thiago G. L. Brito, Daniel Arribas, Sofia Canola, Klaus Kuhnke, Tomáš Neuman, Anna Rosławska
Astrophysics of Galaxies
Identifying AGNs from X-ray detections$-$II: Metallicity calibrations for the $\rm N_2O_2$ and $\rm N_2S_2$ diagnostics
Mark Armah, O. L. Dors, Rogério Riffel et al. (+4 more)
Emission-line ratios from ions with nearly identical ionization potentials offer a robust solution to the degeneracies inherent to traditional active
galactic nuclei (AGNs)
metallicity diagnostics. We introduce new semi-empirical
metallicity calibrations for the $\rm N_2O_2$ and $\rm N_2S_2$ diagnostics, explicitly designed to isolate the chemical abundance from the incident radiation field. By coupling an extensive grid of CLOUDY photoionization simulations directly to the intrinsic 2$-$10 keV X-ray luminosity ($L_{\rm X}$) and benchmarking against Seyfert~2
nuclei from the Burst Alert
Telescope AGN Spectroscopic Survey (BASS), we establish robust relations valid across the
metallicity regime of $8.0 \lesssim 12+\log({\rm O/H}) \lesssim 9.1$ ($0.2 \lesssim Z/Z_{\odot} \lesssim 2.6$). The $\rm N_2O_2$ and $\rm N_2S_2$ indices trace co-spatial emitting volumes within the narrow-line regions (NLRs), enabling this framework to resolve the significant $L_{\rm X}$-driven systematic biases we previously identified in the standard $\rm N_2$ and $\rm N_2O_3$ indices. While the $\rm N_2O_2$ ratio proves to be virtually independent of nebular structural variations, the $\rm N_2S_2$ index exhibits a subtle, yet discernible, electron density ($N_{\rm e}$) susceptibility due to the low critical density ($N_{\rm c}$) of the [S II]$\lambda\lambda6716,6731$ doublet. Nevertheless, both diagnostics yield highly precise
metallicity constraints with tight root-mean-square residual dispersions of $\sim 0.081$ dex for $\rm N_2O_2$ and $\sim 0.121$ dex for $\rm N_2S_2$. We propose the $\rm N_2O_2$ and $\rm N_2S_2$ calibrations as highly optimized, unbiased
metallicity tracers for AGNs.
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All authors Mark Armah, O. L. Dors, Rogério Riffel, M. V. Cardaci, G. F. Hägele, Rogemar A. Riffel, J. M. Vílchez
Solar and Stellar Astrophysics
Eta Carinae's historical light curve: evidence for cyclic Roche lobe overflow from the primary star
Augusto Damineli, Leonardo A. Almeida, Francisco J. Jablonski et al. (+5 more)
The large amount of ground-based photometric measurements of $\eta$ Carinae obtained since 1940 have remained problematic for quantitative modeling due to the blending of flux from the
stellar core and the surrounding circumstellar nebula. In the era of the Hubble Space
Telescope, spatially resolved imaging & spectrophotometry have enabled disentanglement of these components, allowing recovery of the
stellar core $V$-band brightness from ground-based observations. We isolate the $V$-band fluxes of the
stellar core and nebula using 1999–2020 HST (ACS and STIS) observations, and use these to calibrate coeval ground-based photometry. The main finding is an orbital light curve with an amplitude $\Delta m \approx \pm 0.2\,$mag, many times higher than that modeled by ellipsoidal deformation of the primary. The observations suggest that Roche lobe overflow starts at $- 75$ days before periastron in coincidence with the start of rising in the orbital light curve, and remains for 150 days. An expanding (and afterwards dissipating) gas cloud reflecting the light from the primary would explain the observed large amplitude of the orbital light curve. A sharp periodic photometric peak occurs at $\sim -18$ days from the periastron. It is followed by a broad minimum around the superior conjunction of the secondary (T$_0+5.2$ days), which we interpret as a partial eclipse of the ejected material, in coincidence with the shallow minimum in X-rays, which also has been attributed to an eclipse.
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All authors Augusto Damineli, Leonardo A. Almeida, Francisco J. Jablonski, Eduardo Fernández-Lajús, Felipe Navarete, Eder Martioli, Gerd Weigelt, Rodrigo Capobiango
Earth and Planetary Astrophysics
Eclipse Timing of the Eccentric Planet HD 80606b with JWST: Constraints on a Second Planet and other Dynamical Effects
Charles Beichman, Billy Quarles, B.J. Fulton et al. (+6 more)
A variety of effects can perturb the orbital properties of single
planets in close orbits around their host
stars. HD80606 b is a highly eccentric ($\epsilon$=0.93)
exoplanet orbiting its host G5V
star, HD80606. HD80606 b became a compelling target for
exoplanet research after (Laughlin et al 2009) discovered that the 4.16 MJup
planet transits and is eclipsed by HD80606, thereby enabling photometric and spectroscopic observations to yield a wealth of information about the object. The exquisite precision of recent JWST eclipse timing offers an opportunity to investigate whether the orbit of HD80606 b is modified due to a variety of mechanisms, including General Relativity,
tidal torques, or the presence of a second perturbing
planet. We have used over 25 years of radial velocity data plus eclipse and transit observations to place limits on the precession of HD80606 b's orbit and to assess which of these effects, if any, are observable. The new models are consistent with constant values of period, eccentricity and the argument of periastron, $\omega$, with a limit on $\dot{\omega}$ at the level of the predicted GR drift. The PRV and timing data limit the mass and location of a second
planet external to HD80606b. Timing offsets between JWST eclipses relative to the Pearson et al (2022) predictions are attributed to the poor constraints on $\sqrt{\epsilon} (\cos\ \omega, \sin\ \omega)$ with only the single eclipse measurement available (Spitzer 2009) in that analysis and to an over-weighting of the eclipse timing in that earlier analysis.
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All authors Charles Beichman, Billy Quarles, B.J. Fulton, Nikole Lewis, Ryan Challener, Julien de Wit, Malena Rice, Julie Inglis, Tiffany Kataria
Quantum Physics
Hundred-hertz quantum circuit iteration rate in a reusable neutral-atom array
Liang Chen, Wen-Yi Zhu, Dong-Qi Ma et al. (+16 more)
Neutral-atom
quantum processors have rapidly advanced in scale and coherence, yet their practical performance remains constrained by limited
quantum circuit iteration rates (qCIRs) and information throughput. Here we experimentally demonstrate a high-throughput neutral-atom system based on non-destructive readout and atom reuse. By integrating a chip-based photonic interface with a 10-
qubit array, we implement non-destructive readout with a retention probability of 99.7%, and further achieve a raw qCIR of 101Hz and a post-selected qCIR of 74.8Hz. More importantly, we verify a general throughput optimization methodology and obtain a normalized Fisher information rate of 57.7Hz, improving the achievable throughput by more than one order of magnitude compared with conventional methods. Our results establish a practical route toward high-throughput neutral-atom
quantum processors.
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All authors Liang Chen, Wen-Yi Zhu, Dong-Qi Ma, Tian-Yang Zhang, Zi-Jie Chen, Yi-Chen Zhang, Hong-Jie Fan, Guang-Jie Chen, Qing-Xuan Jie, Wei-Zhou Cai, Tian-Cai Zhang, Luyan Sun, Yan-Lei Zhang, Xi-Feng Ren, Guang-Can Guo, Zhu-Bo Wang, Ya-Dong Hu, Gang Li, Chang-Ling Zou
Optics
Fabrication-Aware Inverse Design of Nanophotonic Devices for 3D Laser-Nanoprinting
Oliver Kuster, Tim Alletzhäusser, Carsten Rockstuhl et al. (+2 more)
Advances in 3D
laser-nanoprinting enable us to fabricate 3D nanophotonic devices with a wide range of functionalities on demand. By exploiting all three spatial dimensions, an enormous design space becomes available for these nanophotonic devices. However, such an immense design space is impossible to explore efficiently by intuition alone, especially when designing free-form nanophotonic devices. Density- based
topology optimization offers a natural tool for 3D nanophotonic design by allowing the efficient design of devices with millions of degrees of freedom. Traditional density-based
topology optimization relies on heuristic measures to account for limitations imposed by the fabrication method. Indeed, the fabrication method is rarely considered as part of the forward model in the design pipeline. In this work, we introduce an inverse design method that explicitly models the direct-
laser-writing process used in 3D nanoprinting. Incorporating a differentiable formulation of the direct-
laser-writing model allows us to design 3D nanophotonic devices within the experimentally available design space and to precompensate for fabrication-specific effects. Optimizing inside the experimentally available design space ensures that the constraints we put on the optimization are given by our parametrization of the fabrication method and not by heuristic methods, which might over- or underconstrain the optimization problem. Furthermore, modeling the 3D
laser-nanoprinting process explicitly allows us to not only take fabrication-specific effects, such as the proximity effect, into account but also enables the optimization to actively make use of these fabrication-specific effects to increase the functionality of the device.
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All authors Oliver Kuster, Tim Alletzhäusser, Carsten Rockstuhl, Martin Wegener, Thomas Jebb Sturges
Mesoscale and Nanoscale Physics
Surface weak ferromagnetism
Vladimir A. Zyuzin
This paper proposes a model of a Néel-ordered antiferromagnet exhibiting a weak
ferromagnetic moment restricted to the
crystal surface, generated by
spin-orbit coupling induced by broken surface
symmetries. Depending on
crystal termination, the surface
magnetic moment can align with identical or opposing signs on the top and bottom surfaces, resulting in a zero Faraday effect paired with a finite Kerr effect upon reflection for the latter configuration.
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Optics
Parallel Spatial Photonic Programming of Optoelectronic IGZO RRAM with a compact $\mu$LED Array
Andrew Adair, Joshua Robertson, Andreas Tsiamis et al. (+6 more)
Optoelectronic resistive random-access
memory elements (ORRAM) are critical emerging devices that leverage photonic technologies to bring the advantages of optical programming to traditionally electronic memristive platforms for neuromorphic computing and artificial intelligence. In this work, a free-space optic micro-LED ($\mu$LED) array is combined with a 2-terminal
oxide semiconductor ORRAM (based on IGZO\textsubscript{Rich}/IGZO active layers), to realise parallel spatial programming of form-free memristive arrays. We report the optical and electrical programming of resistive states with potentiation/depression analysis of various stimuli parameters (pulse frequency, pulse width, pulse amplitude). Further, we demonstrate the simultaneous photonic-electronic programming of the ORRAM with optical SET (blue 450\,nm) and electrical RESET functionality. Persistent photocurrent is also observed and exploited as a pathway to fading
memory or synaptic plasticity for temporal bit encoding. Finally, parallel optical $\mu$LED to ORRAM channels are demonstrated to achieve the simultaneous photonic programming of multiple devices and the writing of spatial patterns across a chip of memristive IGZO devices. This work highlights the light-enabled scalability of the optoelectronic platform and the feasibility of ORRAM to interface with spatially-multiplexed optical sources to bring neuromorphic technologies directly into applications that process and sense in the optical domain.
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All authors Andrew Adair, Joshua Robertson, Andreas Tsiamis, Mohamed Awadein, Spyros Stathopoulos, Johannes Herrnsdorf, Martin D. Dawson, Themis Prodromakis, Antonio Hurtado
Astrophysics of Galaxies
JWST Whirlpool Galaxy Treasury: Mid-Infrared Emission in M51 and its Relation to Gas Column and Star Formation
Mansi Padave, Karin M. Sandstrom, Daniel A. Dale et al. (+25 more)
Using JWST/MIRI imaging of M51 in eight broadband filters, we investigate correlations of mid-infrared emission from polycyclic aromatic hydrocarbons (PAHs) and
dust continuum with molecular, atomic, and ionized gas traced by CO(1-0), HI, and Pa-alpha, respectively. In molecular gas-dominated regions, PAH-dominated filters (F560W, F770W, F1130W, F1280W) exhibit near-linear correlations with CO(1-0) at 40 pc scale, indicating that PAHs are well-mixed with gas and experience relatively constant radiation field intensities. The F1500W, F1800W, and F2100W
dust continuum-dominated filters show shallower slopes with CO(1-0), reflecting contributions from
star-forming regions with high radiation field intensities. This is reinforced by the near-linear scaling between F2100W and Pa-alpha. PAH-dominated bands do not show this linear trend with Pa-alpha, likely due to their destruction in ionized regions. F1000W behaves similarly to PAH bands in its correlations with CO(1-0) and Pa-alpha. Modeling mid-infrared emission with an empirical decomposition into gas- and
star-formation-associated components shows that PAH-dominated filters receive comparable contributions from both, while the relative contribution associated with the Pa-alpha template increases toward longer wavelengths, reaching $\sim$75% in F2100W. These results demonstrate that mid-infrared simultaneously traces the gas column and
star formation, but with a systematic wavelength-dependent shift in what drives the correlations: PAHs being more gas-tracing and
dust-continuum reflecting
star formation. Lastly, considering both HI and H$_2$ at 440 pc resolution, we find a tight, linear relation between $\Sigma_{HI+H_2}$ and PAH-dominated filters. Although most of our coverage is in H$_2$-dominated regions, we note similar observations with HI, suggesting that PAHs are also well-mixed with atomic gas.
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All authors Mansi Padave, Karin M. Sandstrom, Daniel A. Dale, Adam K. Leroy, Eric W. Koch, Tony D. Weinbeck, Angela Adamo, Jessica Sutter, Lindsey Hands, Torsten Böker, Martha L. Boyer, Ryan Chown, Bruce T. Draine, Ilse de Looze, Brandt A. L. Gaches, Simon C. O. Glover, Dario Colombo, Robert C. Kennicutt Jr., Hannah Koziol, Ralf S. Klessen, Sean T. Linden, Desika Narayanan, Alex Pedrini, Julia Roman-Duval, Eva Schinnerer, J.D.T. Smith, Sophia K. Stuber, Fabian Walter
High Energy Astrophysical Phenomena
A Cross-Band (X-ray $\times$ Optical) Periodicity Search for Supermassive Black Hole Binaries: A Null Result and the First Completeness-Corrected Constraint
Karan Akbari
We present the first sample-level search for supermassive black hole binaries (SMBHBs) requiring coherent quasi-periodicity at a common period in the X-ray and optical bands, over 1194 Swift-BAT hard X-ray AGN (Stage 1) and 175 4XMM-DR14 AGN (Stage 2). No source is a co-periodic candidate. Each light curve is modelled as a damped random walk (DRW) and searched with a Lomb-Scargle periodogram and a look-elsewhere-corrected Monte-Carlo significance. Because DRW red noise is largely independent between corona and disc, we require both bands individually significant with periods coincident within 5%, and gate the survivors with the model-independent null-signal-template test of Robnik et al. (2024). Over $P=100$-$900$ d the completeness-corrected 95% upper limit on the co-periodic fraction is amplitude-dependent: $\lesssim 3\%$ for hard-X-ray fractional modulation $\gtrsim 0.3$, $\approx 15\%$ (precision-limited) at 0.2, and uninformative below $\sim 0.15$ (the $\epsilon=1$ floor is 0.25%). The sensitivity is set by the hard X-ray monitoring, not the optical photometry or the statistics, the opposite of the usual assumption. Daily MAXI and RXTE/ASM monitoring of the brightest AGN raises the X-ray completeness 5-8-fold, and the search remains null. Integrated over the BAT black-hole mass function, the expected all-amplitude co-periodic fraction is $\sim 3\times10^{-2}\, f_{\rm bin}\, \delta_{\rm mod}$ (modulo a factor $g<1$), with $f_{\rm bin}$ the sub-pc binary fraction, $\delta_{\rm mod}$ the modulating duty cycle, and $g$ the fraction reaching recoverable hard-X-ray amplitude, so a null is expected. We deliver a validated cross-band framework and the first completeness-corrected constraint on the co-periodic fraction, ready for the denser X-ray monitoring of Einstein Probe and eROSITA.
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High Energy Physics (Phenomenology)
Exotics with gluonic excitations
Jozef J. Dudek
That the
gluons of
quantum chromodynamics self-interact with a strong coupling suggests the possibility of
hadrons in which the gluonic field plays an essential role: Glueballs in which
gluons stick together to produce a
hadron in which no
quarks are required, and hybrids in which an excited gluonic field couples to
quarks. This chapter presents our contemporary theoretical understanding of such states, and the challenges associated with definitively identifying their presence within the experimental spectrum of
hadrons.
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Lattice Field Theory
Quantum Simulation of QCD in Axial Gauge
Xiaojun Yao
We study
quantum simulation of SU(3) non-Abelian gauge theory dynamically coupled with fundamental
fermions in $3+1$ dimensions by employing the
lattice Hamiltonian in axial gauge that avoids Gauss's law constraints. The temporal component of the gauge field is analytically solved in terms of independent field degrees of freedom and a
lattice regulated Green's function. The axial gauge condition is trivially maintained in time
evolution, even under Trotterization. The gauge field degrees of freedom are expressed in the local field basis and can be efficiently transformed into the canonical conjugate momentum basis by local
quantum Fourier transforms. We prove the number of
qubits needed for describing all states up to an energy $E$ with an accuracy $\epsilon$ on a
lattice of volume $V$ at bare coupling $g$ is bounded as $16n_A V + 12n_f V$, where $n_A \approx \log_2 (\frac{64 E' V^{4/3}}{\pi^2\epsilon} + \frac{32\sqrt{2}g n_f E'^{1/2} V^{7/6}}{\sqrt{3}\pi^3\epsilon^{1/2}} ) $ is the number of
qubits needed for each independent gauge field per site with a shifted energy $E'$, and $n_f$ denotes the number of
fermion flavors. We then analyze a
quantum algorithm for time
evolution that is based on Trotterization,
quantum Fourier transform, and Jordan-Wigner transformation, for which
quantum circuits can be explicitly constructed under arbitrary gauge field truncation and digitization. We find the numbers of CNOT and single-
qubit rotation gates both scale as $O(n_A^4 V^{4/3}) + O(V^{5/3})$ per Trotter step for fixed $n_f\leq 6$. We conclude that
quantum resources needed for simulating real-time dynamics of
lattice QCD scale polynomially with volume, energy, time, accuracy, and bare
Hamiltonian parameters.
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Soft Condensed Matter
Approximation of anisotropic pairwise interactions for charged objects using multivariate polynomials and a multipole expansion
Mohammadreza Fakhraei, Dylan McElheny, Chris A. Kieslich et al. (+1 more)
We formulate a physics-informed data-driven method for modeling anisotropic pairwise interactions in the presence of long-ranged electrostatics. The method separates the total interaction into a long-ranged electrostatic interaction that is approximated using a multipole expansion truncated at the dipole level and a short-ranged residual interaction that is approximated using multivariate Chebyshev
polynomials fit to measurements from a limited number of configurations. We assess the approach on a sequence of aromatic molecules (benzene, benzonitrile, and phenoxide), finding that it produces satisfactory results using a modest cutoff distance for the short-ranged interaction. This method has applications for modeling complex interactions for, and conducting dynamic simulations of, synthetic and biological materials with charge.
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All authors Mohammadreza Fakhraei, Dylan McElheny, Chris A. Kieslich, Michael P. Howard
High Energy Physics (Theory)
Higher spin dynamics in Weyl reference frame
Gianfranco De Simone
In this manuscript we derive the $w_{1+\infty}$
algebra on an arbitrary null hypersurface located at finite distance. A straightforward integration of the
evolution Bianchi identities is performed in a suitable dynamical reference frame, dubbed the Weyl reference frame. In this reference frame, the extraction of the (linear) higher
spin charge bracket is similar to the asymptotic null case, except that the corner metric evolves non trivially in time. In other words, boundary degrees of freedom that are frozen at null infinity due to the boundary conditions now become part of the dynamics. This feature is reflected in the appearance of non-local terms in the brackets. In order to avoid the presence of these non-local terms in the charge bracket, we absorb this non-locality - which encodes nothing other than the history of the corner metric - into the definition of the higher
spin charges. Moreover, a new perspective on the
memory effect at finite distance is suggested. In conclusion, we believe that this treatment can also be applied to asymptotically (A)dS$_{4}$ spacetimes, where the presence of a non-vanishing cosmological constant leads to the introduction of a cosmological reference frame.
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High Energy Astrophysical Phenomena
Inclination Diffusion in Relativistic Loss Cones
Wenkang Xin
Relativistic capture and
tidal disruption around a spinning black hole depend on both the magnitude and direction of the
star's angular momentum, yet loss-cone models often assume fixed orbital inclinations by ignoring the associated
diffusion. We show that this is not justified: for isotropic two-body relaxation near a small loss threshold, angular-momentum magnitude $L$ and inclination $x = L_{z}/L$ diffuse on comparable timescales, $t_{E} \gg t_{L} \sim t_{x}$. For Kerr capture, retaining inclination
diffusion significantly amplifies the prograde–retrograde contrast while leaving the total inclination-integrated flux nearly unchanged. An almost correct integrated flux can hide a badly wrong angular distribution. The three-dimensional
diffusion problem nevertheless retains enough angular structure to permit analytic treatment. By representing pericenter removal as a continuous sink, we obtain a closed-form loss flux solution for a nearly linear Kerr
tidal-disruption boundary, finding close agreement with phase-resolved calculations. Inclination-dependent loss therefore requires inclination-resolved
diffusion even when integrated rates appear robust.
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Nuclear Theory
Nuclear Drip Line and the Composition of Supernova Matter
S. Maity and S. Mallik
The
nuclear drip line plays a crucial role in determining the composition of matter under extreme astrophysical conditions. In core-collapse
supernovae and
neutron-
star crusts, matter is driven far from saturation density and
nuclear stability;
nuclei coexist with a sea of free
neutrons, an effect that is present even at zero temperature in
neutron-
star crusts and becomes more pronounced in the hotter,
neutron-rich
supernova environment. This makes a careful treatment of drip-line physics essential for a realistic description of the equation of state and composition. In this work, the influence of the
nuclear drip line on the baryonic composition of
supernova matter is investigated within the framework of
nuclear statistical
equilibrium (NSE). The composition is evaluated in terms of free nucleons, light clusters, and heavy
nuclei at finite temperature and global sub-saturation densities. The results indicate that, at low
proton fractions and higher densities, the inclusion of
nuclei beyond the drip line enhances the formation of extremely
neutron-rich light clusters, leading to a significant reduction in the free-
neutron density and the charge fraction of heavy
nuclei. These findings demonstrate that drip-line physics has a significant impact on the composition of
supernova matter and should be carefully incorporated in
supernova modeling and nucleosynthesis studies.
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Materials Science
Automated Burgers Vector Identification for Individual Dislocations in Bulk Crystals
Abderrahmane Benhadjira, Carsten Detlefs, Vincent Favre-Nicolin et al. (+4 more)
Weak-beam imaging in dark-field X-ray microscopy (DFXM) can resolve individual dislocations in bulk
crystals, but assigning Burgers vectors from the resulting contrast typically requires manual comparison with forward simulations. Here, we train a physics-informed convolutional neural network (CNN) on geometrical optics simulations of isolated dislocations in face-centred cubic (FCC) aluminium, incorporating crystallographic constraints into the learning pro- cess. The model identifies Burgers vectors from weak-beam integrated rocking-curve images. On synthetic test data, the model achieves an accuracy of approximately 93%. In an experimental cross-slip case, the constrained model as- signs 72.7% of the layer-wise predictions to the reference Burgers vector. These results show that simulation-trained, physics-informed CNNs represent a step toward automated dislocation identification in DFXM.
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All authors Abderrahmane Benhadjira, Carsten Detlefs, Vincent Favre-Nicolin, Henning Friis Poulsen, Grethe Winther, Can Yildirim, Sina Borgi
High Energy Physics (Theory)
Linear Dilaton in Cosmology and Particle Physics
Eugenio Megias and Mariano Quiros
A warped extra dimension in a five-dimensional (5D) anti-de Sitter (AdS) background was introduced in 1999 by Lisa Randall and Raman Sundrum to solve the gauge hierarchy problem in particle physics. As a bonus, a
holographic interpretation in terms of four-dimensional (4D) conformal field theories (CFTs) was found. Interestingly enough, another 5D background, linear dilaton (LD), was found to have a
holographic interpretation in terms of Little String Theory. In this review, we will show how a set of 5D backgrounds, parametrized in terms of a real parameter $\nu$, generalizes both theories and gives rise, in particular, to AdS for $\nu=0$ and to LD for $\nu=1$. Furthermore, working in the 5D theory, we will consider applications of the LD background to: (i) particle physics, so that the 5D Planck scale can be lowered to sub-Planckian values, and (ii) Brane World Cosmology (BWC), based on the appearance of an extra
vacuum characterized by a 5D black hole. In all cases, we find a gapped continuum for bulk propagating fields, which makes a connection with unparticles. In the case of BWC, we also point out the existence of a pressureless
holographic fluid that could play the role of dark matter (DM), with feeble (gravitational) interactions with the Standard Model (SM), decoupled from the thermal SM bath, and generated by a freeze-in mechanism after inflation. We also point out the additional possibility of identifying DM with a long-lived, feebly interacting massive graviton, as an isolated resonance generated by radiative corrections to the continuum graviton propagator self-energy.
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Astrophysics of Galaxies
A posteriori correction of Gaia CRF proper motions using conditional probability and zero-parallax prior
Valeri V. Makarov
The formal precision of
Gaia CRF proper motions, and in principle positions, can be statistically improved by introducing conditional probability based on the zero-parallax prior for these extremely distant sources. The method developed in this study produces statistically conditioned proper-motion estimates under the assumed per-source Gaussian covariance model. It is demonstrated that thus corrected proper motion vectors of 1.2 million CRF objects in
Gaia DR3 show a tighter distribution around zero and a general reduction in the rate of outliers by approximately 15%. A general vector spherical harmonic fit to degree 4 is produced with the corrected data for a filtered subset of CRF
quasars with
redshifts between 1 and 1.5. This application, predicated on the unknown
stochastic component of the global parallax field, shows a 3-sigma change in the estimated magnitude of the Galactocentric acceleration of the
solar system barycenter, quantifying the sensitivity of this fundamental determination to the proposed conditioning of proper motions.
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General Relativity and Quantum Cosmology
On the (Non)Unitarity with respect to the Clock of a Dynamical Local Observer and the Einstein Equivalence Principle
Kengo Shimada
We investigate the unitarity of
quantum evolution relative to an internal time defined by a local observer's clock. The observer is modeled as a relativistic particle carrying both a clock and a matter-field detector, analyzed first on a fixed curved background and subsequently within a fully diffeomorphism-invariant theory of dynamical
gravity. In the former case, we find that
evolution with respect to the internal clock time is generally nonunitary, implying a violation of the Einstein equivalence principle at the
quantum level. In contrast, in the latter case, diffeomorphism invariance allows us to adopt observer-centric coordinates without loss of generality. On the resulting partially-reduced phase space, one of the diffeomorphism generators becomes linear in the clock
Hamiltonian, generating a relational
evolution that is consistent with the remaining diffeomorphism constraints. Assuming that an effective
quantum field theory exists to be consistent with the diffeomorphism invariance, these features ensure
unitary evolution relative to the internal clock, thereby preserving the equivalence principle even in the
quantum regime. Our results highlight the fundamental role of diffeomorphism invariance in shaping relational
unitary evolution from the perspective of a local observer.
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Physics and Society
Spectral Fingerprints of Street-Network Morphology: A Size-Adjusted Graph-Laplacian Descriptor of Urban Fabric
Piotr C. Kaminski
Decades of space-syntax research have established that the
topology of the street network conditions movement, co-presence and urban activity. The standard vocabulary for this – integration, choice and connectivity – summarises each street's position as a scalar centrality, yet two streets with identical centrality can sit in radically different morphological fabric. We introduce a compact, comparable, machine-learning-ready encoding of that local fabric: the spectral fingerprint, a fixed-dimensional kernel-density representation of the graph-
Laplacian eigenvalue distribution of each node's k-hop ego subgraph, computed on the COINS dual graph of the street network. From it we derive two interpretable scalar readouts: the Mesh Index (MI), a normalised spectral
entropy, and the Connectivity Resilience Index (CRI), the algebraic connectivity (Fiedler value). Both are corrected for an ego-subgraph-size confound that dominates raw spectral statistics. Applied to the full street network of Poznan, Poland (1,908 continuity-based strokes), the descriptor is robust to its encoding hyperparameters (spectral resolution and kernel bandwidth; Spearman rho >= 0.98) while remaining scale-dependent in its neighbourhood radius. The size adjustment leaves the Mesh Index near-orthogonal to integration (r = 0.06), carrying information classical centrality does not. The fingerprint separates morphological tissue types without supervision, and the Mesh Index is associated with the functional diversity of street-adjacent activity at the neighbourhood scale (r ~ 0.19, on open OpenStreetMap data). We delineate the method's scope honestly: it characterises what kind of activity a street's position affords, not the price that activity commands. It offers an information-theoretic morphological descriptor that complements space syntax and is directly consumable by modern graph-learning pipelines.
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Astrophysics of Galaxies
High Velocity Neutral Gas in the Fermi Bubbles: New Kinematic Limits and Spatial Structure
Felix J. Lockman, Enrico M. Di Teodoro, Savannah Cary et al. (+1 more)
We have detected hundreds of neutral clouds entrained in the Milky Way's
nuclear wind using HI data from new surveys made with the Green Bank
Telescope that cover about 500 sq-degrees around the
Galactic center (GC).
Galactic winds are common throughout the Universe, and these data at 9.1' angular resolution (22 pc at the GC) provide the most detailed analysis of the vertical profile of a neutral
nuclear wind in any
galaxy. A set of 228 of these
Fermi Bubble clouds with the largest values of |VLSR| has been analyzed to examine the distribution and kinematics of the outflowing gas. The clouds span -335 km/s $\leq$ VLSR $\leq$ +438 km/s, the largest positive LSR velocities ever reported for neutral HI associated with the Milky Way disk. The highest velocities are found furthest from the GC, suggesting that clouds are accelerated from a low velocity near the
nucleus to at least 500 km/s at a radial distance of $\lesssim 4$ kpc. Clouds appear disrupted as they are accelerated: their line brightness and NHI decreases steadily with distance from the GC, and the population becomes more uniform. There is an abrupt cutoff in the neutral clouds at a vertical distance of $\approx2$ kpc from the
Galactic plane. Kinematic models of an outflowing cloud population that fills the FB volume are used to identify structure in the gas. The kinematics of the highest velocity, highest latitude clouds imply a past azimuthal asymmetry in the
outflow.
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All authors Felix J. Lockman, Enrico M. Di Teodoro, Savannah Cary, Andrew J. Fox
Mesoscale and Nanoscale Physics
Classical Mechanics Exactly Yields the Full Bound-State Spectrum of the Two-Dimensional Coulomb Problem
Gang Zheng, Wenqi Xue, Mengli Wang et al. (+2 more)
High-lying Rydberg
excitons in two-dimensional
semiconductors universally exhibit a characteristic odd-integer energy scaling distinct from three-dimensional systems. While this hallmark of two-dimensional Coulomb interaction is well known from
quantum mechanical solutions, its deeper classical
geometric origin remains unclarified. Here we show that the complete bound-state spectral structure of the two-dimensional Coulomb problem—a central model for two-dimensional
exciton physics—follows as an exact
theorem from classical mechanics augmented by a single phase-scale parameter $\alpha$ with dimensions of action. We derive an amplitude-closure criterion as a necessary and sufficient condition for a classical propagator kernel to satisfy a linear
evolution equation, and demonstrate that the singular Coulomb potential can be mapped shell-by-shell via Levi-Civita regularization into the class of quadratic
Hamiltonians that obey this criterion exactly. The resulting spectrum bears odd-integer modal numbers, $1/N^2$ energy ratios and $N$-fold degeneracies, all independent of $\alpha$ and consistent with experimental observations of high-lying Rydberg
excitons. This work provides a pure classical-geometry
benchmark for two-dimensional
exciton spectral analysis, allowing quantitative disentanglement of universal Coulomb effects from material-specific screening effects. No semiclassical, short-wavelength or $\hbar \to 0$ approximation is invoked at any stage. Our results invert the usual logical hierarchy for this integrable system: the wave equation emerges as a representation of the underlying classical geometry, rather than as an independent first principle.
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All authors Gang Zheng, Wenqi Xue, Mengli Wang, Peng Chen, Benniu Zhang
Fluid Dynamics
A diffuse-interface method for compressible two-phase flows with seven- and six-equation models
Luis H. Hatashita and Suhas S. Jain
In this work, a novel phase-field method is proposed for the six- and seven-equation non-
equilibrium models for simulating compressible two-phase flows. Such formulations allow for monotonic mixture speed of sound, minimizing artificial wave delay during transmission across an interface. The proposed phase field formulation is constructed from the baseline seven-equation model, and interface-regularization terms are added in divergence form, while maintaining consistency between the partial differential equations without introducing spurious source terms. It admits conservative phasic and mixture
entropy transport equations, thus facilitating the construction of discrete conservative schemes. The six-equation formulation is obtained under instantaneous velocity
equilibrium. To avoid eigenvector degeneracy of the system of PDEs, the volumetric interface regularization flux is modified to account for a finite amount of conjugate phase, which improves on how phasic density is captured implicitly. Stability of compressible two-phase flow rely on the preservation of the interface-
equilibrium conditions, and the preservation of discrete kinetic energy and
entropy. A detailed analysis of IEC demonstrates additional requirements on the consistency of flux splittings between the convective and interface-regularization terms for all quantities, as well as the effects on the phasic internal energy flux splittings. A KEEP discretization is proposed and evaluated over a suite of high-density ratio test cases, including interface advection, acoustic wave-induced bubble oscillation, oblique acoustic wave reflection and transmission, and two-phase Taylor-Green
vortex flow. Results demonstrate accuracy, stability and robustness for very long time integrations, a desired feature for simulation of turbulent flows and acoustics, since the framework does not rely on the addition of numerical dissipation.
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High Energy Physics (Phenomenology)
Two-loop tensor integral reduction for automated tools
Fabian Lange and Max F. Zoller
In order to exploit the full potential of the LHC and future
colliders, high-precision calculations of a very wide range of observables are crucial. Automated tools for next-to-next-to-leading order calculations of perturbative scattering amplitudes are therefore a highly desirable goal. So far, we have developed several major ingredients of such a tool in the OpenLoops framework. In our approach we split the calculation of scattering amplitudes into three components: loop momentum tensor integrals, the corresponding process-dependent tensor coefficients, and the interplay of $(D-4)$-dimensional parts of the integrand with divergences of the integrals. In these proceedings, we present a new recursive
algorithm to reduce arbitrary two-loop tensor integrals to scalar integrals, which has been implemented into an efficient numerical tool. We also implemented a first version of the subsequent reduction to master integrals, which allows for a full validation of the
algorithm. We present a first successful validation computation and discuss its dependence on the precision of the externally computed master integrals.
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Instrumentation and Methods for Astrophysics
Anti-windup PI controller for millimeter-wave adaptive optics: a Nobeyama 45 m radio telescope simulation
Ichiro Jikuya, Yoichi Tamura, Akio Taniguchi et al. (+8 more)
This work addresses the control problem for Millimeter-wave Adaptive Optics (MAO), which we define as compensating for the distance variation between the primary reflector (M1) and the receiver. We utilize a measurement system developed by Tamura et al. to track these variations. The challenge is formalized as an asymptotic constant disturbance suppression problem. We demonstrate that an anti-windup proportional-integral (AWPI) controller effectively solves this problem while respecting the physical movement constraints of the optical driving system. Simulation results, based on the Nobeyama 45-m
Telescope with a two-axis translating sub-reflector (M2), validate the performance of the proposed AWPI approach.
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All authors Ichiro Jikuya, Yoichi Tamura, Akio Taniguchi, Masaki Sakakibara, Akinobu Miyake, Masato Hagimoto, Kianhong Lee, Chihiro Imamura, Shion Takeno, Sachiko S. Okumura, Nozomi Okada
High Energy Physics (Theory) · Cross-listed from math.NT
Galois descents of certain multiple polylogarithms
Yajun Zhou
We prove some
conjectures of K. C. Au concerning the descents of cyclotomic levels in certain sums over multiple polylogarithms. Via answers to a question of Au in some particular cases, we also confirm Broadhurst's
conjecture on honorary multiple
zeta values at even weights.
Space Physics
In-situ measurements of space plasma: recent progress and future challenges
Daniel Verscharen
Space
plasmas like the
solar wind or the Earth's space environment offer unique opportunities to observe fundamental
plasma processes and their impact in situ. With modern space instrumentation, we measure the velocity distribution function of the
plasma particles as well as the electromagnetic fields at high resolution and with minimal perturbation of the observed
plasma systems.
Plasma measurements like this are often not possible in laboratory settings on Earth. This review article focuses on modern diagnostic methods for the in-situ detection of
plasma particles in space. It presents the detection principle of top-hat electrostatic analysers and highlights recent examples of scientific discoveries based on data from the heliospheric space missions Parker
Solar Probe and
Solar Orbiter. These examples demonstrate the capabilities of modern space
plasma instrumentation. The article then discusses future directions in space
plasma physics as well as the involved challenges in terms of the required
plasma diagnostics. These new developments include, for example, upcoming and proposed space missions such as the operational space-weather mission Vigil, the multi-spacecraft mission HelioSwarm, the Mars mission M-MATISSE, and the electron-astrophysics mission Debye.
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Quantum Physics
The preferred-time problem in the conditional interpretation of time
Ovidiu Cristinel Stoica
In timeless formulations of
quantum theory, the Page-Wootters proposal (PW) recovers time and dynamics as relative clock-and-world states. By interpreting the total timeless system as a clock entangled with the world, the states having a definite clock reading appear to recover the temporal states of the world as relative states, and dynamics emerges. But an entangled state admits infinitely many decompositions as a superposition of product states, each decomposition corresponding to a different but equally valid time operator of the same clock system. Different valid choices of the time operator for the same clock system lead to different physical histories, where the world states in a history are superpositions of the world states from another history. Fixing one operator as "the" clock time would import the temporal meaning that the Page-Wootters proposal is meant to explain in the first place. Therefore, the interpretation of PW that the world state is passively conditioned on the clock state cannot hold. The timeless state is resolved into time-dependent states by the intrinsic pointer observables of the world, without having to outsource the role of the time operator to a separate clock. Fortunately, the formalism of PW remains valid, provided that it is interpreted in terms of intrinsic pointer observables of the world itself.
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