{"results":[{"id":"doaj_10.1038/s42005-025-02475-6","title":"Reinforcement learning with learned gadgets to tackle hard quantum problems on real hardware","authors":[{"name":"Akash Kundu"},{"name":"Leopoldo Sarra"}],"abstract":"Abstract Quantum computing offers exciting opportunities for simulating complex quantum systems and optimizing large-scale combinatorial problems, but its practical use is limited by device noise and constrained connectivity. Designing quantum circuits, which are fundamental to quantum algorithms, is therefore a central challenge in current quantum hardware. Existing reinforcement learning-based methods for circuit design lose accuracy when restricted to hardware-native gates and device-level compilation. Here, we introduce gadget reinforcement learning (GRL) that combines learning with program synthesis to automatically construct composite gates that expand the action space while respecting hardware constraints. We show that this approach improves accuracy, hardware compatibility, and scalability for transverse-field Ising and quantum chemistry problems, reaching systems of up to ten qubits within realistic computational budgets. This framework demonstrates how learned, reusable circuit building blocks can guide the co-design of algorithms and hardware for quantum processors.","source":"DOAJ","year":2026,"language":"","subjects":["Astrophysics","Physics"],"doi":"10.1038/s42005-025-02475-6","url":"https://doi.org/10.1038/s42005-025-02475-6","is_open_access":true,"published_at":"","score":70},{"id":"doaj_10.3847/1538-4357/ae2610","title":"Is There a Retrograde Accretion Disk around 4U 1626–67? Tracking Torque Reversals with a State-space Model","authors":[{"name":"Joseph O’Leary"},{"name":"Andrew Melatos"},{"name":"Tom Kimpson"},{"name":"Dimitris M. Christodoulou"},{"name":"Nicholas J. O’Neill"},{"name":"Patrick M. Meyers"},{"name":"Sayantan Bhattacharya"},{"name":"Silas G. T. Laycock"}],"abstract":"X-ray timing studies of the persistent, Galactic, accretion-powered pulsar 4U 1626−67 reveal torque reversals, during which the pulse frequency ν ( t ) alternates between multiyear episodes of secular acceleration and deceleration, separated by transitions lasting ≲150 days. Here an unscented Kalman filter is applied to track the ν ( t ) fluctuations observed in 22.7 yr (3340 samples) of publicly available Compton Gamma-Ray Observatory and Fermi Gamma-Ray Space Telescope data to test the canonical picture of magnetocentrifugal accretion for consistency with prograde–prograde and retrograde–prograde accretion disk configurations on either side of the 2008 torque reversal. It is found that the retrograde–prograde model is preferred, with a log Bayes factor equal to 0.44 and a maximum a posteriori log likelihood ratio equal to 2.5. The mass accretion rate Q ( t ) and magnetocentrifugal fastness ω ( t ) transition smoothly between episodes of deceleration and acceleration: Q ( t ) shifts by ≤0.34 dex across the reversal, and one measures ω ( t ) ≈ 0.25 and ω ( t ) ≈ 0.30 during deceleration and acceleration, respectively. The angular acceleration $\\dot{{\\rm{\\Omega }}}(t)$ satisfies $-9\\,\\lesssim \\,\\dot{{\\rm{\\Omega }}}(t)/(1{0}^{-12}\\,{\\rm{rad}}\\,{{\\rm{s}}}^{-2})\\,\\lesssim \\,-5$ and $2\\,\\lesssim \\,\\dot{{\\rm{\\Omega }}}(t)/(1{0}^{-12}\\,{\\rm{rad}}\\,{{\\rm{s}}}^{-2})\\,\\lesssim \\,9$ before and after the 2008 reversal, respectively, compared to $\\dot{{\\rm{\\Omega }}}\\approx -3.0\\,\\times 1{0}^{-12}\\,{\\rm{rad}}\\,{{\\rm{s}}}^{-2}$ before reversal and $\\dot{{\\rm{\\Omega }}}\\approx 2.5\\times 1{0}^{-12}\\,{\\rm{rad}}\\,{{\\rm{s}}}^{-2}$ after reversal, as inferred from previous long-term X-ray timing and spectral analysis of 4U 1626−67.","source":"DOAJ","year":2026,"language":"","subjects":["Astrophysics"],"doi":"10.3847/1538-4357/ae2610","url":"https://doi.org/10.3847/1538-4357/ae2610","is_open_access":true,"published_at":"","score":70},{"id":"arxiv_2510.01112","title":"The causal structure of galactic astrophysics","authors":[{"name":"Harry Desmond"},{"name":"Joseph Ramsey"}],"abstract":"Data-driven astrophysics currently relies on the detection and characterisation of correlations between objects' properties, which are then used to test physical theories that make predictions for them. This process fails to utilise information in the data that forms a crucial part of the theories' predictions, namely which variables are directly correlated (as opposed to accidentally correlated through others), the directions of these determinations, and the presence or absence of confounders that correlate variables in the dataset but are themselves absent from it. We propose to recover this information through causal discovery, a well-developed methodology for inferring the causal structure of datasets that is however almost entirely unknown to astrophysics. We develop a causal discovery algorithm suitable for large astrophysical datasets and illustrate it on $\\sim$4.5$\\times10^5$ nearby galaxies from the Nasa Sloan Atlas, demonstrating its ability to distinguish physical mechanisms that are degenerate on the basis of correlations alone.","source":"arXiv","year":2025,"language":"en","subjects":["astro-ph.GA","astro-ph.CO","cs.LG","stat.AP","stat.ME"],"doi":"10.33232/001c.159080","url":"https://arxiv.org/abs/2510.01112","pdf_url":"https://arxiv.org/pdf/2510.01112","is_open_access":true,"published_at":"2025-10-01T16:55:49Z","score":69},{"id":"arxiv_2508.07859","title":"The reflex instability: exponential growth of a large-scale $m=1$ mode in astrophysical discs","authors":[{"name":"Aurélien Crida"},{"name":"Clément Baruteau"},{"name":"Jean-François Gonzalez"},{"name":"Frédéric Masset"},{"name":"Paul Segrétain"},{"name":"Philippine Griveaud"},{"name":"Héloïse Méheut"},{"name":"Elena Lega"}],"abstract":"We report the finding of a linear, non-axisymmetric, global instability in gas discs around stars, which may be relevant to other astrophysical discs. It takes the form of an $m=1$ mode that grows in the disc density distribution while the star-barycentre distance rises exponentially with a characteristic timescale that is orders of magnitude longer than the orbital period. We present results of hydrodynamical simulations with various codes and numerical methods, using either barycentric or stellocentric reference frames, with or without the disc's self gravity: all simulations consistently show an unstable mode growing exponentially.   The instability disappears if, and only if, the reflex motion of the star due to the disc's asymmetry is not taken into account in the simulations. For this reason we refer to this instability as the reflex instability. We identify a feedback loop as a possible origin, whereby the acceleration of the star excites the eccentricity of the disc, yielding an $m=1$ mode in the density distribution which, in turn, pulls the star. The growth timescale of the instability decreases with increasing disc mass and is a few hundred orbits for disc-to-star mass ratios of a few percent. If truly physical, and not due to a numerical artifact that would be common to all the codes we have employed, the reflex instability could have a dramatic impact on protoplanetary discs evolution and planetary formation.","source":"arXiv","year":2025,"language":"en","subjects":["astro-ph.EP","astro-ph.GA","astro-ph.SR"],"doi":"10.33232/001c.143230","url":"https://arxiv.org/abs/2508.07859","pdf_url":"https://arxiv.org/pdf/2508.07859","is_open_access":true,"published_at":"2025-08-11T11:19:40Z","score":69},{"id":"arxiv_2510.18531","title":"Improved thermonuclear rate of $^{42}$Ti($p$,$γ$)$^{43}$V and its astrophysical implication in rp-process","authors":[{"name":"S. Q. Hou"},{"name":"C. Iliadis"},{"name":"M. Pignatari"},{"name":"J. B. Liu"},{"name":"T. C. L. Trueman"},{"name":"J. G. Li"},{"name":"X. X. Xu"}],"abstract":"Accurate $^{42}$Ti($p$,$γ$)$^{43}$V reaction rates are crucial for understanding the nucleosynthesis path of the rapid capture process (rp-process) that occurs in X-ray bursts. We aim to improve the thermonuclear rates of $^{42}$Ti($p$,$γ$)$^{43}$V based on more complete resonance information and accurate direct component, together with the recently released nuclear masses data. We reevaluated the $^{42}$Ti($p$,$γ$)$^{43}$V rate by the sum of the isolated resonance contribution instead of the Hauser-Feshbach statistical model. A Monte Carlo method is used to derive the uncertainties of new rates. The nucleosynthesis simulations are performed via the NuGrid post-processing code ppn. The new rates differ from previous estimations because of using a series of updated resonance parameters and direct S-factor. Compared with the previous results from Hauser-Feshbach statistical model, which assumes compound nucleus $^{43}$V with a sufficiently high-level density in the energy region of astrophysical interest, differences exist over the entire temperature region of rp-process interest, even up to 4 orders of magnitude. Using a trajectory with a peak temperature of 1.95$\\times$10$^9$ K, we perform the rp-process nucleosynthesis simulations to investigate the impact of the new rates. Our calculations show that the adoption of the new forward and reverse rates result in abundance variations for Sc and Ca by 128\\% and 49\\% respectively compared to the case using statistical model rates. On the other hand, the overall abundance pattern is not significantly affected. The results of using new rates also confirm that the rp-process path does not bypass the isotope $^{43}$V. It is found that the Hauser-Feshbach statistical model is inappropriate to the reaction rate evaluation for $^{42}$Ti($p$,$γ$)$^{43}$V.","source":"arXiv","year":2025,"language":"en","subjects":["astro-ph.SR"],"doi":"10.1051/0004-6361/202347054","url":"https://arxiv.org/abs/2510.18531","pdf_url":"https://arxiv.org/pdf/2510.18531","is_open_access":true,"published_at":"2025-10-21T11:19:40Z","score":69},{"id":"doaj_10.3847/1538-4357/adb61d","title":"The JWST Resolved Stellar Populations Early Release Science Program. VIII. The Spatially Resolved Star Formation History of WLM","authors":[{"name":"Roger E. Cohen"},{"name":"Kristen B. W. McQuinn"},{"name":"Alessandro Savino"},{"name":"Max J. B. Newman"},{"name":"Daniel R. Weisz"},{"name":"Andrew E. Dolphin"},{"name":"Martha L. Boyer"},{"name":"Matteo Correnti"},{"name":"Marla C. Geha"},{"name":"Mario Gennaro"},{"name":"Karoline M. Gilbert"},{"name":"Nitya Kallivayalil"},{"name":"Jack T. Warfield"},{"name":"Benjamin F. Williams"},{"name":"Alyson M. Brooks"},{"name":"Andrew A. Cole"},{"name":"Evan D. Skillman"},{"name":"Christopher T. Garling"},{"name":"Jason S. Kalirai"},{"name":"Jay Anderson"}],"abstract":"Radial stellar population gradients within dwarf galaxies provide a promising avenue for disentangling the drivers of galaxy evolution, including environment. Within the Local Volume, radial stellar age gradient slopes correlate with interaction history, contrary to model predictions, so dwarfs that are isolated provide a critical control sample. We measure radial stellar age gradients in the relatively isolated gas-rich dwarf irregular Wolf–Lundmark–Melotte Galaxy (WLM), combining JWST NIRCam and NIRISS imaging with six archival Hubble Space Telescope fields over semimajor axis equivalent distances of 0 ≲  R _SMA  ≲ 4 kpc (≲3 R _hl ). Fitting lifetime star formation histories to resolved color–magnitude diagrams, radial age gradients are quantified using τ _90 and τ _50 , the lookback times to form 90% and 50% of the cumulative stellar mass. We find that globally, the outskirts of WLM are older on average, with ( δτ _90 , δτ _50 )/ δ R _SMA  = (0.82 ${}_{-0.10}^{+0.10}$ , 1.60 ${}_{-0.22}^{+0.23}$ ) Gyr kpc ^−1 (stat.), in good agreement with simulations. However, we also detect an azimuthal dependence of radial stellar age gradients, finding that stars on the leading edge of WLM (relative to its proper motion) are both younger and have a flatter age gradient compared to the trailing edge. This difference persists over 0.6 ≲  R _SMA  ≲ 3.2 kpc (∼0.5–2.5 R _hl ) and lookback times up to ∼8 Gyr, and is robust to the assumed stellar evolutionary model. Our results are consistent with star formation triggered by ram pressure stripping from a circumgalactic and/or intergalactic medium, suggested by recent H I observations. If confirmed, processes typifying dense environments, such as ram pressure stripping, may be more relevant to the evolution of isolated galaxies than previously thought.","source":"DOAJ","year":2025,"language":"","subjects":["Astrophysics"],"doi":"10.3847/1538-4357/adb61d","url":"https://doi.org/10.3847/1538-4357/adb61d","is_open_access":true,"published_at":"","score":69},{"id":"doaj_10.3390/axioms14060440","title":"Complex Riemannian Spacetime: Removal of Black Hole Singularities and Black Hole Paradoxes","authors":[{"name":"John W. Moffat"}],"abstract":"An approach is presented to resolve key paradoxes in black hole physics through the application of complex Riemannian spacetime. We extend the Schwarzschild metric into the complex domain, employing contour integration techniques to remove singularities while preserving the essential features of the original solution. A new regularized radial coordinate is introduced, leading to a singularity-free description of black hole interiors. Crucially, we demonstrate how this complex extension resolves the long-standing paradox of event horizon formation occurring only in the infinite future of distant observers. By analyzing trajectories in complex spacetime, we show that the horizon can form in finite complex time, reconciling the apparent contradiction between proper and coordinate time descriptions. This approach also provides a framework for the analytic continuation of information across event horizons, resolving the Hawking information paradox. We explore the physical interpretation of the complex extension versus its projection onto real spacetime. The gravitational collapse of a dust sphere with negligible dust is explored in the complex spacetime extension. The approach offers a mathematically rigorous framework for exploring quantum gravity effects within the context of classical general relativity.","source":"DOAJ","year":2025,"language":"","subjects":["Mathematics"],"doi":"10.3390/axioms14060440","url":"https://www.mdpi.com/2075-1680/14/6/440","is_open_access":true,"published_at":"","score":69},{"id":"doaj_10.1088/2632-2153/ae1f05","title":"Towards instance-wise calibration: local amortized diagnostics and reshaping of conditional densities (LADaR)","authors":[{"name":"Biprateep Dey"},{"name":"David Zhao"},{"name":"Brett H Andrews"},{"name":"Jeffrey A Newman"},{"name":"Rafael Izbicki"},{"name":"Ann B Lee"}],"abstract":"Key science questions, such as galaxy distance estimation and weather forecasting, often require knowing the full predictive distribution of a target variable Y given complex inputs X . Despite recent advances in machine learning and physics-based models, it remains challenging to assess whether an initial model is calibrated for all x , and when needed, to reshape the densities of y toward ‘instance-wise’ calibration. This paper introduces the local amortized diagnostics and reshaping of conditional densities (LADaR) framework and proposes a new computationally efficient algorithm ( Cal-PIT ) that produces interpretable local diagnostics and provides a mechanism for adjusting conditional density estimates (CDEs). Cal-PIT learns a single interpretable local probability–probability map from calibration data that identifies where and how the initial model is miscalibrated across feature space, which can be used to morph CDEs such that they are well-calibrated. We illustrate the LADaR framework on synthetic examples, including probabilistic forecasting from image sequences, akin to predicting storm wind speed from satellite imagery. Our main science application involves estimating the probability density functions of galaxy distances given photometric data, where Cal-PIT achieves better instance-wise calibration than all 11 other literature methods in a benchmark data challenge, demonstrating its utility for next-generation cosmological analyzes ^9 .","source":"DOAJ","year":2025,"language":"","subjects":["Computer engineering. Computer hardware","Electronic computers. Computer science"],"doi":"10.1088/2632-2153/ae1f05","url":"https://doi.org/10.1088/2632-2153/ae1f05","is_open_access":true,"published_at":"","score":69},{"id":"doaj_10.3847/1538-4357/adcd61","title":"XMM-Newton Observations of the High Temperature Plasma in the Large Magellanic Cloud Supernova Remnant N132D","authors":[{"name":"Adam R. Foster"},{"name":"Paul P. Plucinsky"},{"name":"Terrance J. Gaetz"},{"name":"Xi Long"},{"name":"Diab Jerius"}],"abstract":"We present an analysis of the archival XMM-Newton observations of the Large Magellanic Cloud (LMC) supernova remnant N132D totaling more than 500 ks. We focus on the high temperature plasma ( kT _e  ∼ 4.5 keV) that is responsible for the high energy continuum and exciting the Fe K emission. An image analysis shows that the Fe K emission is mainly concentrated in the southern part of the remnant interior to the region defined by the forward shock. This Fe K distribution would be consistent with an asymmetric distribution of the Fe ejecta and/or an asymmetric interaction between the reverse shock and the Fe ejecta. We compare the EPIC-pn and EPIC-MOS spectra in the 3.0–12.0 keV bandpass with a model based on RGS data plus a higher temperature component, in collisional ionization equilibrium (CIE), or nonequilibrium (both ionizing and recombining). We find that the data are equally well fitted by the CIE and ionizing models. Assuming the CIE and ionizing spectral models, the Fe in this high temperature component is significantly enhanced with respect to typical LMC abundances. We can place only an upper limit on the neutral Fe K line. We conclude that the Fe K emission is due to ejecta heated by the reverse shock given the spatial distribution, relatively high temperature, and enhanced abundance. We estimate the progenitor mass based on the Ca/Fe and Ni/Fe mass ratios to be 13 ≤ M _P ≤ 15 M _⊙ .","source":"DOAJ","year":2025,"language":"","subjects":["Astrophysics"],"doi":"10.3847/1538-4357/adcd61","url":"https://doi.org/10.3847/1538-4357/adcd61","is_open_access":true,"published_at":"","score":69},{"id":"doaj_10.1140/epjc/s10052-025-13835-5","title":"Polarized $$W^+W^-$$ W + W - pairs at the LHC: Effects from bottom-quark induced processes at NLO QCD + EW","authors":[{"name":"Thi Nhung Dao"},{"name":"Duc Ninh Le"}],"abstract":"Abstract We investigate the effects of the bottom-quark induced processes on the doubly polarized cross sections of $$W^+W^-$$ W + W - pair production at the LHC. The method to extract the on-shell single-top contribution is provided. Results for phenomenological and experimental analyses are given at next-to-leading order (NLO) QCD + EW accuracy, with the leading contribution from the gluon–gluon and photon–photon fusion included. We found that the contribution of the bottom-quark induced processes, after the subtraction of the on-shell tW channel, is largest for the doubly longitudinal polarization. At the integrated cross section level, using a fiducial ATLAS cut with a jet veto, the effect is $$9\\%$$ 9 % compared to the NLO value of the light-quark contribution. It increases to $$13\\%$$ 13 % after removing the jet veto. A bound of the tW interference is calculated for various kinematic distributions, showing that this interference effect is, in general, smaller for the no jet veto case. Relevant scale uncertainties are calculated to help us decide on the importance of this interference.","source":"DOAJ","year":2025,"language":"","subjects":["Astrophysics","Nuclear and particle physics. Atomic energy. Radioactivity"],"doi":"10.1140/epjc/s10052-025-13835-5","url":"https://doi.org/10.1140/epjc/s10052-025-13835-5","is_open_access":true,"published_at":"","score":69},{"id":"doaj_10.3847/2041-8213/ada697","title":"Magnetic Reconnection–driven Energization of Protons up to ∼400 keV at the Near-Sun Heliospheric Current Sheet","authors":[{"name":"M. I. Desai"},{"name":"J. F. Drake"},{"name":"T. Phan"},{"name":"Z. Yin"},{"name":"M. Swisdak"},{"name":"D. J. McComas"},{"name":"S. D. Bale"},{"name":"A. Rahmati"},{"name":"D. Larson"},{"name":"W. H. Matthaeus"},{"name":"M. A. Dayeh"},{"name":"M. J. Starkey"},{"name":"N. E. Raouafi"},{"name":"D. G. Mitchell"},{"name":"C. M. S. Cohen"},{"name":"J. R. Szalay"},{"name":"J. Giacalone"},{"name":"M. E. Hill"},{"name":"E. R. Christian"},{"name":"N. A. Schwadron"},{"name":"R. L. McNutt Jr."},{"name":"O. Malandraki"},{"name":"P. Whittlesey"},{"name":"R. Livi"},{"name":"J. C. Kasper"}],"abstract":"We report observations of direct evidence of energetic protons being accelerated above ∼400 keV within the reconnection exhaust of a heliospheric current sheet (HCS) crossing by NASA’s Parker Solar Probe (PSP) at a distance of ∼16.25 solar radii ( R _s ) from the Sun. Inside the exhaust, both the reconnection-generated plasma jet and the accelerated protons up to ∼400 keV propagated toward the Sun, unambiguously establishing their origin from HCS reconnection sites located antisunward of PSP. Within the core of the exhaust, PSP detected stably trapped energetic protons up to ∼400 keV, which is ≈1000 times greater than the available magnetic energy per particle. The differential energy spectrum of the accelerated protons behaved as a pure power law with spectral index of ∼−5. Supporting simulations using the kglobal model suggest that the trapping and acceleration of protons up to ∼400 keV in the reconnection exhaust are likely facilitated by merging magnetic islands with a guide field between ∼0.2 and 0.3 of the reconnecting magnetic field, consistent with the observations. These new results, enabled by PSP’s proximity to the Sun, demonstrate that magnetic reconnection in the HCS is a significant new source of energetic particles in the near-Sun solar wind. Our findings of in situ particle acceleration via magnetic reconnection at the HCS provide valuable insights into this fundamental process, which frequently converts the large magnetic field energy density in the near-Sun plasma environment and may be responsible for heating the Sun’s atmosphere, accelerating the solar wind, and energizing charged particles to extremely high energies in solar flares.","source":"DOAJ","year":2025,"language":"","subjects":["Astrophysics"],"doi":"10.3847/2041-8213/ada697","url":"https://doi.org/10.3847/2041-8213/ada697","is_open_access":true,"published_at":"","score":69},{"id":"arxiv_2402.18990","title":"The astrophysical parameters of chemically peculiar stars from automatic methods","authors":[{"name":"Ernst Paunzen"}],"abstract":"The chemically peculiar (CP) stars of the upper main sequence are excellent astrophysical laboratories for investigating the diffusion, mass loss, rotational mixing, and pulsation in the presence and absence of a stable local magnetic field. For this, we need a homogeneous set of parameters, such as effective temperature and surface gravity, to locate the stars in the Hertzsprung-Russell diagram so that we can then estimate the mass, radius, and age. In recent years, the results of several automatic pipelines have been published; these use various techniques and data sets, including effective temperature and surface gravity values for millions of stars. Because CP stars are known to have flux anomalies, these astrophysical parameters must be tested for their reliability and usefulness. If the outcome is positive, these can be used to analyse the new and faint CP stars published recently. I compared published effective temperature and surface gravity values of a set of CP stars, which are mostly based on high-resolution spectroscopy, with values from four automatic pipeline approaches. In doing so, I searched for possible correlations and offsets. I present a detailed statistical analysis of a comparison between the `standard' and published effective temperature and surface gravity values. The accuracy depends on the presence of a magnetic field and the spectral type of the CP subgroups. However, I obtain standard deviations of between 2% and 20%. Considering the statistical errors, the astrophysical parameters from the literature can be used for CP stars, although caution is advised for magnetic CP stars.","source":"arXiv","year":2024,"language":"en","subjects":["astro-ph.SR","astro-ph.IM"],"doi":"10.1051/0004-6361/202348086","url":"https://arxiv.org/abs/2402.18990","pdf_url":"https://arxiv.org/pdf/2402.18990","is_open_access":true,"published_at":"2024-02-29T09:43:56Z","score":68},{"id":"doaj_10.3390/e26030260","title":"Restoring the Fluctuation–Dissipation Theorem in Kardar–Parisi–Zhang Universality Class through a New Emergent Fractal Dimension","authors":[{"name":"Márcio S. Gomes-Filho"},{"name":"Pablo de Castro"},{"name":"Danilo B. Liarte"},{"name":"Fernando A. Oliveira"}],"abstract":"The Kardar–Parisi–Zhang (KPZ) equation describes a wide range of growth-like phenomena, with applications in physics, chemistry and biology. There are three central questions in the study of KPZ growth: the determination of height probability distributions; the search for ever more precise universal growth exponents; and the apparent absence of a fluctuation–dissipation theorem (FDT) for spatial dimension \u003cinline-formula\u003e\u003cmath xmlns=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"\u003e\u003csemantics\u003e\u003cmrow\u003e\u003cmi\u003ed\u003c/mi\u003e\u003cmo\u003e\u003e\u003c/mo\u003e\u003cmn\u003e1\u003c/mn\u003e\u003c/mrow\u003e\u003c/semantics\u003e\u003c/math\u003e\u003c/inline-formula\u003e. Notably, these questions were answered exactly only for \u003cinline-formula\u003e\u003cmath xmlns=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"\u003e\u003csemantics\u003e\u003cmrow\u003e\u003cmn\u003e1\u003c/mn\u003e\u003cmo\u003e+\u003c/mo\u003e\u003cmn\u003e1\u003c/mn\u003e\u003c/mrow\u003e\u003c/semantics\u003e\u003c/math\u003e\u003c/inline-formula\u003e dimensions. In this work, we propose a new FDT valid for the KPZ problem in \u003cinline-formula\u003e\u003cmath xmlns=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"\u003e\u003csemantics\u003e\u003cmrow\u003e\u003cmi\u003ed\u003c/mi\u003e\u003cmo\u003e+\u003c/mo\u003e\u003cmn\u003e1\u003c/mn\u003e\u003c/mrow\u003e\u003c/semantics\u003e\u003c/math\u003e\u003c/inline-formula\u003e dimensions. This is achieved by rearranging terms and identifying a new correlated noise which we argue to be characterized by a fractal dimension \u003cinline-formula\u003e\u003cmath xmlns=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"\u003e\u003csemantics\u003e\u003cmsub\u003e\u003cmi\u003ed\u003c/mi\u003e\u003cmi\u003en\u003c/mi\u003e\u003c/msub\u003e\u003c/semantics\u003e\u003c/math\u003e\u003c/inline-formula\u003e. We present relations between the KPZ exponents and two emergent fractal dimensions, namely \u003cinline-formula\u003e\u003cmath xmlns=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"\u003e\u003csemantics\u003e\u003cmsub\u003e\u003cmi\u003ed\u003c/mi\u003e\u003cmi\u003ef\u003c/mi\u003e\u003c/msub\u003e\u003c/semantics\u003e\u003c/math\u003e\u003c/inline-formula\u003e, of the rough interface, and \u003cinline-formula\u003e\u003cmath xmlns=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"\u003e\u003csemantics\u003e\u003cmsub\u003e\u003cmi\u003ed\u003c/mi\u003e\u003cmi\u003en\u003c/mi\u003e\u003c/msub\u003e\u003c/semantics\u003e\u003c/math\u003e\u003c/inline-formula\u003e. Also, we simulate KPZ growth to obtain values for transient versions of the roughness exponent \u003cinline-formula\u003e\u003cmath xmlns=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"\u003e\u003csemantics\u003e\u003cmi\u003eα\u003c/mi\u003e\u003c/semantics\u003e\u003c/math\u003e\u003c/inline-formula\u003e, the surface fractal dimension \u003cinline-formula\u003e\u003cmath xmlns=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"\u003e\u003csemantics\u003e\u003cmsub\u003e\u003cmi\u003ed\u003c/mi\u003e\u003cmi\u003ef\u003c/mi\u003e\u003c/msub\u003e\u003c/semantics\u003e\u003c/math\u003e\u003c/inline-formula\u003e and, through our relations, the noise fractal dimension \u003cinline-formula\u003e\u003cmath xmlns=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"\u003e\u003csemantics\u003e\u003cmsub\u003e\u003cmi\u003ed\u003c/mi\u003e\u003cmi\u003en\u003c/mi\u003e\u003c/msub\u003e\u003c/semantics\u003e\u003c/math\u003e\u003c/inline-formula\u003e. Our results indicate that KPZ may have at least two fractal dimensions and that, within this proposal, an FDT is restored. Finally, we provide new insights into the old question about the upper critical dimension of the KPZ universality class.","source":"DOAJ","year":2024,"language":"","subjects":["Science","Astrophysics","Physics"],"doi":"10.3390/e26030260","url":"https://www.mdpi.com/1099-4300/26/3/260","is_open_access":true,"published_at":"","score":68},{"id":"doaj_10.1140/epjc/s10052-024-12616-w","title":"Gravitationally induced unified relation among duality, coherence, steering, and maximal average fidelity","authors":[{"name":"Duo-Duo Chen"},{"name":"Dong-Dong Dong"},{"name":"Xue-Ke Song"},{"name":"Liu Ye"},{"name":"Dong Wang"}],"abstract":"Abstract Recently, numerous measures have been proposed for quantifying the quantumness of a given system, and the existence of intrinsic connections among quantum resource measures has been proven. Here, we study the unified relationship between duality, first-order coherence, three-setting linear steering inequality, and maximum average fidelity between two masses due to gravity. Under gravitational inducement, an equivalent relationship was identified between the first-order coherence and duality. The coherence of a system can be controlled by adjusting arm lengths and the distance between the arms of an interferometer. In most cases, the first-order coherence of a system cannot be maximised. Furthermore, a trade-off relationship between gravitationally induced duality and steering violations was derived. We can adjust the arm length and distance between the arms of the interferometer such that the steering violation reaches its maximum at phase $$\\pi $$ π . The results show that the value of the steering violation is always greater than 1; that is, the state of the system is steerable. In addition, we explored the intrinsic relationship between duality and the maximal average fidelity due to gravity. In most cases, the maximum average fidelity of the system is greater than 2/3, indicating that the state is useful for quantum teleportation. These results are important for investigating the intrinsic relationships among various quantum resources within the framework of gravity.","source":"DOAJ","year":2024,"language":"","subjects":["Astrophysics","Nuclear and particle physics. Atomic energy. Radioactivity"],"doi":"10.1140/epjc/s10052-024-12616-w","url":"https://doi.org/10.1140/epjc/s10052-024-12616-w","is_open_access":true,"published_at":"","score":68},{"id":"doaj_10.3390/e26110978","title":"Quantum Control Design by Lyapunov Trajectory Tracking and Optimal Control","authors":[{"name":"Hongli Yang"},{"name":"Guohui Yu"},{"name":"Ivan Ganchev Ivanov"}],"abstract":"In this paper, we investigate a Lyapunov trajectory tracking design method that incorporates a Schrödinger equation with a dipole subterm and polarizability. Our findings suggest that the proposed control law can overcome the limitations of certain existing control laws that do not converge. By integrating a quadratic performance index, we introduce an optimal control law, which we subsequently analyze for stability and optimality. We also simulate the spin-1/2 particle system to illustrate our results. These findings are further validated through numerical illustrations involving a 3D, 5D system, and a spin-1/2 particle system.","source":"DOAJ","year":2024,"language":"","subjects":["Science","Astrophysics","Physics"],"doi":"10.3390/e26110978","url":"https://www.mdpi.com/1099-4300/26/11/978","is_open_access":true,"published_at":"","score":68},{"id":"doaj_10.1140/epjc/s10052-024-13590-z","title":"Nonresonant renormalization scheme for twist-2 operators in SU(N) Yang–Mills theory","authors":[{"name":"Francesco Scardino"}],"abstract":"Abstract Recently, the short-distance asymptotics of the generating functional of n-point correlators of twist-2 operators in SU(N) Yang–Mills (YM) theory has been worked out in Bochicchio et al. (Phys Rev D 108:054023, 2023). The above computation relies on a basis change of renormalized twist-2 operators, where $$-\\gamma (g)/ \\beta (g)$$ - γ ( g ) / β ( g ) reduces to $$\\gamma _0/ (\\beta _0\\,g)$$ γ 0 / ( β 0 g ) to all orders of perturbation theory, with $$\\gamma _0$$ γ 0 diagonal, $$\\gamma (g) = \\gamma _0 g^2+\\cdots $$ γ ( g ) = γ 0 g 2 + ⋯ the anomalous-dimension matrix and $$\\beta (g) = -\\beta _0 g^3+\\cdots $$ β ( g ) = - β 0 g 3 + ⋯ the beta function. The construction is based on a novel geometric interpretation of operator mixing (Bochicchio in Eur Phys J C 81:749, 2021), under the assumption that the eigenvalues of the matrix $$\\gamma _0/ \\beta _0$$ γ 0 / β 0 satisfy the nonresonant condition $$\\lambda _i-\\lambda _j\\ne 2k$$ λ i - λ j ≠ 2 k , with $$\\lambda _i$$ λ i in nonincreasing order and $$k\\in {\\mathbb {N}}^+$$ k ∈ N + . The nonresonant condition has been numerically verified up to $$i,j=10^4$$ i , j = 10 4 in Bochicchio et al. (Phys Rev D 108:054023, 2023). In the present paper we provide a number theoretic proof of the nonresonant condition for twist-2 operators essentially based on the classic result that Harmonic numbers are not integers. Our proof in YM theory can be extended with minor modifications to twist-2 operators in $$\\mathcal {N}=1$$ N = 1 SUSY YM theory, large-N QCD with massless quarks and massless QCD-like theories.","source":"DOAJ","year":2024,"language":"","subjects":["Astrophysics","Nuclear and particle physics. Atomic energy. Radioactivity"],"doi":"10.1140/epjc/s10052-024-13590-z","url":"https://doi.org/10.1140/epjc/s10052-024-13590-z","is_open_access":true,"published_at":"","score":68},{"id":"arxiv_2304.13746","title":"IDEFIX: a versatile performance-portable Godunov code for astrophysical flows","authors":[{"name":"G. R. J. Lesur"},{"name":"S. Baghdadi"},{"name":"G. Wafflard-Fernandez"},{"name":"J. Mauxion"},{"name":"C. M. T. Robert"},{"name":"M. Van den Bossche"}],"abstract":"Exascale super-computers now becoming available rely on hybrid energy-efficient architectures that involve an accelerator such as Graphics Processing Units (GPU). Leveraging the computational power of these machines often means a significant rewrite of the numerical tools each time a new architecture becomes available. To address these issues, we present Idefix, a new code for astrophysical flows that relies on the Kokkos meta-programming library to guarantee performance portability on a wide variety of architectures while keeping the code as simple as possible for the user. Idefix is based on a Godunov finite-volume method that solves the non-relativistic HD and MHD equations on various grid geometries. Idefix includes a wide choice of solvers and several additional modules (constrained transport, orbital advection, non-ideal MHD) allowing users to address complex astrophysical problems. Idefix has been successfully tested on Intel and AMD CPUs (up to 131 072 CPU cores on Irene-Rome at TGCC) as well as NVidia and AMD GPUs (up to 1024 GPUs on Adastra at CINES). Idefix achieves more than 1e8 cell/s in MHD on a single NVidia V100 GPU and 3e11 cell/s on 256 Adastra nodes (1024 GPUs) with 95% parallelization efficiency (compared to a single node). For the same problem, Idefix is up to 6 times more energy efficient on GPUs compared to Intel Cascade Lake CPUs. Idefix is now a mature exascale-ready open-source code that can be used on a large variety of astrophysical and fluid dynamics applications.","source":"arXiv","year":2023,"language":"en","subjects":["astro-ph.IM","astro-ph.HE","astro-ph.SR"],"doi":"10.1051/0004-6361/202346005","url":"https://arxiv.org/abs/2304.13746","pdf_url":"https://arxiv.org/pdf/2304.13746","is_open_access":true,"published_at":"2023-04-26T18:00:01Z","score":67},{"id":"doaj_10.22034/ijism.2022.1977746.0","title":"Social Network Analysis of Editorial Board Interlocking Phenomena from the Perspective of Astronomy and Astrophysics Journals","authors":[{"name":"Farshid Danesh"},{"name":"Samaneh Kesht Karan"},{"name":"Lili Banihashemi"},{"name":"Somayeh GhaviDel"}],"abstract":"Editorial board members (EBMs) of journals play a pivotal role in authentic international scientific journals. Editorial Board Interlocking (EBI) phenomenon reflects the effectiveness and importance of the scholarly journal's editorial boards in various scientific fields. The primary purpose of this paper is to conduct a Social Network Analysis (SNA) of EBI phenomena from the perspective of astronomy and astrophysics journals. The present study is applied research based on EBI, SNA, and the descriptive-analytical approach. The statistical population of this study consists of the editorial board members of all journals of astronomy and astrophysics indexed in the JCR and official journal websites. There are 1597 job positions in 67 astronomy and astrophysics journals occupied by the 1394 scholars. Data analysis shows EBI for 95 scholars and 79 organizations. \"Aleksei A. Starobinsky\" from Russia and the Russian Academy of Sciences, \"Daniel J. Scheeres\" from the United States, and the University of Colorado Boulder have the highest EBI contributions in five journals. \"Daniel J. Scheeres,\" with a centrality of 39, has the highest degree of centrality measurement among the EBMs. The presence of more than five times as many men as women indicates that astronomy and astrophysics journals are considered \"masculine\" by the editorial board. The EBI phenomenon is observed in astronomy and astrophysics journals due to the limited number of peop le eligible for the editorial board. Due to EBI, a limited number of famous scholars are made macro-policies such as publishing the articles, referees selections, and the reviewing process. Astronomy and astrophysics journals have \"elite\" academic networks. Gender inequality exists among EBMs, and the majority of them are male. Accordingly, these journals are \"men's journals.\"","source":"DOAJ","year":2023,"language":"","subjects":["Information resources (General)","Transportation and communications"],"doi":"10.22034/ijism.2022.1977746.0","url":"https://ijism.ricest.ac.ir/article_700756_9208d514293adf1eaa17de5955477120.pdf","pdf_url":"https://ijism.ricest.ac.ir/article_700756_9208d514293adf1eaa17de5955477120.pdf","is_open_access":true,"published_at":"","score":67},{"id":"doaj_10.1029/2023GL104610","title":"Shocklets and Short Large Amplitude Magnetic Structures (SLAMS) in the High Mach Foreshock of Venus","authors":[{"name":"Glyn A. Collinson"},{"name":"Heli Hietala"},{"name":"Ferdinand Plaschke"},{"name":"Tomas Karlsson"},{"name":"Lynn B. Wilson III"},{"name":"Martin Archer"},{"name":"Markus Battarbee"},{"name":"Xochitl Blanco‐Cano"},{"name":"Cesar Bertucci"},{"name":"David Long"},{"name":"Merav Opher"},{"name":"Nick Sergis"},{"name":"Claire Gasque"},{"name":"Terry Liu"},{"name":"Savvas Raptis"},{"name":"Sofia Burne"},{"name":"Rudy Frahm"},{"name":"Tielong Zhang"},{"name":"Yoshifumi Futaana"}],"abstract":"Abstract Shocklets and short large‐amplitude magnetic structures (SLAMS) are steepened magnetic fluctuations commonly found in Earth's upstream foreshock. Here we present Venus Express observations from the 26th of February 2009 establishing their existence in the steady‐state foreshock of Venus, building on a past study which found SLAMS during a substantial disturbance of the induced magnetosphere. The Venusian structures were comparable to those reported near Earth. The 2 Shocklets had magnetic compression ratios of 1.23 and 1.34 with linear polarization in the spacecraft frame. The 3 SLAMS had ratios between 3.22 and 4.03, two of which with elliptical polarization in the spacecraft frame. Statistical analysis suggests SLAMS coincide with unusually high solar wind Alfvén mach‐number at Venus (12.5, this event). Thus, while we establish Shocklets and SLAMS can form in the stable Venusian foreshock, they may be rarer than at Earth. We estimate a lower limit of their occurrence rate of ≳14%.","source":"DOAJ","year":2023,"language":"","subjects":["Geophysics. Cosmic physics"],"doi":"10.1029/2023GL104610","url":"https://doi.org/10.1029/2023GL104610","is_open_access":true,"published_at":"","score":67},{"id":"doaj_10.3847/2041-8213/acab5d","title":"Evidence for Enrichment of Niobium-92 in the Outer Protosolar Disk","authors":[{"name":"Yuki Hibiya"},{"name":"Tsuyoshi Iizuka"},{"name":"Hatsuki Enomoto"},{"name":"Takehito Hayakawa"}],"abstract":"The short-lived radionuclide, niobium-92 ( ^92 Nb), has been used to estimate the site of nucleosynthesis for p- nuclei and the timing of planetary differentiation, assuming that it was uniformly distributed in the early solar system. Here, we present the internal niobium–zirconium (Nb–Zr) isochron dating of Northwest Africa (NWA) 6704, an achondrite thought to form in the outer protosolar disk due to nucleosynthetic isotope similarities with carbonaceous chondrites. The isochron defines an initial ^92 Nb/ ^93 Nb ratio of (2.72 ± 0.25) × 10 ^−5 at the NWA 6704 formation, 4562.76 ± 0.30 million years ago. This corresponds to a ^92 Nb/ ^93 Nb ratio of (2.96 ± 0.27) × 10 ^−5 at the time of solar system formation, which is ∼80% higher than the values obtained from meteorites formed in the inner disk. The results suggest that a significant proportion of the solar ^92 Nb was produced by a nearby core-collapse supernova (CCSN) and that the outer disk was more enriched in CCSN ejecta, which could account for the heterogeneity of short-lived ^26 Al and nucleosynthetic stable-isotope anomalies across the disk. We propose that NWA 6704 serves as the best anchor for mapping relative Nb–Zr ages of objects in the outer solar system onto the absolute timescale.","source":"DOAJ","year":2023,"language":"","subjects":["Astrophysics"],"doi":"10.3847/2041-8213/acab5d","url":"https://doi.org/10.3847/2041-8213/acab5d","is_open_access":true,"published_at":"","score":67}],"total":191106,"page":1,"page_size":20,"sources":["arXiv","DOAJ","CrossRef"],"query":"Astrophysics"}