High Energy Physics (Phenomenology)
Update of the Standard-Model prediction for $\bar B \to X_s \gamma$
Tobias Huber
We report on two recent calculations on the inclusive radiative decay $\bar B\to X_s \gamma$, notably multi-parton contributions at NLO and the $Q_{1,2}-Q_7$ interference at NNLO for the physical value of the charm-
quark mass. The former calculation formally completes $\bar{B} \rightarrow X_s \gamma$ at NLO in QCD at leading power, the latter removes a long-standing $\pm 3\%$ uncertainty arising from interpolation in $m_c$. The updated Standard-Model prediction for the CP- and isospin-averaged branching ratio reads ${\mathcal B}_{s \gamma}^{\rm SM} = (3.54 \pm 0.14)\times 10^{-4}$ for
photon energies $E_\gamma > 1.6\,{\rm GeV}$ in the $B$-
meson rest frame. This value is in good agreement with the current experimental average ${\mathcal B}_{s \gamma}^{\rm exp} = (3.49 \pm 0.19)\times 10^{-4}$.
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Cosmology and Nongalactic Astrophysics
A Class of Exact Single-Field Inflationary Solutions beyond Slow Roll
Jia-Wei Zhang, Bai-Cian Ke, Yao Yu et al. (+2 more)
We construct exact solutions for single-field inflaton dynamics without invoking the slow-roll approximation. A suitable change of variables reduces the background equation to an Abel equation of the first kind. Although a generic Abel equation is not analytically solvable, we identify a class of inflaton potentials for which the transformed equation admits exact solutions. The resulting framework contains constant-roll inflation as a special case and also accommodates solutions with a constant second Hubble-flow parameter. We analyze the linear local attractor behavior and superhorizon
evolution of these rolling backgrounds. Using the public joint CMB likelihood contours in the $(n_s,r)$ plane, we identify compatible parameter regions and show that one rolling branch can also yield $50\leq N_*<60$. Direct numerical
evolution of the scalar and tensor modes at representative points validates the local-index predictions to better than $7\times10^{-4}$ in $n_s$ and $2\times10^{-6}$ in $r$. The exact family extends beyond slow roll, although the observationally selected regions displayed here lie close to the slow-roll regime.
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All authors Jia-Wei Zhang, Bai-Cian Ke, Yao Yu, Dong-Ze He, Shou-Jia Wang
Materials Science
Numerical study of the grain-growth-induced non-parabolic kinetics of a solid-state reaction
Ya. A. Nikiforov, S. A. Chizhik and N. I. Baklanova
Non-
parabolic growth of reaction layers is frequently observed in solid-state
diffusion couples, but the relationship between microstructural
evolution and the resulting kinetics remains incompletely understood. This effect is commonly attributed to grain growth, which can progressively reduce the contribution of fast grain-boundary
diffusion, causing the effective diffusivity of a polycrystalline product layer to evolve during reaction. This work develops a moving-boundary
diffusion model to describe product-layer growth while accounting for the local grain-growth history of the continuously formed product, as well as both bulk and grain-boundary
diffusion. Numerical simulations show that the reaction can pass through three distinct kinetic regimes: an initial approximately
parabolic regime dominated by grain-boundary
diffusion, a transient sub-
parabolic regime associated with strong spatial variation of the effective diffusivity, and a subsequent approximately
parabolic regime dominated by bulk
diffusion. The magnitude and duration of the sub-
parabolic regime depend on the relative grain-boundary and bulk diffusivities and on the kinetics of grain growth. The instantaneous growth exponent therefore evolves continuously and does not represent a unique kinetic constant. Nevertheless, fitting simulated layer-thickness data over finite experimental time intervals produces well-defined apparent exponents, demonstrating how a transient process can appear to obey a single power law.
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High Energy Physics (Phenomenology)
NNLL fit of the transverse-momentum-dependent distribution of unpolarised gluons to LHCb data on $J/\psi$-pair production
D. Boer, J. Bor, A. C. Serri et al. (+4 more)
We perform the first fit of the unpolarised
gluon transverse-momentum-dependent distribution $f_1^g$ up to next-to-next-to-leading-logarithmic accuracy to the double-differential distribution in the invariant mass and transverse momentum of the latest $J/\psi$-pair production LHCb data. We review previous attempts to describe the older $J/\psi$-pair LHCb data using $f_1^g$, and discuss two novel methodologies which allow us to account in the fit for both the perturbative and PDF uncertainties to construct $f_1^g$ in the perturbative region. It turns out that the consideration of these uncertainties is crucial for a meaningful fit to such low-scale
gluon-sensitive data.
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All authors D. Boer, J. Bor, A. C. Serri, M. G. Echevarria, J. P. Lansberg, S. F. Romera, P. Taels
General Relativity and Quantum Cosmology
Dissipative Multi-Field Dynamics from Non-Hermitian Inflationary Potentials
S. D. Campos
In this work, we develop a perturbative framework for inflation driven by a complex inflaton with non-minimal gravitational coupling and a non-Hermitian potential. During the observable
cosmic microwave background radiation era, the dynamics reduce to an effectively conservative two-field model, preserving the predictions of the $\alpha$-attractor class and satisfying Planck 2018 and BICEP/Keck constraints on $n_s$, $r$, and $f_{\mathrm{NL}}$. Near the end of inflation, trajectory bending activates the non-Hermitian sector, triggering
geometric reheating. The resulting non-
unitary evolution modifies the
curvature spectrum and
stochastic gravitational-wave background through a calculable damping factor determined by the complex mass
eigenvalues. While
cosmic microwave background-scale observables remain essentially unchanged, a distinctive suppression emerges in the high-frequency gravitational-wave spectrum ($f > 10^2$ Hz), potentially testable by future detectors such as the Einstein
Telescope and the Big Bang Observer.
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Atomic Physics
Impact of light shift inhomogeneities on the contrast of light pulse atom interferometers
Maxime Pesche, Diego Lancheros Naranjo, Rayan Si-Ahmed et al. (+3 more)
We study the loss of the contrast in an atom interferometer when increasing the duration of Raman mirror pulses, and find the contrast decay rate to increase with the interferometer duration. We attribute this effect to the transverse spatial fluctuations of the intensity across the Raman beams, and to the dephasing induced by the associated light shifts inhomogeneities. Simulations based on the propagation of noisy synthetic Raman beams show that the contrast decay rate increases with the distance between the wavepackets at the mirror pulse, before reaching an asymptotic limit when intensity fluctuations between the two wavepackets become completely decorrelated. Finally, simulations based on the propagation of Raman beams having their measured intensity fluctuations predict contrast loss rates consistent with our measurements, confirming the detrimental role for the interferometer contrast played by intensity fluctuations across the interferometer
laser beams.
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All authors Maxime Pesche, Diego Lancheros Naranjo, Rayan Si-Ahmed, Gabriel Ducasse, Franck Pereira dos Santos, Sébastien Merlet
High Energy Astrophysical Phenomena
A Galactic microblazar as a potential accelerator of ultra-high-energy particles
Josep Martí, Pedro L. Luque-Escamilla, Benito Marcote et al. (+10 more)
Context. Persistent jets from X-ray binaries which are aligned very close to the line of sight could be considered to be
Galactic equivalents of blazars, or 'microblazars'. They are also expected to power gamma-ray sources. Aims. We intend to assess a serious candidate apparently fulfilling many of the requirements to be considered a genuine member of this class: IRAS 18293-0941. Methods. An intense multi-wavelength observational and theoretical study has been carried out on our proposed candidate source. Results. With photometric and spectroscopic properties typical of a binary
star, this system exhibits clear collimated and one-sided
radio emission matching the effects of relativistic motion along a reduced ejection angle. Only fast variability is not observed possibly smoothed by a dense circumstellar envelope. A physical scenario is consistently modeled that also gives credibility to its likely connection with LHAASO J1831-1007u*, an ultra-high-energy source in its immediate vicinity. Conclusions. Our reported identification not only helps to fill a gap in
Galactic taxonomy, but also potentially strengthens the role of the microblazar and microquasar families in our understanding of the most energetic Milky Way phenomena.
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All authors Josep Martí, Pedro L. Luque-Escamilla, Benito Marcote, Leandro Abaroa, Arnau Aguasca-Cabot, Jorge A. Combi, Gustavo E. Romero, Josep M. Paredes, Federico García, Federico Fogantini, Enzo A. Saavedra, Daniel del Ser, Jakob van den Eijnden
High Energy Astrophysical Phenomena
The Missing MeV Window for Identifying Galactic PeVatrons: the need for a dedicated MeV Observatory
Martina Cardillo, Riccardo Campana, Yuri Evangelista et al. (+1 more)
The identification of the sources responsible for accelerating
Galactic cosmic-rays up to PeV energies remains a major open question in high-energy astrophysics. Recent observations by the Large High Altitude Air Shower Observatory (LHAASO) have revealed a growing population of
Galactic PeVatron candidates. However, the detection of TeV-PeV gamma-rays alone does not uniquely identify the nature of the emitting particles. In many cases, both hadronic and leptonic scenarios can reproduce the observed very-high-energy emission, leaving the origin of the radiation unresolved. The most robust and least model-dependent electromagnetic tracer of hadronic acceleration is provided by neutral-pion decay, which produces the characteristic pion bump in the 10-100 MeV energy range. Observations in this energy band are therefore essential to establish whether candidate PeVatrons are accelerating
protons and
nuclei and, consequently, to assess their role in the origin of
Galactic cosmic-rays. More broadly, the MeV domain addresses key astrophysical questions, but remains one of the least explored regions of the electromagnetic spectrum. As current and future VHE facilities expand the
Galactic PeVatron census, the lack of MeV observations is becoming a major limitation for source identification. We discuss the astrophysical science drivers and observational requirements for a dedicated MeV gamma-ray capability optimized for pion-bump studies. We explore the concept of a compact, focused, and potentially fast-track mission capable of filling the impending MeV observational gap while more ambitious next-generation MeV facilities are developed and evaluated. Such a mission would provide the missing diagnostic needed to distinguish hadronic and leptonic emission, identify
Galactic cosmic-ray accelerators, and fully exploit the scientific return of the emerging generation of TeV observatories.
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All authors Martina Cardillo, Riccardo Campana, Yuri Evangelista, Fabio Muleri
High Energy Physics (Phenomenology)
Amplitude structure of $3\to 3$ scattering in a Mandelstam variable representation
Xu Zhang and Feng-Kun Guo
We construct a dispersive representation of the relativistic $3\to 3$ scattering amplitude for three identical spinless particles in the $S$-wave. The two-particle subenergy, instead of the total energy, is used as the dispersive variable. This choice keeps the physical dispersive contour free of the kinematical cuts that complicate total-energy dispersion relations. By separating discontinuities across the two-particle subenergy cuts from that across the three-body cut, we derive a linear integral equation with one-particle exchange as the driving term. We further show that the solution satisfies three-body unitarity as a consequence of two-body unitarity, analyticity, and crossing
symmetry. For pair-wise interactions, this representation can be rewritten into the form used for isobar-spectator scattering. Finally, we give prescriptions for contour deformation and the subtraction of poles in the two-body subsystem amplitudes, which continue the amplitude onto adjacent unphysical Riemann sheets and thus provide direct access to the analytic structure relevant for three-body resonance poles.
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Chaotic Dynamics
Predicting Phase Ordering in Chaotic Maps and Coupled Map Lattices
Shiva Dixit, Swati Chauhan and Manish Dev Shrimali
Coupled logistic maps exhibit collective ordering of their directional phases. As the system parameter varies, the directional phases can undergo a transition from an in-phase state to an anti-phase state, while the individual map trajectories remain chaotic. In this work, we propose a data-driven machine learning (ML) framework based on parameter-aware reservoir computing (PARC) to predict order-parameter dynamics in two representative systems: a logistic map and a two-dimensional coupled map
lattice (CML). For the logistic map, the reservoir is trained using only pre-crisis time series data at bifurcation parameter $\mu$ values below the attractor-merging crisis ($\mu_0 = 3.6786$). The trained reservoir reconstructs the full bifurcation diagram and correctly predicts the transition in the directional order parameter $M(\mu)$, from an ordered state ($M \approx 0$) to a disordered state ($M \neq 0$) across the crisis point. For the CML, we exploit the spatial homogeneity of the
lattice: a single reservoir is trained on the dynamics of one representative
lattice site and is then replicated across all $L^2$ sites during prediction, where $L$=50. The replicated reservoir correctly predicts the transition from in-phase synchronization ($\theta \approx 1$) to anti-phase clustered states ($\theta \approx 0$) at $\mu \approx 3.82$, where $\theta$ quantifies phase coherence across
lattice sites.
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General Relativity and Quantum Cosmology
Near-extremal asymptotics and strong cosmic censorship for black holes immersed in a Chaplygin-like dark fluid
Hao-Peng Yan, Zeng-Yi Zhang, Xiang-Qian Li et al. (+1 more)
We investigate strong
cosmic censorship (SCC) for massless scalar perturbations of electrically neutral black holes immersed in a Chaplygin-like dark fluid (CDF). The matter distribution produces an asymptotically de Sitter exterior while supporting an inner Cauchy horizon. We derive a closed-form parametrization of the extremal and Nariai horizon boundaries. This analytic control yields explicit near-extremal asymptotics for the horizon splitting and Cauchy-horizon surface
gravity, together with an analytic expression for the leading near-extremal scalar quasinormal spectrum. The fundamental near-extremal damping rate approaches the Cauchy-horizon surface
gravity, whereas higher angular multipoles retain explicit dependence on the CDF extremal geometry. Combining these analytic results with global quasinormal-mode calculations, we determine the spectral gap and assess the Christodoulou formulation of SCC throughout the three-horizon domain. Potential SCC violation is confined to a narrow region near extremality. As the effective cosmological scale increases, the lower boundary of this region is controlled successively by de Sitter,
photon-sphere, and de Sitter modes, while its normalized width varies nonmonotonically.
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All authors Hao-Peng Yan, Zeng-Yi Zhang, Xiang-Qian Li, Xiao-Jun Yue
Optics
Topological charge switching in trapped polariton condensates
Jaewon Kim, Hyun Gyu Song, Daegwang Choi et al. (+1 more)
Topological charges in photonic systems provide a robust degree of freedom with direct applications in optical information processing. Bound states in the continuum (BICs) in photonic
crystal slabs inherently carry such quantized topological charges, yet they are topologically protected, making active reconfiguration fundamentally challenging. Here, we demonstrate topological charge switching in trapped BIC polariton condensates in a photonic
crystal, where spatial modulation of the photonic
crystals supports multiple confined states, each carrying a distinct charge. Trapped condensates within the Dirac bandgap are expelled into the leaky band via polariton blueshift, enabling single-mode selection by solely tuning the excitation power. This work offers a platform for optically controlling topological charges by harnessing polariton nonlinearity.
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All authors Jaewon Kim, Hyun Gyu Song, Daegwang Choi, Yong-Hoon Cho
Quantum Physics
Information geometry of non-equilibrium quantum states: Mixed metric structures on an extended information manifold
Kouji Kashiwa and Hidefumi Matsuda
We discuss an information-
geometric framework for characterizing
quantum states in non-
equilibrium dynamics. Using the transverse-field Ising chain model as a laboratory, we investigate the
quantum Fisher information metric with particular emphasis on the mixed metric component $g_{ht}$ and related
geometric observables, where $h$ is a controllable post-quench
Hamiltonian parameter and $t$ is real time. The framework treats $h$ and $t$ as coordinates of an extended information
manifold $(h,t)$. The
geometric observables characterize the speed of
evolution on the
manifold and the
alignment between the temporal and parameter-deformation directions. Correlations between these
geometric quantities and two widely used measures of non-
equilibrium dynamics, the
entanglement entropy and the Loschmidt echo, are analyzed.
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High Energy Physics (Theory) · Cross-listed from math.GT
Lipshitz-Sarkar refines mirrors more than Khovanov
Yang-Hui He
Lipshitz and Sarkar asked in an ICM 2018 question whether their homotopy-theoretic refinement of Khovanov homology can detect mirror reflection when ordinary integral Khovanov homology cannot. We give an affirmative answer by presenting a
prime knot whose integral Khovanov homology agrees with that of its mirror in every bidegree, including torsion, and yet over $\mathbb{F}_2$, the second Steenrod square has rank one for the
knot and rank zero for its mirror in a specified bidegree. We also give a composite example. The construction, search and computations are done with the help of chat-GTP 5.6 sol Pro combing over the Regina Census of
knots.
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Mesoscale and Nanoscale Physics
Topological charges and parity selection at Floquet quasienergy degeneracies
Sigmund Kohler and David Guéry-Odelin
The quasienergy spectrum of a strongly driven two-level system as a function of the driving parameters exhibits conical intersections, which are enabled by hidden time-nonlocal
symmetries. We show that each such crossing carries a quantized topological charge: the Floquet–Berry phase acquired along an adiabatic loop around a cone is equal to a $\mathbb{Z}_2$-valued charge. We further identify a second family of degeneracies that occurs at vanishing driving amplitude, when the level splitting matches $m$ energy quanta of the field. Along the Stark-shifted resonance line, the minimum quasienergy gap opens as $|A|^m$, and the charge is nontrivial only for odd $m$. We analytically derive both results from a perturbative reduction to a
spin-$1/2$ in an effective two-dimensional
magnetic field and confirm them numerically through the Bargmann invariant. Moreover, we propose a chirality-based protocol that cancels the dynamical phase to isolate the
geometric one, and an ancilla-based Ramsey readout that renders the topological charge directly observable.
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Instrumentation and Detectors
Time performance of USTC-IME LGAD under synchrotron light source focused X-ray
Tianao Wang, De Zhang, Zheng Liang et al. (+9 more)
The time performance of Low Gain Avalanche Diodes (LGADs), designed by the University of Science and Technology of China (USTC) and fabricated by the Institute of Microelectronics of Chinese Academy of Sciences (IME), was characterized at the Shanghai Synchrotron Radiation Facility (SSRF). The experiment was conducted at the BL16B1 beamline, which delivers a focused X-ray beam with a diameter of 500 \textmu\text{m}, a repetition period of 2 ns, and a
photon energy of 10 keV. Using a fast oscilloscope, waveforms containing continuous signal pulses were recorded within a 50 ns time window. The LGAD under test successfully resolved the 2 ns period of the SSRF. To mitigate pile-up effects and extract pulse-by-pulse information from the acquired waveforms, a waveform-level global template fitting method was employed. The time resolution was then estimated using a combined profile likelihood approach, with a restricted maximum-likelihood (REML) correction accounting for the per-waveform degrees of freedom, yielding a value of 136.8 $\pm$ 0.15 (stat.) $\pm$ 11.9 (syst.) ps. The complete reconstruction and fitting chain was validated end-to-end using simulated waveforms in which the timing deviations of individual large pulses were drawn from Gaussian distributions with fixed standard deviations. The effect of random
photon absorption depth on the time resolution of LGADs was studied through dedicated simulations.
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All authors Tianao Wang, De Zhang, Zheng Liang, Chaozhi Li, Jiaqi Luo, Yu Nie, Tianshuo Yue, Zebo Tang, Hao Liang, Tongpu Yu, Wanbing He, Yanwen Liu
Statistical Mechanics
Kibble–Zurek Mechanism and Defect Freezing in Imbalanced-Pairing Kitaev Models
R. Jafari, Alireza Akbari, Shukhrat Mardonov et al. (+1 more)
We investigate driven dynamics across critical and exceptional points in the one- and two-dimensional imbalanced-pairing Kitaev models using both the wave-function normalization approach and the biorthogonal framework. For a positive pairing imbalance parameter, the quasiparticle spectrum remains real, and a pairing imbalance neither shifts the
equilibrium phase boundaries nor generates imaginary eigenenergies. In this regime, the defect density follows the conventional Kibble–Zurek scaling in one dimension and the extended Kibble–Zurek scaling, arising from a gapless
manifold, in two dimensions within both frameworks. The corresponding scaling exponents are therefore governed by those of the Hermitian transition. For a negative pairing imbalance parameter, time-reversal
symmetry is broken, the quasiparticle spectrum develops complex
eigenvalues, and the gap closes at exceptional points. For ramps ending at an exceptional point, the defect density follows the modified Kibble–Zurek scaling in the wave-function normalization approach, whereas it obeys the conventional Kibble–Zurek scaling in the biorthogonal framework. When the ramp traverses the time-reversal-
symmetry-broken region, a finite density of defects remains even in the adiabatic limit, leading to defect freezing in both frameworks. Although this frozen background indicates a breakdown of adiabaticity, the excess defects generated on top of this background continue to obey the conventional Kibble–Zurek scaling in one dimension and the extended Kibble–Zurek scaling in two dimensions.
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All authors R. Jafari, Alireza Akbari, Shukhrat Mardonov, A. Langari
High Energy Astrophysical Phenomena
The Radius of the Neutron Star PSR J0614-3329 from NICER Data
M. C. Miller, A. J. Dittmann, I. M. Holt et al. (+14 more)
Neutron star radius measurements, particularly using X-ray data collected with the
Neutron star Interior Composition Explorer (NICER), have provided invaluable information for models of cold, catalyzed matter at densities above that of
nuclear saturation. Here we present an analysis of NICER data on the 318-Hz
pulsar PSR J0614-3329, which has a mass ~1.4-1.5
solar masses determined from
radio observations. The best-fitting model we explore has three uniform-temperature circular hot spots and yields a symmetric 68% credible range for the equatorial circumferential radius of 9.88-12.77 km. We also explore joint fits to the NICER data and the X-ray Multi-Mirror (XMM-Newton) data on this
pulsar, but find that the models that best fit both data sets systematically underpredict the XMM-Newton data when, as is standard, it is assumed that the XMM-Newton background is known from observations of surrounding fields. Finally, we discuss the implications of our results, combined with data on other
neutron stars, for the properties of the dense matter in
neutron star cores.
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All authors M. C. Miller, A. J. Dittmann, I. M. Holt, F. K. Lamb, C. Chirenti, Z. Arzoumanian, J. Berteaud, S. Bogdanov, K. C. Gendreau, A. K. Harding, W. C. G. Ho, C. Kalapotharakos, S. M. Morsink, P. S. Ray, R. A. Remillard, Z. Wadiasingh, M. T. Wolff
Superconductivity
Resolving unconventional gap structure in kagome superconductors with hybrid microwave circuits
Yejin Lee, Haolin Jin, Sushmita Chandra et al. (+12 more)
Unconventional superconductivity is a hallmark of exotic
quantum matter, where determining the pairing
symmetry is essential for uncovering its microscopic origin. Kagome
superconductors provide a fertile landscape for emergent phenomena arising from strong electronic correlations and nontrivial band
topology, yet their superconducting pairing
symmetry remains elusive. The superconducting gap structure is commonly probed via electrodynamic response, but such measurements are inapplicable to thin flakes due to their small volume and delicate nature. Superconducting microwave resonators offer a coherent and highly sensitive platform for probing electrodynamic responses, with versatile designs that enable incorporation of diverse materials and geometries. Here, we integrate flakes into microwave
circuits, enabling noninvasive access to the superfluid response through contactless coupling that preserves structural integrity. By engineering the device geometry to suppress parasitic two-level-system losses that dominate dissipation in microwave
circuits, we isolate the intrinsic material response. Remarkably, the temperature-dependent superfluid density exhibits linear behavior at low temperatures, consistent with a nodal gap structure. Our approach establishes a noninvasive platform for probing electrodynamic response of fragile superconducting flakes while advancing hybrid microwave architectures for
quantum technologies.
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All authors Yejin Lee, Haolin Jin, Sushmita Chandra, Berit H. Goodge, Edouard Lesne, Tommaso Confalone, Francesco Tafuri, Davide Massarotti, Golam Haider, Kornelius Nielsch, Bernd Büchner, Claudia Felser, Debanjan Chowdhury, Nicola Poccia, Uri Vool
High Energy Astrophysical Phenomena
Connecting radio pulsars, magnetars, and XDINSs in a unified evolutionary framework using simulation-based inference
Michele Ronchi, Celsa Pardo-Araujo, Vanessa Graber et al. (+7 more)
Understanding the
Galactic population of isolated
neutron stars within a unified framework provides key insights into their birth properties, evolutionary pathways, and the connections between different
neutron star classes. In this work, we aim to reproduce both the observed
radio and quiescent X-ray emission from isolated
neutron stars, including
radio pulsars, magnetars and X-ray dim isolated
neutron stars (XDINSs). We develop a comprehensive population synthesis framework that models
neutron star birth properties, their dynamical, rotational, and magneto-thermal
evolution, as well as
radio and X-ray emission, and the selection effects of corresponding surveys. To simulate realistic X-ray spectra, we account for magnetospheric resonant cyclotron scattering and interstellar absorption. Additionally, we model the observational bias introduced by magnetar outbursts, by linking the outburst rate to
magnetic stresses in the
stellar crust. We then employ a simulation-based inference method, namely truncated sequential neural posterior estimation, to reconstruct the birth properties, such as the initial
magnetic field distribution. We find that the
Galactic neutron star population can be described by a two-component log-normal distribution of birth
magnetic fields with peaks at $5 \times 10^{12}$ G and $10^{14}$ G, respectively. We further find that the
Galactic neutron star birth rate is around 3-4 per century. Our results help establish the contribution of
neutron stars as central engines of powerful astrophysical transient phenomena, such as fast
radio bursts, super-luminous
supernovae and gamma ray bursts.
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All authors Michele Ronchi, Celsa Pardo-Araujo, Vanessa Graber, Nanda Rea, Clara Dehman, Davide De Grandis, Alessio Marino, Francesco Coti Zelati, Joeri van Leeuwen, José A. Pons
Materials Science
Weisfeiler-Lehman subtree encoding for Bayesian optimization of atomic configurations
Akira Kusaba, Tatoshi Yonemori, Tetsuji Kuboyama et al. (+1 more)
The efficiency of
Bayesian optimization (BO) of atomic configurations depends strongly on how configurations are encoded. We introduce the Weisfeiler-Lehman (WL) subtree kernel, which views configurations as element-labeled graphs and measures their similarity by how many local structural patterns they share, into
Bayesian-optimization-based configuration search. Because this kernel is reproduced as the plain inner product of explicit features (L$^2$-normalized histograms of local topological patterns), introducing it reduces to introducing the corresponding features: the encoding enters existing BO frameworks as an ordinary descriptor. In a
benchmark ground-state configuration search of cubic BC$_2$N evaluated with a universal machine-learning interatomic potential, the WL encoding reached the ground state almost immediately after a shared random initialization of 100 samples in every one of five independent rounds (108$\pm$5 evaluations on average), whereas the one-hot baseline required 280$\pm$122 evaluations; the WL-driven sampler first exhausted the degenerate ground-state group and then discovered the metastable degenerate groups from the bottom up, in order of increasing energy.
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All authors Akira Kusaba, Tatoshi Yonemori, Tetsuji Kuboyama, Yoshihiro Kangawa
General Relativity and Quantum Cosmology
Constraining AGN Disk Properties with Gravitational Waves from Inspiraling Stellar-Mass Binary Black Holes in Hierarchical Triple Systems
Jie Wu, Mengfei Sun, Jin Li et al. (+1 more)
Space-based gravitational-wave detectors can observe
stellar-mass binary black holes (BBHs) long before merger, allowing weak environmental perturbations to accumulate. For binaries embedded in active
galactic nucleus (AGN) disks, the local gas density characterizes the environment of the supermassive black hole (SMBH) and compact-object migration. We study whether such signals can constrain this density when a
stellar-mass BBH orbits a Kerr SMBH. We evolve the outer orbit with relativistic corrections and gaseous dynamical friction (DF), and construct the detector-frame waveform including BBH inspiral, de Sitter precession, DF phase correction, and moving-source effects. Using Fisher-
matrix calculations for sampled systems, we estimate statistical uncertainties and systematic errors. Larger gas densities generally improve the statistical precision of several source and outer-orbit parameters, but also increase systematic errors when DF is omitted. For favorable GW190521-like systems observed by LISA for one year, the disk density can be constrained at the level of $\sigma_{\rho}\sim10^{-12}\text{--}10^{-10}\,{\rm g\,cm^{-3}}$. Such constraints would connect BBH merger environments to the gas structure of
galactic nuclei and the conditions that support black hole growth. These results indicate that hierarchical BBH inspirals can probe AGN disk environments, provided that gas effects are modeled consistently.
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All authors Jie Wu, Mengfei Sun, Jin Li, Zhoujian Cao
High Energy Physics (Theory)
Fuchsian Resonance and a Horizon-to-Boundary Dictionary for Pole-Skipping
Yoon-Seok Choun
Pole-skipping occurs at special complex frequencies and momenta where the retarded Green function of a black-hole or black-brane background is not uniquely defined. The local near-horizon mechanism is well known: at resonance, a Frobenius recurrence
matrix loses rank and the space of smooth horizon solutions enlarges. We address the global question of how two boundary-normalized solutions enter this resonant horizon solution space. For a general second-order scalar radial equation on a nonextremal background analytic near the horizon, the Frobenius recurrence at the resonant order yields a solvability condition. We prove that its vanishing is equivalent to singularity of the horizon recurrence
matrix, absence of the logarithmic Frobenius term, and existence of two independent smooth horizon solutions. Away from resonance, the source zero is equivalent to horizon smoothness of the response-normalized solution, while the response zero is equivalent to horizon smoothness of the source-normalized solution. We then analyze the parameter-dependent simple pole of the nonresonant ingoing solution as resonance is approached. After removing this singularity, its resonant limit is proportional to the larger-root Frobenius solution, with proportionality factor given by the same solvability function. Continuing to the boundary shows that the same condition is equivalent to simultaneous vanishing of the two regularized boundary connection coefficients. This establishes a horizon-to-boundary dictionary between local Fuchsian resonance and the boundary source-response 0/0 structure of pole-skipping. Finally, different directions of approach can select different resonant solutions, with the selection governed by the first parameter variation of the same solvability function.
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Quantum Physics
Robust CZ gate against flux line memory
Yao Song and Xiu-Hao Deng
High-fidelity CZ gates are central to superconducting
quantum processors, but implementations based on flux tuning are still sensitive to pulse distortion. Conventional predistortion, typically used for an isolated gate, can recover the desired flux at the chip but it fails if the flux line
memory exists, causing the fidelity of repeated CZ gates to drop rapidly. To address this issue, we model the flux line distortion as the dynamics of a stateful classical actuator coupled to a
quantum system. Using a first-order Dyson expansion, we derive the error generators induced by variations in the initial flux-line state. We then design a robust CZ gate by optimizing the flux pulse to suppress these generators and minimize the residual flux line state at the gate exit. A one-pole flux line model shows the expected first-order robustness plateau. For a more practical three-pole model, the optimized CZ pulse achieves $F_{\mathrm{avg}}=99.998\%$, suppresses all first-order error generators, and brings the residual flux line state close to zero. With no additional waiting time between gates, our robust pulse achieves $F_{\mathrm{avg}}=99.97\%$ for the complete ten-gate sequence and reduces the sequence infidelity by a factor of about $2.3\times10^{3}$ relative to the baseline under the same predistortion protocol. These results show that explicitly accounting for flux line
memory maintains high-fidelity CZ operation across repeated gate sequences and addresses a key limitation of conventional predistortion.
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Solar and Stellar Astrophysics
X-shooter survey Across Regions and Ages to probe Disk Evolution (ARADE): Accretion properties in Orion A and their relation with disk masses
Lara Piscarreta, Giacomo Beccari, Carlo Manara et al. (+10 more)
We present a homogeneous VLT/X-Shooter study of
accretion in young
stellar objects spanning the entire Orion A complex. Our sample includes 91 pre-main-sequence
stars hosting a protoplanetary disk according to Spitzer photometry, of which 34 have complementary ALMA
dust mass measurements. We derived
stellar and
accretion properties using a self-consistent multi-component fitting procedure. Our sample encompasses spectral types from K3 down to M5, corresponding to
stellar masses within $\sim$0.8-0.1 $M_{\odot}$. The
accretion-
stellar luminosity ($L_{acc}-L_{\star}$) and the mass
accretion rate-
stellar mass ($\dot{M}_{acc}-M_{\star}$) scaling relations in Orion A are consistent with those of other
star-forming regions (SFRs) that span a range of
stellar densities, far-ultraviolet (FUV) irradiation fields, and ages, with all regions occupying the same locus in parameter space. For the 34 sources with complementary
dust mass measurements, we present the first investigation of the $\dot{M}_{acc}$ and disk mass ($M_{disk}$) correlation in Orion A, recovering a spread consistent with that reported for other regions. Despite our sample spanning nearly five orders of magnitude in local FUV field strength, we find no statistically significant correlation between $\dot{M}_{acc}$ and FUV irradiation. However, by combining our sample with literature measurements in Lupus, the Orion Nebula Cluster, and $\sigma$ Orionis, we find a tentative population-level decrease of the inferred disk lifetime $t_{\rm disk} =M_{disk}/\dot{M}_{acc}$ toward stronger FUV environments, though large intrinsic scatter and limited sample sizes at intermediate and high FUV fields prevent firm conclusions. The homogeneous $\dot{M}_{acc}$ measurements reported here provide a solid foundation for future studies of
accretion and disk
evolution across the diverse environments of Orion A and other SFRs.
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All authors Lara Piscarreta, Giacomo Beccari, Carlo Manara, Rossella Anania, Sierk van Terwisga, Victor Almendros-Abad, Henri Boffin, Rik Claes, Aaron Empey, Barbara Ercolano, Tereza Jerabkova, Karina Maucó, Miguel Vioque
General Relativity and Quantum Cosmology
Polarization Images of Neutron Stars Illuminated by a Thin Accretion Disk: A Comparison with Black Holes
Dan-Dan Feng, Guo-Ping Li, Chen-Yu Yang et al. (+1 more)
We investigate linear polarization images of static, spherically symmetric
neutron stars illuminated by a geometrically and optically thin
accretion disk.
Neutron star equilibrium configurations are constructed with a polytropic equation of state, and the null geodesic equations and the parallel transport equation for the linear polarization vector are solved in the
geometric optics approximation. The numerical results show that the total polarized intensity is generally positively correlated with the total intensity and reaches its maximum near the
neutron star surface. As the observer inclination increases, the
symmetry of the polarization images is progressively broken. In addition, the
magnetic field configuration mainly affects the direction of the polarization vectors, while its influence on the overall polarized intensity distribution is comparatively limited. To further characterize the spatial structure of the polarization direction, we introduce the net electric vector position angle $\chi_{\mathrm{net}}$ and the second azimuthal
Fourier mode $\angle\beta_2$. A comparison with polarization images of a Schwarzschild black hole reveals clear differences between the two types of compact objects in the locations of strongly polarized regions and the size of the central region without a polarization signal. These results show that linear polarization images provide information beyond total intensity images for distinguishing
neutron stars from black holes.
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All authors Dan-Dan Feng, Guo-Ping Li, Chen-Yu Yang, Hong Lei
Cellular Automata and Lattice Gases
Optical free space extreme learning machine for the implementation of emergent complex systems
Elena Moreno, Fernando Soldevila and Daniel Torrent
Cellular automata conform a set of computational models which evolve with a reduced set of simple rules, yet still are able to show extremely complex emergent phenomena such as fractals and universal computation. Despite their apparent simplicity, they have shown great potential in simulating natural systems and solving challenging computational tasks such as classification and image generation. Instead of implementing cellular automata purely at the software level, it is desirable to design novel analog computing platforms that physically evolve following the automata's underlying rules, thereby reducing power requirements and latency. Here, we introduce an optical extreme learning machine for the simulation of a wide range of cellular automata. Our system operates in free space, and uses a spatial light modulator to encode the
evolution rules of the system, while coherent wave propagation performs the corresponding computations. Our results demonstrate a simple, fully-programmable, cost and power efficient, and easy to build and align platform for the implementation of a wide range of complex computational systems such as elementary cellular automata, Conway's Game of Life, and two-dimensional Turing machines.
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High Energy Physics (Phenomenology)
Investigating three-body resonances in $\alpha\alpha\Omega/\Omega_{ccc}$ clusters within the $^{9}_{\Omega/\Omega_{ccc}}{\mathrm{Be}}$ nucleus
Hao Zhou and Xiang Liu
We investigate the bound and resonant states of the $\alpha+\alpha+\Omega$ and $\alpha+\alpha+\Omega_{ccc}$ three-body systems, corresponding to $^{9}_{\Omega}{\mathrm{Be}}$ and $^{9}_{\Omega_{ccc}}{\mathrm{Be}}$, within the Gaussian expansion method combined with the complex scaling method. The $\alpha\Omega$ and $\alpha\Omega_{ccc}$ interactions are constructed by folding the $N\Omega$ and $N\Omega_{ccc}$ potentials obtained from
lattice QCD calculations by the HAL QCD Collaboration with the nucleon density distribution of the $\alpha$ particle. The uncertainty associated with the $\alpha$-particle matter radius is also examined. For the $\Omega$ sector, the strong $N\Omega$ attraction generates deeply bound $0_1^+$, $2_1^+$, and $4_1^+$ states in $^{9}_{\Omega}{\mathrm{Be}}$, accompanied by a pronounced contraction of the $\alpha\alpha$ core, demonstrating a strong gluelike effect of the $\Omega$
baryon. An unconventional inversion between the $0_1^+$ and $4_1^+$ levels is also predicted. In contrast, the $\Omega_{ccc}$
baryon produces considerably weaker attraction: the $0_1^+$ state of $^{9}_{\Omega_{ccc}}{\mathrm{Be}}$ is weakly bound, whereas the $2_1^+$ and $4_1^+$ states remain resonances. Their resonance energies and widths exhibit a clear dependence on the strength of the $\alpha\Omega_{ccc}$ interaction. These results reveal qualitatively different gluelike behaviors of the $\Omega$ and $\Omega_{ccc}$
baryons and provide predictions for the spectroscopy of exotic multistrange and triply charmed hypernuclei.
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Materials Science
Beyond Panchromatic Absorption: Deciphering the Excited-State Maze from Light Absorption to Photocatalysis in Dye-Sensitized MOFs
Manuela L. Kim, Mauricio E. Calvo, Katsuya Teshima et al. (+2 more)
Metal–organic frameworks (MOFs) are promising photocatalysts whose visible-light absorption can be extended through linker functionalization; however, a red-shifted absorption edge does not guarantee enhanced efficiency. Here, we establish a multi-spectroscopic framework to decipher the photophysical fate of photoexcited states in diazo-sensitized UiO-66 using 2D photoluminescence (PL/PLE) mapping and wavelength-resolved continuous-wave X-band photo-EPR. By correlating visible absorption with photo-EPR and PLE action spectra, we distinguish a productive red shift from a non-productive emissive red shift. In highly active UiO-66-Anisole (97% activity relative to \ch{TiO2}), photo-EPR tracks the new absorption band, confirming that excitation populates a charge-transfer pathway yielding persistent,
spin-separated states. Conversely, poorly active UiO-66-$\beta$-naphthol (4%) exhibits an extended visible absorption tracked by PLE but not photo-EPR. This reflects excitation trapping in a localized state caused by an ortho-$\mathrm{OH}$ group forming a rigid intramolecular hydrogen bond, which locks the keto-hydrazone tautomer and disrupts the conjugated azo bridge. A new optical overlap descriptor ($S_{\mathrm{Exc}}$) quantitatively captures this trade-off across the series. We demonstrate that photosensitizer design must suppress rigid tautomeric traps and target specific charge-transfer
manifolds ($\lambda \le 500$~nm) rather than merely maximizing apparent panchromatic absorption breadth.
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All authors Manuela L. Kim, Mauricio E. Calvo, Katsuya Teshima, Fabio La Mattina, Eugenio H. Otal
Solar and Stellar Astrophysics
Kinematic Relationship Between Solar Extreme Ultraviolet Waves and Type II Metric Radio Bursts
Ramesh Chandra, Apoorv Dashora, P. F. Chen et al. (+1 more)
Solar extreme-ultraviolet (EUV) waves are large-scale disturbances that manifest as bright wavefronts, often during coronal mass ejections (CMEs). According to the
magnetic field line stretching model, this phenomenon comprises two components: a fast-mode CME piston-driven shock wave and a slower, nonwave component. They are often associated with
solar type II
radio bursts. It is expected the
radio source and the fast-mode EUV wave should come from different parts of the same shock, i.e., the CME piston-driven shock, and their speeds should be strongly correlated. To investigate this relationship, we utilized high spatiotemporal resolution observations from the
Solar Dynamics Observatory in conjunction with
radio data from the
Radio Solar Telescope Network. Our analysis reveals that there exists a linear correlation between the EUV fast-mode speeds ($v_{euv}$) and the shock speeds derived from metric (m) type II
radio bursts ($v_{radio}$), which is $v_{radio}=0.89v_{euv}+51$ kms$^{-1}$, with a correlation coefficient of 0.77. This strong correlation suggests that original coronal EIT waves, which are about three times slower than type II
radio bursts, are not fast-mode waves, and it is misleading to map type II
radio bursts to EIT waves in the literature.
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All authors Ramesh Chandra, Apoorv Dashora, P. F. Chen, Pooja Devi