Solar and Stellar Astrophysics
A Modern ConvNet for Solar Filament Detection
J. R. Hu, Q. Hao, Z. Zheng et al. (+3 more)
Automated
solar filament detection using deep learning faces several challenges. Semantic
segmentation of
solar filaments is a complicated multiscale feature extraction task with long-tail distribution. Furthermore, a large-scale, highly complete, and finely detailed
dataset has become mandatory for providing abundant information. To address these challenges, we present a series of machine learning approaches to develop a
solar filament detection workflow that performs superbly. First, we manually annotated a small-scale
solar filament
dataset based on H$\alpha$ spectra called MHAS. Next, we developed the Multiscale ORiented DENdritic (MORDEN) model, a semantic
segmentation model focusing on multiscale feature extraction. We also introduced the Dense Conditional Random Field (DenseCRF) and Density-Based Spatial Clustering of Applications with Noise (DBSCAN) methods for post-processing. Using the proposed workflow, we generated a large-scale, high-quality
dataset called AHAS. Experimental results demonstrate that MORDEN outperforms several existing
solar filament semantic
segmentation models with open access. DenseCRF has been demonstrated to effectively capture fine edge details. We also evaluated the effects of data scaling and the reliability of DBSCAN and found that both approaches yield satisfactory performance. Multiple visualization results substantiate our quantitative findings. Our work provides a foundation for maximizing the potential of deep learning models for
solar filament detection.
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All authors J. R. Hu, Q. Hao, Z. Zheng, P. F. Chen, C. Li, Y. Meng
High Energy Physics (Phenomenology)
Light Dark Matter Discovery Potential and Model Selection at LDMX
Adam Berger, Riccardo Catena, Jan Conrad et al. (+1 more)
Light dark matter (DM) is a compelling scenario for the observed relic abundance, with accelerator-based searches as a powerful discovery strategy. The upcoming Light Dark Matter eXperiment (LDMX) is designed to probe light DM by measuring the energy and transverse momentum of
recoil electrons in high-intensity electron-
nucleus collisions. We evaluate the discovery potential of LDMX to light DM at four
benchmark points along the thermal target for complex scalar DM mediated by a dark
photon, for different background assumptions, and assess its model selection power at a representative
benchmark. We find that LDMX has strong projected 5$\sigma$ discovery potential along the relic target across both background scenarios for certain
benchmarks, and we further compute projected 90% C.L. exclusion limits assuming no measured signal events. The normalization and shape of the two-dimensional
recoil electron distribution encodes the coupling and dark
photon mass, respectively, enabling parameter inference in the event of a signal excess. We perform parameter estimation on simulated data and find that both parameters are recovered within their uncertainties along the relic target. We assess whether the data can distinguish between competing dark sector hypotheses, in particular, dark
photons with additional higher electromagnetic moment interactions. We demonstrate that model comparison using the Bayes factor allows dark sector hypotheses to be statistically distinguished, with the two-dimensional analysis affording substantially greater discriminating power than the one-dimensional analysis. These results are obtained within a likelihood-based statistical framework, incorporating signal and background modelling with their associated systematic uncertainties and employing both frequentist and
Bayesian methods. The framework is designed for direct application to real LDMX data.
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All authors Adam Berger, Riccardo Catena, Jan Conrad, Taylor R. Gray
Quantum Physics
Thermal Quantum Correlations in Coupled Andreev Spin Qubits: Interplay of Superconducting Phase and Spin-Orbit Interaction
Mohammad Reza Pourkarimi, Mina Shiri, Mehdi Monemi et al. (+1 more)
We investigate thermal
quantum correlations in a system of two coupled superconducting
spin qubits described by an effective Andreev
spin-
qubit Hamiltonian in the presence of
spin-orbit interaction. Using Local
Quantum Fisher Information (LQFI) and Local
Quantum Uncertainty (LQU) as
quantum-correlation quantifiers, we analyze the effects of the superconducting phase difference, tunneling amplitude,
spin-orbit coupling, and temperature on the nonclassical properties of the system. Analytical expressions for the thermal density
matrix are obtained and employed to evaluate both quantities. Our results show that
quantum correlations decrease monotonically with increasing temperature, while stronger tunneling and
spin-orbit interaction significantly enhance their robustness. Moreover, the superconducting phase introduces a pronounced periodic behavior through the modulation of the effective exchange couplings, leading to constructive and destructive interference regimes that strongly influence the correlations. By analyzing the energy spectrum of the effective
Hamiltonian, we demonstrate that the enhancement of
quantum correlations is closely associated with an increased energy gap between the ground and first excited states, which suppresses thermal excitations and stabilizes the correlated ground state. Furthermore, LQFI is consistently larger than LQU throughout the investigated parameter space, reflecting its higher sensitivity to
quantum fluctuations and local parameter estimation. These findings reveal the microscopic mechanism governing thermal
quantum correlations in Andreev
spin qubits and highlight the important roles of phase engineering,
spin-orbit interaction, and tunneling in protecting
quantum resources in hybrid superconducting
quantum devices.
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All authors Mohammad Reza Pourkarimi, Mina Shiri, Mehdi Monemi, Vadim Ohanyan
Astrophysics of Galaxies
Time-Domain Dust Astrophysics. I. Polarization Flares, Polarization-Angle Reverberation, and Fossil Imprints in Supernova-Illuminated Clouds
Thiem Hoang
Cosmic transients can enhance the local radiation field on timescales of days to months. Using the time-domain \TransRAT\ framework, which self-consistently follows grain heating,
alignment, rotational disruption, and switching of the
alignment axis between the
magnetic field (B) and the radiation direction (k), we predict the time-dependent
dust polarization of a dense cloud, represented by a homogeneous one-zone model, illuminated by a Type~IIP
supernova over a range of source–cloud distances. We identify four key signatures. First, for $D\lesssim1$~pc, a polarization
flare develops within days to weeks, marked by sharp increases in both thermal
dust polarization and extinction-polarization efficiency; this is followed by a polarization dip as radiative torque disruption (RAT-D) destroys the large aligned grains. Second, the peak wavelength of extinction polarization, $\lambda_{\rm max}$, shifts blueward as the minimum aligned-grain size decreases. Third, the transition from B-RAT to k-RAT produces an abrupt polarization-angle rotation of up to $45^{\circ}$ in our fiducial geometry. Fourth, as the transient fades, the return to B-RAT generates a polarization-angle reverberation governed by Larmor precession. At $D>1$~pc, SN-induced polarization properties can persist long after the radiation has faded. These fossil imprints offer the most practical near-term observational test: clouds near
supernova remnants younger than the relaxation timescale of $\sim10\,t_{\rm gas}$ with $t_{\rm gas}$ gas damping time, should exhibit elevated polarization and blueshifted $\lambda_{\max}$ today. Time-dependent
dust polarization can therefore probe
dust physics,
dust properties, and pristine pre-shock
magnetic fields in real time, while fossil imprints preserve a record of past explosions.
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Atomic Physics
Serrodyne Matterwave Optics
Jack Roth, Madeline Bernstein, Andrew Christensen et al. (+4 more)
Bragg diffraction for atom interferometry conventionally requires two
laser frequencies whose difference makes the two-
photon transition resonant. We show that this frequency difference can instead be generated by serrodyne modulation, allowing Bragg pulses to be driven with a single-frequency
laser. The serrodyne modulation is performed using an acousto-optic modulator driven with a phase-modulated RF drive, and generated kilohertz-scale frequency shifts on top of the AOM carrier frequency. While in general serrodyne modulation generates strong unwanted frequency components, we find conditions so that the Bragg diffraction pulses, and atom interferometers constructed from them, are robust to these imperfections, opening the door to the development of ultra compact, single frequency Bragg diffraction based atom interferometers with serrodyne modulation implemented by a position modulated retroreflection mirror.
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All authors Jack Roth, Madeline Bernstein, Andrew Christensen, Yuno Iwasaki, Holger Mueller, Zaire Sprowal, Robert Compton
Solar and Stellar Astrophysics
Identification of unresolved binaries in the VVV b294 tile: A Pro-Am collaboration using the Virtual Observatory
M. Cortés-Contreras, P. Cruz, E. Solano et al. (+22 more)
Stellar binaries and multiples are common objects. Their identification and characterization are primarily limited by the angular resolution of current instrumentation, survey depth and dynamic range. Towards the
Galactic plane,
stellar crowding further complicates these studies. We aim to identify unresolved binaries with good astrometric solutions and M
dwarf primaries in the b294 field from the Vista Variables in the Vía Láctea (VVV) survey using publicly available data. We examine the catalogue of M
dwarfs within 500 pc in the b294 tile, employing binarity tracers based on statistical parameters from
Gaia Data Release 3, multi-band photometry, and information in the literature. We reassess the astrometric and photometric parameters typically used for binary detection, establishing new boundaries and validating existing ones in the dense
stellar field examined. We compare these results with those obtained in the
solar vicinity. We present 990 unresolved binary candidates and 43 previously known binaries, including five possible triple systems. These represent the 13% of the catalogue, rising to 14.9% in well-covered regions. Binary-model SED fitting yields effective temperatures for 98 primary
stars, with the properties of their secondary candidates indicating that nearly half may be substellar objects. We select 120 of the most promising binary candidates. Tangential velocities, where calculated, place 95% of the studied binary candidates within the young disc population (tau <= 1 Ga). We demonstrate that the influence of nearby
Gaia detections on the statistical parameters is small, allowing constraints similar to those that are applied in less crowded regions.
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All authors M. Cortés-Contreras, P. Cruz, E. Solano, J. L. Navarro, T. Poyato Romero, R. Benavides Palencia, C. Cagigal-Olay, M. Zamora Rodríguez, A. Ginard, S. Langa, J. González-Edo, P. L'Huillier Seguel, E. M. Nicola, V. Pallares-López, M. A. Almela Rubert, J. A. Cano Díez, J. E. Donate Lucas, N. Echevarria Sainz-Ezquerra, A. Elbaz-Sanz, J. M. Espinosa Gallardo, G. Gurrea-Ysasi, J. C. Mora, C. Morales-Socorro, J. M. Perales, A. Romar
Plasma Physics
Impact of ion-electron collisions on nonlocal ion heat conduction, viscous stress, and diffusion
Nicholas Mitchell, David Chapman and Grigory Kagan
By applying a first-principles reduced kinetic method, this work demonstrates the impact of ion-electron collisions on ion transport for strongly inhomogeneous
plasmas in the nonlocal regime, where collisionality is insufficient to enforce local thermal
equilibrium due to sharp gradients. Ion heat conduction and viscous stress in both unmagnetized and magnetized
plasmas are considered, as well as inter-species
diffusion in multi-species
plasmas. Most notably, even for equal ion and electron temperatures, ion-electron collisions are found to substantially modify the peak nonlocal heat flow, whereas nonlocal preheats are strongly suppressed since streaming suprathermal particles are further out in the tail of the cold ion distribution where ion-electron collisions become dominant.
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Medical Physics
Sleep-related forcing of cerebrospinal fluid streaming transport through the third ventricle
Pengcheng Zhao, Luke McTavish and Christoph Bruecker
Quasi-periodic pressure pulses associated with cardiac and respiratory activity generate reciprocating cerebrospinal fluid (CSF) motion in the human ventricles. While weak and more regular during wakefulness, oscillatory fluid motions have recently been found to be much more exaggerated during NREM sleep, appearing as large flushes in successive pulse trains. The present study investigates whether this forcing can induce greater residual streaming through the human ventricles. Transient CFD simulations were performed in the third ventricle under awake and sleep-related flow pulses. Sleep-related forcing produced clear caudal and rostral preferential pathways and less overall recirculation in the cavity. The streaming flux relative to the stroke volume increased from a low value of about \(0.540\%\) to \(28.4\%\) during sleep. Thus, sleep-related forcing changes not only the magnitude of reciprocating fluid displacement but also the relative contribution of residual streaming. These findings demonstrate differences in hydrodynamic organisation in the third ventricle and highlight the importance of this organisation for intraventricular fluid exchange.
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High Energy Physics (Theory)
Spin-resolved double-trace thermal coefficients in holography
Ilija Burić, Ivan Gusev and Andrei Parnachev
It was previously shown that the stress-tensor sector of the OPE, together with the KMS condition, fixes
holographic thermal two-point functions at vanishing spatial separation. We extend this construction to nonzero spatial separation, where the KMS condition leaves a residual ambiguity that depends only on the spatial separation. We show that this ambiguity is fixed by the zero-frequency bulk wave equation, which can be solved analytically in terms of Heun functions. This gives an efficient method for computing thermal coefficients of double-trace operators resolved by
spin. We also study the Lorentzian analytic structure of the resulting correlator and show that complex bulk-cone singularities which appear at spacelike separation in the stress-tensor sector do not persist in the full two-point function; they are resolved by the double-trace contribution.
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Optics
Wearable metasurfaces for boosting the effective area of mobile-device antennas
Mohammad M. Asgari, Xianghui Qiu, Francisco S. Cuesta et al. (+5 more)
Wireless communications increasingly face scenarios with compact user equipments operating in propagation environments where signal blockage, absorption, and device size limitations strongly constrain link performance. Most approaches to wireless-link enhancement focus either on improving base-station
antenna systems, for example, through massive
MIMO architectures; on engineering the propagation environment using reconfigurable intelligent surfaces and active relays. Here, we propose an alternative user-side strategy for improving wireless links based on wearable metasurfaces that enhance the effective
antenna area of compact wireless devices. The proposed passive metasurface is integrated into clothing and engineered to collect the power of electromagnetic waves incident on user's body and route the collected power toward a mobile device in the form of surface waves. This mechanism significantly increases the effective receiving and transmitting area of the device
antenna and its gain without external power sources, active control electronics, or additional stand-alone hardware. We implement the concept on a hoodie textile using a scalable screen-printing process with conductive silver ink and demonstrate an approximately tenfold enhancement of the received signal at 26 GHz. This passive approach effectively brings the human body into the communication network by turning clothing into a virtual thin and flexible lens for focusing the incident power on the user equipment.
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All authors Mohammad M. Asgari, Xianghui Qiu, Francisco S. Cuesta, Shuai S. A. Yuan, Kamil A. Isik, Sergei Tretyakov, Xuchen Wang, Viktar Asadchy
Quantum Physics
Bulk spectra and the non-Hermitian skin effect in systems with long-range couplings
Jonathan Sturm, Pia Kreß and Adriana Pálffy
To achieve translational
symmetry for the computation of the band structure of a
lattice model, one can either consider an infinite
lattice or impose periodic boundary conditions (PBC). While in systems with short-range couplings these two approaches are equivalent, we show that for long-range couplings one can obtain considerably different results. We compare the two methods on the basis of one-dimensional
quantum emitter chains both in free space and when coupled to a waveguide. The latter system allows for asymmetric couplings enabling the non-Hermitian skin effect, which we analyze using the two different band-structure calculation methods. We find that only PBC lead to physically and mathematically robust results, while the infinite-chain approach entails convergence issues and is unable to satisfyingly explain the emergence of the non-Hermitian skin effect in the waveguide system. Using PBC reveals unusual findings like a non-
star shaped generalized Brillouin zone and strongly localized eigenstates with zero winding number.
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High Energy Physics (Phenomenology)
Implications of $K\to\pi\nu\bar\nu$ for new physics in $B$ decays
Lukas Allwicher and Marzia Bordone
The new measurement of the $K^+\to\pi^+\nu\bar\nu$ branching ratio by the NA62 collaboration represents an important milestone in precision flavour physics. Under different flavour assumptions on beyond the standard model physics, this decay mode can be related to many other observables with underlying flavour-changing currents, such as $B\to K\nu\bar\nu$ or $B_s\to\mu\mu$, effectively providing an additional handle in our exploration of flavour-violating new physics effects. We study the impact of this new result, under the hypotheses that deviations from the standard model arise from modified $Z$ couplings, or from effects in semileptonic interactions. Finally, we review the implications of our scenarios for the yet to be measured partner mode $K_L\to\pi^0\nu\bar\nu$.
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Quantum Physics · Cross-listed from math.ST
Optimal estimation of high-dimensional quantum states using locally gentle measurements
Cristina Butucea, Jan Johannes and Henning Stein
We study the task of estimating a $d-$dimensional
quantum state $\rho$ under the constraint that the measurement is $\alpha-$gentle. Such measurements $M$ do not collapse the state; they issue both a random variable $R^M = \omega$ containing statistical information and a post-measurement state $\rho_{M \to \omega}$ such that $\|\rho_{M\to \omega} - \rho\|_{Tr} \leq \alpha$. We describe gentle measurements and their connection to
quantum differential
privacy. Our results show that the optimal minimax estimation rate in Frobenius norm is of order $d^3/(n \alpha^2)$, instead of $d^2/n$ for general measurements. Moreover, for rank $r$ states with $r\leq d$ we prove that the optimal minimax rate is $rd^2/(n \alpha^2)$, instead of $rd/n$. Very surprisingly, the loss for gentleness $d/\alpha^2$ scales with the ambient dimension of the
Hilbert space, rather than the number of parameters $rd$, typically seen in classical differential
privacy. We propose optimal gentle measurements and indicate how they can be physically implemented using an ancillary state and a CNOT gate to entangle it with the initial state. We notice that the resulting random variable has a likelihood that satisfies local differential
privacy. Lower bounds are proven through a new
quantum information-theoretic inequality applied to well chosen families of states in the
manifold of (small-rank)
quantum states.
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Atomic Physics
Nuclear Spin Oscillator Based on $^3$He to Search for Exotic Spin Coupling
Heather R. Pearson, Anna Molodtsova, Sage C. Weisrock et al. (+2 more)
We describe an experimental investigation of a
nuclear spin oscillator based on $^3$He
nuclei as a possible detector to search for exotic
spin couplings. A magnetically shielded vapor
cell comprised of an alkali atom mixture ($95\%$ potassium and $5\%$ rubidium) and $^3$He gas is polarized via
laser light resonant with the $D_1$ transition in rubidium in the presence of a dc
magnetic field. The potassium atoms and $^3$He
nuclei are polarized via
spin-exchange collisions with the polarized rubidium atoms. The
nuclear spins are tipped with a
magnetic field applied perpendicular to the dc
magnetic field. The resulting Larmor precession of the $^3$He
nuclear spins is monitored via Faraday rotation of
laser light near resonant with the $D_1$ transition in potassium. The Faraday rotation signal is filtered, amplified, and used to apply a
magnetic field in a direction perpendicular to the dc
magnetic field, resulting in a self-sustained oscillation of the
nuclear spins at a frequency that is directly proportional to the dc
magnetic field. We demonstrate a sensitivity to exotic
spin couplings that is $\approx 5$ times higher than the alkali atom magnetometers that have been used in the Global Network of Optical Magnetometers to Search for Exotic Physics collaboration.
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All authors Heather R. Pearson, Anna Molodtsova, Sage C. Weisrock, Sherlock Tingrui Zhao, Jason E. Stalnaker
Optics
Experimental Observation of Ghost Image Revivals via Structured Coherence
Weining Wang, Yaning Zhou, Sergey A Ponomarenko et al. (+2 more)
Ghost imaging retrieves an object's image from intensity correlations between two light beams, neither of which independently carries information about the object. However, conventional ghost imaging critically relies on precise object positioning and conjugate matching between the two arms, causing the image to disappear when these conditions are violated and the object is accessible from one plane only. In this Letter, we break this fundamental limitation by reporting the first experimental observation of revivals of ghost images of arbitrary objects via engineering the longitudinal intensity autocorrelation of a structured thermal light field into a coherence comb. With the reference arm fixed, translating the object produces periodic revivals of the ghost image whenever the object position matches a comb-tooth position, reminiscent of the Talbot effect. This capability enhances the flexibility of correlation imaging, enabling robust tomographic imaging of moving and non-periodic complex objects.
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All authors Weining Wang, Yaning Zhou, Sergey A Ponomarenko, Yangjian Cai, Xin Liu
Quantum Physics
A Bohmian version of a 2-state quantum system
Matthew Dickau
I construct a Bohmian version of a 2-state
quantum system, where in addition to the
quantum state, the system is characterized by a definite physical state which changes stochastically under the guidance of the
quantum state. I argue that the probabilities produced by this process are well-defined, contrary to claims in "Why
quantum mechanics cannot be formulated as a Markov process" by D. Gillespie (1994) about a related model.
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Quantum Physics
Two-copy nondistillability of Werner states: sharp partial-trace inequalities and finite-copy extensions
Kishor Bharti, Rishikesh Gajjala and Tobias Haug
We solve the two-copy distillability problem for Werner states in every local dimension. Our main
matrix result is a sharp, dimension-free inequality: for every rank-at-most-two operator, the sum of the squared
Hilbert–Schmidt norms of its two partial traces is bounded by twice its squared
Hilbert–Schmidt norm plus one half of the squared modulus of its trace. This implies that a Werner state $\rho_\alpha$ is two-copy distillable if and only if $\alpha<-1/2$. In particular, the two-ququart state $\rho^{(4)}_{-1/2}$ is two-copy undistillable, resolving Problem 5 of Horodecki, Rudnicki, and Życzkowski. For an arbitrary finite number $k$ of copies, we give three exact formulations of the remaining problem. At the endpoint $\alpha=-1/2$, undistillability is equivalent to nonnegativity of the endpoint partial-trace form on every rank-at-most-two operator. We also derive an equivalent hierarchy of operator inequalities $H_k(\psi)\succeq0$ for pure states with a maximally mixed
qubit marginal. The two-copy proof does not formally induct, because partial trace can increase rank and $2$-positivity is not generally preserved by tensor products. We prove two rigorous many-copy extensions. First, the quadratic form factorizes exactly on tensor-factorized witnesses; for any such decomposition, the endpoint inequality holds if its possible rank-two factor is supported on a block containing at most two copies. Second, we construct explicit constants $\gamma_k>0$ such that $\alpha\ge-\gamma_k$ implies $k$-copy undistillability in every dimension. The initial proofs were generated by ChatGPT 5.6 Sol; the authors have verified and rewritten them to enhance readability and provide additional context.
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Disordered Systems and Neural Networks
Learning limit cycles via Hebbian synaptic plasticity
Samantha J. Fournier, Luca Vincenzo Spallanzani and Pierfrancesco Urbani
We investigate high-dimensional, non-linear dynamical systems when exposed to incoherent periodic inputs and Hebbian-like synaptic plasticity. Our findings reveal a striking phenomenon: depending on the interplay between the strength of the periodic drive and synaptic plasticity, the system's phase diagram can give rise to a region where, once both inputs are removed, the collective dynamics spontaneously settles into a limit cycle. This suggests that periodic drives can imprint lasting rhythmic patterns into the network through plasticity, effectively teaching it to oscillate on its own. Numerical simulations on finite size systems show that the limit cycle phase can be easily detected on single-sample trajectories, while averaged curves are affected by strong finite size effects due to sample-to-sample fluctuations of the period of the limit cycles.
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High Energy Physics (Theory)
Supersymmetric Moduli Space and Vacua with Vector Fields in $D=4$ Gauged $\mathcal{N}=8$ Supergravity
Andrés Anabalón, Stefano Maurelli, Marcelo Oyarzo et al. (+1 more)
When
fermions are taken to be anti-periodic along a spacelike $S^1$ in $AdS_4$, certain ground states of the supergravity theory are described by AdS-
soliton-like spacetimes. We study these geometries within the purely dilatonic STU model obtained from the compactification of M-theory on $S^7$ in the presence of non-trivial gauge fields. The resulting configurations define a rich family of everywhere regular supersymmetric
vacua that holographically describe strongly coupled “confining” gauge theories in three dimensions. We provide a complete characterization of the
moduli space of supersymmetric solutions in terms of the
vacuum expectation values of the dimension-one operators of the truncation.
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All authors Andrés Anabalón, Stefano Maurelli, Marcelo Oyarzo, Mario Trigiante
Quantum Physics
The bare necessities of a physically reasonable mathematical model for quantum theory
Gerd Niestegge
What are the minimal requirements for a physically reasonable mathematical model for
quantum theory or a potential extension? In addressing this question, rather than relying on the generalized probabilistic theories or other usual approaches, we propose a reset based on the following fundamental features: transition probabilities, which are typical of
quantum theory, and continuous reversible dynamical processes (e.g., represented by a Lie group), which play the same crucial role in classical as well as in
quantum physics. In doing so, we get back to the very elementary transition probability space framework originally introduced by Bogdan Mielnik in 1968 and combine it with the continuous reversibility condition. The primary class of valid spaces arises from the irreducible atomic JBW
algebras, which encompass the irreducible atomic von Neumann
algebras and the Jordan
matrix algebras. The von Neumann
algebras represent the model of common
quantum theory. Beyond these, there is a non-standard valid space, where the exceptional Lie group $E_6$ acts transitively. While $E_6$ has been proposed as a candidate for internal
symmetries in particle physics, we highlight that this model deviates from standard
quantum theory in critical ways. Specifically, it fails to guarantee the existence of post-measurement states in all situations. Though the above postulates are powerful, they still allow for some physically meaningless models. A further feature of
quantum theory (the correspondence between the pure states and the minimal projections) leads us to an additional requirement that rules out these models. However, a complete classification of the valid models remains one of the open issues, pointed out in the paper, which is intended for the mathematical and physical experts, inspiring them to tackle these problems.
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Instrumentation and Methods for Astrophysics
The beamformed trigger of RNO-G: its design and in-field performance
RNO-G Collaboration: S. Agarwal, J. A. Aguilar, N. Alden et al. (+75 more)
The
Radio Neutrino Observatory in Greenland (RNO-G) is a
neutrino detector under construction at Summit Station, with 8 out of a planned 35 stations currently deployed. We have designed and deployed a new phased array (PA) trigger based on delay-and-sum beamforming and power integration. This trigger improves detector performance by suppressing thermal noise and better targeting
neutrino-induced Askaryan signals. The new PA trigger has been deployed since the 2025 season. The trigger performance has been characterized using test pulses and calibration pulsers both in the lab and in-situ, and we find across these tests a 25% average reduction in the signal-to-noise ratio (SNR) needed to trigger on signals. Simulations are shown to be representative of the detector, and simulated trigger efficiencies are within 10% of measured data. Following the in-situ trigger validation, we use data-driven trigger performance to inform simulations of the detector effective volumes. The PA trigger increases our effective volume significantly, by over a factor of 2 below 0.1 EeV and at least a factor of 1.3 at the highest energies of 100 EeV.
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All authors RNO-G Collaboration: S. Agarwal, J. A. Aguilar, N. Alden, S. Ali, P. Allison, M. Betts, D. Besson, A. Bishop, O. Botner, S. Bouma, S. Buitink, R. Camphyn, J. Chan, S. Chiche, B. A. Clark, K. Couberly, D. Dakroub, K. D. de Vries, C. Deaconu, P. Giri, C. Glaser, H. Gui, A. Hallgren, J. C. Hanson, S. Hassiki, K. Helbing, B. Hendricks, J. Henrichs, N. Heyer, C. Hornhuber, E. Huesca Santiago, K. Hughes, A. Jaitly, A. Karle, J. L. Kelley, C. Kopper, M. Korntheuer, M. Kowalski, I. Kravchenko, R. Krebs, M. Kugelmeier, D. Kullgren, R. Lahmann, C.-H. Liu, Y. Liu, M. J. Marsee, K. Mulrey, M. Muzio, A. Nelles, A. Novikov, A. Nozdrina, E. Oberla, N. Punsuebsay, M. Ravn, Z. Riesen, A. Rifaie, D. Ryckbosch, F. Schlüter, O. Scholten, P. Schriefer, D. Seckel, M. F. H. Seikh, Z. S. Selcuk, J. Stachurska, J. Stoffels, S. Toscano, D. Tosi, J. Tutt, N. van Eijndhoven, A. G. Vieregg, A. Vijai, H. Warnhofer, D. Washington, C. Welling, D. R. Williams, P. Windischhofer, S. Wissel, A. Zink
General Relativity and Quantum Cosmology
The Higgs vacuum in the presence of strong gravitational fields: curvature induced electroweak symmetry restoration
Paul G. Abel
I investigate the behaviour of the
Higgs field in Schwarzschild spacetime by introducing a Planck-suppressed coupling between the
Higgs field and the Kretschmann scalar, the leading
curvature invariant in
Ricci-flat geometries. I show that spacetime
curvature modifies the
Higgs effective potential, causing the
vacuum expectation value to decrease continuously with increasing
curvature. A critical
curvature is derived at which the
Higgs vacuum expectation value vanishes, signalling a
curvature-induced restoration of electroweak
symmetry. For Schwarzschild black holes, we obtain analytical expressions for the critical
curvature, the corresponding phase-transition radius, and the Planck-
curvature radius that marks the onset of
quantum-
gravity effects. These results identify a self-consistent region inside the event horizon in which electroweak
symmetry is restored while the effective description remains applicable. The model provides a simple analytical framework linking strong gravitational fields to the
Higgs vacuum through a single dimensionless
curvature-
Higgs coupling.
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Materials Science
Neural RHEED alignment with limited training data during CdTe MBE growth
Bartłomiej Turowski, Jakub J. Meixner, Róża Dziewiątkowska et al. (+5 more)
We introduce a data-efficient neural-
vision assisted method to automate crystallographic
alignment during molecular beam epitaxy (MBE) growth. Trained on reflection high-energy electron diffraction (RHEED) patterns from only 15 CdTe structures, our model - enabled by physics-aware postprocessing - reliably infers crystallographic directions, replacing manual frame-by-frame inspection. To this end, we design, test, and critically compare neural-network architectures based on 2D and 3D ResNet configurations, both with and without postprocessing that leverages the physical constraints of RHEED image acquisition. Our work delivers (i) a fully trained neural system ready for closed-loop deployment in future CdTe growth experiments and (ii) a generalizable pipeline for new materials where access to diverse RHEED
datasets is limited. More broadly, this study represents a step toward AI-driven MBE growth and demonstrates the potential of machine-learning-assisted automation in thin-film synthesis.
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All authors Bartłomiej Turowski, Jakub J. Meixner, Róża Dziewiątkowska, Wojciech Zaleszczyk, Tomasz Wojciechowski, Valentine V. Volobuev, Marcin M. Wysokiński, Tomasz Wojtowicz
Astrophysics of Galaxies
Cosmic ray heating of cold streams: Implications for the gas supply and growth of massive galaxies
Ellis R. Owen, Nicolas Ledos, Evangelia Ntormousi et al. (+3 more)
Recent observations have demonstrated the presence of
cosmic rays (CRs) in
cosmic-web filaments. Cold streams supply gas inflows from these filaments into massive
galaxies during the
cosmic noon. As these streams are expected to be magnetised, external
cosmic-web CRs may become entrained with this inflowing gas. We aim to determine whether this externally-supplied CR population can deposit energy to alter or disrupt the supply of cold gas to
galaxies. We couple a spectrally-resolved CR transport calculation to a
redshift-dependent analytical model of magnetised cold streams in
galaxy haloes and investigate whether externally-supplied CRs can modify gas supply through this channel. We find CR energy deposition can alter the thermal state of cold streams. Dense stream cores remain largely resilient and only experience weak heating. Their temperature is raised by less than a factor of 10, which is insufficient to overcome radiative cooling at the stream-CGM interface. In more diffuse streams, and in partially mixed interface gas of the most massive
haloes near the virial radius, CR heating becomes strong enough that radiative cooling can no longer balance it, and the gas is heated toward or above the mixing-layer temperature. This weakens the stability of the stream, making it more susceptible to disruption. Complete evaporation is possible only in extreme cases. Cold streams are therefore more vulnerable to CR heating at larger galactocentric radii, higher
halo masses, and in more diffuse or partially-mixed stream material. By preferentially heating diffuse gas, externally supplied CRs may introduce additional selectivity into cold-gas
accretion that modifies the gas supply and growth of massive
galaxies. These CRs weaken fragile streams and erode their cold envelope, and may cause surviving cold flow components to appear thinner and more sharply confined far into
galaxy haloes.
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All authors Ellis R. Owen, Nicolas Ledos, Evangelia Ntormousi, Shinsuke Takasao, Kentaro Nagamine, Sebastiano Cantalupo
Solar and Stellar Astrophysics
A survey for variable young stars with small telescopes - XI. Spot Lifetimes and Coverage Distributions
Dirk Froebrich, Carys Herbert, Aleks Scholz et al. (+47 more)
We present a homogeneous analysis of rotational variability and spot properties in young
stellar objects across multiple
star-forming regions observed by the Hunting Outbursting Young
Stars (HOYS) project. From over 2000 candidate members, we identify 144 YSOs with robust periodic signals and well-constrained multi-band amplitudes. The sample has a median age of $\sim$1~Myr, effective temperatures of 3500–6500~K (masses $\sim$0.6–2~M$_\odot$), and is dominated by Class~2 objects, one third of which exhibit inner disc
dust emission. The rotation period distribution is strongly bimodal, with 55 percent fast rotators ($P<5.5$~d) and 45 percent slow rotators. Fast rotators are predominantly inner disc-less, whereas slow rotators include both disc-bearing and disc-free systems, indicating that disc braking alone cannot explain the observed rotational states. We derive spot properties from multi-band amplitudes and find that, after correcting for observational biases, the intrinsic cold-spot coverage distribution of fast rotators is well described by an exponential function. This implies that small spot coverages are intrinsically much more common than large ones, consistent with
stochastic magnetic flux emergence governing spot formation. In contrast, slow rotators show a pronounced deficit of small cold spots. After considering observational biases and alternative physical explanations, we conclude that small spots on slowly rotating YSOs have significantly shorter lifetimes. These results provide new evidence that
magnetic surface structure and its
evolution depend on
stellar rotation, placing new empirical constraints on models of
magnetic activity and angular momentum
evolution in young
stars.
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All authors Dirk Froebrich, Carys Herbert, Aleks Scholz, Benjamin W. Ryan, Siegfried Vanaverbeke, Jochen Eislöffel, Cledison Marcos da Silva, Michel Michaud, Kathy Griffiths, Ari M. Siqueira, Thomas Urtly, Francisco C. Soldán Alfaro, George Fleming, Gregg L. Ruppel, Domenico Licchelli, Stephen R.L. Futcher, Ivan L. Walton, Matthias Kolb, Mario Morales Aimar, Geoffrey Stone, Yenal Öğmen, Simon Francis Dawes, Franz-Josef Hambsch, Nick J. Quinn, Juan-Luis González-Carballo, Franky Dubois, José Luis Salto González, Adam Popowicz, Krzysztof Bernacki, Slawomir Bednarz, Tim Nelson, Tony Vale, Tonny Vanmunster, Georg Piehler, Stephen C. Percy, Jordi Berenguer Amatller, Jacopo Fallai, Amritanshu Vajpayee, Faustino García de la Cuesta, Rafael Castillo García, Dawid Moździerski, Krzysztof Kotysz, Przemysław J. Mikołajczyk, Holly Stokes-Geddes, Matthew D. Dickers, Ivana I. Grozdanova, Chiara F. Kawohl, Aashini L. Patel, James S. Urquhart, Tim M. Kinnear
High Energy Astrophysical Phenomena
Evolution of Calvera and Descendants of Calvera-like Central Compact Objects
Ali Arda Gencali, Unal Ertan, Fatmanur Ertugrul et al. (+2 more)
Calvera (1RXS J141256.0+792204) is an isolated
neutron star recently classified as a central compact object (CCO) after its association with the
supernova remnant (SNR) candidate G118.4+37.0. In this work, we investigate the long-term
evolution and descendants of Calvera and the CCOs with similar initial conditions in the fallback disc model. We show that the observed
spin period, period derivative, and X-ray luminosity of Calvera can be reproduced simultaneously with a
magnetic field strength of $\simeq 4 \times 10^{10}$ G at the pole of the
neutron star at an age of $\sim 10^4$ yr which is consistent with the estimated SNR age of the source. In the model, the lack of ordinary
radio pulsations is due to ongoing mass
accretion on to the
star. From our simulations, we estimate that the source will become an ordinary
radio pulsar (RP) after the termination of the
accretion. The source will
spin down under the weak dipole torque alone as an RP for a very long time ($\gtrsim 10^8$ yr) after the inactivation of the disc. From our simulations, we find that most of the CCOs with initial conditions similar to those of Calvera also become RPs which remain above or close to the upper border of the
pulsar death valley after the inactivation of their discs. In the period-period derivative diagram, there is indeed a cluster of RPs in the region where the descendants of Calvera-like CCOs are estimated to be located in our model.
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All authors Ali Arda Gencali, Unal Ertan, Fatmanur Ertugrul, Seyda Demirok, Ndiogou Niang
High Energy Astrophysical Phenomena
Transport Properties of the MRI in Differentially Rotating Neutron Stars
Harshraj Bandyopadhyay, Peter Hammond and David Radice
We perform three-dimensional, high-resolution, general-relativistic magnetohydrodynamics (GRMHD) simulations of the magnetorotational instability (MRI) in differentially rotating
neutron stars. We consider both high-mass models which collapse either promptly, or due to the outward transport of angular momentum removing rotational support, and lower-mass models, which remain stable even after solid-body rotation has been achieved. We measure effective transport coefficients of the resulting turbulent flow, shear-viscosity $\alpha_{\rm vis}$, mixing-length $\ell_{\rm mix}$, and mean-field dynamo $\alpha_{\rm DYN}$-parameter, and their correlations with mean-flow parameters, such as rest-mass density $\rho$, characteristic wavelength of the MRI $\lambda_{\rm MRI}$, and vertical Alfvén velocity $v_A$. At saturation, $\ell_{\rm mix}$ and $\alpha_{\rm DYN}$ correlate with $\lambda_{\rm MRI}$ and $v_A$ respectively, as expected from dimensional analysis. However, both quantities show deviations of roughly an order of magnitude from the values predicted on the basis of these correlations. They are also highly intermittent in space and time. The mixing length is found to be largely independent of density, calling into question the $\ell_{\rm mix}(\rho)$ ansatz used in many general-relativistic large-eddy simulations. Our results show that, while the effects of MRI-induced
turbulence might be qualitatively reproduced by simulations that employ transport coefficients chosen using dimensional-analysis considerations, fully-resolved GRMHD simulations are needed to make quantitative predictions.
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Mesoscale and Nanoscale Physics
Exceptional Cones from an Indefinite Bogoliubov Metric in Hyperbolic Polariton Condensates
Junhui Cao, Kirill Bazarov and Alexey Kavokin
Long-wavelength Bogoliubov
phonons in an ordinary condensate realize the standard acoustic Lorentz metric. We show that a condensate formed in a
hyperbolic polariton band realizes a different collective geometry with an indefinite Bogoliubov metric whose spatial signature is inherited from the opposite signs of the band
curvatures. This metric converts the acoustic light cone into a
hyperbolic stability wedge, separating propagating quasiparticles from dynamically unstable ones. In a driven-dissipative condensate, gain saturation turns this metric relation into a non-Hermitian Bogoliubov dispersion. The zero-discriminant surface becomes an exceptional cone in the parametric space $(q_x,q_y,\Delta_{\rm NH})$, appearing as an exceptional hyperbola at fixed gain saturation. Across this surface the Bogoliubov branches coalesce, the biorthogonal phase
rigidity collapses, and the spectrum changes from propagation to amplified or overdamped dynamics. Our results identify
hyperbolic polariton condensates as a controllable setting where non-Hermitian exceptional degeneracies are organized by an effective Bogoliubov metric.
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Disordered Systems and Neural Networks
A Grand-Canonical Solution to a Class of Random Optimization Problems
Izat B Baybusinov, Enrico M Fenoaltea, Zhen Han et al. (+1 more)
We introduce a general framework to solve a class of combinatorial opti- mization problems, including the matching problem, the Traveling Salesman Problem, and also the minimum weight k-factor problem. By reformulating these problems as an arrangement model, we recast the optimization task into a grand-canonical ensemble, where chemical potentials are used to re- lax strict topological constraints. The analytical solution found can serve as a
polynomial-time
algorithm to compute an approximate minimum cost for arbitrary k and link-weight distributions. Our framework is complementary to existing approaches and reveals new connections between combinatorial optimization and the statistical physics of disordered systems.
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All authors Izat B Baybusinov, Enrico M Fenoaltea, Zhen Han, Yi-Cheng Zhang
High Energy Physics (Phenomenology)
Generation-separated hypercharges and dark charges: origin of flavor, neutrino masses, and dark matter
Duong Van Loi
We study a framework with generation-separated hypercharges and dark charges. After the extended hypercharge
symmetry $U(1)_{Y1}\otimes U(1)_{Y2}\otimes U(1)_{Y3}$ is spontaneously broken to the Standard Model $U(1)_Y$, hierarchical masses of charged
fermions and small
quark mixing can arise from higher-dimensional operators involving hyperon fields. Several realizations with different hyperon sectors are presented to illustrate possible
flavor structures. Focusing on the realization with four hyperons, we examine
neutrino mass generation through either a seesaw or a scotoseesaw mechanism, which can accommodate tiny
neutrino masses and large
neutrino mixing. The breaking of the dark gauge
symmetry $U(1)_D$ leaves a residual $\mathbb{Z}_2$
symmetry that stabilizes dark matter, allowing either fermionic or scalar candidates with viable TeV-scale parameter regions consistent with the observed dark matter relic abundance and current direct detection constraints.
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