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Tuesday 7 July

Earth and Planetary Astrophysics

A generalised microbial cell model for methane biosignature predictions

Arwen E. Nicholson and Nathan J. Mayne

The majority of potentially habitable planets detected to date are likely quite different to Earth, for example, being larger in radius and mass, differing rotation rates and with host star spectra unlike the Sun. Therefore the first alien life detected will potentially be living in conditions not found on our planet. This necessitates a generalised approach to modelling biology that can be applied to numerous planetary scenarios, built on fundamental knowledge of life on Earth, but not limited by it. Here, we explore a generalised model of a microbial cell, whose metabolic rate is governed by thermodynamics and substrate diffusion across its cell wall. We model a single-species biosphere consisting of methane producing microbes and determine how changing the cell size, cell death rate and biomass synthesis cost influence the biosignature on the planet - in this case methane. We discuss approaches to predicting upper estimates for the biosignature gas abundance and the applicability of the model to other metabolisms. This tool adds to the body of work attempting to grapple with the complexity of potential alien biospheres.
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High Energy Physics (Theory)

Compact Syzygies for Feynman Integrals from Landau Singularities

Federico Coro, Pavel P. Novichkov, Ben Page et al. (+1 more)

We discuss a recent proposal for constructing “syzygy solutions”, which play a crucial role in integration-by-parts reductions for multi-loop scattering amplitudes. We highlight a relationship between syzygies and the leading Landau singularities of Feynman diagrams and discuss how this implies that integral relations are controlled by infrared singularities. We use this insight to systematically construct highly compact, determinantal syzygy solutions, providing an explicit, simple example at one loop. We demonstrate the power of this approach by applying it to a two-loop pentabox family relevant for the NNLO corrections to $pp \rightarrow t\overline{t}H$ at the LHC.
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All authors Federico Coro, Pavel P. Novichkov, Ben Page, Qian Song

Fluid Dynamics

Stabilising Evaporating Soap Films with Salt

Victor Ziapkoff, François Boulogne, Anniina Salonen et al. (+1 more)

We investigate the effect of a high concentration (32.5 g.L$^{-1}$) of sodium chloride (NaCl) on TTAB (tetradecyltrimethylammonium bromide) vertical soap films also called foam films, pulled out of a bath under controlled humidity conditions. We observe that the film lifetime increases with relative humidity, both in the presence and absence of salt. At any given humidity, the presence of NaCl systematically enhances film stability. Our film thickness measurements show that the thinning dynamics with or without salt are nearly identical down to 100 nm. Down to that thickness, the effect of evaporation can be rationalised by a constant evaporation rate, which becomes non-negligible compared to the drainage rate at film thicknesses below 400 nm. The main effect of salt is the stabilisation of a Newton black film at a thickness of approximately 5~nm, whereas in the absence of salt, the film ruptures upon reaching a critical thickness of about 10 nm.
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All authors Victor Ziapkoff, François Boulogne, Anniina Salonen, Emmanuelle Rio

Mathematical Physics

Complete hierarchical structure of the spectral bands in the Kohmoto model

Ram Band, Siegfried Beckus and Raphael Loewy

We study the Kohmoto model, a family of discrete Schrödinger operators with Sturmian potentials depending on a frequency and a coupling constant. We prove that, for all non-vanishing coupling constants, all spectral bands admit a hierarchical structure. This structure offers a variety of applications, including a detailed description of the Kohmoto butterfly and a central step towards the resolution of the dry ten Martini problem for Sturmian Hamiltonians, which we carry out in a subsequent work.
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2607.06361 · 7 Jul · This preprint originates from the manuscript first posted as arXiv:2402.16703v1, which has since been split into two parts. The present preprint contains the first part and therefore overlaps with arXiv:2402.16703v1. The revised version arXiv:2402.16703v2 contains the second part. Both parts were carefully edited to form coherent and complementary manuscripts

Abstract PDF $HAML ×1

High Energy Astrophysical Phenomena

The link between extreme particle acceleration and X-ray binary jets

Laura Olivera-Nieto, Fraser J. Cowie, Sera Markoff et al. (+2 more)

The detection of multi-TeV radiation from a handful of black-hole X-ray binaries (BHXRBs) has positioned the source class as promising candidate to explain the cosmic-ray flux in the PeV energy range. To determine what distinguishes the systems detected in the gamma-ray range from the rest of the population, we build on existing catalogues of BHXRBs by including information on the radio and gamma-ray emission from these systems. We then compare the $>100$ TeV gamma-ray luminosity to different properties of the systems and evaluate the strength of the (rank) correlation between them. Additionally, we compare the distribution of BHXRBs with the positions of unassociated gamma-ray sources in the 1LHAASO and 1HGPS catalogues. We find no correlation with the mass of the compact object, the companion mass or the inclination angle. Instead, we find evidence for a strong correlation between the gamma-ray luminosity and the radio and hard-state X-ray luminosities in our sample. The limited number of gamma-ray detections means that this correlation cannot yet be claimed as statistically significant. We find indications that a high (>20%) duty cycle (defined as fraction of time spent in outburst) might be a requirement for $>100$ TeV gamma-ray loudness. We find significant evidence ($>3\sigma$) that BHXRBs are located near unassociated gamma-ray sources in the region of the sky not covered by LHAASO. This evidence is only significant when comparing to BHXRBs with a reported detection in the radio band. We conclude that radio-bright BHXRBs with a high duty cycle are more likely to be detected as gamma-ray sources than sources which are not detected in the radio band or those with low duty cycles. This result suggests that the particles responsible for the gamma-ray emission are associated with the jets, either accelerated within them or via their interaction with their surroundings.
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All authors Laura Olivera-Nieto, Fraser J. Cowie, Sera Markoff, Rob Fender, Justine Crook-Mansour

Solar and Stellar Astrophysics

White dwarfs within 13 pc: insights from ultraviolet spectroscopy

Mairi W. O'Brien, Pier-Emmanuel Tremblay, Boris T. Gänsicke et al. (+10 more)

We present a comprehensive multi-wavelength spectroscopic and photometric analysis of the 44 confirmed white dwarfs within 13 pc of the Sun. Combining flux-calibrated ultraviolet spectroscopy from the Hubble Space Telescope (STIS and COS) with ground-based optical spectroscopy, as well as photometry from Gaia, 2MASS, and WISE, we employ a combined fitting method to calculate atmospheric parameters. Each white dwarf is fitted with a bespoke model depending on its detailed atmospheric composition. Two strongly magnetic stars could not be fitted due to the complex splitting of their spectral lines. We find a systematic discrepancy in hydrogen-atmosphere white dwarfs with effective temperatures below 10,000K, where fits incorporating ultraviolet spectra result in effective temperatures that are 1 - 5 per cent higher than those derived from optical and infrared photometry alone. We re-classify three helium-atmosphere white dwarfs as metal enriched following a magnesium detection in their near-ultraviolet spectra: WD 0435-088, WD 1132-325 and WD 1917+386. In total, we identify five stars in the sample for which metals are only detected in the ultraviolet. Overall, we find that 30 per cent of the 13 pc white dwarfs show spectroscopic evidence of evolved planetary systems. Our analysis reveals no measurable difference between the hydrogen content of DQ and DC white dwarfs, although the upper limits of carbon in DCs are significantly below that of the DQ population. We find a multiplicity fraction of 33 per cent for the 13 pc white dwarfs.
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All authors Mairi W. O'Brien, Pier-Emmanuel Tremblay, Boris T. Gänsicke, Mark A. Hollands, Detlev Koester, Snehalata Sahu, Antoine Bédard, Andrew M. Buchan, Tim Cunningham, John H. Debes, Jay Farihi, J. J. Hermes, Piotr M. Kowalski

High Energy Physics (Experiment)

Efficiency measurements of GEM GE1/1 chambers in the upgraded CMS Endcap Muon System using 2023 collision data at $\sqrt{s}=13.6$ TeV

M. Abbas, S. Abbott, M. Abbrescia et al. (+184 more)

The CMS experiment at the Large Hadron Collider employs Gas Electron Multiplier (GEM) detectors, a technology based on gaseous ionization, as one of the muon detectors. The muon spectrometer is being upgraded to handle the increased muon flux in the forward region. This study analyzes muon detection efficiency in the GE1/1 triple-GEM detector, using 2023 proton-proton collision data at $\sqrt{s}=13.6$ TeV. A dataset enriched with muons from Z boson decay, with a total recorded luminosity of 17.8 fb$^{-1}$ has been used for this study. The detection efficiency of 137 GEM detectors are measured using muon trajectories established using other detectors in the tracking and muon systems, without use of the GEM detectors. The average efficiency of 137 GEM detectors is $\sim$93.3$\%$. A subset of 108 detectors that had no shorts were operated at the nominal HV working point with average efficiency of $\sim$96$\%$. Efficiency is found to be unaffected by the number of p-p interactions per bunch crossing (pile-up).
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All authors M. Abbas, S. Abbott, M. Abbrescia, H. Abdalla, A. Abdelalim, S. AbuZeid, D. Aebi, A. Ahmad, W. Ahmed, C. Aimè, T. Akhter, G. Alasfour, M. Ali, B. Alsufyani, A. Aravind, C. Aruta, I. Asghar, P. Aspell, C. Avila, Y. Ban, R. Band, S. Bansal, N. Beni, L. Benussi, T. Beyrouthy, V. Bhatnagar, M. Bianco, S. Bianco, K. Black, O. Bouhali, S. Brachet, A. Braghieri, M. Brunoldi, M. Buonsante, S. Butalla, A. Cagnotta, S. Calzaferri, R. Campagnola, M. Caponero, F. Cassese, N. Cavallo, B. Chauhan, S. S. Chauhan, B. Choudhary, M. Citron, S. Colafranceschi, A. Colaleo, A. Conde Garcia, A. Datta, P. Danev, A. De Iorio, G. De Lentdecker, G. De Robertis, W. Dharmaratna, C. Di Fraia, D. Dobur, E. Ehlert, R. Erbacher, P. Everaerts, F. Fabozzi, F. Fallavollita, L. Favilla, M. Franco, C. Galloni, L. Generoso, Y. Gharbia, P. Giacomelli, S. G. Gigli, J. Gilmore, G. Gokbulut, R. Hadjiiska, T. Hebbeker, K. Hoepfner, M. Hohlmann, H. Hoorani, T. Huang, P. Iaydjiev, A. Iorio, F. Ivone, W. Jang, J. Jaramillo, E. Juska, B. Kailasapathy, T. Kamon, Y. Kang, P. Karchin, S. Keshri, D. Kim, H. Kim, J. Kim, M. Kim, S. Kim, A. Kumar, S. Kumar, N. Lacalamita, J. S. H. Lee, Q. Li, Z. Li, F. Licciulli, L. Lista, K. Liyanage, F. Loddo, L. Longo, M. Luhach, M. Maggi, N. Majumdar, K. Malagalage, S. Malhotra, S. Martiradonna, M. Merschmeyer, M. Misheva, G. Mitev, G. Mocellin, S. Muhammad, S. Mukhopadhyay, M. Naimuddin, F. Nenna, S. Nuzzo, R. Oliveira, S. Ostrom, M. Otkur, E. Paoletti, P. Paolucci, I. C. Park, G. Passeggio, A. Pellecchia, N. Perera, L. Petre, B. Philipps, D. Piccolo, D. Pierluigi, C. Prakash, R. Radogna, A. Ranieri, D. Rathjens, B. Regnery, C. Riccardi, M. Rodríguez, B. Rossi, P. Rout, A. A. Ruales, J. D. Ruiz-Àlvarez, A. Russo, A. Safonov, A. K. Sahota, M. Saini, D. Saltzberg, G. Saviano, A. Schmidt, A. Sharma, T. Sheokand, M. Shopova, F. M. Simone, J. Singh, K. Skovpen, U. Sonnadara, A. Stamerra, G. Sultanov, Z. Szillasi, D. Teague, R. Tesauro, D. Teyssier, S. Thakur, D. Troiano, M. Tytgat, I. Vai, R. Venditti, P. Verwilligen, W. Vetens, A. K. Virdi, P. Vitulo, A. Wajid, D. Wang, A. Warden, I. J. Watson, N. Wickramage, D. D. C. Wickramarathna, E. Yanes, U. Yang, Y. Yang, H. D. Yoo, I. Yoon, Z. You, I. Yu, S. Zaleski, A. Zaza, C. Zhou

High Energy Physics (Phenomenology)

Dispersive estimation of the LO hadronic contribution to the muon ${g-2}$: fitting incompatible ${e^+e^-}$ data

V.V. Bryzgalov and O.V. Zenin

Using an up-to-date compilation of $\sigma_{\mathrm{tot}}(e^+e^- \to hadrons)$ data we estimated the LO hadronic contribution to the muon anomalous magnetic moment, $a_\mu(had,LO)$. Incompatibilities between $\sigma_{\mathrm{tot}}(e^+e^- \to hadrons)$ measurements by independent experiments are mitigated by extra systematic uncertainties estimated using as a guideline a requirement of uniformity of $\chi^2$ distribution over degrees of freedom in joint fits of $\sigma_{\mathrm{tot}}$. Tensions in the $e^+e^-$ input data translate into an expanded uncertainty of the $a_\mu(had,LO) = (697.7 \pm {9.8}_{e^+e^-} \pm 3.6_{sys}) \times 10^{-10}$. Given this, we obtain the SM prediction for the muon anomaly $a_\mu^{\mathrm{SM}} = 11659185.5(10.6) \times 10^{-10}$, below the experimental world average $a_\mu^{\mathrm{exp}}$ at $2\sigma$ level.
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Fluid Dynamics

Suppressing wall modes in confined rotating turbulent convection

Lázaro Martínez-Ortíz, Maarten Minartz, Youri H. Lemm et al. (+3 more)

In confined turbulent rotating convection, the largest vertical velocities are found near the sidewalls in the form of wave-like structures known as wall modes. These structures persist deep into the turbulent regime, bias heat transport, and disrupt bulk flow organisation through radial jets. Controlling or suppressing wall modes is, therefore, essential for accessing bulk dynamics free from wall-induced effects. Here, we combine experiments and direct numerical simulations to investigate wall modes control in cylindrical cells equipped with ring-shaped sidewall barriers. Barriers suppress vertical-velocity maxima near the sidewall and disrupt the characteristic wave-like pattern. Simulations further show that the barriers reduce the wall-mode-induced enhancement of heat transport, shifting it towards values characteristic of laterally periodic domains. The suppression efficiency is governed by the ratio of the barrier width to the wall-mode scale and is enhanced by the addition of a second barrier. In the horizontal plane, radial jet ejections are attenuated, while the time-averaged flow reveals suppression of the boundary zonal flow (BZF), a ring-shaped region of positive azimuthal velocity near the sidewall, provided measurements are taken away from the immediate vicinity of the barriers. In this region, isotherms bend toward the poorly conducting barrier, creating a local misalignment with the isobars and inducing a baroclinic flow adjacent to the barrier faces. This effect weakens with increasing barrier conductivity or smoother geometry. These results demonstrate that sidewall barriers provide a robust route for suppressing wall modes signatures in experimental turbulent rotating convection, while locally inducing secondary baroclinic flows near the barriers. Their use enables access to extreme rotating-convection regimes with reduced sidewall influence.
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All authors Lázaro Martínez-Ortíz, Maarten Minartz, Youri H. Lemm, Xander M. de Wit, Herman J. H. Clercx, Rudie P. J. Kunnen

Computational Physics · Cross-listed from cs.LG

Physics-Informed Neural Embeddings of PDE Solution Families

Raul Jimenez, Svitlana Mayboroda, Pavlos Protopapas et al. (+3 more)

We introduce a physics-informed framework for learning finite-dimensional embeddings of solution families of partial differential equations. The method uses a multihead Physics-Informed Neural Network in which a shared body learns a latent manifold representing the solution space, while linear heads reconstruct individual solutions associated with different initial conditions. A head-orthogonalization penalty removes degeneracies in the latent representation and stabilizes the principal-component spectrum across training realizations. Because the initial condition is built into the network output by construction, these principal components measure the additional variability the network learns on top of the initial profile, not the full solution itself. We apply the method to the one-dimensional viscous Burgers equation, with the heat and wave equations as robustness checks. For a latent dimension $n_b=20$, the learned manifolds exhibit pronounced effective dimensional reduction: for Burgers dynamics, only $2$-$4$ principal components capture about $95\%$ of the latent-space variance, while $4$-$7$ capture about $99\%$, depending on the initial-condition family; the same qualitative compression holds for the heat and wave equations. We also split the wavenumber axis into bands (“Fourier shells”) and measure how much each band contributes to every principal component. The resulting frequency profile is invariant under the change-of-basis freedom that the orthogonalization penalty leaves in the latent space, and is therefore reproducible across independent training runs. More broadly, this establishes the learned spectral profiles and principal components as robust observables of solution-manifold geometry.
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All authors Raul Jimenez, Svitlana Mayboroda, Pavlos Protopapas, Leonid Sarieddine, David N. Spergel, Pedro Tarancón-Álvarez

High Energy Astrophysical Phenomena

Unravelling Turbulence and Magnetic Fields in Galaxy Clusters with SKA and XRISM

Kohei Kurahara, Takuya Akahori, Amit Seta et al. (+5 more)

This chapter proposes a research framework to quantitatively investigate non-thermal components in the Intracluster Medium (ICM) of galaxy clusters, which are critical ingredients for governing energy transport, structure formation, and particle acceleration. Turbulence, primarily driven by cluster mergers, is the leading mechanism for re-accelerating cosmic ray electrons (forming radio halos) and amplifying magnetic fields (via the turbulent dynamo). Observational understanding of both the turbulence and magnetic fields is rapidly evolving: the high-resolution X-ray spectrometer XRISM is directly measuring the velocity properties of the thermal ICM, providing insights into the kinetic energy of turbulence. Concurrently, high-sensitivity low-frequency radio observations, including SKA pathfinders, are mapping non-thermal components and magnetic structures through diffuse synchrotron emission and high-density Faraday Rotation Measure (RM) grids. The synergy between XRISM and SKA offers a decisive paradigm shift. XRISM's velocity maps, with its high energy resolution (<7 eV FWHM), combined with SKA-Mid's capability to deliver high-resolution RM grids ($\sim 100$–$200~\rm deg^{-2}$) and high-dynamic-range imaging, will allow for the first direct, multi-wavelength comparison of the turbulent energy properties (from X-ray) and the magnetic field properties (from radio). This joint analysis will validate Magnetohydrodynamic (MHD) simulation predictions, clarify the process of turbulent energy cascade and decay, and ultimately lead to a comprehensive understanding of the co-evolution of turbulence, magnetic fields, and cosmic rays in the largest laboratories of the Universe.
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All authors Kohei Kurahara, Takuya Akahori, Amit Seta, Kosuke Nishiwaki, Kazuhiro Nakazawa, Yuki Omiya, Daisuke Ito, Kosei Sakai

Mesoscale and Nanoscale Physics

Radio frequency readout and control of Ge/SiGe hole spin qubits with a global accumulation gate

Tien-Ho Chang, Chi-Wei Lee, Jian-Chang Zeng et al. (+12 more)

Hole spin qubits in undoped Ge/SiGe quantum well structures have advanced rapidly in performance and scalability. However, stringent multi-layer patterning and overlay requirements of conventional overlapping-gate devices create a bottleneck for academic proof-of-concept experiments involving few-qubit devices. Here we present fabrication and measurements of Ge/SiGe spin qubit devices with a global accumulation gate and single-layer depletion fine gates, which substantially reduce fabrication complexity. With careful design of the gate-2DHG capacitance, we demonstrate RF-based single-shot spin readout and coherent control of two single-spin qubits. We also characterize the spin coherence times and exchange tunability, which are similar to those reported in recent overlapping-gate Ge/SiGe spin qubit devices. By simplifying fabrication without sacrificing performance, our approach offers a more accessible device design for spin-based quantum technology research.
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All authors Tien-Ho Chang, Chi-Wei Lee, Jian-Chang Zeng, Chia-Hao Wei, Ching-Shiang Wang, Fu-Yuan Gu, Guan-Yu Yang, Ruei-Syuan Chiang, Ho-Chun Wu, Ming-Hao Lee, Ming-Wen Chu, Guang Li Luo, Ta-Chun Cho, Shawn S. H. Hsu, Tzu-Kan Hsiao

Solar and Stellar Astrophysics

Spectral Ratio Analysis: probing of a new suite of stellar activity indicators as a tool for astrophysical noise mitigation

Jean C. Costes, Christopher A. Watson, Ernst de Mooij et al. (+6 more)

Stellar activity is the main barrier to detecting and/or confirming low-mass/long-period (and Earth-analogue) planets using radial-velocity (RV) measurements. Searching for reliable indicators that better trace magnetic activity may be key for both distinguishing more clearly between stellar and planetary signals, and for probing the underlying physics occurring on the stellar surface. In this work we have compared observations taken for magnetically active and inactive stellar phases over multiple time scales to study the spectral imprint due to varying stellar activity. This serves as a proof-of-concept demonstration of a technique (named Spectral Ratio Analysis, SRA) that can be used to isolate activity-driven changes directly in the stellar photospheric absorption lines where RVs are measured. Using 14 relatively quiet and well sampled G- and K-type stars that show stellar activity cycles, we identified hundreds of activity-sensitive spectral features. Reducing this variability information into two global metrics – amplitude and velocity shift – uncovers potential evidence of a decoupling of the photospheric and chromospheric responses to stellar activity in earlier-type stars. Additionally, potential signatures of the variations in the magnitude of the suppression of the convective blueshift throughout the activity cycle were observed via SRA. Finally, we show that these SRA indicators better capture RV variability than classical activity proxies, such as the chromospheric logR'HK index and other cross-correlation function-based parameters such as BIS and FWHM, by up to a factor of two. The direct link between photospheric line behaviour and stellar-induced RV variability offers a promising path for improving astrophysical noise mitigation.
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All authors Jean C. Costes, Christopher A. Watson, Ernst de Mooij, Katlyn L. Hobbs, Dana Clarice S. Yaptangco, Yvonne C. Unruh, Megan Bedell, Nadège Meunier, Thomas D. Mitchell

High Energy Astrophysical Phenomena

SN 2022erq: A Superluminous Thermonuclear Supernova with Escalating Preexplosion Mass Loss

Qian Zhai, Jujia Zhang, Xiaofeng Wang et al. (+51 more)

We present a photometric and spectroscopic study of the superluminous Type Ia supernova SN 2022erq. Its early spectra, dominated by iron-group elements with weak intermediate-mass features, might indicate highly efficient nuclear burning, broadly similar to that inferred for some overluminous SNe Ia. The rapid emergence and persistence of narrow Balmer emission lines superposed on this iron-rich spectrum provide clear evidence of long-lived interaction with a hydrogen-rich circumstellar medium (CSM), establishing SN 2022erq as a member of the rare Ia-CSM class. SN 2022erq reached a peak bolometric luminosity of about 8 x 10^43 erg/s and exhibited an exceptionally slow post-peak decline, indicating that its light curve is dominated by long-duration ejecta-CSM interaction. By combining H-alpha diagnostics with bolometric light-curve modeling, we reconstruct the pre-explosion mass-loss history of the progenitor. The mass-loss rate escalated by one order of magnitude over the final decades, rising from about 0.04 to about 0.6 solar masses per year. This surge produced a massive, extended CSM shell of about 3 solar masses out to about 3.5 x 10^16 cm. The young stellar environment (about 100 Myr) together with this substantial, extensive CSM points to a progenitor system consisting of a white dwarf and an intermediate-mass companion that underwent increasing mass loss prior to explosion.
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All authors Qian Zhai, Jujia Zhang, Xiaofeng Wang, A. Pastorello, Alexei V. Filippenko, József Vinkó, Thomas G. Brink, Yunkun Han, G. Valerin, N. Elias Rosa, Yongzhi Cai, Weili Lin, Yi Yang, WeiKang Zheng, Xiangcun Meng, Chengyuan Wu, Liping Li, Zeyi Zhao, J. Craig Wheeler, Jose L. Prieto, Jialian Liu, Gaici Li, Shengyu Yan, Fangzhou Guo, C. P. Gutiérrez, E. Kankare, Peter Lundqvist, S. Moran, A. Reguitti, I. Salmaso, M. D. Stritzinger, S. Williams, J.-W. Zhao, D.-D Shi, Jianrong Shi, Z.-H. Peng, Tengfei Song, Yongyuan Xiang, Attila Bódi, Borbála Cseh, Ágoston Horti-Dávid, Csilla Kalup, Levente Kriskovics, Réka Könyves-Tóth, András Pál, Bálint Seli, Ádám Sódor, Róbert Szakáts, P. A. Mazzali, T. Kravtsov, K. Matilainen, T. M. Reynolds, L. Galbany, Bo Wang

Quantum Physics · Cross-listed from math.CO

Enumeration of Laplacian integral and {-1,0,1}-diagonalizable graphs

Nathaniel Johnston, Sarah Plosker and Luis M. B. Varona

A graph with Laplacian matrix $L$ is called Laplacian integral if the eigenvalues of $L$ are all integers, and it is called $\{-1,0,1\}$-diagonalizable if $L$ has a full set of eigenvectors with entries from $\{-1,0,1\}$. We herein develop a structure theorem for both Laplacian integral graphs and $\{-1,0,1\}$-diagonalizable graphs of prime order, and combine it with some novel computational techniques to characterize all such graphs for orders larger than was previously possible. For example, we enumerate all Laplacian integral and $\{-1,0,1\}$-diagonalizable graphs of order $13$ or less, all $\{-1,0,1\}$-diagonalizable graphs of prime order $23$ or less, all regular integral graphs of order $15$ or less, and all regular $\{-1,0,1\}$-diagonalizable graphs of prime order $53$ or less. As an immediate byproduct of our work, we show that the $S_{n,n}$ conjecture for Laplacian integral graphs is true when $n = 12$, thus making $n = 16$ the smallest open case; additionally, we disprove two related conjectures regarding Laplacian spectra. We also establish an exponential lower bound on the number of connected $\{-1,0,1\}$-diagonalizable graphs of order $n$, thus beating the previously best-known (subexponential) lower bound. Finally, we show that every bipartite $\{-1,0,1\}$-diagonalizable graph is regular (a fact that fails to generalize to Laplacian integral graphs).
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Solar and Stellar Astrophysics

The Best Guess: Testing new and old formalisms for the common envelope against observations

Riley Thai, Amanda I. Karakas, Zara Osborn et al. (+4 more)

We present a systematic test of formalisms for common envelope evolution by forward-modelling observable post-common envelope binaries. We compare predictions from the $\alpha$-formalism, and the Two-stage and SCATTER formalisms against observed post-common envelope binaries, including wide binaries with ultra-massive white dwarfs and central binaries of planetary nebulae. The angular momentum-based SCATTER formalism does not predict populations which match the complete observed population, even with adjustments to its parameters. We take this as indicative of fundamental challenges with using the orbital angular momentum balance to predict common envelope outcomes. The energy-based $\alpha $ and hybrid Two-stage formalisms both well-replicate the observed population. $\alpha_{\rm CE} \sim 0.2\text{--}0.3$ can match current observations, in agreement with previous works. Recombination energy is necessary, but only a fraction of it ($\sim\! 10\text{--}40\%$) can contribute in order to predict IK Peg-like binaries with ultra-massive white dwarfs at the correct orbital periods. Our work suggests energy-based formalisms remain the most accurate for predicting common envelope outcomes, but more observations can constrain the recombination contribution and how these outcomes systematically vary with the donor mass.
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All authors Riley Thai, Amanda I. Karakas, Zara Osborn, Robert G. Izzard, Ryosuke Hirai, Alex J. Kemp, Simon W. Campbell

Superconductivity

Anomalously high quasiparticle thermal conductivity in the underdoped cuprate superconductor HgBa$_{2}$CuO$_{4+\delta}$

Jordan Baglo, Quentin Barthélemy, Étienne Lefrançois et al. (+4 more)

The single-layer cuprate superconductor HgBa$_{2}$CuO$_{4+\delta}$ (Hg1201) is an ideal candidate for investigating many properties of cuprates with minimal disorder and without the complication of multiple CuO$_2$ layers. Here we measure the in-plane longitudinal thermal conductivity $\kappa$ of underdoped Hg1201 ($T_c$ = 76 K, $p$ = 0.11) at dilution refrigerator temperatures to extract the nodal quasiparticle velocity ratio $v_F/v_\Delta$. Assuming contributions from only a single line node per quadrant on the Fermi surface leads to a value of $v_F/v_\Delta$ = $23 \pm 3$, anomalously large compared to other cuprates at similar dopings. In conjunction with the anomalously high quasiparticle specific heat of Hg1201 in the normal state reported previously at a similar doping, this points to more than one Fermi surface sheet crossing the nodal line, suggesting the presence of more than the single small electron pocket detected by quantum oscillations.
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All authors Jordan Baglo, Quentin Barthélemy, Étienne Lefrançois, Anne Forget, Dorothée Colson, Cyril Proust, Louis Taillefer

Atomic Physics

Ionization-free femtosecond UV pulse filamentation resulting from non-perturbative Kerr effect saturation due to transient photoexcitation of molecules

V. V. Strelkov, A. V. Shutov and V. D. Zvorykin

Our experimental and numerical study of filamentation of the 248 nm 100 fs pulses in air, nitrogen, and oxygen at atmospheric pressure shows that the densities of photoelectrons in the filaments are not sufficient to limit Kerr self-focusing. The simulations explain this result, showing that the nonlinear refractive index growth with the UV intensity is saturated due to transient photoexcitation of a molecule, not the photoionization. Correct simulation of the observed filament intensity ratio in different gases validates the suggested mechanism of the femtosecond UV pulses filamentation.
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Statistical Mechanics

Robust q-negative Multifractal Detrended Cross-Correlation Coefficient

Thiago B. Murari, José Fernando F. Mendes, Hernane B. B. Pereira et al. (+1 more)

The multifractal detrended cross-correlation coefficient $\rho_q(n)$ is widely used to investigate scale-dependent interactions, but its application to negative fluctuation orders is affected by numerical instabilities, unbounded values, and interpretational difficulties. We propose a Signed Multifractal Detrended Cross-Correlation Coefficient, $\rho_{\mathrm{SMFDCCA}}(n,q)$, an amplitude-conditioned correlation observable for multifractal detrended analysis, based on locally normalized detrended correlations and regularized fluctuation amplitudes. The proposed coefficient preserves the sign of local interactions, remains strictly bounded within $[-1,1]$ for both positive and negative values of $q$, and eliminates the corrective procedures required by previous approaches. Validation using independent fractional Gaussian noise confirms the absence of spurious cross-correlations and the numerical stability of the method. Applications demonstrate that the proposed observable resolves how cross-correlations evolve jointly with temporal scale and fluctuation amplitude, revealing scale- and amplitude-dependent correlation structures, including stronger synchronization during large fluctuations in stock-market indices and heterogeneous coupling patterns in temperature records.
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All authors Thiago B. Murari, José Fernando F. Mendes, Hernane B. B. Pereira, Marcelo A. Moret

Fluid Dynamics

Strain-Rate-Consistent $\varepsilon$-Based Non-Premixed Flamelet Model

Sylvain L. Walsh, Yalu Zhu, Feng Liu et al. (+1 more)

This numerical study examines a strain-rate inconsistency in the conventional flamelet/progress-variable (FPV) formulation for non-premixed combustion and proposes an alternative coupling based on the turbulence kinetic energy dissipation rate, $\varepsilon$. Two-dimensional Reynolds-averaged Navier-Stokes (RANS) simulations of a transonic accelerating reacting mixing layer are performed using one-step kinetics, a conventional FPV model, and the proposed $\varepsilon$-$Z$ flamelet model. The analysis focuses on the relation between the RANS-computed mean strain-rate field and the local strain rate imposed on the flamelet through the coupling between the flow computation and the flamelet library. In the FPV formulation, the flamelet state is selected through a transported progress variable, whose evolution is governed by advection, diffusion, and chemical production rather than by the local strain-rate environment. The present results show that this can lead to preferential sampling of near-equilibrium flamelet states in high-strain regions, thereby weakening the intended connection between the computed flow field and the strain-rate-controlled flamelet response. In the $\varepsilon$-$Z$ formulation, $\varepsilon$ is used to infer the imposed flamelet strain rate, $S^*$, so that the local flamelet state is directly constrained by the modeled turbulence field and the pressure-dependent flammability limit. Selected species are transported explicitly, allowing products to persist through locally quenched regions, while a reactant-availability scaling limits tabulated source terms when the transported composition departs from the flamelet manifold.
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All authors Sylvain L. Walsh, Yalu Zhu, Feng Liu, William A. Sirignano

General Relativity and Quantum Cosmology

Polarization images of non-topological soliton Bardeen boson stars

Xiao-Xiong Zeng, Chen-Yu Yang, Ke-Jian He et al. (+1 more)

In this study, we investigate the polarized images of non-topological soliton Bardeen boson stars by solving the coupled Einstein nonlinear electrodynamics complex scalar field equations, based on the thin accretion disk model surrounding these compact objects. We focus on the influence of key parameters, including the initial scalar field, magnetic charge, observer inclination angle, and magnetic field configuration, on the resulting polarization characteristics. The results show that the geometry of the magnetic field, particularly the relative strength between the radial \(B_r\) and angular \(B_\theta\) components, plays a crucial role in determining the polarization pattern. Additionally, variations in the scalar field amplitude and magnetic charge significantly affect both the intensity and spatial distribution of the polarization. These results show that the polarization morphology is sensitive to the spacetime geometry and magnetic field configuration, and provide a qualitative basis for comparing boson stars with black holes.
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All authors Xiao-Xiong Zeng, Chen-Yu Yang, Ke-Jian He, Li-Fang Li

Instrumentation and Methods for Astrophysics

Long-term performance of SiPMs in space environment measured by GRBAlpha, GRBBeta, and VZLUSAT-2 CubeSats

Jakub Ripa, Filip Munz, Marianna Dafcikova et al. (+46 more)

In this work, we report the successful application of silicon photomultipliers (SiPMs) in gamma-ray burst (GRB) detectors used in CubeSats operating in the low Earth orbit (LEO) radiation environment. It is known that SiPMs are susceptible to radiation damage, leading to an increase in the dark count rate. This results in an increase in the low-energy threshold in detectors combining SiPMs and scintillators. Despite this drawback, they became popular in gamma-ray detectors on CubeSats due to their low operating voltage, small size and fast response. Therefore, it is important to characterise their long-term performance in the space environment. Here, we describe the changes in the dark count rate and low-energy threshold of S13360-3050PE multi-pixel photon counters (MPPCs) by Hamamatsu Photonics K.K., using measurements from the GRBAlpha, GRBBeta, and VZLUSAT-2 CubeSats. In the case of GRBAlpha, the measurement of SiPM performance in space lasted over 4 years. GRBAlpha was a 1U CubeSat launched on 2021/03/22 to a 550 km altitude polar orbit carrying a CsI(Tl) scintillator GRB detector employing eight MPPCs and sensitive in the range of ~30-900 keV. GRBAlpha de-orbited on 2025/06/09. VZLUSAT-2 was a 3U CubeSat launched on 2022/01/13 to a 535 km altitude polar orbit and de-orbited on 2025/11/30. GRBBeta was launched on 2024/07/09 to a 580 km altitude, 62{\deg} inclination orbit. Both VZLUSAT-2 and GRBBeta carry detectors similar to the one on GRBAlpha. We have flight-proven the Hamamatsu MPPCs S13360-3050 PE and demonstrated that SiPMs, shielded by 2.5 mm of PbSb alloy, can be used in a LEO environment on a scientific mission lasting beyond 4 years. This shows the potential for SiPMs to be employed in future satellites.
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All authors Jakub Ripa, Filip Munz, Marianna Dafcikova, Andras Pal, Norbert Werner, Masanori Ohno, Laszlo Meszaros, Balazs Csak, Pavel Kosik, Michaela Duriskova, Lea Szakszonova, Martin Kolar, Tomas Vitek, Nikola Husarikova, Filip Hroch, Michal Pazderka, Yasushi Fukazawa, Hiromitsu Takahashi, Tsunefumi Mizuno, Jean-Paul Breuer, Masato Yokota, Kazuhiro Nakazawa, Hirokazu Odaka, Yuto Ichinohe, Tomas Urbanec, Ales Povalac, Miroslav Kasal, Miroslav Smelko, Peter Hanak, Gabor Galgoczi, Martin Topinka, Hsiang-Kuang Chang, Tsung-Che Liu, Chih-Hsun Lin, Chin-Ping Hu, Che-Chih Tsao, Kaustubha Sen, Chih-En Wu, Jakub Kapus, Jan Hudec, Marcel Frajt, Maksim Rezenov, Vladimir Daniel, Petr Svoboda, Juraj Dudas, Martin Sabol, Ivo Vertat, Robert Laszlo, Martin Koleda

High Energy Physics (Phenomenology)

$KX(3872)$ interaction and correlation function

Jing Song, Pedro Brandao and Eulogio Oset

We investigate the $K X(3872)$ interaction and the corresponding correlation function, assuming the $X(3872)$ to be a molecular state of $D \bar D^*$ and $D^* \bar D$ with isospin $I=0$ and positive $C$-parity. The interaction is treated within the fixed-center approximation (FCA) to the Faddeev equations, in which the $X(3872)$ is taken as a cluster of its constituents and the kaon interacts with the $D^*$ and $D$ components. The three-body scattering amplitude is evaluated using the Fixed Center Approximation (FCA) to the Faddeev equations, improved by taking the FCA amplitude as an optical potential which is later unitarized by means of the Lippmann-Schwinger equation. We find a narrow resonant structure about 50~MeV below the $K^+ X(3872)$ threshold with a width of approximately 1~MeV, and determine the $K X(3872)$ scattering length $a = (0.39 - i\,0.00)$~fm and effective range $r_0 = (1.16 - i\,1.66)$~fm. The corresponding correlation function is evaluated and shows a clear deviation from unity at low momenta, characteristic of a strongly attractive interaction leading to a bound state. These predictions are tied to the molecular nature of the $X(3872)$ and can be measured experimentally via measurements of the $K X(3872)$ correlation function and three-body invariant mass distributions.
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Astrophysics of Galaxies

Low-Frequency Recombination Lines from Galaxies and AGN over Cosmic Time

Kimberly L. Emig, Sergei Balashev, Francoise Combes et al. (+10 more)

Radio recombination lines (RRLs) at low frequencies (<10 GHz) can provide a multi-phase view of interstellar gas in nearby galaxies, absorption-line-systems, and AGN. Hydrogen RRLs arise in fully ionized gas and carbon RRLs trace elusive cold-HI and CO-dark molecular gas. Low frequency RRLs are typically stimulated by the radio continuum and thus may be observable within or against radio bright sources out to cosmological distances (z ~ 6). Although long sought after, RRLs were only recently detected outside of the local universe (z ~ 1; Emig et al., 2020, 2023). Such detections have been made possible by the advancement of wide-bandwidth spectral-line surveys on next-generation low-frequency telescopes. Precursors and pathfinders to the SKA have opened up this field of research and will make significant advancements over the next years by enabling surveys over large source samples. The SKA will provide access to the crucial frequency ranges where RRL line intensity is brightest. Furthermore, multi-band SKA measurements will fully characterize gas physical conditions. Key extragalactic science of low frequency RRLs will focus on (i) the conversion of baryonic material into stars across cosmic time, (ii) the evolution of the ISM and its physical conditions in galaxies, and (iii) how gas drives and inhibits AGN activity.
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All authors Kimberly L. Emig, Sergei Balashev, Francoise Combes, Lucie Cros, Bjorn Emonts, Neeraj Gupta, Antoine Gusdorf, Emmanuel Momjian, Sébastien Muller, Elaine M. Sadler, Pedro Salas, Alexander G. G. M. Tielens, Ilsang Yoon

Cosmology and Nongalactic Astrophysics

Kinetic structure of the intracluster medium across nearby clusters observed with XRISM

Naomi Ota, Erwin T. Lau, Satoshi Yamada et al. (+2 more)

XRISM/Resolve is building a sample of galaxy clusters with directly measured ICM gas motions, revealing diverse projected dynamical states. We compile 45 XRISM/Resolve measurements in 19 nearby galaxy clusters and place them on a common, emission-weighted effective line-of-sight scale, $\ell_{\rm eff}$. We compare the line-of-sight velocity dispersion $\sigma_v$, bulk velocity amplitude $|v_{\rm bulk}|$, their ratio $R_v \equiv |v_{\rm bulk}|/\sigma_v$, and non-thermal pressure proxies. Disturbed non-cool-core systems are not simply higher-dispersion counterparts of relaxed cool-core regions. Instead, differences among cool-core centers, cool-core outer regions, and non-cool-core systems are driven mainly by coherent line-of-sight motion relative to unresolved line broadening: $R_v$ tends to remain below unity in cool-core regions but often exceeds unity in non-cool-core systems, with the mean $R_v$ rising from 0.45 in cool-core centers to 1.6 in non-cool-core systems. These diagnostics help separate local central line broadening, likely associated with AGN feedback in some cool cores, from larger-scale coherent motions associated with sloshing, mergers, and halo assembly. Comparison with forward-modeled TNG-Cluster predictions suggests that many cool-core measurements occupy the lower part of the predicted non-thermal pressure range, consistent with small hydrostatic-mass corrections in relaxed systems and larger corrections in disturbed ones. XRISM is thus beginning to resolve the projected kinetic structure of the ICM across cluster environments, rather than tracing a single sequence of increasing turbulence.
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All authors Naomi Ota, Erwin T. Lau, Satoshi Yamada, Yuki Omiya, Hiroya Yamaguchi

Instrumentation and Methods for Astrophysics

Instrument response generation using high-resolution 3D voxelization of GRBAlpha and VZLUSAT-2 satellites with MEGAlib

Jean-Paul Breuer, Masato Yokota, Yasushi Fukazawa et al. (+24 more)

Pathfinder gamma-ray burst (GRB) detecting CubeSat missions such as GRBAlpha and VZLUSAT-2 have demonstrated the successful application of scintillator detectors with silicon photomultipliers in low Earth orbit (LEO). To produce more comprehensive scientific analysis of the data, the effective area of the detector needs to be characterised at different energies. A large part of this process requires a thorough understanding of the detectors response matrices based on the satellite mass model typically performed through Geant4 and MEGAlib simulations. We use a novel voxelization and binning methodology to turn complex 3D geometries into MEGAlib-compatible versions, and we validate these experiments by showing that the simulation results with Geant4 agree within an order of 10%. We use MEGAlib simulations from various angles around the spacecraft to generate instrumental response matrices for both simple and complex geometries, in the case of GRBAlpha and VZLUSAT-2, respectively.
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All authors Jean-Paul Breuer, Masato Yokota, Yasushi Fukazawa, Hiromitsu Takahashi, Norbert Werner, Jakub Ripa, Marianna Dafcikova, Filip Munz, Masanori Ohno, Balazs Csak, Laszlo Meszaros, Andras Pal, Marcel Frajt, Jan Hudec, Jakub Kapus, Maksim Rezenov, Vladimir Daniel, Juraj Dudas, Petr Svoboda, Hsiang-Kuang Chang, Hao-Min Chang, Chin-Ping Hu, Chih-Hsun Lin, Tsung-Che Liu, Kaustubha Sen, Che-Chih Tsao, Chih-En Wu

Earth and Planetary Astrophysics

The deep atmosphere of Jupiter

Keren Duer-Milner

Jupiter, a rapidly rotating gas giant, features over 20 atmospheric jet streams that penetrate thousands of kilometers into the planet. This work discusses recent progress, identifies key uncertainties regarding the jets' driving and dissipating mechanisms, and suggests future research avenues.
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Quantum Physics

Quantum Probabilistic Local Differential Privacy: Structural Properties and Sample Complexity Bounds

Xian Shi

Differential privacy provides a rigorous framework for quantifying privacy leakage in data analysis, while its quantum extensions have become increasingly relevant with the development of quantum computing and quantum machine learning. In this work, we introduce and study quantum probabilistic local differential privacy, a relaxation of quantum local differential privacy in which the privacy constraint is allowed to fail on a spectral violation event with low probability. This quantity can be interpreted as the probability under the quantum superoperation of a quantum privacy-loss violation, and is closely related to the acceptance probability of the quantum Neyman-Pearson test at a small threshold. We investigate the basic structural properties of this privacy notion and clarify its relationship with existing forms of quantum differential privacy. We show the properties of quantum probabilistic local differential privacy under tensor-product composition and unitary post-processing, while it is in general neither convex nor closed under post-processing by arbitrary quantum channels. We further characterize when depolarizing noise satisfies quantum probabilistic local differential privacy under several representative scenarios. Finally, we connect quantum probabilistic privacy constraints with statistical inference by deriving a lower bound on probabilistically privatized contraction coefficients in terms of the hockey-stick divergence. As an application, we obtain sample complexity bounds of probabilistically privated asymmetric and symmetric quantum hypothesis testing. These results provide a systematic foundation for studying probabilistic privacy guarantees in quantum information processing and their operational consequences for private quantum statistical inference.
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Instrumentation and Methods for Astrophysics

Exploring Image-Text Alignment for Radio Galaxy Morphologies

Erica Lastufka, Mariia Drozdova and Svyatoslav Volosynovskiy

We investigate whether specially constructed text captions can capture the same morphological information as radio galaxy images. Using the MiraBest dataset, we generate captions with a domain-specific prompt and evaluate their alignment with images through the SigLIP-2 vision–language model, with and without LoRA fine-tuning. Results show that caption-based classification of FR-I and FR-II galaxies performs similarly to images, with fine-tuning improving local coherence of embeddings but not global alignment.
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Superconductivity

Decoupling Josephson Coupling and Supercurrent Nonreciprocity in Twisted NbSe2/NbSe2 van der Waals Junctions

Seung-Gi Lee, Kwon-Neong Jung, Jae-Kuen Kim et al. (+4 more)

The microscopic origin of supercurrent nonreciprocity in van der Waals Josephson junctions remains under active debate, particularly regarding the role of twist-angle engineering in layered superconductors. Here, we investigate superconducting transport in twisted NbSe2/NbSe2 vertical Josephson junctions fabricated by dry transfer with controlled crystallographic alignment and chemically clean interfaces. High-resolution transmission electron microscopy is employed to directly determine the twist angle and assess interface quality. While the Josephson coupling strength exhibits a pronounced dependence on twist angle, with characteristic voltages maximized near crystallographically equivalent orientations and suppressed at intermediate angles, the supercurrent diode efficiency remains negligibly small and shows no systematic twist-angle dependence. In contrast, enhanced diode-like responses emerge only in weakly coupled junctions exhibiting interfacial disorder and reduced transparency. Deliberate interface degradation further amplifies the apparent nonreciprocity, yielding diode efficiencies approaching 30% together with an irregular magnetic-field-strength dependence. These results establish a clear decoupling between Josephson coupling and supercurrent nonreciprocity in twisted NbSe2/NbSe2 junctions. Our findings identify interface disorder, rather than twist-angle-controlled momentum matching, as the dominant origin of the observed diode response and provide a critical benchmark for interpreting nonreciprocal superconducting transport in van der Waals Josephson devices.
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All authors Seung-Gi Lee, Kwon-Neong Jung, Jae-Kuen Kim, Jae-Chun Jeon, Jiho Yoon, Stuart S. P. Parkin, Kun-Rok Jeon