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Physics

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Wednesday 24 June

Astrophysics of Galaxies

Spectroscopic surveys with the SKA probing the ionized and molecular Milky Way

A. Karska, J.R. Dawson, A.M. Jacob et al. (+12 more)

Radio spectroscopic surveys provide us with a comprehensive picture of the Milky Way across many physical and chemical regimes. Spectral lines primarily probe the multi-phase gaseous interstellar medium (ISM) from its ionized to atomic and molecular phases, and constrain both local and galaxy-scale kinematics and structure through Doppler shifts. By investigating the physical and chemical properties and distribution of the ISM, the processes driving star formation and galaxy evolution can be studied in detail. This motivates line surveys of our Galaxy that allow us to use the range of physical conditions found in the Milky Way as a template for understanding star formation in extragalactic environments. In this chapter, we describe the science enabled by the spectroscopy of small molecules and radio recombination lines of atoms toward a range of Galactic environments with the SKA. We address questions concerning the processes that dictate the formation of molecular clouds (OH, CH), the properties of warm, ionized gas and the potential of HII regions in understanding the structure of the Galaxy (radio recombination lines), and the impact of CO-dark molecular gas across various density regimes on star formation and galaxy evolution (OH, H2CO). We propose a survey that includes the inner and outer Galaxy disk, characterized by a broad range of densities, temperatures, and metallicities. Deep, wide-field observations of small molecules will be uniquely accessible with SKA, providing key insights on the condition of interstellar medium in galaxies and its impact on star formation.
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All authors A. Karska, J.R. Dawson, A.M. Jacob, T.V. Wenger, J.S. Urquhart, D. Colombo, L.D. Anderson, V.S. Veena, M. Rugel, M.A. Thompson, P.D. Klaassen, H. Beuther, M.P. Busch, A. Traficante, G. Sabatini

High Energy Astrophysical Phenomena

Two years of shock interaction tracing three phases of evolution: the explosion of a Type IIn supernova, SN 2019vxm

Gitika Rameshan, Rishabh Singh Teja, D. K. Sahu et al. (+10 more)

We present multi-wavelength photometric and optical spectroscopic observations of the long-lived interacting supernova SN 2019vxm, spanning more than two years after the explosion. SN 2019vxm is a slowly rising (rise time ~ 45.9 days in the R-band), slowly declining supernova reaching an R-band peak absolute magnitude of ~-20.3 mag. The SN light curve post-maximum shows a shallow decline, followed by a secondary, steeper decline in the optical (0.01 mag/day), with late-time IR brightening. The total radiated luminosity is 5x10^50 erg, placing it among the energetic class of its type. We estimated a CSM mass of 3-8 M_sun through light-curve modeling (independent of the CSM density profile) and by comparison with theoretical models. We estimate a minimum ejecta mass of ~ 3.88 M_sun from the broad H-alpha component, consistent with the ejecta mass obtained from the light curve models. The solely interaction-dominated initial epochs are later accompanied by photon-scattering signatures, leading to asymmetric line profiles with symmetric wings. The late phase, characterized by enhanced brightness at longer wavelengths and a stronger asymmetric line profile with the red side flux strongly suppressed, indicates the influence of pre-existing or newly formed dust with temperatures ~ 1500 K at ~4x10^16 cm. Even in the late phases, no nebular lines are present in the spectra, indicating dense or obscured ejecta.
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All authors Gitika Rameshan, Rishabh Singh Teja, D. K. Sahu, G. C. Anupama, Masayuki Yamanaka, Keiichi Maeda, Tatsuya Nakaoka, Sota Goto, Brajesh Kumar, Avinash Singh, Miho Kawabata, Koji S. Kawabata, Kenta Taguchi

Adaptation and Self-Organizing Systems

An Isochron-Free Framework for Phase Reduction and Coupling Inference

Akari Matsuki, Ryota Kobayashi and Hiroshi Kori

Phase description provides a compact and powerful framework for analyzing synchronization dynamics in weakly coupled limit-cycle oscillators. While its classical formulation relies on the asymptotic phase defined by isochrons, reconstructing isochrons from observed trajectories is often challenging for complex models and real-world systems. Here we develop an isochron-free framework based on a readily computable generalized phase, such as the polar angle computed from observed trajectories. We theoretically show that, under near-uniform rotation of the generalized phase and sufficiently stable amplitude dynamics, a one-period stroboscopic description yields a closed circle map. The interaction term of the resulting circle map coincides, to leading order, with the phase coupling function obtained from the conventional phase reduction. Based on this circle map, we propose a method to infer coupling from oscillatory time series. The method is validated using synthetic data from van der Pol oscillators. Our framework broadens the applicability of phase reduction and provides a theoretically grounded method for coupling inference from oscillatory data.
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Materials Science

The interplay of interfaces, supramolecular assembly, and electronics in organic semiconductors

Belinda J. Boehm, Huong T.L. Nguyen and David M. Huang

Organic semiconductors, which include a diverse range of carbon-based small molecules and polymers with interesting optoelectronic properties, offer many advantages over conventional inorganic semiconductors such as silicon and are growing in importance in electronic applications. Although these materials are now the basis of a lucrative industry in electronic displays, many promising applications such as photovoltaics remain largely untapped. One major impediment to more rapid development and widespread adoption of organic semiconductor technologies is that device performance is not easily predicted from the chemical structure of the constituent molecules. Fundamentally, this is because organic semiconductor molecules, unlike inorganic materials, interact by weak non-covalent forces, resulting in significant structural disorder that can strongly impact electronic properties. Nevertheless, directional forces between generally anisotropic organic-semiconductor molecules, combined with translational symmetry breaking at interfaces, can be exploited to control supramolecular order and consequent electronic properties in these materials. This review surveys recent advances in understanding of supramolecular assembly at organic-semiconductor interfaces and its impact on device properties in a number of applications, including transistors, light-emitting diodes, and photovoltaics. Recent progress and challenges in computer simulations of supramolecular assembly and orientational anisotropy at these interfaces is also addressed.
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Astrophysics of Galaxies

Cosmic evolution of the helium and oxygen abundances in type 2 Active Galactic Nuclei: Helium-loud AGNs

O. L. Dors, M. Armah, G. F. Hägele et al. (+14 more)

We derive the helium and oxygen abundances in the Narrow Line Regions (NLRs) of 84 Active Galactic Nuclei (AGNs) spanning two redshift ranges: 65 objects at $z \: < \: 0.2$ and 19 objects at $2.8 \lesssim z \lesssim 6.8$. Spectroscopic data in the optical rest-frame range [3000 ${\lambda}(\text{\AA})$ 7000] from the JADES survey and from the literature were used to estimate $\text{He/H}$ and $\text{O/H}$ via the $T_{\rm e}$-method (7 objects) and strong-emission line calibrations (19 objects). Our results indicate that the ionization degree in AGNs increases toward higher redshifts, exhibiting a trend similar to that observed in star-forming galaxies. We find that the majority of our sample of AGNs at $z \: > \: 2.8$ show oversolar helium abundances and subsolar oxygen abundances. We identified, via the $T_{\rm e}$-method, an object (goods-s-mediumhst-58850; $z=6.2615$) with the highest helium abundance estimated to date, i.e. $12+\log({\rm He/H})=11.64$, corresponding to $\rm (He/He_{\odot}) \sim 4.4$. This result remains robust even when we adopt larger electron densities (varying $N_{\rm e}$ from $500$ to $10\:000$ $\rm cm^{-3}$) in abundance estimates using the $T_{\rm e}$-method and empirical strong-line methods. We found marginal evidence for a decline in the He/H abundance ($\sim 0.04$ dex per redshift unit) toward lower redshifts. In contrast, we found evidence for an increase in $\text{O/H}$ toward the local universe at a rate of approximately 0.06 dex per redshift unit.
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All authors O. L. Dors, M. Armah, G. F. Hägele, M. V. Cardaci, P. C. Santos, R. A. Riffel, G. Cresci, R. Riffel, L. N. Marinho, X. Ji, Y. Isobe, R. Maiolino, A. Marconi, A. Feltre, R. L. Sanders, I. N. Morais, G. C. Almeida

Quantum Physics

Resonant false vacuum decay in two dimensions on a 4000-qubit quantum annealer

Gregor Humar, Jean-Yves Desaules, Luka Pavešić et al. (+4 more)

From cosmology to quantum matter, metastable states often decay through the nucleation and growth of competing domains, with false vacuum decay providing the paradigmatic example of this process. Here we demonstrate a distinct regime in which domain growth outpaces nucleation by orders of magnitude and is controlled by local resonance conditions. Using a programmable quantum annealer with more than 4000 qubits, we realize a two-dimensional quantum Ising model whose metastable spin-polarized state encodes a false vacuum. At a specific value of the longitudinal field, single-spin flips at the boundary of a seeded bubble become resonant, enabling kinetically constrained expansion. Combining experiment with tensor-network simulations and stochastic circuit modeling, we observe nearly ballistic growth of true-vacuum domains with sub-ballistic interface broadening, consistent with Kardar–Parisi–Zhang universality. Our results establish a growth-dominated regime of false vacuum decay and show how large-scale quantum simulation can access nonequilibrium metastable dynamics relevant to quantum field theory, cosmology, and strongly correlated matter.
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All authors Gregor Humar, Jean-Yves Desaules, Luka Pavešić, Marko Ljubotina, Zlatko Papić, Kristel Michielsen, Jaka Vodeb

Astrophysics of Galaxies

Euclid Quick Data Release (Q2) – The Euclid Galactic Bulge Survey

J.-P. Beaulieu, E. Bachelet, M. Gilles et al. (+173 more)

The Euclid Quick Data Release Q2 provides an unprecedented deep, wide-field, high-angular-resolution view of the inner Galactic bulge through the Euclid Galactic Bulge Survey (EGBS). Nine contiguous fields covering 4.8 deg$^2$ were observed with the VIS instrument over 24 hours in March 2025. Unlike the nominal Euclid survey strategy, the EGBS employed 16 dithered exposures of 400 s each, corresponding to a total integration time of 1.8 hours per field. Dedicated calibration observations were obtained to derive point spread functions (PSFs). The primary objective of the EGBS is gravitational microlensing, with high-angular-resolution imaging enabling lens-mass measurements to better than 10%. The survey provides an optical reference dataset for previously discovered microlensing events and future observations of the Galactic bulge. The Q2 data were processed with the VIS-PF pipeline. The non-standard observing strategy required dedicated calibration products, while the extreme stellar density necessitated modifications to the astrometric calibration and cosmic-ray detection procedures. These improvements have since been incorporated into later pipeline versions. We describe the motivation, observing strategy, data processing, products, and first results of the EGBS. Astrometric residuals with respect to the Gaia DR3 catalogue are 5.5 mas in right ascension and 4.4 mas in declination across the survey area, while the photometric zero points are calibrated to 1.5%. The Q2 release includes calibrated single-dither images, dedicated PSF models, and photometric catalogues containing approximately 45 million detected sources per dither down to AB magnitude 26. Although incomplete because of extreme crowding, these products provide a robust astrometric and photometric foundation for future exploitation of the dataset.
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All authors J.-P. Beaulieu, E. Bachelet, M. Gilles, C. Ranc, E. N. Rektsini, E. Kerins, M. T. Penny, H. Verma, S. Mottet, R. Vavrek, V. Bozza, J.-C. Cuillandre, M. Chang, L. R. Bedin, K. Kuijken, C. Laigle, M. Libralato, I. McDonald, R. Nakajima, V. Popoff, J. Rhodes, E. Thygesen, S. Awan, J. E. Davies, A. M. Di Giorgio, T. Flanet, C. Grenet, O. Herent, P. Hudelot, K. Jahnke, R. Kohley, H. J. McCracken, H. N. Nguyen-Kim, M. Page, M. Schirmer, F. Soldano, B. Altieri, S. Andreon, N. Auricchio, H. Aussel, C. Baccigalupi, M. Baldi, A. Balestra, S. Bardelli, P. Battaglia, R. Bender, A. Biviano, M. Brescia, S. Camera, V. Capobianco, C. Carbone, V. F. Cardone, J. Carretero, M. Castellano, G. Castignani, S. Cavuoti, A. Cimatti, C. Colodro-Conde, G. Congedo, C. J. Conselice, L. Conversi, Y. Copin, F. Courbin, H. M. Courtois, M. Cropper, H. Degaudenzi, G. De Lucia, C. Dolding, H. Dole, F. Dubath, X. Dupac, S. Dusini, S. Escoffier, M. Farina, R. Farinelli, F. Faustini, S. Ferriol, F. Finelli, S. Fotopoulou, N. Fourmanoit, M. Frailis, L. Gabarra, S. Galeotta, W. Gillard, B. Gillis, C. Giocoli, P. Gómez-Alvarez, A. Grazian, F. Grupp, L. Guzzo, W. G. Hartley, S. V. H. Haugan, G. Helou, S. Hemmati, H. Hoekstra, W. Holmes, I. M. Hook, F. Hormuth, A. Hornstrup, M. Jhabvala, B. Joachimi, S. Kermiche, B. Kubik, M. Kümmel, M. Kunz, H. Kurki-Suonio, R. Laureijs, A. M. C. Le Brun, S. Ligori, P. B. Lilje, V. Lindholm, M. Magliocchetti, G. Mainetti, O. Mansutti, O. Marggraf, M. Martinelli, N. Martinet, F. Marulli, R. J. Massey, E. Medinaceli, M. Melchior, M. Meneghetti, E. Merlin, G. Meylan, A. Mora, M. Moresco, C. Moretti, L. Moscardini, C. Neissner, S.-M. Niemi, J. W. Nightingale, C. Padilla, S. Paltani, F. Pasian, W. J. Percival, V. Pettorino, G. Polenta, M. Poncet, G. D. Racca, F. Raison, A. Renzi, G. Riccio, I. Risso, F. Rizzo, E. Romelli, M. Roncarelli, B. Rusholme, R. Saglia, Z. Sakr, A. G. Sánchez, D. Sapone, P. Schneider, T. Schrabback, A. Secroun, E. Sihvola, P. Simon, C. Sirignano, G. Sirri, J. Skottfelt, L. Stanco, P. Tallada-Crespí, A. N. Taylor, I. Tereno, S. Toft, R. Toledo-Moreo, F. Torradeflot, A. Tsyganov, I. Tutusaus, J. Valiviita, T. Vassallo, Y. Wang, J. Weller, A. Zacchei, F. M. Zerbi, E. Zucca, M. Sereno

High Energy Physics (Theory)

From Cosmological Cuts to Yang–Mills Wavefunctions in de Sitter Space

Song He, Jiajie Mei and Yuyu Mo

We study tree-level Yang–Mills wavefunctions in four-dimensional de Sitter space using their discontinuities. Cosmological cuts factorize gluon discontinuities into lower-point wavefunctions glued by cut propagators and transverse projectors. For ray-like trees and one-loop $n$-gons, the maximal cuts take a particularly simple form: a scalar $\phi^3$ discontinuity dressed by an ordered Yang–Mills numerator built from local gluing maps. We then use these cuts as reconstruction data for the four-, five-, and six-gluon wavefunctions in momentum space. The result separates into a cut-detectable part obtained from lower-point gluing and a cut-invisible completion fixed by current conservation and the flat-space limit. Through six points, the terms without longitudinal propagators follow the pole structure of color-ordered scalar $\phi^3+\phi^4$ wavefunctions, dressed by local Yang–Mills numerators. Longitudinal propagators collapse part of this scalar structure into contact-type contributions, with the first internal-line corrections appearing at six points. The reconstructed expressions agree with direct momentum-space Feynman-rule computations and give concrete low-point data for an all-$n$ organization of spinning de Sitter wavefunctions.
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Adaptation and Self-Organizing Systems · Cross-listed from q-bio.NC

Topology-Dependent Emergence of Polychronous Neuronal Groups: A Recurrence-Plot Characterization

Lucas A. T. X. Carneiro, Armand D. Jiofack and Fernando F. Ferreira

Polychronous Neuronal Groups (PNGs) reproducible, time-locked spatiotemporal firing cascades stabilised by Spike-Timing-Dependent Plasticity (STDP) and heterogeneous axonal delays provide a combinatorially rich substrate for neural computation whose structural determinants remain poorly understood. We simulate a recurrent network of N=1000 Izhikevich neurons over ten hours of biological time and identify 1545 unique PNGs via an offline event-driven detection algorithm. A parametric Watts-Strogatz topology sweep reveals that the clusteringcoefficient C is the primary structural driver of PNG yield: the transition from a ring-lattice (C~0.35, $\sim\!850$ \PNGs) to a random graph (C~!0.20$, $<\!50$ \PNGs) reduces representational capacity by more than 90%. We further introduce a sparse-dot-product Recurrence Plot (RP) framework that identifies PNGs as unit-slope diagonal structures in the phase-space recurrence matrix, entirely independent of anatomical neuron labelling. Recurrence Quantification Analysis yields DET~0.65, quantifying the reproducibility of the network's dynamical trajectory. Together, the results establish small-world topology as the structural optimum for polychronization and the \RP decoder as a principled, label-free tool for PNG identification.
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Optics

Sensitivity of Fitting High Order Zernikes

Gregg M. Gallatin

The sensitivity of fitting Zernike coefficients to wavefront data due to an error or uncertainty in the exact position of the edge of the wavefront data is derived. The results indicate that fitting higher and higher order Zernikes rapidly becomes a useless exercise unless the true edge of the wavefront data is known with sufficient precision.
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Physics and Society

Collective variables for homophily-driven network rewiring dynamics

Sören Nagel, Stefanie Winkelmann, Péter Koltai et al. (+2 more)

Stochastic network rewiring processes, in which edges dynamically rewire based on fixed node attributes, are widely used in applications ranging from social dynamics to neuroscience and form an important component of adaptive network modelling. In this paper, we identify low-dimensional collective variables (CVs) that capture the essential macroscopic behavior of such time-evolving networks and enable reduced-order descriptions of their dynamics. To this end, we apply the data-driven transition manifold approach to homophily-driven rewiring models, in which edges preferentially connect nodes with similar attributes. For two representative models, we find that the optimal CV is a consensus measure quantifying the fraction of edges whose incident nodes differ by less than a certain threshold. Building on the learned CV, we construct reduced macroscopic models using a data-driven approach based on sparse regression and through an analytical derivation using graphons. The latter yields a closed-form evolution equation for the consensus measure and analytically validates the identified CV.
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All authors Sören Nagel, Stefanie Winkelmann, Péter Koltai, Nataša Djurdjevac Conrad, Marvin Lücke

Quantum Physics

Evolving Quantum Error-Correcting Encodings for Molecular Simulation

Kenny Heitritter, James Brown and Tarini Hardikar

Useful quantum algorithms require many coupled discrete design choices. We study LLM-driven evolutionary program synthesis – a language model edits a program, an external verifier scores the result, and high-scoring programs are retained and re-mutated – as a tool for quantum-computing research. As a case study, we apply this loop to the Generalized Superfast Encoding (GSE), a fermion-to-qubit encoding whose prior molecular constructions reach code distance $3$. The search discovered interpretable constructor programs whose codes have exact distance $5$ on the molecular instances tested, and distance $6$ on one $20$-mode instance, under strict stabilizer-coset semantics. To our knowledge these are the first GSE/superfast encodings beyond distance $3$ for dense molecular Hamiltonians. A second search, guided by verifier analysis of the first artifact, found a circulant constructor that reaches a five-qubits-per-mode floor on the tested $12$-, $14$-, $16$-, and $20$-mode instances, with certified dense-rule fallback at the failing $18$-mode case. As secondary resource descriptors, in a code-capacity memory comparison at $p=10^{-3}$ the resulting encodings use $4.2$–$5.0\times$ fewer data qubits than a scoped per-mode Jordan–Wigner $+$ $[[25,1,5]]$ surface route and have $3.4$–$8.2\times$ lower logical-failure rates under finite-weight decoding tables with explicit truncation brackets; we claim no circuit-level fault-tolerance or Trotter-cost advantage. The search trajectory illustrates a general operating lesson: rewarding distance alone selects trivial dense graphs, whereas holding verified distance fixed and rewarding compression selects structured rules.
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High Energy Physics (Phenomenology)

Leptonic CP asymmetry and heavy neutrino searches in seesaw scenario

Arindam Das, Wei Liu and Supriya Senapati

We investigate the prospects for probing heavy Majorana neutrinos in the type-I seesaw framework at the 14 TeV LHC. In this scenario, the light-heavy neutrino mixing enables the production of heavy neutrinos in association with charged leptons, followed by decays into dilepton plus dijet final states. We perform a detector-level cut-based analysis of both same-sign (SS) and opposite-sign (OS) dilepton channels and investigate the sensitivity as a function of the ratio $R_{ll}$ of SS to OS events. We derive projected constraints on the light-heavy neutrino mixing as a function of the heavy-neutrino mass. For $R_{ll} \simeq 1$, the sensitivity at $140~\rm{fb}^{-1}$ improves upon current LHC bounds by about one order of magnitude for $M_N \simeq 60-80~\rm{GeV}$, with a further order of magnitude improvement expected at the HL-LHC with $3~\rm{ab}^{-1}$. The sensitivity decreases substantially for smaller $R_{ll}$. We show that, for $50~\text{GeV} \lesssim M_N \lesssim 100~\text{GeV}$, the collider reach is strongly correlated with $R_{ll}$ and the associated CP asymmetry, providing additional motivation for future measurements of $R_{ll}$ and heavy-neutrino oscillations at colliders.
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High Energy Astrophysical Phenomena

Broadband multiwavelength properties of the archetypal blazar 3C 279 during the 2017 Event Horizon Telescope campaign

G. Principe, J. C. Algaba, E. Aviano et al. (+530 more)

The archetypal blazar 3C 279 hosts a prominent relativistic jet and exhibits strong broadband variability across the electromagnetic spectrum. In April 2017, the Event Horizon Telescope (EHT) observed 3C 279, alongside one of the most extensive quasi-simultaneous multiwavelength (MWL) campaigns ever conducted. With the aim of investigating the physical processes governing 3C 279, we analyzed individual observations and multiband light curves, and constructed a new quasi-simultaneous MWL spectrum. We also performed phenomenological modeling using the turbulent extreme multi-zone (TEMZ) model to constrain the fundamental physical properties of the source. The EHT observations reveal a clear flux increase in the innermost core between April 5 and 11, 2017. Over a broader timescale, radio measurements at longer wavelengths show concurrent enhancements in core flux and polarization around mid-April, coinciding with the ejection of a superluminal knot. Record UV-optical flares with strong polarization variability occurred in late March, followed by gamma-ray activity that declined before the end of the EHT observing period. During this interval, the source remained in a low X-ray state and showed no detectable VHE emission. The TEMZ modeling suggests that the broadband spectrum and variability of 3C 279 can be explained within a jet scenario in which turbulent plasma cells are compressed by a stationary conical shock. However, alternative interpretations, such as magnetic reconnection or a moving shock-in-jet event, remain plausible. This coordinated MWL campaign advances our understanding of the origin of jet and gamma-ray emission in 3C 279, while also providing a comprehensive publicly available dataset that will serve as a valuable reference for future studies.
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All authors G. Principe, J. C. Algaba, E. Aviano, W.Y. Cheong, K. Hada, D. Haggard, A. Hahn, S.G. Jorstad, E. V. Kravchenko, Y. Kovalev, S.S. Lee, M. Lisakov, S. Markoff, A.P. Marscher, M. Sasada, P. Voitsik, Kazunori Akiyama, Ezequiel Albentosa-Ruiz, Antxon Alberdi, Walter Alef, Richard Anantua, Eleni Antonopoulou, Keiichi Asada, Rebecca Azulay, Anne-Kathrin Baczko, David Ball, Bidisha Bandyopadhyay, John Barrett, Michi Baubock, Bradford A. Benson, Dan Bintley, Lindy Blackburn, Raymond Blundell, Katherine L. Bouman, Geoffrey C. Bower, Michael Bremer, Roger Brissenden, Silke Britzen, Avery E. Broderick, Dominique Broguiere, Thomas Bronzwaer, Sandra Bustamante, Douglas F. Carlos, John E. Carlstrom, Andrew Chael, Chi-kwan Chan, Dominic O. Chang, Koushik Chatterjee, Ming-Tang Chen, Yongjun Chen, Xiaopeng Cheng, Paul Chichura, Ilje Cho, Nicholas S. Conroy, John E. Conway, Thomas M. Crawford, Geoffrey B. Crew, Alejandro Cruz-Osorio, Yuzhu Cui, Brandon Curd, Rohan Dahale, Jordy Davelaar, Joost de Kleuver, Mariafelicia De Laurentis, Roger Deane, Jason Dexter, Vedant Dhruv, Indu K. Dihingia, Sheperd S. Doeleman, Sergio A. Dzib, Razieh Emami, Heino Falcke, Joseph Farah, Vincent L. Fish, Edward Fomalont, H. Alyson Ford, Marianna Foschi, Raquel Fraga-Encinas, William T. Freeman, Per Friberg, Christian M. Fromm, Antonio Fuentes, Peter Galison, Charles F. Gammie, Roberto Garcia, Olivier Gentaz, Boris Georgiev, Ciriaco Goddi, Roman Gold, Arturo I. Gomez-Ruiz, Jose L. Gomez, Minfeng Gu, Mark Gurwell, Ronald Hesper, Dirk Heumann, Luis C. Ho, Paul Ho, Mareki Honma, Chih-Wei L. Huang, Lei Huang, David H. Hughes, Shiro Ikeda, C. M. Violette Impellizzeri, Makoto Inoue, Sara Issaoun, David J. James, Buell T. Jannuzi, Michael Janssen, Britton Jeter, Wu Jiang, Alejandra Jimenez-Rosales, Michael D. Johnson, Adam C. Jones, Abhishek V. Joshi, Taehyun Jung, Tomohisa Kawashima, Garrett K. Keating, Mark Kettenis, Dong-Jin Kim, Jae-Young Kim, Jongsoo Kim, Junhan Kim, Motoki Kino, Jakob Knollmüller, Jun Yi Koay, Prashant Kocherlakota, Yutaro Kofuji, Patrick M. Koch, Shoko Koyama, Carsten Kramer, Joana A. Kramer, Michael Kramer, Thomas P. Krichbaum, Cheng-Yu Kuo, Noemi La Bella, Deokhyeong Lee, Aviad Levis, Shaoliang Li, Zhiyuan Li, Rocco Lico, Greg Lindahl, Michael Lindqvist, Jun Liu, Kuo Liu, Elisabetta Liuzzo, Wen-Ping Lo, Andrei P. Lobanov, Laurent Loinard, Colin J. Lonsdale, Amy E. Lowitz, Ru-Sen Lu, Nicholas R. MacDonald, Jirong Mao, Nicola Marchili, Daniel P. Marrone, Alan P. Marscher, Ivan Marti-Vidal, Satoki Matsushita, Lynn D. Matthews, Lia Medeiros, Karl M. Menten, Hugo Messias, Izumi Mizuno, Yosuke Mizuno, Joshua Montgomery, Kotaro Moriyama, Monika Moscibrodzka, Wanga Mulaudzi, Cornelia Müller, Hendrik Müller, Alejandro Mus, Gibwa Musoke, Ioannis Myserlis, Hiroshi Nagai, Neil M. Nagar, Dhanya G. Nair, Masanori Nakamura, Gopal Narayanan, Iniyan Natarajan, Antonios Nathanail, Santiago Navarro Fuentes, Joey Neilsen, Chunchong Ni, Andy Nilipour, Michael A. Nowak, Hiroki Okino, Hector Ra.l Olivares Sanchez, Feryal Ozel, Daniel C. M. Palumbo, Georgios Filippos Paraschos, Jongho Park, Harriet Parsons, Nimesh Patel, Ue-Li Pen, Dominic W. Pesce, Vincent Pietu, Alexander Plavin, Aleksandar PopStefanija, Oliver Porth, Ben Prather, Dimitrios Psaltis, Hung-Yi Pu, Alexandra Rahlin, Venkatessh Ramakrishnan, Ramprasad Rao, Mark G. Rawlings, Angelo Ricarte, Luca Ricci, Bart Ripperda, Jan Roder, Freek Roelofs, Cristina Romero-Ca.izales, Eduardo Ros, Arash Roshanineshat, Helge Rottmann, Alan L. Roy, Ignacio Ruiz, Chet Ruszczyk, Kazi L. J. Rygl, Leon D. S. Salas, Salvador Sanchez, David Sanchez-Argüelles, Miguel Sanchez-Portal, Ali SaraerToosi, Kaushik Satapathy, Saurabh, Tuomas Savolainen, Karl-Friedrich Schuster, Zhiqiang Shen, Sasikumar Silpa, Randall Smith, Bong Won Sohn, Jason SooHoo, Kamal Souccar, Joshua S. Stanway, He Sun, Alexandra J. Tetarenko, Paul Tiede, Remo P. J. Tilanus, Michael Titus, Kenji Toma, Pablo Torne, Teresa Toscano, Efthalia Traianou, Sascha Trippe, Matthew Turk, Ilse van Bemmel, Bram van den Berg, Huib Jan van Langevelde, Daniel R. van Rossum, Sebastiano D. von Fellenberg, Jesse Vos, Jan Wagner, Zhiren Wang, Derek Ward-Thompson, John Wardle, Jasmin E. Washington, Jonathan Weintroub, Maciek Wielgus, Kaj Wiik, Michael F. Wondrak, George N. Wong, Jompoj Wongphexhauxsorn, Qingwen Wu, Paul Yamaguchi, Aristomenis Yfantis, Doosoo Yoon, Andre Young, Ziri Younsi, Wei Yu, Feng Yuan, Ye-Fei Yuan, Ai-Ling Zeng, J. Anton Zensus, Shuo Zhang, Guang-Yao Zhao, J. Abhir, A. Abhishek, V. A. Acciari, A. Aguasca-Cabot, I. Agudo, I. Albanese, T. Aniello, S. Ansoldi, L. A. Antonelli, A. Arbet Engels, C. Arcaro, T. T. H. Arnesen, A. Babic, C. Bakshi, U. Barres de Almeida, J. A. Barrio, L. Barrios-Jimenez, I. Batkovic, J. Becerra Gonz.lez, W. Bednarek, E. Bernardini, J. Bernete, A. Berti, J. Besenrieder, C. Bigongiari, A. Biland, O. Blanch, G. Bonnoli, Ž. Bošnjak, E. Bronzini, I. Burelli, A. Campoy-Ordaz, A. Carosi, R. Carosi, M. Carretero-Castrillo, A. J. Castro-Tirado, D. Cerasole, G. Ceribella, A. Cervi.o, Y. Chai, G. Chon, J. L. Contreras, J. Cortina, S. Covino, P. Da Vela, F. Dazzi, A. De Angelis, B. De Lotto, M. Delfino, J. Delgado, C. Delgado Mendez, F. Di Pierro, R. Di Tria, L. Di Venere, A. Dinesh, D. Dominis Prester, A. Donini, D. Dorner, M. Doro, L. Eisenberger, D. Elsaesser, L. Foffano, L. Font, F. Fr.as Garcia-Lago, S. Fr.se, Y. Fukazawa, S. Gasparyan, M. Gaug, J. G. Giesbrecht Paiva, N. Giglietto, F. Giordano, P. Gliwny, T. Gradetzke, R. Grau, J. G. Green, P. Günther, D. Hadasch, G. Harutyunyan, J. Herrera Llorente, D. Hrupec, D. Israyelyan, J. Jahanvi, I. Jimenez Martinez, J. Jimenez Quiles, S. Kankkunen, T. Kayanoki, J. Konrad, P. M. Kouch, H. Kubo, J. Kushida, M. L.inez, A. Lamastra, E. Lindfors, S. Lombardi, F. Longo, R. Lopez-Coto, M. Lopez-Moya, A. Lopez-Oramas, S. Loporchio, L. LuliLc, P. Majumdar, M. Makariev, M. Mallamaci, G. Maneva, M. Manganaro, S. Mangano, K. Mannheim, S. Marchesi, M. Mariotti, M. Martinez, P. Maruševec, D. Mazin, S. Menchiari, J. M.ndez Gallego, S. Menon, D. Miceli, J. M. Miranda, R. Mirzoyan, M. Molero Gonzalez, E. Molina, H. A. Mondal, A. Moralejo, C. Nanci, A. Negro, V. Neustroev, C. Nigro, L. Nikolic, K. Noda, S. Nozaki, A. Okumura, J. Otero-Santos, S. Paiano, D. Paneque, R. Paoletti, J. M. Paredes, M. Peresano, M. Persic, M. Pihet, G. Pirola, F. Podobnik, P. G. Prada Moroni, E. Prandini, M. Rib., J. Rico, A. Roy, N. Sahakyan, F. G. Saturni, F. Schiavone, K. Schmitz, A. Sciaccaluga, G. Silvestri, A. Simongini, J. Sitarek, V. Sliusar, D. Sobczynska, A. Stamerra, J. Striškovic, D. Strom, Y. Suda, M. Takahashi, R. Takeishi, J. Tartera Barber., P. Temnikov, T. Terzic, M. Teshima, A. Tutone, S. Ubach, S. Ventura, G. Verna, I. Viale, A. Vigliano, C. F. Vigorito, E. Visentin, V. Vitale, M. Vorbrugg, I. Vovk, R. Walter, C. Walther, F. Wersig, P. K. H. Yeung, A. Acharyya, F. Aharonian, H. Ashkar, M. Backes, M. Barnard, Y. Becherini, M. B.ttcher, J. Bolmont, B. Bruno, T. Bylund, S. Casanova, M. Chernyakova, J. O. Chibueze, O. Chibueze, B. Cornejo, J. Damascene Mbarubucyeye, I.D. Davids, J. de Assis Scarpin, M. de Naurois, A. Dmytriiev, K. Egberts, S. Fegan, K. Feijen, M. D. Filipovic, G. Fontaine, S. Gabici, J.F. Glicenstein, P. Goswami, L. Heckmann, B. He., M. Holler, D. Horns, E. Kasai, K. Katarzynski, D. Kerszberg, B. Kh.lifi, K. Kosack, R.G. Lang, S. Lazarevic, P. Liniewicz, A. Luashvili, D. Malyshev, D. Malyshev, M. G. F. Mayer, M. Meyer, A. Mikhno, E. Moulin, H. Ndiyavala, J. Niemiec, P. Pichard, T. Preis, G. Pühlhofer, A. Quirrenbach, A. Reimer, O. Reimer, I. Reis, B. Rudak, K. Sabri, V. Sahakian, A. Santangelo, M. Sasaki, I. Shebalkova, W. Si Said, L. Stawarz, R. Steenkamp, T. Tanaka, G. L. Taylor, R. Terrier, Y. Tian, M. Tluczykont, C. Venter, J. Vink, V. Voitsekhovskyi, S.J. Wagner, A. Wierzcholska, M. Zacharias, A.A. Zdziarski

Superconductivity

First-Principles Quantum-Spectral framework for Elementary Vortex Pinning in superconductors

Haozhe Shi, Yuncheng Xie, Tong Zhang et al. (+2 more)

The critical current of a type-II superconductor is controlled by vortex pinning, whose microscopic input is the elementary pinning force. Scanning tunneling spectroscopy has shown that a defect pins a vortex by reorganizing the Caroli–de Gennes–Matricon (CdGM) states in its core, but why this spectral reorganization amounts to a pinning force has lacked a quantum-mechanical, first-principles account. Here we establish a transferable first-principles computational framework for elementary vortex pinning, in which defect-resolved DFT/Wannier electronic structures are embedded into a finite-box projected Bogoliubov–de Gennes free-energy formalism to convert quasiparticle spectral reorganization into vortex-pinning energies and forces. Using this framework, we confirm that the defect-induced reorganization of the vortex-core spectrum is the microscopic origin of the elementary pinning force. The force is evaluated as a finite-box vortex-insertion free energy whose four-configuration subtraction isolates the meV-scale interaction from much larger backgrounds. With the superconducting gap scale and vortex-core profile fixed from experiments, the FeSe Fe-site vacancy reproduces the microscopic STM force scale together with the measured spectral reorganization. All five point defects in FeSe and FeTe pin attractively, with FeTe Fe-site vacancy strongest. Elementary vortex pinning thereby becomes a computable electronic-structure quantity, opening the first-principles screening of point defects toward higher critical currents.
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All authors Haozhe Shi, Yuncheng Xie, Tong Zhang, Weibin Chu, Xin-Gao Gong

Materials Science

Sensitivity-optimal coplanar waveguide design for broadband magnetic resonance spectroscopy: a Beer–Lambert framework

Scott Dietrich and Artur Solodovnyk

Coplanar waveguide (CPW) transmission spectroscopy is used to probe spin dynamics, ferromagnetic resonance, and complex conductivity across a wide range of materials, yet no systematic framework connects waveguide geometry to measurement sensitivity when sample volume and concentration are fixed. We show that the shared geometric scaling of sample coupling and conductor loss maps CPW design onto the Beer–Lambert optimization problem of optical spectrophotometry, reducing it to a universal one-parameter problem whose solution depends only on sample geometry and the dominant noise source – not on sample properties, operating frequency, or system losses. The framework predicts a near-universal $1\,\mathrm{Np}$ optimum across the full range of sample thicknesses and design geometries. Benchmarking against seven published broadband FMR instruments reveals two fabrication-delimited classes: PCB-milled designs are bounded by a ceiling imposed by their minimum slot width, while photolithographic designs approach the additive-noise optimum. For large-area PCB samples a meander geometry offers a direct path to near-optimal sensitivity without interferometric compensation; for sub-millimeter samples, a single lithographic straight pass suffices.
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Quantum Physics

Nonlinear Dynamics of Coherent Parametric Amplification in Multipartite two-level System under Intrinsic Decoherence

Muhammad Ibrahim

In this work, we study the dynamics of global quantum discord and quantum Fisher information in a multipartite system of two-level atoms interacting with a coherent field. The model includes parametric amplification, Kerr-type nonlinearity, and intrinsic decoherence to examine how these effects control quantum correlations and parameter-estimation sensitivity. The results show that, without intrinsic decoherence, both quantities exhibit rapid oscillations with clear collapse and revival behavior. Strong Kerr nonlinearity and strong parametric amplification enhance global quantum discord, while quantum Fisher information becomes maximum under a suitable balance of Kerr nonlinearity and amplification strength. Increasing the number of atoms generally strengthens global quantum discord but does not always improve quantum Fisher information. Intrinsic decoherence damps the oscillations and drives the system toward steady-state behavior.
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Astrophysics of Galaxies

JWST resolves jet-driven H2 and ionized outflows in radio galaxy 3C305

B. Sebastian, P. M. Ogle, P. Guillard et al. (+17 more)

We present JWST MIRI MRS, NIRSpec, NIRCam, and MIRI imaging observations of 3C 305, a radio galaxy with a compact jet that is confined within the galaxy. We use the H2 0-0 S(1)-S(7) lines, several mid-IR fine-structure lines, and PAH emission in the MIRI MRS spectrum to conduct a multiphase study of the radio jet's impact on the interstellar medium. Multiple tracers, including H2/PAH 11.3 um and [Fe II] 5.34 um, provide evidence for shocks at the jet termination locations. Two Gaussian components are required to reproduce the warm H2 kinematics adequately, with one representing the bulk low-velocity component and the other corresponding to an outflow. The ionized gas reaches higher outflow velocities than the H2 gas, and the sharp increase in velocity at the jet hotspots points to jet-driven outflows. We fit the H2 excitation diagram with a power-law temperature distribution and find that the hotspots exhibit flatter slopes, indicating a larger warm/hot gas mass fraction at these locations. Our MAPPINGS line-ratio analysis indicates that most of the mid-IR ionized gas can be fit by a shock-plus-precursor model. We find that strong radiative losses dominated by line cooling, together with moderate kinetic power in the molecular and ionized gas outflows, can account for the estimated jet power, indicating high jet coupling efficiency in 3C 305. Together with other studies of multiphase gas, our results show that jets can efficiently shock-heat and accelerate the gas they encounter, driving massive, kiloparsec-scale, multiphase outflows.
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All authors B. Sebastian, P. M. Ogle, P. Guillard, L. Lanz, R. Morganti, V. Reynaldi, I. E. Lopez, B. Emonts, S. Garcia-Burillo, C. Tadhunter, C. P. O'Dea, S. Baum, F. R. Faifer, A. Labiano, M. Lehnert, A. Togi, K. Alatalo, P. Appleton, R. Bhutkar, E. Egami

Optics

Hybrid deep learning-based phase diversity method for wavefront reconstruction

Y. Rodimkov, A. Kotov, K. Burdonov et al. (+4 more)

The efficiency of high-power laser systems is limited by wavefront distortions in the beam, particularly non-common path aberrations, which reduce the peak intensity at the focal plane. Compensating for these aberrations requires the calibration of the adaptive optics system. Conventional calibration methods rely on a time-consuming iterative optimization that is highly sensitive to initial conditions. While deep learning-based models offer high speed, they often demonstrate insufficient accuracy. In this work, we present a hybrid wavefront reconstruction method that combines a convolutional neural network to generate an initial estimate of the wavefront distortions, with the L-BFGS (Limited-memory Broyden-Fletcher-Goldfarb-Shanno) algorithm for its subsequent refinement. In numerical simulations, the method achieved an efficiency of $\sim 0.99$ in 80% of the cases for a root-mean-square (RMS) of wavefront distortions ranging from 0 to $1.3\lambda$. In a physical experiment, for initial wavefront distortions with RMS values from 0.15 to $0.6\lambda$, the method achieved an efficiency of $\sim 0.75$. As a result, focusing with a Strehl ratio of $0.96 \pm 0.02$ was attained within 2 to 4 iterations of the algorithm, confirming the applicability of the method for the fast and accurate calibration of adaptive optics systems under real experimental conditions.
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All authors Y. Rodimkov, A. Kotov, K. Burdonov, S. Perevalov, V. Volokitin, I. Meyerov, A. Soloviev

Materials Science

A Combined Tight Binding with Machine Learning Potential Model for Magnesium Compounds

Jiwen Yu, Arash A. Mostofi and Andrew Horsfield

We present a model for magnesium-based systems that combines density functional tight binding (DFTB) with MACE, a machine learning interatomic potential (DFTB+MACE). In this model, the conventional repulsive potential, pair potential, is replaced by a many-body MACE potential. The MACE component of the model is trained on the difference between density functional theory (DFT) energies and forces and the corresponding DFTB values, but neglecting the pair potential contribution. Using this model we performed structural relaxation of MgO-CO2 adsorption systems, molecular dynamics calculations of water clusters and phonon spectrum calculations of stable fcc-MgO and metastable bcc-MgO structures. We compare the performance of our model with a pure MACE model and with DFT. We demonstrate that the DFTB+MACE model achieves improved accuracy relative to DFTB with a pair potential, in many cases with only a moderate increase in computational cost. In addition, it can provide electronic structures that most of the machine learning potentials cannot. The training dataset, originally developed for MACE, may not fully represent all regions of the potential surface we may encounter during simulations. Expanding the dataset for a wider potential surface is expected to further enhance predictive accuracy of DFTB+MACE model. Overall, the resulting DFTB+MACE framework enables simulations at length and time scales beyond the reach of first-principles methods while retaining an explicit description of electronic structures, making it particularly attractive for studying charge-transfer in materials.
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Materials Science

Harnessing electrostatics through temperature modulations to control ferroelectrics

Cameron A.M. Scott, Xabier Diaz de Cerio and Jorge Íñiguez-González

Temperature modulations provide an alternative method for dynamically controlling the ferroelectric state. In this paper, we use scale-independent Landau potentials and predictive atomistic simulations to explore how temperature modulation can harness the depolarizing field to obtain non-electrical poling. We further predict that temperature gradients can be combined with strain to induce persistent polar textures such as multidomain states.
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Atomic Physics

Collisions and Stopping of Fast Charged Particles in Matter

Francesc Salvat

This text is intended to offer a consistent presentation of the theory of collisions and stopping of charged particles in matter, limited to the range of intermediate kinetic energies where atomic aggregation effects are relatively unimportant and processes such as the creation of particle-antiparticle pairs are not likely to occur. The first three Chapters contain introductory material on the classical description of electromagnetic fields in matter, an overview of quantum wave equations for a particle in a central potential, and an account of elementary atomic-structure models. Chapters 4 and 5 are devoted to the classical and quantum theories of elastic collisions of charged particles with atoms. The theory of inelastic collisions and stopping is split into two parts: first, collisions with atoms are considered within the plane-wave Born approximation in Chapter 6, which includes a derivation of the Bethe stopping power formula; second, the theory of inelastic collisions in dense materials is based on the dielectric formalism, which is formulated for the electron gas, and extended to arbitrary materials by means of optical-data models in Chapter 7. Chapter 8 offers a detailed review of the theory of stopping, starting with the classical study by Bohr and ending with derivations of the Bloch and Barkas corrections to the stopping power. Chapter 9 deals with general aspects of transport theory, including derivations of energy-straggling distributions and multiple-scattering distributions, which are the basis for condensed simulation schemes of charged particle transport. Finally, Chapter 10 describes the Fortran programs elastic and sbethe, which implement the main theoretical models presented in the preceding Chapters and are distributed as ancillary information.
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Exactly Solvable and Integrable Systems

Tri-Hamiltonian structure of an asymmetric generalized Ablowitz-Ladik hierarchy and a Frobenius manifold

Hanxue Zhang, Qiulan Zhao and Xinyue Li

We construct a local tri-Hamiltonian structure of the asymmetric (3,1)-type generalized Ablowitz-Ladik (gAL) hierarchy at the full-dispersive level and rigorously prove its validity using the supervariable technique. All central invariants of the corresponding bi-Hamiltonian structures are computed. In addition, we construct a Frobenius manifold M arising from the dispersionless limit of this hierarchy and show that the dispersionless limits of the first flows of the (3,1)-type gAL hierarchy belong to the Principal Hierarchy of M.
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Cosmology and Nongalactic Astrophysics

Probing Kinematic Anisotropies in the Stochastic Gravitational Wave Background with the SKA

N. M. J. Cruz, Ameek Malhotra, Gianmassimo Tasinato et al. (+1 more)

Pulsar Timing Arrays (PTAs) and astrometric surveys provide complementary probes of the nanohertz stochastic gravitational-wave background (SGWB). A primary target is the kinematic dipole induced by the Solar System's motion, whose detection would confirm the SGWB's cosmological origin. We forecast the sensitivity of the Square Kilometre Array Observatory (SKAO) using optimal estimators and Fisher techniques, considering both the baseline AA4 configuration and an optimistic 1000 pulsar scenario, including the potential gain from combining with Gaia-like astrometry. While SKAO will substantially improve constraints on SGWB anisotropies, even joint analyses remain below the sensitivity required to detect the kinematic dipole, motivating new observational and analysis strategies to fully exploit this signal.
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All authors N. M. J. Cruz, Ameek Malhotra, Gianmassimo Tasinato, Ivonne Zavala

Materials Science

Spontaneous spin splitting and tunable valley polarization in a two-dimensional fully compensated ferrimagnet

Hongyan Lv, Yueli Li, Yunfan Zhang et al. (+3 more)

Materials with controllable valley polarization and anomalous valley Hall (AVH) effect are highly desired in valleytronic applications. While current AVH studies primarily focus on ferromagnetic materials, two-dimensional (2D) antiferromagnets are more attractive for valleytronics since they possess zero net magnetization, negligible stray fields, and ultrafast spin dynamics. Nevertheless, the joint space-inversion and time-reversal ($PT$) symmetry in conventional collinear antiferromagnets prohibits the occurrence of AVH response. The recently proposed fully compensated ferrimagnets break $PT$ symmetry, and the spin-opposite sublattices are not related by crystal symmetry, providing a natural platform for the coexistence of spontaneous spin splitting, valley polarization, and anomalous-Hall compatible symmetry. Herein, we demonstrate that such compensated ferrimagnetism can be realized in a Janus Mn$_{2}$BrI monolayer, with a Néel temperature above room temperature. Spontaneous spin splitting is observed due to the built-in layer-dependent electrostatic potential. When SOC is considered, valley polarization emerges for an out-of-plane Néel vector. Moreover, proper hole doping stabilizes the perpendicular magnetic anisotropy and the two valleys exhibit markedly different Berry curvatures, thereby making AHE responses allowed. Furthermore, the valence band extrema of Mn$_{2}$BrI monolayer can be effectively tuned by external biaxial strain and giant piezomagnetism can be achieved. Our results identify Janus Mn$_{2}$BrI monolayer as a promising fully compensated ferrimagnetic platform for 2D valleytronics and spintronics.
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All authors Hongyan Lv, Yueli Li, Yunfan Zhang, Jiayu Dai, Zhongjun Li, Ding-Fu Shao

High Energy Physics (Experiment)

Search for long-lived particles decaying into muons in proton-proton collisions at $\sqrt{s}$ = 13.6 TeV using data scouting

CMS Collaboration

A search for long-lived particles decaying into muons is performed using proton-proton collisions at $\sqrt{s}$ = 13.6 TeV, collected by the CMS experiment at the LHC in 2022 and 2023, corresponding to an integrated luminosity of 62.4 fb$^{-1}$. The data were collected using dedicated dimuon triggers with low transverse momentum thresholds, recorded with a high-rate data scouting trigger stream. This data stream retains a reduced amount of information at the high-level trigger, to explore otherwise inaccessible phase space at low multimuon invariant mass and nonzero displacement from the primary interaction vertex. No significant excess of events above the standard model prediction is found. Upper limits on branching fractions at 95% confidence level are set for a wide range of mass and lifetime hypotheses in several beyond the standard model frameworks, where the Higgs boson decays into long-lived dark photons or into dark partons that produce showers containing long-lived particles, or where a long-lived scalar resonance is produced from the decay of a b hadron. The resulting constraints improve and extend existing ones in large regions of the parameter space.
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Other Condensed Matter

Brillouin Light Scattering Spectroscopy of Propagating Magnons at Sub-Kelvin Temperatures

David Schmoll, Nikolai Kuznetsov, Phillip Rehberger et al. (+8 more)

Coupling light to magnetic excitations in the form of spin waves underpins both the optical study of magnetism and emerging schemes for quantum transduction, positioning the quanta of these excitations, magnons, as promising carriers for hybrid quantum networks. However, exploiting them in the quantum regime requires millikelvin temperatures to suppress thermal magnon populations, thereby confining such experiments to dilution refrigerators. There, magnons can already be excited and read out electrically, yet an optical interface required for microwave-to-optical photon conversion has been missing. Here, we demonstrate the first optical detection of coherently driven, propagating spin waves via Brillouin Light Scattering (BLS) spectroscopy inside a dilution refrigerator. By simultaneously recording the optical and electrical responses of the same spin-wave mode in a yttrium iron garnet film, we find that the BLS spectra track the electrically measured transmission across a range of applied magnetic fields. For the lowest optical power of 7.9 {\mu}W that still enabled spin-wave detection, we measured a global equilibrium sample temperature of 510 mK via a resistance thermometer, while numerical modelling of the laser-induced heating yields a maximum local temperature of 900 mK at the focal spot. This brings free-space optical access to magnons into the sub-kelvin regime, representing a milestone towards magnon-mediated quantum transduction in hybrid quantum systems.
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All authors David Schmoll, Nikolai Kuznetsov, Phillip Rehberger, Franz Vilsmeier, Roman Verba, Denys Slobodianiuk, Rostyslav O. Serha, Khrystyna O. Levchenko, Sebastiaan van Dijken, Andrii V. Chumak, Sebastian Knauer

High Energy Astrophysical Phenomena

Hybrid radio and particle detection of air showers: potential for ultra-high-energy photon identification

Paul Minodier, Kaoru Takahashi, Kumiko Kotera et al. (+1 more)

The autonomous radio-detection of extensive air showers initiated by ultra-high-energy (UHE) particles arriving with very inclined zenith angles has seen significant advancements in recent years, with several large-scale surface arrays planned and prototypes already in operation. In this work, we examine whether these radio detectors, supplemented by scintillators, could serve as competitive UHE photon detectors. Indeed, for inclined showers, radio emissions can be detected by antennas for both cosmic-ray and photon primaries, while the muon-rich signatures of the former would typically trigger the scintillators. Using two key observables – the total root mean square of the radio signal and the total energy deposit recorded in the scintillators – we show that effective separation between the two types of showers could be achieved in a hybrid radio antenna and scintillator setup. As a case study, we apply this method to a hypothetical hybrid array of radio antennas, complemented by Telescope Array-like scintillators, with the layout of the prototype of the Giant Radio Array for Neutrino Detection (GRAND), GRANDProto300. Our estimates show that such a hybrid array could set competitive upper limits on the integral photon flux in the energy range of approximately 0.3 to 3 EeV.
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All authors Paul Minodier, Kaoru Takahashi, Kumiko Kotera, Takashi Sako

Astrophysics of Galaxies

Impact of Anomalous Microwave Emission (AME) on Radio Spectral Energy Distributions: SKA Observations of Galaxies Near and Far

Ilsang Yoon, Eric Murphy, Caroline Bot et al. (+1 more)

Radio continuum emission powered by the thermal bremsstrahlung process is a clean, dust-free tracer of star formation in galaxies. However, the existence of anomalous microwave emission (AME) that is also prominent in a similar frequency range may challenge the use of thermal radio continuum emission to measure the star formation rates of galaxies. So while the nature of AME and the ISM conditions that lead to strong observable AME are still not well understood, the impact of AME on the radio emission from galaxies needs to be investigated for the SKA, which will be sensitive to large numbers of faint, high-redshift galaxies. In this chapter, we compute the observable flux density of free-free emission and AME and investigate the impact of AME on the galaxy radio spectral energy distribution for given observing frequencies and redshifts. Our conclusion is that (1) significance of AME is determined by the size of the AME region relative to the observing beam and ISM hydrogen column density, (2) thermal free-free emission dominates the radio continuum emission for distant galaxies at $\approx 10$ GHz frequency with negligible contribution from AME, (3) high-angular resolution observation of nearby galaxies resolving individual star forming region may need multi-frequency observations to avoid a potential bias from AME in the measure of star formation rate from single frequency observation.
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All authors Ilsang Yoon, Eric Murphy, Caroline Bot, Lucie Correia

Atomic Physics

Coupling of negative-positive trapped-ion pairs

Daniel Kienzler

Direct motional coupling of opposite-charge trapped-ion pairs could provide a pathway to extend ultra-low temperatures and quantum control to negative ions that lack the suitable electronic energy structures required for direct laser cooling. Because positive and negative ions cannot be confined within a single electrostatic potential well, I investigate a configuration where single ions are trapped in close proximity within separate potential wells to couple their motion. I analytically and numerically evaluate the electrostatic trapping requirements. As a concrete implementation, I present an optimized segmented surface Paul trap design to couple an antimatter hydrogen molecular ion ($\bar{H}_2^-$) and a beryllium ion ($^9 Be^+$). A motional coupling frequency of 5 kHz can be achieved at an ion-ion separation of $35 \mu m$, with an ion height of $50 \mu m$, axial trap frequencies of 4 MHz, and static trap voltages with a magnitude of $\approx 20 V$. Finally, I outline three applications for this technique: quantum logic spectroscopy of $\bar{H}_2^-$ for matter-antimatter comparisons, the preparation of cold neutral deuterium atoms via near-threshold photo-detachment of $D^-$ for optical trapping, and quantum information processing using equal-mass opposite-charge ion pairs.
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