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Physics

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Tuesday 16 June

Chemical Physics

Constrained Optimization Algorithms for Orbital Optimization in Quantum Chemistry

Junzhe Zhang, Shuoyi Hu and Bing Gu

We present a modular constrained-orbital-optimization framework for quantum chemistry. The formulation separates the correlated electronic-structure solver from the orbital optimizer: the solver supplies one- and two-particle reduced density matrices, while the molecular orbitals are updated on the orthonormality-constrained Stiefel manifold with an implicit steepest-descent algorithm. Because the orbital optimizer only requires reduced density matrices, MP2, CASCI, and DMRG can be treated within the same interface. For CASCI solvers, the approach is closely related to optimal-orbital full configuration interaction and CASSCF\cite{helgaker_MulticonfigurationalSelfConsistentField_2000a}, but uses a solver-independent constrained-optimization update rather than CAS-specific orbital-rotation equations. When conventional CASSCF orbital-rotation iterations converge to higher-energy local solutions, CO-CAS can recover lower-energy stationary solutions. We also introduce a modified direct inversion in the iterative subspace procedure to accelerate macro-iteration convergence and a dynamical-weighting scheme to improve state-averaged excited-state calculations. Applications to LiF, H$_2$O, and pyrazine show that orbital optimization lowers energies relative to fixed-orbital MP2, CASCI, and DMRG references while improving convergence and potential-energy-curve smoothness.
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Nuclear Experiment

Measurement of isolated photon plus two-jet correlations in Pb+Pb and $pp$ collisions at 5.02 TeV with ATLAS

ATLAS Collaboration

This paper presents a measurement of photon plus two-jet events in $pp$ and Pb+Pb collisions, i.e. events in which the transverse momentum of a single photon is balanced by two distinct jets. The measurement was performed using $pp$ data taken in 2017 with an integrated luminosity 260 pb$^{-1}$, and Pb+Pb data taken in 2018 with an integrated luminosity 1.72 nb$^{-1}$, both at $\sqrt{s_\mathrm{NN}}$ =5.02 TeV, as recorded by the ATLAS detector. Events with photons in the transverse momentum range 90-180 GeV and at least two anti-$k_t$ $R = 0.2$ jets with a $p_\mathrm{T}$ > 30 GeV are selected, and three observables are measured: ${\mathrm{x}}_{\mathrm{JJ}\gamma}$, $\mathrm{A}_{\mathrm{JJ}\gamma}$, and $\Delta R_{\mathrm{JJ}}$. These observables characterise the overall energy loss of the multiparton system from medium interactions (${\mathrm{x}}_{\mathrm{JJ}\gamma}$), the relative energy loss between the two colour-charge carriers ($\mathrm{A}_{\mathrm{JJ}\gamma}$), and medium-induced modifications to their opening angle ($\Delta R_{\mathrm{JJ}}$). The observables are corrected for uncorrelated combinatoric background contributions using a novel multijet mixing technique, for photon purity, and for detector resolution effects via iterative unfolding. Final results are presented per photon, and the ratio ($I_\mathrm{AA}$) is taken between measurements in Pb+Pb and $pp$ collisions, for Pb+Pb centrality intervals of 30-80%, 10-30%, and 0-10%. Significant suppression of per photon two-jet yields in all three observables, $I_\mathrm{AA} < 1$, is observed as a result of parton-medium interactions. The experimental measurements are compared to three different jet quenching models: JEWEL, JETSCAPE, and LBT.
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High Energy Physics (Theory)

A Double–Scaling Large–\(d\) Saddle of BFSS/BMN Matrix Quantum Mechanics

Badis Ydri

We study the large–\(d\) dynamics of the mass–deformed bosonic \(\mathrm{BFSS}_{d+1}\) matrix quantum mechanics using a Hubbard–Stratonovich localization of the Yang–Mills interaction. After integrating out the matrix coordinates, the theory reduces to a holonomy–dependent effective action for an auxiliary adjoint kernel. We introduce a commuting–symmetric saddle and its maximally symmetric specialization, in which the interaction is encoded in a single dynamically generated mass shift \(k_0\). The resulting large–\(d\) description is a gauged matrix harmonic oscillator with self–consistent frequency \(s^2=m+k_0\), fixed by a gap equation. We analyze the low–temperature \(X\)-space physics, the holonomy effective action, the Yang–Mills observable, and the associated phase structure. We then identify a correlated double–scaling limit in which \(d\to\infty\), \(m\to\infty\), and \(\kappa=m^{3/2}/d\) is held fixed. In this limit the Yang–Mills interaction and the explicit mass deformation remain parametrically balanced: the theory interpolates between the commutator–dominated BFSS regime and the mass–dominated Gaussian regime. The double–scaled theory exhibits two complementary large–\(d\) regimes. At low temperature, the enhanced gap pushes the deconfinement scale upward and opens a parametrically large uniform–holonomy region, where the bulk dynamics behaves as weakly coupled \(\mathrm{BFSS}_2\)–type gauged harmonic–oscillator sectors. At the same time, the high–temperature branch reveals an overlap window in which the Gaussian description remains self–consistent while the commutator contribution per matrix pair is parametrically suppressed. The resulting dynamics is therefore \(\mathrm{BFSS}_2\)–like in its enlarged uniform–holonomy sector and IKKT–like in its almost–commuting matrix behavior.
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2606.17758 · 16 Jun · Accepted for publication in IJMPA. Sections 1.3, 6.3, and 8.4 and Appendices B and C, including the associated Monte Carlo figures, were removed; Sections 3.3, 5.6, and 7.4 were added; Sections 4.3, 4.6, and 8.3 were revised; and one figure, 14 references, and technical corrections were added. This is the first part of the two-decade "BFSS/BMN Matrix Quantum Mechanics" study

Abstract PDF $MTRX ×6$QNTM ×2

Astrophysics of Galaxies

Tracing the very early disruption of the Sagittarius dwarf galaxy in the distant Milky Way halo

Manuel Bayer, Else Starkenburg, Akshara Viswanathan et al. (+3 more)

Current models predict that at distances beyond 80 kpc in the Milky Way halo, we can find the earliest escaped stars from the merging Sagittarius dwarf galaxy. However, observational data on the Sagittarius stream at these distances is limited. This study examines an overdensity of red giant branch (RGB) stars potentially linked to Sagittarius merger debris. Using the Magellan Inamori Kyocera Echelle spectrograph of Las Campanas Observatory's Clay Telescope, we measured the radial velocities and metallicities of these stars. We compared their properties with model predictions of Sagittarius' disruption and other stellar tracers from the Dark Energy Spectroscopic Instrument Data Release 1 and RR Lyrae catalogs. Our spectral analysis confirms the significant tight clustering of four of these RGBs in full 6D phase space. This tight clump is embedded within a larger spur-like feature of the Sagittarius stream in the southern sky. A comparison with Sagittarius stream models further strengthens this hypothesis and shows that this far spur could be composed of stars originally in the halo of the Sagittarius dwarf galaxy, stripped in the earliest phases of the interaction. The metallicity dispersion of the four stars of $0.15 ^ {+0.17} _ {-0.08}$ around the average of [Fe/H] = $-1.46 ^ {+0.11} _ {-0.09}$ is very low. This study provides the first spectroscopic view of the distant southern spur of Sagittarius, composed of stars likely stripped from Sagittarius's halo.
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All authors Manuel Bayer, Else Starkenburg, Akshara Viswanathan, Vedant Chandra, Alexander P. Ji, Guillaume F. Thomas

Mesoscale and Nanoscale Physics

Effect of inter-edge interaction in a quantum Hall collider

Amulya Ratnakar, Flavio Ronetti, Benoît Grémaud et al. (+4 more)

Fractional quantum Hall (FQH) colliders measure anyon exchange phases via time-domain braiding, but the $\nu=2/5$ state exhibits an intriguing negative Fano factor, challenging theoretical predictions. Here, we study the effect of inter-edge interactions in a multi-mode FQH collider. We demonstrate that the resulting fractionalization into eigenmodes causes the anyon beam to decompose into correlated and uncorrelated components, which have very distinct behavior in terms of time-domain braiding. We show that the uncorrelated part dominates in the long-junction limit, reversing the tunneling current sign and reproducing the observed negative Fano factor at $\nu=2/5$. Our results highlight the role of interactions and provide a robust interpretation of anyonic braiding in multi-mode systems.
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All authors Amulya Ratnakar, Flavio Ronetti, Benoît Grémaud, Laurent Raymond, Thierry Martin, Thibaut Jonckheere, Jérôme Rech

General Relativity and Quantum Cosmology

Intrinsic handedness in O1-O4a black-hole mergers: probing orbital precession, remnant retention in dense environments and cosmological mirror asymmetry

Juan Calderón Bustillo, Adrián del Rio, Nicolás Sanchis-Gual et al. (+1 more)

Precessing binary black-holes generically produce an imbalance of right- and left- handed gravitational waves, reflecting the breaking of mirror symmetry by the merger dynamics. We study this phenomenon using the observer-independent quantity $V_{\rm GW}$, a gravitational analogue of the optical Stokes parameter that quantifies the intrinsic handedness of the emitted radiation. Using 91 LIGO-Virgo-KAGRA black-hole mergers from the O1-O4a observing runs, we find that $92\%$ of the analyzed events favour non-vanishing $V_{\rm GW}$, indicating a predominance of precessing dynamics across the events. Through a recently established relation between $V_{\rm GW}$ and the remnant black hole recoil, we further constrain the retention of merger remnants in dense stellar environments, finding that at most $8\%$ could remain gravitationally bound to globular or nuclear star clusters and subsequently participate in hierarchical merger channels. We finally investigate the cosmological distribution of black-hole merger handedness. The observed $V_{\rm GW}$ distribution is consistent with symmetry under $V_{\rm GW}\rightarrow -V_{\rm GW}$, and yields an average value $\langle V_{\rm GW}\rangle=-1.9^{+6.1}_{-6.6}\times10^{-3}$ ($90\%$ credibility), consistent with the absence of a preferred handedness and with expectations from large-scale statistical isotropy. In particular, the inclusion of O4a events reduces uncertainties in $\langle V_{\rm GW} \rangle$ by $\sim 40\%$ with respect to O1-O3 events. These results establish black-hole merger handedness as a unified probe of orbital precession, remnant recoil, hierarchical formation, and cosmological mirror symmetry.
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All authors Juan Calderón Bustillo, Adrián del Rio, Nicolás Sanchis-Gual, Koustav Chandra

Quantum Physics

Cavity method for permutation models on Cayley trees

Masayuki Ohzeki

Motivated by permutation statistical models arising in random tensor networks, we study permutation models on a Cayley tree whose variables take values in the symmetric group $\Sn$. The pair interaction is assumed to depend only on the cycle type of the relative permutation. Then the Boltzmann weight is written as a class function on $\Sn$. This property diagonalizes the edge convolution operator in irreducible representation sectors. As a result, the linear stability of the uniform paramagnetic cavity solution is controlled by the character eigenvalue ratios. For cycle-factorized weights, these eigenvalues can be expressed as specializations of Schur functions. We derive the instability criteria and also verify their validity by comparison with direct numerical iterations of the cavity equation.
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Superconductivity

AC calorimetric study of magneto-quantum oscillations in anisotropic multiband V$_2$Ga$_5$ superconductor

Yevhen V. Petrenko, Jozef Kačmarčík, Tomáš Samuely et al. (+7 more)

Unlike de Haas–van Alphen measurements, heat-capacity magneto-quantum oscillations directly probe the oscillatory bulk quasiparticle density of states. Here, we report the observation of MQOs in V$_2$Ga$_5$ single crystals studied via highly sensitive ac calorimetry. The strongest MQO signal is observed for a magnetic field applied along the vanadium chains, in excellent agreement with de Haas–van Alphen magnetization data. A single dominant frequency of 126.6 T resolved by fast Fourier transform confirms the true bulk origin of the elliptical $\gamma$ Fermi-surface pocket located near the Z point of the Brillouin zone. The angular dependence of the FFT frequency closely tracks the anisotropy of the $\gamma$ pocket, as supported by first-principles calculations. Analysis of the temperature- and field-dependent MQO amplitudes allows the precise determination of the effective cyclotron mass, Dingle temperature, quantum relaxation time, carrier mobility, and electron mean free path. Furthermore, we demonstrate that the net Berry flux is invariant with respect to the magnetic-field orientation, as a consequence of a conserved hybridization phase twist within the $\gamma$ pocket. These findings establish ac calorimetry as a powerful macroscopic probe of topological orbital hybridization in complex intermetallics.
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All authors Yevhen V. Petrenko, Jozef Kačmarčík, Tomáš Samuely, Jozef Haniš, Slavomír Gabáni, Szymon Królak, Michal J. Winiarski, Tomasz Klimczuk, Martin Gmitra, Peter Samuely

Cosmology and Nongalactic Astrophysics

Alleviating the Hubble tension with the $\Lambda_{\omega_s}$CDM model

Youri Carloni

We formulate a novel extension of the $\Lambda$CDM model, named $\Lambda_{\omega_s}$CDM, in which we consider an additional term at early times in order to alleviate the Hubble tension. This additional component, referred to as matter with pressure, indicates a barotropic fluid that is subdominant to dust and radiation as the Universe expands, thereby recovering the $\Lambda$CDM paradigm at late times. We constrain the $\Lambda_{\omega_s}$CDM cosmology by performing a Markov Chain Monte Carlo analysis with Planck 2018 CMB, DESI DR2, and Pantheon+SH0ES data. The results suggest that the barotropic factor and the normalized density of the new fluid are given, respectively, by $\omega_s=0.294_{-0.004(0.023)}^{+0.014(0.015)}$ and $10^{5}\Omega_s=1.62_{-0.56(0.91)}^{+0.36(1.02)}$. With these two additional parameters, the Hubble constant is increased to $H_0 = 71.51^{+0.72(1.43)}_{-0.74(1.46)}$ km/s/Mpc, alleviating de facto the Hubble tension.
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Earth and Planetary Astrophysics

Shape, Orientation and Colors Combined approach for Asteroids (SOCCA)

K. O. Xenos, B. Carry, J. Peloton et al. (+3 more)

Large photometric surveys provide sparse multi-band photometry for millions of Solar System objects, offering an opportunity to jointly constrain their physical and compositional properties. However, current phase function models do not account for rotational variability, limiting their ability to retrieve accurate parameters. Similarly, methods that recover shape and rotational parameters remain both computationally and observationally expensive. We present a model capable of simultaneously retrieving the absolute magnitude, phase parameters, spin state, and shape proportions of SSOs from sparse photometric data, while remaining computationally efficient. We introduce the Shape, Orientation and Colors Combined approach for Asteroids (SOCCA), which extends the HG1G2 formalism by incorporating the projected surface of a rotating triaxial ellipsoid. The model jointly fits multi-band photometry, and includes a dedicated treatment of rotational period determination. We implement the model on a 10-year LSST simulation as well as on real data of asteroid (45) Eugenia for validation purposes. SOCCA significantly improves the fit to photometric data, reducing the mean residuals to half, compared to previous models. It retrieves the absolute magnitude with a scatter about three times smaller than existing approaches, and improves the determination of phase parameters by a similar factor. It also recovers the sidereal rotation period, spin axis orientation and the axes ratios of the best fitting ellipsoid. The inclusion of shape and rotation increases the number of physically meaningful solutions by 10-20% per filter, leading to an overall success rate of 53%. Its performance and scalability make it well suited for current and upcoming large surveys such as the Zwicky Transient Facility and the recently started Legacy Survey of Space and Time.
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All authors K. O. Xenos, B. Carry, J. Peloton, M. Mahlke, J. Berthier, P.-A. Mattei

Computational Physics

Latent Residual-Closure Fourier Neural Operator for Robust Multi-Field Solving in Particle-in-Cell Simulations

Jianhua Lyu and Linlin Zhong

Particle-in-cell (PIC) simulations are widely used for kinetic plasma modeling in energy applications, but their efficiency is often limited by repeated field solves on dense meshes. This work proposes a Latent Residual-Closure Fourier Neural Operator (LRC-FNO) for robust surrogate multi-field solving in PIC simulations. Rather than treating field prediction as a purely data-driven regression task, LRC-FNO formulates PIC field solving as a two-level residual-closure problem involving source compression and source-to-field operator mapping. An autoencoder extracts compact representations of particle-deposited source fields, while a Latent Closure Refiner recovers unresolved residual structures lost during compression. A Coarse-FNO Solver captures the dominant field response, and a Residual-Closure FNO restores full-resolution corrections. The method is tested on three benchmarks with increasing complexity: 1D linear Landau damping (LLD), 2D two-stream instability (TSI), and a 2D scrape-off layer (SOL) fusion plasma model. In LLD and TSI, LRC-FNO better preserves charge-to-potential mapping, potential-mode evolution, residual charge structures, and particle-field energy exchange during closed-loop PIC integration. In the SOL case, LRC-FNO achieves relative L2 errors of 0.0447 for the self-consistent potential and 0.0251 for the magnetic vector potential in single-step prediction. More importantly, when used as a neural initial guess with 20 iterative corrections, LRC-FNO maintains strong physical consistency in extrapolated closed-loop simulations, preserving charge and current density structures over a time range close to twice the training horizon. These results demonstrate that LRC-FNO can serve as both a fast surrogate field solver and a high-quality initialization strategy for iterative PIC field solvers.
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Quantum Physics

Dimension-Free Approximate Tensorization of Quantum Hypercontractivity for Qudit Depolarizing Semigroups

Yangjing Dong, Li Gao, Fengning Ou et al. (+2 more)

We prove approximate tensorization for hypercontractivity and logarithmic-Sobolev constants for a class of primitive reversible quantum Markov semigroups satisfying the positive off-diagonal scaling (PODS) condition. This class includes qubit examples and generalized depolarizing semigroups with respect to full-rank states in arbitrary finite dimensions. For any such semigroup $(\Phi_t)_{t\ge 0}$ and every tensor power $n$, we show that the log-Sobolev constant of the product semigroup $\Phi_t^{\otimes n}$ is at least $2/(3\ln 2)\approx 0.96$ times the log-Sobolev constant of the single-site semigroup $\Phi_t$, independently of $n$ and the local dimension $d$. The proof first establishes an exact tensorization of the $(q,2)$-hypercontractive inequality for integer $q$, in particular $q=3$, and then extends the estimate to all real $q>2$ by complex interpolation; the standard implication from hypercontractivity to logarithmic-Sobolev inequalities yields the stated almost tensorization result. In the qubit case, we further prove exact tensorization for primitive reversible PODS semigroups and obtain sharp $(q,2)$-hypercontractivity estimates for generalized qubit depolarizing channels.
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All authors Yangjing Dong, Li Gao, Fengning Ou, Penghui Yao, Haigang Zhou

Nuclear Theory

Mass Probe of Tetrahedral Symmetry in Atomic Nuclei

F. F. Xu and P. W. Zhao

Tetrahedral symmetry has long been predicted as an exotic shape degree of freedom in atomic nuclei, yet clear experimental manifestations remain elusive. We show that the triple binding energy difference $\delta V_{pn}^{(3)}$ can isolate a structural effect of tetrahedral symmetry in $^{80}$Zr. Using relativistic density functional theory solved on a three-dimensional lattice without symmetry restrictions, the experimental $\delta V_{pn}^{(3)}$ values for even-even $^{80\text{-}90}$Zr isotopes are well reproduced without adjustable parameters. While an enhancement of $\delta V_{pn}^{(3)}$ near $N\simeq Z$ is commonly attributed to proton-neutron correlations beyond the mean field, the pronounced nonmonotonic peak at $N=40$ emerges at the mean-field level only when the tetrahedral degree of freedom is included. Constraining the tetrahedral deformation to zero removes the peak and leads to clear deviations from experiment. The anomaly is traced to a well-localized tetrahedral minimum in $^{80}$Zr, supported by potential energy surfaces and characteristic single-particle level splittings. Calculations restricted to quadrupole and triaxial shapes fail to reproduce the localized enhancement, indicating that the effect is not a generic proton-neutron correlation but a symmetry-selective increase of proton-neutron binding associated with tetrahedral geometry. We therefore identify the $\delta V_{pn}^{(3)}$ anomaly in $^{80}$Zr as a structural mechanism distinct from the conventional Wigner-type enhancement and show that nuclear masses constitute a sensitive probe of tetrahedral symmetry.
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High Energy Physics (Experiment)

Observation of an Altered $a_{0}(980)$ Line shape in $D^{+} \rightarrow \pi^{+}\eta\eta$

BESIII Collaboration: M. Ablikim, M. N. Achasov, P. Adlarson et al. (+718 more)

Using $20.3~{\rm fb}^{-1}$ of $e^+e^-$ collision data collected with the BESIII detector at $\sqrt{s}=3.773~{\rm GeV}$, we perform the first amplitude analysis of the decay $D^+\to\pi^+\eta\eta$. The intermediate process $D^+\to a_0(980)^+\eta$, $a_0(980)^+\to\pi^+\eta$, is observed as the only significant component in the amplitude analysis, and its branching fraction is measured to be $(3.67\pm0.12_{\rm stat}\pm0.06_{\rm syst})\times10^{-3}$. The $\pi^+\eta$ mass spectrum associated with $a_0(980)^+\eta$ production exhibits a line shape that differs substantially from those observed in $D_{(s)}\to a_0(980)\pi$ and $D^0\to a_0(980)^-e^+\nu_e$ decays. We examine several conventional descriptions of the $a_0(980)$ amplitude, including Flatté, dispersively modified Flatté, $T$-matrix, and $K$-matrix parameterizations. With reference $a_0(980)$ parameters, neither these models nor their extensions including additional small resonant or non-resonant amplitudes reproduce the observed line shape satisfactorily. When the $a_0(980)$ parameters are allowed to float, satisfactory fits can be obtained, but the pole mass is driven well above the $K\bar K$ threshold, inconsistent with the near-threshold character of the $a_0(980)$. The results reveal a tension between fit quality and the physical pole position in conventional direct-production amplitude models.
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All authors BESIII Collaboration: M. Ablikim, M. N. Achasov, P. Adlarson, X. C. Ai, R. Aliberti, A. Amoroso, Q. An, Y. Bai, O. Bakina, Y. Ban, H.-R. Bao, V. Batozskaya, K. Begzsuren, N. Berger, M. Berlowski, M. Bertani, D. Bettoni, F. Bianchi, E. Bianco, A. Bortone, I. Boyko, R. A. Briere, A. Brueggemann, H. Cai, M. H. Cai, X. Cai, A. Calcaterra, G. F. Cao, N. Cao, S. A. Cetin, X. Y. Chai, J. F. Chang, G. R. Che, Y. Z. Che, C. H. Chen, Chao Chen, G. Chen, H. S. Chen, H. Y. Chen, M. L. Chen, S. J. Chen, S. L. Chen, S. M. Chen, T. Chen, X. R. Chen, X. T. Chen, X. Y. Chen, Y. B. Chen, Y. Q. Chen, Y. Q. Chen, Z. J. Chen, Z. K. Chen, S. K. Choi, X. Chu, G. Cibinetto, F. Cossio, J. Cottee-Meldrum, J. J. Cui, H. L. Dai, J. P. Dai, A. Dbeyssi, R. E. de Boer, D. Dedovich, C. Q. Deng, Z. Y. Deng, A. Denig, I. Denysenko, M. Destefanis, F. De Mori, B. Ding, X. X. Ding, Y. Ding, Y. Ding, Y. X. Ding, J. Dong, L. Y. Dong, M. Y. Dong, X. Dong, M. C. Du, S. X. Du, S. X. Du, Y. Y. Duan, P. Egorov, G. F. Fan, J. J. Fan, Y. H. Fan, J. Fang, J. Fang, S. S. Fang, W. X. Fang, Y. Q. Fang, R. Farinelli, L. Fava, F. Feldbauer, G. Felici, C. Q. Feng, J. H. Feng, L. Feng, Q. X. Feng, Y. T. Feng, M. Fritsch, C. D. Fu, J. L. Fu, Y. W. Fu, H. Gao, X. B. Gao, Y. Gao, Y. N. Gao, Y. N. Gao, Y. Y. Gao, S. Garbolino, I. Garzia, P. T. Ge, Z. W. Ge, C. Geng, E. M. Gersabeck, A. Gilman, K. Goetzen, J. D. Gong, L. Gong, W. X. Gong, W. Gradl, S. Gramigna, M. Greco, M. H. Gu, Y. T. Gu, C. Y. Guan, A. Q. Guo, L. B. Guo, M. J. Guo, R. P. Guo, Y. P. Guo, A. Guskov, J. Gutierrez, K. L. Han, T. T. Han, F. Hanisch, K. D. Hao, X. Q. Hao, F. A. Harris, K. K. He, K. L. He, F. H. Heinsius, C. H. Heinz, Y. K. Heng, C. Herold, P. C. Hong, G. Y. Hou, X. T. Hou, Y. R. Hou, Z. L. Hou, H. M. Hu, J. F. Hu, Q. P. Hu, S. L. Hu, T. Hu, Y. Hu, Z. M. Hu, G. S. Huang, K. X. Huang, L. Q. Huang, P. Huang, X. T. Huang, Y. P. Huang, Y. S. Huang, T. Hussain, N. Hüsken, N. in der Wiesche, J. Jackson, Q. Ji, Q. P. Ji, W. Ji, X. B. Ji, X. L. Ji, Y. Y. Ji, Z. K. Jia, D. Jiang, H. B. Jiang, P. C. Jiang, S. J. Jiang, T. J. Jiang, X. S. Jiang, Y. Jiang, J. B. Jiao, J. K. Jiao, Z. Jiao, S. Jin, Y. Jin, M. Q. Jing, X. M. Jing, T. Johansson, S. Kabana, N. Kalantar-Nayestanaki, X. L. Kang, X. S. Kang, M. Kavatsyuk, B. C. Ke, V. Khachatryan, A. Khoukaz, R. Kiuchi, O. B. Kolcu, B. Kopf, M. Kuessner, X. Kui, N. Kumar, A. Kupsc, W. Kühn, Q. Lan, W. N. Lan, T. T. Lei, M. Lellmann, T. Lenz, C. Li, C. Li, C. Li, C. H. Li, C. K. Li, D. M. Li, F. Li, G. Li, H. B. Li, H. J. Li, H. N. Li, Hui Li, J. R. Li, J. S. Li, K. Li, K. L. Li, K. L. Li, L. J. Li, Lei Li, M. H. Li, M. R. Li, P. L. Li, P. R. Li, Q. M. Li, Q. X. Li, R. Li, S. X. Li, T. Li, T. Y. Li, W. D. Li, W. G. Li, X. Li, X. H. Li, X. L. Li, X. Y. Li, X. Z. Li, Y. Li, Y. G. Li, Y. P. Li, Z. J. Li, Z. Y. Li, H. Liang, Y. F. Liang, Y. T. Liang, G. R. Liao, L. B. Liao, M. H. Liao, Y. P. Liao, J. Libby, A. Limphirat, C. C. Lin, D. X. Lin, L. Q. Lin, T. Lin, B. J. Liu, B. X. Liu, C. Liu, C. X. Liu, F. Liu, F. H. Liu, Feng Liu, G. M. Liu, H. Liu, H. B. Liu, H. H. Liu, H. M. Liu, Huihui Liu, J. B. Liu, J. J. Liu, K. Liu, K. Liu, K. Y. Liu, Ke Liu, L. Liu, L. C. Liu, Lu Liu, M. H. Liu, P. L. Liu, Q. Liu, S. B. Liu, T. Liu, W. K. Liu, W. M. Liu, W. T. Liu, X. Liu, X. Liu, X. K. Liu, X. Y. Liu, Y. Liu, Y. Liu, Yuan Liu, Y. B. Liu, Z. A. Liu, Z. D. Liu, Z. Q. Liu, X. C. Lou, F. X. Lu, H. J. Lu, J. G. Lu, X. L. Lu, Y. Lu, Y. H. Lu, Y. P. Lu, Z. H. Lu, C. L. Luo, J. R. Luo, J. S. Luo, M. X. Luo, T. Luo, X. L. Luo, Z. Y. Lv, X. R. Lyu, Y. F. Lyu, Y. H. Lyu, F. C. Ma, H. L. Ma, J. L. Ma, L. L. Ma, L. R. Ma, Q. M. Ma, R. Q. Ma, R. Y. Ma, T. Ma, X. T. Ma, X. Y. Ma, Y. M. Ma, F. E. Maas, I. MacKay, M. Maggiora, S. Malde, Q. A. Malik, H. X. Mao, Y. J. Mao, Z. P. Mao, S. Marcello, A. Marshall, F. M. Melendi, Y. H. Meng, Z. X. Meng, G. Mezzadri, H. Miao, T. J. Min, R. E. Mitchell, X. H. Mo, B. Moses, N. Yu. Muchnoi, J. Muskalla, Y. Nefedov, F. Nerling, L. S. Nie, I. B. Nikolaev, Z. Ning, S. Nisar, Q. L. Niu, W. D. Niu, C. Normand, S. L. Olsen, Q. Ouyang, S. Pacetti, X. Pan, Y. Pan, A. Pathak, Y. P. Pei, M. Pelizaeus, H. P. Peng, X. J. Peng, Y. Y. Peng, K. Peters, K. Petridis, J. L. Ping, R. G. Ping, S. Plura, V. Prasad, F. Z. Qi, H. R. Qi, M. Qi, S. Qian, W. B. Qian, C. F. Qiao, J. H. Qiao, J. J. Qin, J. L. Qin, L. Q. Qin, L. Y. Qin, P. B. Qin, X. P. Qin, X. S. Qin, Z. H. Qin, J. F. Qiu, Z. H. Qu, J. Rademacker, C. F. Redmer, A. Rivetti, M. Rolo, G. Rong, S. S. Rong, F. Rosini, Ch. Rosner, M. Q. Ruan, N. Salone, A. Sarantsev, Y. Schelhaas, K. Schoenning, M. Scodeggio, K. Y. Shan, W. Shan, X. Y. Shan, Z. J. Shang, J. F. Shangguan, L. G. Shao, M. Shao, C. P. Shen, H. F. Shen, W. H. Shen, X. Y. Shen, B. A. Shi, H. Shi, J. L. Shi, J. Y. Shi, S. Y. Shi, X. Shi, H. L. Song, J. J. Song, T. Z. Song, W. M. Song, Y. J. Song, Y. X. Song, S. Sosio, S. Spataro, F. Stieler, S. S Su, Y. J. Su, G. B. Sun, G. X. Sun, H. Sun, H. K. Sun, J. F. Sun, K. Sun, L. Sun, S. S. Sun, T. Sun, Y. C. Sun, Y. H. Sun, Y. J. Sun, Y. Z. Sun, Z. Q. Sun, Z. T. Sun, C. J. Tang, G. Y. Tang, J. Tang, J. J. Tang, L. F. Tang, Y. A. Tang, L. Y. Tao, M. Tat, J. X. Teng, J. Y. Tian, W. H. Tian, Y. Tian, Z. F. Tian, I. Uman, B. Wang, B. Wang, Bo Wang, C. Wang, C. Wang, Cong Wang, D. Y. Wang, H. J. Wang, J. J. Wang, K. Wang, L. L. Wang, L. W. Wang, M. Wang, M. Wang, N. Y. Wang, S. Wang, T. Wang, T. J. Wang, W. Wang, Wei Wang, W. P. Wang, X. Wang, X. F. Wang, X. J. Wang, X. L. Wang, X. N. Wang, Y. Wang, Y. D. Wang, Y. F. Wang, Y. H. Wang, Y. J. Wang, Y. L. Wang, Y. N. Wang, Y. Q. Wang, Yaqian Wang, Yi Wang, Yuan Wang, Z. Wang, Z. L. Wang, Z. L. Wang, Z. Q. Wang, Z. Y. Wang, D. H. Wei, H. R. Wei, F. Weidner, S. P. Wen, Y. R. Wen, U. Wiedner, G. Wilkinson, M. Wolke, C. Wu, J. F. Wu, L. H. Wu, L. J. Wu, L. J. Wu, Lianjie Wu, S. G. Wu, S. M. Wu, X. Wu, X. H. Wu, Y. J. Wu, Z. Wu, L. Xia, X. M. Xian, B. H. Xiang, D. Xiao, G. Y. Xiao, H. Xiao, Y. L. Xiao, Z. J. Xiao, C. Xie, K. J. Xie, X. H. Xie, Y. Xie, Y. G. Xie, Y. H. Xie, Z. P. Xie, T. Y. Xing, C. F. Xu, C. J. Xu, G. F. Xu, H. Y. Xu, H. Y. Xu, M. Xu, Q. J. Xu, Q. N. Xu, T. D. Xu, W. Xu, W. L. Xu, X. P. Xu, Y. Xu, Y. Xu, Y. C. Xu, Z. S. Xu, F. Yan, H. Y. Yan, L. Yan, W. B. Yan, W. C. Yan, W. H. Yan, W. P. Yan, X. Q. Yan, H. J. Yang, H. L. Yang, H. X. Yang, J. H. Yang, R. J. Yang, T. Yang, Y. Yang, Y. F. Yang, Y. H. Yang, Y. Q. Yang, Y. X. Yang, Y. Z. Yang, M. Ye, M. H. Ye, Z. J. Ye, Junhao Yin, Z. Y. You, B. X. Yu, C. X. Yu, G. Yu, J. S. Yu, L. Q. Yu, M. C. Yu, T. Yu, X. D. Yu, Y. C. Yu, C. Z. Yuan, H. Yuan, J. Yuan, J. Yuan, L. Yuan, S. C. Yuan, X. Q. Yuan, Y. Yuan, Z. Y. Yuan, C. X. Yue, Ying Yue, A. A. Zafar, S. H. Zeng, X. Zeng, Y. Zeng, Yujie Zeng, Y. J. Zeng, X. Y. Zhai, Y. H. Zhan, A. Q. Zhang, B. L. Zhang, B. X. Zhang, D. H. Zhang, G. Y. Zhang, G. Y. Zhang, H. Zhang, H. Zhang, H. C. Zhang, H. H. Zhang, H. Q. Zhang, H. R. Zhang, H. Y. Zhang, Jin Zhang, J. Zhang, J. J. Zhang, J. L. Zhang, J. Q. Zhang, J. S. Zhang, J. W. Zhang, J. X. Zhang, J. Y. Zhang, J. Z. Zhang, Jianyu Zhang, L. M. Zhang, Lei Zhang, N. Zhang, P. Zhang, Q. Zhang, Q. Y. Zhang, R. Y. Zhang, S. H. Zhang, Shulei Zhang, X. M. Zhang, X. Y Zhang, X. Y. Zhang, Y. Zhang, Y. Zhang, Y. T. Zhang, Y. H. Zhang, Y. M. Zhang, Y. P. Zhang, Z. D. Zhang, Z. H. Zhang, Z. L. Zhang, Z. L. Zhang, Z. X. Zhang, Z. Y. Zhang, Z. Y. Zhang, Z. Z. Zhang, Zh. Zh. Zhang, G. Zhao, J. Y. Zhao, J. Z. Zhao, L. Zhao, L. Zhao, M. G. Zhao, N. Zhao, R. P. Zhao, S. J. Zhao, Y. B. Zhao, Y. L. Zhao, Y. X. Zhao, Z. G. Zhao, A. Zhemchugov, B. Zheng, B. M. Zheng, J. P. Zheng, W. J. Zheng, X. R. Zheng, Y. H. Zheng, B. Zhong, C. Zhong, H. Zhou, J. Q. Zhou, J. Y. Zhou, S. Zhou, X. Zhou, X. K. Zhou, X. R. Zhou, X. Y. Zhou, Y. X. Zhou, Y. Z. Zhou, A. N. Zhu, J. Zhu, K. Zhu, K. J. Zhu, K. S. Zhu, L. Zhu, L. X. Zhu, S. H. Zhu, T. J. Zhu, W. D. Zhu, W. D. Zhu, W. J. Zhu, W. Z. Zhu, Y. C. Zhu, Z. A. Zhu, X. Y. Zhuang, J. H. Zou, J. Zu

High Energy Physics (Theory)

Aspects of Witten Diagrams for Holographic Defects

Dean Carmi, Sudip Ghosh and Trakshu Sharma

In this paper, we study the conformal block decomposition of Witten diagrams for $d$-dimensional holographic CFTs in the presence of a $p$-dimensional conformal defect. The holographic dual in this case contains a probe AdS$_{p+1}$ brane embedded inside AdS$_{d+1}$. In particular, we focus on contact, tree-level exchanges and some one-loop two-point Witten diagrams, which contribute to the two-point function of CFT bulk scalar operators. We also consider a tree-level exchange diagram for a three-point function involving one CFT bulk scalar operator and two scalar operators localized on the defect. Employing the split representation of AdS propagators, adapted to the probe brane setup, we perform the direct channel conformal block decompositions of these diagrams. In the case of tree-level diagrams, we obtain explicit expressions for the OPE coefficients in the direct channel decompositions. For two-point tree-level exchange diagrams, we derive recursion relations for the coefficients in the crossed-channel block expansions and compute the seed coefficients which serve as inputs for these relations. Our explicit results for the block decomposition coefficients for tree-level Witten diagrams are potentially useful for further developing the analytic functional approach to bootstrapping two-point functions of bulk operators in general defect CFTs. We also study the crossing kernel, which encodes the bulk channel partial wave expansion of a defect channel partial wave. Using the bulk channel Lorentzian inversion formula for defect CFTs, we derive closed form expressions for this defect-to-bulk channel crossing kernel for zero-dimensional defects in $d=2,4$ dimensions and surface defects in $d=4,6$ dimensions.
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Quantum Physics

Optimizing bias-tailored quantum error correction beyond code-capacity noise

César Benito, I. Jesán Velázquez-Reséndiz and Alejandro Bermudez

We find that the substantial advantages predicted for bias-tailored quantum error correction (QEC) under code-capacity noise are strongly reduced once realistic syndrome extraction and circuit-level noise models are considered. We start by comparing XZZX codes to rectangular surface codes with a bias-dependent optimised anisotropy. Although code-capacity simulations predict an advantage of rectangular surface codes in the limit of high noise bias, this actually disappears under circuit-level noise, making the XZZX codes the preferred and simplest choice even for platforms that allow for a flexible variation of the code layout adapted to changes in noise calibration. Our results identify bias degradation during syndrome extraction under circuit-level noise as the central limitation of biased-tailored QEC. To partially mitigate this effect, we introduce a bias-filtering CNOT gadget that temporarily encodes the ancillary target qubit during syndrome extraction in a repetition code and, upon measurement and feed forward, manages to reduce the bias degradation. In a regime of high-bias and low-idle errors, this bias-filtering gadget yields a few-percent relative improvement of the XZZX code error threshold, demonstrating that lightweight bias-filtering strategies can recover part of the lost bias-tailoring advantage for realistic circuit-level noise.
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High Energy Physics (Theory)

Monopoles, Center Vortices, Confinement in (3+1)d, and the Lens-Space Twisted Partition Function

Yui Hayashi and Yuya Tanizaki

We propose the gauge-invariant criteria of center-vortex condensation and monopole condensation using the $\mathbb{Z}_N^{[1]}$-symmetry twisted partition functions: The torus twisted partition function characterizes the center-vortex condensation, and the lens-space twisted partition function characterizes the monopole condensation. To justify our proposal, we study how these twisted partition functions behave in the adjoint Higgs phase and show that their leading nontrivial contributions come from the center vortex and monopole, respectively. Using the techniques of topological field theories, we uncover the relation between the center-vortex and monopole condensations, and in particular, we prove that the gapped phase with the center-vortex condensation necessarily shows the monopole condensation, too. We then study a center-vortex model with monopoles as an illustrative example, and the higher-charge monopole condensation gives an example of the symmetry fractionalization, which goes beyond the conventional Wilson-'t Hooft classification.
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Superconductivity

AC-flux-driven SQUID diode spectroscopy as a probe of current-phase relations

Yuriy Yerin, Iman Askerzade, Alexey Fedorchenko et al. (+2 more)

The current-phase relation (CPR) of a Josephson junction encodes microscopic information on superconducting states through higher-order and fractional harmonics. However, their unambiguous extraction is challenging, as different CPR components produce nearly identical static interference patterns that are further obscured by device asymmetries, damping, and dynamical effects. Here, we propose probing individual CPR harmonics via the ac magnetic-flux-driven diode effect in asymmetric dc SQUIDs with unequal junction critical currents. Using two complementary reductions of the fast-driven dynamics – a Kapitza-type perturbation theory for the conventional junction and a Jacobi–Anger averaging for a general CPR – we show that ac flux modulation dresses each harmonic with a distinct Bessel function, yielding characteristic signatures in the diode efficiency $\eta(\phi_{\rm ac},\omega)$ as a function of ac flux amplitude $\phi_{\rm ac}$ and frequency $\omega$. We verify and extend these predictions by numerical solutions of the coupled dynamical equations for CPRs containing $\sin\varphi$, $\sin(\varphi/2)$, and $\sin 2\varphi$ terms ($\varphi$: superconducting phase difference), and construct phase diagrams of $\eta(\phi_{\rm ac},\omega)$. Distinct CPR components are revealed to produce characteristic weak, sparse, dense, or intermodulated arc patterns that remain robust in both overdamped and underdamped regimes. This suggests ac-flux-driven SQUID diode spectroscopy as a probe of current-phase relations in topological materials, multiband systems, and other unconventional superconductors.
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All authors Yuriy Yerin, Iman Askerzade, Alexey Fedorchenko, Ali Gencer, Oleksandr Dobrovolskiy

Soft Condensed Matter

Using fast-reactive crosslinkers to modulate the internal structure of thermoresponsive microgels

Ballin Elisa, Brasili Francesco, Sztucki Michael et al. (+3 more)

The internal architecture of poly(N-isopropylacrylamide) (PNIPAM) microgels, which switches from fuzzy-sphere to star-like when the standard N,N'-methylenebis(acrylamide) (BIS) crosslinker is replaced with ethylene glycol dimethacrylate (EGDMA), critically determines their interactions and swelling behavior. Here, we systematically investigate the role of the surfactant and crosslinker content in modulating the internal structure of the microgels using Dynamic Light Scattering, Small-angle X-ray Scattering and monomer-resolved numerical simulations. We reveal that the presence of the surfactant is crucial for obtaining the star-like architecture, and that the transition from the star-like regime to a more core-dominated structure occurs above a threshold EGDMA concentration. Monomer-resolved simulations capture how the role of surfactant differs between EGDMA-crosslinked and BIS-crosslinked microgels. Our findings establish a direct synthesis-structure relationship, providing a clear guidance for the rational design of soft, star-like microgels with ultra-soft interactions, strenghtening the connection between microgels and model star polymers.
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All authors Ballin Elisa, Brasili Francesco, Sztucki Michael, Rovigatti Lorenzo, Sennato Simona, Zaccarelli Emanuela

Cosmology and Nongalactic Astrophysics

A rare sextuple-merging brightest cluster galaxy system in a disturbed galaxy cluster observed with the Einstein Probe Follow-up X-ray Telescope

Z. L. Wen, S. M. Jia, Z. S. Yuan et al. (+12 more)

The evolutionary processes of galaxy clusters influence the properties of their member galaxies. We present a joint X-ray–optical analysis of the galaxy cluster WHY J050106.2+013714 at $z_{\rm c}=0.151$. X-ray observations with the Einstein Probe Follow-up X-ray Telescope indicate that the cluster is dynamically young. The cluster displays an average X-ray temperature of $2.8^{+0.4}_{-0.3}$ keV and a total luminosity of 9.4$\pm0.3\times10^{43}$ erg s$^{-1}$, consistent with the scaling relation of typical disturbed clusters. Remarkably, the cluster hosts a multi-merging brightest cluster galaxy (BCG) system composed of six massive galaxies, with a total stellar mass of $1.16\times10^{12}M_{\odot}$. We detected a well-defined intracluster light component extending to a size of 310 kpc. A systematic search for merging BCGs in the DESI Legacy Surveys reveals that this sextuple-merging BCG is extremely rare in the local Universe. Additionally, other merging BCGs are also likely to form in moderately disturbed clusters, which provides valuable insights into the formation of BCGs.
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All authors Z. L. Wen, S. M. Jia, Z. S. Yuan, M. T. Shen, Y. Chen, C. K. Li, C. Ge, L. M. Song, H. Feng, J. Guan, C. C. Jin, C. Z. Liu, Y. Liu, S. N. Zhang, H. S. Zhao

Optics

Multipolar optical binding in focus

Ashutosh Shukla, Sneha Boby and G V Pavan Kumar

The optical binding of gold nanoparticles has conventionally been explored within the Rayleigh limit using dipole approximations. But the field is increasingly focusing on the Mie regime for particles in the 100-500 nm range, where the dipole approximation is insufficient, and a complex landscape of multipolar resonances must be considered. This can be leveraged to engineer more complex forms of optical matter. To this end, we computationally study the optical binding force landscapes experienced by a pair of AuNPs using generalized multiparticle Mie theory. We calculate the total optical binding forces and mechanical trap stiffness values ($dF_i/di$) at the specific resonance wavelengths where the electric dipole, quadrupole, or octupole modes reach their respective scattering peaks and dominate the mechanical response. We demonstrate that the plasmonic mode symmetry greatly influences the spatial distribution of zero-force nodes and the rigidity of the optically bound dimer. By aligning these multipolar phenomena with standard experimental configurations, this work provides a mechanical framework for programmable metafluids and reconfigurable micromachines, bridging the gap between fundamental electrodynamics and reconfigurable nanomanipulation.
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Statistical Mechanics

First-order phase transitions in the three-dimensional Blume-Capel ferromagnet

D. Mataragkas, A. Vasilopoulos, Z.D. Vatansever et al. (+3 more)

We investigate first-order phase transitions in the three-dimensional Blume-Capel ferromagnet on the simple cubic lattice by combining multicanonical simulations with two-parameter Wang-Landau sampling. The generalized-ensemble approach enables a detailed characterization of the coexistence region over a broad range of temperatures and crystal-field couplings, extending from the vicinity of the tricritical point deep into the first-order regime. We analyze the finite-size scaling behavior of thermodynamic observables, with particular emphasis on the energy probability density function, free-energy barriers, and interfacial properties. The evolution of the double-peaked energy distributions reveals a gradual crossover from weak to strong first-order behavior as the temperature is lowered. From the scaling of the free-energy barrier we determine the interface tension along the coexistence line and characterize its approach to the tricritical region through its vanishing behavior. In parallel, a field-mixing analysis based on the joint density of states obtained from two-parameter Wang-Landau simulations is employed to locate first-order transition points and probe tricritical behavior. While this approach has been highly successful in two-dimensional realizations of the Blume-Capel model, we find that in three dimensions its practical implementation becomes increasingly sensitive in the vicinity of the tricritical region, where the shallow structure of the relevant scaling variable distribution limits the ability to resolve coexistence conditions for the system sizes currently accessible. These results delineate the range of applicability of the method in three dimensions and provide a consistent picture of the first-order regime of the model.
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All authors D. Mataragkas, A. Vasilopoulos, Z.D. Vatansever, Y. Kim, D.-H. Kim, N.G Fytas

High Energy Astrophysical Phenomena

A catalogue of TeV pulsar environments

Tina Wach, Tim Linden, Alison M.W. Mitchell et al. (+1 more)

Pulsars and their environments represent a major class of Galactic gamma-ray sources. Their complex evolution, shaped by the interactions of the pulsar outflow with the supernova remnant (SNR) and the surrounding interstellar medium (ISM), produces diverse morphological and spectral characteristics observable from radio to PeV energies. This work collects and homogenizes data from all major operating TeV observatories, presenting the first comprehensive catalogue of TeV gamma-ray properties of pulsar environments. The catalogue is created from information regarding all gamma-ray sources that have been classified as pulsar-associated sources in published results from H.E.S.S., MAGIC, VERITAS, HAWC, and LHAASO. For each source, the observed gamma-ray properties are cross-matched with pulsar properties from the ATNF catalogue and Fermi-LAT pulsar catalogue. The final catalogue comprises all currently known TeV sources associated with pulsars, spanning all evolutionary stages. The sample consists of 128 gamma-ray sources, connected to 66 different pulsars. It reflects that the TeV-detected population is dominated by young and energetic pulsars located near the Galactic plane, but includes a growing number of middle-aged systems detected as extended halos. Only a weak correlation is found between TeV luminosity and pulsar characteristic age, indicating that TeV evolution is driven by environmental and transport effects rather than by spin-down age alone. Additionally, 5 pulsars which should host a PWN detectable by CTAO are identified as prime targets for future observation to improve our understanding of properties inhibiting the formation of a TeV nebula. This publicly available catalogue provides a uniform foundation for future population studies and for constraining models of particle transport and energy losses in pulsar environments.
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All authors Tina Wach, Tim Linden, Alison M.W. Mitchell, Samuel T. Spencer

Mathematical Physics

Semiclassical Analysis of Tunneling in Graphene under Nonuniform Electrostatic and Magnetic Fields

Maria V. Perel

We develop a semiclassical theory of tunnelling of Dirac fermions through an n-p-n junction in monolayer graphene subjected to a perpendicular magnetic field. Electrostatic and magnetic fields are assumed to be smooth functions of a single spatial coordinate, supported on a finite interval, vanishing outside it, and thus ensuring asymptotically free states. In contrast to earlier studies restricted to constant magnetic fields and exactly solvable electrostatic potential profiles, we consider a general electrostatic potential forming an n-p-n junction and an arbitrary magnetic field, and formulate the corresponding scattering problem. Within the semiclassical approximation, and under an additional assumption on the incidence angle, the problem reduces to a connection problem for a pair of degeneracy points, treated using results from our earlier work. We obtain explicit expressions for the reflection and transmission coefficients, including their phases, as functions of energy and incidence angle. Furthermore, we derive semiclassical conditions for Fabry-Pérot resonances and "magic" angles, and analyse the resulting interference pattern. Numerical results demonstrate the angular dependence of transmission induced by the magnetic field.
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General Relativity and Quantum Cosmology

Action based approach to dissipative relativistic fluid systems

G.L. Comer, N. Andersson, T. Celora et al. (+1 more)

We develop an action principle for a relativistic two-fluid system with dissipation. The specific constituents of the model - which serves as a proof of principle - are particles and entropy. The linchpin of the action is the assertion that a given flux is dissipative if its covariant divergence is non-zero. For our model, the particle flux is taken to be conservative while the entropy flux is dissipative. This allows for a "top-down" approach where the general question is geometric. Previous work has shown that new terms (the proper time derivative of matter space "metrics") must be included in the Lagrangian in order to produce equations of motion with terms representing bulk and shear viscosity. In addition to including these terms we show that further terms - interpreted as velocities - can be included. The new action-based model recovers known relativistic formulations of the Cattaneo equation, which results in causal heat propagation. We further advance our understanding by exploring the single-fluid limit by locking the entropy four-velocity to that of the matter component. This reduces the system to a single field equation along with a constraint equation. We show that this constraint leads to a dynamical extension of the standard Tolman red-shift condition. Finally, we provide three example actions (of increasing complexity) which demonstrate that the model is able to reproduce (in the single-fluid limit) the anticipated terms from the relativistic Navier-Stokes equations. In the general case, the action based approach allows for a much richer structure, which may be relevant for realistic models of non-linear dissipative relativistic fluid systems.
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All authors G.L. Comer, N. Andersson, T. Celora, I. Hawke

Quantum Physics

Coherent Control of an Embedded Bound State Without a Spectral Gap

Yue Chang

Bound states in the continuum (BICs) can confine photonic excitations in open systems without conventional cavities or band gaps, making them natural candidates for long-lived quantum storage and single-photon control. Their use is limited, however, by two obstacles: they are dark to incident photons, and they lack spectral-gap protection from the surrounding continuum. We overcome both limitations in a giant atom coupled to a one-dimensional waveguide using two temporal control knobs. Atomic-frequency modulation breaks and restores the destructive-interference condition, enabling deterministic capture and release of mode-matched single photons. Coupling modulation instead preserves the BIC condition while tuning the atomic and photonic weights of the stored state. A key result is that this embedded state can nevertheless be controlled adiabatically despite the absence of a spectral gap, with an intrinsic leakage probability linear in the ramp rate. By separating radiative access from BIC-preserving deformation, the protocol turns a dark BIC into a single-photon memory whose fidelity is set by the intrinsic continuum-induced leakage law, providing a route to embedded-state control in open photonic platforms.
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Materials Science

Surface Induced Magnetism of CdSe Quantum Dots: A DFT Study

G. Kurian, D. Subedi, A. Aniagboso et al. (+1 more)

Surface induced magnetism of quantum dots is not well understood and has been a subject of considerable controversy because of the complexity of surface chemistry of quantum dot facets coupled with the many degrees of freedom inherently involved in magnetism. We performed spin-polarized colinear density functional theory calculations to study charge and spin densities to determine surface reconstructions in bare as well as passivated quantum dots in controlled way. We find that tricoordinated surface atoms relax contributing no dangling bonds and bi-coordinated atoms dimerize, reducing the population of the dangling bonds affecting the induced magnetism. As a result, bicoordinated rather than tricoordinated surface atoms are responsible for spin polarized surface states. In light of recent advanced experimental tools, we predict dangling bonds that remain, despite passivation, on low index facets with bicoordinated atoms could result in tunable surface magnetism. Our results also shed light on the contradicting experimental results in the literature.
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All authors G. Kurian, D. Subedi, A. Aniagboso, M. D. Mochena

Solar and Stellar Astrophysics

Observational Evidence of Solar Spicules Associated with Microfilament Eruptions Using DKIST

Qifan Dong, Xiaoli Yan, Zhike Xue et al. (+8 more)

The formation mechanism of spicules is fundamentally important for understanding mass and energy transport from the chromosphere into the corona. Recent studies suggested that spicules may be powered by microfilament eruptions. However, direct observational evidence remains limited due to insufficient spatial resolution. Using high-resolution H$\alpha$ broadband observations from the Visible Broadband Imager (VBI) onboard the Daniel K. Inouye Solar Telescope (DKIST), we identify 30 spicule events triggered by microfilament eruptions in a quiet Sun region near the solar disk center on 2023 August 29. The detected microfilaments have an average length of $0.93\pm0.46$ Mm and a minimum length of 0.17 Mm, substantially smaller than previously reported minifilaments. We identify two distinct morphological classes of ejecta: individual spicules associated with smaller microfilaments, and enhanced spicular activities associated with larger microfilaments. Moreover, some events exhibit apparent twisting motions. All these high-resolution observations provide compelling evidence that spicules can be triggered by microfilament eruptions.
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All authors Qifan Dong, Xiaoli Yan, Zhike Xue, Liheng Yang, Jincheng Wang, Yadan Duan, Zhe Xu, Yian Zhou, Xinsheng Zhang, Zongyin Wu, Guotang Wu

Astrophysics of Galaxies

Galaxy groups within voids

M. Argudo-Fernández, G. Torres-Ríos, P. Vásquez-Bustos et al. (+18 more)

In this work, we aim to identify and characterise a sample of galaxy groups within voids in the local Universe (z\,<\,0.08), taking into account the peculiarities of these vast and empty structures. The void galaxies used in this study are selected from a well-defined void galaxy sample, from which the parent sample of the Calar Alto Void Integral-field Treasury surveY (CAVITY) legacy project was drawn. To identify galaxy groups, we applied a fiends-of-friends (FoF) like group finder algorithm to the selected sample, ensuring a certain degree of gravitational binding among group members. The same algorithm has been applied to identify a control sample of groups not in clusters nor voids, referred as NCNV groups. The catalogue of groups consists on 1367 physically bound groups, with a total of 3040 galaxies, plus 14672 galaxy singlets. Most of the galaxies in voids are singlets (59%), in contrast, most of the NCNV galaxies in the control sample are in groups (60%). To consider the dynamical stage of the groups we used the parameters harmonic radius ($\rm R_H$), radial velocity dispersion ($\rm \sigma_{v_r}^2$), dimensionless crossing time ($\rm H_0 t_c$), and group virial mass ($\rm M_{vir}$). We also used the total optical ($r$-band) luminosity, L$_r$, to estimate the mass-to-light ratio ($\rm M/L$) of the groups. We studied the relations of void properties and these parameters with the group richness. Galaxy groups can be found in any void in the local Universe, with no dependency of group richness on the density of voids. The densest groups in the studied sample of voids are composed of six galaxies, therefore, voids generally contain small groups, in comparison to denser structures such as filaments, walls, and galaxy clusters. Galaxy groups within voids are typically loose groups, in an early stage of their evolution.
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All authors M. Argudo-Fernández, G. Torres-Ríos, P. Vásquez-Bustos, S. Verley, I. Pérez, S. Duarte Puertas, A. Jiménez, R. García-Benito, A. Zurita, M. Alcázar-Laynez, B. Bidaran, A. Conrado, D. Espada, E. Florido, R. González Delgado, M. Hernández-Sánchez, I. del Moral-Castro, J. Román, L. Sánchez-Menguiano, S. Subramanian, P. Villalba-González

Astrophysics of Galaxies

TOPoS VII. Age-metallicity relation in the Galactic halo and assembly of the Milky Way

P. Bonifacio, Y. Lebreton, I. Koutsouridou et al. (+8 more)

One technique for determining stellar ages is to compare the position of a star in the Hertzsprung-Russell diagram to theoretical stellar evolutionary tracks. The sub-giant evolutionary stage is the one that is most sensitive to age and allows the most precise evolutionary age estimates. The TOPoS sample of stars with metallicities derived from low-resolution Sloan Digital Sky Survey spectra contains a large subset of sub-giant stars with precise parallaxes from the Gaia mission, for which evolutionary ages can be determined. Our aim is to use this stellar sample to investigate the age-metallicity relation in the Galactic halo. We use the Bayesian inference code SPInS and theoretical BaSTI stellar evolutionary tracks to determine the ages for TOPoS stars. There is a clear increase in metallicity with decreasing age, albeit with a considerable scatter at any given age. At ages larger than 8 Ga, the scatter is so large that in fact, over this range, age and metallicity appear to be uncorrelated. At any given age, the metallicity distribution is multi-modal, with up to three distinct peaks. These peaks trace three age-metallicity relations that we tentatively identify with the halo, thick-disc, and thin-disc. Our data demonstrate the important role of mergers in the evolution of the Galaxy, up to 8 Ga ago. In more recent times, the spread in metallicity drops. One possibility is that the major merger Gaia-Sausage-Enceladus may have perturbed the galaxies in the Milky Way vicinity in such a way as to decrease the merger rate. Chemical evolution models and cosmological models of the Local Group both support the importance of mergers in the early evolution of the Milky Way. Larger, unbiased samples, or at least with well-understood biases, of stars with accurate ages are required for a quantitative comparison between models and data.
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All authors P. Bonifacio, Y. Lebreton, I. Koutsouridou, Y. Zou, D. Romano, S. Salvadori, L. Sbordone, L. Monaco, E. Caffau, M. Spite, P. François