Cosmology and Nongalactic Astrophysics
Field-level inference of growth rate from DESI BGS galaxy and ZTF supernova simulations
Corentin Ravoux, Bastien Carreres, Julian Bautista et al. (+60 more)
Galaxy peculiar velocities are a powerful probe of the growth rate of structure $f$ at low
redshifts ($z < 0.2$), measured through the combination $f\sigma_8$. These constraints are improved by combining peculiar velocities with
redshift space distortion measurements from the
galaxy density field. We create a dedicated simulation to test growth rate measurement from the combination of Type Ia
supernova peculiar velocities from the Zwicky Transient Facility (ZTF) with the Bright
Galaxy Survey (BGS) of the Dark Energy Spectroscopic Instrument (DESI), using projections for 6 years of ZTF data and the Data Release 3 (DR3) of DESI. We apply a wide-angle likelihood-based field-level inference to combine ZTF velocity and DESI BGS density fields simultaneously. This procedure is performed while varying the different density and velocity field configurations. Adding DESI
galaxy density information to the ZTF
supernovae improves the constraint on nuisance parameters and yields up to a 50 % reduction in the growth-rate uncertainty without introducing bias. If we consider the conservatively best DESI density configuration, the mean error bar achievable by a DESI ZTF measurement is $\sigma_{f\sigma_8} = {}^{+0.047}_{-0.048}$ corresponding to a 10 % error. These measurements will play a critical role for testing modified
gravity theories.
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All authors Corentin Ravoux, Bastien Carreres, Julian Bautista, Damiano Rosselli, Jessica Aguilar, Steven Ahlen, Melissa Amenouche, Uendert Andrade, Eric Armengaud, Alejandro Aviles, Florian Beutler, Davide Bianchi, David Brooks, Umut Burgaz, Aurelio Carnero Rosell, Edmond Chaussidon, Todd Claybaugh, Andrei Cuceu, Axel de la Macorra, Georgios Dimitriadis, Andreu Font-Ribera, Daniel Felipe Forero Sánchez, Jaime E. Forero-Romero, Enrique Gaztañaga, Satya Gontcho A Gontcho, Ariel Goobar, Gaston Gutierrez, Hiram K. Herrera-Alcantar, Cullan Howlett, Mustapha Ishak, Joel Johansson, Stephanie Juneau, Ofer Lahav, Martin Landriau, Laurent Le Guillou, Alexie Leauthaud, Marc Manera, Ramon Miquel, Seshadri Nadathur, Jakob Nordin, Hernan Enrique Noriega, Enrique Paillas, Nathalie Palanque-Delabrouille, Will Percival, Francisco Prada, Ignasi Pérez-Ràfols, Mickael Rigault, Antoine Rocher, Philippe Rosnet, Graziano Rossi, Rossana Ruggeri, Lado Samushia, Eusebio Sanchez, Christoph Saulder, David Schlegel, Michael Schubnell, Hee-Jong Seo, Joseph Silber, Małgorzata Siudek, Mathew Smith, Gregory Tarlé, Benjamin A. Weaver, Pauline Zarrouk
High Energy Physics (Experiment)
Using Graph Neural Networks for the segmentation of overlapping objects in high granularity calorimeters
Matthieu Melennec and Frédéric Magniette
High-granularity calorimeters at the High-Luminosity LHC require novel
algorithms to resolve overlapping particle showers. We present an optimised Graph Neural Network (GNN)
segmentation block that predicts node-level energy fractions to disentangle overlapping two-
photon showers. By accelerating graph construction and convolution operations, our pipeline achieves competitive separation efficiency with significantly reduced algorithmic complexity.
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Strongly Correlated Electrons
Electronic and topological properties of Ce-based honeycomb ferromagnet Ce$_2$Zn$_6$Ge$_3$
Yanen Huang, Zihan Yang, Jiawen Zhang et al. (+7 more)
Ce$_2$Zn$_6$Ge$_3$ is a rare example of the Ce-based honeycomb ferromagnet. Here, we report its
Fermi surface and topological properties by
quantum oscillations via the magnetoresistance and tunnel diode oscillator (TDO) based measurements, in combination with the density functional theory (DFT) calculations. Four fundamental frequencies are observed in the
quantum oscillations, and their angle dependence is more compatible with the DFT calculations assuming that the 4$f$-electrons are localized, suggesting a localized nature of ferromagnetism in Ce$_2$Zn$_6$Ge$_3$. Furthermore, the observations of negative longitudinal magnetoresistance and non-zero Berry phase, as well as the existence of two pairs of Weyl points near the
Fermi level as revealed from the calculated electronic structures, provide strong evidence for nontrivial
topology in Ce$_2$Zn$_6$Ge$_3$. These findings suggest that Ce$_2$Zn$_6$Ge$_3$ could provide a unique platform to study magnetism,
topology,
quantum criticality and their interplay.
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All authors Yanen Huang, Zihan Yang, Jiawen Zhang, Yuwei Zhou, Lubin Wang, Gang Li, Michael Smidman, Chao Cao, Yu Liu, Huiqiu Yuan
Optics
Contact lens with stretchable distributed-feedback laser for intraocular pressure monitoring
S.A. Ivanov, I.M. Fradkin, E.S. Musikhina et al. (+8 more)
Continuous monitoring of intraocular pressure (IOP) is essential for the diagnosis and management of glaucoma, yet existing clinical methods rely on intermittent in-clinic measurements that miss critical diurnal fluctuations. Smart contact lenses are an attractive platform for continuous IOP tracking, and optical strain sensors are particularly promising thanks to their high sensitivity and natural readout. Most such optical sensors infer strain from the period of a regular structure - a grating or photonic
crystal - whose deformation is read out optically. However, the precision of all sensors based on the period of regular structures is fundamentally bounded by the uncertainty principle, which severely limits performance at the millimeter length scales available inside a contact lens. Here, we address this limitation by integrating a distributed-feedback (DFB)
laser, based on a surface-modulated ultrathin F8BT dye layer, into a soft polydimethylsiloxane (PDMS) contact lens. Operating at a
symmetry-protected bound state in the continuum at the {\Gamma} point, the device produces a narrow lasing line whose wavelength shifts directly with grating strain - a quantity not constrained by the spatial uncertainty principle. The DFB structure is fabricated by UV
holographic lithography and transferred onto the lens by a simple float-off process, yielding a stretchable, transparent,
polymer-compatible sensor that is intrinsically scalable. Tested on a custom artificial eye model whose pressure-induced deformation is comparable in scale to that reported for the human eye, the sensor achieves a sensitivity of 0.027 nm/mmHg and a calibration residual of 1.2 mmHg under phantom conditions, a level relevant to tonometric monitoring, with substantial headroom currently limited mainly by auxiliary readout equipment.
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All authors S.A. Ivanov, I.M. Fradkin, E.S. Musikhina, R.V. Kirtaev, A.A. Khrebtov, A.A. Vyshnevyy, A.A. Marchenko, V.R. Solovei, I.P. Radko, A.V. Arsenin, V.S. Volkov
Statistical Mechanics
Fluctuations and multifractality in stochastic models of interface growth and population dynamics
Maximilien Bernard
This thesis studies how disorder and fluctuations shape large-scale growth phenomena in three related settings: fluctuating interfaces, random spring chains, and random multiplicative growth. The first part concerns interface growth and a phenomenon denoted anomalous scaling, where local and global exponents differ.To clarify its origin, we study two models in which this mismatch has different causes. The first is a heterogeneous elastic line, where we show that the apparent anomaly is a purely statistical effect. The second is the
stochastic porous medium equation, a strongly nonlinear model in which the anomaly is genuine. The second part concerns Anderson localization, which appears here through the spectral properties of the heterogeneous elastic lines. We study chains with both random masses and random spring constants, with particular emphasis on the strong-disorder regime, where standard weak-disorder expansions break down. We develop a new combinatorial method to probe this regime. The last part concerns random multiplicative growth with redistribution. In such models, changes in wealth, population, or mass, for instance, are proportional to the amount already present, so that small differences are amplified over time. This naturally generates broad distributions and provides a simple mechanism for the emergence of inequality and concentration, with applications to population dynamics, wealth distribution, city growth, and ecology. We in particular study models in which each site has its own quenched growth rate, representing a persistent advantage or disadvantage, and is also subject to transient fluctuations. Redistribution competes with these mechanisms by homogenizing the system. This competition leads to rich phase diagrams.
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General Relativity and Quantum Cosmology
Charged Simpson-Visser-AdS spacetime: QPOs and observational constraints
Saeed Ullah Khan, Javlon Rayimbaev, Muhammad Zahid et al. (+3 more)
In this article, we examine particle dynamics and Quasi-periodic oscillations within a charged Simpson-Visser-Anti-de Sitter (AdS) spacetime. We first analyze the behavior of the metric and black hole horizons under the competing impact of electric charge $Q$, regularization parameter $b$, and AdS radius $l$. The roots of the metric function reveal transitions between three distinct topological classes: non-extremal configurations featuring distinct inner and outer horizons, extremal limits with a single degenerate horizon, and strictly positive, horizonless wormhole geometries. By evaluating the effective potential, we determine how this modified geometry shifts the Innermost Stable Circular Orbit (ISCO) and alters the angular momentum and energy of test particles. Moreover, we derive the Keplerian, radial, and vertical frequencies to model quasi-periodic oscillations (QPOs). We show that the interplay between the regularization parameter $b$ and the AdS radius $l$ significantly modifies twin-peak QPOs. In particular, $b$ drives fundamental QPO frequencies higher than those predicted by standard general relativistic backgrounds. Twin-peak high-frequency QPO data from two black-hole binaries disfavor the Schwarzschild limit at $\sim\!4\sigma$, but constrain only a degenerate combination of charge and AdS
curvature, leaving the regularization parameter entirely unconstrained by the data.
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All authors Saeed Ullah Khan, Javlon Rayimbaev, Muhammad Zahid, Tolaniddin Nurmukhamedov, Abat Muratov, Weiwei Wang
Astrophysics of Galaxies
Discovery of Kolmogorov-like turbulence in the inner shell of SNR HB 9
Li Xiao, Ming Zhu, Xiao-Hui Sun et al. (+2 more)
We investigated the scaling relation of the magnetohydrodynamic
turbulence in the inner and outer shells of the
supernova remnant HB 9 using multi-tracers. For the eastern inner shell section, one-dimensional structure function and power spectrum analyses of the
radio total intensity, H-alpha emission, and polarized intensity consistently show a Kolmogorov-like scaling of l^2/3 over the inertial range. The two-dimensional power spectrum for the entire inner region follows k^-8/3 of all tracers, including the polarization gradient. It indicates that fully developed, trans-Alfvenic Kolmogorov
turbulence is present in the inner shell of HB 9. We estimated the strength of random
magnetic field therein from the low fractional polarization (5%), and obtained a upper limit delta B of 18 micro G. The
turbulence in the inner shock shell is most likely driven by the Richtmyer-Meshkov instability.
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All authors Li Xiao, Ming Zhu, Xiao-Hui Sun, Wolfgang Reich, Patricia Reich
Earth and Planetary Astrophysics
Planets Around Solar Twins/Analogs (PASTA) III: Chemical Clock Relations in Planet-Hosting Solar Analogs
Qinghui Sun, Serat M. Saad, Yuan-Sen Ting et al. (+10 more)
Context. Abundance ratios between elements synthesized on different nucleosynthetic timescales provide empirical chemical clocks for estimating
stellar ages, but robust calibrations require homogeneous samples with precise
stellar parameters and elemental abundances. Aims. We aim to investigate whether the presence of
planets modifies empirical chemical clock relations. Methods. We present high-precision
stellar parameters and elemental abundances for 52 new
planet-hosting targets observed with Keck/HIRES, LBT/PEPSI, and Subaru/HDS. Combined with PASTA I and II, the full sample comprises 94
stars, of which 81 are identified as
planet-hosting
solar twins and analogs, and is used to characterize
Galactic chemical
evolution and derive empirical chemical clock relations. Results. We recover the expected
Galactic chemical
evolution trends, with $\alpha$-elements such as Mg and S increasing with
stellar age, while s-process elements such as Y, Ba, and Sr show negative age correlations. In contrast, Fe-peak elements and the r-process element Eu show little or no significant age dependence. These trends give rise to tight chemical clock relations based on [Y/Mg], [Y/Al], [Ba/Mg], [Ba/Al], and [Sr/Mg], with [Y/Mg] and [Y/Al] providing the strongest correlations. [Ba/Al] shows the steepest age dependence, and the Ba-based ratios are generally more sensitive to age than their Y-based counterparts. Conclusions.
Planet-hosting
solar analogs follow chemical-clock relations consistent with those of nearby
solar twins, with no evidence for a significant
planet-related effect. The derived relations are primarily applicable to local
solar twins and analogs in the
Galactic thin disk.
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All authors Qinghui Sun, Serat M. Saad, Yuan-Sen Ting, Jiayue Zhang, Chenyang Ji, Fei Dai, Sharon Xuesong Wang, Bryant Randolph, Yunzhe Gu, Ilya Ilyin, Yaguang Li, Jie Yu, Fan Liu
Quantum Physics
Excitation Gap of a Confined Chiral Mode Measures Critical Zero-Point Fluctuations
Shu He and Liwei Duan
Where uniform and
chiral superradiant boundaries meet in a
quantum Rabi ring, the quadratic theory leaves a degenerate
chiral ladder with finite radial width. We show that adding one
chiral quantum widens the ladder's radial wave function; the quartic coupling then raises the uniform quadratic coefficient. The resulting gap is proportional to the uniform zero-point variance divided by the atomic-to-cavity frequency ratio $\eta$: it closes as $\eta^{-2/3}$ while the variance grows as $\eta^{1/3}$. A quartic Schrödinger equation fixes both observables and the first correction to their ratio, as confirmed by full
spin-
photon diagonalization. A triangle of collective
spins with Dzyaloshinskii-Moriya exchange obeys the same relation, with a different coefficient and a correction of opposite sign. The ring's three-coordinate spectrum connects this gap to the neighboring $\eta^{-1}$ and $\eta^{-1/3}$ laws and to
photon-number saturation.
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Quantum Physics
Quantum Security of XOR of Permutations via Fourier Analysis
Wonseok Choi, Minki Hhan and Junyoung Jang
The XOR of two or more independent random permutations (XoP) is the prototypical pseudorandom function built from permutations achieving security beyond the birthday bound. The classical security of the XoP construction is well established, but its security against
quantum attacks that query XoP in superposition has remained widely open. We prove that the XOR of $r\ge 2$ random permutations over $\{0,1\}^n$ is indistinguishable from a random function by any $q$-query
quantum algorithm with advantage \[O\left(\min\left\{\frac{q^3}{2^{rn}},\frac{q^{1.5}}{2^{(r-0.5)n}},\frac{1}{2^{(r-1.5)n}}\right\}\right)\] for all $q\ll 2^n$. In particular, XoP remains secure throughout the entire query range, far beyond the $2^{n/3}$ bound due to
quantum collision finding attacks. This is the first construction from permutations that achieves the
quantum version of the beyond birthday bound security. We also present several heuristic attacks suggesting the tightness of our bounds in ranges $q\le 2^{n/2}$ and $\approx 2^n$. We use a
Fourier-analytic variant of the
polynomial method: the advantage of any $q$-query
quantum algorithm is controlled by the
Fourier components of degree at most $2q$, or by $2q$ input-output data of the construction. The norms of most components are bounded well, proving the bound $2^{-(r-3/2)n}$. The norm of low-degree components turn out to be too large for the bounds $q^3/2^{rn}$ and $q^{1.5}/2^{(r-0.5)n}$. We reinterpret these low-degree components as (sums of) advantages of the other problems. For example, the degree-2 and degree-4 terms are interpreted as the advantages against random functions with and without planted collisions, which in turn are bounded using Zhandry's small-range distributions. Along the way, we prove a new bound for the small-range indistinguishability for (ironically) large ranges, which is of independent interest.
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Quantum Physics
Coherence Rather Than Error Rate Governs Privacy in Multi-Tenant Quantum Computing
Farhad Farokhi
Multi-tenant computing enables providers of commercial cloud
quantum processors to rent disjoint sectors of a device to independent users. Average gate error, which cloud
quantum computing providers report, does not determine how much one tenant learns about another. We propose an information-theoretic notion of information leakage across co-tenancy boundaries stemming from
quantum state distinguishability. We measure this leakage on commercially-available 156-
qubit (IBM Kingston) and 20-
qubit (IQM Garnet) devices. Boundaries with identical benchmarked error can offer significantly different amount of information leakage because standard reported measures of error are blind to coherent-versus-
stochastic nature of the error while the proposed notion of information leakage is not. A uniform Pauli randomisation implemented over the victim's whole register is used as a defence mechanism to reduce the information leakage to zero. The defence theoretically does not incur a fidelity cost, but the experiments show a non-trivial degradation caused by accumulation of errors. We provide a specific call-for-action to the providers of
quantum cloud computing to report information leakage in addition to standard error rates in their device datasheet to enable users to compute
privacy and security risks prior to engagement with the device.
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High Energy Astrophysical Phenomena
Gravitational Waves from Core-Collapse Supernovae: Dependence on the Progenitor Star, Rotation Rate and Nuclear Equation of State
Jade Powell, Bailey Sykes and Bernhard Müller
We simulate 137 axisymmetric core-collapse
supernova explosions to systematically investigate the impact of different progenitor properties, rotation rates, and equations of state on the
supernova gravitational-wave emission. We use 15 different progenitor
stars, with masses ranging from $9.71\,\mathrm{M}_{\odot}$ to $36.61\,\mathrm{M}_{\odot}$, three equations of state, and three rotation rates, with durations extending up to 5.5\,s after bounce. We find substantial differences in the gravitational-wave emission between equations of state, with the CMF equation of state producing lower gravitational-wave amplitudes and a longer low frequency mode due to the standing
accretion shock instability that remains visible even at $\sim5$\,s post bounce. Rapid rotation also significantly alters the gravitational-wave signal, with more visible modes in the gravitational-wave emission, and lower energies due to later shock revival times. We include the gravitational-wave emission due to
neutrino memory, and show it can significantly improve the detectability of core-collapse
supernovae for observatories with improved low frequency sensitivity. We propose a recalibration of universal relations for the high frequency mode, using fits to our waveforms, that reduces the fit error at late times in the gravitational-wave signal. Finally, we investigate, for the first time, the impact of random seed perturbations on the gravitational-wave emission. We find that
stochastic perturbations can produce dramatic variations in gravitational-wave amplitude, and can alter the signal-to-noise ratio of a detection by as much as 62% for models close to the boundary between failed and successful shock revival.
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Mathematical Physics
Discontinuity of Continuum Fermion Dynamics
Oliver Siebert
We study the Heisenberg dynamics of continuum
fermions in $\IR^d$ interacting through a pair potential. For a large class of nonconstant pair potentials and under suitable assumptions on the dispersion relation and external potential, we prove that the dynamics fails to be pointwise-norm continuous even on the gauge-invariant CAR
algebra. An automatic-continuity argument then shows that neither the CAR
algebra nor its gauge-invariant subalgebra is invariant under the dynamics, with non-invariance occurring for almost all times.
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General Relativity and Quantum Cosmology
Avoided crossings and resonances in black hole ringdown with coupled fields: A case study of the Einstein-Maxwell-axion system
Takuya Takahashi, Hayato Motohashi and Kazufumi Takahashi
Avoided crossings in black hole quasinormal-mode (QNM) spectra exhibit characteristic resonant properties, including enhanced excitation factors. We extend the study of this phenomenon to perturbation systems with multiple coupled fields and investigate its consequences for ringdown waveforms. As a concrete example, we consider a charged black hole in the Einstein-Maxwell-
axion system, whose QNM branches can be classified according to the gravitational, electromagnetic, and
axion modes to which they continuously connect in the decoupling limit. We focus on an avoided crossing between the
gravity- and electromagnetic-led branches thus defined. We verify that the QNM reconstruction accurately reproduces the ringdown portion of the directly evolved time-domain waveform. Near the avoided crossing, an effectively slower decay emerges for particular initial perturbations, while the resonantly enhanced contributions from the two QNMs largely cancel in the physical waveform. The QNM decomposition further reveals an exchange of the physical characters of the two branches across the resonance. These results characterize the imprint of resonances on black hole ringdown in systems with multiple coupled fields.
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Quantum Physics
Observation of a topological defect state in the quantum Rabi model
Kyungmin Lee, Jiyong Kang, Sunkyu Yu et al. (+3 more)
Synthetic
lattices built from hybrid
qubit-oscillator systems provide a platform for exploring
topology, with multiple physical degrees of freedom enabling control over
lattice geometry. A single
spin-oscillator pair, described by the
quantum Rabi model, provides a minimal system supporting a topological defect state on a
lattice formed from the oscillator's infinite ladder of number states. However, the realization of the defect state and its robustness remain experimentally unexplored. Here we realize a topological defect state of the
quantum Rabi model in a single trapped $^{171}\mathrm{Yb}^{+}$ ion. As a coupling phase varies, reconstructed phase-space distributions yield centroid trajectories with windings of one and zero in two regimes, linking discrete-
lattice topology to the geometry of the oscillator's continuous position-momentum space. The measured
spin response to drive-amplitude modulation relates the stability of
spin polarization to energy gaps and allowed transitions. Together, these results establish a minimal
quantum system for realizing and probing topological defect states.
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All authors Kyungmin Lee, Jiyong Kang, Sunkyu Yu, Jaehun You, Wonhyeong Choi, Taehyun Kim
Fluid Dynamics · Cross-listed from math.AP
A Critical Value for the Viscosity Coefficient: Triggering Oscillatory Traveling Waves in the Pseudo-parabolic Fisher-KPP Equation
Yang Cao, Haomeng Chen, Chunhua Jin et al. (+1 more)
The pseudo-
parabolic term $u_{xxt}$ serves as a canonical example of higher-order viscosity that provides effective regularization while capturing the refined physical mechanism. How it alters the dynamics of prototype equations remains a fundamental issue, which is not yet fully understood. The goal of this paper is to show that this term induces a sharp transition in traveling wave structure, via studying the pseudo-
parabolic Fisher-KPP equation $$ u_t - \tau u_{xxt} = D u_{xx} + u(1-u). $$ We completely characterize how the parameter ratio $\tau/D$ acts as a critical switch: it preserves the monotonic structure of classical traveling waves when $\tau/D \leq 1$, yet it triggers a qualitative shift to oscillatory traveling waves when $\tau/D > 1$. Numerical simulations support these findings. The threshold $\tau/D=1$ thus captures the dual role of the pseudo-
parabolic term: it acts as a structure-preserving viscosity when small, but when large it reflects dominant capillary hysteresis, generating the oscillations that explain the saturation overshoot, a phenomenon that contradicts classical
diffusion models yet is widely observed in two-phase flow.
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All authors Yang Cao, Haomeng Chen, Chunhua Jin, Jingxue Yin
Quantum Physics
Cavity magnonics and bound states in the continuum with Bragg and anti-Bragg mirrors
B.-Y. Wu, K.-P. Li, G. Chen et al. (+7 more)
A periodic resonant emitter array coupled to a one-dimensional waveguide can act as a mirror. A typical example is a Bragg mirror, where emitters are spaced by multiples of half wavelengths and collectively enhance light reflection. Two such mirrors form an effective cavity that hosts bound states in the continuum (BICs). However, generating and detecting the spatial profiles of such BICs has proven challenging. Here, we experimentally demonstrate BICs in cavity magnonics using two periodic ferrimagnetic-sphere arrays and a probe sphere in a dual-open-waveguide architecture. We realize both Bragg and anti-Bragg cavities, whose mirrors have different
lattice constants. In the Bragg cavity, there are degenerate supermodes formed by mirror spheres. We show that a single dark supermode coherently couples to the probe
magnon in the cavity region, forming two polaritons whose splitting scales with both the probe-sphere size and the number of mirror spheres. By contrast, the anti-Bragg cavity has bright and dark supermodes in a bandgap, substantially changing the
magnon-cavity interaction. Moreover, by moving the probe sphere, we perform position-dependent detection of the cavity field, highlighting the role of BICs in these cavities. Our flexible experimental setup with a scanning probe opens possibilities to detect other exotic states created by light-matter interaction, to interface with superconducting
circuits in hybrid
quantum networks, and to study non-Hermitian physics with Bragg and anti-Bragg cavities.
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All authors B.-Y. Wu, K.-P. Li, G. Chen, W.-M. Zhou, C.-X. Run, K.-M. Hsieh, A. F. Kockum, Z.-R. Lin, W. Nie, I.-C. Hoi
High Energy Physics (Phenomenology)
Next-to-Next-to-Leading Order QCD Corrections to $\eta_t \to HZ$
Cai-Ping Jia, Yan-Qing Ma, Huai-Min Yu et al. (+1 more)
Motivated by recent LHC observations of a threshold enhancement in the $t\bar t$ system consistent with toponium-like dynamics, we compute the next-to-next-to-leading order (NNLO) QCD correction to the hard short-distance coefficient for $\eta_t\to HZ$, where $\eta_t$ denotes the pseudoscalar color-singlet configuration $t\bar t({}^1S_0^{[1]})$. Within the NRQCD factorization framework, we retain the full dependence on the
Higgs- and $Z$-
boson masses and include both the two-loop virtual corrections and the real double-
gluon-emission channel. At next-to-leading order (NLO), the finite-mass result remains close to its large-mass limit. The NNLO coefficient develops logarithms of both the renormalization scale $\mu_R$ and the NRQCD factorization scale $\mu_\Lambda$. For $\mu_R=\mu_\Lambda=m_t$, the NLO and NNLO terms suppress the leading-order width by about $29\%$ and $19\%$, respectively; the two-loop contribution is about two thirds of the one-loop effect and of the same sign, so the perturbative series converges slowly and the NNLO prediction amounts to about $52\%$ of the leading-order width. The resulting coefficient provides a necessary ingredient for future threshold studies of $\eta_t\to HZ$ and for assessing the sensitivity of this channel to the top-
Higgs interaction. The accuracy of the result is further supported by three checks: reproduction of the known large-mass limit at one loop, independence of the extracted coefficient on the $\gamma_5$ prescription, and consistency of its scale logarithms with the renormalization-group structure.
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All authors Cai-Ping Jia, Yan-Qing Ma, Huai-Min Yu, Yu-Jie Zhang
Solar and Stellar Astrophysics
Numerical analysis of electron density and response time delay during solar flares in mid-latitudinal lower ionosphere
Sayak Chakraborty and Tamal Basak
Impacts of
solar flare vary at different parts of the lower ionosphere depending on its proximity to the direct exposure of incoming
solar radiation. The quantitative analysis of this phenomenon can be attributed to the
solar zenith angle (chi(t)) profile over the ionosphere. We numerically solve the electron continuity equation to obtain the lower ionospheric electron density profile (Ne(t)). The electron production rate (q(t)) is governed by the (i) X-ray profile (phi(t)) of the
flare, (ii) chi(t)-values during the
flare occurrence, etc. For analyzing the X-ray profile during
flares, we use the GOES-15 satellite observations. Since we are working on an electron continuity equation based simplified ionospheric model, we confined our analysis to the comparatively stable mid-latitude ionosphere only. We choose three
flares each from C, M, and X-classes for Ne(t)-profile computation. We observe that temporal Ne(t)-profiles differ when computed for the lower ionosphere over different discrete latitudes. Further, we compute the spatial Ne(t)-profile across the mid-latitude region at the time when phi(t) = phi_max. Now we assume that these
flares repeat themselves every day of a year (DoY) at the same time of a day and we compute Ne(t)-profiles for each day. We found a seasonal effect on the Ne(t)-profile due to
solar flare. Further, we investigate the response time delay (Delta t) of the lower ionosphere, which is the time difference between incidence of X-ray and the respective change in Ne(t)-profiles during
solar flares. Strong seasonal effects on Ne(t)-profile and Delta t are the unique results of this work.
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Astrophysics of Galaxies
R Coronae Borealis fadings: a dusty gas cloud eclipse model
Mark A. Walker, Artem V. Tuntsov and Arthur G. Suvorov
R Coronae Borealis
stars (RCBs) are hydrogen-deficient supergiants that undergo deep fading events due to transient extinction by
dust. First observed over two centuries ago, that behaviour remains poorly understood. Our aim is to investigate the possibility that the fading events are eclipses by orbiting, dusty gas clouds. We construct a simple physical model of the
dust wind that is driven from the cloud surface by the
stellar radiation field, and we calculate the extinction and scattered light from wind and cloud. We consider a broad range of
dust compositions. For the model that best matches the data, we sketch out implications for the RCB phenomenon more broadly. Our calculations show that conventional
dust materials like graphite and silicate produce eclipses whose ingress is too slow and whose morphology too symmetric to account for RCB fadings. But
dust made of solid H2 yields a good match: the eclipses are deep and strongly asymmetric, with rapid onset and slow recovery, and event timescales are about right if the clouds' periastra are within a few tens of AU. Such close approaches imply
tidal stripping/disruption of each cloud, with hydrogen-deficient debris accreting onto the
star via a disk. Starlight incident on the disk creates a metal-ion
plasma that emits a powerful bremsstrahlung continuum, peaking in the mid-IR. We conclude that eclipses by orbiting, dusty clouds could be the cause of RCB fading events, but only if the
dust is made of solid H2, in which case both the unusual, hydrogen-deficient nature of the
stars and their mid-IR excess follow naturally. It is, however, challenging to account for the high eclipse rates that are observed; we propose a scenario in which the progenitor
star is a wide binary inside a massive
halo of clouds, suggesting a connection to the
Galactic "missing mass" problem.
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Mesoscale and Nanoscale Physics
Observing Colossal and Tunable Near-field Thermal Radiation with A Highly Sensitive Annular Micro-thermocouple Junction
Ken Araki, Wei Han Won and Liping Wang
Near-field radiative heat transfer between two objects has been theoretically predicted and experimentally demonstrated to exceed far-field blackbody limit across nanoscale
vacuum gap distance enabled by evanescent surface waves coupling, while significant enhancement by more than 100 times usually requires sub-50-nm
vacuum gaps around room temperature. This is challenging for parallel-plate configuration with millimeter sample sizes due to intrinsic wafer bow and contaminant particles. Sphere-plate configuration with a microsphere attached to bimaterial cantilevers or micro-thermocouple tips has been used to experimentally demonstrate near-field radiative heat transfer down to 30-nm gaps, but it is much less developed because of the challenges in the sophisticated sensor fabrication, low sensitivity and weak signals. In this work, we overcome these challenges by an annular micro-thermocouple junction fabricated at the end of a glass fiber with straightforward thin-film deposition to achieve high measurement accuracy with large Seebeck coefficient 25 uV/K and thermal resistance 8.7e6 K/W. With a silica microsphere attached underneath the micro-thermocouple junction, we report experimental observation of colossal near-field radiation heat transfer over blackbody limit down to 10-nm gap up to 2600 times with quartz and 900 times with doped silicon. Upon phase transition of VO2 thin film emitter, tunable near-field heat transfer up to 430-fold enhancement is experimentally demonstrated at 15-nm gap with 64% reduction. Experimental data agrees well with rigorous modeling based on fluctuational electrodynamics and Derjaguin approximation, and underlying mechanism is understood by energy transmission calculations. The results will advance the experimental study and fundamental understanding of energy transport at nanoscale gaps.
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Statistical Mechanics
Second largest eigenvalue does not bound stationary entropy production
Naoto Shiraishi
We examine the spectral dissipation-coherence trade-off inequality conjectured by Oberreiter et al. [Phys. Rev. E 106, 014106 (2022)], stating that the coherent number, defined from the second largest
eigenvalue, provides a lower bound on the stationary
entropy production per unit oscillation. We disprove this
conjecture by explicitly constructing a counterexample, which accompanies finite coherent number with vanishing stationary
entropy production. This model also excludes a wide class of thermodynamic bound with the real and imaginary parts of the second largest
eigenvalue of the transition rate
matrix. Our result implies that the second largest
eigenvalue does not necessarily characterize the degree of coherent oscillation.
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Plasma Physics
Electrons with Anomalous Energy Generated in Vacuum Diodes with Different Pulse Duration
Vasily Kozhevnikov, Victor Tarasenko, Maxim Vorobyov et al. (+2 more)
This paper presents results from an experimental study in which anomalous energy electrons (AEE) appear in
vacuum diodes under varying amplitude and pulse-duration conditions. AEE refer to high-energy discharge electrons with kinetic energy $T$ exceeding $eU$ values (where $e$ is the electron charge and $U$ is the amplitude gap voltage). Here, two experimental setups were used to generate electron beams with different pulse durations. The electron energy spectra were reconstructed from the beam attenuation curves using an AI-driven methodology for solving an ill-posed inverse problem for the Fredholm equation. This confirms that
vacuum diodes generate electron beams with a significant AEE fraction (up to 25~%) only when operating with nanosecond-long voltage pulses. It has been confirmed that AEE in
vacuum is generated using nanosecond- or sub-nanosecond voltage pulses. Experiments also indicate that photoelectric absorption of bremsstrahlung cannot produce significant AEE in
vacuum discharges.
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All authors Vasily Kozhevnikov, Victor Tarasenko, Maxim Vorobyov, Evgenii Baksht, Andrey Kozyrev
Nuclear Theory
Medium effects on neutron star modified and direct Urca cooling rates
B. X. Zhou, Jin-Biao Wei, Z. H. Li et al. (+2 more)
We study the effects of in-medium modification of the elementary cooling processes on observable properties of isolated
neutron stars. We then deduce the
neutron star mass distributions compatible with the cooling analysis and compare with current theoretical models. We conclude that current cooling data require fast direct Urca (DU) cooling, moderated by
proton superfluidity, to be active in most
neutron stars, and that the DU onset threshold must lie below canonical masses. In that case medium modifications of modified Urca (MU) rates are practically insignificant, but the $nn$ Bremsstrahlung rate plays a dominant role.
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All authors B. X. Zhou, Jin-Biao Wei, Z. H. Li, G. F. Burgio, H.-J. Schulze
Astrophysics of Galaxies
Toward Resolution Convergence for Star Formation and Galactic Winds in Galaxy Simulations
Xue-Fu Li, Weishan Zhu, Tian-Rui Wang et al. (+2 more)
The predictive power of hydrodynamic simulations of
galaxies is often hampered by the resolution dependence of sub-grid models for
star formation (SF) and
stellar feedback. We present three-dimensional hydrodynamic simulations of an M82-like low-mass starburst
galaxy at resolutions of 4, 8, 16, 32 pc and develop optimized sub-grid prescriptions to mitigate these numerical inconsistencies. For
star formation, we adopt a $\sim20$ pc physical-scale control volume, corresponding to the typical size of
giant molecular clouds (GMCs), for gas
accretion onto sink particles, reducing its dependence on numerical resolution. We further incorporate an empirical, resolution- and density-dependent
star formation scheme that accounts for variations in gas surface density across spatial scales, as suggested by observations. Furthermore, we refine the
supernova feedback coupling by anchoring the injection volume to the physical cooling radius of the
supernova remnant ($R_{\rm cool}$) and utilizing a resolution-dependent thermal-to-kinetic energy partition. These improvements substantially enhance convergence across 4 to 32 pc: variations in the total
stellar mass formed and kinetic energy are reduced to $\sim20\%$, while relative errors in the cool-phase mass
outflow rate and integrated X-ray luminosity decrease to below $\sim40\%$. The warm and hot
outflow phases remain less well converged, with variations of $\sim50\%$ and $\sim75\%$, respectively. The upgraded model also improves the convergence of normalized wind properties, with relative errors below $\sim50\%$, $\sim80\%$, and $\sim20\%$ for the time-averaged mass loading factor, energy loading factor, and X-ray emission efficiency, respectively. Our results provide a practical framework for achieving more robust simulations of starburst
galaxies.
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All authors Xue-Fu Li, Weishan Zhu, Tian-Rui Wang, Huan Chen, Long-Long Feng
Quantum Physics
Observation of a topological edge state among localized bulk states in the anisotropic quantum Rabi model
Sungjoo Lim, Chanyang Im, Christopher G. Yale et al. (+7 more)
Topological phases are governed by discrete
symmetries that protect boundary modes against local perturbations. When translational periodicity is absent, the bulk states also become localized, so that a topological edge state can no longer be distinguished from them by spatial localization alone. Here, we investigate the topological edge state (TES) and bulk eigenstates of the anisotropic
quantum Rabi model (AQRM) in a trapped-ion
quantum simulator. The AQRM hosts a topological phase in a one-dimensional synthetic
lattice, whose translational
symmetry is broken by the non-uniform couplings scaling with the site index. While both the TES and bulk states show localized distributions, we find that the TES exhibits well-defined chirality and near-complete
spin–
boson separability as signatures of the topological phase, in contrast to the bulk states. Phase-space
tomography further reveals that the bosonic component of the TES is a squeezed
vacuum state, with squeezing up to 6.45 dB. These results identify the TES through its intrinsic topological signatures and establish eigenstate-level characterization as a route to probing topological phenomena.
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All authors Sungjoo Lim, Chanyang Im, Christopher G. Yale, Brian K. McFarland, Edward C. Tortorici, Daniel S. Lobser, Melissa C. Revelle, Susan M. Clark, Mahn-Soo Choi, Junki Kim
Astrophysics of Galaxies
A Study on the Evolution of NGC6822. I. Investigating the Star Formation History through Evolved Stellar Populations
Fatemeh Khatamsaz, Mahdi Abdollahi, Atefeh Javadi et al. (+4 more)
NGC6822 is an isolated
dwarf irregular
galaxy in the Local Group at a distance of $\sim$ 490 kpc . In this paper, we derived the
star formation history (SFH) of NGC6822 employing a method based on evolved asymptotic
giant branch (AGB)
stars, known as long-period variable (LPV)
stars. We utilized a
dataset of 329 LPVs in JHK$_s$ bands to estimate the
star formation rate (SFR) over time and reconstructed the SFH of the
galaxy. In addition to obtaining the SFH assuming constant
metallicity values within the range of 0.0001 $<$ Z $<$ 0.012, we also adopted three distinct age-
metallicity relations (AMRs) to account for variations in the chemical content of the
galaxy throughout its lifetime. The SFH has been investigated in two regions. The bar region encloses a central area of 189 arcmin$^{2}$, and the outer region encircles a field beyond the bar region, extending to the radial distance of 3 kpc. In the bar region, we identified three episodes of
star formation peaking at $t \sim$ 4.7 Gyr (log $t = 9.67$), $t \sim$ 1.6 Gyr (log $t = 9.21$), and $t \sim$ 48 Myr (log $t = 7.63$), where $t$ is the look-back time. In the outer region, we found one episode of
star formation occurring at $t \sim$ 4.6 Gyr. The significant peak observed $\sim$ 4-5 Gyr ago further supports the hypothesis suggested by the previous research, indicating that NGC6822 passed through the virial radius of the Milky Way in the past.
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All authors Fatemeh Khatamsaz, Mahdi Abdollahi, Atefeh Javadi, Hamidreza Mahani, Jacco Th. van Loon, Hedieh Abdollahi, Sepideh Ghaziasgar
General Relativity and Quantum Cosmology
Relic Neutrinos Probing Small Scale Primordial Non-Gaussianity
Suraj Gavhale, Shin'ichi Nojiri, Sergei D. Odintsov et al. (+1 more)
Relic
neutrinos retain a record of electromagnetic
entropy production after
neutrino decoupling, probing
primordial modes erased from the primary CMB. We derive the cubic
photon number source from acoustic damping and its leading folded sensitive bispectrum window, with
neutrino decoupling, thermalization, and acoustic coherence combined in a single response kernel. For excited initial states, this kernel filters the physical folded profile and yields a sharpness dependent transmission condition, directly connecting small scale
primordial non-Gaussianity to relic
neutrino capture rates.
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All authors Suraj Gavhale, Shin'ichi Nojiri, Sergei D. Odintsov, Oem Trivedi
High Energy Physics (Theory)
Three-loop anomalous dimensions of leading-twist operators in the Gross-Neveu-Yukawa model
Mrigankamauli Chakraborty and Leonid A. Shumilov
We compute the anomalous dimensions of the leading-twist operators at three-loop level in the $\overline{\text{MS}}$ scheme in the Gross-Neveu-Yukawa model. Calculations are done for a number of low-
spin operators using computer
algebra systems, and the analytical form is reconstructed by solving a set of Diophantine equations. Calculations are optimized using the emergent supersymmetry of the corresponding generalized theory. For the obtained results, we perform a comprehensive analysis at the critical point, including a comparison with the $1/N$ expansion, a check of the generalized Gribov-Lipatov reciprocity, and an analysis of the behavior next to the rightmost singularity. The latter allows us to extract the values of Regge intercepts for all the leading-twist trajectories in the form of an $\epsilon$ expansion.
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Astrophysics of Galaxies
Improving Lens Modelling from Ground-Based Imaging with Deconvolution
Eric Paic, Kenneth C. Wong, Anupreeta More et al. (+1 more)
Accurate and precise mass modelling of strong
lensing systems is essential for extracting insights into cosmology,
galaxy environments, and the nature of dark matter. The Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP), which has mapped $\sim$1000 square degrees of the sky, discovered over 1000 definite or probable
galaxy-scale gravitational lens candidates. As the resolution of ground-based imaging poses challenges for accurate lens modelling, high-resolution imaging is traditionally sought after for detailed analyses of these systems. In this work, we instead propose applying the STARRED
algorithm, which leverages starlet wavelet regularisation, as a preprocessing step before lens modelling to maximise the scientific output of the large HSC-SSP sample. We test this approach on seven HSC-like mock
lensing systems with different
lensing configurations. Our results show that the resolution boost from $\sim$0.6" to $\sim$0.15" enables improved accuracy and sub-3% precision measurements of key
lensing parameters such as the Einstein radius and the mass axis ratio for ground-based images. These results pave the way for accurate measurements of key strong
lensing quantities from a large sample of ground-based observations.
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All authors Eric Paic, Kenneth C. Wong, Anupreeta More, Anton T. Jaelani