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Physics

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Monday 10 August

Materials Science

Spatially resolved elastic strain and lattice rotation at threading dislocations in HgCdTe/CdZnTe epilayers by dark-field X-ray microscopy

C. Yildirim, A. Benhadjira, P. Ballet et al. (+5 more)

Threading dislocations (TDs) propagating from a Cd$_{1-y}$Zn$_{y}$Te (CZT) substrate into a liquid-phase-epitaxy Hg$_{1-x}$Cd$_{x}$Te (MCT) epilayer set the minority-carrier lifetime and dark-current floor of mid-wave infrared focal-plane arrays, yet at device-grade densities their local strain fields have been accessible only through topography, which conflates lattice tilt and elastic strain. We apply dark-field X-ray microscopy in reflection geometry to a \SI{7}{\micro\metre}-thick (111) MCT/CZT epilayer. Shallow Bragg angle and absorption makes the signal layer dominated while the numerical aperture of the objective keeps the layer and substrate rocking curves convolved, so weak-beam images on either side of the rocking curve and their difference image the correlated defects in a single frame: dot-like substrate TDs and the elongated, in-plane island features they nucleate in the layer. Kernel average misorientation resolves each TD as a \SI{7}{\micro\metre} signature, the layer thickness, alongside axial strain lobes of $\pm(4$ to $5)\times10^{-5}$.
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All authors C. Yildirim, A. Benhadjira, P. Ballet, T. N. Tran Caliste, J. Baruchel, C. Detlefs, D. Brellier, M. P. Kabukcuoglu

Instrumentation and Methods for Astrophysics

NASA ASTRA Initiative White Paper: Space-Based Mission for Ultrahigh Energy Particles

Mauricio Bustamante, Johannes Eser, Ke Fang et al. (+9 more)

Ultra-high-energy cosmic rays ($E_{\rm CR} \gtrsim 1$ EeV) are the highest-energy particles known, signaling extreme particle processes at work in the universe. However, many aspects of their nature remain largely unknown, even after more than a century of study. Very-high-energy ($E_\nu \gtrsim 1$ PeV neutrinos associated with cosmic-ray interactions, both during the acceleration process and propagation, would provide new insight into these extreme particles, as we have seen at lower energies with the dawn of TeV neutrino astronomy. Nevertheless, only a handful of such neutrinos have been observed thus far. A space-based observatory dedicated to studying cosmic rays, neutrinos, and photons would provide an unprecedented platform for observations of these extreme-energy messengers.
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All authors Mauricio Bustamante, Johannes Eser, Ke Fang, Claire Guépin, John Krizmanic, Eric Mayotte, Keith McBride, Kohta Murase, Mary Hall Reno, Frank Schroeder, Tonia M. Venters, Stephanie Wissel

Quantum Physics

An upper bound for the purity of absolutely positive partial transpose states

Anh T. Tran

A quantum state is called absolutely separable (resp. absolutely positive partial transpose (APPT)) if it remains separable (resp. positive partial transpose (PPT)) under any global unitary transformation. It is known that the set of all absolutely separable states is a subset of the set of all APPT states. Moreover, these two sets are identical for qubit-qudit systems. In this note, we give an upper bound for the purity of APPT bipartite states (and therefore for the purity of absolutely separable bipartite states). For qubit-qudit systems, this upper bound becomes the maximum purity of APPT (and absolutely separable) states.
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Nuclear Experiment

Alpha Particle Induced Collision Cascade Fusion

Sandeep Puri, Noah D'Amico, Andrew Gillespie et al. (+4 more)

We report experimental and computational investigations of a collision-cascade mechanism to induce deuterium-deuterium (D-D) fusion. Evidence of neutron production was observed from a pressurized deuterium target exposed to energetic alpha particles emitted by a $^{210}\text{Po}$ source. A 5-mCi $^{210}\text{Po}$ alpha source was placed within a chamber containing pressurized deuterium gas, and neutron emission was monitored for 18 h using two Mirion SN-S $^{3}\text{He}$ neutron detectors. Alpha particles incident on pressurized deuterium gas produced an average excess of $\sim$74 neutrons after background subtraction, corresponding to a fusion neutron rate of $\sim$2.24 n/s. With LiD in the pressurized deuterium, the average excess increased to 268 neutrons, corresponding to 8.1 n/s. Since D-D fusion branches into two equally likely pathways, these correspond to a fusion rate near 4.5 and 16.2 fusions per second, respectively. MCNP simulations incorporating experimental geometry, source activity, and detector configuration predicted neutron yields within 5.4% of the measured values and reproduced the detector response within experimental uncertainty. The tight agreement between measured and simulated neutron counts suggests that energetic alpha-particle interactions within the deuterium may contribute to measurable D-D fusion reactions through the D(d,n)$^{3}\text{He}$ channel.
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All authors Sandeep Puri, Noah D'Amico, Andrew Gillespie, Ian Jones, Cuikun Lin, Bo Zhao, R. V. Duncan

Quantum Physics

Quantum Information Flow under String-Diagram Rewriting

Yi-Yu Lin and Chen-Ye Li

We revisit the notion of “quantum information flow” introduced in Bob Coecke's early work and seek to give it an explicit string-diagrammatic formalization. Given a semantics preserving string-diagram rewriting sequence, we first distinguish apparent through-paths, which depend on the current graphical presentation, from genuine through paths, which can be compatibly inherited through successive rewrites to a terminal decoupled bare wire factor. We then formally define a “Coecke flow line” in terms of this compatible inheritance relation. In particular, we use the ZX calculus, i.e., the ZX string diagram rewriting system, to illustrate the resulting formalism. In the physical setting of quantum protocols, a Coecke flow can be interpreted as a constrained, quasi-local, line-like presentation of a target bare wire morphism factor within the protocol string diagram.
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Materials Science

Polar-vortex-driven interfacial strain coupling in PbTiO3/SrRuO3 Heterostructures

S. A. Raza, V. A. Stoica, H. Zheng et al. (+7 more)

Interfacial coupling in oxide heterostructures is a central problem in condensed-matter physics, as it typically emerges at the atomic scale through local interactions mediated by lattice polarization and strain. In this work, we investigate nanoscale polar-supertexture-driven interfacial strain coupling in (PbTiO3)16/(SrRuO3)9/(PbTiO3)16 heterostructures grown on DyScO3(110) substrates. Under appropriate epitaxial strain conditions, the PbTiO3 layers form polar vortex superstructures with a periodicity of approximately 10 nm. We demonstrate that the resulting in-plane nanoscale strain modulation propagates into the SrRuO3 layer. Using element-specific resonant X-ray reflectivity, we probe the nanoscale strain modulations of the strontium and ruthenium sublattices at the interface, revealing strong interfacial strain coupling between the ferroelectric and ferromagnetic layers. These findings provide new insights into engineering nanoscale magnetic modulations through interfacial strain and polarization control.
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All authors S. A. Raza, V. A. Stoica, H. Zheng, H. G. Lee, A. Ross, U. Saha, L. Q. Chen, L. W. Martin, V. Gopalan, J. W. Freeland

High Energy Physics (Phenomenology)

Leptogenesis in Brane-modified cosmology: Signatures in primordial gravitational waves

Amit Dutta Banik and Arnab Paul

We investigate the implications of brane-inspired modifications of the evolutionary history of the early universe on the process of baryogenesis via leptogenesis. A modified cosmic history alters the evolution of the Boltzmann equations governing lepton asymmetry, providing the possibility of successful leptogenesis in regions of the parameter space inaccessible in the standard cosmological scenario. Furthermore, a modified cosmic history also alters the shape of an otherwise scale-invariant spectral energy density (SED) of primary gravitational waves (PGWs) produced during inflation. This establishes a novel yet indirect probe of high scale leptogenesis scenarios through the observation of the SED of PGWs via future observations. We consider two scenarios in this work with single and multiple epochs of stiff equation of state(s) after inflation and before the epoch of radiation domination. We identify the parameter space where successful leptogenesis is possible, along with the possible observability of the PGWs, hence providing an indirect window into this leptogenesis scenario through PGWs.
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Astrophysics of Galaxies

An emerging baryon cycle in a galaxy 500 million years after the Big Bang

Shengzhe Wang, Xin Wang, Hang Zhou et al. (+17 more)

The emergence of stellar feedback as a regulator of galaxy growth marks a fundamental transition in cosmic history. At early times, rapid gas accretion and collapse may induce intense star formation before feedback becomes effective, producing feedback-free starbursts. When and how such bursts subsequently develop into self-regulated baryon cycles remain observationally unknown. Here we show that Gz9p3, a merging galaxy at $z=9.311$, is caught in this transition only 500 million years after the Big Bang. Deep JWST spectroscopy reveals a substantial neutral-gas reservoir along its merger-driven tidal structure and a multiphase outflow. Fine-structure absorption provides the first direct measurement of the electron density of the cool outflowing gas at high redshift ($\approx\,17\,{\rm cm^{-3}}$), yielding a mass-loading factor among the highest yet measured for galaxies of comparable stellar mass. The emergence of such efficient feedback after an intense burst is consistent with the delayed onset of feedback expected in feedback-free starburst models. The cool outflowing gas is unlikely to escape the host halo, implying that much of this metal-enriched material may remain available for future recycling through the circumgalactic medium. Gz9p3 therefore provides an early view of a baryon cycle being established through the interplay of merger-driven gas redistribution, bursty star formation and stellar feedback, suggesting that feedback-regulated recycling was already shaping galaxy growth during the epoch of reionization.
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All authors Shengzhe Wang, Xin Wang, Hang Zhou, Zhijie Qu, Zhaozhou Li, Yuxuan Pang, Qianqiao Zhou, Shouyi Wang, Yangyao Chen, Yuguang Chen, Karl Glazebrook, Glenn G. Kacprzak, Nicha Leethochawalit, Houjun Mo, Themiya Nanayakkara, Huiyuan Wang, Weida Hu, Xunda Sun, Chao-Wei Tsai, Hu Zhan

General Relativity and Quantum Cosmology

Probing ultralight bosons with LISA observations of spinning black hole mergers and follow-up searches of merger remnants

Ifigeneia Giannakoudi, Maxence Corman and William E. East

Ultralight bosons can trigger superradiant instabilities around rotating black holes, extracting angular momentum and leading in some cases to observable gravitational signatures. When the associated spin-down timescale is shorter than the black hole lifetimes and the spin-up timescales due to, e.g. accretion, this process imposes an upper limit on black hole spins. In addition, the formation and subsequent dissipation of boson clouds generates quasi-continuous gravitational wave emission. In this work, we explore the prospects for constraining and detecting ultralight bosons with observations of massive black hole binary mergers with the space-based LISA observatory. We consider two complementary approaches: measurements of black hole spins from merging binaries and follow-up gravitational wave searches targeting massive black hole binary merger remnants. We consider three population models for massive black holes, based on either heavy or light seeds, and forecast the exclusion and detection probabilities for both scalar and vector bosons. We find that black hole spin measurements can constrain scalar masses in the range $[5\times10^{-18},10^{-14}]$ eV and vector masses in the range $[6\times10^{-19},2\times10^{-14}]$ eV, with the exact range depending on the model. In contrast, restricting to vector bosons, follow-up gravitational wave searches are sensitive to a narrower vector boson mass range of $\sim[3\times10^{-17},3\times10^{-15}]$ eV, with the specific values again depending on the model. If a vector boson with a mass in the range $[10^{-16},2\times10^{-15}]$ eV existed, the probability of having an event that the follow-up searches would be sensitive to ranges from very small to near unity depending on the astrophysical model.
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Quantum Physics

From Barren Plateaus to SPSA Optimization in Variational Quantum Eigensolvers

Zhen Qin

The barren plateau (BP) phenomenon poses a fundamental challenge to the trainability of variational quantum eigensolvers (VQEs) by causing exponentially vanishing gradients as the system size increases. While extensive studies have investigated the geometric origins of BP, its impact on the optimization dynamics and complexity of practical algorithms under finite-shot measurements has received comparatively less attention. In this paper, we develop a theoretical framework that characterizes how the BP affects the optimization dynamics of the Simultaneous Perturbation Stochastic Approximation (SPSA) algorithm and quantifies the resulting iteration complexity and measurement budget. We derive non-asymptotic bias and variance bounds for the SPSA gradient estimator, introduce a signal-to-noise ratio (SNR) defined as the ratio of the gradient energy to the mean squared error of the estimator, and establish convergence guarantees for SPSA under finite-shot measurements. Our results show that, under the proposed parameter schedules, the number of iterations sufficient to guarantee a fixed relative first-order stationarity level scales polynomially with the inverse of the intrinsic gradient energy. Consequently, when this energy decays exponentially under BP, the resulting guaranteed iteration complexity and total measurement budget both grow exponentially with the number of qubits.
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Chaotic Dynamics

Integral of an alpha unpredictable function

M.U. Akhmet and N. Tilessov

The present paper is devoted to the study of integral properties of alpha unpredictable functions. The problem of invariance of recurrence under integration is one of the most challenging and interesting in the theory of functions. Let us start with periodicity. Next, the problem was solved for quasiperiodic, almost periodic, and Poisson stable functions. All of the problems were subjected to the condition of bounded integrals. The alpha-unpredictable functions are the endpoint in the row of recurrent functions. The class is the cross-border point from regularity to chaos in the dynamics presented through the elements of the row. In the present research, we finalized the proof that any theoretical functional recurrence is invariant with respect to integration, provided the result is bounded.
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Computational Physics

Autonomous Lindblad Realizability of Nonunitary Linear Dynamics with a Carleman Lattice Boltzmann Application

Muhammad Idrees Khan

Carleman lifting converts nonlinear polynomial dynamics into finite linear systems, but the resulting truncations are generally nonunitary and need not correspond to physical quantum evolution. We prove that a finite linear endpoint admits an autonomous Gorini–Kossakowski–Sudarshan–Lindblad (GKSL) realization on vacuum coherences if and only if it is invertible and power bounded. The construction is explicit and realizes the nonunitary map directly as open-system dynamics, with no endpoint postselection and with one encoding and one decoding over repeated timesteps. We apply the result to the complete D2Q9 multiple-relaxation-time lattice Boltzmann (LB) timestep by compiling collision and periodic streaming into a single Carleman endpoint. The resulting GKSL evolution reproduces the classical Carleman trajectory over multiple timesteps, while the remaining discrepancy from nonlinear LB dynamics is the expected Carleman truncation error. The result establishes a general criterion for autonomous open-quantum realization of finite nonunitary dynamics, with Carleman–LB dynamics as a concrete example.
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Instrumentation and Methods for Astrophysics

Unified matched-filter and excess-power pipeline for gravitational-wave detector characterization

Zach Yarbrough, Olivia Godwin, Derek Davis et al. (+1 more)

We present sgnax, an open-source pipeline for gravitational-wave detector characterization that produces matched-filter and excess-power transient triggers within a single streaming dataflow graph. Built on the Stream Graph Navigator (sgn) framework, sgnax combines the multi-rate sine-Gaussian matched filtering of snax and the multi-resolution Q-transform of omicron in a Python-native package with shared configuration and output formats. Strain and auxiliary channels share data ingestion and whitening, reducing per-channel processing costs by a factor of 2.8 from one to 32 channels for the Q-transform. A full day of 16 kHz strain is processed in 14 minutes; four processes sharing an NVIDIA V100 analyze 792 auxiliary channels at 1.11 times real-time throughput. The same configuration supports offline and online operation through frame caches, shared memory, and the arrakis distribution service. Matched-filter triggers have approximately five seconds of end-to-end latency, while Q-transform triggers are available within tens of seconds. Injection studies recover 99.4% of recoverable sine-Gaussian signals and show broadband burst recovery consistent with established generators. On 24 hours of LIGO strain, sgnax agrees with production omicron to 0.1% in total trigger count, with per-trigger signal-to-noise ratios agreeing at the percent level across frequency bands. Auxiliary-channel comparisons recover 80% of the snax loud-feature population per time bin. The validation also reveals a multiband amplitude error in production snax that inflates reported signal-to-noise ratios below 25.6 Hz by factors of sqrt(2) to 2.
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All authors Zach Yarbrough, Olivia Godwin, Derek Davis, Gabriela González

High Energy Physics (Theory)

Closed-form thermal threshold functions for the proper-time renormalisation group

Daniele Rizzo

We derive closed-form expressions for the thermal threshold functions of the finite-temperature proper-time renormalisation group (PTRG): until now these have been evaluated numerically, Matsubara mode by Matsubara mode. For the standard one-parameter regulator family, Poisson resummation of the Matsubara sum yields a rapidly convergent winding-number series of modified Bessel functions, and a single algebraic identity reduces every higher threshold function to this same closed form at a shifted kernel parameter. The sharp proper-time regulator, recovered as the exact $m\to\infty$ endpoint of the family with a controlled $O(1/m)$ approach, factorises into a field-dependent and a purely thermal piece. Built on them, the local potential approximation (LPA) and its refinement to a running anomalous dimension (LPA$'$) for the $O(N)$-symmetric theory reduce to established results, all cross-checked against the exact Wetterich equation with the optimised regulator. Two findings go beyond reduction. First, the known zero-temperature anomalous-dimension construction is extended here to finite temperature. Second, because the closed form holds for any real regulator parameter, the refined truncation's fixed point can for the first time be tracked as a continuous function of the regulator, rather than at a handful of isolated points, and is found to vary smoothly and remain bounded, with no special or pathological point anywhere on the line.
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High Energy Physics (Theory)

Thermal Origin of Black Hole Quasinormal Modes

D. Giataganas, G.F. Giudice, A. Kehagias et al. (+2 more)

When a black hole rings after a merger, it emits gravitational waves at characteristic frequencies known as quasinormal modes (QNMs). In the eikonal limit, these modes are governed by the unstable circular light orbits that form the photon ring. In this work, we demonstrate that the ringing of a black hole has a precise thermal interpretation. A probe string propagating in the near-ring geometry acquires an induced Rindler horizon on its worldsheet, with a temperature set by the Lyapunov exponent of the photon ring. Out of this structure, the black hole QNMs emerge as thermal excitations, so that the characteristic ringing of a black hole is the retarded response of a thermal system living on the photon ring. We explicitly derive the QNM spectrum from two complementary perspectives: microscopically, via unstable transverse worldsheet fluctuations, and macroscopically, through the pole structure of the causal response function of an open thermal quantum system.
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All authors D. Giataganas, G.F. Giudice, A. Kehagias, F. Quevedo, A. Riotto

Instrumentation and Methods for Astrophysics

Quasi-automatic software support for Gaia ground based optical tracking

S. Bouquillon, C. Barache, T. Carlucci et al. (+6 more)

The ESA Gaia satellite mission will create a catalog of 1 billion stars with unprecedented astrometric precision. To achieve its aim in terms of astrometric precision, a ground based optical tracking campaign (GBOT) of the satellite itself is necessary during the five years of the mission. We present an overview of the GBOT project as a whole in another contribution (Altmann et al. in SPIE category "observatory operations"). The present paper will focus more specifically on the software solutions developed by the GBOT group.
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All authors S. Bouquillon, C. Barache, T. Carlucci, F. Taris, M. Altmann, A. H. Andrei, R. Smart, I. A. Steele, S. G. Els

Quantum Physics

Security of quantum key distribution with passive basis choice and detection-efficiency mismatch for a realistic satellite setup

Egor Ivchenko, Aleksandr Khmelev, Vladimir Kurochkin et al. (+1 more)

Detection efficiency mismatch is a common problem in realistic quantum key distribution (QKD) systems. Existing security proofs for passive basis choice provide a nonzero secret key rate for small detection efficiency mismatches only. Unfortunately, in realistic setups, the detection efficiency mismatch can be significant. Here, we present a different approach for estimating the secret key rate for the BB84 protocol with passive basis choice and a detection efficiency mismatch between four threshold detectors, where the mismatch is not assumed to be small. We also adapt the decoy-state method for this case. The suggested approach is used to estimate the secret key rate in a QKD experiment between the Micius satellite and the Zvenigorod ground station.
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All authors Egor Ivchenko, Aleksandr Khmelev, Vladimir Kurochkin, Anton Trushechkin

Materials Science

Predictive Simulation of Interphases on Li Metal Surface

Xinyu Li, Jingxuan Ding, Daniel C. Hannah et al. (+3 more)

Interphases remain the least understood components in advanced batteries. Although their properties dictate whether a new battery chemistry could perform as designed, there has never been a reliable way to predict what an interphase could arise from a new electrolyte system due to the absence of atomistic level knowledge about interphasial formation process. In this work, we attempt to develop a simulation method that can universally predict interphasial chemistries formed on Li metal surface, so that the electrolyte engineering would no longer need lengthy Edisonian approaches. By combining a transferable universal polarizable force field and a universal machine learning force field, we simulate interphasial chemistry across chemically diverse electrolyte formulations, and successfully replicate the experimental observation that fluorinated solvents promote the formation of LiF-rich interphases, whereas interphases of more organic origin arise from conventional carbonate-based electrolytes. By directly capturing these spontaneous interfacial reactions behind these interphasial chemistries, our simulations establish molecular-level relationships between electrolyte chemistry, salt concentration, decomposition pathways, and SEI properties, and opens a route toward universal and high-throughput predictive simulation of interphases that is the foundation for AI-driven electrolyte discoveries.
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All authors Xinyu Li, Jingxuan Ding, Daniel C. Hannah, Yumin Zhang, Qichao Hu, Kang Xu

Mathematical Physics · Cross-listed from math.AT

Preferential Attachment as a Simpliciality-Enforcing Mechanism in Hypergraphs

Jason LaRuez and Brendan Rooney

Higher-order networks, represented as hypergraphs, enable direct modeling of multi-body interactions of arbitrary size. Hypergraph representations of real-world systems have been observed to exhibit high simpliciality — the tendency for subsets of hyperedges to also appear as hyperedges — yet the generative mechanisms responsible for this structure are poorly understood. We introduce a generalized preferential attachment hypergraph model in which both hyperedge size $Y_t$ and the number of new nodes per step $X_t$ are drawn from arbitrary distributions, and derive analytically, using a mean-field approximate master equation approach, that the stationary hyperdegree distribution follows a power law whose exponent depends only on the ratio $p = E[X_t]/E[Y_t]$, independent of the shapes of the underlying distributions. Crucially, both $X_t$ and $Y_t$ can be estimated directly from any timestamped hypergraph dataset via a backward-stepping procedure, enabling the model to be fit without parametric assumptions. Applying a nonlinear extension of the model to eight real-world hypergraph datasets, we find that the simplicial fraction increases monotonically with the strength of preferential attachment up to the gelation transition at $\alpha > 1$, establishing preferential attachment as a simpliciality-enforcing mechanism.
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Superconductivity

Superconductivity, pseudogap and marginal Fermi liquid in a relative-momentum-local theory

Jian-Jian Miao

Cuprate superconductors host \(d\)-wave superconductivity (SC), a pseudogap (PG) with Fermi arcs and a strange metal (SM) with incoherent excitations and temperature-linear resistivity. These regimes emerge from the same doped Mott system but are usually described separately. Here a relative-momentum-local (RML) theory is constructed, with the exact spin-singlet Cooper representation of antiferromagnetic superexchange in the \(t\)-\(J\) model serving as a common thread. Pair correlations organize the low-energy behaviour of this Cooper channel into phase-coherent static SC, phase-incoherent quasi-static PG and phase-incoherent dynamic SM. A static RML prescription yields an exactly solvable PG Hamiltonian with nodal electron poles, antinodal gaps, resolution-broadened Fermi arcs and gapless charge-\(2e\) Cooper surfaces. A Cooper-surface Lifshitz transition generates logarithmic enhancements in the specific-heat coefficient and charge response without a spin singularity. The particle-particle continuum at finite centre-of-mass momentum produces Ohmic damping, while a dynamic RML prescription yields a one-loop self-energy with marginal-Fermi-liquid scaling. Spectral-weight transfer in the physical pair spectrum diagnoses the PG–SM crossover, whereas nonzero phase stiffness and global phase coherence identify SC. The RML theory relates single-particle, pair-sensitive and thermodynamic probes to three infrared organizations of one Cooper channel. A decisive experimental signature would be zero-energy Cooper-surface ridges in two-electron angle-resolved photoemission spectroscopy (2e-ARPES).
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General Relativity and Quantum Cosmology

Adiabatic Perturbations in GW170817-Compatible Einstein-Gauss-Bonnet Inflation

S.D. Odintsov and V.K. Oikonomou

We study the adiabaticity of the cosmological perturbations in the context of inflationary Einstein-Gauss-Bonnet theories. We focus on viable inflationary Einstein-Gauss-Bonnet theories which are compatible with the current Cosmic Microwave Background radiation experiments and also are compatible with the GW170817 observations. We derive the effects of the adiabaticity requirement on the Einstein-Gauss-Bonnet physical parameters and we show that the sound speed of the scalar perturbations and the propagation speed of the tensor perturbations are constrained. We consider two classes of inflationary viable and GW170817-compatible theories, and in the first class the adiabaticity is not violated during inflation, while in the second class the adiabaticity is violated only at the end of inflation. We discuss the effects of the adiabaticity violation in the second class of models. From our analysis, it seems that only one class of viable EGB inflationary theories, which is also compatible with the GW170817 event, is free from adiabaticity pathologies.
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Instrumentation and Methods for Astrophysics

Pulsar Timing Array Sensitivity to Anisotropy: Empirical Sensitivity Curves, Scaling Relations, and the Multi-Resolution Pixel Basis

Taha T. Moursy, Nihan S. Pol, Gabriella Agazie et al. (+115 more)

We quantify pulsar timing array (PTA) sensitivity to anisotropy in the gravitational wave background using the cross-correlation based Fisher information matrix in the pixel and spherical harmonic bases. We use a set of simulations to empirically determine scaling relations of a PTA's sensitivity to anisotropy with the number of pulsars $N_\mathrm{psr}$ in the array, the error $\delta t$ on the times of arrival, the frequency $f_\mathrm{GW}$ of the gravitational waves, and the angular scale $\Delta\Omega$ of the anisotropy. The sensitivity scales approximately as $N_\mathrm{psr}^{0.8}$, $\delta t^{-0.08}$, and $\Delta\Omega^{1.6}-\Delta\Omega^{2.1}$ (depending on the ranges of $\ell$ and $m$ under consideration). In addition, we use realistic simulations to project the NANOGrav PTA sensitivity to a 30-year baseline and quantify the growth in sensitivity at several timeslices. Except at the lowest frequencies, we find negligible effect on sensitivity through increasing the observation duration only. Finally, we introduce a multi-resolution pixel basis motivated by the large dependence of the sensitivity on sky location, and demonstrate the operation of the basis through a set of injections and recoveries.
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All authors Taha T. Moursy, Nihan S. Pol, Gabriella Agazie, Nikita Agarwal, Akash Anumarlapudi, Anne M. Archibald, Zaven Arzoumanian, Anjana Ashok, Jeremy G. Baier, Paul T. Baker, Bence Bécsy, Laura Blecha, Adam Brazier, Paul R. Brook, Sarah Burke-Spolaor, Rand Burnette, Robin Case, J. Andrew Casey-Clyde, Maria Charisi, Shami Chatterjee, Tyler Cohen, James M. Cordes, Neil J. Cornish, Fronefield Crawford, H. Thankful Cromartie, Kathryn Crowter, Megan E. DeCesar, Paul B. Demorest, Heling Deng, Lankeswar Dey, Timothy Dolch, Graham M. Doskoch, Elizabeth C. Ferrara, William Fiore, Emmanuel Fonseca, Gabriel E. Freedman, Emiko C. Gardiner, Nate Garver-Daniels, Peter A. Gentile, Kyle A. Gersbach, Joseph Glaser, Deborah C. Good, Kayhan Gültekin, Aiden Gundersen, C. J. Harris, Jeffrey S. Hazboun, Ross J. Jennings, Aaron D. Johnson, Megan L. Jones, David L. Kaplan, Anala K. Sreekumar, Luke Zoltan Kelley, Matthew Kerr, Joey S. Key, Nima Laal, Michael T. Lam, William G. Lamb, Bjorn Larsen, T. Joseph W. Lazio, Natalia Lewandowska, Tingting Liu, Duncan R. Lorimer, Jing Luo, Ryan S. Lynch, Chung-Pei Ma, Dustin R. Madison, Ashley Martsen, Cayenne Matt, Alexander McEwen, James W. McKee, Maura A. McLaughlin, Natasha McMann, Bradley W. Meyers, Patrick M. Meyers, Matthew T. Miles, Chiara M. F. Mingarelli, Andrea Mitridate, Cherry Ng, David J. Nice, Shania A. Nichols, Stella Koch Ocker, Daniel J. Oliver, Ken D. Olum, Timothy T. Pennucci, Benetge B. P. Perera, Polina Petrov, Henri A. Radovan, Scott M. Ransom, Paul S. Ray, Joseph D. Romano, Jessie C. Runnoe, Alexander Saffer, Shashwat C. Sardesai, Ann Schmiedekamp, Carl Schmiedekamp, Kai Schmitz, Levi Schult, Brent J. Shapiro-Albert, Xavier Siemens, Joseph Simon, Sophia V. Sosa Fiscella, Ingrid H. Stairs, Daniel R. Stinebring, Kevin Stovall, Abhimanyu Susobhanan, Joseph K. Swiggum, Jacob Taylor, Stephen R. Taylor, Mercedes S. Thompson, Jacob E. Turner, Michele Vallisneri, Rutger van Haasteren, Sarah J. Vigeland, Haley M. Wahl, Kevin P. Wilson, Caitlin A. Witt, David Wright, Olivia Young

High Energy Physics (Theory)

Schwinger-Keldysh effective field theory of type-B Goldstone: near-diagonal geometry and Berry term

Pei Zheng and Mei Huang

In this work, we formulate a finite temperature Schwinger-Keldysh effective field theory for type-B Goldstone modes based on geometric objects globally defined on the coset manifold. In particular, after taking the classical limit, we organize the required two time contour structure by a near-diagonal geometry in which the $r$-type field is interpreted as the physical Goldstone configuration and the $a$-type field is identified as corresponding tangent displacement. Within this geometric viewpoint, the Berry term essential for type-B Goldstones is obtained directly through the transgression of the Berry curvature. Moreover, we show that this exact Berry transgression is compatible with dynamical KMS condition. In order to construct the conservative, dissipative and noise sectors, we classify possible tensors globally defined on the coset manifold. Based on this framework, we discuss in detail two concrete model examples. The dispersion relations of the Goldstone modes and the associated two-point correlation functions are calculated in the presence of dissipation.
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Computational Physics · Cross-listed from q-bio.NC

Graph Analysis of Neuronal-Culture Connectivity Derived from a Reservoir-Computing Model

Ilya Auslender, Giorgio Letti, Yasaman Heydari et al. (+1 more)

Graph-theoretical analysis offers a principled framework for quantifying emergent dynamics in neuronal cultures. Here, we present an analytical pipeline for inferring network-level properties of in vitro cortical cultures from multichannel electrophysiological recordings. The approach builds on a recently proposed Reservoir Computing (RC) framework (Auslender et al., 2025), which enables direct extraction of an Intrinsic Connectivity Map (ICM) from neural activity. We interpret the ICM as an effective adjacency matrix and apply graph-theoretic centrality measures to quantify node- and edge-level contributions to the culture's collective dynamics. We systematically evaluate both local and global graph metrics and examine their relationships with experimentally measured activity features, including firing rates and network-level descriptors. To validate the inference procedure, we also simulate the experimental environment, enabling controlled benchmarking of the RC-derived connectivity against a known ground-truth adjacency matrix and assessment of model performance as a function of graph structure. Our results demonstrate statistically robust associations, of varying strength, between graph-theoretic measures and experimentally observed activity patterns. These findings additionally support the validity of the RC-based connectivity inference and establish a scalable, data-driven framework for functional network characterization in neuronal culture systems.
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All authors Ilya Auslender, Giorgio Letti, Yasaman Heydari, Lorenzo Pavesi

Mesoscale and Nanoscale Physics

Disorder-robust trivial Majorana-like states from smooth confinement in chiral superconducting nanowires

Eslam Ahmed, Jorge Cayao and Yukio Tanaka

Near-zero-energy states in Majorana nanowires can arise from topologically trivial mechanisms such as smooth spatial inhomogeneity and disorder, making zero-energy pinning alone insufficient evidence of bulk topology. Here we identify a real-space mechanism governing their robustness to symmetry-preserving disorder. For a chiral-symmetric Bogoliubov-de Gennes Hamiltonian, we decompose a low-energy state into two normalized components of opposite chirality and show that disorder-induced splitting is bounded by their spatial overlap. We demonstrate this result in a finite Rashba nanowire with smooth chemical potential and pairing profiles. Below the bulk topological transition, smooth confinement produces partially separated chiral components with exponentially small overlap, yielding globally trivial Majorana-like Andreev bound states that remain near zero energy even under strong scalar, nonmagnetic disorder. The chiral overlap therefore provides a direct diagnostic of the protection of low-energy states against local perturbations, independent of the bulk topological invariant.
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Mesoscale and Nanoscale Physics

Probing crystal-field modulations with magnetic adatoms on the incipient charge-density-wave superconductor $2H$-NbS$_2$

Werner M.J. van Weerdenburg, Margarete Huisinga, Constantin Flommersfeld et al. (+2 more)

The interplay between multiple quantum phases in layered materials may lead to incipient quantum behavior, where the material's ground state is close to a phase transition and sensitive to local disorder. The transition metal dichalcogenide material $2H$-NbS$_2$ exhibits incipient charge-density-wave behavior along with a well-developed superconducting state, creating a scenario where the local lattice instabilities play a crucial role. Here we present how an individual magnetic atom on $2H$-NbS$_2$ can be applied as a local sensor to reveal hidden crystal-field modulations. By manipulating the adatom across the surface with the tip of a scanning tunneling microscope, we measure variations in the Yu-Shiba-Rusinov (YSR) excitation spectra and map the local environment around an intrinsic point defect. We find that while the superconducting state is spatially uniform, the YSR excitation energy strongly depends on the position of the atom. We determine that the main contribution to this effect originates from variations in the local crystal-field environment. These results establish a new approach to investigate crystal-field modulations at the atomic scale and reveal how defects and lattice instabilities shape the atomic landscape of an incipient charge-density-wave material.
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All authors Werner M.J. van Weerdenburg, Margarete Huisinga, Constantin Flommersfeld, Lisa M. Rütten, Katharina J. Franke

Superconductivity

Revealing Hidden Unconventional Pairing through Nonreciprocal Transport

Wen-Bo Dai, Ming Gong, Xianxin Wu et al. (+2 more)

Identifying the pairing symmetry of Cooper pairs is a fundamental step toward understanding the microscopic mechanisms of unconventional superconductors. However, experimental identification remains a formidable challenge, particularly when unconventional pairing is obscured by a dominant $s$-wave component that masks its spectroscopic signatures. Here, we develop a symmetry-resolved framework to identify superconducting pairing symmetry through nonreciprocal conductance upon exchanging source and detector terminals in multiterminal devices. We show that nonreciprocal transport arises from symmetry-breaking components of the superconducting order parameter and exhibits a characteristic angular dependence that encodes the momentum-space structure of the pairing gap. In particular, time-reversal-breaking singlet pairing induces nonreciprocal charge transport, while spin-triplet pairing generates nonreciprocal spin responses, providing distinct transport fingerprints of the underlying order. We demonstrate this mechanism using representative models of iron-based and noncentrosymmetric superconductors and outline experimental protocols for multiterminal measurements. Our results advance the theoretical understanding of nonreciprocal transport in superconductors, and establish it as a symmetry-selective probe for identifying hidden unconventional pairing in a wide range of superconducting materials.
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All authors Wen-Bo Dai, Ming Gong, Xianxin Wu, Chui-Zhen Chen, X. C. Xie

Quantum Physics

Quantized Stabilizer-Rényi Boundary Response across Fermionic SPT Transitions

M. A. Rajabpour

Open boundaries host symmetry-protected Majorana modes, yet their imprint on the stabilizer Rényi entropy is obscured by a nonuniversal volume law. At Rényi index $\alpha=1/2$, we isolate a bulk-subtracted boundary response in free-fermion BDI chains using exact finite-open-chain relations, large-$L$ Pfaffian evaluations, and direct positive-weight checks. Across a mass inversion, this response approaches $|\Delta\omega|\ln 2$, where $\Delta\omega$ is the change in winding number. The response survives primitive bulk deformations, the tested local boundary perturbations, and broken bulk duality. Thus, for the families studied here, the boundary response counts the Majorana channels that change the fermionic SPT index.
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Chemical Physics

Decoding Transient X-ray Absorption Spectra of Acetylacetone With Multireference Algebraic Diagrammatic Construction Theory

Bennett W. Clark, Donna H. Odhiambo, Haden Dickerson et al. (+1 more)

Time-resolved X-ray absorption spectroscopy (TR-XAS) offers an element- and site-specific probe of coupled electronic and nuclear dynamics, but its interpretation requires methods that can treat multiconfigurational excited states across nonequilibrium nuclear ensembles. Here, we report time-resolved simulations of the acetylacetone (AcAc) transient X-ray absorption spectra by combining surface-hopping dynamics from complete active space second-order perturbation theory with multireference algebraic diagrammatic construction (MR-ADC). The simulated 20-200 fs spectra show a good agreement with experimental measurements and reveal that the TR-XAS response is governed by continuously evolving distributions of molecular geometries on the singlet potential energy surfaces (S2 and S1). In particular, absorption at 279.5-281.5 eV is enhanced for transient, nearly symmetric proton-sharing configurations, whereas the 284-286 eV profile reflects geometry-dependent C1s excitations modulated by proton transfer, bond alternation, and ring opening. For the long-time T_1 spectrum (7-10 ps), the principal features near 281.4 and 283.8 eV are assigned to central C 1s excitations into low-lying triplet pi-orbitals. Together, our simulations provide a more complete mechanistic picture of AcAc photorelaxation by directly linking ultrafast carbon K-edge signals to proton transfer, skeletal reorganization, internal conversion, and triplet formation.
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All authors Bennett W. Clark, Donna H. Odhiambo, Haden Dickerson, Alexander Yu. Sokolov

General Relativity and Quantum Cosmology

Formation of trapped surfaces for the spherically symmetric Einstein-Yang-Mills system with non-trivial incoming data

Nikolaos Athanasiou, Puskar Mondal and Shing-Tung Yau

We establish a trapped surface formation theorem for the spherically symmetric Einstein Yang Mills equations in a double-null gauge. The theorem concerns characteristic initial data posed on a pair of transversely intersecting null hypersurfaces and allows nontrivial incoming data. The proof extends the singular characteristic method of An and Lim for the Einstein Maxwell Charged Scalar Field System to the non-abelian Yang Mills setting, where the curvature coupling and gauge field nonlinearities introduce new structural difficulties. This paper constitutes the first part of a program toward weak cosmic censorship for the Einstein Yang Mills system.
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