Chemical Physics
Heteroatom Position Controls Ultrafast Photodynamics of Oxazole and Isoxazole
Briony Downes-Ward, Paul Javed, Huynh V. S. Lam et al. (+27 more)
The ultrafast photochemistry of heterocyclic compounds is central to photobiology and materials chemistry, yet direct experimental observation of their structural dynamics remains rare. Here we present the first real-time structural characterization of photoinduced ring opening and subsequent fragmentation in the isomeric pair oxazole and isoxazole using MeV ultrafast electron diffraction (UED), complemented by non-adiabatic molecular dynamics simulations. Upon photoexcitation at 200 nm, both isomers undergo ring opening followed by fragmentation into various products, but with strikingly different dynamics governed by heteroatom positioning. Trajectory Surface Hopping simulations reproduce the experimental diffraction signatures, which are surprisingly similar for both isomers, and reveal distinct mechanistic pathways for the two isomers. For isoxazole, all trajectories exclusively undergo N-O bond cleavage within 40 fs, followed by sequential fragmentation into HCN + ketene and HCO + vinyl nitrene channels on the hundreds-of-femtoseconds timescale. Oxazole, by contrast, shows significantly slower ring opening (290 fs) with only 85% efficiency, proceeding primarily through O-C cleavage and accessing a richer landscape of intermediates including nitrile ylide and O-pyramidalized structures. Simulated diffraction patterns derived from trajectory ensembles, convolved with the experimental instrument response function, are in agreement with the branching ratios observed by UED. This synergy between UED and trajectory surface hopping provides an atomistic picture of how the simple interchange of heteroatom connectivity in structural isomers fundamentally reshapes excited-state potential surfaces, conical intersection accessibility, and photochemical outcome.
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All authors Briony Downes-Ward, Paul Javed, Huynh V. S. Lam, Sajib K. Saha, Surjendu Bhattacharyya, Martin Centurion, Xinxin Cheng, R. Joel England, Casey Foley, Smita Ganguly, Patrick L. Kramer, Jinxin Lang, Randy Lemons, Ming-Fu Lin, Yusong Liu, Tu T. Nguyen, Joao Pedro Figueira Nunes, Chatura Perera, Alexander H. Reid, Ethan Ross, Artem Rudenko, Xiaozhe Shen, John Searles, Anbu Selvam Venkatachalam, Enliang Wang, Stephen P. Weathersby, Vinod Kumarappan, Arthur G. Suits, Christine Aikens, Daniel Rolles
Disordered Systems and Neural Networks
Connecting finite-size scaling and renormalization-group flows in Anderson localization on random graphs
Ignacio García-Mata, Weitao Chen, John Martin et al. (+2 more)
We investigate the relation between two complementary descriptions of the Anderson transition on small-world random graphs: finite-size scaling of eigenfunction moments and renormalization-group (RG) flows of multifractal dimensions $D_q$. The RG flows recover the qualitative structure previously reported for the information dimension $D_1$, while their extension to other $D_q$ with smaller moment orders $q<1/2$ confirms the strongly multifractal nature of the localized phase characterized by a clear separation between multifractal and localized behaviors at strong disorder. On the other hand, we show that we can construct another beta function characterizing the flow of eigenfunction moments, whose collapse onto a single function across different disorder strengths provides a clear confirmation of single-parameter scaling property. These results indicate that the family of RG trajectories observed for the information dimension $D_1$ need not imply two-parameter scaling and Kosterlitz-Thouless like critical behavior. To characterize these properties, one should consider different observables, such as large $q>1/2$ and small $q<1/2$ eigenfunction moments, which are associated with distinct critical behaviors, in particular different critical exponents.
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All authors Ignacio García-Mata, Weitao Chen, John Martin, Bertrand Georgeot, Gabriel Lemarié
High Energy Physics (Theory)
Spread Complexity for Local Operator Quenches with Conserved Momentum
Ali Fatemiabhari
We study a family of locally excited states in two-dimensional conformal field theories in different setups, defined on the plane, on the cylinder, or at finite temperature. These states are constructed by assigning independent
chiral and anti-
chiral regulators to a local primary operator, leading to excitations carrying net momentum. We analytically calculate the first few Lanczos coefficients and the early time behaviour of the spread complexity associated with these states. Then, using numerical methods, we obtain the coefficients reaching larger Krylov indices and find the associated spread complexity for a longer range of time
evolution. We also compare the rate of change of the resulting spread complexity with the proposed
holographic dual quantity, related to the proper momentum of an infalling particle in the dual bulk, but we observe a mismatch.
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High Energy Physics (Theory)
Quantum vacuum interaction between semitransparent plates in a Pöschl-Teller background: an exact relative TGTG formula
Jose M. Muñoz-Castañeda, Inés Cavero-Peláez and Gonzalo Sancho-Garrido
We derive an exact background-dressed TGTG formula for the one-loop
quantum vacuum inter- action between two semitransparent Dirac-delta plates in the one-
soliton Pöchl-Teller background. The interaction is defined through a relative determinant in which the two isolated one-plate contributions are subtracted in the same background. As a result, the energy depends on the individual plate positions as well as on their separation. For repulsive plates, the normalizable zero mode does not induce an infrared divergence in the relative interaction energy. We also extend the construction to planar plates and analyze the corresponding position-dependent interaction forces.
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Atomic Physics
Systematic errors from scalar slowing-down models in transient SERF magnetometry
Marek Kopciuch, Harini Raghavan and Morgan W. Mitchell
Reduced Bloch models of
spin-exchange-relaxation-free (SERF) magnetometers commonly describe the coupled electron–
nuclear spin dynamics using a single
nuclear slowing-down factor. We show that this scalar description becomes inaccurate when the polarization magnitude changes appreciably. We derive an effective Bloch equation with separate longitudinal and transverse slowing-down factors, $q_\parallel(P)$ and $q_\perp(P)$, governing changes in polarization magnitude and direction. For $^{87}\mathrm{Rb}$ under representative SERF conditions and undergoing free-induction decay (FID), comparison with master-equation simulations shows that the dynamic scalar model produces a
magnetic-field estimation bias of up to $4.2\%$ at high initial polarization, while fixing the slowing-down factor at a reference value increases the error to $10.1\%$. Lowering the polarization suppresses this bias but also reduces the
magnetic-field information contained in the FID signal. We further show that the anisotropic response modifies noncollinear optical pumping and introduces an additional nonlinear contribution to the harmonic response under periodic driving. The resulting model retains the simplicity of a three-component Bloch description while improving the quantitative accuracy of transient and driven SERF magnetometry.
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Quantum Physics
Indefinite causal order with output-signalling instruments
Ricardo Silveira, Patrick Andriolo, Davide Poderini et al. (+2 more)
Quantum processes can exhibit indefinite causal order, allowing coherent superpositions of distinct orderings of events. Whether such processes generate genuinely noncausal statistics, however, depends not only on their global causal structure but also on the local operations available to the parties. Here, we restrict communication to the classical outcomes of local operations, yielding a causal polytope with new causal inequalities that can be violated using measure-and-reprepare,
entanglement-breaking instruments requiring no coherent transmission through the laboratories. Using a semidefinite-programming framework, we bound the achievable violations and reveal noncausal correlations that satisfy all conventional input-signalling inequalities, demonstrating that restricting the information available for communication can uncover forms of indefinite causal order inaccessible under less restrictive operational assumptions.
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All authors Ricardo Silveira, Patrick Andriolo, Davide Poderini, Dmitry Melnikov, Rafael Chaves
High Energy Physics (Phenomenology)
Prompting Particle Physics: Tokenized Multi-modal Foundation Models for Combinatorially Many Tasks
Nilotpal Kakati, Daniel Murnane, Baran Hashemi et al. (+5 more)
Reconstruction and simulation at a
collider experiment are long chains of specialised
algorithms, each tuned to a single step. We explore how one model can serve many of those steps at once, while still producing the intermediate objects (tracks, calorimeter
cells, clusters, particles and jets) that make the chain interpretable. To do so, we represent every object in a jet in a single shared
token vocabulary and train one model to map any subset of these modalities to any other. A task is then only a choice of which modalities to provide and which to request: particle flow, detector simulation and charged energy subtraction are all directions through the same set of weights. We train over all modality combinations, with a decoder emitting
tokens either autoregressively or in parallel. With tokenisation, both architectures train stably with little tuning. In evaluations, both models produce realistic reconstruction and simulation objects, with the autoregressive model particularly faithful to output from Geant4. The autoregressive model also outperforms a state-of-the-art particle flow
algorithm on many typical jet reconstruction metrics.
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All authors Nilotpal Kakati, Daniel Murnane, Baran Hashemi, Samuel Klein, Jeffrey Krupa, Eilam Gross, Lukas Heinrich, Michael Kagan
Soft Condensed Matter
Mechanical Clustering of Cells via the ExtraCellular Matrix
Ran Glinowiecki, Shahar Goren, Oren Tchaicheeyan et al. (+4 more)
Tissues are composites of living
cells and extracellular
matrix (ECM), that jointly determine their unique mechanical behavior. Here, we experimentally demonstrate that contractile
cells remodel the ECM by generating long-range bands of aligned and densified fibers that mechanically couple
cells into multicellular clusters. Using a finite-element model, we quantify the collective mechanical interactions mediated by these ECM bands for various volume fractions of
cells. The model incorporates contractile particles that mimic
cell-active forces within a nonlinear biological gel, inducing stiffening internally rather than through external loading. We find that even a small volume fraction of contractile particles (approximately 10%), much below what is expected for percolation of sphere contacts, leads to internal stiffening, mediated by the high-concentrated stress bands between
cells and is strongly dependent on the nonlinear mechanical response of the ECM. Percolation analysis of the band network reveals sharp transitions at a critical particle volume fraction, that aligns with the onset of internal stiffening. These results demonstrate that long-range interaction between contractile
cells through the deformation of the medium has the potential to globally shape the structure and mechanics of the bulk gel, leading to a functional structure with modified properties. These modified macroscopic changes can define organizing principles in tissue patterning and morphogenesis.
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All authors Ran Glinowiecki, Shahar Goren, Oren Tchaicheeyan, Bar Ergaz, Robin L. B. Selinger, Yair Shokef, Ayelet Lesman
Earth and Planetary Astrophysics
Variable X-ray flux may explain variable helium escape from the habitable-zone exoplanet LHS 1140b
Collin Cherubim, Tim Cunningham and Jason A. Dittmann
A central goal in
exoplanet science is to understand the conditions under which potentially habitable worlds retain atmospheres. This question is of special interest for worlds orbiting M
stars, whose habitable-zone
planets are more readily observable, but which also emit prolonged high-energy radiation that can erode planetary atmospheres. For one such world, LHS 1140b, a rocky
planet orbiting in the habitable zone of an inactive
star, time-variable helium absorption has been observed as the
planet transited in front of its host
star, consistent with atmospheric escape. We present X-ray/ultraviolet flux observations with the XMM-Newton space
telescope, which serve to test whether the observed helium absorption variability can be explained by
stellar XUV flux variability. We detect X-ray flux variability with an amplitude of $F_\mathrm{max}/F_\mathrm{min} = 8.5^{+9.4}_{-4.4}$ within the 18-hour observing window. We do not detect variability in the UV or visible flux. The integrated X-ray flux is fully consistent with the X-ray flux measured in 2018, suggesting stable XUV flux over years-long timescales. We find that the 2018 observation was not sensitive to the level of variability observed in 2026. We explore several models that fit both
datasets and conclude that short-term XUV variability and/or small
flares are more likely to explain the helium variability than long-term XUV variability. Simultaneous observations of the
planet-transit in the near-infrared and
stellar activity indicators like XUV flux are critical to confirm the link between the observed helium signal variability and the observed X-ray variability.
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Mathematical Physics
Locality of KMS states for infinite fermionic lattice systems
Lennart Becker
We study how thermal
equilibrium states of infinite fermionic
lattices respond to perturbations of the
Hamiltonian. Our main result concerns extensive perturbations of a chosen KMS state. We show that exponential decay of correlations and exponential local indistinguishability under the extensive perturbation yield stretched-exponential decay of correlations for the perturbed state. Neither the initial nor the perturbed state is required to be unique, allowing stability to be studied in the presence of phase coexistence. Our approach uses
Quantum Belief Propagation (QBP), which we establish directly on the underlying $C^*$-
algebra. Combining QBP with Lieb–Robinson bounds, we show implications between decay of correlations, the principle that local perturbations perturb locally, and local indistinguishability, closing the cycle for perturbations of the tracial state under the stated decay, support and uniformity assumptions. For extensive perturbations under uniform clustering conditions, we also obtain a differentiable path of local
equilibrium expectations and bound their change linearly in the interaction norm of the perturbation.
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Quantum Physics
Quantum Fisher Information as the Speed Limit for Multipartite Entanglement
Zain H. Saleem, Da-Wei Luo, Anjala M. Babu et al. (+3 more)
We derive a universal upper bound on the speed of multipartite
entanglement generation. For arbitrary differentiable pure multipartite states undergoing parameter-dependent
evolution, we prove that the rate of change of generalized concurrence is bounded by the square root of the
quantum Fisher information (QFI). The proof follows directly from the symmetric logarithmic derivative formalism, revealing the bound as a consequence of
quantum estimation theory, while a complementary Schmidt-spectrum analysis identifies the conditions for saturation and yields a tighter bound for rank-two bipartitions. We illustrate these results in interacting many-body
spin models and investigate their behavior across the
quantum phase transition of the transverse-field Ising model. At the critical point, we find that the QFI can be strongly enhanced while the generalized concurrence is nearly stationary and its sensitivity to the coupling is suppressed. This demonstrates that the enhanced parameter sensitivity associated with
quantum criticality need not arise from rapid changes in the magnitude of multipartite
entanglement.
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All authors Zain H. Saleem, Da-Wei Luo, Anjala M. Babu, Ting Yu, Stephen K. Gray, Anil Shaji
Cosmology and Nongalactic Astrophysics
Observational Evidence of Velocity Anisotropy Assembly Bias in Galaxy Clusters
Facundo Rodriguez, Andrea Biviano, Ravi K. Sheth et al. (+2 more)
Cosmological simulations show that
halo clustering depends on secondary internal properties beyond mass, an effect known as assembly bias. In particular, numerical models have shown that internal velocity anisotropy ($\beta$) is the
halo property most tightly linked to secondary
halo bias: at fixed mass,
haloes with isotropic velocity profiles are more strongly clustered, whereas
haloes in which radial motions dominate are more weakly clustered. Despite this robust theoretical prediction, direct observational detection of velocity anisotropy assembly bias has remained elusive. Here we present observational evidence for this effect using a sample of massive
galaxy clusters from the eROSITA and DESI surveys. We measure the internal orbital anisotropy $\beta$ for 91 clusters via Jeans dynamical modelling with MAMPOSSt, considering three anisotropy profile models to ensure robustness. We divided the sample into two subpopulations: isotropic and radially anisotropic, verifying that they show no significant differences in
halo mass. To quantify their large-scale clustering, we measured the projected cross-correlation function with We report evidence of velocity anisotropy assembly bias: clusters with isotropic internal kinematics exhibit stronger clustering than radially dominated ones, a segregation that is unlikely to be attributable to residual differences in cluster mass. This trend shows varying significance across three anisotropy profiles, from a mild tendency to a highly pronounced signal. Furthermore, the assembly bias remains distinct when restricting the sample to clusters consistently classified across all three models.
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All authors Facundo Rodriguez, Andrea Biviano, Ravi K. Sheth, Antonio D. Montero-Dorta, Manuel Merchán
High Energy Physics (Phenomenology)
Milky Way White Dwarfs as Inelastic Dark Matter Detectors
Javier F. Acevedo
We show that white
dwarfs in the
Galactic Center are a sensitive probe of inelastic dark matter (IDM) annihilation. IDM particles traversing a white
dwarf may become gravitationally captured without fully settling in its interior if their energy drops below the kinematic threshold for inelastic scattering. In this regime, a fraction of the incoming particles remains bound on long-lived orbits that extend beyond the white
dwarf's volume, enabling annihilation to partially proceed outside of the object. Some of the annihilation products subsequently escape, rather than being absorbed by the
stellar material, producing a potentially detectable signal. We estimate the collective gamma-ray flux from the external annihilation sourced by these systems, as a function of the IDM parameters, and compare it to H.E.S.S. observations within the central degree of the
galaxy. From this comparison, we derive tentative limits on the IDM scattering cross-section at the TeV mass scale, under largely conservative assumptions for the IDM density in this region. As a concrete application, we map these results into specific parameter constraints for dark
photon-mediated and higgsino models with mass splittings at the MeV scale.
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Strongly Correlated Electrons
Read-Rezayi fractional Chern insulators in modulated Bernal graphene
Ruth Mora-Soto, André Grossi Fonseca, Raul Perea-Causin et al. (+3 more)
Fibonacci anyons provide a universal platform for topological
quantum computation, and emerge as low-energy excitations in the $\mathbb{Z}_3$ Read-Rezayi phase in the fractional
quantum Hall effect. However, realistic microscopic realizations of this phase in the absence of a
magnetic field have remained elusive. We study a model of periodically modulated Bernal
bilayer graphene with gate-screened Coulomb interactions. Using the recently developed target-phase optimization method in conjunction with band-projected exact diagonalization, we identify at filling $\nu=3/5$ a region of parameter space whose ground state is consistent with a Read-Rezayi fractional Chern
insulator. The partially filled band from which it arises is a part of a two-band complex which mimics
geometric aspects of the lowest and first Landau levels, with the ground state at $\nu=1/2$ consistent with the Moore-Read state. Our results suggest that modulated Bernal
graphene can realize delicate non-Abelian fractional
quantum Hall states at zero
magnetic field, while demonstrating target-phase optimization as a practical route to discovering such phases in realistic, high-dimensional microscopic models.
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All authors Ruth Mora-Soto, André Grossi Fonseca, Raul Perea-Causin, Hui Liu, Emil J. Bergholtz, Marin Soljačić
High Energy Physics (Theory)
Nonlinear electroweak sphaleron clouds around Kerr black holes
Carlos Herdeiro, Jutta Kunz, Hendrik Mennenga et al. (+1 more)
Kerr black holes and electroweak sphalerons are remarkable solutions of two pillars of modern physics: General Relativity and the Standard Model of particle physics, respectively. In this work, we investigate their interplay by constructing nonlinear sphaleron clouds around Schwarzschild and Kerr black holes in the probe limit. We first revisit static and spinning (multi-)sphalerons in flat spacetime, using the measured electroweak parameters. We then explore the domain of existence and physical properties of the corresponding black-hole configurations, revealing a rich branch structure. Remarkably, the sphaleron clouds retain a finite mass gap and do not approach linear clouds within the families studied, distinguishing them from the familiar clouds associated with the onset of superradiant instabilities. We also obtain a closed-form leading-order
Higgs solution on an exact Yang-Mills configuration in a Schwarzschild background.
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All authors Carlos Herdeiro, Jutta Kunz, Hendrik Mennenga, Eugen Radu
Solar and Stellar Astrophysics
Probing the Nature of the Circumstellar Material Surrounding SN 2024ggi: A Search for Precursor Emission and Constraints from Radio Observations
Tobias Géron, James K. Leung, Maria R. Drout et al. (+8 more)
We present an analysis of the pre-explosion optical light curve and post-explosion
radio observations of the nearby
supernova (SN) 2024ggi, a Type II SN discovered in NGC 3621 at a distance of ~7.2 Mpc. Early spectra confirmed that SN 2024ggi showed “IIn-like” features, suggesting the presence of dense circumstellar material (CSM). We searched for precursor emission in the light curve up to 8 years pre-explosion from ATLAS using ATClean, which cleaned the light curve and effectively convolved it with rolling Gaussians of several timescales. No significant evidence for precursor variability was found. We find 80% detection thresholds on the absolute magnitude of -11.28 mag and -8.98 mag for outbursts with timescales of 2 and 300 days, respectively. Our
radio observations taken with the Australia
Telescope Compact Array (ATCA) are consistent with a wind-like CSM density profile, with an inferred mass-loss rate of ${\sim} 8 \times 10^{-5} M_\odot$ yr$^{-1}$, assuming $v_{\rm wind} = 50$ km s$^{-1}$. However, including CSM density estimates from the literature implies a two-component structure in the overall CSM density profile, with a denser inner structure at smaller radii ($\lesssim 6\times10^{14}$ cm) and an extended wind-like profile at larger radii. We conclude that the dense CSM around SN 2024ggi is likely not deposited there by eruptive outbursts. Instead, we favor a scenario with a lower but more stable mass-loss rate, such as pulsation-driven superwinds, a model with extended chromospheres, or a combination of both.
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All authors Tobias Géron, James K. Leung, Maria R. Drout, Rami Z. E. Alsaberi, W. V. Jacobson-Galán, Charles D. Kilpatrick, A. Rest, S. Rest, Stuart D. Ryder, Toshikazu Shigeyama, Yuki Takei
High Energy Astrophysical Phenomena
Correlated Signatures of Plasma Lensing in Fast Radio Bursts
Paz Beniamini and Pawan Kumar
Plasma lensing has been proposed to explain narrow spectra, multiple burst copies, frequency drifts, interference fringes, and polarization changes in fast
radio bursts (FRBs). Because many of these features are not unique to
lensing, a convincing identification requires several correlated observables to be reproduced by one lens model. We derive such relations for a one-dimensional Gaussian
plasma lens near a fold caustic. We distinguish the phase separation of the merging images from their observable group-delay difference and identify three regimes: resolved burst copies, overlapping images with negligible mutual coherence, and coherent spectral interference. We connect the magnification, image delay, spectral-envelope width, fringe spacing, differential dispersion, time-frequency caustic
curvature, and the brightness and ordering of the third image. We derive separate finite-source constraints from large fold magnification and from fringe visibility, and relate the wave-optics magnification scale to the
plasma column of the lens. High-contrast fringes simultaneously constrain the source size and the mutual coherence of the two image fields, which limits the intrinsic coherence of the FRB radiation once the observed spectrum and instrumental bandpass are accounted for. We also derive the conditions for differential Faraday rotation in magnetized lenses. Finally, we show that clean
lensing by a volume-filling turbulent screen requires fine tuning between rare strong fluctuations and caustic confusion, suggesting that sparse sheets, filaments, interfaces, or shocked clumps are more promising
lensing structures.
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Quantum Physics
A Universal Budget for Entanglement and Nonlocal Non-Stabilizerness
Salvatore Marco Giampaolo
Entanglement and nonlocal non-stabilizerness are distinct
quantum resources encoded in the Schmidt spectrum of a bipartite pure state. For
qubit systems, we establish a universal quadratic constraint on their simultaneous allocation, governed by the minimum number of logical
qubits required on each side to encode the occupied Schmidt support. Additional spectral constraints reveal a strong asymmetry in their allocation with the
Entanglement that can exhaust the logical capacity, whereas the maximal nonlocal non-stabilizerness grows only logarithmically with it. For a tensor-network cut crossed by a single separating virtual edge, the logical capacity is determined by the occupied bond dimension. We further derive a one-sided certificate for the resources of the untruncated state from a retained Schmidt spectrum and its discarded weight. For small discarded weight, the resulting corrections are linear in that weight. These results connect a universal resource budget to resource-aware control of tensor-network truncations.
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Strongly Correlated Electrons
André Grossi Fonseca, Aidan Reddy, Ahmed Abouelkomsan et al. (+2 more)
Evidence for
chiral superconductivity has recently been observed in several van der Waals systems including rhombohedral multilayer
graphene and twisted
bilayer MoTe$_2$. In the latter, superconductivity emerges at carrier densities near a fractional Chern
insulator. This raises the question of what kinds of
superconductors may emerge in a system of electrons in a topological band with strong repulsive interactions. Here, we adapt the target-phase optimization method to search for
chiral superconductors in a minimal model of interacting electrons in a Chern band. We construct a differentiable loss function for
superconductors from the sign oscillation of the pair-binding energy and combine gradient-based optimization with a rigorous screening procedure to identify and characterize
superconductors. Applying this framework within exact diagonalization to spinless electrons in periodically modulated Landau levels with screened Coulomb interactions, we uncover a broad family of
chiral superconducting phases. At filling $\nu=2/3$, we recover the previously identified $f-\mathrm{i} f$ hole
superconductors and find additional $p\pm \mathrm{i} p$ and $f+\mathrm{i} f$
superconductors of both electrons and holes, occurring near and far from the limit of ideal
quantum geometry. At $\nu=1/2$, we identify $p- \mathrm{i} p$ electron and $f-\mathrm{i} f$ hole
superconductors and find, for the first time, a direct transition between
chiral superconductors and composite
Fermi liquids. Our results reveal that
chiral superconductivity in Chern bands comprises a diverse landscape of competing pairing instabilities and establish target-phase optimization as a general strategy for searching for
quantum phases in complex interacting systems.
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All authors André Grossi Fonseca, Aidan Reddy, Ahmed Abouelkomsan, Liang Fu, Marin Soljačić
Astrophysics of Galaxies
Quantifying the decline in CO(2-1) intensity around PHANGS-HST star clusters: Constraints on molecular gas dispersal, stellar feedback, and cluster formation efficiency
Hao He, Adam K. Leroy, Erik Rosolowsky et al. (+36 more)
We combine the largest survey of
star clusters in nearby
galaxies to-date, PHANGS-HST, with maps of molecular gas maps from PHANGS-ALMA to constrain the efficiency of cluster formation and the typical timescales over which clusters become dis-associated from their natal molecular gas. We analyse 29,233 clusters in 36
galaxies using CO maps at 150 pc resolution. For each
star cluster with
stellar mass $\geq 10^{3.5}$ M$_\odot$, we measure the radial profiles of CO(2-1) integrated intensity and obtain local background-subtracted CO intensity, $I_{\rm CO}^{\rm bkgsub}$, at cluster centre. We group the clusters by age and mass to quantify the dependence of $I_{\rm CO}^{\rm bkgsub}$ and corresponding molecular gas mass, $M_{\rm mol}$, on these cluster properties. To account for the cluster mass ($M_{\rm SC}$) dependence, we also calculate the normalised mass ratio of $(M_{\rm mol}/M_{\rm SC})$. We find that CO intensity varies systematically with cluster age and mass. Clusters that are spatially associated with H$\alpha$ emission exhibit the highest $I_{\rm CO}^{\rm bkgsub}$ of 7.4 K km s$^{-1}$, corresponding to a $M_{\rm mol}/M_{\rm SC}$ ratio of 82 and implying a cluster formation efficiency ($\epsilon_{\rm obs}$) of $\sim 1.2\%$. Young clusters without associated H$\alpha$ emission show lower and age-dependent $I_{\rm CO}^{\rm bkgsub}$ and $M_{\rm mol}/M_{\rm SC}$, decreasing from 1.3 K km s$^{-1}$ and 15 for clusters with age 1-3 Myr, to a level $\approx$ 0 for clusters older than 9–10 Myr. Clusters older than 10 Myr show no statistical excess of CO intensity. We use the clusters with H$\alpha$ association as initial conditions to model the impact of cluster drift and demonstrate that this is unlikely to drive the observed cluster-gas spatial disassociation on short timescales of 4-6 Myr. Instead, early
stellar feedback seems likely to be the main driver.
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All authors Hao He, Adam K. Leroy, Erik Rosolowsky, Janice Lee, Brad Whitmore, David Thilker, Daniel A. Dale, Frank Bigiel, Annie Hughes, Jiayi Sun, Gagandeep Anand, Ashley T. Barnes, Zein Bazzi, Médéric Boquien, Rupali Chandar, Dario Colombo, Sinan Deger, Simthembile Dlamini, Hamid Hassani, Stephan Hannon, Ralf S. Klessen, Simon C.O. Glover, Kathryn Grasha, Ivan Grasimov, Remy Indebetouw, Kirsten Larson, Lukas Neumann, Elias K. Oakes, Hsi-An Pan, Miguel Querejeta, Lise Ramambason, M. Jimena Rodríguez, Sumit K. Sarbadhicary, Eva Schinnerer, Qiushi Tian, Leonardo Úbeda, Antonio Usero, Thomas G. Williams, Jianwen Zhou
Quantum Physics
Measuring Clock Precision Without an Ideal Time Reference
Pablo Á. Domínguez, Christopher Chubb and Mischa P. Woods
Characterising physical devices typically requires comparison with more precise reference standards. For clocks, however, this approach is problematic because no physically perfect time reference exists; real clocks have finite, model-dependent uncertainty. We address whether multiple imperfect clocks can collectively determine their precision without an absolute reference. This paper provides analytic bounds and protocols for quantifying clock precision using only multiple copies of the same clock, which need not be synchronised and may have manufacturing variations or environmental coupling. Beyond clock characterisation, these methods enable precise measurements f sub-period intervals and relativistic effects such as time dilation and Doppler shifts, providing tools for
quantum metrology and fundamental physics.
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High Energy Astrophysical Phenomena
Discovery of minute-scale polarization angle rotation in a supermassive black hole jet
Aristeidis Polychronakis, Ioannis Liodakis, Dmitry Blinov et al. (+7 more)
Relativistic jets from supermassive black holes oriented towards our line of sight called blazars have puzzled the astronomical community for decades. Their fast jets and preferential
alignment creates a fog of relativistic effects that obscures their true properties. Optical polarimetry - tracing the uniformity, direction, and
evolution of the
magnetic field in the jets, has revealed a unique phenomenon to blazars; coherent changes of the
magnetic field manifesting as rotations of the polarization angle ($\Psi$). The origin of those rotations has been debated for decades with several proposed models to explain them. We detected an extremely fast - minute time-scale - rotation in the polarization angle of $\sim136^\circ$ over the span of about 80 minutes, making it the fastest known rotation by almost an order of magnitude. Our optical polarization observations combined with
radio very long baseline interferometry allow us to reject different models of particle acceleration and strongly point to relativistic effects and the interaction of standing and moving shock waves as the origin of the extreme polarization variations in jets.
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All authors Aristeidis Polychronakis, Ioannis Liodakis, Dmitry Blinov, Anastasia Glykopoulou, Sebastian Kiehlmann, Karan Pal, Georgios F. Paraschos, Lena Debbrecht, Swati Ravi, Herman L. Marshall
Astrophysics of Galaxies
$\textit{N\=ap\=owaw\=a`enakaulua}$: a close quasar pair at cosmic dawn in the Aether survey
Silvia Onorato, Emanuele Paolo Farina, Roberto Decarli et al. (+32 more)
We present the discovery and first characterization of $\textit{N\=ap\=owaw\=a`enakaulua}$: the most compact known
quasar pair candidate in the Epoch of Reionization, with a projected separation of only $0.98^{\prime\prime}$ ($\approx 5.56$ pkpc at $z \sim 6.08$) and a velocity offset of $\Delta v \simeq 15 \text{ km s}^{-1}$. Using spectroscopy from JWST/NIRSpec IFU, as part of the $\textit{Aether survey}$, Gemini/GNIRS and GMOS we characterize the continuum and emission line properties of the two
quasars, enabling constraints on their black hole masses ($M_{\text{BH}} \simeq 1.5 \times 10^9$ and $4.0 \times 10^8\,M_\odot$),
accretion states ($\lambda_{\text{Edd}} \simeq 1.23$ and $1.07$), and systemic
redshifts ($z_{\rm sys} \simeq 6.0781$ and $6.0785$). We place this pair in the cosmological context by comparing the chance of occurrence to extrapolations of high-$z$
quasar clustering measurements at larger scales, resulting in a $\sim 2-3$ order of magnitude excess with respect to expectations. This excess hints at an underlying population of merger-triggered
quasar pairs at
cosmic dawn or to a denser-than-average
galactic environment. $\textit{N\=ap\=owaw\=a`enakaulua}$ thus represents a crucial signpost to investigate the mass assembly of the first massive
galaxies and black holes.
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All authors Silvia Onorato, Emanuele Paolo Farina, Roberto Decarli, Klaudia Protušová, Elia Pizzati, Debora Pelliccia, Devin S. Chu, Larry Lindsey Kimura, Leinani Lozi, Emily Peavy, Fabrizio Arrigoni-Battaia, Eduardo Bañados, Aaron J. Barth, Silvia Belladitta, Manuela Bischetti, Sarah E. I. Bosman, Hyunseop Choi, Tiago Costa, Anna-Christina Eilers, Xiaohui Fan, Simona Gallerani, Thomas R. Geballe, Anniek J. Gloudemans, Eunchong Kim, Brian C. Lemaux, Weizhe Liu, Yoshiki Matsuoka, Chiara Mazzucchelli, Atsuko Nitta, Jan-Torge Schindler, Andrew W. Stephens, Hyewon Suh, Fabian Walter, Feige Wang, Jinyi Yang
High Energy Physics (Phenomenology)
Disentangling $V_{ud}$ from New Physics in Beta Decays with the FCC-ee
Lemonia Gialidi, Elie Hammou, Kamil Laurent et al. (+3 more)
Superallowed
nuclear $\beta$-decays enable the most precise determination of the CKM element $V_{ud}$, but they are only sensitive to an effective combination of $V_{ud}$ and New Physics contributions to left-handed charged currents, which low-energy data alone cannot disentangle. Here we determine $V_{ud}$ simultaneously with the relevant Wilson coefficients of the Standard Model Effective Field Theory (SMEFT) by combining, within the SMEFiT framework, a dedicated likelihood for superallowed transitions, including radiative and
nuclear-structure uncertainties, with LEP and LHC world data and HL-LHC and FCC-ee projections. Current
collider data and HL-LHC projections only partially lift the degeneracy between $V_{ud}$ and possible New Physics effects. Instead, the FCC-ee fully decouples $V_{ud}$ from New Physics, recovering SM-level precision while significantly tightening the constraints on the SMEFT Wilson coefficients. This conclusion is robust against variations in flavour assumptions and theory uncertainties. Our results highlight the complementarity between future
colliders and low-energy experiments, and pave the way towards a SMEFT-consistent interpretation of first-row CKM unitarity tests and the Cabibbo angle anomaly.
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All authors Lemonia Gialidi, Elie Hammou, Kamil Laurent, Vaisakh Plakkot, Juan Rojo, Jordy de Vries
High Energy Physics (Phenomenology)
Neutrino Direct Simulation Monte Carlo: Accurate modeling of out-of-equilibrium decaying cosmological relics
Kensuke Akita, Miguel Escudero, Oleksii Ihnatenko et al. (+1 more)
We consider nonstandard cosmologies in which decaying relics inject energy at MeV temperatures, driving
neutrinos out of
equilibrium. The subsequent
neutrino evolution shapes predictions for the
cosmic radiation density and
primordial light element abundances. Earlier work introduced
Neutrino Direct Simulation Monte Carlo ($\nu$DSMC), which describes
neutrino transport through Monte Carlo sampling of particle interactions. Here, we extend this method by jointly evolving the relic population,
neutrino spectra, electromagnetic
plasma, and
cosmic expansion, and coupling this
evolution to Big Bang nucleosynthesis. The framework includes direct and inverse decays of the relic,
neutrino flavor conversion,
quantum statistics, and pion production by energetic
neutrinos. To reveal the physical impact of these effects and independently test $\nu$DSMC, we compare several approaches to
neutrino evolution across a range of nonstandard cosmological scenarios. We find excellent agreement with independent solutions of
quantum kinetic or quasi-classical Boltzmann equations. Compared with these calculations, $\nu$DSMC includes a broader range of physical processes and is substantially faster for strongly nonthermal
neutrino populations. This makes broad, robust parameter scans for nonstandard cosmologies practical. We show that when departures from thermal
equilibrium are large, approximations that average over
neutrino momenta can give qualitatively incorrect predictions, including the wrong sign of the change in the effective number of
neutrino species and substantially incorrect
primordial nuclear abundances. We conclude that the extended $\nu$DSMC framework enables reliable cosmological tests of new physics by following
neutrino thermalization and its observable consequences.
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All authors Kensuke Akita, Miguel Escudero, Oleksii Ihnatenko, Maksym Ovchynnikov
Quantum Physics
Characterising the precision of a clock without any external time reference
Pablo Á. Domínguez, Christopher Chubb and Mischa P. Woods
Determining a clock's precision usually requires comparison with a better time reference, yet no ideal reference is physically attainable. We show how a single clock can characterise its own precision using only a signal splitter and delayed trigger, whose uncertainty is explicitly accounted for. The resulting
estimator depends only on tick-count statistics. A purpose-built electronic
circuit validates the method without an external timekeeper or a second clock.
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Strongly Correlated Electrons
Emergent low-energy many-body Hilbert spaces in Chern bands
Chen-Xin Jiang, Zi-Xiang Hu and Bo Yang
We show that in Landau levels and more generic Chern bands, the most relevant many-body subspace selected by realistic two-body interactions alone (e.g., in the limit of vanishing bandwidth and band gap) depends strongly on the particle density and can be constructed systematically. Using the well-defined hierarchical structure of conformal
Hilbert spaces (CHS), each with a highest-density
vacuum state, we compute, for both fermionic and bosonic systems, the many-body
quantum metric that quantifies the interaction energy scales of these subspaces. For a large family of short-range, Coulomb-based interactions, particles preferentially occupy the many-body states in the smallest accommodating CHS. This allows us to describe the low-energy physics of the interacting system in terms of the appropriate anyonic degrees of freedom. Our results also explain why, in any Chern band (in
lattice or continuum systems), band mixing tends to be suppressed even in the limit of strong interaction; this suppression is stronger when the band deviates less from the ideal trace condition and when the two-body interaction is shorter-ranged.
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Quantum Physics
Probing the classical complexity of quantum dynamics experiments
Thomas Schuster and Andreas Elben
A confluence of recent works has shown that many
quantum circuits and dynamics are efficiently simulable by classical
algorithms that track local information, even when conventional complexity measures such as the
entanglement and magic are high. Here, we introduce a novel measure of complexity, the reactivity, to capture this new method of classical attack. Unlike conventional complexity measures, the reactivity does not capture a property of a
quantum state or operator in isolation, but rather a
quantum experiment as a whole. We provide numerical and rigorous evidence that
quantum experiments with low reactivity are simple by a host of measures: they are efficient to classically simulate, learn, and fast-forward. This motivates the search for
quantum experiments with high reactivity, which may evade these simplistic features. To this end, we introduce easily implementable experimental protocols—dubbed Pauli path spectroscopy—that allow one to efficiently measure the reactivity of any
quantum experiment of interest. Our protocols are applicable even when the experiment itself is beyond the reach of classical simulation.
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High Energy Physics (Theory)
Localizing the M-Theory Path Integral
Pietro Benetti Genolini, Florian Gaar, Jerome P. Gauntlett et al. (+2 more)
We propose a supersymmetric localization formula for the local perturbative contribution to the M-theory path integral, reducing it to an integral over equivariant flux data. Relative equivariant extensions of the eleven-dimensional Chern–Simons couplings determine the localized action, while for M2-brane backgrounds a tangent-cotangent character computes the one-loop determinant. This gives the first closed form expression for the complete perturbative ABJM partition function at general squashing and chemical potentials, and new analytic results for the ABJM topologically twisted index describing black holes. Applied to the non-toric $V^{5,2}$ theory, the same prescription yields a closed analytic Airy constant previously known only numerically. Our formulas reproduce all available independent field theory results, and provide analytic predictions at general parameters where no field theory answer is currently known. We derive an all-genus result for the Type IIA expansion which is an equivariant form of the usual topological string constant map result, and also extract integrated correlators.
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All authors Pietro Benetti Genolini, Florian Gaar, Jerome P. Gauntlett, Jaeha Park, James Sparks
High Energy Physics (Phenomenology)
Impact of Helicity-Isospin Convention Matching on the Extraction of $\alpha$ from $B^0\to(\rho\pi)^0$
Radek Žlebčík
We show that the $\rho\to\pi\pi$ helicity convention used in the time-dependent Dalitz-plot measurements of $B^0\to(\rho\pi)^0$ decays does not match the convention assumed in the subsequent isospin analysis. Once corrected, the tension between the direct determination of the unitarity-triangle angle $\alpha$ from these decays and its indirect determination from global fits decreases from $2.9\sigma$ to $2.1\sigma$. Combined with the $B\to\pi\pi$ and $B\to\rho\rho$ modes, the direct determination becomes $\alpha = (87.0^{+11.8}_{-4.7})^\circ$, compared with the original world average $(84.1^{+3.7}_{-3.0})^\circ$.
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