Computational Physics · Cross-listed from math.NA
An Explicit Higher-Order Dual Basis for a Multiplicatively Calderón Preconditioned Electric Field Integral Equation
Bernd Hofmann, Thomas F. Eibert, Francesco P. Andriulli et al. (+1 more)
One of the most effective means to precondition the electric field integral equation (EFIE) discretized with Rao-Wilton-Glisson (RWG) functions is the multiplicative Calderón preconditioner employing Buffa-Christiansen (BC) functions as a basis dual to the RWG basis. It results in a formulation that is free from the dense-discretization and the low-frequency breakdown. To generalize the multiplicative Calderón preconditioner from the low-order BC and RWG basis to higher orders, we utilize B-spline-based basis functions and establish the first explicit high-order dual basis. It can be regarded as a generalization of the BC functions to arbitrary
polynomial degrees and constitutes a fundamental building block for other approaches that rely on a dual basis. Numerical results for the obtained preconditioner demonstrate a low and constant number of generalized minimum residual (GMRES) iterations independent of the number of unknonws and the
polynomial degree for canonical and realistic perfectly electrically conducting (PEC) scatterers; a key to enable the full potential of higher-order bases.
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All authors Bernd Hofmann, Thomas F. Eibert, Francesco P. Andriulli, Simon B. Adrian
High Energy Physics (Phenomenology)
Dimensional Regularisation with Non-Anticommuting $\gamma_5$: Status and Application to the Standard Model
Matthias Weißwange
A consistent all-order treatment of $\gamma_5$ in dimensional regularisation (DReg), as provided by the Breitenlohner-Maison/'t Hooft-Veltman (BMHV) scheme, is essential for high-precision electroweak calculations, but comes at the cost of a regularisation-induced violation of gauge and BRST invariance that must be reinstated via
symmetry-restoring counterterms. We report on the current status of our research on the BMHV scheme, from its $D$-dimensional realisation and its multi-loop behaviour up to the 4-loop order, to its most recent application: the complete 1-loop renormalisation of the Standard Model (SM), including both divergent and finite
symmetry-restoring counterterms. For the latter, we discuss the main intricacies of the BMHV treatment and present a representative excerpt of the resulting counterterms.
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Astrophysics of Galaxies
mitigating the overcooling problem with sink-based bursty star formation in a high-z dwarf galaxy
Cheonsu Kang, Taysun Kimm, Daniel Han et al. (+4 more)
Star formation is a fundamental driver of
galaxy evolution, yet many
galaxy formation models still fail to regulate it realistically, allowing gas to collapse too efficiently and overproduce
stars. To investigate a possible solution to this overcooling problem, we perform cosmological zoom-in radiation-hydrodynamics simulations of a dark matter
halo reaching $10^{10} M_\odot$ at $z=6$, adopting two distinct
star formation models: a Schmidt-type model, in which
star formation criteria and efficiency per free-fall time are tied to local gravo-thermo-turbulent conditions, and a sink-based model, in which
star formation is governed by local gas inflows. The sink-based model naturally produces bursty
star formation through rapid
accretion onto young sink particles embedded in strongly convergent gas flows. The resulting intense radiation ionizes and disperses
star-forming clumps through photoionization heating before the first
supernova explodes. Consequently,
supernovae occur in lower-density environments, imparting greater terminal momentum and driving stronger
galactic outflows. In contrast,
star formation within individual gas clumps is less efficient in the Schmidt-type model, because individual
star formation events locally modify
cell conditions, temporarily suppressing subsequent
star formation and lowering the degree of burstiness. Relative to the Schmidt-type model, the sink-based model yields a total
stellar mass lower by a factor of $\sim3$ and a Lyman continuum escape fraction higher by a factor of $\sim10$ by $z=6$. The bursty model drives stronger metal-enriched
outflows and suppresses excess central
star formation, exhibiting better agreement with JWST observations in gas-phase
metallicity and
galaxy size. Our results suggest that bursty
star formation is a key mechanism for enhancing feedback and alleviating the overcooling problem in
galaxy formation simulations.
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All authors Cheonsu Kang, Taysun Kimm, Daniel Han, Maxime Rey, Fred Thompson, Martin P. Rey, Harley Katz
Mesoscale and Nanoscale Physics
Probing Cooper pair momentum by quasiparticle steering with planar Josephson junctions
Isidora Araya Day, Anton R. Akhmerov and Antonio R. L. Manesco
The Cooper pair momentum in a
superconductor is associated with a phase gradient of the superconducting order parameter. In general, this momentum is small compared to the
Fermi momentum, which makes it challenging to measure. Josephson junctions, however, enable the creation of large phase gradients and transfer of the Cooper pair momentum to quasiparticles via Andreev reflection. In this work we demonstrate that Andreev bound states propagating along ballistic planar Josephson junctions eject into an adjacent normal region at a phase-controlled angle that scales as $\Theta \sim \sqrt{\Delta/ \mu}$, where $\Delta$ is the superconducting gap and $\mu$ is the chemical potential. This angle parametrically exceeds the conventional Cooper pair momentum scale $\Delta/ \mu$, and thus this phenomenon is sizeable even within the Andreev approximation regime $\Delta / \mu \ll 1$. Our results establish phase-controlled quasiparticle ejection as a kinematic probe of condensate momentum transfer: unlike existing probes that detect the Doppler energy shift, the signal appears as a momentum-space deflection of emitted quasiparticles.
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Quantum Physics
Partially-Commutative Polynomial Optimization
Abhishek Mishra, Moisés Bermejo Morán and Stefano Pironio
Semidefinite programming hierarchies for commutative and non-commutative
polynomial optimization represent a powerful computational tool with many applications in
quantum information. In such applications, a given variable is typically not either commuting or non-commuting with all other variables, but instead commutes with some variables and does not commute with others, i.e., the variables satisfy some partial commutation relations. While such partial commutation relations can always be incorporated in a fully non-commutative setting through suitable linear constraints in the semidefinite programming relaxations, exploiting their algebraic properties from the onset can result in more compact relaxations. This leads us to introduce partially-commutative
polynomial optimization, a framework that encompasses commutative and non-commutative
polynomial optimization, allowing for arbitrary commutation relations among the variables. We point out that the underlying algebraic structure is that of a partially-commutative monoid. We present and review several key aspects of such monoids and show how they can be used to build SDP relaxations for partially-commutative
polynomial optimization problems in which the partial commutations are natively implemented in the monomial structure, without the need of additional linear constraints.
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Mesoscale and Nanoscale Physics
Fermion-mediated Casimir effect on mesoscopic rings implementing non-Clifford SWAP$^{\alpha}$ gates
Liang Du, Qing-Dong Jiang and Yijia Wu
The Casimir effect is typically governed by intrinsic material properties and lacks in situ tunability. We show that, in mesoscopic rings, both the magnitude and sign of the
fermion-mediated Casimir interaction can be controlled via the Aharonov-Bohm effect. The resulting interplay between the Aharonov-Bohm phase and the Casimir interaction provides a route to engineer long-range interactions. In particular, this mechanism enables the implementation of non-Clifford SWAP$^{\alpha}$ gates between spatially separated
spin qubits, thereby reducing the overhead for universal
quantum computation and
quantum error correction in
spin-
qubit architectures.
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High Energy Physics (Phenomenology)
Dark Phoenix: dark matter relic from its own decay
Debasish Borah, Satyabrata Mahapatra, Indrajit Saha et al. (+2 more)
We propose a novel mechanism for generating correct relic of dark matter (DM) which otherwise gets thermally overproduced from the conventional freeze-out mechanism. The mechanism, dubbed as Dark Phoenix, relies on a transient decay window for DM after its freeze-out which brings its relic within observed limits. Due to finite-temperature effects on masses, DM $\psi$ becomes heavier than its dark sector partner $\phi$ in this window allowing it to decay. The decay of DM then stops after $\phi$ gets a sudden jump in its mass from a first-order phase transition (FOPT) driven by another scalar $\eta$. The dark sector partner $\phi$, assumed to be a charged scalar, undergoes sufficient pair annihilation during this epoch such that its late decay into DM does not overproduce the latter again. While direct-detection rates of DM remains suppressed due to small couplings, the charged scalar $\phi$ can have interesting signatures like long-lived charged track at
colliders. The associated FOPT can also lead to observable gravitational waves at future experiments like LISA.
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All authors Debasish Borah, Satyabrata Mahapatra, Indrajit Saha, Narendra Sahu, Vicky Singh Thounaojam
Astrophysics of Galaxies
Binary stars as dynamical tracers in globular clusters .II. Evolution of the radial distribution of the binary star fraction
J. Bruce, E. Vesperini, E. Dalessandro et al. (+5 more)
The distinct dynamical environments occupied by multiple
stellar populations in globular clusters play a significant role in many aspects of cluster
evolution, including the dynamics of binary
stars. Recent observational analyses of
Galactic globular clusters have revealed a bimodal radial trend in the binary fraction: the fraction of binaries is enhanced in both the central and outer regions of clusters, with a noticeable minimum in the cluster's intermediate regions. In this paper, we investigate the dynamical origin of this feature and the mechanisms responsible for preserving this bimodality for an extended portion of a cluster's lifetime. We utilize a suite of Monte Carlo simulations that follow the long-term dynamical
evolution of both single-population and multiple-population globular clusters. We investigate how mass segregation and binary disruption function cohesively to produce a bimodal profile, and show that although single-population clusters can briefly generate a similar profile, the effect is weak and transient. Conversely, we show that the structural properties associated with the presence of multiple
stellar populations significantly strengthen and preserve the bimodality. We also show that the effects of long-term dynamical
evolution drive a broad relationship between a cluster's dynamical age and the radial location of the binary fraction minimum, which tends to migrate outward over time. Overall, our results strongly indicate that the typical multi-scale structure of multiple-population globular clusters (initially characterized by a dense and centrally concentrated subsystem of second-population
stars embedded in a more extended first-population system) plays a key role in the origin of the observed bimodal profiles and they further demonstrate the analytical power of binary
stars as dynamical tracers of globular cluster formation and dynamical
evolution.
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All authors J. Bruce, E. Vesperini, E. Dalessandro, M. Cadelano, F. R. Ferraro, B. Lanzoni, G. Beccari, C. Giusti
High Energy Astrophysical Phenomena
Hybrid Simulations of Proton Acceleration at Oblique High-$\beta$ Shocks
Yevhen Kylivnyk, Damiano Caprioli and Luca Orusa
Collisionless shocks in the intracluster and intergalactic medium (ICM/IGM) are expected to energize both electrons and ions. While electron acceleration is revealed by prominent
radio emission, $\gamma$-ray emission from hadronic interactions remains undetected, suggesting that high-$\beta$ (ratio of thermal to
magnetic pressure), low-Mach-number shocks cannot accelerate
protons efficiently. We present three-dimensional hybrid simulations, in which ions are treated kinetically and electrons as a fluid, of quasi-perpendicular (
magnetic obliquity $\vartheta = 80^\circ$) shocks with sonic Mach numbers $M_s \sim 3{-}15$ and
plasma $\beta \gtrsim 15$, representative of cluster environments. We find that weak shocks ($M_s \lesssim 5$) fail to develop significant nonthermal populations, with
cosmic ray (CR) acceleration efficiencies $\varepsilon_{\rm CR} \lesssim 0.1\%$. In contrast, stronger shocks ($M_s \gtrsim 10$) develop clear power-law tails with slopes $q \sim 4.0 $ and reach $\varepsilon_{\rm CR} \sim 3\%$. These results suggest that weak, oblique ICM shocks are generally unlikely to accelerate
protons efficiently. However, reducing $\vartheta$ to $\sim 45^\circ$ leads to substantially higher acceleration efficiencies, indicating that
magnetic obliquity plays a critical role in determining
proton acceleration. Our findings provide a microphysical framework for interpreting
radio relic observations, whose polarization suggests that electrons are accelerated at oblique shocks, and the absence of cluster $\gamma$-ray detections.
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Astrophysics of Galaxies
Binary Stars as Dynamical Tracers in Globular Clusters .I. First Observations of Bimodal Spatial Distributions
M. Cadelano, E. Dalessandro, J. Bruce et al. (+7 more)
We present the first homogeneous study of the radial distribution of the binary fraction across the full extent of six
Galactic globular clusters (GCs) spanning a wide range of dynamical ages, from dynamically young systems to core-collapsed clusters. We measured the radial variation of the binary fraction using a combination of deep optical HST observations and wide-field ground-based data. For the first time, we provide evidence that the binary fraction in GCs does not decrease monotonically with radius, as commonly assumed, but instead exhibits a bimodal distribution characterized by an excess in the outer regions. Specifically, the binary fraction displays a central peak, followed by a minimum at intermediate radii and a rising branch beyond approximately 1-2 half-light radii. The position of this minimum correlates with the cluster relaxation timescale, indicating that it is shaped by long-term dynamical effects of two-body relaxation driving the binary
evolution, segregation, and disruption. The minimum radius also correlates with the A+ parameter derived from the radial distribution of blue straggler
stars, an empirical indicator of the cluster dynamical age, further supporting the interpretation that this feature is due to internal dynamical processes. Numerical simulations presented in a companion paper show that such bimodal distributions naturally arise from the combined effects of binary disruption and mass segregation of the surviving binaries in clusters.
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All authors M. Cadelano, E. Dalessandro, J. Bruce, E. Vesperini, F. R. Ferraro, B. Lanzoni, G. Beccari, C. Giusti, F. Cusano, D. Paris
High Energy Physics (Phenomenology)
Flavorful Interactions of AGN Neutrinos with Dark Matter Spike
S. Abbaslu, Y. Farzan and A. Maleki
IceCube-Gen2 is going to make the dream of precise
flavor ratio measurement for high energy
cosmic neutrinos a reality. Motivated by this prospect, we build a model for the interaction of
neutrinos with the dark matter and study the impact of the
neutrino interaction with the dark matter spike around active
galactic nuclei on the
neutrino flavor ratio measurement. We show that, under certain circumstances, the
flavor measurement by IceCube-Gen2 may discriminate between this model and the standard expectation, $(\nu_e^\oplus:\nu_\mu^\oplus:\nu_\tau^\oplus)\simeq (1/3:1/3:1/3)$, as well as the prediction for a damped
muon source. We discuss how we can derive information about the spike as well as about the characteristics of the dark matter particles composing it by combining the
flavor ratio measurements with the results of the terrestrial experiments determining the
neutrino mass ordering and a potential deviation from the standard model predictions in the measurements of the tau decay modes.
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High Energy Astrophysical Phenomena
Massive Perturbers and Transient Pickup Discs in Disc-Crossing Encounters in OJ 287-like Supermassive Black Hole Binaries
Debojyoti Garain, Jonathan Zrake and Zoltan Haiman
We study the hydrodynamical response of a massive black hole
accretion disc punctured by a lower mass black hole on an inclined, eccentric orbit, as motivated by the quasi-periodic outbursts seen in the blazar OJ 287. Using three-dimensional smoothed particle hydrodynamics simulations, we explore how the secondary black hole's mass and orbital eccentricity, and the disc thickness and viscosity, affect the time variation of mass
accretion onto both black holes. We find that disc-crossing events only lead to significant spikes in the primary black hole's
accretion rate when the perturber is quite massive ($q \gtrsim 0.1$) and that such spikes are delayed by roughly a free-fall time ($\sim$ months for OJ 287) after the first disc-crossing. The orbital eccentricity, disc thickness, and viscosity can influence the amplitude and temporal structure of the response; in particular, higher eccentricity causes larger and less delayed delivery of gas to the primary, however the condition $q \gtrsim 0.1$ seems to be robust. We also show that when the secondary is this massive, it generally acquires a "pickup" disc which could produce its own luminous signature. For systems like OJ 287, the secondary pickup disc can contain $10^{2-3} M_\odot$, which if accreted over a timescale comparable to the orbital period can power near-Eddington secondary luminosities with thermal emission peaking in the UV/EUV.
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Astrophysics of Galaxies
Testing the validity of backward orbit reconstruction for outer Local Group dwarf galaxies in IllustrisTNG-100
Priyanka Verma, Ekta Patel and Louis E. Strigari
Orbits of Milky Way (MW) and M31 satellites in cosmological simulations have been shown to match analytic orbits computed in fine-tuned models of the extended potential of the MW/M31
halos. Using a sample of Local Group (LG) analogs from the Illustris TNG100 simulations, we investigate whether the same is true for LG satellites near the periphery of the LG turnaround radius ($\sim 1\,{\rm Mpc}$), but outside the virial radii of the MW and M31. From both dark matter-only (TNG100-Dark) and full hydrodynamical (TNG100-1) simulations, we track the orbits of
dwarf galaxy analogs and compare them with orbits resulting from an analytic model of the LG potential, which is dominated by the dark matter
halos of the MW and M31, along with, where appropriate, their most massive satellites. We find that the reconstructed orbits of the selected outer LG satellites agree with the simulated orbits to within $\lesssim 10\%$ over the last 6 Gyr, with the scatter increasing with lookback time and reaching $\sim 40\%$ by 6 Gyr. The fact that orbits of outer LG
dwarfs track the analytical models suggests that any excess mass in the outer regions of our LG analogs or the
tidal field surrounding the LG does not affect the orbits of outer LG satellites. Residual differences between the analytic and simulated orbits are likely due to a combination of mass
accretion for the satellites and MW/M31, the non-spherical nature of the MW/M31 potential, and the prescription for dynamical friction in the analytical models.
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Nuclear Theory
Stochastic Similarity Renormalization Group
Rongzhe Hu, Xin Zhen, Furong Xu et al. (+1 more)
By integrating the
quantum Monte Carlo technique into the similarity renormalization group (SRG), we have developed a
stochastic SRG framework (SRGQMC) capable of both free-space two-body and in-medium many-body evolutions. This approach circumvents the combinatorial tensor-space explosion of many-body flow equations by mapping continuous
unitary transformations onto an ensemble of signed random walkers. We
benchmark the SRGQMC against deterministic free-space SRG evolutions of realistic nucleon-nucleon (NN) interactions, as well as against in-medium SRG (IMSRG) many-body calculations with the Richardson pairing model at two- and three-body levels [IMSRG(2)/(3)]. While a deterministic extension to the four-body level [IMSRG(4)] remains unfeasible due to prohibitive computational costs, we have achieved the first IMSRG(4) calculation by using the
stochastic technique, demonstrating a substantial improvement toward the full configuration-interaction limit. This
stochastic framework provides a practical pathway to higher-order IMSRG calculations.
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All authors Rongzhe Hu, Xin Zhen, Furong Xu, Junchen Pei
Strongly Correlated Electrons
Magnetic Field Control of the Néel Vector and Magnon Visibility in Altermagnetic MnTe
Tobias Weber, Niclas Heinsdorf, Shane Smolenski et al. (+11 more)
Altermagnetic order gives rise to momentum-dependent
spin splitting of electronic and magnonic excitations even in the absence of a net magnetization. Here, we investigate the
magnetic field dependence of the
spin-wave spectrum of altermagnetic $\alpha$-MnTe using inelastic
neutron scattering and linear
spin-wave theory. An in-plane
magnetic field continuously reorients the Néel vector by overcoming the weak crystalline anisotropy, while remaining small compared with the dominant exchange scale. We find that this reorientation leaves the
magnon energies and line widths essentially unchanged, but strongly modifies the measured spectral intensity through the transverse-momentum projection. Our results demonstrate a clear separation between the soft orientational degree of freedom of the
antiferromagnetic order and the robust exchange-dominated
chiral magnon spectrum. This combination establishes $\alpha$-MnTe as a platform for reconfigurable
magnon coupling, in which external fields tune how excitations interact with polarized probes without substantially altering their frequency or coherence.
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All authors Tobias Weber, Niclas Heinsdorf, Shane Smolenski, Sawyer Beltz, Alexandre Ivanov, Andrea Piovano, Victor Mecoli, Sean Knapp, Ruiqi Tang, Amir Henderson, A. K. M. Ashiquzzaman Shawon, Taylor Pierce-James, Na Hyun Jo, Denis Karaiskaj
High Energy Physics (Phenomenology)
Seesaw reheating
Yann Mambrini
We introduce the Seesaw Reheating scenario, in which the inflaton transfers its energy to a long-lived intermediate scalar associated with the spontaneous breaking of
lepton number before the Universe is reheated through its decay into right-handed
neutrinos. As a result, the reheating temperature is no longer determined by the inflaton decay width but by the dynamics of the seesaw sector. We derive analytical solutions describing the complete reheating history, revealing two characteristic features of this scenario: the relativistic time dilation of the intermediate scalar, which suppresses its decay and delays the transfer of energy to the thermal bath, and its subsequent transition from a relativistic to a non-relativistic regime, introducing a new characteristic timescale in the thermal history. Together, these effects lead to simple analytical expressions for the reheating temperature. When the intermediate scalar is identified with the field responsible for the spontaneous breaking of
lepton number, the same framework naturally connects the reheating temperature to the origin of
neutrino masses and provides a well-motivated setting for sterile-
neutrino dark matter.
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Statistical Mechanics
Exact Lindbladian Dynamics from Conformal Embeddings and Topological Defects in Conformal Field Theory
Chen Bai
Analyzing the dynamics of physical observables in open
quantum many-body systems is a fundamental but highly challenging task that has yielded very few exact results. In this work, we identify intrinsic conformal structures that restore exact solvability in $(1+1)$D conformal field theories. For $N$ Majorana
fermions with linear mode jumps, the adjoint Lindbladian is triangular on reduced even Majorana monomials, yielding recursive exact Heisenberg
evolution. In Wess-Zumino-Witten models admitting conformal Majorana
embeddings, this hierarchy gives exact dynamics of affine-current products realized as Majorana bilinears, including regimes where the Kac-Moody current
algebra alone does not close. In diagonal rational conformal field theories, Verlinde topological defect lines furnish jump operators whose primary-sector dynamics is exactly diagonal: topological-charge probabilities are conserved, while intersector coherences dephase at rates fixed by the modular $S$
matrix and nonnegative measurement strengths. These examples show that intrinsic conformal structures, such as conformal
embeddings and modular data, can organize exactly solvable open conformal dynamics.
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Strongly Correlated Electrons
The monopole plasma resonance: a smoking gun of 3D $U(1)$ quantum spin liquids
Anish Koley, Saranyo Moitra and Inti Sodemann Villadiego
Certain 3D $U(1)$
spin liquids, such as those arising in dipolar
quantum spin ice, have an emergent monopole which is the source of an emergent
magnetic field that transforms under
symmetries like an electric polarization. As a consequence, these monopoles carry a physical electric charge in their cores and form a
plasma at low temperatures. Due to the monopole coupling to emergent gauge fields, the full system behaves as an electrical
insulator for DC transport, but can display a sharp
plasma resonance analogous to a metal at very low frequencies. This can serve as a clear fingerprint to detect these states in materials. We discuss the optimal conditions to observe this phenomenon in the 3D $U(1)$
spin-
liquid candidate Ce$_2$Zr$_2$O$_7$.
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Mesoscale and Nanoscale Physics
Quantum Oscillation Signatures of $\mathbb{Z}_2$ Monopole Charge in Nodal-Ring Semimetals
Aravind Karthigeyan, Yoonseok Hwang, Bohm-Jung Yang et al. (+1 more)
Topological semimetals host band nodes characterized by quantized invariants that can appear in bulk responses, yet some invariants remain hidden from standard probes. In particular, band nodes can carry secondary topological charges whose transport signatures are still largely unexplored. Here we study three-dimensional nodal-line semimetals in which nodal rings carry both the Berry phase $w_1\pi$ and a $\mathbb{Z}_2$ monopole charge $w_2$. We show that
magnetic quantum oscillations, usually treated as a probe of $w_1$, can directly diagnose $w_2$, with the relevant signal selected by the
magnetic-field direction. For a field along the ring axis, the inner and outer extremal orbits of the toroidal
Fermi surface both encircle the $w_2$-enforced thread and exhibit a topological phase shift $\nu w_2\pi$ in the $\nu$th harmonic, which is accessible through standard phase-resolved
quantum-oscillation analysis. By contrast, for a field applied perpendicular to the ring axis, the relevant extremal orbit exhibits the usual $\pi$ phase shift associated with the Berry phase $w_1\pi$, independent of $w_2$. For weak doping, three-dimensional ABC-stacked graphdiyne is predicted to exhibit the proposed oscillations in a field range accessible with present-day high-field facilities.
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All authors Aravind Karthigeyan, Yoonseok Hwang, Bohm-Jung Yang, Junyeong Ahn
Astrophysics of Galaxies
The Thesan-Zoom project: bursty star formation is incompatible with prolonged dust survival
Enrico Garaldi, Filip Popovic, Rahul Kannan et al. (+11 more)
Cosmic dust is a key regulator of
galaxy evolution, but its build-up and survival in the first billion years remain poorly constrained. We present a systematic analysis of
dust in the thesan-zoom suite of radiation-hydrodynamical zoom-in simulations, which self-consistently model
dust formation, growth, destruction, and its coupling to radiative transfer in
galaxies at $z \geq 3$, a multi-phase ISM and bursty
star formation histories. The simulated
galaxies reproduce the observed trends of
dust-to-gas and
dust-to-metal ratios with gas
metallicity, while showing a
dust deficit at high specific
star-formation rates. They also broadly match observed
dust temperatures and UV-IR spatial offsets. We find that
dust and its properties are strongly time-variable and tightly linked to bursty
star formation, with short-lived IR-bright phases (median duration of $20.3^{+2.3}_{-2.4}$ Myr) and longer
dust-poor phases, naturally producing a correlation between
dust temperature and distance from the
star-forming main sequence. The predicted attenuation at $1500$ Å is low compared to observations, even when including unresolved
dust through post processing, indicating that a mechanism able to shield
dust from strong feedback events is necessary to reconcile our
galaxy formation model with observations. In our model, bursty
star formation prevents the survival of large
dust reservoirs ($M_{dust} / M_{star} \geq 10^{-3}$) over a significant fraction of
cosmic time. This implies that bursty
star formation can produce the observed overabundance of UV-bright
galaxies at $z \geq 10$ only if it rapidly settles down by $z \sim 8$ (where large
dust reservoirs are detected). It is also possible that our models lack physical ingredients or emergent phenomena that aid the survival of
dust. Future observations of high-
redshift dust will be key to diagnose the physical mechanism at play in the first
galaxies.
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All authors Enrico Garaldi, Filip Popovic, Rahul Kannan, Aaron Smith, Ewald Puchwein, Naoki Yoshida, Kentaro Nagamine, Celine Peroux, Laura Keating, Mark Vogelsberger, William McClymont, Xuejian Shen, Sandro Tacchella, Lars Hernquist
High Energy Astrophysical Phenomena
Star-Disk Collisions II: Debris Stream Dynamics and Implications for QPEs and Other Transients Near SMBHs
Philippe Z. Yao, Eliot Quataert, Yan-Fei Jiang et al. (+1 more)
Quasi-periodic eruptions (QPEs) are repeating soft X-ray
nuclear transients with recurrence times of hours-days and
flare duty cycles of $\sim$10-20%. Many aspects of QPEs can be modeled as a
stellar-mass orbiter that intersects an
accretion disk producing a shocked debris cloud and a
flare of radiation. We present three-dimensional Athena++ hydrodynamic simulations of
star-disk interactions around a $10^{6}\,M_\odot$ supermassive black hole, including the black hole's
tidal potential, the disk's Keplerian rotation, and orbital periods similar to those observed. After each disk encounter, freshly stripped
stellar debris exits the Hill sphere to form an extended, asymmetric, roughly triaxial stream. Subsequent stream-disk collisions shock both
stellar debris and disk gas to high specific energies and drive a wind-like
outflow. At larger orbital periods the shocked
stellar debris dominates the high specific energy debris, while at shorter orbital periods the shocked disk energy can be similar. From the shocked
stellar mass measured in the simulations over time, we infer
flare durations set by the time it takes the
stellar debris stream to collide with the disk, consistent with the observed constant duty cycle of $\sim$10-20%, independent of orbital period. The total shocked debris energy is consistent with QPE
flare energetics. Our results favor one observable
flare per
stellar orbit except perhaps at the shortest orbital periods where the shocked
star and disk energetics can be similar. Variations in the stream's center of mass relative to the
star, the stream density, and other properties can produce diverse changes in the time of the
flare's peak relative to the time of the
star-disk collision. We discuss the implications of our results for QPE timing and for other transients in
galactic nuclei.
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All authors Philippe Z. Yao, Eliot Quataert, Yan-Fei Jiang, Itai Linial
Strongly Correlated Electrons
Energetics of fractional anomalous Hall crystals in rhombohedral graphene
Félix Desrochers and Ashvin Vishwanath
Fractional anomalous
Hall crystals (FAHCs) replicate the topological order of the fractional
quantum Hall effect in the continuum without requiring any external
magnetic field. They spontaneously break continuous translation
symmetry like a Wigner
crystal, but are distinguished by each unit
cell holding a fixed fractional number of electrons. Until now, these states have been confined to theoretical speculation or engineered models, leaving open the question of whether they can plausibly emerge in actual physical systems. Here, we establish them as energetically competitive candidate states in a realistic material setting. We study rhombohedral pentalayer
graphene (R5G) with variational wavefunctions that are exact zero modes of a recently proposed ideal model of R5G. We evaluate their energies using Monte Carlo, after reinstating realistic dispersion and screened Coulomb interactions. We find FAHCs to be energetically competitive with integer anomalous
Hall crystals and
Fermi liquids, and their stability follows a simple principle. Each
crystal maps onto a parent
quantum Hall liquid that fixes its interaction energy, while the kinetic energy favors
crystal periods that match the finite-momentum minimum of R5G's Mexican-hat dispersion. A weak periodic potential can then selectively lower and pin the commensurate fractional
crystals. This picture predicts how the integer and fractional
quantum anomalous
Hall stability windows evolve with twist angle and displacement field, which we compare to recent experiments. These results support a continuum-and-interactions-first route to fractional anomalous
Hall states in rhombohedral
graphene.
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High Energy Astrophysical Phenomena
The type Ia supernova 2023vjh: a peculiar 1991bg-like SN with unusually faint light curves
M. Kopsacheili, L. Galbany, G. Folatelli et al. (+32 more)
We present observations of the 1991bg-like type Ia
supernova (SN) 2023vjh, associated with the elliptical
galaxy MCG+04-10-013. Its light-curve shape parameters ($\Delta m_{15}(B)=1.89 \pm 0.01$ mag and $s_{BV} = 0.45 \pm 0.03$), together with its spectroscopic
evolution, place it firmly within the class of fast-declining, subluminous SNe Ia. The near-peak spectra show prominent features of Si II, Ca II, and Ti II, consistent with a cool photosphere, and place SN 2023vjh within the "cool" and extreme cool regions on the classification diagrams. In addition, the three late-phase near-infrared (NIR) spectra display the Ca II NIR triplet, Fe II, and Co II absorptions, but no obvious $H$-band break. Although SN 2023vjh falls in the same regions of the classification diagrams as other well-studied 91bg-like events, it shows some deviation within this class. In particular, it is systematically fainter than predicted by explosion models and fainter than other well-studied 91bg-like SNe. Light-curve fitting and color-based analyses indicate a relatively large reddening ($E(B-V)_{host}\sim$ 0.2 - 0.35 mag), which is unusual for 91bg-like SNe. Yet, the lack of detectable Na I D absorption in its spectra, along with its large projected distance from the center of its passive host
galaxy (6.8 kpc), suggests that interstellar extinction along the line of sight is minimal. SN 2023vjh appears to be fainter than typical 91bg-like SNe, and it could be affected by circumstellar material (CSM). Comparisons with explosion models and alternative extinction prescriptions show that including CSM-like extinction improves agreement in the blue bands, but residual discrepancies in the $i$-band may reflect limitations in the model.
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All authors M. Kopsacheili, L. Galbany, G. Folatelli, M. M. Phillips, C. R. Burns, M. D. Stritzinger, H.-Y. Miao, M. González-Bañuelos, R. García-Benito, T. E. Müller-Bravo, E. Y. Hsiao, K. Auchettl, J. P. Anderson, C. Ashall, T.-W. Chen, D. D. Desai, M. E. Huber, T. de Jaeger, J. M. DerKacy, M. Gromadzki, J. T. Hinkle, W. Hoogendam, C. Jimenez-Palau, K. Matilaine, P. A. Mazzali, K. Medler, T. Pessi, C. Pfeffer, K. Phan, G. Pignata, R. Sanfeliu, B. J. Shappee, M. A. Tucker, H. Xiao, D. R. Young
Astrophysics of Galaxies
What becomes of JWST/NIRCam-selected high-redshift massive galaxies?
Devontae C. Baxter, Alison L. Coil, Ethan O Nadler et al. (+2 more)
Early JWST/NIRCam surveys revealed a puzzling population of high-
redshift massive
galaxy candidates largely absent from previous rest-frame UV surveys. Spectroscopic follow-up has both confirmed and contested these candidates, whose potential overabundance may challenge traditional models of
galaxy formation. In this study we evaluate the reliability of the photometric selections used to identify these candidates in observational data by applying them to
galaxies in the TNG300 simulation with synthetic
dust-attenuated photometry. Among the five observational selection criteria considered, we find that the selection presented by Pérez-González et al. is the most reliable and inclusive. Nevertheless, only 1 of the 18
galaxies at $z\sim5$ with $M_{\star} \geq 10^{11}~\mathrm{M_{\odot}}$ in the simulation satisfies this selection; the remaining 17
galaxies are on average $\sim0.5$ mag bluer than the color selection under the adopted
dust model. We construct an improved JWST/NIRCam color-magnitude selection that provides a more complete census of massive
galaxies at $z\sim5$ in TNG300 while excluding dusty, low-mass
galaxies identified by criteria from the observational literature. We investigate the descendants of the most massive NIRCam-selected
galaxies at $z=7,~4,$ and $2$ in TNG300, finding that they rarely evolve into the most massive
galaxies by $z=0$. In general only the high-
redshift massive
galaxies that undergo substantial late-time ($z\lesssim0.2$) merger-driven growth become the most massive
galaxies in the Universe today. Together these results suggest that current observational JWST/NIRCam selections are not identifying the most massive high-
redshift galaxies, and caution against interpreting high-
redshift massive
galaxies as direct progenitors of the most massive
galaxies at $z=0$.
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All authors Devontae C. Baxter, Alison L. Coil, Ethan O Nadler, Xuejian Shen, Mark Vogelsberger
Quantum Physics
The Apparatus Strikes Back: Momentum Conservation and the Cost of Spatial Superpositions
Lucas C. Céleri, Diogo O. Soares-Pinto and Daniel A. Turolla Vanzella
Preparing massive particles in coherent spatial superpositions is a central objective of modern
quantum science, motivated by applications ranging from fundamental tests of
quantum mechanics and
gravity to
quantum-enhanced sensing. The experimental difficulty of realizing such superpositions is usually attributed to environmental decoherence mechanisms whose impact depends on the details of the experimental implementation. Here we identify a universal constraint arising from momentum conservation and the
quantum nature of the preparation apparatus. Any protocol that places a particle of mass $m$ in a spatial superposition with separation $d$ necessarily entangles the particle with the center-of-mass degree of freedom of the apparatus responsible for the splitting. The resulting
recoil displacement, fixed by conservation of the mass dipole moment, reduces the coherence of the particle when the apparatus is not included as part of the
quantum system. For an apparatus of mass $M$, preserving coherence requires the
recoil displacement to remain smaller than the coherence length of the apparatus center-of-mass state, leading to a quantitative bound expressible as a constraint on its temperature and on how rigidly the apparatus is anchored to the laboratory frame. We analyze the implications of this bound for current matter-wave interferometry experiments, proposals for gravitationally mediated
entanglement, and tests of
quantum mechanics near the Planck scale. Our main result, which may seem counterintuitive, is that the
recoil of even heavy macroscopic apparatuses can pose a surprisingly strong constraint on the coherence of spatial superpositions of particles with masses well below the Planck mass. Finally, we discuss why the resulting limitation should be regarded as a conservative estimate and under which conditions it can be interpreted as an instance of false decoherence.
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Astrophysics of Galaxies
Dark matter density profiles of the Milky Way satellite population: reconciling simulations and observations
Jorge Sarrato-Alós and José María Arroyo-Polonio
The cusp-core problem remains a key challenge for the $\Lambda$CDM model. Historically, comparing inner dark matter
halo slopes ($d\log\rho/d\log r$) from simulations and observations has suffered from a methodological mismatch: evaluating slopes at different radii creates apparent tensions due to inconsistent definitions rather than genuine physical differences. We rigorously compare dark matter density profiles of Milky Way (MW)
dwarf satellites inferred from dynamical modelling against CDM hydrodynamical simulations. Using the NIHAO and FIRE-2 suites ($M_{\star} \sim 10^3$-$10^{11}\,\rm M_\odot$), we confront simulated profiles with dynamical inferences of 16 MW satellites across four methods, strictly within their reliability limits. Crucially, we evaluate simulated slopes at observationally accessible radii, directly comparing profiles at matched
stellar mass. Both observed and simulated
galaxies exhibit a mass-dependent core-formation trend: inner slopes rise from cuspy values ($\approx -1.5$) at $M_{\star} \sim 10^5\,\rm M_\odot$ to core-like values ($\approx 0$ to $-0.4$) at $M_{\star} \sim 10^8\,\rm M_\odot$. Efficient core formation begins at $M_{\star} \gtrsim 10^6\,\rm M_\odot$ for centrals, where satellites display increased scatter consistent with
tidal disruption. Simulated profiles agree with observations within $\lesssim 1\sigma$ for most systems, outperforming a NFW profile. Furthermore, differing observational models present scatter for a given system comparable to the simulation-to-observation offset. Evaluating dark matter density slopes at fixed physical radii significantly improves agreement between hydrodynamical simulations and dynamical models, revealing no clear tension when comparing profiles at fixed
stellar mass, but Willman\,1 remains an unresolved outlier.
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High Energy Physics (Phenomenology)
Renormalon subtracted nonrelativistic QCD for heavy hadron systems
Benoît Assi, Andreas S. Kronfeld, Simon Vaiva et al. (+1 more)
We present a renormalon-subtracted formulation of potential nonrelativistic QCD (pNRQCD) for precision spectroscopy of heavy
hadron systems, combining variational and Green's function Monte Carlo (VMC/GFMC) methods with static two- and three-body potentials through NNLO in $\alpha_s$ (leading order in $1/m_Q$). Minimal renormalon subtraction (MRS) systematically sums leading factorially growing terms, thereby stabilizing perturbative convergence and reducing renormalization-scale dependence. We tune charm and bottom
quark masses to
spin-averaged $1S$ quarkonium states and predict $\Omega_{ccc}$, $\Omega_{ccb}$, $\Omega_{cbb}$, and $\Omega_{bbb}$
baryon masses, as well as QCD-stable
baryons containing top
quarks. NNLO MRS results undershoot
lattice QCD by 125-175 MeV, a difference we attribute to contributions beyond the static perturbative potentials, including $1/m_Q$ corrections. Applying these methods to unequal-mass fully-heavy tetraquarks, we determine the critical heavy-to-light mass ratio for binding and compute binding energies across the mass-ratio landscape.
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All authors Benoît Assi, Andreas S. Kronfeld, Simon Vaiva, Michael L. Wagman
High Energy Physics (Phenomenology)
Carlos Henrique de Lima, Navin McGinnis and David McKeen
We study high-energy
photons produced at a
lepton collider that convert into an $e^+e^-$ pair in the detector, as a tool for measuring
quantum information observables. We consider single- and double-conversion processes in $e^+e^- \to \gamma\gamma$ and $e^+e^- \to e^+e^-\gamma$. Single conversions enable an in situ extraction of the
spin-analyzing power, while double conversions probe polarization correlations. Focusing on the Belle-II detector, we show that, depending on the reconstruction resolution of the opening angle of the conversion $e^+e^-$ pair,
quantum correlations of the diphoton system can be probed. In particular, measurements of violations of the Bell inequality,
quantum discord, concurrence, nonstabilizerness, and steerability with spatially separated GeV-scale
photons can be made at high significance.
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General Relativity and Quantum Cosmology
A Small-Throat Boundary Condition for the Tunneling Wave Function of the Universe
Masaki Yamada
We propose a small-throat prescription for the wave function of a closed universe in the Lorentzian path integral formalism, motivated by the idea that universe creation may be obtained as the decoupling, or pinch-off, limit of a tunneling geometry connected to another universe through a small throat. Instead of retaining the parent-universe side explicitly, we describe the remaining half-geometry by a minisuperspace path integral with boundary conditions imposed at the throat. To model the finite throat, we introduce a small radiation component parametrized by $\epsilon$ in a closed minisuperspace model with a positive cosmological constant. The radiation term produces two turning points, an inner one $q_-\sim O(\epsilon)$ and an outer one $q_+\sim H^{-2}$, where $q$ is the square of the scale factor. Our prescription imposes the Neumann condition $\dot q(0)=0$ at the initial endpoint and restricts the initial size $q_i=q(0)$ to a small-throat domain $0<|q_i|<\sqrt{\epsilon}/H$ that contains $q_-$. This restriction selects the Riemann sheet containing the small-throat tunneling saddle and its Picard–Lefschetz cycle, while excluding the unsuppressed saddle associated with the outer turning point $q_+$. Taking the limit $\epsilon\to0$ after this finite-throat saddle problem has been defined, the small-throat domain collapses to $q_i \to 0$, and the saddle action reduces to that of the standard tunneling saddle. Other choices of lapse contour can instead select Hartle–Hawking-type growing branches. In this sense, the tunneling wave function can be obtained as the limiting form of tunneling from an arbitrarily small universe in a Lorentzian path integral, rather than by imposing a boundary condition directly at a vanishing geometry.
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High Energy Physics (Phenomenology)
The Minimal High-Quality QCD Axion
Mario Fernández Navarro
The canonical QCD
axion is minimal but not high quality. We identify a minimal high-quality QCD
axion, in which the Peccei-Quinn
symmetry emerges as a gauge-origin boundary remnant of five-dimensional $U(1)$ gauge invariance on a flat interval, and the
axion is the surviving Wilson-line phase. QCD and the Standard Model remain four-dimensional, retaining much of the simplicity of KSVZ/DFSZ anomaly sectors. The construction requires no bulk QCD, warping, or color Chern-Simons term, yet retains exponential quality protection. Thus
axion quality is compatible with minimality.
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