High Energy Physics (Theory)
Carroll-Weyl gauged null strings in AdS
Sarthak Duary and Sourav Maji
We study the Carroll-Weyl gauged null string in the Poincaré patch of $\mathrm{AdS}_D$ and its BRST quantization. In Poincaré coordinates $X^A=(z,x^i)$, the radial conformal Killing vector $K=\partial_z$ becomes homothetic in a suitable conformally related frame. A field-dependent rescaling of the homothetic
Hamiltonian constraint then leads to the radial-adapted basis $\mathcal{M}=\frac{1}{2}(P_z^2+P_iP^i)$, $\mathcal{L}=-P_AX'^A$, and $\mathcal{S}=P_z$, with $\mathcal{M}$ invariant along the Carroll-Weyl radial flow. Their modes form a $\mathrm{BMS}_3$
algebra extended by an abelian weight-one current. We classify the central extensions allowed by this residual
algebra and find four independent cohomology classes in the $LL$, $LM$, $LS$, and $SS$ channels. We then construct the associated BRST complex, including the ghost pair for the radial Carroll-Weyl constraint. In the canonical highest-weight first-order representation, only the Virasoro-type central extension is realized: $(c_{LL},c_{LM},c_{LS},c_{SS})=(2D-54,0,0,0)$. Cancellation of the corresponding nontrivial BRST cocycle therefore gives $D=27$ in this representation. This differs structurally from the minimal flat Carroll-Weyl theory, where the dilation constraint $X\cdot P$ gives extra anomaly channels.
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High Energy Physics (Theory)
Generalised Gibbs Ensembles from the ODE/IM Correspondence: the Lee–Yang Model
Sujay K. Ashok, Max Downing, Faisal Karimi et al. (+2 more)
We introduce a systematic scheme for constructing the ODE/IM counterpart of generalised Gibbs ensembles, and apply it to the chiral sector of the Lee–Yang conformal field theory. We encode the chemical potentials in a deformation of the cubic oscillator, fixed order by order by requiring that the large-energy WKB period reproduces exactly the driving term of the corresponding thermodynamic Bethe ansatz equation; the subleading WKB periods then yield, as predictions, the deformed
eigenvalues of the local conserved charges. We work out the
spin-5 ensemble in detail for two states of the model: the ground state, in the module of the primary $\phi$, dual to the deformed cubic oscillator, and the primary of the identity module, dual to the same oscillator supplemented by an apparent singularity, a double pole whose position is fixed by a trivial-monodromy condition. In both cases, the Stokes multiplier obeys the Lee–Yang Y-system, and the deformed
eigenvalues match, to the orders checked, an independent conformal-field-theory computation. The Borel resummation of the resulting series for the ground-state energy reproduces the numerical TBA solution over many orders of magnitude in the chemical potential. The scheme relies only on general features of the ODE/IM correspondence and applies to generalised Gibbs ensembles in other integrable models.
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All authors Sujay K. Ashok, Max Downing, Faisal Karimi, Adarsh Sudhakar, Roberto Tateo
Quantum Physics
Nonlinear Feedback in Josephson Circuit Optimization: Application to a Kerr-Reversal JTWPA
Emanuele Palumbo, Alessandro Alocco, Andrea Celotto et al. (+4 more)
Optimizing Josephson-based nonlinear microwave devices is computationally demanding because the straightforward approach requires exploring broad
circuit parameter spaces through expensive nonlinear simulations. Josephson
Circuits Optimizer addresses this problem by using harmonic balance simulations in two stages: fast linear simulations to select promising
circuit configurations according to properties such as impedance and phase matching, followed by nonlinear simulations to optimize their operating conditions. However, pump-induced effects such as impedance renormalization and Kerr-induced modifications of phase matching are not captured during the initial linear stage. We therefore introduce a nonlinear feedback extension that transfers information from the pumped response back to the linear optimization. The approach is investigated using a Josephson traveling-wave parametric amplifier with a reversed-Kerr architecture, whose model is validated against experimental gain measurements. We then evaluate the difference between the linear and pumped response values of a metric based on the input reflection coefficient, while excluding configurations with insufficient third-harmonic suppression. This discrepancy is considered a candidate feedback observable, as it exhibits features similar to the gain landscape, supporting its use in subsequent optimization cycles.
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All authors Emanuele Palumbo, Alessandro Alocco, Andrea Celotto, Luca Fasolo, Bernardo Galvano, Patrizia Livreri, Emanuele Enrico
Quantum Physics
Quantum jumps of sound
Takuma Makihara, Erik Szakiel, Matthew P. Maksymowych et al. (+7 more)
Quantum mechanics predicts that a vibrating object's energy comes in discrete packets, yet no measurement of its position reveals this discreteness. Resolving individual energy levels requires a qualitatively different measurement, one coupling to the resonator's energy rather than its displacement. We use a superconducting
qubit dispersively coupled to a nanomechanical resonator to perform repeated
quantum nondemolition measurements of the
phonon number. An aligned transfer-print technique integrating the
qubit and resonator yields a mechanical lifetime of $T_1 = 2.1$ milliseconds and a dispersive shift of $2\chi/2\pi = 328$ kilohertz per
phonon. We heralded single-
phonon states with 85% fidelity and observed
quantum jumps between the resonator's first excited state and ground state. These discontinuous transitions are a striking manifestation of
quantum mechanics in a massive, vibrating object.
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All authors Takuma Makihara, Erik Szakiel, Matthew P. Maksymowych, Oliver A. Hitchcock, Kaveh Pezeshki, Rachel G. Gruenke-Freudenstein, Mihir Pendharkar, Shannon P. Harvey, David I. Schuster, Amir H. Safavi-Naeini
Quantum Gases
Quantum simulation of material-specific Hubbard models with alkaline-earth atoms
Henning Schlömer, Reuben R. W. Wang, Bo Xing et al. (+2 more)
A long-term goal of
quantum simulation is to faithfully reproduce the low-energy
Hamiltonians of correlated
quantum materials, establishing a direct connection between solid-state experiment, electronic-structure theory, and programmable many-body systems. Here, we introduce an integrated
quantum-simulation architecture based on fermionic alkaline-earth atoms that enables programmable control over the key ingredients of multi-orbital material
Hamiltonians. Long-lived clock states encode synthetic orbitals, their differential polarizabilities generate orbital-selective tunneling, and contact interactions provide multi-orbital Hubbard and Hund couplings. Spatially structured coherent driving on the ultra-narrow clock transition further realizes
symmetry-selective inter-orbital hybridization, while the clock detuning independently controls orbital energy offsets. In this way, the spatial
symmetries of solid-state orbitals can be encoded directly into the effective
Hamiltonian, even though the atoms themselves remain in conventional $s$-wave Wannier orbitals of the lowest optical-
lattice bands. We demonstrate the resulting integrated control using the four-band low-energy
Hamiltonian of the bilayer nickelate La$_3$Ni$_2$O$_7$ as a demanding
benchmark. Self-consistent calculations show that the microscopic parameters obtained from first-principles modeling can be reproduced within a single experimentally accessible
lattice configuration and independently programmed over substantial parameter ranges. Our results establish a general route for translating material-derived multi-orbital
Hamiltonians into programmable ultracold-atom
quantum simulators.
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All authors Henning Schlömer, Reuben R. W. Wang, Bo Xing, Susanne F. Yelin, H. R. Sadeghpour
High Energy Physics (Theory)
All-multiplicity completion of maximally supersymmetric gauge amplitudes
Ilmo Sung
We show that the known six-point constraints on four-point amplitudes are sufficient for completion at arbitrary multiplicity in planar, four-dimensional maximally supersymmetric gauge theory. We construct massless tree amplitudes as formal series in the derivative expansion, with the standard supersymmetric Yang-Mills three-point amplitudes, unbroken R-
symmetry, and parity invariance of amplitudes with only external scalars, holding the scalar labels fixed. For a positive leading four-point contact coefficient, the even coefficients in the logarithmic parameterization are fixed, while every real sequence of odd coefficients is realized by a completion at all derivative orders. The construction uses the field-theory Kawai-Lewellen-Tye bilinear and normalized
matrices of sphere integrals. Exponentiating homogeneous components of their
matrix logarithms varies the odd coefficients independently while preserving locality and factorization through the complete massless multiplet. The six-point conditions are therefore necessary and sufficient for such a completion. Higher-multiplicity consistency imposes no further restrictions on these four-point coefficients once the higher-point contact interactions are chosen consistently with the same
symmetries and factorization conditions.
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High Energy Physics (Theory)
Reconstructing BPS String Charge Cone in 6d N=(1,0) Supergravity
Yuta Hamada, Hee-Cheol Kim and Kai Xu
The tensor branch of six-dimensional $\mathcal N=(1,0)$ supergravity is characterized by a spectrum of BPS strings charged under the two-form gauge fields. Their charges span a cone in the tensor charge
lattice, whose extremal rays are generated by primitive BPS string charges that become tensionless at the boundaries of the tensor moduli space. We develop a systematic procedure, based entirely on effective field theory data, to reconstruct the primitive BPS string generators and thereby determine the complete closed BPS string cone of any 6d $(1,0)$ supergravity theory. The key ingredients are the universal H-string, which allows us to isolate a fixed sector determined by classified LST blocks and gauge anomaly data from the remaining gauge-neutral E-string sector, and a BPS refinement of the Completeness
Conjecture that ensures population of the relevant charge rays. We further show that this reconstruction provides new constraints on the low-energy theory and can rule out candidate EFTs that pass all previously known local
lattice and anomaly consistency conditions. Separately, for theories admitting
geometric tensor bases, we explain how the same reconstruction determines the complete Mori cone of the corresponding Kähler surface.
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Strongly Correlated Electrons
Cooper Instability of a Magnetic Wigner Crystal
Wangqian Miao and Chunli Huang
Recent scanning tunneling microscopy has directly imaged electronic
crystals in rhombohedral hexalayer
graphene, and magnetotransport measurements suggest that superconductivity and charge-density-wave order emerge from a common
spin-valley-polarized ferromagnetic metal at nearby carrier densities. Motivated by these observations, we ask whether collective modes in a
magnetic Wigner
crystal can mediate pairing in this setting. We address this question by studying the Cooper problem for two electrons in the first conduction band of the Wigner
crystal. Unlike conventional
phonon-mediated pairing, the collective mode (
boson) energies and single-particle (
fermion) dispersion are comparable scales controlled by the electron density, leaving no small parameter for an adiabatic expansion. Moreover, because the
magnetic Wigner
crystal is not time-reversal invariant, the usual Cooper logarithmic divergence in the pairing susceptibility is absent, so the attraction must exceed a finite threshold for pairing to occur. These unusual features motivate a numerical experiment to see whether the
crystal's own vibrations can bind electrons. We obtain the crystalline ground state and its collective mode spectrum within Hartree–Fock and time-dependent Hartree–Fock approximation, and derive the electron–
phonon Hamiltonian using the quasiboson approximation. Solving the resulting two-electron problem, we find that
phonon-mediated attraction exceeds the pairing threshold, with chiral $p$-wave pairing as the leading instability. Within these approximations, we show that collective modes of a Wigner
crystal can indeed favor chiral pairing despite broken time-reversal
symmetry. Our results provide an encouraging starting point for developing a full many-body theory to study electronic crystallization and superconductivity.
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Soft Condensed Matter
Beyond Dry Flocking: Shape-Dependent Hydrodynamic Alignment
Abhishek Thakur, Taniya Khatun, Soumyadeep Kundu et al. (+3 more)
Flocking results from dynamical
alignment among neighbors in a collection of active self-propelling objects. The intervening medium, typically a fluid, however, is not considered to be important for
alignment, except for acting as a momentum sink. The flocking system is therefore described as momentum nonconserving "dry" active matter. Here we investigate a confined system of self-propelled Marangoni swimmers where feedback from the fluid medium, which crucially depends on the shape of the swimmers, influences their
alignment. Using up to thirty partially camphor-coated triangular paper boats as polar swimmers, we uncover a disorder-to-order transition, and an unusual re-entrant order-to-disorder transition, as functions of camphor concentration and swimmer density, respectively. We reproduce these transitions by formulating a reaction-
diffusion model for the camphor field, coupled to the swimmer dynamics, where propulsion forces arise from surface tension gradients. The shape-dependent hydrodynamic interaction discussed here could be central to efficient flocking in living organisms too.
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All authors Abhishek Thakur, Taniya Khatun, Soumyadeep Kundu, Nitin Kumar, P. Parmananda, Anirban Sain
High Energy Physics (Theory)
Large Charge Jets in $\mathcal{N}=4$ SYM Energy Correlators
Alba Grassi, Cristoforo Iossa, Luigi Tizzano et al. (+1 more)
We compute the energy-energy correlator in a state created by a heavy canonical operator of scaling dimension $\Delta_H$ in $\mathcal{N}=4$ $SU(N)$ SYM, at fixed $N$ and arbitrary values of the large charge 't Hooft coupling $\lambda \sim \Delta_H g_{\rm YM}^2$. The state created by the canonical operator triggers spontaneous breaking of conformal
symmetry and the
Higgs mechanism, with squared W-
boson masses proportional to $\lambda$. We start with the known finite-coupling result for the underlying four-point function of local operators, perform the detector and
Fourier transforms and express the resulting energy-energy correlator as an infinite OPE sum in the source-detector channel, which we then analyze both numerically and analytically. We show that the finite-coupling energy-energy correlator exhibits a hierarchy of distinct physical regimes as a function of $z=(1-\cos\theta)/2$, where $\theta$ is the angle between the detectors. A small-angle
vacuum-dominated behavior at $z\ll\lambda^{-1}$ is followed by a non-monotonic medium-induced transient behavior at $\lambda z \sim1$. A large charge jet regime follows, where the energy-energy correlator displays a power-law behavior $\sim1/(\lambda z^3)$ for $\lambda^{-1}\lesssim z \lesssim \lambda^{-1/3}$, before approaching an angle-independent plateau at larger angles.
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All authors Alba Grassi, Cristoforo Iossa, Luigi Tizzano, Alexander Zhiboedov
Strongly Correlated Electrons
Symmetric Mode Ansatz: Theory of Magnon Collective Modes in Chern Insulators
Miguel Gonçalves, Jonah Herzog-Arbeitman, Juan Felipe Mendez-Valderrama et al. (+3 more)
Moiré materials host integer and fractional Chern
insulators (FCIs) where time-reversal is broken spontaneously by flat band ferromagnetism. In twisted MoTe2, unlike in
quantum Hall, opposite
spins carry opposite Chern numbers and realize Ising ferromagnetism with gapped
magnon excitations. Clarifying the nature of these collective modes and the origin of the
magnon gap is key to understanding the stability of the Chern magnets in these materials. To do so, we develop a generalized single-mode approximation, which we call the symmetric mode ansatz (SyMA), to describe the low-energy
magnon spectrum. We find it to be in exceptional agreement with numerical calculations at integer filling, and qualitatively accurate across fractional fillings including FCIs. To explain the accuracy of the SyMA, we present two families of Hubbard models (including the Haldane model and continuum ideal bands) whose collective modes are analytically solvable and for which the SyMA is either exact or an accurate approximation. For a class of these models where SyMA is exact, we prove two-sided bounds on the zero-momentum
magnon gap in terms of the Chern number, Berry
curvature, and
quantum metric, revealing that uniform
quantum geometry is sufficient for stabilizing magnetism in Chern bands.
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All authors Miguel Gonçalves, Jonah Herzog-Arbeitman, Juan Felipe Mendez-Valderrama, Andreas Feuerpfeil, B. Andrei Bernevig, Nicolas Regnault
Quantum Physics
Quantum Networking at the Speed of Quantum Computation: Kilohertz Entanglement in a Heterogeneous Quantum System
Lukas Hartung, Pierre Barral, Noah Glachman et al. (+35 more)
Distributed
quantum computing requires rapid, high-fidelity
entanglement between
qubits in separate processor modules. Photonic links between single-atom
qubits provide switchable, long-range connections, but
photon loss limits their
entanglement rate. Here we entangle a trapped $^{138}$Ba$^{+}$ ion with a silicon-vacancy (SiV$^{-}$) center in a diamond nanophotonic cavity. A
photon emitted by the ion is converted in wavelength and encoding, reflected from the SiV$^{-}$–cavity system and detected, so that a single detected
photon heralds
entanglement. Including all conversion losses, we generate ion–SiV$^{-}$ Bell pairs at an average rate of 1.03(1) kHz with a fidelity of 87.9(7)%. This is four times the rate of the fastest photonic link between two trapped ions and corresponds to one Bell pair per millisecond, matching the cycle time of planned trapped-ion processors.
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All authors Lukas Hartung, Pierre Barral, Noah Glachman, George Toh, Jacob H. Davidson, Sagnik Saha, Alexander Chuang, Matthew C. Cambria, Madison Sutula, Alexander Abulnaga, Julia Brevoord, John Chiaverini, Ian Counts, Aos Dabbagh, Christian Dangel, Skylar Deckoff-Jones, Chawina De-Eknamkul, Jonathan Dietz, Riley Forst, Prithvi Gundlapalli, Jeonghoon Ha, Michael Haas, Ezekiel Meulbroek, Andrea Mucchietto, Daniel Riedel, Jonah Sachs, Jeremy Sage, Mikhail Shalaev, Harriet Shi, Denis Sukachev, Yichao Yu, Christopher Monroe, Nicholas Mondrik, Mihir Bhaskar, Bart Machielse, Matteo Pompili, Carsten Robens, David Levonian
High Energy Physics (Theory)
Scattering entanglement entropy between one particle species and the others
Yuan-Hao Zheng and Jiayin Gu
We construct the
entanglement entropy of a general scattering process between one particle species (denoted as $A$) and the rest of the final state. Assuming a pure initial momentum eigenstate, we show that the reduced density
matrix in particle $A$'s Fock space is block-diagonal in zero-, one- and multi-particle states, and is diagonal in the momentum basis for the one-particle state. As a result, we could write down the Von Neumann
entropy of particle $A$, $S_A$, in terms of scattering probabilities and differential cross sections, assuming no more than one particle $A$ is produced in the final state. $S_A$ contains the information of both the total scattering probabilities (or cross sections) and the differential distributions — the latter depends on a phase-space resolution factor as a result of the infinite-dimensional momentum
Hilbert space. Our result is general and model-independent since we consider the full final state from time
evolution ($S|i\rangle$) rather than a specific outcome, and is applicable as long as the probability for producing multiple particle $A$ is subleading. We also obtain the $n\geq2$ Tsallis and Rényi
entropies in our framework and find out that, at the leading order, they are proportional to the total scattering probability and carry no differential information.
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Quantum Physics
Combining Error Verification and Privacy Amplification in Quantum Key Distribution
Devashish Tupkary, Zhiyao Wang and Ernest Y.-Z. Tan
Quantum Key Distribution (QKD) protocols typically involve two separate steps of error-verification and
privacy amplification. Both steps involve the application of a hash function sampled from a suitable hash family to classical data. A potentially simpler alternative is to implement a single-step hashing procedure, announce and compare a fixed number of bits of its output for error-verification, and retain the remaining bits as the final output key. This reduces the complexity of classical postprocessing, the amount of classical communication, and the amount of randomness needed in the protocol. While this construction has appeared in the literature, a suitable mathematical justification is lacking. In this work, we show that the security of such protocols, under certain simple conditions, follows from a slightly modified notion of secrecy of the protocol without the final error-verification step. In particular, we show that for most
entropy-based proofs, the combined protocol can be implemented with no change to the key rate, and a minor change to the security parameter.
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Earth and Planetary Astrophysics
EK Cha b: multi-tracer detection of a protoplanet candidate in a gas-rich environment
Felipe Alarcón, C. Swastik, Stefano Facchini et al. (+2 more)
Despite sustained community efforts and advances in instrumentation and high-contrast imaging, the search for protoplanets remains difficult, with only two widely accepted systems to date in Class II systems (PDS 70 and WISPIT 2). Here we present the detection of EK Cha b, a new protoplanet candidate, identified through CO emission, millimeter continuum and 0.82 micron broadband photometry, linked to EK Cha, a young late-type M
star. The detection of a new protoplanet candidate offers an additional opportunity to advance our understanding of
planet formation. By exploiting the wealth of archival data available for nearby
star-forming regions, we aim to place EK Cha b in context, characterize its properties, and motivate future campaigns targeting similar systems. We analyzed high-spatial-resolution archival observations of EK Cha from HST, VLT/NACO, VLT/MUSE, and ALMA. We searched for EK Cha b in broadband continuum and gas tracers, reporting the measured flux with uncertainties, and upper limits for non-detections. EK Cha b shows a spectrally-resolved footprint that matches the CO J=2–1 emission, together with 0.82 micron and millimeter continuum emission. EK Cha b is spectrally resolved in CO J=2–1 emission, kinematically consistent with a circumplanetary disk. Best fits from evolutionary models place EK Cha b as a planetary mass companion, although deeper observations are required to fully confirm its nature. Although giant
planets are uncommon around M dwarfs, these
stars host the highest
planet occurrence rate while remaining severely underrepresented in protoplanet searches. EK Cha b demonstrates that such systems are now within reach, and the advent of extremely large
telescopes and improved high-contrast imaging – where the lower host luminosity relaxes the required contras– will open this overlooked regime to systematic exploration.
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All authors Felipe Alarcón, C. Swastik, Stefano Facchini, Edwin A. Bergin, Gabriele Cugno
Mesoscale and Nanoscale Physics
Millisecond phonon lifetimes in piezoelectric nanomechanical resonators
Oliver A. Hitchcock, Matthew P. Maksymowych, Kaveh Pezeshki et al. (+5 more)
Piezoelectric nanomechanical resonators operating at gigahertz frequencies are a promising platform for
quantum information processing and precision sensing, but
phonon lifetimes have been limited to the microsecond range, widely attributed to the higher intrinsic loss of piezoelectric materials. Here we show that this limitation is not fundamental. Using a fabrication process informed by recent studies of defect-mediated loss in lithium niobate, we combine chemical restoration of ion-milled surfaces with a shadow-mask metallization process to produce lithium niobate phononic
crystal resonators with inferred internal
phonon lifetimes of up to 21 milliseconds at 3.6 gigahertz, corresponding to quality factors exceeding $4\times10^8$ ($f\cdot Q_i > 10^{18}$) at millikelvin temperatures. By systematically varying the electrode-to-resonator spacing, we demonstrate that the measured lifetime is set by external coupling between the device and the measurement
circuit rather than material loss. This establishes that lithium niobate, once fabrication-induced surface damage is removed, achieves an intrinsic quality comparable to the best mechanical materials while remaining an intrinsically piezoelectric platform with strong electromechanical coupling.
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All authors Oliver A. Hitchcock, Matthew P. Maksymowych, Kaveh Pezeshki, Takuma Makihara, Erik Szakiel, Chou-Wei Kiang, Daniel Rugar, Amir H. Safavi-Naeini
Solar and Stellar Astrophysics
Atypical White Dwarfs in Open Clusters
David R. Miller, Ilaria Caiazzo, Jeremy Heyl et al. (+1 more)
Open clusters are powerful laboratories for investigating the formation and
evolution of white dwarfs (WDs), as their well-constrained ages link WDs to their progenitor
stars. This is particularly valuable for atypical WDs, including
magnetic WDs and those with non-hydrogen-dominated spectra, whose origins can be difficult to disentangle in the field. We assemble the largest sample to date of atypical WDs in open clusters: eight non-
magnetic WDs with helium-dominated spectra, five with featureless spectra, and five
magnetic WDs showing hydrogen or helium lines. We find no significant difference between the initial–final mass relations of hydrogen- and helium-atmosphere WDs, nor robust spatial or kinematic differences. The strongest difference from the field is a deficit of non-DAs between $0.8$ and $1.0\,\mathrm{M}_\odot$, where the field predicts $6.0^{+0.8}_{-0.7}$ WDs, yet none are observed, with a probability of only $0.37\%$. Massive
magnetic WDs show a similar deficit: only one of 20 cluster WDs with $M_{\mathrm{WD}}\geq1.0\,\mathrm{M}_\odot$ and $T_{\mathrm{eff}}\geq20{,}000\,{\rm K}$ is
magnetic, compared with 10 of 16 in the field. Together, these deficits are consistent with an additional field population of massive merger remnants, particularly high-mass
magnetic WDs and warm/hot DQs. Such objects may be underrepresented in clusters because young systems provide limited time for certain classes of delayed mergers, while older clusters lose members or dissolve; the field accumulates binary
evolution products over Galactic timescales.
Magnetic cluster WDs consistent with single-
star evolution further suggest mass-dependent
magnetic-field emergence, with fields appearing early in some massive WDs while young lower-mass WDs remain consistent with delayed emergence.
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All authors David R. Miller, Ilaria Caiazzo, Jeremy Heyl, Pier-Emmanuel Tremblay
Astrophysics of Galaxies
Lauri Sassali, Cecilia Bacchini, Aku Venhola et al. (+2 more)
The origin of cold gas
turbulence in
galaxies has long been debated.
Supernovae (SNe), the dominant form of stellar feedback, were thought insufficient to sustain it against dissipation, especially in galactic environments with low
star formation rates (SFRs). We investigate the origin of the neutral atomic gas (HI)
turbulence in dwarf irregular
galaxies, a challenging regime of low masses and SFRs. We build on a recent study of spirals showing that disc flaring prolongs the dissipation timescale, reducing the energy needed to sustain
turbulence and making SN feedback viable. We measure the SN efficiency, that is the fraction of SN energy required to sustain HI
turbulence, in 14 dwarfs, and test whether a "universal" efficiency holds across a sample representative of the
star-forming main sequence. From the observed HI distributions and kinematics, we derive the radial profiles of the HI kinetic energy per unit area and model them as the sum of thermal energy and turbulent energy from SNe, constrained by the observed SFR surface density. We consider pure cold and warm neutral medium (WNM) phases as limiting cases, as well as a mixed two-phase scenario, obtaining the SN efficiency and WNM fraction via hierarchical
Bayesian inference. We find that the observed HI kinetic energy in dwarfs requires only $\lesssim 3\%$ of the SN energy, and that a "universal" efficiency of $\approx 2\%$ explains the HI
turbulence across our main-sequence sample. Our findings suggest that the SN efficiency remains similar across
galaxies with different properties, offering valuable constraint for feedback recipes in
galaxy evolution models.
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All authors Lauri Sassali, Cecilia Bacchini, Aku Venhola, Giuliano Iorio, Antonino Marasco
Quantum Physics
On linearity or non-linearity in machine learning for quantum chaotic dynamics
Francesco Perciavalle, Agostino Gallo, Francesco Plastina et al. (+3 more)
Accurately simulating chaotic
quantum many-body dynamics remains a major computational challenge for classical methods, due to the rapid buildup and spatial spreading of
entanglement during the
evolution. This raises the question of whether machine learning can provide an effective alternative for predicting
quantum dynamics. We address this question by formulating
quantum dynamics as a time-series forecasting problem, using a few-
qubit PXP chain, realizable with Rydberg-atom arrays, as a
benchmark. By varying the initial state, the system spans dynamical regimes ranging from ergodic behavior to
quantum many-body scarring, providing a controlled setting for testing forecasting models across qualitatively different dynamics. We compare two contrasting architectures: an expressive nonlinear
Transformer and DLinear, a simple linear forecasting model. The
Transformer accurately predicts dynamics in the more ergodic regime, but its performance progressively deteriorates as the initial state approaches the scarred limit. In contrast, DLinear remains accurate across the entire family of initial states, with its main deviations consisting of small high-frequency oscillations that have little effect on the overall prediction error. Remarkably, these results show that observables generated by complex
quantum many-body dynamics can be forecast with high accuracy through a simple linear mapping from past to future observations. This reveals that the complexity of the underlying
quantum evolution need not translate into an equally complex forecasting problem.
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All authors Francesco Perciavalle, Agostino Gallo, Francesco Plastina, Gianluigi Greco, Nicola Lo Gullo, Carlo Adornetto
High Energy Physics (Phenomenology)
A Texture of Leptons for the Koide and Alikhanov relations
Alessandro Strumia
Koide and Alikhanov proposed intriguing empirical relations among charged-lepton masses and
neutrino mass splittings, respectively. We present mass-
matrix textures that realise these relations and can jointly account for the observed lepton mixing angles, while yielding predictive correlations among them and the
neutrino CP phases.
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High Energy Astrophysical Phenomena
The Origin of the Fermi Halo-like Emission: A New Model of the Fermi Bubbles
Ilias Cholis, Leo Qiyuan Hu and Yi-Ming Zhong
We study the gamma-ray sky at high latitudes for energies between 0.3 and 900 GeV. We search for a contribution in the high-latitude sky and in the region of the Galactic Stellar
Halo that would be beyond known astrophysical emissions, i.e., the galactic diffuse emission, the isotropic mostly extragalactic gamma-ray background, the Fermi Bubbles, Loop I, the contribution from the Galactic Center Excess, and the known point and extended gamma-ray sources detected by the Fermi-LAT Collaboration. We perform a sequence of template fits to the Fermi gamma-ray data, testing different regions of interest of the galactic sky, utilizing a large set of alternative galactic diffuse emission models, and implementing alternative fitting schemes to assess the impact of increased modeling complexity of the gamma-ray sky. We find that the
halo-like emission recently reported by Totani (2025) is real, but it is likely due to emission from the Fermi Bubbles rather than dark matter annihilation in the Galactic
halo. We provide new templates for the Fermi Bubbles, including an updated model for the Flat Bubbles and a detailed model of their substructures, the Cocoons and the Inner Bubbles. In combination, these components account for the previously reported
halo-like emission. We also estimate the associated fluxes and spectral properties of the Flat Bubbles, the Inner Bubbles, and the Cocoons. This updated model for the Fermi Bubbles provides new input toward understanding their origin.
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Strongly Correlated Electrons
Anthony Rey, Ömer M. Aksoy, Claudio Chamon et al. (+2 more)
We investigate how spontaneous
symmetry breaking and
symmetry-protected
topology compete and cooperate in one-dimensional
quantum spin-1/2 systems. We introduce two families of local
Hamiltonians with $\mathbb{Z}^{\,}_{2}\times\mathbb{Z}^{\,}_{2}\times\mathbb{Z}^{T}_{2}$
symmetry which host a zoo of broken-
symmetry phases with and without gapless boundary
spins, namely, six long-range-ordered gapped phases that differ by their $\mathbb{Z}^{\,}_{2}$-
symmetry-breaking patterns (FM$^{\,}_{x,y,z}$ and Neel$^{\,}_{x,y,z}$), their partner
symmetry-protected topological phases (FM$^{\mathrm{SPT}}_{x,y}$ and Neel$^{\mathrm{SPT}}_{x,y}$), and two gapless phases (gFM$^{\,}_{z}$ and gNeel$^{\,}_{z}$) with incommensurate $\mathbb{Z}^{T}_{2}$-breaking
magnetic long-range order and central charge $\mathsf{c}=1$. Direct transitions between competing gapped phases can be continuous or weakly first order. We demonstrate that continuous phase transition lines have exotic critical properties. For example, a line of deconfined
quantum critical points (between the Neel$^{\,}_{x}$ and Neel$^{\,}_{y}$ phases) described by Tomonaga-Luttinger
liquid theory is terminated by the gFM$^{\,}_{z}$ phase at a Lifshitz tricritical point which exhibits spontaneous breaking of the continuous U(1)
symmetry despite the locality and one-dimensionality of the
Hamiltonian, contrary to a naive expectation from the Hohenberg-Mermin-Wagner-Coleman
theorem. Furthermore, critical lines between
symmetry-protected topological phases with different $\mathbb{Z}^{\,}_{2}$-
symmetry breaking (e.g., Neel$^{\mathrm{SPT}}_{x}$ and Neel$^{\mathrm{SPT}}_{y}$) additionally retain low-energy boundary degrees of freedom, realizing
symmetry-enriched criticality (or a gapless SPT phase). Our results reveal unconventional mechanisms by which competing
symmetry breaking and
topology generate ordered critical phases and multicriticality.
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All authors Anthony Rey, Ömer M. Aksoy, Claudio Chamon, Akira Furusaki, Christopher Mudry
High Energy Physics (Theory)
General Spin-1 Dynamics During Inflation: Microcausality Constraints and Cosmological Collider Signals
Trevor Cheung, Carlos Duaso-Pueyo, David Stefanyszyn et al. (+1 more)
We construct the general theory of a
spin-1 field propagating on an inflationary background consistent with scale invariance, rotations, Bunch-Davies conditions and microcausality. Our Boostless Proca theory generalises the usual massive Proca theory to a Lagrangian with 5 free parameters: 4 corresponding to parity-even terms and a single parity-odd term. We impose three degrees of freedom from the outset and find that microcausality, the statement that field operators vanish outside the lightcone, requires the kinetic terms to be gauge invariant. We couple this
spin-1 state to the inflaton and study the signatures it imprints on cosmological correlators. We find no new signals for the bispectrum meaning that the known signals are the most general thereby providing a very clean model-independent probe of new physics in this leading form of non-Gaussianity. For the trispectrum and higher-point functions, the boostless Proca theory produces new shapes with all 5 parameters in principle measurable.
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All authors Trevor Cheung, Carlos Duaso-Pueyo, David Stefanyszyn, Dong-Gang Wang
High Energy Physics (Phenomenology)
Effective field theory for strong phase transitions
Oliver Gould, Farbod-Sayyed Rassouli and Paul M. Saffin
We show how to construct perturbative effective field theories for strong phase transitions, where the standard tools of high-temperature dimensional reduction fail. By identifying the relevant power counting relations for the couplings, masses and background fields, we construct a controlled perturbative expansion adapted to this regime. We find that the order parameter field remains light at the transition, so that there is a controlled derivative expansion, even though large external fields need to be resummed. The resulting effective field theories for strong phase transitions live in three dimensions and have nonpolynomial field dependence. Applying our framework to a two-scalar model, we verify renormalisation scale cancellation through next-to-next-to-leading order and find decreasing corrections to the latent heat as the perturbative order is increased. Extending to include
fermions and gauge fields, we identify a broad class of models in which strong-transition thermodynamics are systematically improvable.
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High Energy Astrophysical Phenomena
Accreting Neutron Stars in Low-Mass X-ray Binaries
M. C. Baglio, S. E. Motta, A. P. Nitindala et al. (+1 more)
Neutron star low-mass X-ray binaries (NS LMXBs) are systems in which a
neutron star accretes matter from a Roche-lobe-filling companion via an
accretion disc, releasing gravitational energy with an efficiency of order 10-20% of the rest-mass energy. Unlike black holes,
neutron stars possess a solid surface and a
magnetic field, making NS LMXBs uniquely rich laboratories for high-energy astrophysics and dense-matter physics. In this chapter we review the current understanding of
accretion onto
neutron stars in LMXBs, tracing matter from the outer disc radii to the stellar surface across five decades of observational discovery. We survey the principal classes of accreting
neutron star systems - canonical atoll and Z-sources, ultracompact X-ray binaries, accreting millisecond
pulsars, and transitional millisecond
pulsars - and discuss how their spectral states, timing properties, and multiwavelength behaviour encode the physics of the inner
accretion flow. We examine thermonuclear Type-I X-ray bursts as probes of nuclear burning and
neutron star structure, and review the boundary and spreading layers where accreted matter decelerates onto the stellar surface. We discuss relativistic jets and ionised disc winds as regulators of the
accretion-ejection cycle. Finally, we present X-ray polarimetric results from the Imaging X-ray Polarimetry Explorer (IXPE), which for the first time provide new, though model-dependent, constraints on the geometry of the emission regions - disc, corona, spreading layer, and jets - that spectroscopy alone cannot resolve, alongside complementary optical and infrared polarimetric observations.
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All authors M. C. Baglio, S. E. Motta, A. P. Nitindala, J. Poutanen
High Energy Astrophysical Phenomena
Discovery of a Nearby Ultra-fast Magnetic White Dwarf Propeller: Common Pathways to Magnetic Cataclysmic Variables
Antonio C. Rodriguez, Kareem El-Badry, R. Michael Rich et al. (+11 more)
The fastest spinning white dwarfs (WDs), which approach break-up speeds, are found in close binary systems. In the two known
magnetic WD “propellers”, AE~Aqr and LAMOST J0240+1952, the
magnetic WD
spins so rapidly that it ejects the material transferred by its Roche-lobe-filling companion rather than accreting it. We report the discovery of the third such system, 1eRASS J042633.5$-$250226 (1eRASS J0426/Valeria), at only 265 pc, identified by combining SRG/eROSITA and Gaia data via the “X-ray Main Sequence”. TESS photometry shows AE~Aqr-like flaring and orbital modulation with $P_{\mathrm{orb}} \approx 6.62$ hr, and ZTF shows month-long high/low state changes. Phase-resolved Palomar/DBSP spectroscopy confirms the orbital period and yields a donor radial velocity of $K_2 = 202\pm7$ km s$^{-1}$. High-speed Palomar/CHIMERA photometry detects optical pulsations on three nights with the strongest detection at $P_\textrm{spin} = 26.8$ sec, though further observations are needed to confirm this as the WD
spin. Spectral fitting of the donor in the low state reveals a late K-type
star with $T_{\mathrm{donor}} = 4100\pm150$ K. Zeeman splitting in the optical spectrum yields a candidate field strength of $B_{\mathrm{WD}} = 26 \pm 3$ MG, meaning the system will evolve into a polar. Like other WD propellers, the system is X-ray faint ($L_X \approx 7\times 10^{30}$ erg s$^{-1}$), but is not detected in the
radio, and a
spin period is not detected in X-rays by SRG/eROSITA. The proximity of this system and evolutionary model constraints on the timeframe of the propeller phase yield a birth rate density of $\sim8\times10^{-16} \textrm{pc}^{-3} \textrm{yr}^{-1}$, which agrees with that of
magnetic CVs, suggesting that a substantial fraction of
magnetic CVs pass through a propeller phase.
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All authors Antonio C. Rodriguez, Kareem El-Badry, R. Michael Rich, Kevin N. Ortiz Ceballos, Ingrid Pelisoli, Casey J. Law, Kaya Mori, Boris Gaensicke, Edo Berger, Liam Connor, Ilkham Galiullin, Ilaria Caiazzo, Matthew Graham, Samuel Whitebook
High Energy Physics (Phenomenology)
Matter-Antimatter Asymmetry from Dirac-Majorana Flip-Flop
Debasish Borah, Arnab Dasgupta, Debalina Nandy et al. (+2 more)
The observed matter-antimatter asymmetry can be generated dynamically via leptogenesis, where a non-zero lepton asymmetry is generated first and then gets converted into baryon asymmetry via sphalerons. Creation of non-zero lepton asymmetry typically requires lepton number violation (LNV) which, within the seesaw framework, results in the Majorana nature of light
neutrinos. With no signs of LNV at terrestrial experiments, we propose a novel leptogenesis scenario where LNV occurs at high temperatures while zero-temperature physics is consistent with the pure Dirac nature of
neutrinos. In a concrete model of this "Dirac-Majorana flip-flop", the right chiral parts of Dirac
neutrinos initially acquire a large Majorana mass in the early Universe when a singlet scalar field with two units of lepton number acquires a non-zero
vacuum expectation value (VEV), thereby facilitating leptogenesis from out-of-
equilibrium decay of heavy Majorana
fermions. At lower temperatures, the VEV of the scalar singlet gets restored to zero to be consistent with lepton number conservation. A first-order VEV-restoring phase transition can lead to observable gravitational waves, while light Dirac
neutrinos can generate detectable dark radiation at
cosmic microwave background experiments.
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All authors Debasish Borah, Arnab Dasgupta, Debalina Nandy, Indrajit Saha, Harman Singh
Astrophysics of Galaxies
Cosmic Duets II. Growth and accretion in Gaia Multi-Peak dual AGN at Cosmic Noon
M. Scialpi, F. Mannucci, D. Izquierdo-Villalba et al. (+36 more)
We present the first statistical characterization of the physical properties of
Cosmic Duets: dual AGN in the
redshift range 0.5 $\leq$ z $\leq$ 3.0 with projected separations of 1-7 kpc, corresponding to systems in which both AGN are expected to reside within the same merger remnant. We analyze the largest homogeneous sample currently available, consisting of 30 spectroscopically confirmed
Cosmic Duets selected via the Gaia Multi-Peak technique. Using rest-frame UV-to-optical integral-field spectroscopy for all targets, primarily with VLT/MUSE, VLT/ERIS, and Keck/OSIRIS, we spatially resolve the two AGN components and extract separate spectra for each system. We decompose the continuum, emission lines, and Fe II complexes through spectral fitting. We derive black hole masses of log($M_{BH}/M_{sun}$) ~ 7.4-10.1 and bolometric luminosities of log($L_{bol}/erg s^{-1}$) ~ 44.8-47.2, consistent with those of single AGN at similar
redshifts. We finally carry out the first comparison of dual AGN properties with semi-analytical models and hydrodynamical simulations, including L-GalaxiesBH and Astrid. Astrid provides a closer match to the observed black-hole mass-ratio distribution, but its selected systems are predominantly at lower
redshifts, resulting in lower bolometric luminosities at fixed G-band magnitude. L-GalaxiesBH perfectly reproduce the observed parameter space, but it predicts more heterogeneous pairs, with higher primary-bolometric luminosity, lower-mass secondary SMBHs, and higher Eddington ratios, resulting in an excess of near-Eddington accreting AGN due to its adopted
accretion prescription. Our results suggest that, in GMP-selected systems, secondary SMBH growth is more efficient than predicted by current models, leading to more comparable black-hole masses and
accretion power between the two components.
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All authors M. Scialpi, F. Mannucci, D. Izquierdo-Villalba, A. Marconi, J. Singh, M. Volonteri, C. Marconcini, Q. D'Amato, B. Moreschini, M.V. Zanchettin, G. Tozzi, M. Ceci, L. Ulivi, E. Bertola, S. Bonoli, C. Bracci, E. Cataldi, C. Cicone, A. Ciurlo, M. Colpi, G. Cresci, A. De Rosa, M. Dotti, M. Fumagalli, M. Ginolfi, I. Lamperti, E. Nardini, M. Parvatikar, M. Perna, F. Rigamonti, K. Rubinur, B. Sala, A. Sesana, P. Severgnini, C. Spingola, D. Spinoso, G. Venturi, C. Vignali, S. Yeh
High Energy Physics (Theory)
Covariant BCFW for All Masses
Jacob L. Bourjaily and Michael Plesser
We use the massive spinor-helicity formalism to describe a novel construction for massive spinors which allows one to connect the many choices of bases useful in the representation of amplitudes involving massive particles, and we use this to derive a new formulation for the general BCFW shift that is valid regardless whether or which of the particles involved are massive or massless. This formalism should help facilitate a more coherent implementation of on-shell recursion for computing amplitudes involving massive particles in four dimensions.
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High Energy Astrophysical Phenomena
Neutrino flavor conversion alters the lepton-emission self-sustained asymmetry in core-collapse supernovae
Noah Roux, Irene Tamborra and Maryna Mesiura
We solve the
neutrino equations of motion in a half annulus, accounting for two spatial dimensions. At any location in the annulus, the
neutrino momentum is characterized by a polar-angle distribution, two effective azimuthal angles, and an energy distribution. We explore how
neutrinos change their flavor while decoupling from matter in the presence of the
neutrino-driven hydrodynamical instability LESA (i.e., the Lepton-number Emission Self-sustained Asymmetry) during the stalled-shock phase of a core-collapse
supernova. In our setup, LESA is responsible for an excess of $\nu_e$'s ($\bar\nu_e$'s) in the Northern (Southern) region of the annulus. Crossings in the $\nu_e$-$\bar\nu_e$ angular distributions appear in the ELN-depleted Southern region of the annulus, while crossings in the energy distributions of $\nu_e$-$\nu_x$ and $\bar\nu_e$-$\bar\nu_x$ are present throughout the annulus. We find that collisional instabilities drive flavor conversion just before
neutrino decoupling, fast instabilities are prominent in the Southern region of the annulus, and slow instabilities dominate otherwise. Flavor conversion is most efficient in the Southern region and is responsible for a $5$-$10\%$ enhancement of the LESA dipole, independent of the
neutrino-mass ordering. Our findings suggest that direction-dependent flavor conversion can have implications for the development of global
neutrino asymmetries and hydrodynamical instabilities in core-collapse
supernovae.
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