Papers

Population III (Pop III) stars are expected to produce extremely hard ionizing spectra, yet direct evidence for their signature–strong narrow He II $\lambda1640$ emission with weak or absent metal lines–remains elusive. Although Pop III formation peaks at $z\gtrsim10$, models predict that nearly pristine gas pockets can survive to later times, making intermediate-redshift searches a probe of metal mixing across cosmic time. We search 109,545 high-confidence Ly$\alpha$-emitting galaxies at $1.9<z<2.3$ in the Hobby–Eberly Telescope Dark Energy Experiment's database for systems with strong He II $\lambda1640$ and no detected UV metal lines, recovering eight candidates and a first-order, tentative comoving number density of $\sim30$ Gpc$^{-3}$. The eight-object stack yields a rest-frame He II equivalent width of $28.7\pm6.7$ Angstrom, He II/Ly$\alpha=0.354\pm0.094$, and a resolution-corrected He II FWHM of $449\pm105$ km s$^{-1}$. We find no significant N V, C IV, or O III] emission; using the He II width to set the scale, we derive $3\sigma$ upper limits of N V/He II $<0.167$, C IV/He II $<0.128$, and O III]/He II $<0.140$. This combination of strong He II, elevated He II/Ly$\alpha$, moderate line width, and weak metal lines is difficult to reproduce with metal-enriched stellar populations, AGN narrow-line regions, shocks, or classical Wolf–Rayet features. We interpret the sample as candidates for very metal-poor or Pop III-like ionizing sources at $z\sim2$. Definitive confirmation requires deeper rest-UV spectroscopy to measure He II and metal-line limits in individual objects, followed by rest-optical spectroscopy of H$\beta$, [O III] $\lambda4959,\lambda5007$, [O II] $\lambda3727$, and H$\alpha$ to constrain gas-phase metallicity, ionization conditions, and AGN activity.

Quantum error correction commonly relies on syndrome measurement, decoding, and conditional feedback. We numerically show that the conditional spectrum of an interacting transmon circuit can compile a local recovery rule into a fixed open-loop control cycle. In a four-bit repetition-code ring, the resulting input-independent control slows the decay of logical coherence under Pauli-\(X\) noise and stabilizes logical-one population under data relaxation relative to uncorrected references. Its local, bounded-degree architecture provides a hardware-native framework for extending compiled recovery control to larger quantum networks.

We construct exact many-body scar towers in two dimensional gauge theories with two flavors of massless fundamental fermions. For oppositely charged fermions, the scar subspace is generated by a gauge-neutral $\eta$-pairing operator, and admits a purely algebraic construction. Exact diagonalization methods reveal anomalously low entanglement and long-range pair correlations in the scar states. Charge conjugation maps the $\eta$-tower to a vector-flavor polarization sector of the equal charge model, yielding an interpretation as a coherent flavor mode with Josephson-like phase dynamics. Finite fermion masses mix the protected pair with an orthogonal channel and destroy the exact tower. The identified scar tower can be algebraically realized in a large family of lattice field theories, revealing a universal character of these states. Our results provide an analytical construction of invariant scar subspaces in a gauge theory with a nontrivial continuum interpretation.

The study of super Riemann surfaces and their moduli led Witten and Felder, Kazhdan and Polishchuk to ask what is the smallest $d$ such that the $d$-th power of the Schottky ideal is contained in the super Schottky ideal. Felder, Kazhdan and Polishchuk proved that $d=g$ in odd genus $g\geq5$ and that $d\in\{g-1,g\}$ in even genus $g\geq4$; Y.~Shen subsequently proved that $d=g$ in even genus $g\geq6$. Thus the only remaining open case was $g=4$. Here we close this gap by showing that in genus $4$ too, the smallest power of the Schottky ideal contained in the super Schottky ideal is $d=g=4$. The question is equivalent to one concerning the codifferential of the super period map. The quadratic odd contribution sends a conormal vector to a bivector, represented by a skew-symmetric $(2g-2)\times(2g-2)$ matrix. The question is to find such a vector for which, at a generic point, this matrix has maximal rank $2g-2$, or $6$ in our case. Our computation uses the standard exact sequences on $C\times C$ attached to the sheaves $\OO(a,b,c)$, together with a degeneration to a vanishing theta-null and some facts about the Szegő kernel. At a curve with a vanishing theta-null, a regularized version of the codifferential can be described by an explicit multiplication map, allowing an easy computation of the rank. This rank turns out to be $4$. A first-order calculation on an explicit deformation of a cyclic trigonal vanishing theta-null differentiates the global Gaussian-map identity for the regularized conormal bivector. Including the variation of the Gaussian map gives a nonzero first normal symbol. The resulting first-order form is nonzero on the null space of the limiting skew-symmetric matrix, so the rank jumps to $6$ on nearby curves, showing that $d=4$.

We present a diagrammatic expansion for thermal expectation values of low-weight Majorana strings in a fixed realization of the $N$-fermion Sachdev–Ye–Kitaev (SYK) model. At each order in the expansion, the observable is expressed as a finite sum of polynomials in the couplings multiplied by temperature-dependent kernels built from the large-$N$ melonic propagator. At fixed $\beta J$, the expansion is organized in powers of $N^{-1/2}$, and each order can be efficiently evaluated with classical resources polynomial in $N$. The expansion also extends to correlations at arbitrary imaginary times and sufficiently short real times. For the four-body SYK model, we show that the diagrammatic predictions give an excellent account of exact diagonalization results at sizes up to $N=24$. We also apply the method to the Maldacena–Qi (MQ) model formed from two identical copies of a fixed SYK realization. This enables the identification of a nearby SYK-like Hamiltonian whose thermofield double state has higher fidelity with the Maldacena–Qi ground state than the thermofield double of the original SYK Hamiltonian.

We present simulations of the microwave sky at 2.5 arcsecond resolution over 100 square degrees, generated from existing full-sky, lower-resolution simulations, and use them to demonstrate extragalactic foreground removal for a CMB-HD survey. Our cleaning method detects and removes the cosmic infrared background and radio galaxies, yielding source catalogs that are 95% complete down to flux limits of 0.008 and 0.04 mJy at 90 and 148 GHz, respectively. It also identifies and removes galaxy clusters via the thermal Sunyaev-Zel'dovich effect, producing a cluster sample that is nearly complete above $M_{500c} = 5 \times 10^{13} M_\odot$. After cleaning, the residual foreground-plus-noise power spectrum of the coadded 90 and 148 GHz temperature map is 50% higher than previous idealized estimates, increasing cosmological parameter uncertainties for an 11-parameter $\Lambda$CDM + $N_\mathrm{eff}$ + $\sum m_\nu$ + $T_\mathrm{AGN}$ + $A_\mathrm{kSZ}$ + $n_\mathrm{kSZ}$ model by less than 7%. The small impact on cosmological parameters reflects the strong constraining power of CMB polarization, the temperature-polarization cross spectra, and CMB lensing spectra reconstructed from polarization-only estimators, all of which are minimally affected by extragalactic foregrounds. In particular, the survey remains a sensitive probe of light thermal relic particles, achieving $\sigma(N_\mathrm{eff}) = 0.0154$, which can exclude any new species ($\Delta N_\mathrm{eff} \ge 0.027$) with at least 90% confidence. Our simulation and foreground-removal codes are publicly available and should aid the development of analysis pipelines for ultradeep, ultrahigh-resolution microwave surveys.

Kehle and Unger have recently shown that, under suitable conditions, a massless charged classical scalar field can produce an extremal black hole in finite time. This result appears to violate the third law of thermodynamics (TLT), since extremal black holes have zero temperature. However, because the TLT is intrinsically a quantum principle, a self-consistent analysis of this problem must account for quantum effects. In particular, we point out that the electric field of the system may spontaneously polarize the vacuum, thereby creating massless charged pairs that will discharge the black hole. This mechanism guarantees the quantum validity of the TLT in the regime $|eQ|\geq\hbar/2$ (here ${Q,e}$ denote, respectively, the electric charges of the black hole and the scalar field). This leaves open the question of what happens for lower values of $|eQ|/\hbar$. Recently, Schneider derived a classical bound showing that extremal black holes cannot be formed à la Kehle-Unger in the small-charge regime $|eQ|\leq\hbar/3$. His analysis leaves open the possibility that a stronger bound may exist. We conjecture here that this bound can indeed be strengthened such that classical considerations would prevent extremal (zero-temperature) charged Reissner-Nordström black holes from forming dynamically in the regime $|eQ|<\hbar/2$, where quantum polarization effects are too weak to preserve the validity of the TLT.

A sufficiently strong hadron-to-quark first-order phase transition can give rise to a third family of stable compact stars that are commonly referred to as hybrid hadron-quark stars. Stable hybrid stars that have the same gravitational mass as neutron stars are referred to as twin stars. Although equilibrium twin stars may exist, whether they can be dynamically formed remains an open question. We investigate this problem by examining the gravitational binding energy of competing equilibrium configurations at fixed baryonic rest mass and by performing general relativistic hydrodynamical simulations of several possible transition channels. While twin stars are more gravitationally bound than neutron stars with the same rest mass, this energetic preference alone does not determine the dynamical outcome. Compression and shocks during the evolution generate thermal pressure that can prevent the system from settling on the cold twin star branch. Our simulations show that sufficiently rapid cooling can remove this thermal support and enable twin star formation, whereas slower or no cooling generally favors a neutron star remnant. Accessing the twin star branch through the formation channels considered here requires cooling on a timescale comparable to or shorter than the stellar dynamical timescale. Since realistic cooling mechanisms operate on much longer timescales, our results suggest that in channels that conserve the total rest-mass neutron stars may be dynamically favored even when a more gravitationally bound twin star configuration exists with the same rest mass. Our results demonstrate a point of principle, at least for equations of state where the quark deconfinement density does not change appreciably for temperatures up to $10-20\,\textrm{MeV}.$

Recent advances in quantum hardware relax the strict geometric-locality constraints traditionally imposed on quantum error-correcting codes, motivating interest in high-rate quantum low-density parity-check (qLDPC) codes. At the same time, color codes provide a particularly rich setting for fault-tolerant quantum computation, underlying protocols such as single-shot error correction and self-correcting quantum computation. Hyperbolic color codes provide a class of high-rate qLDPC codes that also retain the structural features of color codes relevant to fault-tolerant quantum computation. However, previous constructions of hyperbolic color codes have achieved at most logarithmic code distance. In this work, we construct hyperbolic color codes with both constant rate and polynomial distance by building on arithmetic hyperbolic manifolds that support polynomial-distance hyperbolic toric codes. Our construction applies in arbitrary dimension \(D\geq 4\). In even dimensions, the resulting type-\(D/2\) color codes have constant encoding rate and polynomial distance, while in other cases the number of logical qubits and the code distance both exhibit polynomial scaling. We further derive explicit exponents for polynomial lower bounds as functions of the dimension and code type. These results establish a family of hyperbolic color codes simultaneously achieving constant rate and polynomial distance and providing a testbed to explore fault-tolerant quantum computation protocols that combine high-rate quantum codes with the structural advantages of color codes.

We address the question of whether topological metals (TM) retain their nontrivial characteristics in the presence of disorder. While in the clean case, the issue is what protects the gaplessness of the spectrum, i.e. the band-touching nodes in TM, this question needs to be reformulated in the presence of disorder. The concept of gaplessness loses its sharp meaning in this case, since spectral gaps can be filled in by disorder-induced states. What is still meaningful is entanglement: one may ask whether the long-range entanglement of the clean gapless TM survives in the presence of disorder or, in other words, whether nontrivial topology protects the TM from Anderson localization. We demonstrate that such a protection exists in the case of three-dimensional (3D) Weyl semimetals, but not in 2D and 3D (type-I) Dirac or 3D nodal line semimetals. We establish this by combining the idea of unquantized anomaly as the topological response of TM with the decorated domain wall construction, used previously to discuss average symmetry-protected topological insulating phases.

We study baryon $(\mathcal{B})$ formation in the early Universe in a confining $SU(\mathcal{N})$ gauge theory with quarks transforming in the fundamental representation. Casimir scaling of the confining potential implies that, at large $\mathcal{N}$, $\mathcal{B}$ formation is hindered by a bottleneck: for small quark clusters, representing the initial stages of $\mathcal{B}$ assembly, destruction processes greatly outweigh formation processes. In a $\mathcal{B}$-$\bar{\mathcal{B}}$ symmetric plasma, the relic density of cosmologically stable $\mathcal{B}$'s is set, for large $\mathcal{N}$, during confinement rather than by annihilation freeze-out. This affects relic-density estimates for $SU(\mathcal{N})$ dark matter models.

The "Little red dots" (LRDs) are a population of accreting supermassive black holes (SMBHs) in the early Universe which often exhibit undermassive or even undetectable stellar hosts. Their early emergence, high space density, and extremely large black-hole-to-stellar mass ratios pose a serious challenge to conventional seeding scenarios that rely on baryon for both the formation and growth of black holes. Here we demonstrate that the above anomalies can be naturally resolved if dark matter is self-interacting. We apply a fully relativistic, non-equilibrium halo-evolution model, first developed in our earlier work, to trace the complete gravothermal evolution of self-interacting dark matter (SIDM) halos, from the initial collapse into BH seeds to the subsequent accretion of dark matter. We find that in highly concentrated halos assembled before reionization, gravothermal collapse efficiently produces stellar-mass black-hole seeds within a few hundred million years. Remarkably, and contrary to standard expectations for dark-matter accretion, heat conduction in SIDM then sustains a prolonged super-Bondi inflow that drives these seeds to supermassive scale by the LRD epoch, without baryonic assistance. The halo conditions required for completing these processes, together with the probability of avoiding major mergers that disrupt gravothermal evolution, result in an SMBH population consistent with the observed abundance and redshift distribution of LRDs. Our findings establish a pathway in which SMBHs are seeded and assembled primarily from dark matter, well before substantial galaxies form around them, thereby offering both a compelling physical explanation for LRDs and a new observational probe of dark-matter microphysics.

At the heart of every atomic clock is a quantum coherent emitter, the laser, that could in principle be treated autonomously. While their frequency or phase stability is typically studied in the semiclassical regime of a large number of emitted quanta, recent works on autonomous quantum clocks suggest that the few-quanta regime can offer statistical information in the temporal domain. This provides complementary means to probe the fundamental limits to precise timekeeping in the quantum regime. Motivated by these works, we consider simple models for two- and three-level quantum emitters subject to an athermal fueling through dephasing, which generically results in coherences in the steady state. A large deviation principle with finite-time contributions is used to identify the transient counting statistics and their dependence on the initial conditions. We conclude by discussing the implications for precise timekeeping and quantum sensing using autonomous quantum emitters as clocks in their transient regime.

We introduce a model of dark matter charged under a new confining gauge group akin to the Standard Model's quantum chromodynamics (QCD). The fermionic sector contains both heavy and light quark-like fermions charged under the dark QCD. As the Universe cools, the gauge force confines and dark radiation transitions from free particles to low-mass dark pions. This form of dark radiation behaves as an imperfect fluid with nonzero viscosity. If the confinement occurs at the MeV scale, the model can alleviate the tension between early- and late-time measurements of the Hubble parameter, with a Bayesian posterior of $H_0 = 71.60\pm 0.63$ km/s/Mpc and a $3\sigma$ residual tension across Planck, ACT, BBN, Pantheon+, DESI DR2, and SH0ES. In the late Universe, the heavy dark matter can evade existing constraints on dark matter self-interactions while containing a rich phenomenology that may be accessible in future observations.

Motivated by searches for weak coherent drives, we formulate repeated quantum sensing with a fixed shot budget as an asymmetric composite hypothesis test. Taking Rabi sensing as a concrete example, we benchmark detection power, sensitivity, and Type-II error exponents in the resonant case with unknown signal amplitude and phase. We compare non-adaptive population and transverse readouts with a myopic Bayesian policy that selects each projective axis by maximizing the expected information gain in one step. The common decision statistic is a log Bayes factor, with a policy specific threshold calibrated under the null to enforce a common Type-I error. A weak signal expansion shows that population readout is phase independent but quadratic in amplitude, giving $n^{-1/4}$ sensitivity, whereas transverse readout is linear in amplitude and permits $n^{-1/2}$ sensitivity without adaptation, but is phase-dependent. In Monte Carlo pseudoexperiments, the adaptive policy exploits posterior information about the unknown direction to guide subsequent readouts; its sensitivity is consistent with $n^{-1/2}$ over the simulated large $n$ range and, at the largest simulated shot counts, outperforms the fixed transverse schedules. Its phase-averaged effective Type-II exponent also exceeds the non-adaptive references over the simulated range. These results demonstrate the finite budget value of exploiting nuisance parameter information under calibrated false positive control.

We develop a new framework in which eclectic groups are realised as flavour symmetries without flavons. Focusing on the group $\Omega(1)$, we show that it can be realised as a finite image of the integral Jacobi group, i.e. the semidirect product of $H({\mathbb Z})$ with $SL(2,{\mathbb Z})$, acting on two moduli $(\tau,z)$. The Heisenberg subgroup $H({\mathbb Z})$ leaves the modulus $\tau$ unchanged, and its finite image $\Delta(27)$ plays the role of the traditional flavour symmetry. We provide the ingredients needed to construct supersymmetric Jacobi-invariant theories, both in globally supersymmetric theories and in supergravity. We develop a realistic model of fermion masses within this framework and formulate a consistent CP symmetry, which can be imposed at the Lagrangian level and broken spontaneously by the moduli. We discuss how the conventional eclectic-flavour description is recovered in an appropriate limit. We also extend this geometric interpretation to the $T^2/\mathbb Z_4$ and $T^2/\mathbb Z_2$ eclectic building blocks, and clarify why the $T^2/\mathbb Z_6$ case is structurally different.

Non-perturbative scalar potentials are a central ingredient for stabilising moduli in flux compactifications. A key target in this context is the direct 10d derivation of the LVS AdS potential, i.e., the scalar potential of the Large Volume Scenario before the uplift. The familiar result, relying on 4d supergravity machinery and large volume expansion, consists of three terms of parametric form $\exp(-2a\tau_s)/{\mathcal V}$, $W_0\exp(-a\tau_s)/{\mathcal V}^2$, and $W_0^2/{\mathcal V}^3$. In plain 10d EFT language, the first term is an instanton-anti-instanton effect while the second term comes from a single instanton coupled to 3-form flux. When attempting to derive the suppression by the volume ${\mathcal V}$ directly from the 10d EFT, one encounters a puzzle: One expects a flux-dilution factor $1/\sqrt{\mathcal V}$ for the second term and a factor $1/{\mathcal V}^2$ from Weyl rescaling to the 4d Einstein frame for both the first and second term. Thus, the total volume suppression for these two terms is stronger than in the aforementioned 4d EFT expectations. We discuss the underlying logic in detail, also in the gaugino condensation case, but fail to find a satisfactory explanation for the mismatch. While log-corrections to the Kähler potential may be responsible, these would have to be strong enough to affect the outcome of the LVS scheme at the ${\mathcal O}(1)$ level. What is worse, the origin of the required correction remains unclear.

Gravitational sums over spacetime topology suggest a baby-universe field theory whose quanta are entire universes. We develop such a description from group-averaged amplitudes that impose gravitational constraints and define physical inner products in the single-universe theory. To sharpen the contrast with ordinary QFT, we start with gravity on one-dimensional worldlines, which can arise from reducing higher-dimensional cylinders. For multiple noninteracting worldlines that pair boundary components, the baby-universe Hilbert space is the symmetric Fock space over the physical one-universe Hilbert space, and the universe field expands in the on-shell modes spanning the latter. Each mode multiplies the sum of creation and annihilation operators, so the mode coefficients commute. The mode expansion thus makes explicit the field's commutativity and its Wheeler-DeWitt linear field equation. Diagonalizing the coefficients recovers a statistical description by a Gaussian path integral over on-shell field configurations labelling superselection ($\alpha$-)sectors. We take exploratory steps toward more general topologies. Disk-like topologies coherently shift the no-boundary state, turning on the Hartle-Hawking wavefunction as a one-point function. Even with nontrivial topologies represented by interacting Feynman diagrams, we argue that group averaging near each boundary still enforces the same linear field equation, while interactions instead enter through a non-Gaussian measure over $\alpha$-sectors. In the topological Marolf-Maxfield model, we promote a disk-and-cylinder truncation to an exact Fock-space representation of the full theory incorporating all topologies. We also relate the truncated and exact inner products by an insertion of interactions, whose perturbative expansion produces a sum over time evolutions generated by pairs of pants, evoking an analogy to group averaging.

Hot-Jupiters, gas giant planets with equilibrium temperatures above 1,000 K, host large temperature gradients between their permanent day- and nightsides, resulting in circulation regimes that have no Solar System analogs. Past Kepler and Spitzer measurements show that the phase curves of these objects typically peak westward of the substellar point at optical wavelengths and eastward in the infrared, indicative of an interaction between circulation and cloud coverage. However, few hot-Jupiters have joint reflected light and thermal emission measurements, preventing a definitive statement as to the link between these phenomena. Here, we present the first phase curve of a hot-Jupiter that separates thermal emission and reflected light through JWST observations of NGTS-10 Ab with the NIRSpec PRISM instrument ($\lambda$=0.5-5.5 $\mu$m). Using the spectrally-resolved phase curve, we jointly retrieve the planet's thermal and reflected light maps. We show that the temperature and reflectance distributions are anti-correlated, best explained by clouds evaporating from the eastern substellar region ($\varphi\approx$-17 to 48$^\circ$) where temperatures are highest. This is confirmed by comparisons of the phase-resolved spectra with three-dimensional circulation models, which show that NGTS-10 Ab's atmosphere hosts inhomogeneous cloud coverage, likely made-up of $\mu$m-sized silicate particles, and weak atmospheric drag ($\tau_\mathrm{drag}\gt 10^6$ s). Finally, by measuring the spectral variation of the thermal phase curve offsets, we infer a slope of 7.1$\pm$1.9 degrees per pressure dex, indicative of heat transport that becomes more efficient at depth. Future optical and infrared hot-Jupiter phase curve measurements over a wide range of equilibrium temperatures will enable a complete mapping of the interplay between heat transport and cloud formation in highly-irradiated exoplanet atmospheres.

Recent progress in collider physics has reformulated phenomenological questions in terms of detector correlation functions and advanced their theoretical understanding. These advances have primarily focused on correlators of the average null energy operator, $\mathcal{E}(\vec{n})$, known as energy correlators. However, colliders have access to a much broader class of detector operators, $\mathcal{E}^n_R(\vec{n})$, which measure powers of the energy on a subset of hadrons $R$, such as charged hadrons. These generalized detectors are generically not infrared and collinear safe, and their description requires nonperturbative matching between the hadronic detectors measured in the infrared and the partonic detectors used in ultraviolet calculations. We develop a framework for computing their multi-point correlation functions. We introduce universal nonperturbative matching coefficients, termed "detector functions", that implement this infrared-ultraviolet matching. For the $\mathcal{E}_R^n$ operators studied here, these coefficients are represented by energy-weighted moments of single- and multi-hadron fragmentation functions. We present their renormalization group structure, derive QCD factorization theorems for the projected correlators, and compute jet functions through next-to-leading order. In the fixed-coupling pure Yang-Mills limit, we derive the light-ray OPE of hadronic detectors and connect it to the QCD factorization framework. We also identify universal nonperturbative power corrections generated by soft radiation, which are enhanced in the collinear limit and can substantially modify the perturbative angular scaling. A parton shower study finds qualitative agreement with the predicted perturbative and nonperturbative scaling behaviors. Our work significantly broadens the space of detector operators under theoretical control, with potential phenomenological applications.

We find the necessary and sufficient conditions for the gravitational path integral (GPI) to admit an interpretation in terms of (i) an inner product in the Hilbert space of open/closed universes or (ii) a statistical average of boundary observables. The conditions needed for (i) are necessary but not sufficient for (ii). Requiring the stronger condition (ii) places additional constraints on all wormhole amplitudes, giving a concrete diagnostic of whether the GPI computes an average or merely a pseudo-average. To exemplify the difference between the two constraints, we present a class of gravitational toy models that satisfy (i) but fail the stronger condition (ii); to emphasize the power of the stronger condition, we initiate a bootstrap study of statistical ensembles based on condition (ii), finding that the resulting constraints substantially sharpen the bounds on the moments of the ensemble obtained by imposing (i). More broadly, both of these positivity conditions impose nontrivial constraints on wormhole amplitudes and thereby restrict which gravitational effective field theories can be embedded in consistent theories of quantum gravity.

We completely classify unitary 2d CFTs with central charge $c=1$ and discrete spectrum. We confirm the folklore that the only such theories are the compact free boson, its $\mathbb{Z}_2$-orbifold, and three exceptional theories obtained as orbifolds of the SU(2)$_1$ WZW model. The proof is by recasting the $c=1$ modular bootstrap as a crystalline measure problem for the density of states, and analytically solving it. We also show that, once the density of states is specified, the full CFT can be uniquely reconstructed.

We address the axion quality/cosmology tension that often plagues QCD axion models in post-inflationary Peccei-Quinn (PQ) breaking scenarios. In the proposed framework, the PQ symmetry emerges accidentally from an ${\rm SU}(\mathcal{N})_L\times{\rm SU}(\mathcal{N})_R$ gauge symmetry spontaneously broken to ${\rm SU}(\mathcal{N})_{L+R}$, and its quality is protected because PQ breaking first appears at operator dimension $\mathcal{N}$. Moreover, the construction avoids the domain-wall problem, ensures that no stable fractionally charged relic survives ${\rm SU} (\mathcal{N})_{L+R}$ confinement, and remains free of Landau poles below the scale of PQ-breaking operators. The exotic quarks required to generate the PQ anomaly hadronize into unstable mesons and cosmologically stable neutral baryons. However, plausible arguments indicating a strong suppression of baryon formation in ${\rm SU}(\mathcal{N})$ gauge theories at large $\mathcal{N}$, suggest that their contribution to the dark matter energy density remains subdominant. Combining cosmological constraints with PQ quality and perturbativity requirements yields a viable parameter space in which the axion makes up most of the dark matter and its mass remains predictable.

What is the boundary dual of an Unruh-DeWitt detector in anti-de Sitter space? We argue that this question is naturally answered by the HKLL reconstruction program. A local detector in the bulk can be associated with a smeared detector in the boundary, where the choice of smearing depends on the choice of HKLL kernel. We use this formalism to analyze entanglement harvesting in the Poincaré patch of AdS$_{3}$ for a bulk Unruh-DeWitt detector paired either with a boundary detector or with a second bulk detector. We compute the amount of harvesting in the standard way, namely by evaluating the two-detector density matrix to quadratic order in the coupling $\lambda$. Additionally, we address an apparent tension between microcausality for spacelike-separated bulk detectors and the fact that the dual HKLL detectors may directly overlap in the boundary theory.

A quantum many-body system coupled to an environment relaxes to a nonequilibrium steady state that can sustain order with no equilibrium counterpart. Computing such steady states is harder than closed-system dynamics as the density matrix problem squares the Hilbert-space dimension, and no free energy selects the steady state. The dissipative spin-1/2 Heisenberg chain is a benchmark example for nonequilibrium steady state physics; various methods have each calculated its phase diagram but do not agree, and a controlled determination at large system size has remained out of reach. Here we simulate the Lindblad dynamics of chains of up to 50 sites on the superconducting processor ibm_kingston – 100 simultaneously active qubits at up to 1700 entangling-gate depths – realizing the dissipation via Stinespring dilation. The system's dissipative evolution is a self-correcting mechanism that effectively erases errors, so hardware noise enters only as a weak competing dissipator. We measure static structure factors and resolve ferromagnetic, antiferromagnetic, spin-density-wave, and paramagnetic steady states, mapping the phase diagram with 117 quantum hardware data points across the $J_x$–$J_y$ plane. We uncover a rich non-equilibrium phase diagram of ordered phases with only remnants of the mean-field order, and where sharp transitions give way to the crossovers expected in one dimension. We also find the existence of an incipient (Trotter-induced) spin density wave phase, highlighting the potential of controlled Trotterization as a tool to engineer various magnetic phases in dissipative spin systems. Our quantum simulations largely settle the lingering uncertainty regarding the correct phase diagram of this benchmark system. Moreover, they show that quantum computers are now a feasible tool for addressing scientific questions involving dissipative quantum systems.

We follow a $D$-module approach to the construction of canonical differential equations for Feynman integrals directly from their Gel'fand-Kapranov-Zelevinsky (GKZ) hypergeometric systems. Starting from the Schwinger representation, we identify the associated generalized Euler integral and its GKZ system, as an alternative to the Lee-Pomeransky representation. The generalized Euler formulation allows reductions associated with facets of the Newton polytope to be identified directly, reducing the number of variables in the resulting differential systems. We construct the associated Pfaffian systems using Frobenius bases, which also provide direct access to the singular loci. After a suitable rationalizing change of variables, the systems are brought into canonical $\epsilon$-form. A key feature of the construction is that the dimension of the canonical basis is determined by the holonomic rank of the GKZ system and, for the examples considered, it is smaller than or equal to the number of master integrals obtained from integration-by-parts, thus providing a reduced description of the differential system.

The nitrogen-vacancy (NV) center in diamond is a prominent quantum-sensing platform. Combining readout at the quantum projection noise limit with strong dipolar interactions promises substantial gains in sensitivity. However, experimentally accessing this regime has remained a longstanding challenge. In this work, we demonstrate quantum-projection-noise-resolved readout of a strongly-interacting, two-dimensional ensemble of NV centers. Our approach leverages repetitive readout via the NV's intrinsic $^{15}$N nuclear memory at a moderate magnetic field ($\sim 0.3$ T), improving the readout fidelities by nearly an order of magnitude. This enables us to directly resolve the quantum projection noise of a coherent spin state and to watch the ensemble's intrinsic dipolar interactions shear this noise into an anisotropic profile. Our results open the door to direct measurements of spin squeezing and entanglement-enhanced sensing in the solid state.

Discrete-Modulated (DM) Continuous-Variable (CV) Quantum Key Distribution (QKD) is an experimentally attractive approach to quantum cryptography, offering high key rates over metropolitan-scale distances while relying on state-of-the-art telecom infrastructure. However, a fundamental gap has remained between this experimental promise and rigorous security: for more than two decades, DM CV-QKD has lacked a complete composable finite-size security proof against coherent attacks. Existing works either restrict the adversary to collective attacks, impose additional finite-dimensional assumptions, apply only to specific modulation formats, or fail to recover the known asymptotic rates. Here, we resolve this longstanding problem by establishing the first complete composable finite-size security proof for DM CV-QKD protocols against coherent attacks, incorporating imperfect detectors and both fixed- and variable-length protocol variants. Our proof introduces two central results of broader interest: an infinite-dimensional marginal-constrained entropy accumulation theorem (iMEAT) and a rigorous dimension-reduction technique that makes the infinite-dimensional security bounds numerically tractable. The resulting key rates recover the known asymptotic rates and outperform established finite-size bounds based on collective attacks, while yielding positive key rates beyond $70$km for experimentally relevant block sizes and parameters. Thus, our work closes a longstanding gap and places an experimentally attractive class of CV-QKD protocols on a rigorous composable security footing and provides a pathway towards their practical deployment.

Experimental searches for GeV-scale feebly interacting particles commonly target the simplest decay signatures with two charged particles, including hadrons. Hadronic modes often dominate the inclusive decay rate, and their simulation relies extensively on Pythia. Its fragmentation model, calibrated mainly on LEP data, is unreliable in this mass range: it populates symmetry-forbidden states and misidentifies the dominant allowed channels. We construct a simple hadronization model tuned to electromagnetic scattering data and constrained by conservation laws and available exclusive decay calculations, while retaining a common prescription applicable to different particle models. Considering the SHiP experiment as an example, we show that our model shifts the dominant search signature after event selection from two-particle to multiparticle decays, including mixed charged-neutral states. We provide the model in a form that can be readily integrated into Pythia-based experimental simulation frameworks.

Massive spin 2 fields on de Sitter must satisfy the Higuchi bound, $m^2\geq 2H^2$. Compactifications of higher dimensional gravity to $\mathrm{dS}_4$ come with a tower of Kaluza-Klein gravitons whose masses are fixed by the internal geometry, so the bound becomes a constraint on the compactification. We propose that the KK gravitons of a consistent compactification never violate it, and test this in a few examples. On a circle stabilized by Casimir energy the bound holds unless the circle shrinks below the species scale, and on a warped interval with negative tension branes the tower is gapped at $m^2\geq \tfrac{9}{4}H^2$ for any length of the interval. On group manifolds, we argue that if the internal curvature is not parametrically larger than the Hubble scale, the bound can apparently be violated by smooth deformations. The violation disappears once one promotes these deformations to moduli, which are immediately extremized when solving the 10d equations of motion.