Papers

We show that for a CFT$_D$ on a flat open solid torus, the two point function in the Weyl frame is exactly paired with a finite geodesic lying entirely in the AdS$_{D+1}$ bulk interior. This relation is exact and requires neither large $N$, strong coupling, nor heavy operators. The exactness is that of conformal kinematics; no semiclassical bulk dynamics is assumed. The standard boundary-anchored relation is a singular limit of the exact pair. For the free scalar, a mode expansion along $S^1$ generates an infinite tower of effective masses on $H_{D-1}$, whose intricate propagators resum exactly to the same simple higher-dimensional geodesic expression. Together with another exact pair between disjoint entanglement entropy and entanglement wedge cross-section found on the same open solid torus, this result points toward a broader exact-pair program in AdS/CFT.

We investigate the dynamical critical behaviour of black hole phase transitions in anti de Sitter spacetime by extending the stochastic framework of free energy landscape dynamics to Kerr AdS black holes. By analyzing the Langevin evolution of the entropy (in contrast to the horizon radius in the RN-AdS case) near criticality, we demonstrate that the system exhibits pronounced critical slowing down, characterized by a significant increase of the autocorrelation time as the critical point is approached. This behaviour is further confirmed by the lowest eigenvalue of the Fokker-Planck equation. By analysing the dynamics along different thermodynamic paths, including variations in temperature, pressure, and angular momentum, and considering both directions - towards and away from criticality, we find that the relaxation time obeys a robust scaling relation, $\tau=|\epsilon|^{-2/3}$ near criticality. The same scaling exponent is obtained for RN-AdS, Kerr-AdS, and Bardeen black holes, suggesting the existence of an underlying universal dynamical behaviour across distinct black hole systems. Our results establish a connection between the geometry of the free energy landscape, stochastic nonequilibrium dynamics, and universal critical phenomena in black hole thermodynamics.

Charge-dependent scalarization of the Einstein-Euler-Heisenberg (EEH) black hole is carried out in the EEH-scalar theory by introducing an exponential scalar coupling with coupling constant $\alpha$ to the Maxwell and nonlinear electrodynamic terms. The bald black hole (EEHBH) is described by mass $M$ and arbitrary magnetic charge $q$ and has a single horizon when choosing the action parameter $\mu=0.3$. Here, we find the critical onset charge $q_c=r_+^2/\sqrt{2\mu}$ with $r_+(M,q_c)$ the outer horizon radius from the resonance condition. The spontaneous scalarization ($\alpha^+$) of this black hole is available for charge $0<q< q_c=1.115$ for $M=1$ and $\mu=0.3$, with positive $\alpha$, whereas its new scalarization ($\alpha^-$) occurs for $q> q_c$ and negative $\alpha$. The former case of $q=0.5$ implies infinite branches of scalarized EEHBHs but its fundamental branch ($n=0$) is stable against the $l=0$ modes considered here, while for $q=2$ and $q=20$, one stable scalarized branch is found for each charge within the explored parameter ranges.

We investigate the impact of braneworld theory on the astrophysical environment surrounding a black hole. The black hole is sourced by localized matter from the bulk, which could describe both regular and singular (Schwarzschild) black hole. Employing an Einstein cluster description for the environment, we find that the anisotropic nature of the cluster, coupled with finite brane tension, leads to a weakening of gravity due to the quadratic and nonlocal corrections to the effective four-dimensional field equations. Consequently, this effect prevents horizon formation within the environment. Applying current constraints on the brane tension derived from neutron star observations, we demonstrate that this effect is particularly relevant for sub-stellar mass black holes embedded in compact environments. Furthermore, we investigate the optical signatures of finite brane tension in this scenario, specifically focusing on the black hole shadow and Einstein ring radii. We show that the Einstein ring radius decreases with a smaller brane tension, whereas the black hole shadow radius increases–somewhat contradicts the weakening gravity effects. Ultimately, these two observables may jointly serve to constrain the value of the brane tension in a very specific astrophysical scenarios.

We study the thermodynamic and statistical properties of a gas governed by a multifractional modified dispersion relation of the form $\omega^{2}=k^{2}+4E_{*}^{-1/2}k^{5/2}$, where $E_{*}$ sets the characteristic scale of the multifractional correction. Working within the grand-canonical ensemble, we derive the modified density of states, the grand potential, the partition function, and the main thermodynamic quantities for both bosonic and fermionic sectors. The deformation changes the available phase-space distribution and produces nonstandard thermal scalings controlled by the ratio $T/E_{*}$. In the infrared regime, the usual relativistic gas behavior is recovered with leading corrections proportional to powers of $(T/E_{*})^{1/2}$. In the ultraviolet regime, the density of states scales as $\varrho(\omega)\propto \omega^{7/5}$, corresponding to an effective density-of-states dimension $d_{\mathrm{eff}}=12/5$. As a consequence, the Stefan-Boltzmann law is deformed from $u\propto T^{4}$ to $u\propto E_{*}^{3/5}T^{17/5}$, while the equation-of-state parameter approaches $w=5/12$ instead of the standard radiation value $w=1/3$. We also analyze thermal stability, particle number and energy fluctuations, Bose-Einstein condensation, and the degenerate Fermi gas limit. The multifractional correction increases the critical temperature of a conserved bosonic gas and modifies the Fermi energy, pressure, sound speed, and low-temperature heat capacity of degenerate fermions. A direct fit to the COBE/FIRAS monopole spectrum yields $E_{*}>0.36\,\mathrm{MeV}$ at $95\%$ CL, while the conservative GWTC–3 propagation constraint gives $E_{*}>1.18\times10^{19}\,\mathrm{GeV}$ at $90\%$ credibility when the dispersion relation is assumed to be universal.

We point out that some works on higher-derivative corrections in the AdS/CFT duality use inappropriate "AdS/CFT dictionary." We illustrate the problem using a class of holographic superconductors in the Gauss-Bonnet black hole background. We also point out another problem in previous works. These modifications can change the qualitative behavior of physical quantities such as the spontaneous condensate. Whether the condensate increases or decreases under higher-derivative corrections depends on the system one considers, and there is no universality in this sense.

We introduce a new series decomposition of the waveform constructed in the spirit of Debye expansions in scattering theory, and we use this to analyse the time-domain response of compact, horizonless bodies to scalar-field perturbations on curved spacetimes. The Debye decomposition separates out direct exterior propagation, surface reflection, and successive transmissions through the interior of a compact body, and it provides an intuitive interpretation of the waveform in terms of geodesic trajectories. By analysing the quasinormal-mode (QNM) content of individual Debye terms, we set out a Debye-QNM description that is complementary to the standard QNM description. With this framework, we examine a scalar field propagating on two illustrative `Schwarzschild star' compact-body spacetimes: a neutron-star-like model \(R>3M\) and an ultracompact object \(R<3M\). We show that the Debye reconstruction matches well with the exact waveform, and that (unlike the standard QNM reconstruction) it converges even at early times, giving an accurate description of all waveform features including the prompt response. In the neutron-star case, the low-order Debye terms mainly describe the ringdown and a non-modal component associated with the sub-threshold branch cut. In the ultracompact case, the Debye series organizes the waveform into a prompt/ringdown contribution followed by a succession of individually resolved echo-like wavepackets. The new Debye-QNM expansion and the standard QNM expansion have complementary spectral interpretations: the former identifies modes in individual propagation channels, whereas the latter describes collective resonances that are resummations of the former. This distinction clarifies how echo-like structures emerge from repeated interior propagation, and how pole and branch-cut contributions enter the time-domain signal.

We construct coherent states for the quantized electromagnetic field that correspond to the classical non-null torus knot solutions of Maxwell's equations in vacuum. We derive the displacement operators from the general relation between classical fields and coherent state amplitudes and verify the defining properties of coherent states through direct computation. We determine the observables of the model: field expectation values, energy density, Poynting vector, helicity, photon number, quadrature uncertainties, and correlation functions, and calculate their expectation values in the knotted coherent states in terms of the integer parameters $(n,m,l,s)$ of the classical solutions. As an example, we particularize the construction in the case of the Hopfion coherent state. These results establish the quantum-classical correspondence for this type of vacuum topological electromagnetic systems.

To ensure anomaly cancellation the $E_6$ inspired $U(1)$ extensions of the minimal supersymmetric (SUSY) standard model (MSSM) involve extra exotic matter. The lightest exotic neutralino in these models can be stable contributing to the cold dark matter density. We consider the interactions of such neutralino with nucleons within a specific extension of the MSSM with an additional $U(1)_N$ gauge symmetry (SE$_6$SSM). The constraints on the couplings of this state, which are set by the present experimental bounds caused by the direct detection experiments, are examined. The obtained results can be generalised to other $E_6$ inspired SUSY models with extra $U(1)$ gauge symmetry.

We study a symmetry-reduced sector of $AdS_3$ gravity formulated as an $SO(2,2)$ Chern–Simons theory on a three-dimensional manifold with toroidal boundary. The reduction is implemented by requiring a global symmetry and restricting to the sector where the gauge connection is invariant along the symmetry flow. The resulting theory reduces to a two-dimensional BF-like model together with an induced one-dimensional boundary action, whose form is fixed by the three-dimensional Chern–Simons origin. On the boundary subspace selected by suitable mixed boundary conditions, the one-dimensional action reproduces the standard Drinfel'd–Sokolov restriction to coadjoint orbits of the Virasoro group, among them the Schwarzian dynamics associated with JT gravity. Moreover, the $\mathfrak{so}(2,2)$ algebra of the three-dimensional Chern–Simons model naturally generates current-dressed Kac–Moody extensions of the one-dimensional boundary dynamics. The full one dimensional boundary dynamics of the reduced theory is then shown to be compatible SYK-like tensor models with global symmetries.

Predictions for observables involving the cosmological 21-cm background require calculations of spatial correlations of star formation rate densities (SFRDs) which have a nonlinear dependence on the baryon-dark matter relative velocity. Prior work derived these SFRD correlations with a simplifying assumption that neglected the difference between the correlations of the components of the velocity parallel and perpendicular to the separation between the two points being correlated. Here we calculate the full joint PDF of the squares of the peculiar velocity at two different points. The error that arises in predictions for 21-cm fluctuations if this subtlety is overlooked is generally less than a few percent, but it can be larger for some values of wavenumber $k$ and redshift $z$ if there are cancellations between different contributions to the total signal. The correct expression is easily implemented and increases the run time of the code by only a few percent.

We study the topological properties of bordisms interpolating between different 9d gauged supergravities obtained from compactification of type IIB string theory on $\mathbb{S}^1$ with a non-trivial $\mathsf{SL}(2,\mathbb{Z})$ bundle. We describe how such bordisms implement the needed monodromies through stacks of $[p,q]$ 7-branes or gravitational solitons of non-trivial topology. For the later mechanism, we see that the topology of the bordism becomes increasingly complicated for large monodromies, which results in the associated bordisms being arbitrarily suppressed, against expectations on the breaking of global symmetries in Quantum Gravity. Motivated by this, we propose a refinement of the Swampland Cobordism Conjecture for the first bordism group $\Omega_1({\rm B}G)$ with a $G$ duality bundle. We argue that even if gravitational solitons can realize the monodromies associated with elements of the commutator subgroup of $G$, if the number of needed commutators is unbounded (in other words, the commutator width of $G$ diverges) then an infinite number of duality defects realizing elements in $G$ need to be included. We test this proposal for different duality groups $G$, and see that our expectations are realized, often in non-trivial ways.

We prove the Rényi quantum null energy condition for every integer Rényi order $n\geq2$. In local Poincaré-invariant quantum field theory, this states that the sandwiched Rényi divergence (SRD) of an excited state relative to the vacuum is convex along a future-directed null deformation. We assume that the deformation is realized by the canonical translations of a half-sided modular inclusion and that the divergence is finite for the initial, undeformed algebra. The proof establishes convexity of the SRD along the induced positive contraction semigroup on Haagerup $L^n(M)$, for every non-zero positive initial element. We also establish a Rényi ant formula at every even integer order and, under an additional regularity assumption, at odd integer orders. The Rényi ant formula identifies the negative first null derivative of SRD with a multiple of the infimum of the canonical null-translation energy over vector purifications of an escort state constructed from the excited state and the vacuum.

We construct rotating black holes in Carroll gravity using two distinct approaches. In one of them, we exploit the freedom in the Carroll compatible connection to encode rotation. In particular, we construct rotating solutions in magnetic Carroll gravity by dressing the Carroll-Schwarzschild black hole with a rotational charge. This solution is intrinsically Carrollian and has no Lorentzian analog. In the other approach, we construct an extension of magnetic Carroll gravity from general relativity in an odd-power expansion in the speed of light. This theory contains magnetic Carroll gravity as a subsector but has in general more physical degrees of freedom. We show that this theory admits a Carroll analog of the Kerr black hole as a solution, which we refer to as the "Kerroll black hole". Its rotation appears as an intrinsically odd-power effect in the Carroll data. We compute the corresponding conserved charges for both theories.

The present work is motivated by the statement that the Ising minimal model $\mathcal{M}(4,3)$ is equivalent, at the level of observables, to the $SU(2)_2$ Chern–Simons theory. At first glance, however, these two theories appear to differ substantially. For instance, the number of irreducible highest-weight representations does not match the number of Ising anyons. For tensor products of low degree, these discrepancies are examined in this work. While representation structure differs, it does not affect the observables underlying topological quantum computation algorithms.

We develop a framework in which Yukawa hierarchies arise from powers of fully anarchic spurions transforming in higher representations of the flavor symmetry group $SU(2)^{n_2}\times SU(3)^{n_3}$. The core mechanism is the progressive lifting of Yukawa ranks through successive outer products of composite doublets and triplets. We formulate the general construction in detail and build explicit models realizing it. We then investigate whether renormalizable scalar potentials for higher $SU(2)$ representations can dynamically generate anarchic spurions with non-vanishing composites. The framework predicts distinctive patterns in flavor-changing neutral currents and potentially observable stochastic gravitational-wave backgrounds.

We build a technique to generate rotation from arbitrary static solutions that asymptote to four- or five-dimensional Minkowski spacetime based on Clément's approach [1]. The method is purely algebraic and does not require solving Einstein equations. It proceeds by transforming the static solution to AdS$\times$S asymptotics, performing a coordinate shift to a uniformly rotating frame, and then transforming the solution back to asymptotically flat spacetime. We implement this construction in five-dimensional minimal supergravity, although it applies more broadly to any framework admitting AdS$\times$S geometries and relevant sigma-model transformations. As a first application, we recover simply the Kerr and Myers-Perry black holes directly from Schwarzschild black holes. We then apply the method to the linear class of static Weyl solutions and obtain the first linear ansatz describing an arbitrary number of non-extremal rotating and charged sources. This approach provides a systematic and simple route to constructing non-extremal rotating geometries in four and five dimensions.

We propose an infrared and asymptotic formulation of quantum gravity adapted to external observers. In an asymptotic proper-time gauge, the physical generator of evolution reduces to the Regge–Teitelboim boundary charge, so that quantum dynamics is governed by infrared gravitational configurations at spatial infinity. In the weak-field regime this leads naturally to a Born–Oppenheimer separation between slow asymptotic data and fast bulk fluctuations. Integrating out the latter induces a Berry connection on the space of admissible configurations, whose holonomy characterizes infrared-dressed gravitational states. Observable evolution is then governed by an infrared effective Hamiltonian obtained after integrating out fast bulk fluctuations, with the geometric (Berry) contribution entering as part of the resulting evolution operator on the space of asymptotic configurations. Tracing over unresolvable degrees of freedom induces a reduced density matrix whose entropy is dominated by global infrared holonomy sectors rather than local bulk dynamics.

Gravitational waves generated by violent processes in the early Universe necessarily couple to scalar perturbations beyond linear order. We show that tensor perturbations produced by first-order phase transitions and by annihilating domain-wall networks source density fluctuations at second order, thereby opening a distinct channel for primordial-black-hole (PBH) formation. We compute the tensor-induced density spectrum for both sources and map the resulting PBH abundance onto the macroscopic parameters $(\alpha,\beta/H,T_\star)$ of a first-order phase transition and $(\alpha_{\rm ann},V_{\rm bias},\sigma)$ of a domain-wall network. Existing PBH limits therefore impose complementary constraints on early-Universe sources of stochastic gravitational waves. We find viable regions where one can have an observable gravitational-wave background and an appreciable abundance of asteroid-mass PBHs, including benchmark points that saturate the dark-matter abundance. Our results establish a direct, testable correlation among the source scale, the gravitational-wave spectrum, and the PBH mass function, distinguishing this tensor-induced channel from PBHs formed through delayed vacuum decay or direct defect collapse. We also discuss viable particle physics origin of such FOPT and DW, and therefore, constraints on such microphysics, either in the visible, or in dark sector models.

We investigate realizations of (1+1)-dimensional fusion category symmetries on tensor-product Hilbert spaces, allowing for mixing with quantum cellular automata (QCAs). It was argued recently that any such realizable symmetry must be weakly integral. We develop a systematic analysis of QCA-refined realizations of fusion categories and prove two statements. First, we show that, under certain physical assumptions on defects, any QCA-refined realization has QCA and symmetry-operator indices determined by the categorical data, up to the freedom of redefining the symmetry operators. Second, we construct a lattice model that provides a QCA-refined realization for any weakly integral fusion category symmetry on a tensor product Hilbert space. We also compute indices of the QCAs in our lattice model and show agreement with the first result. As an application of the general construction, we give an explicit QCA-refined realization of general Tambara-Yamagami categorical symmetries.

A direct coupling between the inflaton and Standard Model gluons can dynamically raise the QCD confinement scale during inflation, making the axion temporarily heavy and suppressing axion isocurvature perturbations. As inflation proceeds, the confinement scale relaxes, the axion becomes light, and late-time de Sitter fluctuations can generate the observed dark matter abundance. We analyze this mechanism without specifying an inflationary potential, instead parametrizing the background by $\epsilon(N) \propto 1/N^p$, where $N$ is the number of $e$-folds before the end of inflation. The single parameter $p$ distinguishes monomial models ($p=1$), standard plateau models ($p=2$), and ultra-flat plateau or hilltop-like models ($p\ge 3$). We analytically show that the mechanism selects plateau-like ($p\ge 2$) inflation: monomial models generically cause the confinement scale to grow too rapidly, while plateau models keep the QCD sector under perturbative control. In the minimal scenario, reheating occurs through the same inflaton-gluon coupling, and viable axion dark matter production is obtained when deconfinement occurs after the CMB window. The early-confinement sector also generically shifts the scalar spectral index to smaller, redder values. Because ultra-flat ($p \ge 3$) models inherently predict overly red spectra, this shift exacerbates their tension with CMB data, leaving $p=2$ plateau models as the phenomenologically viable parameter space (in this parametrization).

The gravitational path integral produces an asymptotic expansion in $G_N$, a fact which is puzzling in the case of observables that are expected to fluctuate wildly. Wormholes appear to compute ensemble averages of functions of such observables, though in typical constructions of AdS/CFT, there are no parameters to average over except, in some examples, a single integer $N$. We introduce a procedure that we call “Mellin averaging” to define a sort of asymptotic average of a function of $N$. We argue that Mellin averaging over $N$ may suffice to reproduce the apparent randomness seen in wormhole physics, provided that the dual theory admits an analytic continuation in $N$ and the relevant observables fluctuate on superpolynomially small scales in $N$. As a test case, we consider the spectral form factor in the regime where the double cone is believed to dominate the gravitational path integral and compare to a random matrix theory in which $N$ behaves as a continuous variable. We also describe some toy models of analytic continuation in $N$: a qubit model that can be analytically continued in $N$, and an explicit construction of a deterministic function of $N$ that simulates a sequence of independent draws from a Gaussian ensemble.

Using the post-Newtonian effective field theory (PN-EFT) formalism for spinning gravitating bodies, we derive the next-to-leading-order (NLO) spin-orbit potential and Hamiltonian for a system of N spinning bodies in general relativity. This extends the EFT treatment of the binary case to arbitrary N. We present two derivations: one in the generalized canonical gauge, and one based on the covariant spin supplementary condition (SSC), followed by a noncanonical transformation to canonical variables. In both approaches, the only new contributions beyond the binary case are three-body interaction diagrams. The canonical Hamiltonians obtained from the two EFT routes agree with the known ADM N-body Hamiltonian of Hartung and Steinhoff up to a canonical transformation.

We show that the low-energy states of non-Abelian topological orders possess extensive magic which is long-ranged, and cannot be eliminated by a constant-depth local unitary circuit. This refines conventional notions of complexity beyond the linear circuit depth which is required to prepare any topological phase, and provides a new resource-theoretic characterization of topological orders. A central technical result is a no-go theorem establishing that stabilizer states–even up to constant-depth local unitarie–cannot approximate low-energy states of non-Abelian string-net models which satisfy the entanglement bootstrap axioms. Moreover, we show that stabilizer-realizable Abelian string-net phases have mutual braiding phases quantized by the on-site qudit dimension, and that any violation of this condition necessarily implies extensive long-range magic. Extending to higher spatial dimensions, we argue that any state obeying an entanglement area law and hosting excitations with nontrivial fusion spaces must exhibit extensive long-range magic. This applies, in particular, to ground-states and low-energy states of higher-dimensional quantum double models.

We point out that a simple late-time cosmological model where our Universe can absorb "baby universes" explains the exponential expansion of our universe without the need of a cosmological constant and leads to a z-dependence of the parameter w(z) in the equation of state. In this model w(z) is less than -1 for z sufficiently large.

In this paper, we investigate how AdS scalar propagators are represented in the celestial basis. Starting from the standard bulk-to-boundary propagator in Euclidean AdS space, we express the propagator in a Schwinger parametrization and construct the corresponding boundary-to-boundary propagator. We then transform the resulting propagators to the celestial basis using conformal primary wavefunctions for both massless and massive scalar fields. For the massless case, the celestial propagator reduces to an effectively two-dimensional boundary-to-boundary object on the celestial sphere dependent on the AdS/CFT conformal dimension $\Delta$ as a scaling factor. For the massive case, the celestial propagator exhibits a nontrivial kernel involving modified Bessel functions, closely resembling the momentum-space radial structure of AdS bulk-to-boundary propagators. The results suggest a structural translation from AdS propagators and celestial propagators.

We investigate a scalar-vector-tensor theory in which matter is minimally coupled to a Jordan-frame metric $\tilde g_{\mu\nu}=(1+\Xi)g_{\mu\nu}$, while a massive vector sector interacts with the baryonic current. We show that the conformal scalar coupling modifies the physical expansion rate measured by matter observers, leading to an enhancement of the Hubble constant inferred at low redshift. We stress, however, that the Hubble rate is not a conformal invariant, whereas the acoustic angular scale $\theta_s$ is, and we derive the exact integral condition that the scalar field evolution must satisfy. We show that a single-signed scalar velocity cannot satisfy it, and we construct instead a two-epoch phenomenological evolution which matches $\theta_s$ exactly while retaining the late-time enhancement, at the cost of a small pre-recombination shift of the effective gravitational coupling. Importantly, the recombination temperature is unmodified, since particle masses are constant in the Jordan frame, only the expansion rate at that epoch being altered. The scalar potential naturally acts as a dynamical dark-energy sector, while the vector sector provides two distinct contributions. The temporal component, determined algebraically by the baryon current, yields an apparent matter-like term in the background expansion that is not a true fluid but rather a manifestation of the interaction energy. The propagating spatial modes, on the other hand, form a vector condensate that behaves as a collisionless pressureless component and can play the cosmological role of cold dark matter. Hence, the framework connects scalar dynamics, effective dark-energy evolution, and the $H_0$ tension within a single setup.

We apply the Worldvolume Hybrid Monte Carlo (WV-HMC) method [arXiv:2012.08468] to the two-dimensional Hubbard model, which is known to suffer from a severe sign problem when the system is doped (away from half filling). We show that the method predicts physical observables with controlled statistical errors on an $8 \times 8$ lattice at temperature $T/t = 1/6.4 \approx 0.156$ and interaction strength $U/t = 8.0$ ($t$ is the hopping amplitude), for which the standard determinant quantum Monte Carlo fails.

The AMPS firewall argument relies on treating early radiation, late outgoing Hawking modes, and interior partner modes as approximately independent quantum subsystems. In diffeomorphism-invariant quantum gravity, however, gravitational dressing and asymptotic constraints obstruct such a tensor-product factorization of physical observables. In this essay, we sharpen this obstruction by formulating subsystem independence directly in operator-algebraic terms. Using modular theory, half-sided modular inclusions along null directions, and the sector-wise maximality of the dressed radiation algebra at future null infinity, we show that – within a fixed asymptotic charge sector – the algebra associated with the interior Hawking partner cannot form an independent commuting subalgebra, but must be contained as a (non-commuting) subalgebra of the radiation algebra itself. The subsystem-independence assumption underlying the AMPS paradox therefore fails, and the entanglement-monogamy step never becomes applicable. As a result, unitary black hole evaporation and semiclassical horizon smoothness are compatible in asymptotically flat quantum gravity, without invoking entanglement islands, replica wormholes, or modifications of semiclassical horizon physics.

We show that flying focus fields can be obtained from complex conformal transformation of plane waves, and that solutions of the massless wave equation in the so-obtained fields are, correspondingly, conformal transformations of the Volkov solutions. This leads to the result that photon emission amplitudes in a totally depleting flying focus beam may be computed directly from the corresponding plane wave amplitudes by taking a simple Gaussian average over certain momentum variables. In effect, this gives a way of introducing focussing effects into strong-field QED calculations `for free'. The extension of these results to scattering amplitudes including only partial depletion is discussed and some first results presented in the anti-self-dual limit.