Papers

We study admissible higher-spin algebras in four-dimensional Minkowski space, namely algebras that admit the tower of massless higher-spin fields as a representation. Under several simplifying assumptions, we show that these can be of two types, which we refer to as collinear and half-collinear. The chiral higher-spin algebra provides an example of the latter. For the collinear ansatz considered here, direct solution of the Jacobi identity yields two families of Lie algebras. We also find an associative collinear algebra, which is commutative unless internal degrees of freedom are added.

In this work we investigate how exotic spinorial topology modifies the propagation of fermionic modes in the Schwarzschild geometry. By incorporating a topological gradient, $\partial_\mu\varphi$, into the Dirac operator through a tetrad deformation, we show that the exotic spinorial sector naturally induces an effective geometric deformation of the Schwarzschild background. The central consequence of this construction is the emergence of a topological impedance surface at $\rtopo=1/q$, which suppresses the radial group velocity of the exotic spinorial modes, yielding a birefringent propagation pattern. Using a spinorial perturbation we discuss the greybody factor and the quasinormal response. The quasinormal spectrum shows the stability of the background metric and the absence of isospectrality for the superpartner potentials.

We prove, under some assumptions, the uniqueness of universal quantum dimension formulae. We first show that the quantum dimensions of classical algebras have a specific form that can be represented universally, in Vogel's sense, as the product/ratio of q-dimension factors with arguments $a\alpha+b\beta+c\gamma$ where $c=0, 1, 2$ and $a, b$ are integers. On this basis, we derive simple uniqueness criteria, according to which all known universal quantum dimensions are unique.

We report the first numerical examination of symmetric mass generation (SMG) for domain-wall fermions. Our simulation on a two-dimensional Euclidean lattice computes the path-integral of the Fidkowski-Kitaev Majorana chain with two boundaries, corresponding to the two (physical and mirror) walls. We demonstrate by evaluating the lattice Dirac operator eigenvalue spectrum that the local four-Fermi interaction selectively gaps the edge fermions on the mirror wall while leaving the physical wall intact. We further identify a characteristic signature of SMG in the path-integral: the gap of the Dirac operator opens along the imaginary axis of the complex spectrum, in contrast to the standard mass shift in the real direction. The conventional hybrid Monte Carlo algorithm remains practical with reweighting the complex phase of the Pfaffian, which is found to be remarkably small throughout the simulation. These results provide a practical nonperturbative framework for interaction-induced mirror-fermion decoupling of lattice domain-wall fermions.

We construct the Carrollian limit of the Cortés–Plyushchay wave equations for planar anyons, grading the spin-tower components by powers of $c$ and taking the limit at fixed rest energy. The result is a linear system describing Carrollian particles of any real spin — Carrollian anyons — and, at (half-)integer spin, Carrollian bosons, fermions and higher-spin fields. The system is a first-order square root of the standard Carroll wave equation $(\partial_t^2+E^2)\Phi=0$, whose spectrum consists of two flat branches at plus and minus the rest energy. Scaling the spin along with $c$, in the Carrollian analogue of the Jackiw–Nair limit, yields instead the exotic Carroll algebra, with a second central charge, non-commuting boosts, and observable coordinates spanning a noncommutative plane. We show how the Galilean and Carrollian theories branch from one common similarity transformation: the Galilean limit expels the negative-energy modes, whereas the Carroll limit retains both relativistic branches.

We study the topological structure of the quantum phase diagram of gapped systems by identifying the noncontractibility of loops, so-called $S^1$-families, within the gapped phase diagram in which many-body Hamiltonians can have nontrivial ground-state degeneracy. We manifest the role of symmetries in such $S^1$-family classifications by the exotic symmetry interplay: (i) nontrivial mixed anomalies, (ii) semi-direct product relation between the spontaneously broken and the unbroken symmetries, and (iii) symmetry with noninvertible operators. We find that such structures lead to the novel $S^1$-family classifications inaccessible by earlier classifications based on “independent” symmetries. Furthermore, we construct lattice realizations of these $S^1$-families and explicitly demonstrate their novel algebraic structures.

On a compact connected section ${\cal S}$ of a supersymmetric $M$-horizon the Killing-spinor bilinears give a pointwise identity relating the warp factor $\Delta$, the rotation one-form $h$ and the two spinor norms, with nothing assumed about the norm of the Killing spinor. We derive three consequences of that unreduced identity. First, a single-point rigidity theorem: if $\Delta$ and $h$ vanish at one point of the section, then the flux vanishes identically, ${\cal S}$ is Ricci-flat and the horizon is $\mathbb{R}^{1,1}\times{\cal S}$. A single point replaces the usual global spinorial hypothesis. Second, the ${\rm Spin}(7)$ decomposition of the flux fixes $h$ algebraically and exhibits the invariant flux content of the scalar square $\Delta=4\Phi^2$ known in an adapted gauge, $\Delta=\frac{1}{108}\|w_{\bf 7}\pm\sigma({\cal Y}_{\bf 7})\|^2$. Only the two ${\bf 7}$-summands $w_{\bf 7}$, ${\cal Y}_{\bf 7}$ reach the warp factor, and the square is degenerate rather than definite: it vanishes on the linear subspace $w_{\bf 7}=\mp\sigma({\cal Y}_{\bf 7})$ rather than at the origin, so positivity of $\Delta$ yields no case list. Third, the two combine into a pointwise budget: the single constant of supersymmetry is shared between the deviation from staticity and the ${\rm Spin}(7)$ mismatch of the flux, each bounded by that constant. The same identities characterise the constancy hypothesis, equivalent to $V=-fh$ for the bilinear one-form $V$, which fails on the static branch of known warped $AdS_2$ solutions; they fix a weighted integral of the warp factor; and they reduce the Komar angular momentum of the horizon to a positive bilinear integral. Two no-go statements, for hidden symmetries built from the Killing spinor and for a second isometry from its bilinears, are stated with their hypotheses.

We investigate the dynamical behavior and spread complexity of quantum states within the mass-deformed BMN matrix model equipped with an emergent $U(1)$ global charge at finite temperature $\beta^{-1}$ and chemical potential $\nu$. Focusing on the strong-coupling regime ($\mu \gg 1$), we model the dynamics via a charged Thermofield Double (cTFD) state and trace the evolution of spread complexity across three distinct thermodynamic regimes. In the low-temperature gapped phase ($\beta \mu \gg 1$), discrete mass-gap bound states dominate, trapping wavepacket dispersion and producing non-chaotic, oscillatory early-time growth. Conversely, in the high-temperature continuum phase ($\beta \mu \ll 1$), thermal excitations overwhelm the mass gap, driving a transition to a continuous advection field that exhibits maximal chaotic scrambling with a Krylov Lyapunov exponent $\lambda_K = \pi / \beta$ that saturates the universal bound. In the intermediate temperature regime ($\beta \mu \sim 1, \beta \nu \sim 1$), the interplay between mass-gap bound states and the continuous thermal background induces a sub-leading correction to the Lanczos coefficients $b_n \sim \frac{\pi}{\beta} n + \gamma \sqrt{n}$, governing a continuous sub-exponential crossover before full chaotic thermalization. Technical derivations regarding KMS boundary conditions, grand canonical spectral moments, residue analysis, and time-reversal symmetry breaking in Krylov space are detailed in four dedicated appendices.

We study a local constrained problem at matrix size $N=5$ in the Lorentzian IIB (IKKT) matrix model and numerically continue a one-dimensional physical modulus. For an exact fixed-$Q_\rho$ constrained solution family, the stationary identity implies constant classical action; the 23 accepted backgrounds realize this relation to the quoted precision. Across the sampled branch, the spectrum of the Lorentzian extent operator remains common to numerical precision while microscopic noncommutative invariants vary. We evaluate finite-dimensional one-loop fluctuations along this branch. At fixed bosonic background, the fermionic Grassmann integral is exact and gives $\operatorname{Pf}\mathcal M_F$; its magnitude is invariant under color-gauge and connected proper-Lorentz transformations and varies along the modulus. The complete boson–ghost–fermion quotient measure defines a Lorentz-representative-independent density one-form rather than a scalar potential. Thus quantum fluctuation data distinguish backgrounds unresolved by the coarse quadratic spectrum. We also apply a framed higher-$L$ SO(5) structural probe. At the reference background, the ordered $3+6$ spectral separation is larger at $L=2,3$ than at $L=1$, and larger still in the canonical large-$L$ limit. This is a frame-defined diagnostic, not an intrinsic observable or a higher-$N$ solution. The Pfaffian and higher-$L$ responses are closely correlated along the sampled branch, which we treat only as descriptive. These results suggest that microscopic noncommutative structure and quantum fluctuations may contain information relevant to dimensional dynamics, without establishing dimensional selection.

We introduce latent geometry in BFSS/BMN models. Before an emergent geometry evaporates at the geometric transition, large-$d$ Gaussianization encodes its information in the exceptional $N=2$ sector selected by the baby fuzzy sphere, a single active spin-$1/2$ Pauli block. Dimensional reduction, finite-$N$ Gaussianization and exact Molien–Weyl projection transport this encoding to mass-deformed BFSS$_2$. At $N=2$, the same stable BFSS$_2$ oscillator admits inequivalent unitary $\mathbf{H}^2_\theta=\mathbf{EAdS}^2_\theta$ and $\mathbf{dS}^2_\theta$ decodings, realizing spacetime transmutation and the emergence of Lorentzian time.

We study genuine multi-entropy in Abelian $U(1)_k$ Chern-Simons theory. For key-ring link states, where only the linking numbers between one distinguished component $K$ and the remaining $\mathtt{q}-1$ components are nonzero, we derive an exact closed-form expression for the $\mathtt{q}$-partite Rényi multi-entropy for general $\mathtt{q}$, level $k$, and Rényi index $n$. For $\mathtt{q}=4$, this shows that the genuine multi-entropy $\mathrm{GM}^{(4)}_n$ collapses exactly onto the tripartite information $I_{3,n}$ for all $n$, while for $\mathtt{q}=5$ it is likewise completely determined, for all $n$, by a linear combination of tripartite and bipartite Rényi multi-entropies. We then go beyond the key-ring class and study general four-component link states with arbitrary pairwise linking numbers. A numerical scan over Chern–Simons levels $2\leq k\leq24$ shows that the all-$n$ collapse found analytically for key-ring states does not survive for generic link states. Remarkably, the collapse remains exact at $n=2$ for every level examined. At $n=3$, violations occur, within the scanned range, only when $3\mid k$, with a further dependence on the $3$-adic valuation of $k$. At $n=4$ and $n=5$, violations occur for every level examined, with rates that vary strongly with $k$. These results show that the breakdown is not controlled simply by the zero-divisor structure of composite $\mathbb Z_k$, but instead exhibits a nontrivial joint dependence on the Rényi index and the arithmetic structure of the Chern–Simons level.

We study the holographic duality between free vector models and Higher-Spin Gravity in 4-dimensional de Sitter space. On both the bulk and boundary sides, we introduce new reality conditions, which allow us to include odd spins in the bulk, and to extend the duality from type-A to type-B (i.e. from boundary scalars to spinors). The new reality conditions are closely related to a higher-spin-symmetric Hilbert-space norm for the single-particle (super)multiplet in de Sitter space. We construct two alternative viewpoints on the type-A and type-B theories. In one view, the two co-exist in "parallel universes", specifically in even vs. odd antipodal identifications of de Sitter space. In the other view, type-A and type-B are Legendre-transformed descriptions of the same twistor-space theory in Euclidean AdS (this involves the observation that the higher-spin partition function is Legendre-dual to itself). In this way, higher-spin holography reconciles the two-boundary nature of de Sitter space with the one-boundary nature of Euclidean AdS. The supersymmetric theory that unifies type-A and type-B with bulk fermions fails to be consistent under the appropriate reality conditions.

In Einstein gravity, every null geodesic of a non-static Bianchi I spacetime satisfying the null energy condition is incomplete in at least one direction within the Bianchi I region. We prove a stronger directional rigidity theorem: a single null geodesic complete in both affine directions forces staticity if the null curvature is nonnegative along it and, at each time, in one transverse null direction. The spatial metric need not be diagonal, and the expansion rates may have either sign. The proof uses caustic-free null congruences whose conserved spatial covectors define fixed screen hyperplanes. The two curvature conditions admit averaged replacements along the geodesic and, when cosmic time is complete, along comoving worldlines. In a non-static metric, at most four oriented directions are optically saturated; every other complete null geodesic has strictly negative averaged null curvature. Periodic and finite-pulse examples attain this bound with NEC-violating sources and nonpositive total energy density. For finite pulses, we derive bounds on metric excursions from three directional curvature budgets at fixed cosmic duration, and on the mode mixing of a free, massless, minimally coupled test scalar field from the averaged null-energy deficit at fixed affine duration.

The potential of $E_{8(8)} \times \mathbb{R}^+$ exceptional field theory, suited for studying three-dimensional maximally supersymmetric compactifications of higher-dimensional supergravities, is derived in teleparallel formulation. This means that, starting from an ansatz of the most general combination of the quadratic scalar contractions of the intrinsic torsion, which is manifestly invariant under generalised diffeomorphisms, one selects the potential by imposing the invariance under infinitesimal rotation of the maximal compact subgroup of the duality group. The teleparallel formulation makes manifest at geometric level the preeminent role of the intrinsic torsion in studying compactifications of higher-dimensional supergravities, where the intrinsic torsion is identified with the embedding tensor of the resulting gauged supergravity.

Quantum optomechanics (QOM) explores the interaction between a quantum field, often confined in a cavity, and the quantum motion of mirrors, membranes or material media, usually assumed slow enough with negligible particle production, which is the central concern of dynamical Casimir effects, and a drive laser field for effective control. This rapidly developing field has a wide range of applications, from quantum sensing to the detection of gravitational waves. Because the opto-mechanical coupling is nonlinear, most theoretical investigations assume that the amplitude of mirror motion $x$ remains small. Recent years saw several papers treating $x^2, x^3$ orders in the mirror displacement. In our work we take a different route, deploying the functional perturbative method presented in [1] and enriched in [2], applicable for sufficiently weak opto-mechanical couplings. With this we can treat arbitrary displacement of the mirror, not just at a higher order in a power series expansion in $x$. We first derive the influence action of the quantum field and its non-Markovian noises back-reacting on the moving mirror with self-consistency. From it we derive a nonlinear Langevin equation driven by these back-action noises from the quantum field. We then show how results from our general modeling and treatment can be linked with the models and the Langevin equations presented in the literature, starting with the popular radiation pressure $Nx$ coupling, with $N$ the photon number, up to the recent $x^3$ order results. We hope this new approach and the results presented here can provide useful theoretical support for high precision QOM experimentation in the future.

Recent results in the study of gravitational scattering amplitudes indicate that some highly-symmetric relativistic systems may exactly conserve a version of the Laplace-Runge-Lenz (LRL) vector in two-body bound states. We make a systematic study, in the context of a generic EFT of long-range interactions due to the exchange of massless mediator particles of spins 0, $\frac{1}{2}$, 1, $\frac{3}{2}$, 2, of the conditions for the conservation of a hidden LRL vector; both classically (no orbital precession) and quantum-mechanically (hydrogen-like degeneracy of bound states). The calculations require several new technical developments including the extension of relativistic post-Minkowskian potential matching to quantum corrections and the incorporation of long-range forces due to the exchange of pairs of massless fermions. We find that while classically the absence of precession is a generic property of a large class of models, including Kaluza-Klein theories, with vector and scalar exchanges, maintaining the degeneracy quantum-mechanically requires a surprising cancellation between gravitons and 6 Majorana gravitinos, hinting at a special role for $\mathcal{N}=6$ supergravity.

This article presents a systematic study of the critical cohomology of $\QM^{\xi}(\bbP^1, X)$, the moduli space of based quasimaps from $\bbP^1$ to a Nakajima quiver variety $X$. We develop two derived equivalent presentations of this moduli space as a global critical locus. Accordingly, we obtain two equivalent explicit realizations of the canonical DT sheaf of the moduli space. Using each critical presentation, we describe canonical actions of shifted Yangians and quantized Coulomb branches on the quasimap critical cohomologies. We produce, by geometric means, a canonical morphism from an appropriate Hall algebra to the Coulomb branch, and show that the two actions we describe are compatible via this morphism under an additional hypothesis. We conjecture the compatibility holds generally, and reduce the claim to a sheaf-theoretic statement that may be approached via Joyce conjecture.

The modular Hamiltonian plays an important role in quantum information theory, quantum field theory, and the AdS/CFT correspondence. In this paper, we study a specific dynamical setup: starting from the tensor product of the reduced density matrices of a reference state, we evolve this product state under the modular flow generated by the reference state itself. We then investigate the resulting change in the entanglement entropy of a given region, which we call the modular entanglement shift (MES). Unlike evolution under a fixed quantum channel, this modular evolution obeys no general principle requiring the MES to have a definite sign. For a bipartition into subsystems A and B, we establish an exact entropy balance: the sum of the MESs for A and B equals the mutual information generated along the orbit. Consequently, their sum is nonnegative, even though either individual shift may be negative. For two disjoint intervals in the vacuum of a two-dimensional conformal field theory, however, we prove that a global conformal involution exchanging the intervals forces the two MESs to be equal. It follows that each MES is nonnegative along the modular flow. We establish this result both using a conformally transported regulator and intrinsically in terms of Araki relative entropy. Finally, we identify the modular-flow orbit with a Connes cocycle orbit and discuss possible applications to the AdS/CFT correspondence.

When irreducible representations occur with multiplicity, a family symmetry fixes the representation content of a Yukawa sector but need not fix its embedding in the space of generation tensors. We study the spectral consequences of this additional embedding data for complex-symmetric three-family tensors with the $S_3$ assignment $V=\mathbf{1}\oplus\mathbf{2}$. Since $\operatorname{Sym}^2V=2\,\mathbf{1}\oplus2\,\mathbf{2}$, three-dimensional invariant Yukawa subspaces of type $\mathbf{1}\oplus\mathbf{2}$ form a continuous $\mathbb{CP}^1\times\mathbb{CP}^1$ family, denoted $\mathcal L_{t,\kappa}$ on a finite affine chart. On the $\kappa=0$ branch, we solve the inverse singular-value problem and obtain necessary and sufficient conditions for any prescribed ordered positive mass spectrum. A fixed singlet embedding imposes a finite hierarchy bound, whereas varying the embedding accommodates every positive three-family spectrum. For general embeddings, $\mathcal L_{t,\kappa}$ contains a nonzero rank-one matrix if and only if $2t\kappa^2=1$; equivalently, these are precisely the finite-chart embeddings for which $\sigma_3/\sigma_2$ is unbounded. In a conventional complex-symmetric $S_3$ three-Higgs sector, the same condition becomes $y_2y_5^2=\sqrt{2}\,y_1y_3^2$, so order-one Yukawa coupling ratios can support arbitrarily large mass hierarchies. We then apply the result to a recent Clifford-algebraic construction and show that its family-resolved Yukawa tensors span $\mathcal L_{2,0}$, whose singular values obey $m_1+m_2\leq m_3\leq m_1+3m_2$. This excludes the observed charged-lepton hierarchy for arbitrary complex vacuum alignment within the existing Higgs directions. The resulting obstruction is therefore tied to the fixed multiplicity embedding rather than to the $S_3$ representation content alone.

Models where an axion-like inflaton is coupled to a $U(1)$ gauge field are theoretically well motivated and can display a rich phenomenology. The regime in which the quanta of the gauge field strongly backreact on the rolling inflaton has been studied for well more than a decade, and yet we cannot say that it is fully understood. In this paper we present an analytical study of the onset of the strong backreaction regime. Our formalism relies on a Laplace transform to convert a complicated integro-differential equation into the search of the poles of an analytic function. We confirm the existence, previously observed using a completely different formalism, of a stable region of strong backreaction. Our work provides, for the first time, analytical formulae that allow to study the evolution of the system as it transitions from the weak to the strong backreaction regime.

We study the one-loop renormalization group flow of the translation-invariant noncommutative pseudoscalar Yukawa theory on four-dimensional Euclidean Moyal space. The two inequivalent orderings of the Moyal-star Yukawa vertex give rise to two independent couplings $g_{1}$ and $g_{2}$, whose beta functions form a coupled nonlinear system; every one-loop divergence is absorbed by a counterterm already present in the action, establishing one-loop renormalizability of the theory. We solve the one-loop system analytically: it decouples in the variables $u=g_{1}^{2}+g_{2}^{2}$ and $v=g_{1}^{2}-g_{2}^{2}$, the quartic coupling is obtained by a Riccati reduction on the symmetric surface $g_{1}=g_{2}$, and the generic asymmetric flow is reduced to a single quadrature by the exact invariant $\mathcal{I}=(g_{1}g_{2})^{3}/(g_{1}^{2}-g_{2}^{2})^{4}$. Two dynamical consequences follow. The ratio $r=v/u$ has a UV-attractive symmetric surface $r=0$ and IR-attractive asymmetric directions $r=\pm1$, so that the flow restores the symmetry between the two Moyal orderings towards the ultraviolet and amplifies any initial ordering asymmetry towards the infrared, as a fractional power of the logarithm. In consequence the Yukawa-induced coefficient of the non-planar $1/(\theta^{2}p^{2})$ structure is dynamically suppressed towards $p\rightarrow 0$; the singularity itself is not removed, and remains the task of the IR-improving term. We also solve the dimensionful sector ($M^{2}$, $m$, $a^{2}$ and $b$) in closed form on the symmetric critical trajectory, and compare throughout with the commutative theory.

The flat DHS connection $\mathcal J_{\mathrm{DHS}}$ constructed in arXiv:2602.01461 is smooth on the configuration space of $n$ points on a fixed compact Riemann surface $\Sigma$ of arbitrary genus $h$, takes values in an infinite-dimensional Lie algebra $\hat{\mathfrak t}_{h,n}$ and is invariant under the modular group $\mathrm{Sp}(2h,\mathbb Z)$. This paper is the first in a series for a program whose goal is to extend the connection $\mathcal J_{\mathrm{DHS}}$ to a global flat connection on the Teichmüller space $\mathcal T_{h,n}$ valued in the Lie algebra of derivations of $\hat{\mathfrak t}_{h,n}$. Upon the choice of local coordinates adapted to the map $\mathcal T_{h,n}\to \mathcal T_h$, such a connection splits into three pieces: $\mathcal J_{\mathrm{DHS}}$, a piece $\mathcal L$ corresponding to holomorphic directions of $\mathcal T_h$ and a third piece corresponding to anti-holomorphic directions in $\mathcal T_h$. In this paper, we isolate the system of equations satisfied by $\mathcal L$ and obtain its solution locally and explicitly. The construction of a global extension of $\mathcal J_{\mathrm{DHS}}$ to $\mathcal T_{h,n}$ and the extension of the meromorphic connection of arXiv:1112.0864 to $\mathcal T_{h,n}$, are relegated to future publications in this series.

We point out that a non-invertible selection rule can control the flavor violation inherent in lepton portal dark matter, a weakly interacting massive particle candidate that can evade severe constraints from direct detection experiments. We show that ordinary invertible symmetries cannot suppress flavor-violating portal couplings while accommodating the large mixing angles in the PMNS matrix. We then present a simple construction based on the $\mathbb{Z}_2$ gauging of a $\mathbb{Z}_5$ symmetry, which realizes one-flavor dominance of the portal couplings consistently with the PMNS mixing matrix. We also discuss possible flavor leakage in a type-I seesaw completion and study experimental probes of the model through lepton observables, especially lepton flavor non-universality in $Z$ boson decays.

The Schrodinger equation in one spatial dimension admits a small set of exactly solvable potentials that serve as natural proving grounds for any new eigenvalue solver. We formulate Physics-Informed Neural Networks (PINNs) and Physics-Informed Quantum Neural Networks (PIQNNs) for the time-independent Schrodinger equation and apply them to three of these benchmarks: the harmonic oscillator, the infinite square well, and the finite square well. In each case a composite loss encodes the differential-equation residual, the normalization condition, the boundary behavior, and the orthogonality between eigenstates, so that the trial wave function is driven toward a genuine eigenfunction without supervised data. The eigenvalues and wave functions returned by both methods are compared against the exact spectra and against three classical references: the matrix Numerov method, the finite difference method, and the shooting method. For the smooth oscillator the two neural solvers reproduce the lowest four eigenvalues to parts per million, while for the square wells they recover the analytic levels with comparable fidelity even where the potential is discontinuous. The quantum circuit, built as a layered angle-embedding ansatz with strongly entangling blocks, converges more reliably than its classical counterpart on the higher excited states, where the loss landscape of the classical network becomes harder to navigate.

We study slowly rotating Bose–Einstein condensate (BEC) dark stars by solving the Tolman–Oppenheimer–Volkoff, Hartle dipole, and Postnikov–Hinderer equations together for a polytropic equation of state with a Lee–Huang–Yang correction of strength $\zeta$~\citep{Panotopoulos2026}. A continuous scan of $\zeta$ from 0 to 1.5 shows the mean-field-to-corrected transition is smooth, with no hidden structure at intermediate values. Scanning the underlying boson parameters $(m,a_s)$ more broadly, we find that a $2\,M_\odot$ maximum-mass bound and a GW170817-like tidal bound $\Lambda_{1.4}\lesssim800$ cannot be satisfied simultaneously anywhere in this equation-of-state class. The $I$-Love universal relation holds to $0.13\%$ across twelve $(m,a_s,\zeta)$ models, and the $\zeta=0$ and $\zeta=1$ sequences sit on opposite sides of the master curve by a consistent, non-random offset. Applied without modification to realistic nuclear matter (SLy, APR4), the same solver reproduces published maximum masses to within $1\%$; applied to self-bound MIT-bag quark matter it gives the expected mass–radius shape; and once extended to a two-fluid baryon-plus-dark-matter formalism, it shows that the maximum mass of a hybrid star is not a monotonic function of the central dark-matter fraction. Pooling $I$-Love sequences across nuclear, hybrid, and BEC dark-star models, we find they collapse onto a single curve to within about $5\%$, while self-bound quark stars sit far off it, departing by up to $90\%$.

This paper introduces formalism, based on worldline effective field theory, which allows one to systematically calculate the gravitational self-force on a compact object immersed in an environment with non-vanishing stress energy. Using the closed time path integral we present a universal effective action that can be used to calculate the equations of motion of a compact object due to its interaction with the environment to any order in the relevant expansion parameters, the relative importance of which depends upon the choice of environment. We show that the leading order equations of motion can be universally written in terms of the retarded two-point function of the stress-energy tensor for the environment. The resulting action can be used to calculate both dissipative (dynamical friction) and conservative forces in a completely relativistic fashion. We demonstrate the utility of the result by calculating the dissipative force due to dust, an inviscid fluid, and a coherent field. Our results agree with those previously derived in the literature. We furthermore show that the famous “Coulomb Log" found by Chandrasekhar should be interpreted as a renormalization group log due to a UV divergence that renormalizes the dissipative part of the in-in action. We then prove that this log is universal in the Newtonian limit in that its value is universal, for a generic class of environments and trajectories. This log is the leading log in an RG flow in the dissipative action that has yet to be explored.

We develop a phase space description of large $N$ Hermitian one matrix models directly from the recursions satisfied by the orthogonal polynomials. In the one-cut phase, the recursion lattice naturally gives rise to a semiclassical action-angle pair, which can be mapped canonically to eigenvalue and momentum variables. We show that the resulting momentum profile is determined by the density of zeros of the orthogonal polynomials, and that the same phase space structure is reproduced from the Wigner transform of the Christoffel-Darboux projector and from the planar spectral curve. The Gaussian model provides a simple consistency check of the proposal. We then extend the construction to the symmetric quartic two-cut phase, where a period-two Jacobi recursion produces two Bloch bands and two disconnected phase space components with actions given by the partial 't Hooft couplings. Finally, we outline the finite-gap generalization appropriate to multicut phases.

It is natural to expect that the electromagnetic spin-spin interaction has roots in a more fundamental theory: quantum electrodynamics in this case. To show this, we take the non-relativistic limit of the Dirac-Maxwell Lagrangian, using the Foldy-Wouthuysen transformation and derive the Breit interaction by an alternative approach. By adding the Pauli term (i.e., a higher-order interaction between spin and the electromagnetic field), we calculate the correction terms to electromagnetic spin-spin interactions in the non-relativistic limit. Finally, we study some of the physical effects of these terms regarding spin-spin interactions and spin-spin entanglements. Accordingly, we provide theoretical estimates that are not yet accessible with current experiments.

The existence of quantum gravity is the most important question in theoretical physics. Besides the theoretical development in this direction, looking for its low-energy consequences can provide clues. However, besides availability, it is crucial to ensure that what is observed uniquely comes from quantum gravity and not from other forces in the environment. What is the unique feature of gravity? The spin-$2$ nature of its propagator. In this Letter, we calculate what the unique feature of the spin-$2$ graviton is in the interaction of two spin-$\frac{1}{2}$ particles. This unique feature shows itself in intertwining the spin and momentum of two particles simultaneously as a dipole-dipole interaction. This cannot happen for any spin-$0$ or spin-$1$ propagator, at least at leading order, which scales as $\frac{1}{r^3}$ in real space. We re-calculate the results using an independent approach, i.e., the Foldy-Wouthuysen transformation, and reach the same results. Due to simultaneous coupling of both particles' spins and momenta, a four-partite entanglement framework is suggested to observe this effect.

Since the first exact solutions of General Relativity (GR) were obtained, it became clear that the theory predicts a new class of compact objects: black holes. The Hawking–Penrose singularity theorems show that, under appropriate assumptions, gravitational collapse in GR leads to singular behavior. Motivated by the expectation that such regimes require physics beyond classical GR, effective approaches inspired by Loop Quantum Cosmology (LQC) and braneworld scenarios introduce high-density corrections. In this work we consider the static exterior geometry introduced by Gao, Lu, Shen, and Faraoni, associated with a comoving interior model in which the singularity is avoided through a sequence of collapse and bounce phases. Using the Newman–Janis algorithm in the Azreg-Aïnou formulation, we construct a stationary rotating exterior extension of this geometry. The resulting line element describes a stationary axisymmetric rotating spacetime whose horizon geometry, angular velocity, surface gravity, and Hawking temperature recover the Kerr and Schwarzschild limits when the quantum/braneworld correction becomes negligible ($l\to 0$). We further analyze the thermal response at fixed rotational state-space parameter, identify Davies-type singular points, and formulate an extended thermodynamic state-space relation.