Papers

An effective field theory (EFT) of gravity with a cubic Riemann invariant coupled to an axion-like field is investigated and shown to propagate no additional independent low-energy degrees of freedom. This interaction generates a curvature-induced scalar profile around black holes, characterised by a secondary axion charge fixed by regularity of the axion field at the horizon, while the requirement of a regular event horizon constrains the asymptotic axion background. We construct the corresponding black hole solutions and show that the backreaction of the axion field could affect the metric only at subleading order in the EFT expansion. The modified geometry impacts black hole thermodynamics and Hawking evaporation, thus providing a controlled realisation of black holes with higher-curvature contributions and secondary axion hair motivated by ultraviolet physics. The modified Hawking temperature allows for the existence of black hole remnants at the end of the evaporation within the regime of validity of the EFT.

We investigate dynamical dark energy emerging from quantum gravity within the framework of group field theory (GFT) condensate cosmology. We generalise previous models of quantum gravity induced cosmic acceleration by considering a broader parameter space, including an additional scalar matter field besides the relational clock, and accounting simultaneously for the phase dynamics and the contribution of multiple condensate modes. Working in a mean-field approximation with coherent peaked states and restricting to Hermitian GFT interactions, we derive the corresponding effective cosmological dynamics and analyse its late-time behaviour. We show that the system approaches an asymptotic de Sitter regime, dynamically dominated by a single condensate mode, while the approach to this regime can exhibit a non-trivial dynamical dark-energy evolution. In particular, both the condensate phase and subdominant modes can generate deviations from the asymptotic equation of state $w=-1$, including phantom behaviour and, under suitable conditions, a crossing of the phantom divide. The additional scalar matter field enters directly into these conditions, providing a link between the matter content and the quantum gravity induced dark-energy dynamics. These results extend the robustness and generality of the GFT mechanism for dynamical dark energy and provide a basis for confronting the underlying quantum gravity dynamics with cosmological observations.

We develop a holographic dual to the integrable field theories built from $4d$ Chern-Simons theory. The dual theory is a topological string on a generalized Calabi-Yau manifold, which is entirely encoded in a geometric object we call a planar spectral curve. We describe the RG flow for a planar integrable field theory as a geometric flow on the moduli of planar spectral curves. This description is valid at all orders in the 't Hooft coupling. We compute this flow explicitly up to two loops in many examples, and find an exact match with known field theory results. At one loop this includes a wide class of models. At two loops we reproduce the RG flow for the principal chiral model with WZ term, and for a class of integrable $\sigma$-models with target $U(N) \times U(N)$.

In the present study, we investigate the phase diagram of strongly-interacting fermions under imaginary rotation. We employ the linear sigma model coupled to quarks in the mean field approximation. The fermion expectation values are computed in the local density approximation (LDA), using the well-known expressions derived using cylindrical modes for states under rigid rotation, at finite temperature $T$ and chemical potential $\mu$. We study the impact of the fractalization of thermodynamics on the phase diagram in the far-field limit (far from the rotation axis). We also reveal non-trivial features such as a complete inhibition of the chiral symmetry restoration on the rotation axis above a critical imaginary angular velocity. We demonstrate explicitly how the transition line interpolates between its shape on the rotation axis and in the far-field limit by studying the chiral phase transition at finite distances from the rotation axis. We also address the moment of inertia of the system and discuss differences and similarities to lattice studies of QCD matter under imaginary rotation.

The exact one-point function of Liouville theory on the real projective plane was derived long ago from the bootstrap, yet it has never been verified against a semiclassical path-integral computation. The check is less straightforward than one might expect. On the real projective plane every constant-curvature metric is positively curved, whereas classical Liouville theory produces metrics of constant negative curvature, so no real classical solution exists. Instead, as we show, the semiclassical path integral receives contributions from infinitely many complex saddles with a negative-definite metric. Once the integration contour is chosen so that the path integral converges, these saddles reproduce the exact one-point function. Complex saddles arise in the same way in timelike Liouville theory and in two-dimensional de~Sitter gravity, and the example treated here offers a rare opportunity to test their use against a known exact answer.

In this paper we extend a study of the validity conditions of the separate universe approach of cosmological perturbations to models of inflation with multiple fields that are non minimally coupled to gravity. The separate universe approach effectively describes the universe as a collection of homogeneous and isotropic patches, leading to an effective description of cosmological perturbations at large scales. This approximation is a necessary step in stochastic inflation and in the $\delta \N$ formalism. We study and compare the dynamics of cosmological perturbation theory at large scales to the dynamics derived in the separate universe picture for non linear sigma models where we have allowed a non minimal coupling between the fields and gravity. We found that the separate universe approach adequately reproduces the dynamics of the large scale perturbations, provided the wavelength of the modes considered is greater than a list of lower bounds derived from the background evolution of the model we consider. These lower bounds are then compared to those derived in the classically equivalent Einstein frame description of the Jordan frame model at hand. In particular these conditions are derived and compared for a Higgs-like toy model of inflation in the large field limit.

As was shown in arXiv:2609.14497, the 2-loop $ {\rm T}^{-1}_2$ correction to the partition function of M2 brane wrapping $\mathrm{AdS}_2\times S^1$ inside $\mathrm{AdS}_4\times S^7/\mathbb{Z}_k$ vanishes. This is in agreement with the localization prediction for $\frac{1}{2}$-BPS circular Wilson loop in ABJM theory interpreted in the grand-canonical ensemble according to the conjecture of arXiv:2505.21633. Here we study the ${\rm T}^{-1}_2$ correction for the M2 brane instanton wrapping $S^3/\mathbb Z_k\subset S^7/\mathbb Z_k$ dual to the leading non-perturbative large $N$ contribution to the ABJM free energy on 3-sphere. The 1-loop instanton M2 brane partition function was shown in arXiv:2307.14112 to match the localization prediction. The 2-loop computation is complicated by the presence of bosonic and fermionic zero modes, which requires to integrate over the collective coordinates. The collective-coordinate Jacobian provides a non-trivial ${\rm T}^{-1}_2$ contribution in addition to the one of the quartic interaction vertex in the M2 brane action. We find that for $k>2$ the the quartic vertex contribution is cancelled by the Jacobian contribution for the choice of the separation of the fermionic zero modes from the quantum fields under which these form separate supermultiplets. Assuming the supersymmetric prescription for the paired zero modes we show that the cancellation persists after integration over the collective coordinates. Thus the ${\rm T}^{-1}_2$ correction vanishes, in agreement with the grand-canonical ensemble prediction. For $k=1$ the quartic vertex contribution reduces to equation-of-motion terms as in the case of ${\rm AdS}_3 \subset { \rm AdS}_7 \times S^4$ in arXiv:2511.22306 which is related to $S^3 \subset {\rm AdS}_4 \times S^7$ case by a formal analytic continuation.

We define the classical BV pushforward and establish its two main properties. First, we prove that it maps solutions of the classical master equation (CME) on the total space to solutions of the CME on the smaller space. Second, we prove that, for isolated critical points, it maps BV canonically equivalent solutions to BV canonically equivalent solutions. We illustrate the construction with examples and discuss its applications.

We distinguish two Casimir observables associated with a conformal surface defect. A circular cylinder embedded in flat space has a logarithmic contribution to its Casimir energy, $-d_1\log(R/\epsilon)/(24R)$, fixed by the displacement anomaly. A great cylinder obtained by radial quantization of the ambient theory instead has Casimir energy $-b/(12R)$ in the conformal defect vacuum with a fixed local anomaly convention. Free-field and holographic calculations provide checks of the proposed relations in both embeddings.

In this article, we examine particle dynamics and Quasi-periodic oscillations within a charged Simpson-Visser-Anti-de Sitter (AdS) spacetime. We first analyze the behavior of the metric and black hole horizons under the competing impact of electric charge $Q$, regularization parameter $b$, and AdS radius $l$. The roots of the metric function reveal transitions between three distinct topological classes: non-extremal configurations featuring distinct inner and outer horizons, extremal limits with a single degenerate horizon, and strictly positive, horizonless wormhole geometries. By evaluating the effective potential, we determine how this modified geometry shifts the Innermost Stable Circular Orbit (ISCO) and alters the angular momentum and energy of test particles. Moreover, we derive the Keplerian, radial, and vertical frequencies to model quasi-periodic oscillations (QPOs). We show that the interplay between the regularization parameter $b$ and the AdS radius $l$ significantly modifies twin-peak QPOs. In particular, $b$ drives fundamental QPO frequencies higher than those predicted by standard general relativistic backgrounds. Twin-peak high-frequency QPO data from two black-hole binaries disfavor the Schwarzschild limit at $\sim\!4\sigma$, but constrain only a degenerate combination of charge and AdS curvature, leaving the regularization parameter entirely unconstrained by the data.

Relic neutrinos retain a record of electromagnetic entropy production after neutrino decoupling, probing primordial modes erased from the primary CMB. We derive the cubic photon number source from acoustic damping and its leading folded sensitive bispectrum window, with neutrino decoupling, thermalization, and acoustic coherence combined in a single response kernel. For excited initial states, this kernel filters the physical folded profile and yields a sharpness dependent transmission condition, directly connecting small scale primordial non-Gaussianity to relic neutrino capture rates.

We compute the anomalous dimensions of the leading-twist operators at three-loop level in the $\overline{\text{MS}}$ scheme in the Gross-Neveu-Yukawa model. Calculations are done for a number of low-spin operators using computer algebra systems, and the analytical form is reconstructed by solving a set of Diophantine equations. Calculations are optimized using the emergent supersymmetry of the corresponding generalized theory. For the obtained results, we perform a comprehensive analysis at the critical point, including a comparison with the $1/N$ expansion, a check of the generalized Gribov-Lipatov reciprocity, and an analysis of the behavior next to the rightmost singularity. The latter allows us to extract the values of Regge intercepts for all the leading-twist trajectories in the form of an $\epsilon$ expansion.

We establish an exact correspondence between renormalization-group (RG) evolution and real-time quantum dynamics in the anisotropic current-current perturbed $SU(2)_1$ Wess-Zumino-Witten (WZW) model. Using its integrable fermionic representation, we construct the exact time-dependent many-body wavefunction by means of the generalized Bethe ansatz and show that periodic boundary conditions lead to quantum Knizhnik-Zamolodchikov equations associated with the XXZ trigonometric $R$-matrix, which corresponds to the quantum affine algebra $\mathcal{U}_q(\widehat{\mathfrak{sl}_2})$ evaluated in its spin-$1/2$ evaluation representation. Consistency of these equations constrains the temporal evolution of the longitudinal and transverse interaction strengths. In the universal regime, these integrability conditions are exactly equivalent to the Berezinskii-Kosterlitz-Thouless RG flow equations upon identifying physical time with the logarithmic RG scale. Consequently, the RG limit cycles of the anisotropic current-current perturbed $SU(2)_1$ WZW model are realized as periodic real-time evolution of its interaction strengths. Our results provide an exact dynamical realization of RG limit cycles and establish a direct connection between cyclic RG flows, quantum integrability, and periodically driven interacting quantum field theories.

We investigate some aspects of holography in de Sitter space, pertaining to the proposal for the dual theory residing on the late-time boundary [arXiv:astro-ph/0210603v5], including a Fermionic field that satisfies the Dirac equation. The modes of the solutions near the boundary are found to possess equal and oscillatory fall-off, similar to the scalar field belonging to the principal series representation of the isometry group of de Sitter space. We evaluate, by suitably adding a boundary term to the Dirac action, the wavefunctional of the Bunch Davies vacuum in path integral formalism in terms of the projections of the field on the eigenspaces of the time-like ${\gamma}$-matrix. We validate our path-integral construction of the wavefunctional by reproducing the two-point function between the field operators in the vacuum state as computed in the canonical formalism. By appropriately identifying the boundary sources in terms of the projected components of the bulk field, we find that a single Dirac field in the bulk corresponds to a pair of primary spinor fields in the boundary theory and show that the resulting wavefunction coefficients satisfy the conformal Ward identities. We check the robustness of our holographic map under the addition of a Yukawa interaction considering the two cases where the scalar field in the interaction term belongs to the complementary series and the principal series representations of the isometry group of de Sitter space respectively.

We investigate $\mathbb{Z}_2$ symmetry restoration in a real $\lambda\phi^4$ theory confined to a finite cylindrical region undergoing rigid rotation. The finite transverse extent is imposed through Dirichlet boundary conditions, resulting in a discrete Fourier-Bessel spectrum and an explicit radial dependence of the fluctuation propagator. Using the background-field method, we derive the one-loop effective potential while retaining the spatial structure induced by the finite geometry. At finite temperature, rotation modifies the thermal mode energies through angular-momentum-dependent shifts, and the coincident-point propagator generates a position-dependent thermal self-energy that is incorporated through ring resummation. We use the resulting spatially resolved effective potential to determine the symmetry-restoration temperature $T_c(\Omega,R)$ and examine its dependence on the angular velocity and transverse size. The results show that the finite transverse size of the system modifies the symmetry-restoration temperature, leading to a nontrivial dependence of $T_c(\Omega,R)$ on $R$. An additional scaling behavior emerges when the normalized critical temperature is expressed in terms of the boundary velocity $\Omega R$: systems with different transverse sizes exhibit the same relative modification of $T_c$ when their boundary velocities are equal. This scaling persists after the inclusion of the position-dependent thermal self-energy through ring resummation, indicating that the $\Omega R$ dependence of the rotational response is maintained in the interacting finite system.

The geometric shadow of a black hole cannot observationally distinguish horizonless exotic compact objects. We break this degeneracy by mapping the fundamental quantum decoherence of the horizon (the Danielson-Satishchandran-Wald mechanism) into a macroscopic effective reflectivity $\mathcal{R}$. Utilizing Kerr ray tracing, we show that a partially reflective boundary ($\mathcal{R}>0$) generates delayed electromagnetic echoes under both specular and diffuse (Lambertian) conditions. In the spatial domain, these echoes illuminate the inner shadow and alter low-frequency visibilities, while leaving metric-governed photon subrings unchanged. The signal strength scales with the membrane compactness $\epsilon$ as $\epsilon^{\Gamma}$, where $\Gamma=0$ for specular reflection and $\Gamma\to1$ for diffuse re-emission due to escape-cone collapse. This brings specular reflectivities down to $\mathcal{R}\simeq0.12$ (ngEHT) and $0.04$ (BHEX) within reach of static imaging. For Sagittarius A$^\ast$, we translate these echoes into a robust time-domain signature. Using an Autocorrelation Function (ACF) pipeline, we demonstrate that single-flare echoes can be cleanly extracted from severe accretion red noise, achieving a $3\sigma$ detection for amplitudes $\mathcal{A}\gtrsim0.3$ within 15 to 33 hours of continuous monitoring. This framework provides a directly deployable pathway to test black hole unitarity.

In this paper we revisited the analyse the vacuum polarizations effect associated wit charged matter fields in a higher-dimensional anti de-Sitter (AdS) spacetime in the presence of an idealized cosmic string carrying magnetic flux running along its core. Specifically we will consider, separately, charged bosonic and fermionic fields propagating in this manifold. Our main objective is to calculate the vacuum expectation values (VEV) of the energy-momentum tensor, $\langle T^\mu_\nu\rangle$, associated with both matters fields. As will see, these VEVs are even function of the magnetic flux running along the string's core, with period equal to the quantum flux $\Phi_0=\frac{2\pi}{e}$. Because the results obtained are expressed in terms of special functions, and a clear behavior for them are not very enlightening, we provide some graphs exhibiting their behavior as function of the distance to the string considering different values for the parameters presented in the model considered.

Within the Hatta-Yang holographic graviton-dilaton amplitude for near-threshold $J/\psi$ photoproduction, we identify exact dilaton-null spin-projection channels in the Gottfried–Jackson basis. The $m=0$ and $m=-\lambda_\gamma$ amplitudes receive no dilaton contribution; for photon polarization normal to the reaction plane the $m=0$ channel further isolates $A_g(t)+B_g(t)$ and requires nucleon spin transfer. Standard beam-polarization spin-density-matrix elements then furnish a TT-sensitive combination and a second bilinear containing linear dilaton-TT interference. Comparison with modern GlueX and CLAS12 cross sections shows substantial sensitivity to the shape of the original holographic parameterization. The polarization observables therefore provide direct probes of the tensor structure of the production amplitude.

We present an extension of the Standard Model based upon the gauged $U(1)_{L_\mu - L_\tau}$ symmetry, featuring an ultra-light vector boson that couples to the difference of muon and tau lepton numbers. This anomaly-free construction, historically motivated by the muon's anomalous magnetic moment, is employed here as an independent phenomenological framework for solar neutrino physics. Through kinetic mixing with the photon, the $Z^\prime$ boson generates an effective matter potential within the solar interior, thereby modifying neutrino flavour oscillations via the Mikheyev–Smirnov–Wolfenstein mechanism. Utilising recent solar neutrino measurements from Borexino, SNO, and Super-Kamiokande, together with an up-to-date standard solar model, we constrain the boson mass to be below $5.7\times 10^{-17}\,{\rm eV}$, a potential ultra-light dark matter candidate. The optimal model, with coupling parameter $\eta_o \approx -2$, yields $\chi_\nu^2 = 2.7$, compared with $\chi_\nu^2 = 3.1$ for the standard three-flavour scenario. This best fit corresponds to an effective four-fermion coupling $g_{Z^\prime}^2 \varepsilon / m_{Z^\prime}^2 \approx 6.6 \times 10^{-23}\,{\rm eV}^{-2}$, approximately $5.7$ times the Fermi constant, equivalent for $\varepsilon \approx 1$ and a reference mediator mass of $1\,{\rm eV}$ to a gauge coupling $g_{Z^\prime} \approx 8\times 10^{-12}$. We also present projections for forthcoming experiments: the Jiangmen Underground Neutrino Observatory (JUNO), operating since August 2025 with world-leading precision on oscillation parameters, together with the XLZD consortium, should substantially refine these constraints. Such ultra-light particles may address long-standing discrepancies in galaxy simulations within the cold dark matter paradigm, whilst terrestrial long-baseline neutrino experiments provide complementary probes of this parameter space.

We show that a heavy higgsino $\tilde h$ with mass $m_{\tilde h}\sim0.1~{\rm PeV}$, which can be made consistent with the recent LUX-ZEPLIN event avoiding constraints from direct and indirect detection, can account for the present cold dark matter abundance of the universe, if the reheating temperature is bounded as $T_{\rm rh}\lesssim 595~{\rm GeV}$. These values can be achieved by a possible out-of-equilibrium decay of a modulus $\phi$ with mass $m_{\phi}\gg m_{\tilde h}$ and a non-vanishing branching ratio into $\tilde h$'s which plays a decisive role in reducing $T_{\rm rh}$ below its upper limit via the non-thermal $\tilde h$ production. The modulus $\phi$ can be identified with the scalar component of the goldstino superfield which is involved in the generation of the $\mu$ parameter of MSSM (with $\mu\simeq m_{\tilde h}$) via the Giudice-Masiero mechanism.

We quantize the charged sector of the electroweak theory in an external electromagnetic plane-wave background after spontaneous symmetry breaking, which we refer to as the electroweak Volkov-Proca theory, and analyze its global $U(1)$ symmetry and continuous residual translation subgroup together with the associated conserved charges and momentum components that label the states. We further derive the completeness and orthonormality relations for the Volkov-Proca states in Ritus form, and construct the off-shell and on-shell propagators, including their representation in terms of the scalar Volkov propagator. Finally, we derive the Källén-Lehmann spectral representation and the LSZ reduction formula for the Volkov-Proca states.

The renormalization of asymptotically AdS spacetimes in New Massive Gravity is studied using boundary terms constructed with the extrinsic curvature. For generic values of the theory couplings, a single extrinsic boundary term produces a consistent holographic description, as the variation of the total action is finite and expressible in terms of the holographic source. This prescription applies to constant-curvature geometries and non-Einstein solutions with Brown-Henneaux asymptotic conditions. A suitable asymptotic expansion shows the agreement of the resulting holographic stress tensor with the one obtained from the auxiliary-field formulation. At the degenerate point, where the two maximally symmetric vacua coalesce, the Fefferman-Graham expansion admits an additional mode associated with relaxed AdS boundary conditions. A quadratic extrinsic counterterm removes the new divergences and leads naturally to a holographic picture with two independent sources. The corresponding responses obey a modified holographic Ward identity and determine finite conserved charges. Finally, the proper use of the Noether-Wald formalism reproduces the correct charges of the BTZ black hole, non-Einstein AdS waves, and the rotating hairy black hole.

We develop a Hopf-algebraic theory of the graph coefficients arising in the quantum Magnus expansion. At the classical level, the graph expansion is governed by directed trees, whereas its quantum counterpart involves loop graphs, multiple edges, and different types of edge data. We introduce a contraction Hopf algebra of mixed quivers containing these physical diagrams and closed under contraction. On the Hopf subalgebra spanned by quivers, we define a character $e$ from normalized linear-extension data and a tadpole prescription, and let $\omega$ be its convolution inverse. Our main result is a universal closed formula for the connected function $\omega_c$ on every finite quiver. The formula is a finite sum over ordered set partitions of the vertex set and is valid without acyclicity or simplicity assumptions. We also give a local characterization: a two-vertex contraction identity, together with tadpole factorization, vanishing on disconnected graphs, and boundary data, determines $\omega_c$ uniquely. For acyclic quivers, the general formula reduces to a permutation formula whose coefficients depend only on descent numbers. We derive the same formula independently from the quantum Magnus expansion via operator products and Wick contractions, showing that its physical graph coefficients are governed by the convolution structure of the contraction Hopf algebra. As further consequences, we obtain a refined quantum Murua formula and orientation-sum identities related to Tutte and chromatic polynomials.

We study linear perturbations of the Maldacena-Milekhin-Popov (MMP) traversable wormhole. On a magnetically charged background, polar metric perturbations couple to axial perturbations of the gauge field. We treat this sector and reduce it to two coupled master equations of Zerilli-Moncrief type. The wormhole has two regions. In the mouths the geometry is a nearly extremal magnetic Reissner-Nordstrom black hole with no quantum source. In the throat the Casimir energy of the lowest Landau level of charged fermions holds the wormhole open. We show that the throat equations are consistent only if the fermions respond to the perturbation, computed exactly from the two-dimensional conformal anomaly with the full stress tensor including the trace part that MMP discard. This response must be accompanied by an induced Hall current of the fermions. With both effects included, the linearised Bianchi identities hold at first order in the fermionic backreaction $\alpha$. Deriving the Hall current from the fermion effective action instead requires an Euler term with coefficient $c/48\pi$, which becomes a coupling between magnetic flux and curvature similar to a Wen-Zee term. At $\alpha=0$ the throat is exact AdS$_2\times S^2$ and the modes decouple into two Poschl-Teller problems with masses $l(l-1)$ and $(l+1)(l+2)$, with levels spaced by $1/\ell$ in frequency. We give the $O(\alpha)$ corrections in closed form. They mix the two modes and depend on frequency, and match the mouths in the overlap region. The symmetric part of the potential is positive throughout the wormhole, excluding purely exponential growth. The corrections lower the normal frequencies and split the levels shared by the two modes, with real shifts at first order in $\alpha$. This sector has no growing mode for $l\ge2$ at this order.

Bell's theorem establishes that a local and spatially separable physical theory with no superdeterminism or retrocausality must be a theory of many local worlds. The local many worlds formalism of quantum mechanics is a transparent separable physical theory in spacetime with a Lorentz covariant causal structure. Unlike the Everett many worlds interpretation, there is no nonseparable universal wavefunction in configuration space, but like Everett, there is only local unitary evolution which conserves probability (fluid) current, and no wavefunction collapse. Each event in spacetime has its own local wavefunction which is built up using only the local wavefunctions and local unitary evolution operators within its past light cone, and which is entirely disconnected from spacelike separated local wavefunctions. We call this the local Schrödinger picture. Local many worlds can also be described in the Heisenberg picture by ascribing Deutsch-Hayden (DH) descriptors to each individual system, each of which evolves under local unitary operations. Both the local wavefunctions and DH descriptors contain records of past interactions, and while the local wavefunctions provide a clear and intuitive physical narrative, the descriptors contain all of the same information in a much more compact form. Unfortunately, the compact form is also somewhat cryptic, which has made the local Heisenberg picture relatively inaccessible. The purpose of this article is to show that the local wavefunctions for any $N$-qubit system can always be constructed directly from the DH descriptors, allowing us to combine the benefits of both pictures.

We study transition amplitudes of the quantum universe in $D$-dimensional spacetime within the de Sitter minisuperspace approximation in Einstein gravity. Using the Lorentzian path integral combined with Picard-Lefschetz theory, we identify the saddle points that contribute to the integral and derive a well-defined transition amplitude under Dirichlet boundary conditions. We further show numerically that a resurgence analysis based on Borel-Padé resummation is effective in resolving the residual Stokes ambiguities that arise in certain cases. Analyzing three-, four-, and five-dimensional cases, as well as the large-$D$ limit, we find that the tunneling proposal is commonly realized for the creation of the universe from nothing. This result implies a universal feature of quantum cosmology based on Einstein gravity across dimensions.

We compute the Higgs thermal mass and the electroweak and colour Debye mass parameters to full $\mathcal{O}(g^6)$ in dimensional reduction, where $g$ represents a gauge coupling or the top Yukawa. We employ new methods to evaluate previously unknown mixed-signature sum-integrals.

It remains an open question whether the modular data $(S,T)$ together with the Whitehead-link matrix $W$ determine a modular tensor category up to ribbon equivalence. We answer negatively by constructing two braided-inequivalent Dijkgraaf–Witten modular categories for $(\mathbb Z/p\mathbb Z)^3$ for prime $p\ge5$ with identical $(S,T,W)$ and, more generally, identical Reshetikhin–Turaev invariants of all framed oriented links with at most two components under a single bijection of simple objects. The construction varies an alternating $3$-cocycle while fixing a quadratic cohomology class, using restriction to subgroups of rank at most two to match link invariants and the quadratic and alternating classes together to obstruct braided equivalence. A complete classification of modular tensor categories up to ribbon equivalence therefore requires invariants beyond those of colored framed links with at most two components. We also analytically evaluate an uncolored partition function on a closed oriented three-manifold that separates all $(p-1)/2$ equivalence classes in the family.

Entanglement harvesting transfers quantum field correlations to localized probes, yet whether these correlations can alter stable strategic behavior has remained unclear. We formulate a quantum-input game in which two Unruh-DeWitt detectors harvest vacuum entanglement from a free massless scalar field in $(3+1)$-dimensional Minkowski spacetime. A referee converts this state into payoffs using independent question qubits and phase-calibrated local Bell measurements. To leading perturbative order, the mean reward is proportional to the signed entanglement margin $\sqrt{\mathcal{H}^2+\mathcal{Q}^2}-\mathcal{P}$, where $\mathcal{H}$ is the Hadamard correlation contribution, $\mathcal{Q}$ is the Pauli-Jordan causal contribution, and $\mathcal{P}$ is the local excitation noise. Away from payoff degeneracies, allowing each player to exit or to choose an early or late interaction yields $1+2n_+$ trembling-hand perfect equilibria, where $n_+$ counts the positive-reward timing equilibria. For one fixed protocol, five analytically certified settings realize the sequence $7\to3\to1\to7\to1$. They represent the spacelike region, the first commutator lobe, central carrier cancellation, the second lobe, and the post-wavefront Huygens regime. Thus, within this fixed quantum-input verification protocol, distinct field-correlation regimes generate different stable strategic structures.

5We study homogeneous cosmological perturbations in the quadratic model $F(R,\mathcal G)=R+\alpha R^2+\beta\mathcal G^2$. Linearization of the modified Friedmann equation together with dust conservation yields a second-order equation for the homogeneous Hubble perturbation, or equivalently a third-order equation for the matter contrast. We then restrict the asymptotic analysis to backgrounds that satisfy the zeroth-order equations of the same quadratic theory. Besides the low-curvature dust branch, which approaches $H=2/(3t)$, the model admits a nontrivial vacuum de Sitter solution with $\beta H_{\rm dS}^6=1/96$. Its homogeneous curvature modes are stable only when $\alpha<-1/(6H_{\rm dS}^2)$. At high curvature the background equation also admits a vacuum big-rip asymptotic branch beginning with $H=7/(t_s-t)$; the first corrections are fixed by the quadratic couplings. The corresponding $\mathcal G^2$-dominated perturbation has one divergent homogeneous mode. The simultaneous Einstein limit is taken only as a consistency check and recovers the standard dust behavior.