Tensor hierarchy of exceptional field theories contains gauge fields satisfying certain Bianchi identities. We define the full set of fluxes of the SL(5) exceptional field theory containing known gauge field strengths, generalized anholonomy coefficients and two new fluxes. It is shown that the full SL(5) ExFT Lagrangian can be written in terms of the listed fluxes. We derive the complete set of Bianchi identities and identify magnetic potentials of the theory and the corresponding (wrapped) membranes of M-theory.

Recent work by Danielson, Satishchandran, and Wald (DSW) has shown that black holes—and, in fact, Killing horizons more generally—impart a fundamental rate of decoherence on all nearby quantum superpositions. The effect can be understood from measurement and causality: An observer (Bob) in the black hole should be able to disturb outside quantum superpositions by measuring their superposed gravitational fields, but since his actions cannot (by causality) have this effect, the superpositions must automatically disturb themselves. DSW calculated the rate of decoherence up to an unknown numerical factor for distant observers in Schwarzschild spacetime, Rindler observers in flat spacetime, and static observers in de Sitter spacetime. Working in electromagnetic and Klein-Gordon analogs, we flesh out and generalize their calculation to derive a general formula for the precise decoherence rate for Killing observers near bifurcate Killing horizons. We evaluate the rate in closed form for an observer at an arbitrary location on the symmetry axis of a Kerr black hole. This fixes the numerical factor in the distant-observer Schwarzschild result, while allowing new exploration of near-horizon and/or near-extremal behavior. In the electromagnetic case we find that the decoherence vanishes entirely in the extremal limit, due to the “black hole Meissner effect” screening the Coulomb field from entering the black hole. This supports the causality picture: Since Bob is unable to measure the field of the outside superposition, no decoherence is necessary—and indeed none occurs.

We consider a four-dimensional $SU(N_c)$ gauge theory coupled to $N_f$ species of color fermions and $N_f^2$ colorless scalars. The quantum field theory possesses a weakly interacting ultraviolet fixed point that we determine from beta functions computed up to four-loop order in the gauge coupling, and up to three-loop order in the Yukawa and quartic scalar couplings. The fixed point has one relevant direction giving rise to asymptotic safety. We compute fixed-point values of dimensionless couplings together with the corresponding scaling exponents up to the first three nontrivial orders in Veneziano parameter $\epsilon$, both for infinite and finite number of colors $N_c$. We also consider anomalous dimensions for fields, scalar mass squared, and a class of dimension-three operators. Contrary to previous studies, we take into account possible mixing of the latter and compute eigenvalues of the corresponding matrix. Further, we investigate the size of the conformal window in the Veneziano limit and its dependence on $N_c$.

In this paper we analyze higher Schwarzians and show that they are closely related to the nonlinear realization of the Virasoro algebra. The Goldstone fields of such a realization provide a new set of $SL(2,\mathbb{R})$ invariant higher Schwarzians that are deeply related to those of Aharonov [Duke Math. J. 36, 599 (1969)], Tamanoi [Math. Ann. 305, 127 (1996)], and Bonora-Matone [Nucl. Phys. B327, 415 (1989); Int. J. Mod. Phys. A 10, 289 (1995); arXiv:hep-th/9306150]. A minor change of the coset space parametrization leads to a new set of $SL(2,\mathbb{R})$ noninvariant higher Schwarzians now related to the Schippers [Proc. Am. Math. Soc. 128, 3241 (2000)] and Bertilsson [Ark. Mat. 36, 255 (1998)] Schwarzians.

The recent increasing interest in detecting gravitational waves (GWs) by lunar seismic measurement urges us to have a clear understanding of the response of the moon to passing GWs. In this paper, we clarify the relationship between two seemingly different response functions which have been derived previously using two different methods, one taking the field-theory approach and the other using the tidal force induced by GWs. We revisit their derivation and prove, by both analytical arguments and numerical calculations, that the two response functions are equivalent. Their apparent difference can be attributed to the choice of different coordinates. Using the correct response function, we calculate the sensitivities (to GWs) of several designed lunar seismometers, and find that the sensitivity curves between ${10}^{-3}$ and 0.1 Hz are much flatter than the previous calculations based on normal-mode model. Our results will help clarify the scientific objectives of lunar GW observation, as well as provide important constraints on the design of lunar GW detectors.

Higher-order scalar-tensor theories having an instantaneous mode do not develop the Ostrogradsky instability even if a seemingly dangerous mode is present. Such theories satisfy only partially the degeneracy conditions that are usually imposed to remove the dangerous mode completely, and are dubbed as unitary degenerate higher-order scalar-tensor (U-DHOST) theories. We study weak gravitational fields sourced by nonrelativistic matter distributions in U-DHOST theories. In contrast to the case of totally degenerate theories where nonlinear derivative interactions are crucial for exhibiting the Vainshtein mechanism and its partial breaking, we show that in generic U-DHOST theories the linear analysis is sufficient for weak gravitational fields. We identify the subset of U-DHOST theories in which solar system tests are evaded and gravitational waves propagate at the speed of light. Such theories can however be tested with cosmological observations. We also point out that there is a particular case of U-DHOST theories where nonlinear derivative interactions play an important role as in totally degenerate theories. In that case, it is found, however, that the Vainshtein mechanism does not operate and gravitational forces are modified.

Despite having important cosmological implications, the reheating phase is believed to play a crucial role in both cosmology and particle physics model building. Conventional reheating models primarily rely on arbitrary coupling between the inflaton and massless fields, which lacks robust predictions. In this article, we propose a novel reheating mechanism where the particle physics model, namely, the type-I seesaw model, is shown to play a major role in the entire reheating process, and the inflaton is assumed to be free from arbitrary coupling. To the best of our knowledge, this is the first reheating model of its kind that, besides being successful in resolving the well-known neutrino mass and baryon asymmetry problems, constrains a large class of inflation models, offers successful reheating, and predicts a distinct primordial gravitational-wave spectrum and nonvanishing lowest active neutrino mass. Our novel mechanism opens up a new avenue of integrating particle physics and cosmology in the context of reheating.

We study a screening mechanism in the context of scalar-vector-tensor (SVT) theories. This screening mechanism is based on both the derivative self-interactions of the vector field and the interactions of the scalar field with the vector field and curvature. We calculate the field equations in a spherically symmetric space-time, and then, we study the conditions for which this mechanism is successful in a weak gravitational background. In order to corroborate these analytical results, we have performed a numerical integration of the full equations. Finally, the corrections to the gravitational potentials have also been computed. We conclude that the present model, including both kinds of interactions, can avoid the propagation of the additional longitudinal mode arising in these theories. We also show that the space parameter of the model is compatible with solar system constraints. This result extends the previous one found in the literature for generalized Proca theories to the case of SVT theories in the presence of scalar-vector interactions.

We investigate the production of nonthermal dark matter (DM), $\chi$, during the postinflationary reheating era. For inflation, we consider two slow roll single field inflationary scenarios—generalized version of Hilltop (GH) inflation, and Coleman-Weinberg (CW) inflation. Using a set of benchmark values that comply with the current constraints from cosmic microwave background radiation (CMBR) data for each inflationary model, we explored the parameter space involving mass of dark matter particles, $m_{\chi }$, and coupling between inflaton and $\chi$, $y_{\chi }$. For these benchmarks, we find that tensor-to-scalar ratio $r$ can be as small as $2.69\times {10}^{-6}$ for GH and $1.91\times {10}^{-3}$ for CW inflation, both well inside $1\text{−}\sigma$ contour on scalar spectral index versus $r$ plane from Planck2018+BICEP3+Keck Array2018 dataset, and testable by future cosmic microwave background (CMB) observations, e.g., Simons Observatory. For the production of $\chi$ from the inflaton decay satisfying CMB and other cosmological bounds and successfully explaining total cold dark matter density of the present universe, we find that $y_{\chi }$ should be within this range $\mathcal{O}({10}^{-4})\gtrsim y_{\chi }\gtrsim \mathcal{O}({10}^{-20})$ for both inflationary scenarios. We also show that, even for the same inflationary scenario, the allowed parameter space on reheating temperature versus $m_{\chi }$ plane alters with inflationary parameters including scalar spectral index, $r$, and energy scale of inflation.

Electrons and positrons produced in dark matter annihilation can generate secondary emission through synchrotron and inverse Compton (IC) processes, and such secondary emission provides a possible means to detect dark matter (DM) particles with masses beyond the detector’s energy band. The secondary emission of heavy dark matter (HDM) particles in the TeV-PeV mass range lies within the Fermi-LAT energy band. In this paper, we utilize the Fermi-LAT observations of dwarf spheroidal (dSph) galaxies to search for annihilation signals of HDM particles. We consider the propagation of $e^{+}/e^{-}$ produced by DM annihilation within the dSphs, derive the electron spectrum of the equilibrium state by solving the propagation equation, and then compute the gamma-ray signals produced by the $e^{+}/e^{-}$ population through the IC and synchrotron processes. Considering the spatial diffusion of electrons, the dSphs are modeled as extended sources in the analysis of Fermi-LAT data according to the expected spatial intensity distribution of the gamma rays. We do not detect any significant HDM signal. By assuming a magnetic field strength of $B=1\mathrm{\mu }\mathrm{G}$ and a diffusion coefficient of $D_0=3\times {10}^{28}{\mathrm{cm}}^2{\mathrm{s}}^{-1}$ of the dSphs, we place limits on the annihilation cross section for HDM particles. Our results are weaker than the previous limits given by the VERITAS and IceCube observations of dSphs, but extend the existing limits to higher DM masses. As a complement, we also search for the prompt $\gamma$ rays produced by DM annihilation and give limits on the cross section in the $10–{10}^5\mathrm{GeV}$ mass range. Consequently, in this paper we obtain the upper limits on the DM annihilation cross section for a very wide mass range from 10 GeV to 100 PeV in a unified framework of the Fermi-LAT data analysis.

The $B$-mesogenesis framework anticipates decays of $B$ mesons into a dark antibaryon $\mathrm{\Psi }$ and various Standard Model baryons. Here, we focus on the exclusive decay process $B\to p\mathrm{\Psi }$ observed as a proton and missing energy in the final state and determine the decay width by employing the QCD light-cone sum rule framework. We include all contributions up to twist six to the nucleon distribution amplitudes in order to parametrize the nonperturbative effects in the operator product expansion. We obtain the decay width and branching fraction with respect to the mass $m_{\mathrm{\Psi }}$ of the dark antibaryon $\mathrm{\Psi }$.

In this work, we delve into the often overlooked cosmological implications of the spontaneous breaking of the non-Abelian discrete groups, specifically focusing on the formation of domain walls in the case of $S_4$ flavor symmetry. In particular, we investigate three interesting breaking patterns of the $S_4$ group and study the structure of the domain walls in the broken phase for three possible residual symmetries. The presentation of domain walls in the case of multiple vacua is usually complicated, which therefore implies that most of the analyses only approximate their presentation. Here, we propose a subtle way to represent the $S_4$ domain wall networks by presenting the vacua in each breaking pattern as vectors with their components corresponding to their coordinates in the flavon space. Then, through the properties of the obtained vectors, we find that the domain wall networks can be represented by Platonic or Archimedean solids where the vertices represent the degenerate vacua while the edges correspond to the domain walls that separate them. As an illustration, we propose a type-II seesaw model that is based on the $S_4$ flavor symmetry, and study its phenomenological implications on the neutrino sector. To solve the domain wall problem within this toy model, we consider an approach based on high-dimensional effective operators induced by gravity that explicitly break the structure of the induced vacua favoring one vacuum over the others.

We investigate the effects of anomalous neutral triple gauge couplings in $ZZ$ and $Z\gamma$ production processes, followed by the leptonic decay of the $Z$ boson, at a lepton collider with center-of-mass energy $\sqrt{s}=250\mathrm{GeV}$ and polarized beams. We use an effective Lagrangian formalism to parametrize the anomalous couplings in terms of dimension-8 operators $c_{\tilde{B}W}$, $c_{BW}$, $c_{WW}$, and $c_{BB}$, and study the sensitivity of observables such as cross section, polarization, and spin correlation as functions of these couplings. We perform a Bayesian statistical analysis using Markov Chain Monte Carlo methods to determine simultaneous limits on the anomalous couplings, taking into account various luminosities $\mathcal{L}\in \{0.1{\mathrm{ab}}^{-1},0.3{\mathrm{ab}}^{-1},1{\mathrm{ab}}^{-1},3{\mathrm{ab}}^{-1},10{\mathrm{ab}}^{-1}\}$ and systematic uncertainties. We find that polarization and spin correlation observables significantly enhance the sensitivity to anomalous couplings, providing stringent constraints on these couplings.

Motivated by attempts to quantum simulate lattice models with continuous Abelian symmetries using discrete approximations, we study an extended-O(2) model in two dimensions that differs from the ordinary O(2) model by the addition of an explicit symmetry breaking term $-h_q\cos (q\phi )$. Its coupling $h_q$ allows to smoothly interpolate between the O(2) model ($h_q=0$) and a $q$-state clock model ($h_q\to \infty$). In the latter case, a $q$-state clock model can also be defined for noninteger values of $q$. Thus, such a limit can also be considered as an analytic continuation of an ordinary $q$-state clock model to noninteger $q$. In previous work, we established the phase diagram for noninteger $q$ in the infinite coupling limit ($h_q\to \infty$). We showed that there is a second-order phase transition at low temperature and a crossover at high temperature. In this work, we seek to establish the phase diagram at finite values of the coupling using Monte Carlo and tensor methods. We show that for noninteger $q$, the second-order phase transition at low temperature and crossover at high temperature persist to finite coupling. For integer $q=2$, 3, 4, we know there is a second-order phase transition at infinite coupling (i.e. the well-known clock models). At finite coupling, we find that the critical exponents for $q=3$, 4 vary with the coupling, and for $q=4$ the transition may turn into a Berezinskii-Kosterlitz-Thouless transition at small coupling. We comment on the similarities and differences of the phase diagrams with those of quantum simulators of the Abelian-Higgs model based on ladder-shaped arrays of Rydberg atoms.

We show that volume-preserving diffeomorphisms and the chemical shift symmetry defining relativistic Lagrangian ideal fluid dynamics can be derived as an emerging symmetry when ergodicity is assumed to apply locally in a way that is invariant under smooth spacetime foliations. This can be used as a way to derive the ideal hydrodynamic limit in a strongly coupled but strongly fluctuating medium. We comment on the connection with thermalization in small systems, the eigenstate thermalization hypothesis and deviations from the ideal limit.

Quantum focusing is a powerful conjecture that plays a key role in the current proofs of many well-known quantum gravity theorems, including various consistency conditions, and causality constraints in $\mathrm{AdS}/\mathrm{CFT}$. We conjecture a (weaker) restricted quantum focusing, which we argue is sufficient to derive all known essential implications of quantum focusing. Subject to a technical assumption, we prove this conjecture in braneworld semiclassical gravity theories that are holographically dual to Einstein gravity in a higher-dimensional anti–de Sitter spacetime.

We find the entanglement entropy of a subregion of the vacuum state in scalar quantum electrodynamics, working perturbatively to the two-loop level. Doing so leads us to derive the Maxwell-Proca propagator in conical Euclidean space. The area law of entanglement entropy is recovered in both the massive and massless limits of the theory, as is expected. These results yield the renormalization group flow of entanglement entropy, and we find that loop contributions suppress entanglement entropy. We highlight these results in the light of the renormalization group flow of couplings and correlators, which are increased in scalar quantum electrodynamics, so that the potential tension between the increase in correlations between two points of spacetime and the decrease in entanglement entropy between two regions of spacetime with energy is discussed. We indeed show that the vacuum of a subregion of spacetime purifies with energy in scalar quantum electrodynamics, which is related to the concept of screening.

This paper continues the investigation initiated in Cho et al. [Quantum capacity and vacuum compressibility of spacetime: Thermal fields, Universe 8, 291 (2022)] into the quantum thermodynamic properties of space by deriving the vacuum compressibility of a variety of dynamical spacetimes containing massive and massless conformally coupled quantum fields. The quantum processes studied here include particle creation, Casimir effect, and the trace anomaly. The spaces include $S^2$, $S^3$, and $T^3$ with prescribed time evolution and $S^1$, where the temporal development is backreaction determined. Vacuum compressibility belongs to the same group of quantum thermodynamic/mechanical response functions as vacuum viscosity, a concept first proposed in 1970 by Zel’dovich [Particle production in cosmology, Pis’ma Zh. Eksp. Teor. Fiz. 12, 443 (1970)] for capturing the effects of vacuum particle production on the dynamics of the early Universe, made precise by the rigorous work of many authors in the following decade using quantum field theory in curved spacetime methodologies and semiclassical gravity theory for treating backreaction effects. Various subtleties in understanding the behavior of the vacuum energies of quantum field origins, negative pressures and novel complicated features of dynamical compressibility are discussed.

We investigate the quantum signature of gravity in optomechanical systems under quantum control. We analyze the gravity-induced entanglement and squeezing in mechanical mirrors in a steady state. The behaviors and the conditions for generating the gravity-induced entanglement and squeezing are identified in the Fourier modes of the mechanical mirrors. The condition of generating the entanglement between the mirrors found in the present paper is more severe than that of the gravity-induced entanglement between output lights. The gravity-induced entanglement in optomechanical systems is an important milestone toward verifying the quantum nature of gravity, which should be verified in the future.

Recently, Fernandes discovered analytic stationary and axially symmetric black hole solutions within semiclassical gravity, driven by the trace anomaly. The study unveils some distinctive features of these solutions. In this paper, we compute the gravitational waves emitted from the extreme-mass-ratio inspiral (EMRI) around these quantum-corrected rotating black holes using the kludge approximate method. First, we derive the orbital energy, angular momentum, and fundamental frequencies for orbits on the equatorial plane. We find that, for the gravitational radiation described by quadrupole formulas, the contribution from the trace anomaly only appears at higher-order terms in the energy flux when compared with the standard Kerr case. Therefore, we can compute the EMRI waveforms from the quantum-corrected rotating black hole using the Kerr fluxes. We assess the differences between the EMRI waveforms from rotating black holes with and without the trace anomaly by calculating the dephasing and mismatch. Our results demonstrate that space-borne gravitational wave detectors can distinguish the EMRI waveform from the quantum-corrected black holes with a fractional coupling constant of $\sim {10}^{-3}$ within one year observation. Finally, we compute the constraint on the coupling constant using the Fisher information matrix method and find that the potential constraint on the coupling constant by LISA can be within the error $\sim {10}^{-4}$ in suitable scenarios.