We consider a massless Dirac field in ($1+1$) dimensions, and compute the Tomita-Takesaki modular conjugation corresponding to the vacuum state and a generic multicomponent spacetime region. We do it by analytic continuation from the modular flow, which was computed recently. We use our result to discuss the validity of Haag duality in this model.

Within any anticipated unifying theory of quantum gravity, it should be meaningful to combine the fundamental notions of quantum superposition and spacetime to obtain so-called “spacetime superpositions”: that is, quantum superpositions of different spacetimes not related by a global coordinate transformation. Here we consider the quantum-gravitational effects produced by superpositions of periodically identified Minkowski spacetime (i.e., Minkowski spacetime with a periodic boundary condition) with different characteristic lengths. By coupling relativistic quantum matter to fields on such a spacetime background (which we model using the Unruh-deWitt particle detector model), we are able to show how one can in-principle “measure” the field-theoretic effects produced by such a spacetime. We show that the detector’s response exhibits discontinuous resonances at rational ratios of the superposed periodic length scale.

Center-stabilized $SU(N)$ Yang-Mills theories on ${\mathbb{R}}^3\times S^1$ are QCD-like theories that can be engineered to remain weakly-coupled at all energy scales by taking the $S^1$ circle length $L$ to be sufficiently small. In this regime, these theories admit effective long-distance descriptions as Abelian $U(1{)}^{N-1}$ gauge theories on ${\mathbb{R}}^3$, and semiclassics can be reliably employed to study nonperturbative phenomena such as color confinement and the generation of mass gaps in an analytical setting. At the perturbative tree level, the long-distance effective theory contains ($N-1$) free photons with identical gauge couplings $g_3^2\equiv g^2/L$. Vacuum-polarization effects, from integrating out heavy charged fields, lift this degeneracy to give $\lfloor \frac{N}{2}\rfloor$ distinct values, $g^2(\frac{2}{L})\lesssim g_{3,\ell }^{2}L\lesssim g^2(\frac{2\pi }{NL})$. In this work, we calculate these corrections to one-loop order in theories where the center-symmetric vacuum is stabilized by $2\le n_f\le 5$ massive adjoint Weyl fermions with masses of order $m_{\lambda }\sim \frac{2\pi }{NL}$, (also known as “deformed Yang-Mills,”) and show that our results agree with those found in previous studies in the $m_{\lambda }\to 0$ limit. Then, we show that our result has an intuitive interpretation as the running of the coupling in a “lattice momentum” in the context of the nonperturbative “emergent latticized fourth dimension” in the $N\to \infty$, fixed-$NL$ limit.

We present an analysis on the Becchi-Rouet-Stora-Tyutin (BRST) symmetry transformations of the Hořava theory under the Batalin-Fradkin-Vilkovisky quantization, both in the nonprojectable and projectable cases. We obtain that the BRST transformations are intimately related to a particular spatial diffeomorphism along one of the ghost vector fields. We show explicitly the invariance of the quantum action and the nilpotence of the BRST transformations, using this diffeomorphism largely. The BRST symmetry is verified in the whole phase space, inside and outside the constrained surface. When restricted to the constrained surface, the BRST transformations are completely local. The consistency of the BRST symmetry is a fundamental feature of a quantum field theory, specially for renormalization. The BFV quantization is independent of the chosen gauge-fixing condition. This allows us to study the unitarity of the quantum Hořava theory, covering the gauge required for renormalization. We prove that, if the solution for the lapse function exists, then the unitarity of the theory is established.

Motivated by events in which black holes can lose their environment due to tidal interactions in a binary system, we develop a waveform model in which the tidal deformability interpolates between a finite value (dressed black hole) at relatively low frequency and a zero value (naked black hole) at high frequency. We then apply this model to the example case of a black hole dressed with an ultralight scalar field and investigate the detectability of the tidal Love number with the Einstein Telescope. We show that the parameters of the tidal deformability model could be measured with high accuracy, providing a useful tool to understand dynamical environmental effects taking place during the inspiral of a binary system.

We complete the computation of the gravitational-waveform amplitude for nonspinning compact binaries to the third and a half post-Newtonian (PN) order in the quasicircular case. This is done by performing a spin-weighted spherical harmonics decomposition of the amplitude. This computation is achieved using the post-Newtonian-multipolar-post-Minkowskian formalism. The amplitude modes are written in a PN-expanded way as well as a factorized form suitable for effective-one-body template building. Combining this work with previous ones, we provide in Supplemental Material the expressions of the modes including all nonspinning and spinning effects to the 3.5PN order for nonprecessing quasicircular binaries.

We present a methodology for constructing modified gravity (MG) constrained simulations of the local Universe using positions and peculiar velocities from the CosmicFlows data set. Our analysis focuses on the following MG models: the normal branch of the Dvali-Gabadadze-Porrati (nDGP) model and the Hu-Sawicki $f(R)$ model. We develop a model-independent methodology for constructing constrained simulations with any given power spectra and numerically calculated linear growth functions. Initial conditions (ICs) for a set of constrained simulations are constructed for the standard cosmological model $\mathrm{\Lambda }\mathrm{CDM}$ and the MG models. Differences between the models’ reconstructed Wiener filtered density and the resultant simulation density are presented showing the importance for the generation of MG constrained ICs to study the subtle effects of MG in the local Universe. These are the first MG constrained simulations ever produced. The current work paves the way to improved approximate methods for models with scale-dependent growth functions, such as $f(R)$, and for high-resolution hydrodynamical MG zoom-in simulations of the local Universe.

Features in the primordial power spectrum represent the imprinted signal in the density perturbations of the physics and evolution of the early Universe. A measurement of such signals will represents the need to go beyond the minimal assumption made for the initial conditions of the cosmological perturbations. For the first time, we study different templates with undamped oscillations or a bump from the two-point correlation function measured from BOSS DR12 galaxies constraining the amplitude of the features to be at most a few percent. Constraints are competitive to the ones obtained with Planck DR3.

We propose that the interaction between the axionlike particles (ALPs) and photons can be a possible origin of optical circular polarization (CP) in blazars. Given that there is no definite detection of optical CP at $\sim 0.1\%$ level, a rough limit on ALP-photon coupling can be obtained, specifically $g_{a\gamma }·B_{\mathrm{T}0}\lesssim 7.9\times {10}^{-12}{\mathrm{G}·\mathrm{GeV}}^{-1}$ for $m_a\lesssim {10}^{-13}\mathrm{eV}$, depending on the magnetic field configuration of the blazar jet. Obviously, for the blazar models with a larger magnetic field strength, such as hadronic radiation models, this constraint could be more stringent. We also perform a dedicated analysis of the tentative observations of optical CP in two blazars, namely 3C 66A and OJ 287, and we find that these observations could be explained by the ALP-photon mixing with $g_{a\gamma }\sim {10}^{-11}{\mathrm{GeV}}^{-1}$. As an outlook, our analysis can be improved by further research on the radiation models of blazars and high-precision joint measurements of optical CP and linear polarization.

The phase transition patterns displayed by a model of two coupled complex scalar fields are studied at finite temperature and chemical potential. Possible phenomena like symmetry persistence and inverse symmetry breaking at high temperatures are analyzed. The effect of finite density is also considered and studied in combination with the thermal effects. The nonperturbative optimized perturbation theory method is considered and the results contrasted with perturbation theory. Applications of the results obtained are considered in the context of an effective model for condensation of kaons at high densities, which is of importance in the understanding of the color-flavor locked phase of quantum chromodynamics.

Despite the immense success of the Standard Model (SM), the hunt for physics beyond the Standard Model (BSM) has continued. Extension of the SM gauge group or the particle content of the SM remains a viable solution to many observed anomalies, such as the anomalous magnetic moment of muon, flavor violation, dark matter, etc. In this work, we consider a BSM model which includes a leptoquark, a vectorlike lepton, and a real scalar singlet. The model accounts for a dark matter candidate through a ${\mathbb{Z}}_2$ symmetry in addition to predicting the muon ($g-2$) in agreement with the experimental measurement. We also show that the experimental measurements of the lepton flavor violation are satisfied in a wide range of parameter space. The viable parameter space of the model is used to study the collider signatures arising from the pair production of the leptoquark in the $2\mu +2b+{\cancel{E}}_T$ channel at the 14 TeV LHC run.

Within the effective Lagrangian approach, we carry out a unified study of the $J/\psi ({\psi }^{\prime })\to VP$, $J/\psi \to P\gamma$ and relevant radiative decays of light-flavor hadrons. A large amount of experimental data, including the various decay widths and electromagnetic form factors, is fitted to constrain the numerous hadron couplings. Relative strengths between the strong and electromagnetic interactions are revealed in the $J/\psi \to VP$ and ${\psi }^{\prime }\to VP$ processes. The effect from the strong interaction is found to dominate in the $J/\psi \to \rho \pi$ decay, while the electromagnetic interaction turns out to be the dominant effect in ${\psi }^{\prime }\to \rho \pi$ decay, which provides an explanation to the $\rho \pi$ puzzle. For the $J/\psi \to K^{*}\overline{K}+{\overline{K}}^{*}K$ and ${\psi }^{\prime }\to K^{*}\overline{K}+{\overline{K}}^{*}K$, the former process is dominated by the strong interactions, and the effects from the electromagnetic parts are found to be comparable with those of strong interactions in the latter process. Different $SU(3)$ breaking effects from the electromagnetic parts appear in the charged and neutral channels for the ${\psi }^{\prime }\to K^{*}\overline{K}+{\overline{K}}^{*}K$ processes explain the rather different ratios between $B({\psi }^{\prime }\to K^{*+}{K}^{-}+K^{*-}{K}^{+})/B(J/\psi \to K^{*+}{K}^{-}+K^{*-}{K}^{+})$ and $B({\psi }^{\prime }\to K^{*0}{\overline{K}}^0+{\overline{K}}^{*0}{K}^0)/B(J/\psi \to K^{*0}{\overline{K}}^0+{\overline{K}}^{*0}{K}^0)$.

We calculate the strong decay couplings for $\rho \to \pi \pi$, $\varphi \to KK$, $K^{*}\to K\pi$, and $D^{*}\to D\pi$ in a unified and consistent approach based on the impulse approximation, nonperturbative solutions of the quark-gap equation and the Poincaré invariant Bethe-Salpeter amplitudes of vector and pseudoscalar mesons. In particular, we obtain the coupling $g_{D^{*}D\pi }=17.24_{-2.30}^{+3.06}$ in very good agreement with the experimental value by CLEO, which corresponds to a strong effective coupling between heavy vector and pseudoscalar mesons to the pion of $\widehat{g}=0.58_{-0.08}^{+0.10}$.

We measure the ratio of branching fractions for the $\mathrm{\Upsilon }(4S)$ decays to $B^{+}{B}^{-}$ and $B^0{\overline{B}}^0$ using $B^{+}\to J/\psi (\ell \ell )K^{+}$ and $B^0\to J/\psi (\ell \ell )K^0$ samples, where $J/\psi (\ell \ell )$ stands for $J/\psi \to {\ell }^{+}{\ell }^{-}$ ($\ell =e$ or $\mu$), with $711{\mathrm{fb}}^{-1}$ of data collected at the $\mathrm{\Upsilon }(4S)$ resonance with the Belle detector. We find the decay rate ratio of $\mathrm{\Upsilon }(4S)\to B^{+}{B}^{-}$ over $\mathrm{\Upsilon }(4S)\to B^0{\overline{B}}^0$ to be $1.065\pm 0.012\pm 0.019\pm 0.047$, which is the most precise measurement to date. The first and second uncertainties are statistical and systematic, respectively, and the third uncertainty is due to the assumption of isospin symmetry in $B\to J/\psi (\ell \ell )K$.

We analytically compute the out-of-equilibrium direct photon-production rate and electric conductivity, in a strongly coupled and expanding Bjorken plasma, from holography. Our results are valid at late times where the expanding plasma asymptotes Bjorken hydrodynamics. The out-of-equilibrium rates are substantially harder and larger, early on in the Bjorken expansion phase.

The phase space formulation of double field theory (DFT) indicates that statistical matter can be included in terms of ($T$-)duality multiplets. We propose the inclusion of a perfect fluid in the geometry of DFT through a generalized energy-momentum tensor written in terms of a DFT pressure, energy density, and velocity. The latter is an $O(D,D)$ vector and satisfies two invariant constraints in agreement with the on-shell constraints for the generalized momentum. We compute the conservation laws associated to the energy-momentum tensor considering general DFT backgrounds. Then we study cosmological backgrounds and we find an expression for the DFT cosmological dynamics with the perfect fluid coupled. This proposal reproduces the equations of string cosmology with nontrivial fixed dilaton charge upon parametrization of the DFT Einstein equations.

We introduce a saddle-point finder that can find the complex saddle points for any analytically continued action. We showcase our saddle-point finder by two examples in the EPRL spin foam model: the single vertex case and the case of triangulation ${\mathrm{\Delta }}_3$. In both cases, the complex saddle points are found, and each saddle point’s contribution to the partition function is estimated. We also discuss the geometrical interpretation of each saddle point.

The estimation of radiative modes is a central problem in gravitational wave theory, with essential applications in signal modeling and data analysis. This problem is complicated by most astrophysically relevant systems not having modes that are analytically tractable. A ubiquitous workaround is to use not modes, but multipole moments defined by spin-weighted spherical harmonics. However, spherical multipole moments are only related to the modes of systems without angular momentum. As a result, they can obscure the underlying physics of astrophysically relevant systems, such as binary black hole merger and ringdown. In such cases, spacetime angular momentum means that radiative modes are not spherical, but spheroidal in nature. Here, we work through various problems related to spheroidal harmonics. We show for the first time that spheroidal harmonics are not only capable of representing arbitrary gravitational wave signals, but that they also possess a kind of orthogonality not used before in general relativity theory. Along the way we present a new class of spin-weighted harmonic functions dubbed “adjoint-spheroidal” harmonics. These new functions may be used for the general estimation of spheroidal multipole moments via complete biorthogonal decomposition (in the angular domain). By construction, adjoint-spheroidal harmonics suppress mode-mixing effects known to plague spherical harmonic decomposition; as a result, they better approximate a system’s true radiative modes. We discuss potential applications of these results. Lastly, we briefly comment on the challenges posed by the analogous problem with Teukolsky’s radial functions.

Contrary to a prevailing assumption that black holes would swiftly discharge, we argue that black holes can charge preferentially when boosted through an ambient magnetic field. Though the details are very different, the preference for charge is related to the precipitation of the Wald charge on a spinning black hole in an ambient magnetic field. The gravitoelectrodynamics upstage naive arguments about screening electric fields—in vacuum—in determining the value of the charge accrued. Charged test particles, which build up the black hole charge, exhibit chaotic behavior as evidenced by fractal basin boundaries between dynamical regions. Charged, boosted black holes will generate their own electromagnetic fields and thereby their own luminous signatures, even if they are initially bare. We therefore add boosted black holes to the growing list of potentially observable black hole signatures, alongside black hole batteries and black hole pulsars. The implications should be relevant for supermassive black holes that are boosted relative to a galactic magnetic field as well as black holes merging with magnetized neutron stars.