The connection between the bulk and the boundary first law of thermodynamics in anti–de Sitter space has been discussed in generic higher derivative gravity. String theory corrections to supergravity render higher derivative terms in the bulk action, proportional to different powers of string theory parameter ${\alpha }^{\prime }$. A variation in the cosmological constant induces a variation in the ’t Hooft coupling in the boundary theory. We show that in order to match the bulk first law and Smarr relation with the boundary side we need to include the variation of ${\alpha }^{\prime }$ in the bulk thermodynamics as a bookkeeping device. Accordingly, the boundary first law and Euler relation are modified with the inclusion of two central charges ($a$, $c$) and/or other chemical potentials as thermodynamic variables. We consider four- and six-derivative terms as well as the ${\text{Weyl}}^4$ terms (in type IIB) in bulk in support of our generic result.

The false vacuum is a metastable state that can occur in quantum field theory, and its decay was first studied semiclassically by Coleman. In this work, we consider the $1+1$ dimensional ${\phi }^4$ theory, which is the simplest model that provides a realization of this problem. We realize the decay as a quantum quench and study the subsequent evolution using a truncated Hamiltonian approach. In the thin wall limit, the decay rate can be described in terms of the mass of the kink interpolating between the vacua in the degenerate limit and the energy density difference between the false and true vacuum once the degeneracy is lifted by a symmetry breaking field, also known as the latent heat. We demonstrate that the numerical simulations agree well with the theoretical prediction for several values of the coupling in a range of the value of the latent heat, apart from a normalization factor, which only depends on the interaction strength.

It is shown that the usual expression for a Feynman diagram in terms of the Feynman propagator ${\mathrm{\Delta }}_F(x-y)$ can be replaced by an equivalent expression involving the positive-energy on-shell propagator ${\mathrm{\Delta }}^{+}(x-y)$, supplemented by appropriate functions associated with time ordering. When this alternate way of expressing a Feynman diagram is Fourier transformed into momentum space, the momentum associated with each function ${\mathrm{\Delta }}^{+}(x-y)$ is on shell, and is only conserved at each vertex if an energy is attributed to the contributions of the time-ordering functions. The resulting expression is analogous to what Kadyshevsky had obtained by deriving an alternate expansion for the $S$ matrix. A detailed explanation of how this alternate expansion is derived is given, and it is shown how it provides a straightforward way of determining the imaginary part of a Feynman diagram, which makes it useful when using unitarity methods for computing a Feynman diagram. By considering a number of specific Feynman diagrams in self-interacting scalar models and in QED, we show how this alternative approach can be related to the old perturbation theory and can simplify direct calculations of Feynman diagrams.

We construct a double copy relation between the Cotton spinor and the dual field strength spinor of topologically massive theories, as the three-dimensional analog of the Weyl double copy. The relationship holds in curved backgrounds for wave solutions. We give an explicit proof for type N spacetimes and show examples satisfying the Cotton double copy.

We apply the recent derivations of dual charges in asymptotically flat spacetimes to asymptotically locally anti–de Sitter (AdS) spacetimes. In contrast to the results in the flat case, in the AdS case with a Dirichlet boundary the dual charge contribution vanishes at the leading order. However, by focusing on the Taub-NUT(Newman-Unti-Tambourino)-AdS solution, we show that, nevertheless, more generally, the dual charge is nonvanishing and corresponds to the NUT parameter. We propose a complex first law of black mechanics in the presence of NUT charges that is inspired by the naturally complex nature of the charges derived using Hamiltonian methods.

Within general relativity, we construct sequences of rapidly rotating Dirac stars consisting of a spinor fluid described by an effective equation of state. We find the physically relevant domain of stable configurations and calculate their principal characteristics which are completely determined by the central density of the spinor fluid, the mass of the nonlinear spinor field, and the velocity of rotation. It is demonstrated that for a certain choice of the spinor field mass, the main physical characteristics of the Dirac stars are close to those that are typical of rotating neutron stars.

Spin precession is a generic feature of compact binary coalescences that leaves clear imprints in the gravitational waveforms. Building on previous work, we present an efficient time domain inspiral-merger-ringdown effective-one-body model for precessing binary black holes, which incorporates subdominant modes beyond $\ell =2$, and the first effective-one-body frequency domain approximant for precessing binary neutron stars. We validate our model against 99 “short” numerical relativity precessing waveforms, where we find median mismatches of $5\times {10}^{-3}$, $7\times {10}^{-3}$ at inclinations of 0, $\pi /3$, and 21 “long” waveforms with median mismatches of $4\times {10}^{-3}$ and $5\times {10}^{-3}$ at the same inclinations. Further comparisons against the state-of-the-art nrsur7dq4 waveform model yield median mismatches of $4\times {10}^{-3}$, $1.8\times {10}^{-2}$ at inclinations of $0,\pi /3$ for 5000 precessing configurations with the precession parameter ${\chi }_p$ up to 0.8 and mass ratios up to 4. To demonstrate the computational efficiency of our model we apply it to parameter estimation and reanalyze the gravitational-wave events GW150914, GW190412, and GW170817.

We investigate the detectability of subdominant spin effects in merging black-hole binaries using current gravitational-wave data. Using a phenomenological model that separates the spin dynamics into precession (azimuthal motion) and nutation (polar motion), we present constraints on the resulting amplitudes and frequencies. We also explore current constraints on the spin morphologies, indicating if binaries are trapped near spin-orbit resonances. We dissect such weak effects from the signals using a sequential prior conditioning approach, where parameters are progressively re-sampled from their posterior distribution. This allows us to investigate whether the data contain additional information beyond what is already provided by quantities that are better measured, namely the masses and the effective spin. For the current catalog of events, we find no significant measurements of weak spin effects such as nutation and spin-orbit locking. We synthesize a source with a high nutational amplitude and show that near-future detections will allow us to place powerful constraints, hinting that we may be at the cusp of detecting spin nutations in gravitational-wave data.

Using the Schwarzschild metric as a rudimentary toy model, we pedagogically revisit the curious prediction that the mass of a classical black hole in a constant temperature thermal bath diverges in a finite amount of time. We study in detail how this instability behaves if the temperature of the bath is allowed to vary with time and conclude that whatever the background behavior (but for a zero-measure subspace of the initial conditions), the black hole mass either diverges or vanishes in a finite time if the Hawking radiation is taken into account. The competition between both effects is subtle and not entirely governed by the hierarchy of the relevant temperatures. This instability is also shown to be reached before the background singularity in a contracting universe, which has implications for bouncing models. The results are generalized to spaces with extra dimensions, and the main conclusions are shown to remain true. The limitations of the model are reviewed, both from the point of view of the dynamical black hole horizon and from the point of view of the background space expansion. Comparisons with other approaches are suggested and possible developments are underlined.

High-accuracy numerical relativity simulations of binary neutron star mergers are a necessary ingredient for constructing gravitational-waveform templates to analyze and interpret observations of compact object mergers. Numerical convergence in the postmerger phase of such simulations is challenging to achieve with many modern codes. In this paper, we study two ways of improving the convergence properties of binary neutron star merger simulations within the Baumgarte-Shapiro-Shibata-Nakamura formulation of Einstein’s equations. We show that discontinuities in a particular constraint damping scheme in this formulation can destroy the postmerger convergence of the simulation. A continuous prescription, in contrast, ensures convergence until late times. We additionally study the impact of the equation of state parametrization on the premerger and postmerger convergence properties of the simulations. In particular, we compare results for a piecewise polytropic parametrization, which is commonly used in merger simulations but suffers unphysical discontinuities in the sound speed, with results using a “generalized” piecewise polytropic parametrization, which was designed to ensure both continuity and differentiability of the equation of state. We report on the differences in the gravitational waves and any spurious premerger heating, depending on which equation of state parametrization is used.

We study the potential for precision electroweak (EW) measurements and beyond-the-Standard Model (BSM) searches using cross-section asymmetries in neutral-current deep inelastic scattering at the electron-ion collider (EIC). Our analysis uses a complete and realistic accounting of systematic errors from both theory and experiment and considers the potential of both proton and deuteron beams for a wide range of energies and luminosities. We also consider what can be learned from a possible future positron beam and a potential tenfold luminosity upgrade of the EIC beyond its initial decade of running. We use the SM effective field theory (SMEFT) framework to parametrize BSM effects and focus on semileptonic four-fermion operators, whereas for our precision EW study, we determine how well the EIC can measure the weak mixing angle. New features of our study include the use of an up-to-date detector design of the EIC Comprehensive Chromodynamics Experiment and accurate running conditions of the EIC, the simultaneous fitting of beam polarization uncertainties and Wilson coefficients to improve the sensitivity to SMEFT operators, and the inclusion of the weak mixing angle running in our fit template. We find that the EIC can probe BSM operators at scales competitive with and in many cases exceeding LHC Drell-Yan bounds while simultaneously not suffering from degeneracies between Wilson coefficients.

We examine effects of $Z^{\prime }$ bosons in gauge-Higgs unification (GHU) models at ${\mathrm{e}}^{+}{\mathrm{e}}^{-}\to {\mathrm{e}}^{+}{\mathrm{e}}^{-}$ Bhabha scatterings. We evaluate differential cross sections in Bhabha scatterings including $Z^{\prime }$ bosons in two types of $\mathrm{SO}(5)\times \mathrm{U}(1)\times \mathrm{SU}(3)$ GHU models. We find that deviations of differential cross sections in the GHU models from those in the SM can be seen at $\sqrt{s}=250\mathrm{GeV}$. With 80%-longitudinally polarized electron and 30%-longitudinally polarized positron beams, the left-right asymmetries in the GHU A and B models are resolved at more than $3\sigma$ at $L_{\mathrm{int}}=250{\mathrm{fb}}^{-1}$. We also show that Bhabha scattering with scattering angle less than 100 mrad can be safely used as luminosity measurements at ${\mathrm{e}}^{+}{\mathrm{e}}^{-}$ colliders since the effects of $Z^{\prime }$ bosons are well suppressed for small scattering angle. We propose a new observable which can be measured at future TeV-scale ${\mathrm{e}}^{+}{\mathrm{e}}^{-}$ linear colliders.

We derive the multicomponent second-order dissipative relativistic hydrodynamic equations using the moment-expansion method. By computing the transport coefficients using hard-sphere interactions, we investigate the role of multiple components and the reactive collisions. We find that both of these factors increase the effective cross section and hence decrease the transport coefficients and relaxation times. We further compute such transport properties using leading-order perturbative QCD cross sections. For both types of cross sections, we find that the ratio between vector current relaxation time and conductivity for a multicomponent fluid is notably different from that for a single-component fluid. Therefore, the current study provides a more applicable guideline for such a ratio in phenomenological hydrodynamics simulations.

A search is presented for heavy bosons decaying to $Z(\nu \overline{\nu })V(q{\overline{q}}^{\prime })$, where $V$ can be a $W$ or a $Z$ boson. A sample of proton-proton collision data at $\sqrt{s}=13\mathrm{TeV}$ was collected by the CMS experiment during 2016–2018. The data correspond to an integrated luminosity of $137{\mathrm{fb}}^{-1}$. The event categorization is based on the presence of high-momentum jets in the forward region to identify production through weak vector boson fusion. Additional categorization uses jet substructure techniques and the presence of large missing transverse momentum to identify $W$ and $Z$ bosons decaying to quarks and neutrinos, respectively. The dominant standard model backgrounds are estimated using data taken from control regions. The results are interpreted in terms of radion, $W^{\prime }$ boson, and graviton models, under the assumption that these bosons are produced via gluon-gluon fusion, Drell–Yan, or weak vector boson fusion processes. No evidence is found for physics beyond the standard model. Upper limits are set at 95% confidence level on various types of hypothetical new bosons. Observed (expected) exclusion limits on the masses of these bosons range from 1.2 to 4.0 (1.1 to 3.7) TeV.

The lattice regularized pure gauge compact U(1) theory is an ideal laboratory to explore how confinement is realized as its phase diagram has a confined and a deconfined phase that depends on the value of the coupling constant, i.e., on $\beta$. Herein, the connection between confinement and positivity violation through the Schwinger function associated with the Landau gauge photon propagator is investigated. The simulations reported show a very clear link between the realization of confinement and positivity violation of the photon Schwinger function and, therefore, of the photon Källén-Lehmann spectral density. Furthermore, a mass scale that characterizes the decay of the Schwinger function for small time separations is computed and used to distinguish the two phases of the theory.

We derive a first-order, stable and causal, relativistic hydrodynamic theory from the microscopic kinetic equation using the gradient expansion technique in a general frame. The general frame is introduced from the arbitrary matching conditions for hydrodynamic fields. The interaction is introduced in the relativistic Boltzmann equation through the momentum-dependent relaxation time approximation (MDRTA) with the proposed collision operator that preserves the conservation laws. We demonstrate here for the first time that not only the general frame choice but also the momentum dependence of microscopic interaction rate, captured through MDRTA, is imperative for producing the essential field corrections that give rise to a causal and stable first-order relativistic theory.

Applying the large $D$ approach to the Einstein-Gauss-Bonnet theory, we construct equally rotating black hole solutions in odd dimensions. This provides the first example of the analytic solutions that describe not-slowly rotating black holes. For the next-to-leading-order solutions in the $1/D$ expansion, we discuss the physical aspects such as thermodynamics and the phase diagram.

In this work, we consider the recently proposed well-defined theory that permits a healthy $D\to 4$ limit of the Einstein-Gauss-Bonnet combination, which requires the addition of a scalar degree of freedom. We continue the construction of exact, hairy black hole solutions in this theory in the presence of matter sources, by considering a nonlinear electrodynamics source, constructed through the Plebański tensor and a precise structural function $\mathcal{H}(P)$. Computing the thermodynamic quantities with the Wald formalism, we identify a region in parameter space where the hairy black holes possess well-defined, nonvanishing, finite thermodynamic quantities, in spite of the relaxed asymptotic approach to planar AdS. We test its local stability under thermal and electrical fluctuations and we also show that a Smarr relation is satisfied for these black hole configurations.

We investigate the long-term orbital dynamics of spinless extended bodies in Schwarzschild geometry, and show that periodic deviations from spherical symmetry in the shape of a test body may trigger the onset of chaos. We do this by applying Dixon’s formalism at quadrupolar order to a nearly spherical body whose shape oscillates between a prolate and an oblate spheroid. The late-time chaotic behavior is then verified by applying Melnikov’s method.

General relativity (GR) exists in different formulations. They are equivalent in pure gravity but generically lead to distinct predictions once matter is included. After a brief overview of various versions of GR, we focus on metric-affine gravity, which avoids any assumption about the vanishing of curvature, torsion, or nonmetricity. We use it to construct an action of a scalar field coupled nonminimally to gravity. It encompasses as special cases numerous previously studied models. Eliminating nonpropagating degrees of freedom, we derive an equivalent theory in the metric formulation of GR. Finally, we give a brief outlook of implications for Higgs inflation.