We present a superconformal master action for a class of supergravity models with one arbitrary function defining the Jordan frame. It leads to a gauge-invariant action for a real vector multiplet, which upon gauge fixing describes a massive vector multiplet, or to a dual formulation with a linear multiplet and a massive tensor field. In both cases the models have one real scalar, the inflaton, naturally suited for single-field inflation. Vectors and tensors required by supersymmetry to complement a single real scalar do not acquire vacuum expectation values during inflation, so there is no need to stabilize the extra scalars that are always present in the theories with chiral matter multiplets. The new class of models can describe any inflaton potential that vanishes at its minimum and grows monotonically away from the minimum. In this class of supergravity models, one can fit any desirable choice of inflationary parameters $n_s$ and $r$.

We demonstrate that the supersymmetry can be dynamically broken even in theories without a Lagrangian. The example we study is the four-dimensional $\mathrm{SU}(N)$ gauge theory coupled to a strongly coupled superconformal theory, called $T_N$, which does not have a Lagrangian description at present. Such a theory without Lagrangians can be analyzed due to the supersymmetry and duality. The model is a direct generalization of the model of supersymmetry breaking on deformed moduli space in supersymmetric QCD with an SU(2) gauge group.

One of the most important characteristics of light in flat spacetime is that it satisfies Huygens’ principle: Initial data for the vacuum Maxwell equations evolve sharply along null (and not timelike) geodesics. In flat spacetime, there are no tails which linger behind expanding wavefronts. Tails generically do exist, however, if the background spacetime is curved. The only nonflat vacuum geometries where electromagnetic fields satisfy Huygens’ principle are known to be those associated with gravitational plane waves. This paper investigates whether perturbations to the plane wave geometry itself also propagate without tails. First-order perturbations to all locally constructed curvature scalars are indeed found to satisfy Huygens’ principles. Despite this, gravitational tails do exist. Locally, they can only perturb one plane wave spacetime into another plane wave spacetime. A weak localized beam of gravitational radiation passing through an arbitrarily strong plane wave therefore leaves behind only a slight perturbation to the waveform of the background plane wave. The planar symmetry of that wave cannot be disturbed by any linear tail. These results are obtained by first deriving the retarded Green function for Lorenz-gauge metric perturbations and then analyzing its consequences for generic initial-value problems.

We compute the one-loop quantum corrections to the potential of ghost-free massive gravity. We show how the mass of external matter fields contributes to the running of the cosmological constant, but does not change the ghost-free structure of the massive gravity potential at one-loop. When considering gravitons running in the loops, we show how the structure of the potential gets destabilized at the quantum level, but in a way which would never involve a ghost with a mass smaller than the Planck scale. This is done by explicitly computing the one-loop effective action and supplementing it with the Vainshtein mechanism. We conclude that to one-loop order the special mass structure of ghost-free massive gravity is technically natural.

Numerical relativity simulations of compact binaries with the Z4c and Baumgarte-Shapiro-Shibata-Nakamura-Oohara-Kojima (BSSNOK) formulations are compared. The Z4c formulation is advantageous in every case considered. In simulations of nonvacuum spacetimes, the constraint violations due to truncation errors are between 1 and 3 orders of magnitude lower in the Z4c evolutions. Improvements are also found in the accuracy of the computed gravitational radiation. For equal-mass irrotational binary neutron star evolutions, we find that the absolute errors in phase and amplitude of the waveforms can be up to a factor of 4 smaller. The quality of the Z4c numerical data is also demonstrated by a remarkably accurate computation of the Arnowitt-Deser-Misner mass from surface integrals. For equal-mass nonspinning binary puncture black hole evolutions, we find that the absolute errors in phase and amplitude of the waveforms can be up to a factor of 2 smaller. In the same evolutions, we find that away from the punctures the Hamiltonian constraint violation is reduced by between 1 and 2 orders of magnitude. Furthermore, the utility of gravitational radiation controlling, constraint preserving boundary conditions for the Z4c formulation is demonstrated. The evolution of spacetimes containing a single compact object confirms earlier results in spherical symmetry. The boundary conditions avoid spurious and nonconvergent effects present in high resolution runs with either formulation with a more naive boundary treatment. We conclude that Z4c is preferable to BSSNOK for the numerical solution of the $3+1$ Einstein equations with the puncture gauge.

We investigate spherical, isothermal and polytropic steady accretion models in the presence of the cosmological constant. Exact solutions are found for three classes of isothermal fluids, assuming the test gas approximation. The cosmological constant damps the mass accretion rate and—above a certain limit—completely stops the steady accretion onto black holes. A “homoclinic-type” accretion flow of polytropic gas has been discovered in anti–de Sitter spacetimes in the test-gas limit. These results can have cosmological connotation, through the Einstein-Straus vacuole model of embedding local structures into Friedman-Lemaitre-Robertson-Walker spacetimes. In particular, one infers that steady accretion would not exist in the late phases of Penrose’s scenario of the evolution of the Universe, known as the Weyl curvature hypothesis.

In a recent paper we investigated stationary, relativistic Bondi-type accretion in Schwarzschild–(anti–)de Sitter spacetimes. Here we study their stability, using the method developed by Moncrief. The analysis applies to perturbations satisfying the potential flow condition. We prove that global isothermal flows in Schwarzschild–anti–de Sitter spacetimes are stable, assuming the test-fluid approximation. Isothermal flows in Schwarzschild–de Sitter geometries and polytropic flows in Schwarzschild–de Sitter and Schwarzschild–anti–de Sitter spacetimes can be stable, under suitable boundary conditions.

We provide an analytic solution to the general wavelength integro-differential equation describing the damping of tensor modes of gravitational waves due to free streaming neutrinos in the early Universe. Our result is expressed as a series of spherical Bessel functions whose coefficients are functions of the reduced wave number $Q$.

We study the mass-radius curve of hybrid stars, assuming a single first-order phase transition between nuclear and quark matter, with a sharp interface between the quark matter core and nuclear matter mantle. We use a generic parametrization of the quark matter equation of state, which has a constant, i.e. density-independent, speed of sound. We argue that this parametrization provides a framework for comparison and empirical testing of models of quark matter. We obtain the phase diagram of possible forms of the hybrid star mass-radius relation, where the control parameters are the transition pressure, energy density discontinuity, and the quark matter speed of sound. We find that this diagram is sensitive to the quark matter parameters but fairly insensitive to details of the nuclear matter equation of state (EoS). We calculate the maximum hybrid star mass as a function of the parameters of the quark matter EoS, and find that there are reasonable values of those parameters that give rise to hybrid stars with mass above $2M_{\odot }$.

Lorentz violation in the weak sector would affect the $\beta$-decay lifetimes of pions. The decay amplitude may be rendered anisotropic, but only an isotropic violation of boost invariance can affect the net lifetime in the center-of-mass frame. However, since the rest frames of the pions that produce the NuMI neutrino beam at Fermilab vary with the rotation of the Earth, it is possible to constrain anisotropic Lorentz violation using prior analyses of sidereal variations in the event rate at the MINOS near detector. The resulting bounds on weak-sector Lorentz violation are at the ${10}^{-4}$ level, a substantial improvement over previous results. The highly relativistic character of the pions involved is responsible for the improvement.

The axion solution to the strong $CP$ problem calls for an explanation as to why the Lagrangian should be invariant under the global Peccei-Quinn (PQ) symmetry, $U(1{)}_{\mathrm{PQ}}$, to such a high degree of accuracy. In this paper, we point out that the $U(1{)}_{\mathrm{PQ}}$ can indeed survive as an accidental symmetry in the low-energy effective theory, if the standard model gauge group is supplemented by a gauged and discrete $R$ symmetry, $Z_N^R$, forbidding all dangerous operators that explicitly break the Peccei-Quinn symmetry. In contrast to similar approaches, the requirement that the $Z_N^R$ symmetry be anomaly-free forces us, in general, to extend the supersymmetric standard model by new matter multiplets. Surprisingly, we find a large landscape of viable scenarios that all individually fulfill the current experimental constraints on the QCD vacuum angle as well as on the axion decay constant. In particular, choosing the number of additional multiplets appropriately, the order $N$ of the $Z_N^R$ symmetry can take any integer value larger than 2. This has interesting consequences with respect to possible solutions of the $\mu$ problem, collider searches for vectorlike quarks and axion dark matter.

We calculate the tensor charge of the quark in the QCD-like theory in the Landau gauge using the Schwinger–Dyson formalism. It is found that the dressed tensor charge of the quark is significantly suppressed against the bare quark contribution, and the result agrees qualitatively with the analyses in the collinear factorization approach and lattice QCD. We also analyze the quark confinement effect with the phenomenological strong coupling given by Richardson and find that this contribution is small. We show that the suppression of the quark tensor charge is due to the superposition of the spin flip of the quark arising from the successive emission of gluons that dress the tensor vertex. We also consider the relation between the quark and the nucleon electric dipole moments by combining with the simple constituent quark model.

We report a measurement of the $D^0$ meson mass using the decay chain $D^{*}(2010{)}^{+}\to D^0{\pi }^{+}$ with $D^0\to K^{-}{K}^{-}{K}^{+}{\pi }^{+}$. The data were recorded with the BABAR detector at center-of-mass energies at and near the $\mathit{{\rm Y}}(4S)$ resonance, and correspond to an integrated luminosity of approximately $477{\mathrm{fb}}^{-1}$. We obtain $m(D^0)=(1864.841\pm 0.048\pm 0.063)\mathrm{MeV}$, where the quoted errors are statistical and systematic, respectively. The uncertainty of this measurement is half that of the best previous measurement.

Gravitomagnetic effects are characterized by two phenomena: first, the geodetic effect which describes the precession of the spin of a gyroscope in a free orbit around a massive object, and second the Lense-Thirring effect which describes the precession of the orbital plane about a rotating source mass. We calculate both these effects in the fourth-order theory of conformal Weyl gravity for the test case of circular orbits. We show that for the geodetic effect a linear term arises which may be interesting for high radial orbits, whereas for the Lense-Thirring effect the additional term has a diminishing effect for most orbits. Circular orbits are also considered in general leading up to a generalization of Kepler’s third law.

We discuss the gravitational dual of a holographic superconductor consisting of a $U(1)$ gauge field, a complex scalar field coupled to a charged AdS black hole and a higher-derivative coupling between the $U(1)$ gauge field and the scalar with coupling constant $\eta$. In the presence of a magnetic field, the system possesses localized spatially dependent droplet solutions which, in the low temperature limit, have smaller critical temperature for $\eta >0$ than the droplet solutions without the interaction term ($\eta =0$). In the weak magnetic field limit, the opposite behavior is observed: the critical temperature increases as we increase $\eta$. We also calculate the energy gap in the probe limit and find that it is larger for $\eta <0$ than the energy gap in the conventional case ($\eta =0$).

We calculate the parametrized post-Newtonian parameters $\gamma$ and $\beta$ for scalar-tensor gravity with a generic coupling function $\omega$ and scalar potential $V$ in the Jordan conformal frame in the case of a static spherically symmetric source. Since the potential generally introduces a radial dependence to the effective gravitational constant as well as to $\gamma$ and $\beta$, we discuss the issue of defining these parametrized post-Newtonian parameters and compare our expressions with previous calculations in simpler cases. We confront our results with current observational constraints on the values of $\gamma$ and $\beta$ and thus draw restrictions on the form of the functions $\omega$ and $V$ around their asymptotic background values.

Based on the new cosmic microwave background temperature data from the Planck satellite, the nine-year polarization data from the Wilkinson Microwave Anisotropy Probe, and the baryon acoustic oscillation distance ratio data from the Sloan Digital Sky Survey and Six-Degree-Field surveys, we place a new constraint on the Brans-Dicke theory. We adopt a parametrization $\zeta =\ln (1+\frac{1}{\omega })$, where the general relativity limit corresponds to $\zeta =0$. We find no evidence of deviation from general relativity. At 95% probability, $-0.00246<\zeta <0.00567$; correspondingly, the region $-407.0<\omega <175.87$ is excluded. If we restrict ourselves to the $\zeta >0$ (i.e., $\omega >0$) case, then the 95% probability interval is $\zeta <0.00549$, corresponding to $\omega >181.65$. We can also translate this result to a constraint on the variation of the gravitational constant and find the variation rate today as $\dot{G}=-{1.42}_{-2.27}^{+2.48}\times {10}^{-13}{\mathrm{yr}}^{-1}$ ($1\sigma$ error bar); the integrated change since the epoch of recombination is $\delta G/G={0.0104}_{-0.0067}^{+0.0186}$ ($1\sigma$ error bar). These limits on the variation of the gravitational constant are comparable with the precision of Solar System experiments.

We study the possibility of testing some generic properties of brane world scenarios at the LHC. In particular, we pay attention to Kaluza-Klein graviton and branon production. Both signals can be dominant depending on the value of the brane tension. We analyze the differences between these two signatures. Finally, we use recent data in the single photon channel from the ATLAS Collaboration to constrain the parameter space of both phenomenologies.