We derive the scalar waveform generated by a binary of nonspinning compact objects (black holes or neutron stars) in a general class of scalar-tensor theories of gravity. The waveform is accurate to 1.5 post-Newtonian order [$O((v/c{)}^3)$] beyond the leading-order tensor gravitational waves (the “Newtonian quadrupole”). To solve the scalar-tensor field equations, we adapt the direct integration of the relaxed Einstein equations formalism developed by Will, Wiseman, and Pati. The internal gravity of the compact objects is treated with an approach developed by Eardley. We find that the scalar waves are described by the same small set of parameters which describes the equations of motion and tensor waves. For black hole–black hole binaries, the scalar waveform vanishes, as expected from previous results which show that these systems in scalar-tensor theory are indistinguishable from their general relativistic counterparts. For black hole–neutron star binaries, the scalar waveform simplifies considerably from the generic case, essentially depending on only a single parameter up to first post-Newtonian order. With both the tensor and scalar waveforms in hand, we calculate the total energy flux carried by the outgoing waves. This quantity is computed to first post-Newtonian order relative to the “quadrupole formula” and agrees with previous, lower order calculations.

We study Weitzenböck’s torsion and discuss its properties. Specifically, we calculate the measured components of Weitzenböck’s torsion tensor for a frame field adapted to static observers in a Fermi normal coordinate system that we establish along the world line of an arbitrary accelerated observer in general relativity. A similar calculation is carried out in the standard Schwarzschild-like coordinates for static observers in the exterior Kerr spacetime; we then compare our results with the corresponding curvature components. Our work supports the contention that in the extended general relativistic framework involving both the Levi-Civita and Weitzenböck connections, curvature and torsion provide complementary representations of the gravitational field.

We study the asymptotically flat rotating hairy black hole solution of a three-dimensional gravity theory which is given by taking the flat-space limit (zero cosmological constant limit) of new massive gravity. We propose that the dual field theory of the flat-space limit of new massive gravity can be described by a contracted conformal field theory which is invariant under the action of the ${\mathrm{BMS}}_3$ group. Using the flat/contracted conformal field theory correspondence, we construct a stress tensor which yields the conserved charges of the asymptotically flat black hole solution. We check that our expressions of the mass and angular momentum fit with the first law of black hole thermodynamics. Furthermore, by taking the appropriate limit of the Cardy formula in the parent conformal field theory, we find a Cardy-like formula which reproduces the Wald’s entropy of the 3D asymptotically flat black hole.

The conservative dynamics of gravitationally interacting two-point-mass systems has been recently determined at the fourth post-Newtonian (4PN) approximation [T. Damour, P. Jaranowski, and G. Schäfer, Phys. Rev. D 89, 064058 (2014)], and found to be nonlocal in time. We show how to transcribe this dynamics within the effective one-body (EOB) formalism. To achieve this EOB transcription, we develop a new strategy involving the (infinite-)order-reduction of a nonlocal dynamics to an ordinary action-angle Hamiltonian. Our final, equivalent EOB dynamics comprises two (local) radial potentials, $A(r)$ and $\overline{D}(r)$, and a nongeodesic mass-shell contribution $Q(r,p_r)$ given by an infinite series of even powers of the radial momentum $p_r$. Using an effective action technique, we complete our 4PN-level results by deriving two different, higher-order conservative contributions linked to tail-transported hereditary effects: the 5PN-level EOB logarithmic terms, as well as the 5.5PN-level, half-integral terms. We compare our improved analytical knowledge to previous, numerical gravitational-self-force computation of precession effects.

We investigate instabilities of classical Yang-Mills fields in a time-dependent spatially homogeneous color magnetic background field in a nonexpanding geometry for elucidating the earliest stage dynamics of ultrarelativistic heavy-ion collisions. The background field configuration considered in this article is spatially homogeneous and temporally periodic and is introduced by Berges-Scheffler-Schlichting-Sexty (BSSS). We discuss the whole structure of instability bands of fluctuations around the BSSS background gauge field on the basis of Floquet theory, which enables us to discuss the stability in a systematic way. We find various instability bands on the $(p_z,p_T)$ plane. These instability bands are caused by parametric resonance despite the fact that the momentum dependence of the growth rate for $|\mathbf{p}|\le \sqrt{B}$ is similar to a Nielsen-Olesen instability. Moreover, some of the instability bands are found to emerge not only in the low-momentum but also in the high-momentum region, typically of the order of the saturation momentum as $|\mathbf{p}|\sim \sqrt{B}\sim Q_{\mathrm{s}}$.

We consider minimal modifications to the tribimaximal (TBM) mixing matrix which accommodate nonzero mixing angle ${\theta }_{13}$ and $CP$ violation. We derive four possible forms for the minimal modifications to TBM mixing in a model with $A_4$ flavor symmetry by incorporating symmetry breaking terms appropriately. We show how possible values of the Dirac-type $CP$ phase ${\delta }_D$ can be predicted with regards to two neutrino mixing angles in the standard parametrization of the neutrino mixing matrix. Carrying out a numerical analysis based on the recent updated experimental results for neutrino mixing angles, we predict the values of the $CP$ phase for all possible cases. We also confront our predictions for the $CP$ phase with the updated fit.

In the type I seesaw model, the naturalness requirement that corrections to the electroweak $\mu$ parameter not exceed 1 TeV results in a rough bound on the lightest right-handed neutrino mass, $M_{N_1}\lesssim 3\times 10^7\mathrm{GeV}$. In this paper we derive generic bounds applicable in any three-flavor type I seesaw model. We find $M_{N_1}\lesssim 4\times 10^7\mathrm{GeV}$ and $M_{N_2}\lesssim 7\times 10^7\mathrm{GeV}$. In the limit of one massless neutrino, there is no naturalness bound on $M_{N_3}$ in the Poincaré protected decoupling limit. Our results confirm that no type I seesaw model can explain the observed neutrino masses and baryogenesis via hierarchical ($N_1$-, $N_2$-, or $N_3$-dominated) thermal leptogenesis while remaining completely natural.

A search for neutron-antineutron ($n-\overline{n}$) oscillation was undertaken in Super-Kamiokande using the 1489 live-day or $2.45\times {10}^{34}$ neutron-year exposure data. This process violates both baryon and baryon minus lepton numbers by an absolute value of two units and is predicted by a large class of hypothetical models where the seesaw mechanism is incorporated to explain the observed tiny neutrino masses and the matter-antimatter asymmetry in the Universe. No evidence for $n-\overline{n}$ oscillation was found; the lower limit of the lifetime for neutrons bound in ${}^{16}\mathrm{O}$, in an analysis that included all of the significant sources of experimental uncertainties, was determined to be $1.9\times {10}^{32}\mathrm{years}$ at the 90% confidence level. The corresponding lower limit for the oscillation time of free neutrons was calculated to be $2.7\times {10}^8\mathrm{s}$ using a theoretical value of the nuclear suppression factor of $0.517\times {10}^{23}{\mathrm{s}}^{-1}$ and its uncertainty.

A search is presented for the decay $\mathrm{\Upsilon }(1S)\to \gamma A^0$, $A^0\to c\overline{c}$, where $A^0$ is a candidate for the $CP$-odd Higgs boson of the next-to-minimal supersymmetric standard model. The search is based on data collected with the BABAR detector at the $\mathrm{\Upsilon }(2S)$ resonance. A sample of $\mathrm{\Upsilon }(1S)$ mesons is selected via the decay $\mathrm{\Upsilon }(2S)\to {\pi }^{+}{\pi }^{-}\mathrm{\Upsilon }(1S)$. The $A^0\to c\overline{c}$ decay is identified through the reconstruction of hadronic $D^0$, $D^{+}$, and $D^{*}(2010{)}^{+}$ meson decays. No significant signal is observed. The measured 90% confidence-level upper limits on the product branching fraction $\mathcal{B}(\mathrm{\Upsilon }(1S)\to \gamma A^0)\times \mathcal{B}(A^0\to c\overline{c})$ range from $7.4\times {10}^{-5}$ to $2.4\times {10}^{-3}$ for $A^0$ masses from 4.00 to $8.95\mathrm{GeV}/c^2$ and 9.10 to $9.25\mathrm{GeV}/c^2$, where the region between 8.95 and $9.10\mathrm{GeV}/c^2$ is excluded because of background from $\mathrm{\Upsilon }(2S)\to \gamma {\chi }_{bJ}(1P)$, ${\chi }_{bJ}(1P)\to \gamma \mathrm{\Upsilon }(1S)$ decays.

In this paper we use two different but complementary approaches in order to study the ghost propagator of a pure SU(3) Yang-Mills theory quantized in the linear covariant gauges, focusing on its dependence on the gauge-fixing parameter $\xi$ in the deep infrared. In particular, we first solve the Schwinger-Dyson equation that governs the dynamics of the ghost propagator, using a set of simplifying approximations, and under the crucial assumption that the gluon propagators for $\xi >0$ are infrared finite, as is the case in the Landau gauge $(\xi =0)$. Then we appeal to the Nielsen identities, and express the derivative of the ghost propagator with respect to $\xi$ in terms of certain auxiliary Green’s functions, which are subsequently computed under the same assumptions as before. Within both formalisms we find that for $\xi >0$ the ghost dressing function approaches zero in the deep infrared, in sharp contrast to what happens in the Landau gauge, where it is known to saturate at a finite (nonvanishing) value. The Nielsen identities are then extended to the case of the gluon propagator, and the $\xi$-dependence of the corresponding gluon masses is derived using as input the results obtained in the previous steps. The result turns out to be logarithmically divergent in the deep infrared; the compatibility of this behavior with the basic assumption of a finite gluon propagator is discussed, and a specific Ansatz is put forth, which readily reconciles both features.

We study ferromagnetism at high density of neutrons in the QCD hadron phase, by using the simplest chiral effective model incorporating magnetic fields and the chiral anomaly. Under the assumption of spatial homogeneity, we calculate the energy density as a function of neutron density, with a magnetization and a neutral pion condensation in the style of Dautry and Neyman. We find that at a high density the energy of the ferromagnetic order is lower than that of the ordinary neutron matter, and the reduction effect is enhanced by the anomaly. Compared to the inhomogeneous phase with the alternating layer structure, our ferromagnetic phase turns out to be unfavored. However, once an axial vector meson condensation is taken into account in our simplest model, the ferromagnetic energy density is lowered significantly, which still leaves some room for a possible realization of a QCD ferromagnetic phase and ferromagnetic magnetars.

We study the influence of a background uniform magnetic field and boundary conditions on the vacuum of a quantized charged spinor matter field confined between two parallel neutral plates; the magnetic field is directed orthogonally to the plates. The admissible set of boundary conditions at the plates is determined by the requirement that the Dirac Hamiltonian operator be self-adjoint. It is shown that, in the case of a sufficiently strong magnetic field and a sufficiently large separation of the plates, the generalized Casimir force is repulsive, being independent of the choice of a boundary condition, as well as of the distance between the plates. The detection of this effect seems to be feasible in the foreseeable future.

In this work, we show that it is possible to study the notion of a geodesic deviation equation in $f(T)$ gravity, in spite of the fact that in teleparallel gravity there is no notion of geodesics, and the torsion is responsible for the appearance of gravitational interaction. In this regard, we obtain the general relativity equivalent equations for $f(T)$ gravity, which are in the modified gravity form such as $f(R)$ gravity. Then, we obtain the geodesic deviation equation within the context of this modified gravity. In this way, the obtained geodesic deviation equation will correspond to the $f(T)$ gravity. Eventually, we extend the calculations to obtain the modification of the Mattig relation.

The presence of a scalar field that couples nonminimally and universally to matter can enhance gravitational forces on cosmological scales while restoring general relativity in the Solar neighborhood. In the intermediate regime, kinematically inferred masses experience an additional radial dependence with respect to the underlying distribution of matter, which is caused by the increment of gravitational forces with increasing distance from the Milky Way center. The same effect can influence the internal kinematics of subhalos and cause cuspy matter distributions to appear core-like. Specializing to the chameleon model as a worked example, we demonstrate this effect by tracing the scalar field from the outskirts of the Milky Way halo to its interior, simultaneously fitting observed velocity dispersions of chemo-dynamically discriminated red giant populations in the Fornax and Sculptor dwarf spheroidals. Whereas in standard gravity these observations suggest that the matter distribution of the dwarfs is cored, we find that in the presence of a chameleon field the assumption of a cuspy Navarro-Frenk-White profile becomes perfectly compatible with the data. Importantly, chameleon models also predict the existence of slopes between two stellar subcomponents that in Newtonian gravity would be interpreted as a decline of matter density toward the dwarf center. Hence, an observation of such an apparently pathological scenario may serve as a smoking gun for the presence of a chameleon field or a similar modification of gravity, independent of baryonic feedback effects. In general, measuring the dynamic mass profiles of the Milky Way dwarfs provides stronger constraints than those inferred from the screening scale of the Solar System since these are located at greater distances from the halo center.

We present examples of non-Gaussian statistics that can induce bispectra matching local and nonlocal (including equilateral) templates in biased subvolumes. We find cases where the biasing from coupling to long wavelength modes affects only the power spectrum, only the bispectrum or both. Our results suggest that ruling out multifield scenarios is quite difficult: some measurements of the scalar correlations, including the shape of the bispectrum, can be consistent with single-clock predictions even when cosmic variance from super-horizon modes is at work. Furthermore, if observations of the density perturbations rule out single-clock inflation, we will face a serious cosmic variance obstacle in drawing any further conclusions about the particle physics origin of the scalar fluctuations.

Dark matter (DM) annihilation or decay can affect the anisotropy of the cosmic microwave background (CMB). Therefore, the CMB data can be used to constrain the properties of a dark matter particle. In this work, we use the new CMB data obtained by the Planck satellite to investigate the limits on the basic parameters of a dark matter particle. The parameters are the dark matter mass ($m_{\chi }$) and the thermally averaged cross section ($⟨\sigma v⟩$) for dark matter annihilation and the decay rate ($\mathrm{\Gamma }$) (or lifetime $\tau =1/\mathrm{\Gamma }$) for dark matter decay. For dark matter annihilation, we also consider the impact of the structure formation process which is neglected by the recent work. We find that for DM annihilation, the constraints on the parameters are $f_{ann}=⟨\sigma v⟩/m_{\chi }<0.16\times 10^{-26}{\mathrm{cm}}^3{\mathrm{s}}^{-1}{\mathrm{GeV}}^{-1}$(or $f_{ann}<0.89\times 10^{-6}{\mathrm{m}}^3{\mathrm{s}}^{-1}{\mathrm{kg}}^{-1}$, 95% C.L.). For DM decay, the constraints on the decay rate are $\mathrm{\Gamma }<0.28\times 10^{-25}{\mathrm{s}}^{-1}$(95% C.L.).

We propose a model for large field inflation in heterotic string theory. The construction applies the near alignment mechanism of Kim, Nilles, and Peloso. By including gaugino condensates and world-sheet instanton nonperturbative effects, we obtain a large effective axion decay constant.

We investigate the impact on the classical dynamics of dark matter particles and dark energy of a nonminimal coupling in the dark sector, assuming that the mass of the dark matter particles is coupled to a dark energy scalar field. We show that standard results can be recovered only if the space-time variation of the dark energy scalar field is sufficiently smooth on the characteristic length scale of the dark matter particles, and we determine the associated constraint dependent on both the mass and radius of the dark matter particles and the coupling to the dark energy scalar field. We further show, using field theory numerical simulations, that a violation of such constraint results in a microscopic feedback effect strongly affecting the dynamics of dark matter particles, with a potential impact on structure formation and on the space-time evolution of the dark energy equation of state.

In this paper we continue to develop the $m$-mode formalism, a technique for efficient and optimal analysis of wide-field transit radio telescopes, targeted at 21 cm cosmology. We extend this formalism to give an accurate treatment of the polarized sky, fully accounting for the effects of polarization leakage and cross polarization. We use the geometry of the measured set of visibilities to project down to pure temperature modes on the sky, serving as a significant compression, and an effective first filter of polarized contaminants. As in our previous work, we use the $m$-mode formalism with the Karhunen-Loève transform to give a highly efficient method for foreground cleaning, and demonstrate its success in cleaning realistic polarized skies observed with an instrument suffering from substantial off axis polarization leakage. We develop an optimal quadratic estimator in the $m$-mode formalism which can be efficiently calculated using a Monte Carlo technique. This is used to assess the implications of foreground removal for power spectrum constraints where we find that our method can clean foregrounds well below the foreground wedge, rendering only scales $k_{\parallel }<0.02h{\mathrm{Mpc}}^{-1}$ inaccessible. As this approach assumes perfect knowledge of the telescope, we perform a conservative test of how essential this is by simulating and analyzing data sets with deviations about our assumed telescope. Assuming no other techniques to mitigate bias are applied, we find we recover unbiased power spectra when the per-feed beamwidth to be measured to 0.1%, and amplifier gains to be known to 1% within each minute. Finally, as an example application, we extend our forecasts to a wideband 400–800 MHz cosmological observation and consider the implications for probing dark energy, finding a pathfinder-scale medium-sized cylinder telescope improves the Dark Energy Task Force figure of merit by around 70% over Planck and Stage II experiments alone.