We present the results of 61 new simulations of nonprecessing spinning black hole binaries with mass ratios $q=m_1/m_2$ in the range $1/3\le q\le 1$ and individual spins covering the parameter space $-0.85\le {\alpha }_{1,2}\le 0.85$. We additionally perform ten new simulations of nonspinning black hole binaries with mass ratios covering the range $1/6\le q<1$. We follow the evolution for typically the last ten orbits before merger down to the formation of the final remnant black hole. This allows for assessment of the accuracy of our previous empirical formulas for relating the binary parameters to the remnant final black hole mass, spin and recoil. We use the new simulation to improve the fit to the above remnant formulas and add a formula for the peak luminosity of gravitational waves, produced around the merger of the two horizons into one. We find excellent agreement (typical errors $\sim 0.1\%–0.2\%$) for the mass and spin, and within $\sim 5\%$ for the recoil and peak luminosity. These formulas have direct application to parameter estimation techniques applied to LIGO observations of gravitational waves from binary black hole mergers.

The covariant understanding of dispersion relations as level sets of Hamilton functions on phase space enables us to derive the most general dispersion relation compatible with homogeneous and isotropic spacetimes. We use this concept to present a Planck-scale deformation of the Hamiltonian of a particle in Friedman-Lemaître-Robertson-Walker (FLRW) geometry that is locally identical to the $\kappa$-Poincaré dispersion relation, in the same way as the dispersion relation of point particles in general relativity is locally identical to the one valid in special relativity. Studying the motion of particles subject to such a Hamiltonian, we derive the redshift and lateshift as observable consequences of the Planck-scale deformed FLRW universe.

We analyze the mode stability of odd-parity perturbations of black holes with linearly time-dependent scalar hair in shift-symmetric Horndeski theories. We show that a large class of black hole solutions in these theories suffer from ghost or gradient instability, while there are some classes of solutions that are stable under linear odd-parity perturbations in the context of mode analysis.

The phantom brane has several important distinctive features: (i) Its equation of state is phantomlike, but there is no future “big rip” singularity, and (ii) the effective cosmological constant on the brane is dynamically screened, because of which the expansion rate is smaller than that in $\mathrm{\Lambda }\mathrm{CDM}$ at high redshifts. In this paper, we constrain the Phantom braneworld using distance measures such as type-Ia supernovae (SNeIa), baryon acoustic oscillations (BAO), and the compressed cosmic microwave background (CMB) data. We find that the simplest braneworld models provide a good fit to the data. For instance, $\mathrm{BAO}+\mathrm{SNeIa}$ data can be accommodated by the braneworld for a large region in parameter space $0\le {\mathrm{\Omega }}_{\ell }\lesssim 0.3$ at $1\sigma$. The Hubble parameter can be as high as $H_0\lesssim 78\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$, and the effective equation of state at present can show phantomlike behavior with $w_0\lesssim -1.2$ at $1\sigma$. We note a correlation between $H_0$ and $w_0$, with higher values of $H_0$ leading to a lower, and more phantomlike, value of $w_0$. Inclusion of CMB data provides tighter constraints ${\mathrm{\Omega }}_{\ell }\lesssim 0.1$. (Here ${\mathrm{\Omega }}_{\ell }$ encodes the ratio of the five- and four-dimensional Planck mass.) The Hubble parameter in this case is more tightly constrained to $H_0\lesssim 71\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$, and the effective equation of state to $w_0\lesssim -1.1$. Interestingly, we find that the Universe is allowed to be closed or open, with $-0.5\lesssim {\mathrm{\Omega }}_{\kappa }\lesssim 0.5$, even on including the compressed CMB data. There appears to be some tension in the low and high-$z$ BAO data which may either be resolved by future data, or act as a pointer to interesting new cosmology.

We investigate scalar particle creation in a set of bouncing models where the bounce occurs due to quantum cosmological effects described by the Wheeler-DeWitt equation. The scalar field can be either conformally or minimally coupled to gravity, and it can be massive or massless, without self-interaction. The analysis is made for models containing a single radiation fluid and for the more realistic case of models containing the usual observed radiation and dust fluids, which can fit most of the observed features of our universe, including an almost scale invariant power spectrum of scalar cosmological perturbations. In the conformal coupling case, the particle production is negligible. In the minimal coupling case, for massive particles, the results point to the same physical conclusion within observational constraints: particle production is most important at the bounce energy scale, and it is not sensitive either to its mass or to whether there is dust in the background model. The only caveat is the case where the particle mass is larger than the bounce energy scale. On the other hand, the energy density of produced massive particles depend on their masses and the energy scale of the bounce. For very large masses and deep bounces, this energy density may overcome that of the background. In the case of massless particles, the energy density of produced particles can become comparable to the background energy density only for bounces occurring at energy scales comparable to the Planck scale or above, which lies beyond the scope of this paper: we expect that the simple Wheeler-DeWitt approach we are using should be valid only at scales a few orders of magnitude below the Planck energy. Nevertheless, in the case in which dust is present, there is an infrared divergence, which becomes important only for scales much larger than today’s Hubble radius.

Clusters of galaxies have the potential of providing powerful constraints on possible deviations from General Relativity. We use the catalog of Sunyaev-Zel’dovich (SZ) sources detected by Planck and consider a correction to the halo mass function for a $f(R)$ class of modified gravity models, which has been recently found to reproduce well results from $N$-body simulations, to place constraints on the scalaron field amplitude at the present time, $f_R^0$. We find that applying this correction to different calibrations of the halo mass function produces upper bounds on $f_R^0$ tighter by more than an order of magnitude, ranging from ${\log }_{10}(-f_R^0)<-5.81$ to ${\log }_{10}(-f_R^0)<-4.40$ (95% confidence level). This sensitivity is due to the different shape of the halo mass function, which is degenerate with the parameters used to calibrate the scaling relations between SZ observables and cluster masses. Any claim of constraints more stringent that the weaker limit above, based on cluster number counts, appears to be premature and must be supported by a careful calibration of the halo mass function and by a robust calibration of the mass scaling relations.

We examine some of the roots of parity violation for gravitons and uncover a closely related new effect: correlations between right- and left-handed gravitons. Such correlators have spin 4 if they involve gravitons moving along the same direction and spin zero for gravitons moving with opposite directions. In the first case, the most immediate implication would be a degree of linear polarization for the tensor vacuum fluctuations, which could be seen by gravity-wave detectors sensitive enough to probe the primordial background, its degree of polarization and anisotropies. Looking at the anisotropy of the gravity waves linear polarization, we identify the parity respecting and violating components of the effect. The imprint on the cosmic microwave background temperature and polarization would be more elusive, since it averages to zero in the two-point functions, appearing only in their cosmic variance or in fourth-order correlators. In contrast, spin-zero correlations would have an effect on the two-point function of the cosmic microwave background temperature and polarization, enhancing the $BB$ component if they were anticorrelations. Such correlations represent an amplitude for the production of standing waves, as first envisaged by Grishchuk, and could also leave an interesting signature for gravity-wave detectors.

We calculate the metric and affine connection due to a piecewise linear cosmic string loop, and the effect of gravitational backreaction for the Garfinkle-Vachaspati loop with four straight segments. As expected, backreaction reduces the size of the loop, in accord with the energy going into gravitational waves. The “square” (maximally symmetric) loop evaporates without changing shape, but for all other loops in this class, the kinks become less sharp and segments between kinks become curved. If the loop is close to the square case, it will evaporate before its kinks are significantly changed; if it is far from square, the opening out of the kinks is much faster than evaporation of the loop.

We study the neutrino flavor evolution in the neutrino-driven wind from a binary neutron star merger remnant consisting of a massive neutron star surrounded by an accretion disk. With the neutrino emission characteristics and the hydrodynamical profile of the remnant consistently extracted from a three-dimensional simulation, we compute the flavor evolution by taking into account neutrino coherent forward scattering off ordinary matter and neutrinos themselves. We employ a “single-trajectory” approach to investigate the dependence of the flavor evolution on the neutrino emission location and angle. We also show that the flavor conversion in the merger remnant can affect the (anti)neutrino absorption rates on free nucleons and may thus impact the $r$-process nucleosynthesis in the wind. We discuss the sensitivity of such results on the change of neutrino emission characteristics, also from different neutron star merger simulations.

Observations indicate that ordinary matter, the baryons, influence the structural properties of dark matter on galactic scales. One such indication is the radial acceleration relation, which is a tight correlation between the measured gravitational acceleration and that expected from the baryons. We show here that the dark matter density profile that has been motivated by dissipative dark matter models, including mirror dark matter, can reproduce this radial acceleration relation.

Astrophysical tests of the stability of fundamental couplings are becoming an increasingly important probe of new physics. Motivated by the recent availability of new and stronger constraints we update previous works testing the consistency of measurements of the fine-structure constant $\alpha$ and the proton-to-electron mass ratio $\mu =m_p/m_e$ (mostly obtained in the optical/ultraviolet) with combined measurements of $\alpha$, $\mu$ and the proton gyromagnetic ratio $g_p$ (mostly in the radio band). We carry out a global analysis of all available data, including the 293 archival measurements of Webb et al. and 66 more recent dedicated measurements, and constraining both time and spatial variations. While nominally the full data sets show a slight statistical preference for variations of $\alpha$ and $\mu$ (at up to two standard deviations), we also find several inconsistencies between different subsets, likely due to hidden systematics and implying that these statistical preferences need to be taken with caution. The statistical evidence for a spatial dipole in the values of $\alpha$ is found at the 2.3 sigma level. Forthcoming studies with facilities such as ALMA and ESPRESSO should clarify these issues.

A common feature of many string-motivated particle physics models is additional strongly coupled $U(1)$’s. In such sectors, electric and magnetic states have comparable mass, and integrating out modes also charged under $U(1)$ hypercharge generically yields $CP$ preserving electric kinetic mixing and $CP$ violating magnetic kinetic mixing terms. Even though these extra sectors are strongly coupled, we show that in the limit where the extra sector has approximate $\mathcal{N}=2$ supersymmetry, we can use formal methods from Seiberg-Witten theory to compute these couplings. We also calculate various quantities of phenomenological interest such as the cross section for scattering between visible sector states and heavy extra sector states as well as the effects of supersymmetry breaking induced from coupling to the minimal supersymmetric Standard Model.

We investigate the interparticle potential between spin-0, spin-$1/2$, and spin-1 sources interacting in modified electrodynamics in the nonrelativistic regime. By keeping terms of $\mathcal{O}(|\mathbf{p}{|}^2/m^2)$ in the amplitudes, we obtain spin- and velocity-dependent interaction energies. We find well-known effects such as spin-orbit couplings, as well as spin-spin (dipole-dipole) interactions. For concreteness, we consider the cases of electrodynamics with higher derivatives (Podolsky-Lee-Wick) and hidden photons.

The Georgi-Machacek model extends the Standard Model Higgs sector with the addition of isospin-triplet scalar fields in such a way as to preserve the custodial symmetry. The presence of higher-isospin scalars contributing to electroweak symmetry breaking offers the interesting possibility that the couplings of the 125 GeV Higgs boson to both gluons and vector boson pairs could be larger than those of the Standard Model Higgs boson. Constraining this possibility using measurements of Higgs production and decay at the CERN Large Hadron Collider is notoriously problematic if a new, non–Standard Model decay mode of the 125 GeV Higgs boson is present. We study an implementation of this scenario in which the Georgi-Machacek model is extended by a real singlet scalar dark matter candidate, and require that the singlet scalar account for all the dark matter in the Universe. The combination of the observed dark matter relic density and direct-detection constraints exclude singlet scalar masses below about 57 GeV. Higgs measurements are not yet precise enough to be very sensitive to $h\to SS$ in the remaining allowed kinematic region, so that constraints from Higgs measurements are so far the same as in the GM model without a singlet scalar. We also find that, above the Higgs pole, a substantial region of parameter space yielding the correct dark matter relic density can escape the near-future direct-detection experiments DEAP and XENON 1T for dark matter masses as low as 120 GeV and even have a direct-detection cross section below the neutrino floor for $m_S\gtrsim 150\mathrm{GeV}$. This is in contrast to the singlet scalar dark matter extension of the Standard Model, for which these future experiments are expected to exclude dark matter masses above the Higgs pole up to the multi-TeV range.

We propose a mechanism for the enhancement of vacuum fluctuations by means of a classical field. The basic idea is that if an observable quantity depends quadratically upon a quantum field, such as the electric field, then the application of a classical field produces a cross term between the classical and quantum fields. This cross term may be significantly larger than the purely quantum part, but also undergoes fluctuations driven by the quantum field. We illustrate this effect in a model for light-cone fluctuations involving pulses in a nonlinear dielectric. Vacuum electric field fluctuations produce fluctuations in the speed of a probe pulse, and form an analog model for quantum gravity effects. If the material has a nonzero third-order susceptibility, then the fractional light speed fluctuations are proportional to the square of the fluctuating electric field. Hence the application of a classical electric field can enhance the speed fluctuations. We give an example where this enhancement can be an increase of 1 order of magnitude, increasing the possibility of observing the effect.

We study the feasibility of probing a region of natural supersymmetry where the stop and Higgsino masses are compressed. Although this region is most effectively searched for in the monojet channel, this signature is present in many other nonsupersymmetric frameworks. Therefore, another channel that carries orthogonal information is required to confirm the existence of the light stop and Higgsinos. We show that a supersymmetric version of the $t\overline{t}H$ process, $pp\to t{\tilde{t}}_1{\tilde{\chi }}_{1(2)}^0$, can have an observably large rate when both the stop and Higgsinos are significantly light, and it leads to a distinctive monotop signature in the compressed mass region. We demonstrate that the hadronic channel of the monotop signature can effectively discriminate the signal from backgrounds by tagging a hadronic top jet. We show that the hadronic channel of the monotop signature offers a significant improvement over the leptonic channel and the sensitivity reaches $m_{{\tilde{t}}_1}\simeq 420\mathrm{GeV}$ at the 13 TeV LHC with $3{\mathrm{ab}}^{-1}$ luminosity.