We investigate the pion scalar form factor in the Meiman-Okubo framework, implementing the phase below the inelastic $K\overline{K}$ threshold, where it is known from the $\pi \pi$ scalar isoscalar phase shift ${\delta }_0^0$ by Watson theorem. State-of-the-art knowledge of the perturbative QCD expansion of the scalar correlator and the phase shift ${\delta }_0^0$ is used as input. No assumptions about the phase above the inelastic threshold or the possible zeros of the form factor in the complex plane are necessary. We obtain a model-independent constraint relating the sum of the light quark masses to the slope and the curvature of the pion scalar form factor at the origin. The recent lattice results for the light quark masses and the pion scalar radius are found to satisfy this constraint. We obtain also a strong correlation between the pion scalar radius and the curvature of the form factor, with rather high values predicted for the curvature.

We analyze the constraints on models of WIMP dark matter that can be derived from upper bounds on the “monojet” cross section at the LHC. These constraints were originally interpreted in the context of an effective field theory (EFT) where the Standard Model is extended by a dimension-6 operator whose coefficient is $1/{\mathrm{\Lambda }}^2$. We show that combining the 8 TeV data of the ATLAS and CMS collaborations improves the bounds only slightly. We then analyze this final state in the context of simplified models with an $s$-channel mediator. We show that if the decay width of the mediator is small, these simplified models can be accurately modeled by the effective field theory only if the mediator mass is above 5 TeV. Finally, we point out that even if the EFT accurately describes the $\mathcal{O}({\mathrm{\Lambda }}^{-2})$ contributions to the matrix element, for values of $\mathrm{\Lambda }$ near the current bound it receives significant contributions of order ${\mathrm{\Lambda }}^{-4}$; in the context of simplified models, these correspond to diagrams where two mediators are exchanged. This observation challenges the internal consistency of the EFT description since dimension-8 operators, which would also contribute to $\mathcal{O}({\mathrm{\Lambda }}^{-4})$ to the matrix element, are not included.

We study the LHC sensitivity to a $W^{\prime }$ produced via bottom and charm quarks and decaying to $\tau$ flavor leptons in the mass range 200–1000 GeV. We show that the extra $b$ quarks necessitated by the production mechanism can improve the background rejection compared to an inclusive analysis relying solely on $\tau$ tagging and $E_T^{\mathrm{miss}}$. We present prospective limits on the couplings and compare them to the best fit to the $R(D^{(*)})$ anomalies in $B$-meson decays.

We investigate the possibility that both dark matter and the long-standing discrepancy in the anomalous magnetic moment of the muon may be explained within the minimal supersymmetric standard model. In light of the stringent bounds from direct detection, we argue that the most promising viable scenarios have bino-like dark matter produced via either bino-wino or bino-slepton coannihilation. We find that the combination of next-generation direct detection experiments and the LHC will be able to probe much of the interesting parameter space; however a future high-energy collider is needed to comprehensively explore this scenario.

In this paper we investigate, by means of numerical lattice simulations, the topological properties of the trace deformed $SU(3)$ Yang-Mills theory defined on $S_1\times {\mathbb{R}}^3$. More precisely, we evaluate the topological susceptibility and the $b_2$ coefficient (related to the fourth cumulant of the topological charge distribution) of this theory for different values of the lattice spacing and of the compactification radius. In all the cases we find results in good agreement with the corresponding ones of the standard $SU(3)$ Yang-Mills theory on ${\mathbb{R}}^4$.

Using 5326 days of atmospheric neutrino data, a search for atmospheric tau neutrino appearance has been performed in the Super-Kamiokande experiment. Super-Kamiokande measures the tau normalization to be $1.47\pm 0.32$ under the assumption of normal neutrino hierarchy, relative to the expectation of unity with neutrino oscillation. The result excludes the hypothesis of no-tau appearance with a significance level of $4.6\sigma$. The inclusive charged-current tau neutrino cross section averaged by the tau neutrino flux at Super-Kamiokande is measured to be $(0.94\pm 0.20)\times {10}^{-38}{\mathrm{cm}}^2$. The measurement is consistent with the Standard Model prediction, agreeing to within $1.5\sigma$.

The tunneling wave function of the universe is investigated in a minisuperspace framework of a de Sitter universe with a quantum scalar field, treated as a perturbation. We consider three different approaches to defining the tunneling wave function: (1) tunneling boundary conditions in superspace, (2) Lorentzian path integral, and (3) quantum tunneling from initial universe of a vanishing size. We show that the superspace approach requires Robin boundary conditions for the scalar field modes, the path integral approach requires adding an appropriate boundary term to the scalar field action, and the initial universe approach requires the initial quantum state of the scalar field to be Euclidean vacuum. We find that all three approaches yield identical wave functions and that scalar field fluctuations are well behaved, contrary to earlier claims in the literature.

Gravitational waves from spin-precessing binaries exhibit amplitude oscillations that provide an invaluable method to extract the spins of the inspiraling compact objects. The spin-spin and spin-orbit interactions that cause this effect are sensitive to the fundamental nature of gravity, which will allow us to constrain modified theories of gravity using gravitational wave observations of precessing binaries. We here consider precessing black hole binaries in dynamical Chern-Simons gravity, an effective theory of gravity that enhances parity violating interactions. We model the black holes as modified point particles using effective field theory, and derive the spin-precession equations for a binary system by working within the post-Newtonian formalism. We find that the spin-spin and quadrupole-monopole interactions of general relativity are modified due to an interaction between the scalar dipoles of the two black holes and the modified black hole quadrupole as a result of the violation of the no hair theorems. These modifications enter the precession equations at leading post-Newtonian order. We further show that these precession equations admit seven constants of motion when neglecting radiation reaction, with only the mass-weighted effective spin being modified from general relativity. We discuss how these may be used to reduce the precession equations to quadrature and the possibility of constructing analytic Fourier domain waveforms for generic spin-precessing binaries in dCS gravity.

It has been shown that the presence of nonminimally coupled scalar fields giving rise to a fifth force can noticeably alter dynamics on galactic scales. Such a fifth force must be screened in the Solar System but if unscreened it can have similar observational effects as a component of nonbaryonic matter. We consider this possibility in the context of the vertical motions of local stars in the Milky Way disk by reframing a methodology used to measure the local density of dark matter. By attempting to measure the properties of the symmetron field required to support vertical velocities we can test it as a theory of modified gravity and understand the behavior of screened scalar fields in galaxies. In particular, this relatively simple setup allows the symmetron field profile to be solved for model parameters where the equation of motion becomes highly nonlinear and difficult to solve in other contexts. We update the existing Solar System constraints for this scenario and find a region of parameter space not already excluded that can explain the vertical motions of local stars out to heights of 1 kpc. At larger heights the force due to the symmetron field profile exhibits a characteristic turn over which would allow the model to be distinguished from a dark matter halo.

We demonstrate an all-sky search for persistent, narrowband gravitational waves using mock data. The search employs radiometry to sidereal-folded data in order to uncover persistent sources of gravitational waves with minimal assumptions about the signal model. The method complements continuous-wave searches, which are finely tuned to search for gravitational waves from rotating neutron stars, while providing a means of detecting more exotic sources that might be missed by dedicated continuous-wave techniques. We apply the algorithm to simulated Gaussian noise. We project the strain amplitude sensitivity assuming circularly polarized signals for the LIGO network in the first observing run to be $h_0\approx 1.2\times {10}^{-24}$ (1% false alarm probability, 10% false dismissal probability). We include a treatment of instrumental lines and detector artifacts using time-shifted LIGO data from the first observing run.

We consider the problem of gravitational deflection of propagating relativistic massive particles by rotating black holes (Kerr black holes) and rotating wormholes (Teo wormholes) in the weak limit approximation. In particular, we have introduced an alternative way to calculate the deflection angle for massive particles based on the refractive index of the optical media and the Gauss-Bonnet theorem applied to the isotropic optical metrics. The refraction index governing the propagation of massive particles is calculated by considering those particles as de Broglie wave packets. Finally, applying the Gauss-Bonnet theorem leads to an exact result for the deflection angle in both geometries. Put in other words, the trajectory of light rays as well as the trajectory of massive particles in a given spacetime background can be viewed as a global spacetime effect, namely, as a topological effect.

Generic massive gravity models in the unitary gauge correspond to a self-gravitating medium with six degrees of freedom (d.o.f.). It is widely believed that massive gravity models with six d.o.f. have an unavoidable ghostlike instability; however, the corresponding medium has stable phononlike excitations. The apparent contradiction is solved by the presence of a nonvanishing background pressure and energy density of the medium that opens up a stability window. The result is confirmed by looking at linear stability on an expanding Universe, recovering the flat space stability conditions in the small wavelength limit. Moreover, one can show that under rather mild conditions, no ghostlike instability is present for any wavelength. As a result, exploiting the medium interpretation, a generic massive gravity model with six d.o.f. is perfectly viable.

One of the most common consequences of extensions to the standard models of particle physics or cosmology is the emergence of a fifth force. While generic fifth forces are tightly constrained at Solar System scales and below, they may escape detection by means of a screening mechanism which effectively removes them in dense environments. We constrain the strength $\mathrm{\Delta }G/G_N$ and range ${\lambda }_C$ of a fifth force with Yukawa coupling arising from a chameleon- or symmetron-screened scalar field—as well as an unscreened fifth force with differential coupling to galactic mass components—by searching for the displacement it predicts between galaxies’ stellar and gas mass centroids. Taking data from the Alfalfa survey of neutral atomic hydrogen (HI), identifying galaxies’ gravitational environments with the maps of [H. Desmond, P. G. Ferreira, G. Lavaux, and J. Jasche, Mon. Not. R. Astron. Soc. 474, 3152 (2018)] and forward modeling with a Bayesian likelihood framework, we find, with screening included, $6.6\sigma$ evidence for $\mathrm{\Delta }G>0$ at ${\lambda }_C\simeq 2\mathrm{Mpc}$. The maximum-likelihood $\mathrm{\Delta }G/G_N$ is 0.025. A similar fifth force model without screening gives no increase in likelihood over the case $\mathrm{\Delta }G=0$ for any ${\lambda }_C$. Although we validate this result by several methods, we do not claim screened modified gravity to provide the only possible explanation for the data: this conclusion would require knowing that the signal could not be produced by “galaxy formation” physics. We show also the results of a more conservative—though less well-motivated—noise model which yields only upper limits on $\mathrm{\Delta }G/G_N$, ranging from $\sim {10}^{-1}$ for ${\lambda }_C\simeq 0.5\mathrm{Mpc}$ to $\sim \mathrm{few}\times {10}^{-4}$ at ${\lambda }_C\simeq 50\mathrm{Mpc}$. Corresponding models without screening receive the somewhat stronger bounds $\sim \mathrm{few}\times {10}^{-3}$ and $\sim \mathrm{few}\times {10}^{-4}$ respectively. We show how these constraints may be improved by future galaxy surveys and identify the key features of an observational program for directly constraining fifth forces on scales beyond the Solar System. This paper provides a complete description of the analysis summarized in [H. Desmond, P. G. Ferreira, G. Lavaux, and J. Jasche, arXiv:1802.07206].

In a very interesting paper, Andréasson has recently proved that the gravitational mass of a spherically symmetric compact object of radius $R$ and electric charge $Q$ is bounded from above by the relation $\sqrt{M}\le \frac{\sqrt{R}}{3}+\sqrt{\frac{R}{9}+\frac{Q^2}{3R}}$. In the present paper we prove that, in the dimensionless regime $Q/M<\sqrt{9/8}$, a stronger upper bound can be derived on the masses of physically realistic (stable) self-gravitating horizonless compact objects: $M<\frac{R}{3}+\frac{2Q^2}{3R}$.

We study the relationship between signatures of high redshift ionization in large-angle CMB polarization power spectra and features in the Planck 2015 data. Using a principal component (PC) ionization basis that is complete to the cosmic variance limit out to $z_{\max }=30$, 40, 50, we find a robust $>95\%$ CL preference for ionization at $z>15$ with no preference for $z>40$. This robustness originates from the $\ell \sim 10$ region of the data which show high power relative to $\ell \le 8$ and result in a poor fit to a steplike model of reionization. Instead, by allowing for high redshift reionization, the PCs provide a better fit by $2\mathrm{\Delta }\ln \mathcal{L}=5–6$. Due to a degeneracy in the ionization redshift response, this improved fit is due to a single aspect of the model: the ability to accommodate $z>10$ component to the ionization as we illustrate with a two-step reionization model. For this and other models that accommodate such a component, its presence is allowed and even favored; for models that do not, their poor fit reflects statistical or systematic fluctuations. These possibilities produce very different and testable predictions at $\ell \sim 15–20$, as well as small but detectable differences at $\ell >30$ that can further restrict the high redshift limit of reionization.

We study the bounce and cyclicity realization in the framework of new gravitational scalar-tensor theories. In these theories, the Lagrangian contains the Ricci scalar and its first and second derivatives, in a specific combination that makes them free of ghosts, and transformed into the Einstein frame, they are proved to be a subclass of biscalar extensions of general relativity. We present analytical expressions for the bounce requirements, and we examine the necessary qualitative behavior of the involved functions that can give rise to a given scale factor. Having in mind these qualitative forms, we reverse the procedure, and we construct suitable simple Lagrangian functions that can give rise to a bounce or cyclic scale factor.

Many cosmological models have only a finite number of parameters of interest, but a very expensive data-generating process and an intractable likelihood function. We address the problem of performing likelihood-free Bayesian inference from such black-box simulation-based models, under the constraint of a very limited simulation budget (typically a few thousand). To do so, we adopt an approach based on the likelihood of an alternative parametric model. Conventional approaches to approximate Bayesian computation such as likelihood-free rejection sampling are impractical for the considered problem, due to the lack of knowledge about how the parameters affect the discrepancy between observed and simulated data. As a response, we make use of a strategy previously developed in the machine learning literature (Bayesian optimization for likelihood-free inference, bolfi), which combines Gaussian process regression of the discrepancy to build a surrogate surface with Bayesian optimization to actively acquire training data. We extend the method by deriving an acquisition function tailored for the purpose of minimizing the expected uncertainty in the approximate posterior density, in the parametric approach. The resulting algorithm is applied to the problems of summarizing Gaussian signals and inferring cosmological parameters from the joint lightcurve analysis supernovae data. We show that the number of required simulations is reduced by several orders of magnitude, and that the proposed acquisition function produces more accurate posterior approximations, as compared to common strategies.

Each of the potential signals from a black hole–neutron star merger should contain an imprint of the neutron star equation of state: gravitational waves via its effect on tidal disruption, the kilonova via its effect on the ejecta, and the gamma-ray burst via its effect on the remnant disk. These effects have been studied by numerical simulations and quantified by semianalytic formulas. However, most of the simulations on which these formulas are based use equations of state without finite temperature and composition-dependent nuclear physics. In this paper, we simulate black hole–neutron star mergers varying both the neutron star mass and the equation of state, using three finite-temperature nuclear models of varying stiffness. Our simulations largely vindicate formulas for ejecta properties but do not find the expected dependence of disk mass on neutron star compaction. We track the early evolution of the accretion disk, largely driven by shocking and fallback inflow, and do find notable equation-of-state effects on the structure of this early-time, neutrino-bright disk.

Recent measurements of cosmic-ray electron and positron spectra at energies from a GeV to 5 TeV, as well as radio, x-ray and a wide range of gamma-ray observations of pulsar-wind nebulae, indicate that pulsars are significant sources of high-energy cosmic-ray electrons and positrons. Here, we calculate the local cosmic-ray $e^{\pm }$ energy spectra from pulsars taking into account models for (a) the distribution of the pulsars spin-down properties, (b) the cosmic-ray source spectra, and (c) the physics of cosmic-ray propagation. We then use the measured cosmic-ray fluxes from AMS-02, CALET and DAMPE to constrain the space of pulsar and cosmic-ray-propagation models and, in particular, local cosmic-ray diffusion and energy losses, the pulsars’ energy-loss time dependence, and the injected $e^{\pm }$ spectra. We find that the lower estimates for the local $e^{\pm }$ energy losses are inconsistent with the data. We also find that pulsar braking indexes of 2.5 or less for sources with ages more than 10 kyr are strongly disfavored. Moreover, the cosmic-ray data are consistent with a wide range of assumptions on the $e^{\pm }$ injection spectral properties and on the distribution of initial spin-down powers. Above a TeV in energy, we find that pulsars can easily explain the observed change in the $e^{+}+e^{-}$ spectral slope. These conclusions are valid as long as pulsars contribute $\gtrsim 10\%$ of the observed cosmic-ray $e^{\pm }$ at energies $\gtrsim 100\mathrm{GeV}$.