We consider the evolution of a cosmic string loop that is captured by a much more massive and much more compact black hole. We show that after several reconnections that produce ejections of smaller loops, the loop that remains bound to the black hole moves on a nearly-periodic non-self-intersecting trajectory, “the orbit.” The orbit evolves due to an energy and angular momentum exchange between the loop and the spinning black hole. We show that such evolution is mathematically equivalent to a certain continuous deformation of an auxiliary closed curve in a 3-dimensional space; for zero black-hole spin this deformation is curve-shortening that has been extensively studied by mathematicians as a prominent example of one-dimensional geometric flows. The evolution features competing effects of loop growth by the superradiant extraction of the black-hole spin energy, and loop decay by the friction of the moving string against the horizon. Self-intersection of an auxiliary curve may be a common occurrence, which corresponds to a capture by the black hole of a new string segment and thus an addition of a new captured loop. Possible asymptotic states of such evolution are explored and are shown to be strong emitters of gravitational waves. Whether reconnections prevent reaching the asymptotic states remains to be explored. Additionally, the orbit’s shape also evolves due to 1. an emission of gravitational waves, and 2. a finite mass of the black hole, which leads to the recoil that secularly changes the orbit and likely leads to self-intersections. We argue that for a significant range of the dimensionless tension $\mu$, string loops are captured by supermassive black holes at the centers of galaxies. This strongly motivates further study of interaction between string loops and black holes, especially the influence of this process on the black hole spindown and on the production of gravitational waves by strings captured in galactic nuclei. We also discuss potential loop captures by primordial black holes.

It is generally taken for granted that our Universe is free of antimatter objects and domains. This certitude has recently been challenged by the possible detection of antihelium nuclei by AMS-02. Should the observation be confirmed, the existence of nearby antistars would make a plausible hypothesis to explain the origin of the antinuclei. In this paper, we use the 10-year Fermi Large Area Telescope (LAT) gamma-ray source catalog to set constraints on the abundance of antistars around the Sun. We identify in the catalog 14 antistar candidates not associated with any objects belonging to established gamma-ray source classes and with a spectrum compatible with baryon-antibaryon annihilation. We use them along with an estimate of the LAT sensitivity to antistars to set upper limits on the local antistar fraction $f_{\overline{*}}$ with respect to normal stars. We provide parametric limits as a function of the closest antistar mass, velocity, and surrounding matter density. We also employ a novel Monte Carlo method to set limits for a few hypotheses about the antistar population. For a population with properties equivalent to those of regular stars concentrated in the Galactic disk, we obtain $f_{\overline{*}}<2.5\times {10}^{-6}$ at 95% confidence level, which is 20 times more constraining than limits previously available. For a primordial population of antistars distributed in the Galactic halo, we obtain new local upper limits which decrease as a function of antistar mass $M$ from $f_{\overline{*}}<0.2$ at 95% confidence level for $M=1M_{\odot }$ to $f_{\overline{*}}<1.6\times {10}^{-4}$ at 95% confidence level for $M=10M_{\odot }$. By combining these limits with existing microlensing constraints for lighter objects in the Magellanic Clouds, we infer that a primordial population of halo antistars must have a density lower than $\mathcal{O}({10}^{-5}{\mathrm{pc}}^{-3})$ to $\mathcal{O}({10}^{-2}{\mathrm{pc}}^{-3})$ depending on their masses. Our limits can constrain models for the origin and propagation of antinuclei in cosmic rays.

This paper considers diffeomorphism invariant theories of gravity coupled to matter, with second order equations of motion. This includes Einstein-Maxwell and Einstein-scalar field theory with (after field redefinitions) the most general parity-symmetric four-derivative effective field theory corrections. A gauge-invariant approach is used to study the characteristics associated to the physical degrees of freedom in an arbitrary background solution. The symmetries of the principal symbol arising from diffeomorphism invariance and the action principle are determined. For gravity coupled to a single scalar field (i.e., a Horndeski theory) it is shown that causality is governed by a characteristic polynomial of degree 6 which factorizes into a product of quadratic and quartic polynomials. The former is defined in terms of an “effective metric” and is associated with a “purely gravitational” polarization, whereas the latter generically involves a mixture of gravitational and scalar field polarizations. The “fastest” degrees of freedom are associated with the quartic polynomial, which defines a surface analogous to the Fresnel surface in crystal optics. In contrast with optics, this surface is generically nonsingular except on certain surfaces in spacetime. It is shown that a Killing horizon is an example of such a surface. It is also shown that a Killing horizon satisfies the zeroth law of black hole mechanics. The characteristic polynomial defines a cone in the cotangent space and a dual cone in the tangent space. The latter is used to define basic notions of causality and to provide a definition of a dynamical black hole in these theories.

In this work, we explore the connection between the critical curves (“shadows”) and the quasinormal mode frequencies (in the eikonal limit) of Kerr black holes. This mapping has been previously established for nonrotating black holes. We show that the shadow seen by an distant observer at a given inclination angle can be mapped to a family of quasinormal modes with $m/(\ell +1/2)$ bounded within a certain range, where $m$ is azimuthal node number and $\ell$ is the angular node number. We discuss the possibility of testing such relation with spaceborne gravitational wave detectors and the next-generation Event Horizon Telescope.

The Muon $g-2$ Experiment at Fermi National Accelerator Laboratory (FNAL) has measured the muon anomalous precession frequency ${\omega }_a^m$ to an uncertainty of 434 parts per billion (ppb), statistical, and 56 ppb, systematic, with data collected in four storage ring configurations during its first physics run in 2018. When combined with a precision measurement of the magnetic field of the experiment’s muon storage ring, the precession frequency measurement determines a muon magnetic anomaly of $a_{\mu }(\mathrm{FNAL})=116\hspace{0.17em}592\hspace{0.17em}040(54)\times {10}^{-11}$ (0.46 ppm). This article describes the multiple techniques employed in the reconstruction, analysis, and fitting of the data to measure the precession frequency. It also presents the averaging of the results from the 11 separate determinations of ${\omega }_a^m$, and the systematic uncertainties on the result.

We analyze the singularities of the two-point function in a conformal field theory at finite temperature. In a free theory, the only singularity is along the boundary light cone. In the holographic limit, a new class of singularities emerges since two boundary points can be connected by a nontrivial null geodesic in the bulk, encircling the photon sphere of the black hole. We show that these new singularities are resolved by tidal effects due to the black hole curvature, by solving the string world sheet theory in the Penrose limit. Singularities in the asymptotically flat black hole geometry are also discussed.

The LHC is exploring electroweak (EW) physics at the scale EW symmetry is broken. As the LHC and new high energy colliders push our understanding of the Standard Model to ever-higher energies, it will be possible to probe not only the breaking of but also the restoration of EW symmetry. We propose to observe EW restoration in double EW boson production via the convergence of the Goldstone boson equivalence theorem. This convergence is most easily measured in the vector boson plus Higgs production, $Vh$, which is dominated by the longitudinal polarizations. We define EW restoration by carefully taking the limit of zero Higgs vacuum expectation value (vev). EW restoration is then measured through the ratio of the $p_T^h$ distributions between $Vh$ production in the Standard Model and Goldstone boson plus Higgs production in the zero vev theory, where $p_T^h$ is the Higgs transverse momentum. As EW symmetry is restored, this ratio converges to one at high energy. We present a method to extract this ratio from collider data. With a full signal and background analysis, we demonstrate that the 14 TeV HL-LHC can confirm that this ratio converges to one to 40% precision while at the 27 TeV HE-LHC the precision will be 6%. We also investigate statistical tests to quantify the convergence at high energies. Our analysis provides a roadmap for how to stress test the Goldstone boson equivalence theorem and our understanding of spontaneously broken symmetries, in addition to confirming the restoration of EW symmetry.

The thermal and kinematic Sunyaev-Zel’dovich effects (tSZ, kSZ) probe the thermodynamic properties of the circumgalactic and intracluster medium (CGM and ICM) of galaxies, groups, and clusters, since they are proportional, respectively, to the integrated electron pressure and momentum along the line of sight. We present constraints on the gas thermodynamics of CMASS (constant stellar mass) galaxies in the Baryon Oscillation Spectroscopic Survey using new measurements of the kSZ and tSZ signals obtained in a companion paper [Schaan et al.]. Combining kSZ and tSZ measurements, we measure within our model the amplitude of energy injection $\epsilon M_{\star }{c}^2$, where $M_{\star }$ is the stellar mass, to be $\epsilon =(40\pm 9)\times {10}^{-6}$, and the amplitude of the nonthermal pressure profile to be ${\alpha }_{\text{Nth}}<0.2(2\sigma )$, indicating that less than 20% of the total pressure within the virial radius is due to a nonthermal component. We estimate the effects of including baryons in the modeling of weak-lensing galaxy cross-correlation measurements using the best-fit density profile from the kSZ measurement. Our estimate reduces the difference between the original theoretical model and the weak-lensing galaxy cross-correlation measurements in [A. Leauthaud et al., Mon. Not. R. Astron. Soc. 467, 3024 (2017)] by half (50% at most), but does not fully reconcile it. Comparing the kSZ and tSZ measurements to cosmological simulations, we find that they underpredict the CGM pressure and to a lesser extent the CGM density at larger radii with probabilities to exceed ranging from 0.00 to 0.03 and 0.12 to 0.14, for tSZ and kSZ, respectively. This suggests that the energy injected via feedback models in the simulations that we compared against does not sufficiently heat the gas at these radii. We do not find significant disagreement at smaller radii. These measurements provide novel tests of current and future simulations. This work demonstrates the power of joint, high signal-to-noise kSZ and tSZ observations, upon which future cross-correlation studies will improve.

The scattering of cosmic microwave background (CMB) photons off the free-electron gas in galaxies and clusters leaves detectable imprints on high resolution CMB maps: the thermal and kinematic Sunyaev-Zel’dovich effects (tSZ and kSZ respectively). We use combined microwave maps from the Atacama Cosmology Telescope DR5 and Planck in combination with the CMASS (mean redshift $⟨z⟩=0.55$ and host halo mass $⟨M_{\mathrm{vir}}⟩=3\times {10}^{13}{M}_{\odot }$) and LOWZ ($⟨z⟩=0.31$, $⟨M_{\mathrm{vir}}⟩=5\times {10}^{13}{M}_{\odot }$) galaxy catalogs from the Baryon Oscillation Spectroscopic Survey (BOSS DR10 and DR12), to study the gas associated with these galaxy groups. Using individual reconstructed velocities, we perform a stacking analysis and reject the no-kSZ hypothesis at $6.5\sigma$, the highest significance to date. This directly translates into a measurement of the electron number density profile, and thus of the gas density profile. Despite the limited signal to noise, the measurement shows at high significance that the gas density profile is more extended than the dark matter density profile, for any reasonable baryon abundance (formally $>90\sigma$ for the cosmic baryon abundance). We simultaneously measure the tSZ signal, i.e., the electron thermal pressure profile of the same CMASS objects, and reject the no-tSZ hypothesis at $10\sigma$. We combine tSZ and kSZ measurements to estimate the electron temperature to 20% precision in several aperture bins, and find it comparable to the virial temperature. In a companion paper, we analyze these measurements to constrain the gas thermodynamics and the properties of feedback inside galaxy groups. We present the corresponding LOWZ measurements in this paper, ruling out a null kSZ (tSZ) signal at 2.9 $(13.9)\sigma$, and leave their interpretation to future work. This paper and the companion paper demonstrate that current CMB experiments can detect and resolve gas profiles in low mass halos and at high redshifts, which are the most sensitive to feedback in galaxy formation and the most difficult to measure any other way. They will be a crucial input to cosmological hydrodynamical simulations, thus improving our understanding of galaxy formation. These precise gas profiles are already sufficient to reduce the main limiting theoretical systematic in galaxy-galaxy lensing: baryonic uncertainties. Future such measurements will thus unleash the statistical power of weak lensing from the Rubin, Euclid and Roman observatories. Our stacking software ThumbStackis publicly available and directly applicable to future Simons Observatory and CMB-S4 data.

We point out that there can be humanly traversable wormhole solutions in some previously considered theories for physics beyond the Standard Model, namely the Randall-Sundrum model.

New measurements of the expansion rate of the Universe have plunged the standard model of cosmology into a severe crisis. In this paper, we propose a simple resolution to the problem that relies on a first order phase transition in a dark sector in the early Universe, before recombination. This will lead to a short phase of a new early dark energy (NEDE) component and can explain the observations. We model the false vacuum decay of the NEDE scalar field as a sudden transition from a cosmological constant source to a decaying fluid with constant equation of state. The corresponding fluid perturbations are covariantly matched to the adiabatic fluctuations of a subdominant scalar field that triggers the phase transition. Fitting our model to measurements of the cosmic microwave background (CMB), baryonic acoustic oscillations (BAO, and supernovae (SNe) yields a significant improvement of the best fit compared with the standard cosmological model without NEDE. We find the mean value of the present Hubble parameter in the NEDE model to be $H_0=71.4\pm 1.0\mathrm{km}{\mathrm{s}}^{-1}{\mathrm{Mpc}}^{-1}$ (68% C.L.).

Some recently proposed definitions of Jackiw-Teitelboim (JT) gravity and supergravities in terms of combinations of minimal string models are explored, with a focus on physics beyond the perturbative expansion in spacetime topology. While this formally involves solving infinite-order nonlinear differential equations, it is shown that the physics can be extracted to arbitrarily high accuracy in a simple controlled truncation scheme, using a combination of analytical and numerical methods. The nonperturbative spectral densities are explicitly computed and exhibited. The full spectral form factors, involving crucial nonperturbative contributions from wormhole geometries, are also computed and displayed, showing the nonperturbative details of the characteristic “slope,” “dip,” “ramp,” and “plateau” features. It is emphasized that results of this kind can most likely be readily extracted for other types of JT gravity using the same methods.

It is proposed that a family of Jackiw-Teitelboim supergravites, recently discussed in connection with matrix models by Stanford and Witten, can be given a complete definition, to all orders in the topological expansion and beyond, in terms of a specific combination of minimal string theories. This construction defines nonperturbative physics for the supergravity that is well defined and stable. The minimal models come from double-scaled complex matrix models and correspond to the cases $(2\mathrm{\Gamma }+1,2)$ in the Altland-Zirnbauer $(\mathit{\alpha },\mathit{\beta })$ classification of random matrix ensembles, where $\mathrm{\Gamma }$ is a parameter. A central role is played by a nonlinear “string equation” that naturally incorporates $\mathrm{\Gamma }$, usually taken to be an integer, counting, e.g., D-branes in the minimal models. Here, half-integer $\mathrm{\Gamma }$ also has an interpretation. In fact, $\mathrm{\Gamma }=\pm \frac{1}{2}$ yields the cases (0,2) and (2,2) that were shown by Stanford and Witten to have very special properties. These features are manifest in this definition because the relevant solutions of the string equation have special properties for $\mathrm{\Gamma }=\pm \frac{1}{2}$. Additional special features for other half-integer $\mathrm{\Gamma }$’s suggest new surprises in the supergravity models.

We present stationary solutions of magnetized, viscous thick accretion disks around a Schwarzschild black hole. We assume that the tori are not self-gravitating, are endowed with a toroidal magnetic field and obey a constant angular momentum law. Our study focuses on the role of the black hole curvature in the shear viscosity tensor and in their potential combined effect on the stationary solutions. Those are built in the framework of a causality-preserving, second-order gradient expansion scheme of relativistic hydrodynamics in the Eckart frame description which gives rise to hyperbolic equations of motion. The stationary models are constructed by numerically solving the general relativistic momentum conservation equation using the method of characteristics. We place constraints in the range of validity of the second-order transport coefficients of the theory. Our results reveal that the effects of the shear viscosity and curvature are particularly noticeable only close to the cusp of the disks. The surfaces of constant pressure are affected by viscosity and curvature and the self-intersecting iscocontour—the cusp—moves to smaller radii (i.e., toward the black hole horizon) as the effects become more significant. For highly magnetized disks the shift in the cusp location is smaller. Our findings might have implications for the dynamical stability of constant angular momentum tori which, in the inviscid case, are affected by the runaway instability.

We study quantum noise and decoherence induced by gravitons. We derive a Langevin equation of geodesic deviation in the presence of gravitons. The amplitude of noise correlations tells us that large squeezing is necessary to detect the noise. We also consider the decoherence of spatial superpositions of two massive particles caused by gravitons in the vacuum state and find that gravitons could give a relevant contribution to the decoherence. The decoherence induced by gravitons would offer new vistas to test quantum gravity in tabletop experiments.

We present a detailed report on sterile neutrino oscillation and ${}^{235}\mathrm{U}$ ${\overline{\nu }}_e$ energy spectrum measurement results from the PROSPECT experiment at the highly enriched High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. In 96 calendar days of data taken at an average baseline distance of 7.9 m from the center of the 85 MW HFIR core, the PROSPECT detector has observed more than 50,000 interactions of ${\overline{\nu }}_e$ produced in beta decays of ${}^{235}\mathrm{U}$ fission products. New limits on the oscillation of ${\overline{\nu }}_e$ to light sterile neutrinos have been set by comparing the detected energy spectra of ten reactor-detector baselines between 6.7 and 9.2 meters. Measured differences in energy spectra between baselines show no statistically significant indication of ${\overline{\nu }}_e$ to sterile neutrino oscillation and disfavor the reactor antineutrino anomaly best-fit point at the $2.5\sigma$ confidence level. The reported ${}^{235}\mathrm{U}$ ${\overline{\nu }}_e$ energy spectrum measurement shows excellent agreement with energy spectrum models generated via conversion of the measured ${}^{235}\mathrm{U}$ beta spectrum, with a ${\chi }^2/\mathrm{d}.\mathrm{o}.\mathrm{f}.$ of $31/31$. PROSPECT is able to disfavor at $2.4\sigma$ confidence level the hypothesis that ${}^{235}\mathrm{U}$ ${\overline{\nu }}_e$ are solely responsible for spectrum discrepancies between model and data obtained at commercial reactor cores. A data-model deviation in PROSPECT similar to that observed by commercial core experiments is preferred with respect to no observed deviation, at a $2.2\sigma$ confidence level.

One of the most interesting candidates for dark matter is massive real scalar particles. A well-motivated example is from a pure Yang-Mills hidden sector, which locks up into glueballs in the early universe. The lightest glueball states are scalar particles and can act as a form of bosonic dark matter. If self-interactions are repulsive, this can potentially lead to very massive boson stars, where the inward gravitational force is balanced by the repulsive self-interaction. This can also arise from elementary real scalars with a regular potential. In the literature it has been claimed that this allows for astrophysically significant boson stars with high compactness, which could undergo binary mergers and generate detectable gravitational waves. Here we show that previous analyses did not take into proper account $3\to 2$ and $4\to 2$ quantum mechanical annihilation processes in the core of the star, while other work misinterpreted the classical $3\to 1$ process. In this work, we compute the annihilation rates, finding that massive stars will rapidly decay from the $3\to 2$ or $4\to 2$ processes (while the $3\to 1$ process is typically small). Using the Einstein-Klein-Gordon equations, we also estimate the binding energy of these stars, showing that even the densest stars do not have quite enough binding energy to prevent annihilations. For such boson stars to live for the current age of the universe and to be consistent with bounds on dark matter scattering in galaxies, we find the following upper bound on their mass for $\mathcal{O}(1)$ self-interaction couplings: $M_{*}\lesssim {10}^{-18}{M}_{\mathrm{sun}}$ when $3\to 2$ processes are allowed and $M_{*}\lesssim {10}^{-11}{M}_{\mathrm{sun}}$ when only $4\to 2$ processes are allowed. We also estimate destabilization from parametric resonance which can considerably constrain the phase space further. Furthermore, such stars are required to have very small compactness to be long-lived.

In a vacuum first-order phase transition, gravitational waves are generated from collision of bubbles of the true vacuum. The spectrum from such collisions takes the form of a broken power law. We consider a toy model for such a phase transition, where the dynamics of the scalar field depends on a single parameter $\overline{\lambda }$, which controls how thin the bubble wall is at nucleation and how close to degenerate the vacua are relative to the barrier. We extend on our previous work by performing a series of simulations with a range of $\overline{\lambda }$. The peak of the gravitational-wave power spectrum varies by up to a factor of 1.3, which is probably an unobservable effect. We find that the UV power law in the gravitational-wave spectrum becomes steeper as $\overline{\lambda }\to 0$, varying between $k^{-1.4}$ and $k^{-2.2}$ for the $\overline{\lambda }$ considered. This provides some evidence that the form of the underlying effective potential of a vacuum first-order phase transition could be determined from the gravitational-wave spectrum it produces.

The importance of detecting neutrinos from a Milky Way core-collapse supernova is well known. An understudied phase is proto-neutron star cooling. For SN 1987A, this seemingly began at about 2 s and is thus probed by only 6 of the 19 events (and only the ${\overline{\nu }}_e$ flavor) in the Kamiokande-II and IMB detectors. With the higher statistics expected for present and near-future detectors, it should be possible to measure detailed neutrino signals out to very late times. We present the first comprehensive study of neutrino detection during the proto-neutron star cooling phase, considering a variety of outcomes, using all flavors, and employing detailed detector physics. For our nominal model, the event yields (at 10 kpc) after 10 s—the approximate duration of the SN 1987A signal—far exceed the entire SN 1987A yield, with $\simeq 250$ ${\overline{\nu }}_e$ events (to 50 s) in Super-Kamiokande, $\simeq 110$ ${\nu }_e$ events (40 s) in the Deep Underground Neutrino Experiment (DUNE), and $\simeq 10$ ${\nu }_{\mu },{\nu }_{\tau },{\overline{\nu }}_{\mu },{\overline{\nu }}_{\tau }$ events (to 20 s) in the Jiangmen Underground Neutrino Observatory. These data would allow unprecedented probes of the proto-neutron star, including the onset of neutrino transparency and hence its transition to a neutron star. If a black hole forms, even at very late times, this can be clearly identified. But will the detectors fulfill their potential for this perhaps once-ever opportunity for an all-flavor, high-statistics detection of a core collapse? Maybe. Further work is urgently needed, especially for DUNE to thoroughly investigate and improve its MeV capabilities.

QCD instantons are arguably the best motivated yet unobserved nonperturbative effects predicted by the Standard Model. A discovery and detailed study of instanton-generated processes at colliders would provide a new window into the phenomenological exploration of QCD and a vastly improved fundamental understanding of its nonperturbative dynamics. Building on the optical theorem, we numerically calculate the total instanton cross section from the elastic scattering amplitude, also including quantum effects arising from resummed perturbative exchanges between hard gluons in the initial state, thereby improving in accuracy on previous results. Although QCD instanton processes are predicted to be produced with a large scattering cross section at small center-of-mass partonic energies, discovering them at hadron colliders is a challenging task that requires dedicated search strategies. We evaluate the sensitivity of high-luminosity LHC runs, as well as low-luminosity LHC and Tevatron runs. We find that LHC low-luminosity runs in particular, which do not suffer from large pileup and trigger thresholds, show a very good sensitivity for discovering QCD instanton-generated processes.