The precise measurements of the high masses of the pulsars PSR $\mathrm{J}1614-2230$ ($M_{1614}=1.97\pm 0.04M_{\odot }$) and PSR $\mathrm{J}0348-0432$ ($M_{0348}=2.01\pm 0.04M_{\odot }$) provide an important constraint for the equation of state of cold, dense matter and are suited to give interesting insights regarding the nature and existence of the possible phase transition to deconfined quark matter in the cores of neutron stars. We analyze the stability and composition of compact star sequences for a class of hybrid nuclear–quark-matter equations of state. The quark matter phase is described in the framework of a standard color superconducting 3-flavor Nambu–Jona-Lasinio model, and the hadronic phase is given by the Dirac–Brueckner–Hartree–Fock equation of state for the Bonn-A potential. The phase transition is obtained by a Maxwell construction. Within this model setup, we aim to constrain otherwise not strictly fixed parameters of the Nambu–Jona-Lasinio model, namely, the coupling strengths in the vector meson and diquark interaction channels. We perform this investigation for two different parametrizations characterized by a different scalar coupling constant. The analysis of flow data obtained in heavy-ion collisions resulted in a further constraint that we account for in our discussion. Massive hybrid stars with extended quark matter cores can be obtained in accordance with all of the considered constraints.

We present the results of simulated injections testing the first Bayesian search pipeline capable of investigating the angular structure of a gravitational-wave (GW) background influencing pulsar signals. A stochastic background of GWs from the incoherent superposition of many inspiraling supermassive black hole binaries at nHz frequencies is likely to be the dominant GW signal detectable by pulsar timing arrays (PTAs). Even though one might expect a background composed of a high-redshift cosmological population of sources to be fairly isotropic, deviations from isotropy may be indicative of local GW hotspots or some form of continuous anisotropy in the angular distribution of GW power. A gravitational-wave background (GWB) induces time-of-arrival deviations in pulsar signals which are correlated between separated pulsars. In an isotropic background this cross correlation follows a distinctive relationship, known as the Hellings and Downs curve, that depends only on the angular separation of the pulsars. If the background is anisotropic, the cross correlation is different, but predictable, and also depends on the absolute position of the pulsars. By simulating data sets containing GWBs with various anisotropic configurations, we have explored the prospects for constraining anisotropy using near future data. We find that at moderate to high signal to noise ratio the assumption of isotropy is no longer an appropriate description of the simulated background. Furthermore, we can recover the nature of the injected anisotropy in a Bayesian parameter-estimation search, and propose a prior on the anisotropy search space motivated by the physicality of the implied distribution of sources. The Tempo2 plugins used to generate pulsar time-of-arrival data sets influenced by anisotropic GWBs can be freely downloaded from the tempo2-anisotropy-plugins GitHub repository.

The squeezed limit of the three-point function of cosmological perturbations is a powerful discriminant of different models of the early Universe. We present a conceptually simple and complete framework to relate any primordial bispectrum in this limit to late time observables, such as the cosmic microwave background (CMB) temperature bispectrum and the scale-dependent halo bias. We employ a series of convenient coordinate transformations to capture the leading nonlinear effects of cosmological perturbation theory on these observables. This makes crucial use of Fermi normal coordinates and their conformal generalization, which we introduce here and discuss in detail. As an example, we apply our formalism to standard slow-roll single-field inflation. We show explicitly that Maldacena’s results for the squeezed limits of the scalar bispectrum [proportional to ($n_s-1$) in comoving gauge] and the tensor-scalar-scalar bispectrum lead to no deviations from a Gaussian universe, except for projection effects. In particular, the primordial contributions to the squeezed CMB bispectrum and scale dependent halo bias vanish, and there are no primordial “fossil” correlations between long-wavelength tensor perturbations and small-scale perturbations. The contributions to observed correlations are then only due to projection effects such as gravitational lensing and redshift perturbations.

Peculiar motions are commonplace in the Universe. Our local group of galaxies, for example, drifts relative to the Hubble flow at about $600\mathrm{km}/\sec $. Such bulk flows are believed to fade away as we move on to progressively larger scales. Recently, however, there have been reports of peculiar motions larger and faster than typically expected. If these claims are correct, the role of peculiar flows in shaping the kinematics of our Universe has probably been underestimated. Here, we use general-relativistic techniques to analyze the average kinematics of large-scale bulk motions and compute the nonlinear Raychaudhuri equation of such flows. In doing so, we introduce two families of observers: one at rest with the Hubble expansion and another following the peculiar motion. We first derive the fully nonlinear expressions of the “peculiar” Raychaudhuri equation in both frames and identify a range of relative motion effects. Linearized around a Friedmann universe with pressureless dust, the full equations reduce to a simple relation with no explicit contribution from the matter component of the universe. Using cosmological perturbation theory, we obtain a scale-dependent formula, which also incorporates the effects of the universe’s inhomogeneity and anisotropy. When the latter are secondary, the peculiar Raychaudhuri equation solves analytically. Also, combining the resulting expression with data from recent peculiar-velocity surveys, we estimate the relative deceleration/acceleration of such bulk motions.

We present a simplified version of the lowest-order embedded point mass gravitational lens theory and then make the extension of this theory to any embedded transparent lens. Embedding a lens effectively reduces the gravitational potential’s range, i.e., partially shields the lensing potential because the lens mass is made a contributor to the mean mass density of the Universe and not simply superimposed upon it. We give the time-delay function for the embedded point mass lens from which we can derive the simplified lens equation by applying Fermat’s least-time principle. Even though rigorous derivations are only made for the point mass in a flat background, the generalization of the lens equation to lowest order for any distributed lens in any homogeneous background is obvious. We find from this simplified theory that embedding can introduce corrections above the few percent level in weak lensing shears caused by large clusters but only at large impacts. The potential part of the time delay is also affected in strong lensing at the few percent level. Additionally we again confirm that the presence of a cosmological constant alters the gravitational deflection of passing photons.

Measuring the anisotropy of the arrival direction distribution of cosmic rays provides important information on the propagation mechanisms and the identification of their sources. In fact, the flux of cosmic rays is thought to be dependent on the arrival direction only due to the presence of nearby cosmic ray sources or particular magnetic-field structures. Recently, the observation of unexpected excesses at TeV energy down to an angular scale as narrow as $\sim 10°$ raised the possibility that the problem of the origin of Galactic cosmic rays may be addressed by studying the anisotropy. The ARGO-YBJ experiment is a full-coverage extensive air showers array, sensitive to cosmic rays with the energy threshold of a few hundred GeV. Searching for small-size deviations from the isotropy, the ARGO-YBJ Collaboration explored the declination region $\delta \sim -20°–80°$, making use of about $3.7\times {10}^{11}$ events collected from November 2007 to May 2012. In this paper, the detection of different significant (up to 13 standard deviations) medium-scale anisotropy regions in the arrival directions of cosmic rays is reported. The observation was performed with unprecedented detail. The relative excess intensity with respect to the isotropic flux extends up to ${10}^{-3}$. The maximum excess occurs for proton energies of 10–20 TeV, suggesting the presence of unknown features of the magnetic fields the charged cosmic rays propagate through, or some contribution of nearby sources never considered so far. The observation of new weaker few-degree excesses throughout the sky region $195°\le \mathrm{R}.\mathrm{A}.\le 290°$ is reported for the first time.

The Higgs boson production associated with a $W$ boson and a photon at the Large Hadron Collider (LHC) can be used to probe the coupling between the Higgs boson and vector gauge bosons and discover a signature of new physics. We present precision predictions up to the QCD next-to-leading order (NLO) in the standard model for this process involving the subsequential weak decays of the final Higgs and $W$ boson. The dependence of the leading order (LO) and the QCD NLO corrected integrated cross sections on the factorization and renormalization energy scale is studied. We provide the LO and QCD NLO corrected distributions of the transverse momenta and rapidities of final products. We find that the LO cross section is significantly enhanced by the QCD NLO correction, and the $K$-factor value is obviously related to the physical observables and the phase space regions.

We use QCD sum rules to study the possible existence of a ${\Theta }_c(3250)$ charmed pentaquark. We consider the contributions of condensates up to dimension 12 and work at leading order in ${\alpha }_s$. We obtain $m_{{\Theta }_c}=(3.29\pm 0.13)\mathrm{GeV}$, compatible with the mass of the structure seen by BABAR Collaboration in the decay channel $B^{-}\to \overline{p}{\Sigma }_c^{++}{\pi }^{-}{\pi }^{-}$. The proposed state is compatible with a previous proposed pentaquark state in the anticharmed sector.

We investigate the impact of direct LHC supersymmetry searches on the parameter space of three natural scenarios in the MSSM. In the first case the spectrum consists of light top squarks, sbottoms, and Higgsino-like neutralinos, while the other particles are assumed to be out of experimental reach. In the second case we consider an additional light gluino. Finally we study a more complex spectrum comprising also light sleptons, a winolike chargino, and a binolike neutralino. We simulate in detail three LHC searches: top squark production at ATLAS with $20.7/\mathrm{fb}$, CMS $11.7/\mathrm{fb}$ inclusive search for squarks and gluinos with the variable ${\alpha }_T$, and CMS $9.2/\mathrm{fb}$ electroweak production with three leptons in the final state. For each point in our scans we calculate the exclusion likelihood due to the individual searches and to their statistical combination. We calculate the fine-tuning measure of the points allowed by the LHC and the implications for the Higgs mass and other phenomenological observables: Higgs signal rates, the relic density, $\mathrm{BR}({\mathrm{B}}_{\mathrm{s}}\to {\mu }^{+}{\mu }^{-})$, $\mathrm{BR}(\overline{\mathrm{B}}\to {\mathrm{X}}_{\mathrm{s}}\gamma )$, and the spin-independent neutralino-proton scattering cross section. We find that points with acceptable levels of fine-tuning are for the most part already excluded by the LHC and including the other constraints further reduces the overall naturalness of our scenarios.

We reconsider prompt photon photoproduction at HERA in the framework of the $k_T$-factorization QCD approach. The proposed method is based on the $\mathcal{O}({\alpha }^2{\alpha }_s)$ amplitudes for $\gamma q\to \gamma gq$ and $\gamma g^{*}\to \gamma q\overline{q}$ partonic subprocesses. Additionally, we take into account the $\mathcal{O}({\alpha }^2{\alpha }_s^2)$ box contributions $\gamma g\to \gamma g$ to the production cross sections. The unintegrated (or transverse momentum dependent) parton densities in the proton are determined using the Kimber-Martin-Ryskin prescription. Our consideration covers both inclusive and jet associated prompt photon photoproduction rates. We find that our numerical predictions agree well with the recent data taken by H1 and ZEUS Collaborations at HERA. We demonstrate that the box contributions are sizable and amount to up to $\sim 15\%$ of the calculated total cross section.

The shape and evolution of the energy spectra of the thunderstorm ground enhancement (TGE) electrons and gamma rays shed light on the origin of TGEs, on the relationship of modification of the energy spectra (MOS) and relativistic runaway electron avalanche processes, on the nature of the seed particles, and on the strength and elongation of an atmospheric electric field. However, till now the measurements of energy spectra of TGE electrons and gamma rays have been rather scarce. For the first time, we present differential energy spectra of gamma rays in the wide energy range 4–100 MeV for five TGE events detected in 2012–2013 at Aragats. We use the special technique of electron/gamma ray fraction determination to select TGE events with very small contamination of electrons. The network of large NaI spectrometers located 3200 m above sea level measured energy spectra of gamma rays. The power law indices of “small” TGEs are rather close to the background cosmic gamma ray spectrum ($\gamma \sim -2$); thus, we may deduce that these small events are due to MOS of cosmic ray electrons in the electric field of a thundercloud. Larger TGEs measured by the NaI network and the two largest TGE events earlier recovered from energy releases in a 60-cm-thick scintillator have much steeper energy spectra typical for the avalanche process in atmosphere. The classification of TGEs according to intensity and gamma ray spectral index pointed toward two main mechanisms of the TGE gamma ray origin: the runaway process and modification of electron energy spectra in the thunderstorm atmospheres.

A search is presented for microscopic black holes in a like-sign dimuon final state in proton–proton collisions at $\sqrt{s}=8\mathrm{TeV}$. The data were collected with the ATLAS detector at the Large Hadron Collider in 2012 and correspond to an integrated luminosity of $20.3{\mathrm{fb}}^{-1}$. Using a high track multiplicity requirement, $0.6\pm 0.2$ background events from Standard Model processes are predicted and none observed. This result is interpreted in the context of low-scale gravity models and 95% C.L. lower limits on microscopic black hole masses are set for different model assumptions.

Using data from proton-antiproton collisions at $\sqrt{s}=1.96\mathrm{TeV}$ recorded by the CDF II detector at the Fermilab Tevatron, evidence for the excited resonance state ${\Lambda }_b^{*0}$ is presented in its ${\Lambda }_b^0{\pi }^{-}{\pi }^{+}$ decay followed by the ${\Lambda }_b^0\to {\Lambda }_c^{+}{\pi }^{-}$ and ${\Lambda }_c^{+}\to p{K}^{-}{\pi }^{+}$ decays. The analysis is based on a data sample corresponding to an integrated luminosity of $9.6{\mathrm{fb}}^{-1}$ collected by an online event selection based on charged-particle tracks displaced from the proton-antiproton interaction point. The significance of the observed signal is $3.5\sigma$. The mass of the observed state is found to be $5919.22\pm 0.76\mathrm{MeV}/c^2$ in agreement with similar findings in proton-proton collision experiments.

We study Seiberg-like dualities for three-dimensional $\mathcal{N}=2$ theories with flavors in fundamental and adjoint representations. The recent results of Intriligator and Seiberg provide a derivation of an Aharony duality from a Giveon–Kutasov duality. We extend their result to the case of more general theories involving various masses for fundamental quarks and adjoint fields. By fine-tuning the vacuum expectation value of a scalar field and using various identifications between gauge groups and their singlet duals, we derive several examples of Aharony dualities. For theories with an adjoint field, we discuss the connection between the Aharony dualities proposed by Kim and Park for theories with multiple Coulomb branches and Giveon–Kutasov–Niarchos dualities.

We study black holes carrying higher spin charge in ${\mathrm{AdS}}_3$ within the framework of $\mathrm{SL}(N,\mathbb{R})\times \mathrm{SL}(N,\mathbb{R})$ Chern-Simons theory. Focusing attention on the $N=4$ case, we explicitly analyze the asymptotic symmetry algebra of black hole solutions with a chemical potential for spin-4 charge. We demonstrate that the background describes a renormalization group (RG) flow between an IR fixed point with ${\mathcal{W}}_4$ symmetry and a UV fixed point with $\mathcal{W}$ symmetry associated to a nonprincipal embedding of $\mathfrak{s}\mathfrak{l}(2)$ in $\mathfrak{s}\mathfrak{l}(4)$. Matching Chern-Simons equations with Ward identities of the deformed conformal field theory, we show that the UV stress tensor is twisted by a certain U(1) current, and the flow is triggered by an operator with dimension $4/3$ at the UV fixed point. We find independent confirmation of this picture via a consistent formulation of thermodynamics with respect to this UV fixed point. We further analyze the thermodynamics of multiple branches of black hole solutions for $N=4$, 5 and find that the BTZ branch, dominant at low temperatures, ceases to exist at higher temperatures following a merger with a thermodynamically unstable branch. We also point out an interesting connection between the RG flows and generalized Korteweg-de Vries hierarchies.

The starting point of any general relativistic numerical simulation is a solution of the Hamiltonian and momentum constraints that (ideally) represents an astrophysically realistic scenario. We present a new method to produce initial data sets for binary neutron stars with arbitrary spins and orbital eccentricities. The method only provides approximate solutions to the constraints. However, we show that the corresponding constraint violations subside after a few orbits, becoming comparable to those found in evolutions of standard conformally flat, helically symmetric binary initial data. We evolve in time data sets corresponding to binaries with spins aligned, zero, and antialigned with the orbital angular momentum. These simulations show the orbital “hang-up” effect previously seen in binary black holes. Additionally, they show orbital eccentricities that can be up to 1 order of magnitude smaller than those found in helically symmetric initial sets evolutions.

As a black hole and neutron star approach during inspiral, the field lines of a magnetized neutron star eventually thread the black hole event horizon and a short-lived electromagnetic circuit is established. The black hole acts as a battery that provides power to the circuit, thereby lighting up the pair just before merger. Although originally suggested as an electromagnetic counterpart to gravitational-wave detection, a black hole battery is of more general interest as a novel luminous astrophysical source. To aid in the theoretical understanding, we present analytic solutions for the electromagnetic fields of a magnetic dipole in the presence of an event horizon. In the limit that the neutron star is very close to a Schwarzschild horizon, the Rindler limit, we can solve Maxwell’s equations exactly for a magnetic dipole on an arbitrary worldline. We present these solutions here and investigate a proxy for a small segment of the neutron star orbit around a big black hole. We find that the voltage the black hole battery can provide is in the range $\sim {10}^{16}$ statvolts with a projected luminosity of ${10}^{42}\mathrm{ergs}/\mathrm{s}$ for an $M=10M_{\odot }$ black hole, a neutron star with a B-field of ${10}^{12}\mathrm{G}$, and an orbital velocity $\sim 0.5c$ at a distance of $3M$ from the horizon. Larger black holes provide less power for binary separations at a fixed number of gravitational radii. The black hole/neutron star system therefore has a significant power supply to light up various elements in the circuit possibly powering bursts, jets, beamed radiation, or even a hot spot on the neutron star crust.

Recent Planck data show the anomalies of cosmic microwave background (CMB) fluctuations on large angular scales, which confirms the early observations by WMAP. We continue studying an inflationary model, in which before the slow-roll inflation the universe is in a contracting phase, and fit the model with the Planck data. We show that this model may generate not only the power deficit at low $l$, but also a large hemispherical power asymmetry in the CMB. We also discuss the implication of the result to the eternal inflation scenario.

Gravitational lensing provides a significant source of cosmological information in modern cosmic microwave background parameter analyses. It is measured in both the power spectrum and trispectrum of the temperature fluctuations. These observables are often treated as independent, although as they are both determined from the same map, this is impossible. In this paper, we perform a rigorous analysis of the covariance between lensing power spectrum and trispectrum analyses. We find two dominant contributions coming from (i) correlations between the disconnected noise bias in the trispectrum measurement and sample variance in the temperature power spectrum and (ii) sample variance of the lenses themselves. The former is naturally removed when the dominant $N^{(0)}$ Gaussian bias in the reconstructed deflection spectrum is dealt with via a partially data-dependent correction, as advocated elsewhere for other reasons. The remaining lens-cosmic-variance contribution is easily modeled but can safely be ignored for a Planck-like experiment, justifying treating the two observable spectra as independent. We also test simple likelihood approximations for the deflection power spectrum, finding that a Gaussian with a parameter-independent covariance performs well.

Following Weinberg’s argument that narrow tetraquark mesons are not precluded in large $N_c$ QCD, we explore the flow of $N_c$ factors needed for the consistency of this picture and show that they must arise in a novel way, not simply through the usual combinatoric counting.