We consider Einstein gravity minimally coupled to a scalar field with a given potential in general dimensions. We obtain large classes of static hairy planar black holes which are asymptotic to anti-de Sitter (AdS) space-times. In particular, for a special case $\mu =(n-2)/2$, we obtain new classes of exact dynamical solutions describing black hole formation. We find there are two classes of collapse solutions. The first class of solutions describes the evolution start from AdS space-time with a naked singularity at the origin. The space-time is linearly unstable and evolves into stationary black hole states even under small perturbation. The second class of solutions describes the space-time spontaneously evolving from AdS vacua into stationary black hole states undergoing nonlinear instability. We also discuss the global properties of all these dynamical solutions.

We consider gamma-ray burst (GRB) jets that are choked by extended material as sources of high-energy cosmic neutrinos. We take into account the jet propagation physics both inside the progenitor star and the surrounding dense medium. Radiation constraints, which are relevant for high-energy neutrino production, are considered as well. Efficient shock acceleration of cosmic rays is possible for sufficiently low-power jets and/or jets buried in a dense, extended wind or outer envelope. Such conditions also favor GRB jets to become stalled, and the necessary conditions for stalling are explicitly derived. Such choked jets may explain transrelativistic supernovae (SNe) and low-luminosity (LL) GRBs, giving a unified picture of GRBs and GRB-SNe. Focusing on this unified scenario for GRBs, we calculate the resulting neutrino spectra from choked jets, including the relevant microphysical processes such as multipion production in $pp$ and $p\gamma$ interactions, as well as the energy losses of mesons and muons. We obtain diffuse neutrino spectra using the latest results for the luminosity function of LL GRBs. Although uncertainties are large, we confirm that LL GRBs can potentially give a significant contribution to the diffuse neutrino flux. Our results are consistent with the present IceCube data and do not violate the stacking limits on classical high-luminosity GRBs. We find that high-energy neutrino production in choked jets is dominated by $p\gamma$ interactions. These sources are dark in GeV-TeV gamma rays and do not contribute significantly to the Fermi diffuse gamma-ray background. Assuming stalled jets can launch a quasispherical shock in the dense medium, “precursor” TeV neutrinos emerging prior to the shock breakout gamma-ray emission can be used as smoking-gun evidence for a choked jet model for LL GRBs. Our results strengthen the relevance of wide field-of-view sky monitors with better sensitivities in the 1–100 keV range.

We have measured the gamma-ray emission spectrum of the Moon using the data collected by the Large Area Telescope onboard the Fermi satellite during its first seven years of operation, in the energy range from 30 MeV up to a few GeV. We have also studied the time evolution of the flux, finding a correlation with the solar activity. We have developed a full Monte Carlo simulation describing the interactions of cosmic rays with the lunar surface. The results of the present analysis can be explained in the framework of this model, where the production of gamma rays is due to the interactions of cosmic-ray proton and helium nuclei with the surface of the Moon. Finally, we have used our simulation to derive the cosmic-ray proton and helium spectra near Earth from the Moon gamma-ray data.

Liquid argon is a bright scintillator with potent particle identification properties, making it an attractive target for direct-detection dark matter searches. The DarkSide-50 dark matter search here reports the first WIMP search results obtained using a target of low-radioactivity argon. DarkSide-50 is a dark matter detector, using a two-phase liquid argon time projection chamber, located at the Laboratori Nazionali del Gran Sasso. The underground argon is shown to contain ${}^{39}\mathrm{Ar}$ at a level reduced by a factor $(1.4\pm 0.2)\times {10}^3$ relative to atmospheric argon. We report a background-free null result from $(2616\pm 43)\mathrm{kg}\mathrm{d}$ of data, accumulated over 70.9 live days. When combined with our previous search using an atmospheric argon, the 90% C.L. upper limit on the WIMP-nucleon spin-independent cross section, based on zero events found in the WIMP search regions, is $2.0\times {10}^{-44}{\mathrm{cm}}^2$ ($8.6\times {10}^{-44}{\mathrm{cm}}^2$, $8.0\times {10}^{-43}{\mathrm{cm}}^2$) for a WIMP mass of $100\mathrm{GeV}/c^2$ ($1\mathrm{TeV}/c^2$, $10\mathrm{TeV}/c^2$).

We discuss the determination of the $f_0(500)$ (or $\sigma$) resonance by analytic continuation through Padé approximants of the $\pi \pi$-scattering amplitude from the physical region to the pole in the complex energy plane. The aim is to analyze the uncertainties of the method, having in view the fact that analytic continuation is an ill-posed problem in the sense of Hadamard. Using as input a class of admissible parametrizations of the scalar-isoscalar $\pi \pi$ partial wave, which satisfy with great accuracy the same set of dispersive constraints, we find that the Roy-type integral representations lead to almost identical pole positions for all of them, while the predictions of the Padé approximants have a larger spread, being sensitive to features of the input parametrization that are not controlled by the dispersive constraints. Our conservative conclusion is that the $\sigma$-pole determination by Padé approximants is consistent with the prediction of Roy-type equations, but has an uncertainty almost a factor of 2 larger.

Spin-one matter fields are relevant both for the description of hadronic states and as potential extensions of the Standard Model. In this work we present a formalism for the description of massive spin-one fields transforming in the $(1,0)\oplus (0,1)$ representation of the Lorentz group, based on the covariant projection onto parity eigenspaces and Poincaré orbits. The formalism yields a constrained dynamics. We solve the constraints and perform the canonical quantization accordingly. This formulation uses the recent construction of a parity-based covariant basis for matrix operators acting on the $(j,0)\oplus (0,j)$ representations. The algebraic properties of the covariant basis play an important role in solving the constraints and allowing the canonical quantization of the theory. We study the chiral structure of the theory and conclude that it is not chirally symmetric in the massless limit, hence it is not possible to have chiral gauge interactions. However, spin-one matter fields can have vector gauge interactions. Also, the dimension of the field makes self-interactions naively renormalizable. Using the covariant basis, we classify all possible self-interaction terms.

By exploiting the relatively long lifetime of the tau lepton, we propose several novel methods for searching for new physics at an electron-positron collider. We consider processes that involve final states consisting of a tau lepton pair plus two missing particles. The mass and spin of the new physics particles can be measured in 3-prong tau decays. The tau polarization, which reflects the coupling to new physics, can be measured from the $\tau \to \pi \nu$ decay channel using the impact parameter distribution of the charged pion. We also discuss the corresponding backgrounds for these measurements, the next-to-leading order (NLO) effects, and the implications of finite detector resolution.

Distinguishing a dark matter interaction from an astrophysical neutrino-induced interaction will be major challenge for future direct dark matter searches. In this paper, we consider this issue within nonrelativistic effective field theory (EFT), which provides a well-motivated theoretical framework for determining nuclear responses to dark matter scattering events. We analyze the nuclear energy recoil spectra from the different dark matter-nucleon EFT operators, and compare them to the nuclear recoil energy spectra that are predicted to be induced by astrophysical neutrino sources. We determine that for 11 of the 14 possible operators, the dark matter-induced recoil spectra can be cleanly distinguished from the corresponding neutrino-induced recoil spectra with moderate-size detector technologies that are now being pursued, e.g., these operators would require 0.5 tonne years to be distinguished from the neutrino background for low mass dark matter. Our results imply that in most models detectors with good energy resolution will be able to distinguish a dark matter signal from a neutrino signal, without the need for much larger detectors that must rely on additional information from timing or direction. In addition we calculate up-to-date exclusion limits in the EFT model space using data from the LUX experiment.

We extend earlier investigations of heavy-light pseudoscalar mesons to the vector case, using a simple model in the context of the Dyson-Schwinger-Bethe-Salpeter approach. We investigate the effects of a dressed quark-gluon vertex in a systematic fashion and illustrate and attempt to quantify corrections beyond the phenomenologically very useful and successful rainbow-ladder truncation. In particular we investigate the dressed quark-photon vertex in such a setup and make a prediction for the experimentally as yet unknown mass of the $B_c^{*}$, which we obtain at 6.334 GeV well in line with predictions from other approaches. Furthermore, we combine a comprehensive set of results from the theoretical literature. The theoretical average for the mass of the $B_c^{*}$ meson is $6.336\pm 0.002\mathrm{GeV}$.

We study the transverse single-spin asymmetry with a $\sin {\varphi }_S$ modulation in semi-inclusive deep inelastic scattering. In particular, we consider the case in which the transverse momentum of the final state hadron is integrated out. Thus, the asymmetry is merely contributed by the coupling of the transversity distribution function $h_1(x)$ and the twist-3 collinear fragmentation function $\tilde{H}(z)$. Using the available parametrization of $h_1(x)$ from SIDIS data and the recent extracted result for $\tilde{H}(z)$, we predict the $\sin {\varphi }_S$ asymmetry for charged and neutral pion production at an electron ion collider. We find that the asymmetry is sizable and could be measured. We also study the impact of the leading-order QCD evolution effect and find that it affects the $\sin {\varphi }_S$ asymmetry at an electron ion collider considerably.

We construct a neutrino model of three twin neutrinos in light of the neutrino appearance excesses at LSND and MiniBooNE. The model, which includes a twin parity, naturally predicts identical lepton Yukawa structures in the Standard Model and the twin sectors. As a result, a universal mixing angle controls all three twin neutrino couplings to the Standard Model charged leptons. This mixing angle is predicted to be the ratio of the electroweak scale over the composite scale of the Higgs boson and has the right order of magnitude to fit the data. The heavy twin neutrinos decay within the experimental lengths into active neutrinos plus a long-lived Majoron and can provide a good fit, at around the $4\sigma$ confidence level, to the LSND and MiniBooNE appearance data while simultaneously satisfying the disappearance constraints. For the Majorana neutrino case, the fact that neutrinos have a larger scattering cross section than antineutrinos provides a natural explanation to MiniBooNE’s observation of a larger antineutrino appearance excess.

The long-baseline experiment T2K in Japan has collected data in the neutrino mode corresponding to an exposure of $6.57\times {10}^{20}$ POT (protons on target), and currently it is running in the antineutrino mode. The main aim of the antineutrino run is to measure the leptonic phase ${\delta }_{CP}$, which may help in understanding the matter-antimatter asymmetry of the Universe. In this work, we show that in T2K, antineutrinos are required only for removing the wrong-octant solutions, which in turn improves the $CP$ sensitivity. If, however, the octant is known, then a pure neutrino run is capable of giving the maximum $CP$ sensitivity. If we divide the total true parameter space into eight sets, then we find that the T2K antineutrino run helps in improving the $CP$ sensitivity for only two sets, while for the remaining six combinations the pure neutrino run gives the best $CP$ sensitivity. Thus, if the neutrino run is replaced by the antineutrino run, then it causes a reduction in the $CP$ sensitivity in 75% of the true parameter space due to lesser statistics. Thus, it is worthwhile to study if the T2K antineutrino run can be reduced by the antineutrino runs of the other experiments, so that T2K can run in dominant neutrino mode to extract the best $CP$ sensitivity. In this work, we explore the possibilities of the antineutrino component of $\mathrm{NO}\nu \mathrm{A}$ and the atmospheric neutrino experiment ICAL@INO for compensating the antineutrino run of T2K.

Numerous anomalous results in neutrino oscillation experiments can be attributed to the interference of an $\sim 1\mathrm{eV}$ sterile neutrino. The Baksan Experiment on Sterile Transitions (BEST), specially designed to fully explore the Gallium anomaly, starts next year. We investigate the sensitivity of BEST in search of a sterile neutrino mixed with an electron neutrino. Then, performing the combined analysis of all the Gallium experiments (SAGE, GALLEX, BEST), we find the region in the model parameter space (sterile neutrino mass and mixing angle) which will be excluded if BEST agrees with no sterile neutrino hypothesis. For the opposite case, if BEST observes the signal as it follows from the sterile neutrino explanation of the Gallium (SAGE and GALLEX) anomaly, we show how BEST will improve upon the present estimates of the model parameters.

In this short note, we come back to the recent proposal put forward by Kharzeev and Levin [Phys. Rev. Lett. 114, 242001 (2015)], in which they phenomenologically couple the nonperturbative Veneziano ghost to the perturbative gluon, leading to a modified gluon propagator (the “glost”) of the Gribov type, with complex poles. As such, a possible link was made between the QCD topological $\theta$-vacuum (Veneziano ghost) and color confinement (no physically observable gluons). We discuss some subtleties concerning gauge (Becchi-Rouet-Stora-Tuytin) invariance of this proposal, related to the choice of Feynman gauge. We draw particular attention to the incompatibility in the longitudinal sector with available nonperturbative results for the linear covariant gauge. We furthermore provide an example in the Landau gauge of a similar phenomenological vertex that also describes the necessary Veneziano ghost but does not affect the Landau gauge gluon propagator.

We study the motion of charged particles in the field of a rotating black hole immersed into an external asymptotically uniform magnetic field, focusing on the epicyclic quasicircular orbits near the equatorial plane. Separating the circular orbits into four qualitatively different classes according to the sign of the canonical angular momentum of the motion and the orientation of the Lorentz force, we analyze the circular orbits using the so-called force formalism. We find the analytical solutions for the radial profiles of velocity, specific angular momentum, and specific energy of the circular orbits in dependence on the black-hole dimensionless spin and the magnetic field strength. The innermost stable circular orbits are determined for all four classes of the circular orbits. The stable circular orbits with an outward-oriented Lorentz force can extend to radii lower than the radius of the corresponding photon circular geodesic. We calculate the frequencies of the harmonic oscillatory motion of the charged particles in the radial and vertical directions related to the equatorial circular orbits and study the radial profiles of the radial, ${\omega }_{\mathrm{r}}$; vertical, ${\omega }_{\theta }$; and orbital, ${\omega }_{\varphi }$, frequencies, finding significant differences in comparison to the epicyclic geodesic circular motion. The most important new phenomenon is the existence of toroidal charged particle epicyclic motion with ${\omega }_{\mathrm{r}}\sim {\omega }_{\theta }\gg {\omega }_{\varphi }$ that could occur around retrograde circular orbits with an outward-oriented Lorentz force. We demonstrate that for the rapidly rotating black holes the role of the “Wald induced charge” can be relevant.

We evaluate the Hadamard function and the vacuum expectation value of the current density for a charged scalar field in the region between two codimension-one branes on the background of locally anti–de Sitter (AdS) spacetime with an arbitrary number of toroidally compactified spatial dimensions. Along compact dimensions periodicity conditions are considered with general values of the phases and on the branes Robin boundary conditions are imposed for the field operator. In addition, we assume the presence of a constant gauge field. The latter gives rise to an Aharonov-Bohm-type effect on the vacuum currents. There exists a range in the space of the Robin coefficients for separate branes where the vacuum state becomes unstable. Compared to the case of the standard AdS bulk, in models with compact dimensions the stability condition imposed on the parameters is less restrictive. The current density has nonzero components along compact dimensions only. These components are decomposed into the brane-free and brane-induced contributions. Different representations are provided for the latter that are well suited for the investigation of the near-brane, near-AdS boundary and near-AdS horizon asymptotics. An important feature, that distinguishes the current density from the expectation values of the field squared and energy-momentum tensor, is its finiteness on the branes. In particular, for Dirichlet boundary conditions the current density vanishes on the branes. We show that, depending on the constants in the boundary conditions, the presence of the branes may either increase or decrease the current density compared with that for the brane-free geometry. Applications are given to the Randall-Sundrum 2-brane model with extra compact dimensions. In particular, we estimate the effects of the hidden brane on the current density on the visible brane.

We investigate universal relations between different normalizations of the moment of inertia and the compactness of neutron and strange stars. Slowly rotating as well as rapidly rotating models are studied in general relativity, ${\mathcal{R}}^2$ gravity and scalar-tensor theories of gravity. Moment-of-inertia–compactness relations are examined for different normalizations of the moment of inertia. It is shown that for all studied cases the deviations from equation-of-state universality are small for the examined equations of state. It turns out that in some of the cases the examined relations are also theory independent to a good extent. Universality in relations between the maximum mass and the moment of inertia for some unstable models is also investigated.

Small-field inflation (SFI) is widely considered to be unnatural because an extreme fine-tuning of the initial condition is necessary for sufficiently large $e$-folding. In this paper, we show that the unnaturally looking initial condition can be dynamically realized without any fine-tuning if the SFI occurs after rapid oscillations of the inflaton field and particle creations by preheating. In fact, if the inflaton field $\varphi$ is coupled to another scalar field $\chi$ through the interaction $g^2{\chi }^2{\varphi }^2$ and the vacuum energy during the small field inflation is given by $\lambda M^4$, the initial value can be dynamically set at $(\sqrt{\lambda }/g)M^2/M_{\mathrm{pl}}$, which is much smaller than the typical scale of the potential $M$. This solves the initial condition problem in the new inflation model or some classes of the hilltop inflation models.