The OPERA experiment is designed to search for ${\nu }_{\mu }\to {\nu }_{\tau }$ oscillations in appearance mode, i.e., through the direct observation of the $\tau$ lepton in ${\nu }_{\tau }$-charged current interactions. The experiment has taken data for five years, since 2008, with the CERN Neutrino to Gran Sasso beam. Previously, two ${\nu }_{\tau }$ candidates with a $\tau$ decaying into hadrons were observed in a subsample of data of the 2008–2011 runs. Here we report the observation of a third ${\nu }_{\tau }$ candidate in the ${\tau }^{-}\to {\mu }^{-}$ decay channel coming from the analysis of a subsample of the 2012 run. Taking into account the estimated background, the absence of ${\nu }_{\mu }\to {\nu }_{\tau }$ oscillations is excluded at the $3.4\sigma$ level.

We describe searches for $B$ meson decays to the charmless vector-vector final states $\omega \omega$ and $\omega \varphi$ with $471\times 10^{6}B\overline{B}$ pairs produced in $e^{+}{e}^{-}$ annihilation at $\sqrt{s}=10.58\mathrm{GeV}$ using the BABAR detector at the PEP-II collider at the SLAC National Accelerator Laboratory. We measure the branching fraction $\mathcal{B}(B^0\to \omega \omega )=(1.2\pm {0.3}_{-0.2}^{+0.3})\times {10}^{-6}$, where the first uncertainty is statistical and the second is systematic, corresponding to a significance of 4.4 standard deviations. We also determine the upper limit $\mathcal{B}(B^0\to \omega \varphi )<0.7\times {10}^{-6}$ at 90% confidence level. These measurements provide the first evidence for the decay $B^0\to \omega \omega$, and an improvement of the upper limit for the decay $B^0\to \omega \varphi$.

Light is affected by local inhomogeneities in its propagation, which may alter distances and so cosmological parameter estimation. In the era of precision cosmology, the presence of inhomogeneities may induce systematic errors if not properly accounted. In this vein, a new interpretation of the conventional Dyer-Roeder (DR) approach by allowing light received from distant sources to travel in regions denser than average is proposed. It is argued that the existence of a distribution of small and moderate cosmic voids (or “black regions”) implies that its matter content was redistributed to the homogeneous and clustered matter components with the former becoming denser than the cosmic average in the absence of voids. Phenomenologically, this means that the DR smoothness parameter (denoted here by ${\alpha }_E$) can be greater than unity, and, therefore, all previous analyses constraining it should be rediscussed with a free upper limit. Accordingly, by performing a statistical analysis involving 557 type Ia supernovae (SNe Ia) from Union2 compilation data in a flat $\mathrm{\Lambda }\mathrm{CDM}$ model, we obtain for the extended parameter ${\alpha }_E=1.26_{-0.54}^{+0.68}$ ($1\sigma$). The effects of ${\alpha }_E$ are also analyzed for generic $\mathrm{\Lambda }\mathrm{CDM}$ models and flat XCDM cosmologies. For both models, we find that a value of ${\alpha }_E$ greater than unity is able to harmonize SNe Ia and cosmic microwave background observations thereby alleviating the well-known tension between low and high redshift data. Finally, a simple toy model based on the existence of cosmic voids is proposed in order to justify why ${\alpha }_E$ can be greater than unity as required by supernovae data.

We present two new classes of dyonic anti–de Sitter black hole solutions of four-dimensional maximal $\mathcal{N}=8$, SO(8) gauged supergravity. They are (1) static black holes of $\mathcal{N}=2$, $\mathrm{U}(1{)}^4$ gauged supergravity with four electric and four magnetic charges, with spherical, planar or hyperbolic horizons; and (2) rotating black holes of $\mathcal{N}=2$, $\mathrm{U}(1{)}^2$ gauged supergravity with two electric and two magnetic charges. We study their thermodynamics, and point out that the formulation of a consistent thermodynamics for dyonic anti–de Sitter black holes is dependent on the existence of boundary conditions for the gauge fields. We identify several distinct classes of boundary conditions for gauge fields in $\mathrm{U}(1{)}^4$ supergravity. We study a general family of metrics containing the rotating solutions, and find Killing-Yano tensors with torsion in two conformal frames, which underlie separability.

We discuss the ultraviolet and infrared perturbative finiteness of massless ${\mathrm{QED}}_3$, which is parity and infrared anomaly-free to all orders in perturbation theory.

Massless fields propagating in a generic Kerr black hole background enjoy a hidden $SL(2,\mathbb{R})\times SL(2,\mathbb{R})$ symmetry. We determine how the exact mode functions decompose into representations of this symmetry group. This extends earlier results on the low-frequency limit of the massless scalar case to finite frequencies and general spin. As an application, we numerically determine the parameters of the representations that appear in quasinormal modes. These results represent a first step to formulating a more precise mapping to a holographic dual conformal field theory for generic black holes.

A novel theory of $F(R)$ gravity with the Lagrangian density $\mathcal{L}=[R-(b/\beta )\arctan (\beta R)]/(2{\kappa }^2)$ is analyzed. Constant curvature solutions of the model are found, and the potential of the scalar field and the mass of a scalar degree of freedom in Einstein’s frame are derived. The cosmological parameters of the model are calculated, which are in agreement with the PLANCK data. Critical points for the de Sitter phase and the matter dominated epoch of autonomous equations are obtained and studied.

We study phenomena happening at the surface of a star in Eddington-inspired Born-Infeld (EiBI) gravity. The star is made of particles, which are effectively described by a polytropic fluid. The EiBI theory was known to have a pathology that singularities happen at a star surface. We suggest that the gravitational backreaction on the particles cures the problem. Strong tidal forces near the (surface) singularity modify the effective equation of state of the particles or make the surface be unstable depending on its matter contents. The geodesic deviation equations take after Hooke’s law, where its frequency squared is proportional to the scalar curvature at the surface. For a positive curvature, a particle collides with a probing wall more often and increases the pressure. With the increased pressure, the surface is no longer singular. For a negative curvature, the matters around the surface experience repulsions with infinite accelerations. Therefore, the EiBI gravity is saved from the pathology of a surface singularity.

We study the time variation of the apparent flux of cosmological point sources due to the transient weak lensing by dark matter microhaloes. Assuming a transverse motion of microhaloes with respect to our line of sight, we derive the correspondence between the temporal power spectrum of the weak lensing magnification and the spatial power spectrum of density on small scales. Considering different approximations for the small-scale structure of dark matter, we predict the apparent magnitude of cosmological point sources to vary by as much as $10^{-4}-10^{-3}$, due to this effect, within a period of a few months. This red photometric noise has an almost perfect Gaussian statistics, to one part in $\sim 10^4$. We also compare the transient weak lensing power spectrum with the background effects such as the stellar microlensing on cosmological scales. A quasar lensed by a galaxy or cluster like a $\mathrm{SDSSJ}1004+4112$ strong lensing system, with multiple images, is a suitable system for this study because (i) using the time-delay method between different images, we can remove the intrinsic variations of the quasar, and (ii) strong lensing enhances signals from the transient weak lensing. We also require the images to form at large angular separations from the center of the lensing structure, in order to minimize contamination by the stellar microlensing. With long-term monitoring of quasar strong lensing systems with a 10-meter class telescope, we can examine the existence of dark microhaloes as the building blocks of dark matter structures. Failure to detect this signal may either be caused by a breakdown of cold dark matter (CDM) hierarchy on small scales, or rather interpreted as evidence against a CDM paradigm, e.g., in favor of modified gravity models.

The formation of the microwave background polarization anisotropies is investigated when the stochastic Faraday rate is stationary, random and Markovian. The scaling properties of the polarization power spectra and of their nonlinear combinations are scrutinized as a function of the comoving frequency. It is argued that each frequency channel of a given experiment measuring simultaneously the E-mode and the B-mode spectra can be analyzed in this framework with the aim of testing the physical origin of the polarization in a model-independent perspective.

In an era of increasingly advanced experimental analysis techniques it is crucial to understand which phase space regions contribute a signal extraction from backgrounds. Based on the Neyman-Pearson lemma we compute the maximum significance for a signal extraction as an integral over phase space regions. We then study to what degree boosted Higgs strategies benefit $ZH$ and $t\overline{t}H$ searches and which transverse momenta of the Higgs are most promising. We find that Higgs and top taggers are the appropriate tools, but would profit from a targeted optimization towards smaller transverse momenta. MadMax is available as an add-on to MadGraph 5.

We present predictions for Higgs production via gluon fusion with a $p_T$ veto on jets and with the resummation of jet-veto logarithms at ${\mathrm{NNLL}}^{\prime }+\mathrm{NNLO}$ order. These results incorporate explicit $\mathcal{O}({\alpha }_s^2)$ calculations of soft and beam functions, which include the dominant dependence on the jet radius $R$. In particular the ${\mathrm{NNLL}}^{\prime }$ order accounts for the correct boundary conditions for the $\mathrm{N}{}^3\mathrm{LL}$ resummation, for which the only unknown ingredients are higher-order anomalous dimensions. We use scale variations in a factorization theorem in both rapidity and virtuality space to estimate the perturbative uncertainties, accounting for both higher fixed-order corrections as well as higher-order towers of jet-$p_T$ logarithms. This formalism also predicts the correlations in the theory uncertainty between the exclusive 0-jet and inclusive 1-jet bins. At the values of $R$ used experimentally, there are important corrections due to jet algorithm clustering that include logarithms of $R$. Although we do not sum logarithms of $R$, we do include an explicit contribution in our uncertainty estimate to account for higher-order jet clustering logarithms. Precision predictions for this $H+0$-jet cross section and its theoretical uncertainty are an integral part of Higgs analyses that employ jet binning.

We study dark matter that inelastically scatters and deexcites in direct detection experiments, as an interpretation of the CDMS-Si events in light of the recent LUX data. The constraints from LUX and XENON10 require the mass splitting between the DM excited and deexcited states to be $|\delta |\gtrsim 50\mathrm{keV}$. At the same time, the CDMS-Si data themselves do not allow for a consistent DM interpretation for mass splittings larger than $|\delta |\sim 200\mathrm{keV}$. We find that a low-threshold analysis will be needed to rule out this interpretation of the CDMS-Si events. In a simple model with a kinetically mixed dark photon, we show that the CDMS-Si rate and the thermal relic abundance can both be accommodated.

If spacetime is built out of quantum bits, does the shape of space depend on how the bits are entangled? The $\mathrm{ER}=\mathrm{EPR}$ conjecture relates the entanglement entropy of a collection of black holes to the cross sectional area of Einstein-Rosen (ER) bridges (or wormholes) connecting them. We show that the geometrical entropy of classical ER bridges satisfies the subadditivity, triangle, strong subadditivity, and Cadney-Linden-Winter inequalities. These are nontrivial properties of entanglement entropy, so this is evidence for $\mathrm{ER}=\mathrm{EPR}$. We further show that the entanglement entropy associated with classical ER bridges has nonpositive tripartite information. This is not a property of entanglement entropy, in general. For example, the entangled four qubit pure state $|GH{Z}_4⟩=(|0000⟩+|1111⟩)/\sqrt{2}$ has positive tripartite information, so this state cannot be described by a classical ER bridge. Large black holes with massive amounts of entanglement between them can fail to have a classical ER bridge if they are built out of $|GH{Z}_4⟩$ states. States with nonpositive tripartite information are called monogamous. We conclude that classical ER bridges require monogamous EPR correlations.

The inverse stellar structure problem determines the equation of state of the matter in stars from a knowledge of their macroscopic observables (e.g. their masses and radii). This problem was solved in a previous paper by constructing a spectral representation of the equation of state whose stellar models match a prescribed set of macroscopic observables. This paper improves and extends that work in two significant ways. (i) The method is made more robust by accounting for an unexpected feature of the enthalpy-based representations of the equations of state used in this work. After making the appropriate modifications, accurate initial guesses for the spectral parameters are no longer needed, so Monte Carlo techniques can now be used to ensure the best fit to the observables. (ii) The method is extended here to use masses and tidal deformabilities (which will be measured by gravitational wave observations of neutron-star mergers) as the macroscopic observables instead of masses and radii. The accuracy and reliability of this extended and more robust spectral method is evaluated in this paper using mock data for observables from stars based on 34 different theoretical models of the high-density neutron-star equation of state. In qualitative agreement with earlier work, these tests suggest the high-density part of the neutron-star equation of state could be determined at the few-percent accuracy level using high-quality measurements of the masses and radii (or masses and tidal deformabilities) of just two or three neutron stars.

We show that the presence of a nonminimal interaction between dark matter and dark energy may lead to a violation of the null energy condition and to the formation of a configuration with nontrivial topology (a wormhole). In this it is assumed that both dark matter and dark energy satisfy the null energy condition, a violation of which takes place only in the inner high-density regions of the configuration. This is achieved by assuming that, in a high-density environment, a nonminimal coupling function changes its sign in comparison with the case where dark matter and dark energy have relatively low densities which are typical for a cosmological background. For this case, we find regular static, spherically symmetric solutions describing wormholes supported by dark matter nonminimally coupled to dark energy in the form of a quintessence scalar field.

Cold dark matter halos form within a smoothly distributed background of relic neutrinos—at least some of which are massive and nonrelativistic at late times. We calculate the accumulation of massive neutrinos around spherically collapsing cold dark matter halos in a cosmological background. We identify the physical extent of the “neutrino halo” in the spherical collapse model, which is large in comparison with the virial radius of the dark matter, and conditions under which neutrinos reaching the cold dark matter halo will remain bound to the halo at late times. We calculate the total neutrino mass and bound neutrino mass associated with isolated spherical halos for several neutrino mass hierarchies and provide fitting formulas for these quantities in terms of the cold dark matter halo mass and the masses of the individual neutrino species.

The brane-world scenario provides an intriguing possibility to explore the phenomenological cosmology implied by string/M theory. In this paper, we consider a modified Randall-Sundrum single brane model with two natural generalizations: a Gauss-Bonnet term in the five-dimensional bulk action as well as an induced gravity term in the four-dimensional brane action, which are the leading-order corrections to the Randall-Sundrum model. We study the influence of these combined effects on the evolution of the primordial gravitational waves generated during an extreme slow-roll inflation on the brane. The background, for the early inflationary era, is then modeled through a de Sitter brane embedded within an anti–de Sitter bulk. In this framework, we show that both effects tend to suppress the Randall-Sundrum enhancement of the amplitude of the tensor perturbations at relatively high energies. Moreover, the Gauss-Bonnet effect, relative to standard general relativity, will abruptly enhance the tensor-to-scalar ratio and break the standard consistency relation at high energies, which cannot be evaded by invoking the induced gravity effect, even though the induced gravity strength would mildly counterbalance these significant changes at high energies. We note that the brane-world model with or without the induced gravity effect fulfills the consistency relation. Finally, we discuss some implications of the observational constraints.

Generation of primordial magnetic fields during inflation typically requires the breaking of conformal invariance of the electromagnetic action. In this paper this has been achieved naturally in a higher-dimensional cosmological model with a Gauss-Bonnet term in the action. The evolution of the scale factor of the extra dimension (whose dynamics is influenced by the Gauss-Bonnet term) acts as the cause for the breaking of conformal invariance. Different cases have been investigated, each of which is characterized by the number of higher dimensions, the value of the Gauss-Bonnet parameter, and the cosmological constant. Many of the scenarios considered are highly constrained by the requirements that the cosmic evolution is stable, that the normal dimensions expand, and that there is no backreaction due to growing electric fields. However, there do exist scenarios which satisfy the above requirements and are well suited for magnetogenesis. In particular, a scenario where the number of extra dimensions $D=4$ and the cosmological constant is nonzero turns out to be best suited for generating primordial magnetic fields. It is shown that for these values of parameters, a scale-invariant magnetic field of the order of $10^{-10}–10^{-9}\mathrm{G}$ can be produced. Even in these most favorable scenarios, the higher-dimensional space expands during inflation at the same rate as the normal dimension. Hence, if a mechanism could freeze the evolution of the higher dimension, this seems to be a viable mechanism to produce acceptable primordial magnetic fields.

We argue that Witten’s loop mechanism for the right-handed Majorana neutrino mass generation identified originally in the $SO(10)$ grand unification context can be successfully adopted to the class of the simplest flipped $SU(5)$ models. In such a framework, the main drawback of the $SO(10)$ prototype—in particular, the generic tension among the gauge unification constraints and the absolute neutrino mass scale—is alleviated, and a simple yet potentially realistic and testable scenario emerges.