The regularized stress-energy tensor of the quantized massive scalar, spinor, and vector fields inside the degenerate horizon of the regular charged black hole in the (anti)-de Sitter universe is constructed and examined. It is shown that, although the components of the stress-energy tensor are small in the vicinity of the black hole degenerate horizon and near the regular center, they are quite big in the intermediate region. The oscillatory character of the stress-energy tensor can be ascribed to various responses of the higher curvature terms to the changes of the metric inside the (degenerate) event horizon, especially in the region adjacent to the region described by the nearly flat metric potentials. Special emphasis is put on the stress-energy tensor in the geometries being the product of the constant curvature two-dimensional subspaces.

We investigate constraints on primordial black holes (PBHs) as dark matter candidates that arise from their capture by neutron stars (NSs). If a PBH is captured by a NS, the star is accreted onto the PBH and gets destroyed in a very short time. Thus, mere observations of NSs put limits on the abundance of PBHs. High DM densities and low velocities are required to constrain the fraction of PBHs in DM. Such conditions may be realized in the cores of globular clusters if the latter are of a primordial origin. Assuming that cores of globular clusters possess the DM densities exceeding several hundred $\mathrm{GeV}/{\mathrm{cm}}^3$ would imply that PBHs are excluded as comprising all of the dark matter in the mass range $3\times {10}^{18}\lesssim m_{\mathrm{BH}}\lesssim {10}^{24}\mathrm{g}$. At the DM density of $2\times {10}^3\mathrm{GeV}/{\mathrm{cm}}^3$ that has been found in simulations in the corresponding models, less than 5% of the DM may consist of PBH for these PBH masses.

It is crucial to understand and model a behavior of galaxy biasing for future ambitious galaxy redshift surveys. Using 40 large cosmological $N$-body simulations for a standard $\Lambda \mathrm{CDM}$ cosmology, we study the cross-correlation coefficient between matter and the halo density field, which is an indicator of the stochasticity of bias, over a wide redshift range $0\le z\le 3$. The cross-correlation coefficient is important to extract information on the matter density field, e.g., by combining galaxy clustering and galaxy-galaxy lensing measurements. We compare the simulation results with integrated perturbation theory (iPT) proposed by one of the present authors and standard perturbation theory combined with a phenomenological model of local bias. The cross-correlation coefficient derived from the iPT agrees with $N$-body simulation results down to $r\sim 15(10)h^{-1}\mathrm{Mpc}$ within 0.5 (1.0)% for all redshifts and halo masses we consider. The standard perturbation theory with local bias does not explain complicated behaviors on quasilinear scales at low redshifts, while roughly reproduces the general behavior of the cross-correlation coefficient on fully nonlinear scales. The iPT is powerful to predict the cross-correlation coefficient down to quasilinear regimes with a high precision.

We study the possibly existing anisotropy in the accelerating expansion Universe with the Union2 type Ia supernovae data and gamma-ray burst data. We construct a direction-dependent dark energy model and constrain the anisotropy direction and strength of modulation. We find that the maximum anisotropic deviation direction is $(l,b)=(126°,13°)$ [or, equivalently, $(l,b)=(306°,-13°)$], and the current anisotropy level is $g_0={0.030}_{+0.010}^{-0.030}$ ($1\sigma$ confidence level with Union2 data). Our results do not show strong evidence for the anisotropic dark energy model. We also discuss potential methods that may distinguish the peculiar velocity field from the anisotropic dark energy model.

Many new physics models predict the existence of an extra neutral gauge boson ($Z^{\prime }$). Inspired by the recent development in the Higgs search, we study the properties of $Z^{\prime }$ via the Higgs and $Z$-boson associated production. The couplings of $Z^{\prime }$ to quarks can be investigated through the $pp\to Z^{\prime }\to ZH\to l^{+}{l}^{-}b\overline{b}$ process, which also provides an extraordinary signal for understanding the properties of the $Z^{\prime }ZH$ interaction. The standard model background processes can be significantly suppressed by adopting appropriate kinematic cuts. The charged lepton angular distributions are related to the ratio of the chiral couplings of $Z^{\prime }$ to quarks via the $Z^{\prime }ZH$ interaction.

Supersymmetric unified models in which the $Z^{\prime }$ couples to the Higgs doublets, as in the $E_6$ class of models, have large fine tuning dominated by the experimental mass limit on the $Z^{\prime }$. To illustrate this, we investigate the degree of fine tuning throughout the parameter space of the constrained exceptional supersymmetric standard model (${\mathrm{cE}}_6\mathrm{SSM}$) that is consistent with a Higgs mass $m_h\sim 125\mathrm{GeV}$. Fixing $\tan \beta =10$, and taking specific values of the mass of the $Z^{\prime }$ boson, with $M_{Z^{\prime }}\sim 2–4\mathrm{TeV}$, we find that the minimum fine tuning is set predominantly from the mass of $Z^{\prime }$ and varies from $\sim 200$ to 400 as we vary $M_{Z^{\prime }}$ from $\sim 2$ to 4 TeV. However, this is significantly lower than the fine tuning in the constrained minimal supersymmetric standard model, of $\mathcal{O}(1000)$, arising from the large stop masses required to achieve the Higgs mass.

We study $1\pi$ production in both charged and neutral current neutrino-nucleus scattering for neutrino energies below 2 GeV. We use a theoretical model for one pion production at the nucleon level that we correct for medium effects. The results are incorporated into a cascade program that apart from production also includes the pion final state interaction inside the nucleus. Besides, in some specific channels coherent $\pi$ production is also possible and we evaluate its contribution as well. Our results for total and differential cross sections are compared with recent data from the MiniBooNE Collaboration. The model provides an overall acceptable description of the data, better for neutral-current than for charged-current channels, although the theory is systematically below the data. Differential cross sections, folded with the full neutrino flux, show that most of the missing pions lie in the forward direction and at high energies.

Flavor mixings together with fermion mass spectra are studied in detail in the $SU(6)\times SU(2{)}_R$ model, in which state-mixings beyond the minimal supersymmetric standard model (MSSM) take place. Characteristic patterns of fermion spectra are attributed to the hierarchical structure of effective Yukawa interactions via the Froggatt-Nielsen mechanism and also to the state-mixings beyond the MSSM. It is shown explicitly that the neutrino mass matrix in the mass diagonal basis for charged leptons has no hierarchical structure. This is due to the cancellation among the hierarchical factors by the seesaw mechanism with the hierarchical Majorana mass matrix of $R$-handed neutrinos. As a consequence, $V_{\mathrm{MNS}}$ exhibits large mixing. It is found that observed values of the Maki-Nakagawa-Sakata matrix elements are reproduced successfully.

By analyzing data samples of $2.9{\mathrm{fb}}^{-1}$ collected at $\sqrt{s}=3.773\mathrm{GeV}$, $482{\mathrm{pb}}^{-1}$ collected at $\sqrt{s}=4.009\mathrm{GeV}$ and $67{\mathrm{pb}}^{-1}$ collected at $\sqrt{s}=3.542$, 3.554, 3.561, 3.600 and 3.650 GeV with the BESIII detector at the BEPCII storage ring, we search for $\psi (3770)$ and $\psi (4040)$ decay to baryonic final states, including $\Lambda \overline{\Lambda }{\pi }^{+}{\pi }^{-}$, $\Lambda \overline{\Lambda }{\pi }^0$, $\Lambda \overline{\Lambda }\eta$, ${\Sigma }^{+}{\overline{\Sigma }}^{-}$, ${\Sigma }^0{\overline{\Sigma }}^0$, ${\Xi }^{-}{\overline{\Xi }}^{+}$ and ${\Xi }^0{\overline{\Xi }}^0$ decays. None are observed, and upper limits are set at the 90% confidence level.

The time-dependent $CP$ asymmetry in $B_s^0\to J/\psi K^{+}{K}^{-}$ decays is measured using $pp$ collision data at $\sqrt{s}=7\mathrm{TeV}$, corresponding to an integrated luminosity of $1.0{\mathrm{fb}}^{-1}$, collected with the LHCb detector. The decay-time distribution is characterized by the decay widths ${\Gamma }_{\mathrm{L}}$ and ${\Gamma }_{\mathrm{H}}$ of the light and heavy mass eigenstates of the $B_s^0\mathrm{\text{−}}{\overline{B}}_s^0$ system and by a $CP$-violating phase ${\varphi }_s$. In a sample of 27 617 $B_s^0\to J/\psi K^{+}{K}^{-}$ decays, where the dominant contribution comes from $B_s^0\to J/\psi \varphi$ decays, these parameters are measured to be ${\varphi }_s=0.07\pm 0.09(\mathrm{stat})\pm 0.01(\mathrm{syst})\mathrm{rad}$, ${\Gamma }_s\equiv ({\Gamma }_{\mathrm{L}}+{\Gamma }_{\mathrm{H}})/2=0.663\pm 0.005(\mathrm{stat})\pm 0.006(\mathrm{syst}){\mathrm{ps}}^{-1}$, and $\Delta {\Gamma }_s\equiv {\Gamma }_{\mathrm{L}}-{\Gamma }_{\mathrm{H}}=0.100\pm 0.016(\mathrm{stat})\pm 0.003(\mathrm{syst}){\mathrm{ps}}^{-1}$, corresponding to the single most precise determination of ${\varphi }_s$, $\Delta {\Gamma }_s$, and ${\Gamma }_s$. The result of performing a combined analysis with $B_s^0\to J/\psi {\pi }^{+}{\pi }^{-}$ decays gives ${\varphi }_s=0.01\pm 0.07(\mathrm{stat})\pm 0.01(\mathrm{syst})\mathrm{rad}$, ${\Gamma }_s=0.661\pm 0.004(\mathrm{stat})\pm 0.006(\mathrm{syst}){\mathrm{ps}}^{-1}$, and $\Delta {\Gamma }_s=0.106\pm 0.011(\mathrm{stat})\pm 0.007(\mathrm{syst}){\mathrm{ps}}^{-1}$. All measurements are in agreement with the Standard Model predictions.

Axions in the presence of an external magnetic field can change the optical properties of the vacuum making the vacuum birefringent. If the field is inhomogeneous the two propagation modes gain an additional splitting along the direction of the field gradient, creating a Stern-Gerlach-type effect. We show here how in a mirror cavity this splitting results in bifurcation of the beam. We present the formalism that provides an effective model to study the photon-axion mixing in an inhomogeneous magnetic field. The measurable is a decrease in the light intensity of the central region. It is shown, with an appropriate mirror cavity and magnetic field, it is possible to achieve an order of magnitude beyond the CERN Axion Solar Telescope level for the coupling constant near the region of zero mass.

We show how a mass mixing matrix can be generated dynamically, for two massless fermion flavors coupled to a Lorentz invariance violating (LIV) gauge field. The LIV features play the role of a regulator for the gap equations, and the nonanalytic dependence of the dynamical masses, as functions of the gauge coupling, allows us to consider the limit where the LIV gauge field eventually decouples from the fermions. Lorentz invariance is then recovered, to describe the oscillation between two free fermion flavors, and we check that the finite dynamical masses are the only effects of the original LIV theory. We also discuss briefly a connection of our results with the case of Majorana neutrinos in both, the standard model, where only left-handed (active) neutrinos are considered, and extensions thereof, with sterile right-handed neutrinos.

The unitarity in Lorentz invariance violating QED consisting of standard fermions and higher-order photons of the Myers-Pospelov theory is studied. We find ghost states associated to the higher-order character of the theory which could render the $S$-matrix nonunitary. An explicit calculation to check perturbative unitarity in the process of electron-positron scattering is performed and it is found to be possible to preserve unitarity.

Recent nonlinear completions of Fierz-Pauli theory for a massive spin-2 field include nonlinear massive gravity and bimetric theories. The spectrum of black-hole solutions in these theories is rich and comprises the same vacuum solutions of Einstein’s gravity enlarged to include a cosmological constant. It was recently shown that Schwarzschild (de Sitter) black holes in these theories are generically unstable against spherical perturbations. Here we show that a notable exception is partially massless gravity, where the mass of the graviton is fixed in terms of the cosmological constant by ${\mu }^2=2\Lambda /3$ and a new gauge invariance emerges. We find that general relativity black holes are stable in this limit. Remarkably, the spectrum of massive gravitational perturbations is isospectral.

The near-horizon field $B$ of an old black hole is maximally entangled with the early Hawking radiation $R$, by unitarity of the S-matrix. But $B$ must be maximally entangled with the black hole interior $A$, by the equivalence principle. Causal patch complementarity fails to reconcile these conflicting requirements. The system $B$ can be probed by a freely falling observer while there is still time to turn around and remain outside the black hole. Therefore, the entangled state of the $BR$ system is dictated by unitarity even in the infalling patch. If, by monogamy of entanglement, $B$ is not entangled with $A$, the horizon is replaced by a singularity or “firewall.” To illustrate the radical nature of the ideas that are needed, I briefly discuss two approaches for avoiding a firewall: the identification of $A$ with a subsystem of $R$; and a combination of patch complementarity with the Horowitz-Maldacena final-state proposal.

Recently, several authors have studied the possibility of overspinning or overcharging an existing black hole to destroy its event horizon and make the central singularity naked. When all the effects are properly taken into account, any attempt to destroy the black hole seems to be doomed to fail, in agreement with the weak cosmic censorship conjecture. In this article, we study the possibility of destroying the event horizon of regular black holes. These objects have no central singularity and therefore they are not protected by the cosmic censorship hypothesis. Our results strongly support the conclusion that regular black holes can be destroyed. If we believe that the central singularity in astrophysical black holes is solved by quantum gravity effects, we might have a chance to see the black hole’s internal region and observe quantum gravity phenomena. As our finding implies the violation of the black hole’s area theorem, the collision of two black holes may release an amount of energy exceeding the Hawking bound, which can be experimentally tested by gravitational wave detectors.

The nature of dark matter is one of the most thrilling riddles for both cosmology and particle physics nowadays. While in the typical models the dark sector is composed only by weakly interacting massive particles, an arguably more natural scenario would include a whole set of gauge interactions which are invisible for the standard model but that are in contact with the dark matter. We present a method to constrain the number of massless gauge bosons and other relativistic particles that might be present in the dark sector using current and future cosmic microwave background data, and provide upper bounds on the size of the dark sector. We use the fact that the dark matter abundance depends on the strength of the interactions with both sectors, which allows one to relate the freeze-out temperature of the dark matter with the temperature of this cosmic background of dark gauge bosons. This relation can then be used to calculate how sizable is the impact of the relativistic dark sector in the number of degrees of freedom of the early Universe, providing an interesting and testable connection between cosmological data and direct/indirect detection experiments. The recent Planck data, in combination with other cosmic microwave background experiments and baryonic acoustic oscillations data, constrains the number of relativistic dark gauge bosons, when the freeze-out temperature of the dark matter is larger than the top mass, to be $N\lesssim 14$ for the simplest scenarios, while those limits are slightly relaxed for the combination with the Hubble constant measurements to $N\lesssim 20$. Future releases of Planck data are expected to reduce the uncertainty by approximately a factor of 3, which will reduce significantly the parameter space of allowed models.

The inflating curvaton can create curvature perturbation when the curvaton density is slowly varying. Using the delta-N formalism, we discuss the evolution of the curvature perturbation during curvaton inflation and find analytic formulation of the non-Gaussianity parameter. We first consider the inflating curvaton with sufficiently long inflationary expansion. Then we compare the result with short curvaton inflation.

We investigate the nucleosynthesis constraint on Lorentz invariance violation in the neutrino sector, which influences the formation of light elements by altering the energy density of the Universe and weak reaction rates prior to and during the big bang nucleosynthesis epoch. We derive the weak reaction rates in the Lorentz-violating extension of the standard model. Using measurements of the primordial helium-4 and deuterium abundances, we give a tighter constraint on the deformed parameter than that derived from measurements of the cosmic microwave background anisotropies.