The recent long-term shutdown of Japanese nuclear reactors has resulted in a significantly reduced reactor ${\overline{\nu }}_e$ flux at KamLAND. This running condition provides a unique opportunity to confirm and constrain backgrounds for the reactor ${\overline{\nu }}_e$ oscillation analysis. The data set also has improved sensitivity for other ${\overline{\nu }}_e$ signals, in particular ${\overline{\nu }}_e$’s produced in $\beta$-decays from ${}^{238}\mathrm{U}$ and ${}^{232}\mathrm{Th}$ within the Earth’s interior, whose energy spectrum overlaps with that of reactor ${\overline{\nu }}_e$’s. Including constraints on ${\theta }_{13}$ from accelerator and short-baseline reactor neutrino experiments, a combined three-flavor analysis of solar and KamLAND data gives fit values for the oscillation parameters of ${tan}^2{\theta }_{12}={0.436}_{-0.025}^{+0.029}$, $\Delta m_{21}^2={7.53}_{-0.18}^{+0.18}\times {10}^{-5}{\mathrm{eV}}^2$, and ${sin}^2{\theta }_{13}={0.023}_{-0.002}^{+0.002}$. Assuming a chondritic Th/U mass ratio, we obtain ${116}_{-27}^{+28}$ ${\overline{\nu }}_e$ events from ${}^{238}\mathrm{U}$ and ${}^{232}\mathrm{Th}$, corresponding to a geo ${\overline{\nu }}_e$ flux of ${3.4}_{-0.8}^{+0.8}\times {10}^6{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}$ at the KamLAND location. We evaluate various bulk silicate Earth composition models using the observed geo ${\overline{\nu }}_e$ rate.

The largest sample ever recorded of ${\overline{\nu }}_{\mu }$ charged-current quasielastic (CCQE, ${\overline{\nu }}_{\mu }+p\to {\mu }^{+}+n$) candidate events is used to produce the minimally model-dependent, flux-integrated double-differential cross section $\frac{d^2\sigma }{d{T}_{\mu }d\cos {\theta }_{\mu }}$ for ${\overline{\nu }}_{\mu }$ CCQE for a mineral oil target. This measurement exploits the large statistics of the MiniBooNE antineutrino mode sample and provides the most complete information of this process to date. In order to facilitate historical comparisons, the flux-unfolded total cross section $\sigma (E_{\nu })$ and single-differential cross section $\frac{d\sigma }{d{Q}^2}$ on both mineral oil and on carbon are also reported. The observed cross section is somewhat higher than the predicted cross section from a model assuming independently acting nucleons in carbon with canonical form factor values. The shape of the data are also discrepant with this model. These results have implications for intranuclear processes and can help constrain signal and background processes for future neutrino oscillation measurements.

This work deals with braneworld scenarios obtained from $N$ real scalar fields, whose dynamics is generalized to include higher-order power in the derivative of the fields. For the scalar fields being driven by nonstandard dynamics, we show how a first-order formalism can be obtained for a flat brane in the presence of several fields. We then illustrate our findings, investigating distinct potentials with one and two fields, and obtaining stable standard and compact solutions in the braneworld theory. In particular, we have found different models describing the very same warp factor.

The analytic structure of solutions to the Klein-Gordon equation in a black hole background, as represented by monodromy data, is intimately related to black hole thermodynamics. It encodes the “hidden conformal symmetry” of a nonextremal black hole, and it explains why features of the inner event horizon appear in scattering data such as greybody factors. This indicates that hidden conformal symmetry is generic within a universality class of black holes.

According to the no-hair theorem, astrophysical black holes are uniquely characterized by their masses and spins and are described by the Kerr metric. Several parametric spacetimes that deviate from the Kerr metric have been proposed in order to test this theorem with observations of black holes in both the electromagnetic and gravitational-wave spectra. Such metrics often contain naked singularities or closed timelike curves in the vicinity of the compact objects, which can limit the applicability of the metrics to compact objects that do not spin rapidly, and generally admit only two constants of motion. The existence of a third constant, however, can facilitate the calculation of observables, because the equations of motion can be written in first-order form. In this paper, I design a Kerr-like black hole metric which is regular everywhere outside of the event horizon, possesses three independent constants of motion, and depends nonlinearly on four free functions that parametrize potential deviations from the Kerr metric. This metric is generally not a solution to the field equations of any particular gravity theory, but can be mapped to known four-dimensional black hole solutions of modified theories of gravity for suitable choices of the deviation functions. I derive expressions for the energy, angular momentum, and epicyclic frequencies of a particle on a circular equatorial orbit around the black hole and compute the location of the innermost stable circular orbit. In addition, I write the metric in a Kerr-Schild-like form, which allows for a straightforward implementation of fully relativistic magnetohydrodynamic simulations of accretion flows in this metric. The properties of this metric make it a well-suited spacetime for strong-field tests of the no-hair theorem in the electromagnetic spectrum with black holes of arbitrary spin.

We propose an improved analytical model for the horizon-absorbed gravitational-wave energy flux of a small body in circular orbit in the equatorial plane of a Kerr black hole. Post-Newtonian (PN) theory provides an analytical description of the multipolar components of the absorption flux through Taylor expansions in the orbital frequency. Building on previous work, we construct a mode-by-mode factorization of the absorbed flux whose Taylor expansion agrees with current PN results. This factorized form significantly improves the agreement with numerical results obtained with a frequency-domain Teukolsky code, which evolves through a sequence of circular orbits up to the photon orbit. We perform the comparison between model and numerical data for dimensionless Kerr spins $-0.99\le q\le 0.99$ and for frequencies up to the light ring of the Kerr black hole. Our proposed model enforces the presence of a zero in the flux at an orbital frequency equal to the frequency of the horizon, as predicted by perturbation theory. It also reproduces the expected divergence of the flux close to the light ring. Neither of these features are captured by the Taylor-expanded PN flux. Our proposed absorption flux can also help improve models for the inspiral, merger, ringdown of small mass-ratio binary systems.

We investigate spherically symmetric spacetimes with an anisotropic fluid and discuss the existence and stability of a separating shell dividing expanding and collapsing regions. We resort to a $3+1$ splitting and obtain gauge invariant conditions relating intrinsic spacetime quantities to properties of the matter source. We find that the separating shell is defined by a generalization of the Tolman-Oppenheimer-Volkoff equilibrium condition. The latter establishes a balance between the pressure gradients, both isotropic and anisotropic, and the strength of the fields induced by the Misner-Sharp mass inside the separating shell and by the pressure fluxes. This defines a local equilibrium condition, but conveys also a nonlocal character given the definition of the Misner-Sharp mass. By the same token, it is also a generalized thermodynamical equation of state as usually interpreted for the perfect fluid case, which now has the novel feature of involving both the isotropic and the anisotropic stresses. We have cast the governing equations in terms of local, gauge invariant quantities that are revealing of the role played by the anisotropic pressures and inhomogeneous electric part of the Weyl tensor. We analyze a particular solution with dust and radiation that provides an illustration of our conditions. In addition, our gauge invariant formalism not only encompasses the cracking process from Herrera and co-workers but also reveals transparently the interplay and importance of the shear and of the anisotropic stresses.

An interesting mass relation between down-type quarks and charged leptons has been recently predicted within a supersymmetric $\mathrm{SU}(3{)}_{\mathrm{c}}\otimes \mathrm{SU}(2{)}_{\mathrm{L}}\otimes \mathrm{U}(1{)}_{\mathrm{Y}}$ model based on the $A_4$ flavor symmetry. Here we propose a simple extension which provides an adequate full description of the quark sector. By adding a pair of vectorlike up quarks, we show how the CKM entries $V_{ub}$, $V_{cb}$, $V_{td}$ and $V_{ts}$ arise from deviations of the unitarity. We perform an analysis including the most relevant observables in the quark sector, such as oscillations and rare decays of kaons, $B_d$ and $B_s$ mesons. In the lepton sector, the model predicts an inverted hierarchy for the neutrino masses, leading to a potentially observable rate of neutrinoless double beta decay.

We investigate a simple model where lepton number is promoted to a local $\mathrm{U}(1{)}_L$ gauge symmetry which is then spontaneously broken, leading to a viable thermal dark matter (DM) candidate and vectorlike leptons as a byproduct. The dark matter arises as part of the exotic lepton sector required by the need to satisfy anomaly cancellation and is a Dirac electroweak (mostly) singlet neutrino. It is stabilized by an accidental global symmetry of the renormalizable Lagrangian which is preserved even after the gauged lepton number is spontaneously broken and can annihilate efficiently to give the correct thermal relic abundance. We examine the ability of this model to give a viable DM candidate and discuss both direct and indirect detection implications. We also examine some of the LHC phenomenology of the associated exotic lepton sector and in particular its effects on Higgs decays.

In this work, we study a generalization of the Randall-Sundrum model which yields new warp factors. In this model, as a result, the strong brane is also constrained to have a tension of positive sign. In addition, new relations between the coupling constants ${\kappa }_4$ and ${\kappa }_5$ and between the Higgs and Planck masses are obtained.

We study linear responses of D0-branes in the low frequency region by using gauge/gravity correspondence. The dynamics of the D0-branes is described by matrix theory with finite temperature, which is dual to a near extremal D0-brane black hole solution. We analyze the tensor mode and vector modes of a stress tensor and a Ramond-Ramond 1-form current of matrix theory. Then, we show that if a cutoff surface is close to a horizon of the D0-brane black hole, the linear responses take forms similar to the hydrodynamic stress tensor and current on $S^8$. By taking a Rindler limit, those linear responses come to obey the hydrodynamics exactly, which is consistent with previous works on a Rindler fluid. We also show that if the cutoff surface is far from the horizon, the linear responses do not take the forms of the hydrodynamic stress tensor and current on $S^8$. Especially, we find that the vector modes no longer possess a diffusion pole in the low frequency region, which indicates that the linear responses of the D0-branes cannot be explained by hydrodynamics.

We determine the thermodynamic properties of a class of spherically symmetric and static black holes in ${\mathrm{AdS}}_4$ with magnetic charges and scalar hair. These black holes are solutions in four-dimensional $N=2$ gauged supergravity that can arise from 11-dimensional supergravity compactified on ${\mathrm{S}}^7$. At zero temperature, they preserve supersymmetry and hence are stable. At nonzero temperatures, we explore in detail the canonical ensemble and stability of solutions and find a first-order phase transition between small and large hairy black holes. The transition emerges as a liquid-gas phase transition in the dual three-dimensional field theory on $\mathbb{R}\times {\mathrm{S}}^2$ with magnetic flux through ${\mathrm{S}}^2$.

We establish the equivalence between the continuum limit of the quantum spherical model with competing interactions, which is relevant to the investigation of Lifshitz points, and the $O(N)$ nonlinear sigma model with the addition of higher order spatial derivative operators, which breaks the Lorentz symmetry and is known as Lifshitz-type (or anisotropic) nonlinear sigma model. In the context of the $1/N$ expansion, we also discuss the renormalization properties of this nonlinear sigma model and find the nontrivial fixed points of the $\beta$ functions in various dimensions, which turn out to be connected with the existence of phase transitions in the quantum spherical model.

In 1936, Weisskopf [K. Dan. Vidensk. Selsk. Mat. Fys. Medd. XIV (1936)] showed that for vanishing electric or magnetic fields the strong-field behavior of the one-loop Euler-Heisenberg effective Lagrangian of quantum electro dynamics (QED) is logarithmic. Here we generalize this result for different limits of the Lorentz invariants ${\overrightarrow{E}}^2-{\overrightarrow{B}}^2$ and $\overrightarrow{B}·\overrightarrow{E}$. The logarithmic dependence can be interpreted as a lowest-order manifestation of an anomalous power behavior of the effective Lagrangian of QED, with critical exponents $\delta =e^2/(12\pi )$ for spinor QED, and ${\delta }_S=\delta /4$ for scalar QED.

So far analysis of the quasinormal spectrum of a massive charged scalar field in the black hole background has been limited by the regime of small $\mu M$ and $qQ$, where $\mu$, $q$ $(M,Q)$ are mass and charge of the field (black hole). Here we shall present a comprehensive picture of quasinormal modes, late-time tails and stability of a massive charged scalar field around Kerr-Newman black holes for any physically meaningful values of the parameters. We shall show that despite the presence of the two mechanisms of superradiance (owing to black hole’s rotation and charge) and the massive term creating growing bound states, there is no indication of instability under the quasinormal modes’ boundary conditions. We have shown that for some moderate values of $qQ$ dominant quasinormal modes may have arbitrarily small real oscillation frequencies $\mathrm{Re}(\omega )$. An analytic formula for the quasinormal modes has been derived in the regime of large $qQ$. The larger the field’s charge, the sooner asymptotic tails dominate in a signal, making it difficult to extract quasinormal frequencies from a time-domain profile. Analytic expressions for intermediate and asymptotically late-time tails have been found for the Reissner-Nordström black hole. For the near extremal Kerr-Newman black holes we have obtained a more general picture of the mode branching found recently for massless fields [arXiv:1212.3271] in the Kerr background.

We study time-independent, spherically symmetric, self-gravitating systems minimally coupled to a scalar field with $U(1)$ gauge symmetry: charged boson stars. We find numerical solutions to the Einstein-Maxwell equations coupled to the relativistic Klein-Gordon equation. It is shown that bound stable configurations exist only for values of the coupling constant less than or equal to a certain critical value. The metric coefficients and the relevant physical quantities, such as the total mass and charge, turn out to be, in general, bound functions of the radial coordinate, reaching their maximum values at a critical value of the scalar field at the origin. We discuss the stability problem from both the quantitative and qualitative point of view. We take into account the electromagnetic contribution to the total mass and investigate the stability issue considering the binding energy per particle. We verify the existence of configurations with positive binding energy in which objects that are apparently bound can be unstable against small perturbations, in full analogy with the effect observed in the mass-radius relation of neutron stars.

We investigate particular cosmological models, based either on tachyon fields or on perfect fluids, for which soft future singularities arise in a natural way. Our main result is the description of a smooth crossing of the soft singularity in models with an anti-Chaplygin gas or with a particular tachyon field in the presence of dust. Such a crossing is made possible by certain transformations of matter properties. Some of these cosmological evolutions involving tachyons are compatible with SNIa data. We compute numerically their dynamics involving a first soft singularity crossing, a turning point and a second soft singulatity crossing during recollapse, ending in a Big Crunch singularity.

We investigate in this paper the antideuteron flux produced in high energy collisions of cosmic rays with interstellar matter. We employ a modified version of the Monte Carlo generator DPMJET-III together with the coalescence model to simulate, in an event-by-event basis, the antideuteron production in cosmic ray collisions in our Galaxy. Then, we use a diffusion model to calculate the expected flux. We find a secondary antideuteron flux at the Earth with a central value which is a factor of 2 smaller than in previous calculations, although still affected by large uncertainties due to the antideuteron production and propagation.

We study quantum critical behavior in three dimensional lattice Gross-Neveu models containing two four-component massless Dirac fermions. We focus on two models with $SU(2)$ flavor symmetry and either a $Z_2$ or a $U(1)$ chiral symmetry. Both models could not be studied earlier due to sign problems. We use the fermion bag approach which is free of sign problems and compute critical exponents at the phase transitions. We estimate $\nu =0.83(1)$, $\eta =0.62(1)$, ${\eta }_{\psi }=0.38(1)$ in the $Z_2$ and $\nu =0.849(8)$, $\eta =0.633(8)$, ${\eta }_{\psi }=0.373(3)$ in the $U(1)$ model.

We study several phenomenologies of an $E_6$-inspired extra $U(1)$ model with $S_4$ flavor symmetry. With the assignment of left-handed quarks and leptons to $S_4$ doublets, the supersymmetry flavor problem is softened. As the extra Higgs bosons are neutrinophilic, baryon number asymmetry in the Universe is realized by leptogenesis without causing gravitino overproduction. We find that the allowed region for the lightest chargino mass is given by 100–140 GeV, if the dark matter is a singlino-dominated neutralino whose mass is about 36 GeV.