The negative energy density of Casimir systems appears to violate general relativity energy conditions. However, one cannot test the averaged null energy condition (ANEC) using standard calculations for perfectly reflecting plates, because the null geodesic would have to pass through the plates, where the calculation breaks down. To avoid this problem, we compute the contribution to ANEC for a geodesic that passes through a hole in a single plate. We consider both Dirichlet and Neumann boundary conditions in two and three space dimensions. We use a Babinet’s principle argument to reduce the problem to a complementary finite disk correction to the perfect mirror result, which we then compute using scattering theory in elliptical and spheroidal coordinates. In the Dirichlet case, we find that the positive correction due to the hole overwhelms the negative contribution of the infinite plate. In the Neumann case, where the infinite plate gives a positive contribution, the hole contribution is smaller in magnitude, so again ANEC is obeyed. These results can be extended to the case of two plates in the limits of large and small hole radii. This system thus provides another example of a situation where ANEC turns out to be obeyed when one might expect it to be violated.

In a previous letter, we have observed that the infinities of the standard model (SM) are a source of Quantum Gravity effects at lower energies. This analysis implies the existence of Lorentz invariance violation (LIV) within the SM. In this paper we obtain the LIV for mesons and nucleons using chiral lagrangian and Heavy Baryon Chiral Perturbation Theory. We use them to study several effects, including the GZK anomaly.

Gravity on a brane world with higher order curvature terms and a conformally coupled bulk scalar field is investigated. Solutions with nonstandard large distance gravity are described. It is not necessary to include a scalar field potential in order to obtain the solutions. The resulting Newton potential is qualitatively similar to that of the Dvali-Gabadadze-Porrati (DGP) model. For suitable parameter choices the model is ghost free. Like many other brane gravity models with modified large distance Newton potentials, the short distance gravity is scalar-tensor. The scalar couples with gravitational strength, and so the model is not compatible with observation.

We study scalar field perturbations on the background of nonsupersymmetric black rings and of supersymmetric black rings. In the infinite-radius limit of these geometries, we are able to separate the wave equation, and to study wave phenomena in its vicinities. In this limit, we show that (i) the nonsupersymmetric case is stable against scalar field perturbations, (ii) the low energy absorption cross section for scalar fields is equal to the area of the event horizon in the supersymmetric case, and proportional to it in the nonsupersymmetric situation.

Brane-world models suggest modification of Newton’s law of gravity on the 3-brane at submillimeter scales. The brane-world induced corrections are in higher powers of inverse distance and appear as additional terms with the Newtonian potential. The average interparticle distance in white dwarf and neutron stars is ${10}^{-10}\mathrm{cms}$ and ${10}^{-13}\mathrm{cms}$, respectively, and therefore, the effect of submillimeter corrections needs to be investigated. We show, by carrying out simple many-body calculations, that the mass and mass-radius relationship of the white dwarf and neutron stars are not effected by submillimeter corrections. However, our analysis shows that the correction terms in the effective theory give rise to force akin to surface tension in normal liquids.

We compute the one loop self-mass-squared of a massless, minimally coupled scalar which is Yukawa-coupled to a massless Dirac fermion in a general conformally flat background. Dimensional regularization is employed and a fully renormalized result is obtained. For the special case of a locally de Sitter background our result is manifestly de Sitter invariant. By solving the effective field equations we show that the scalar mode functions acquire no significant one loop corrections. In particular, the phenomenon of superadiabatic amplification is not affected. One consequence is that the scalar-catalyzed production of fermions during inflation should not be reduced by changes in the scalar sector before it has time to go to completion.

Evaluating a functional integral exactly over a subset of metrics that represent the quantum fluctuations of the horizon of a black hole, we obtain a Schrödinger equation in null coordinate time for the key component of the metric. The equation yields a current that preserves probability if we use the most natural choice of functional measure. This establishes the existence of blurred horizons and a thermal atmosphere. It has been argued previously that the existence of a thermal atmosphere is a direct concomitant of the thermal radiation of black holes when the temperature of the hole is greater than that of its larger environment, which we take as zero.

We present techniques for successfully performing numerical relativity simulations of binary black holes with fourth-order accuracy. Our simulations are based on a new coding framework which currently supports higher-order finite differencing for the Baumgarte-Shapiro-Shibata-Nakamura formulation of Einstein’s equations, but which is designed to be readily applicable to a broad class of formulations. We apply our techniques to a standard set of numerical relativity test problems, demonstrating the fourth-order accuracy of the solutions. Finally we apply our approach to binary black hole head-on collisions, calculating the waveforms of gravitational radiation generated and demonstrating significant improvements in waveform accuracy over second-order methods with typically achievable numerical resolution.

Split supersymmetry scenarios with PeV-scale scalar masses circumvent many of the restrictions on supersymmetry coming from experimental limits on $CP$ violation, flavor-changing neutral currents, and the Higgs boson mass. We consider the situation where the lightest supersymmetric particle is either a $W$-ino or Higgsino and the majority of its cold dark-matter relic density is of thermal origin, in which case its mass is specified to be 2.3 TeV for a $W$-ino or 1.1 TeV for a Higgsino. We examine the potential for indirect detection, at present and future $\gamma$-ray telescopes, of the monoenergetic photon lines that would result from the annihilation of these particles near the galactic center. We show how the possibility for detection depends on the precise form of the galactic dark-matter halo profile and examine what performance attributes a $\gamma$-ray detector would need in order to register a $5\sigma$ discovery.

The dark energy universe equation of state (EOS) with inhomogeneous, Hubble parameter dependent term is considered. The motivation to introduce such a term comes from time-dependent viscosity considerations and modifications of general relativity. For several explicit examples of such EOS it is demonstrated how the type of future singularity changes, how the phantom epoch emerges and how the crossing of a phantom barrier occurs. Similar cosmological regimes are considered for the universe with two interacting fluids and for the universe with implicit EOS. For instance, the crossing of the phantom barrier is realized in an easier way, thanks to the presence of inhomogeneous term. The thermodynamical dark energy model is presented where the universe entropy may be positive even at the phantom era as a result of the crossing of the $w=-1$ barrier.

Status of investigations of the new observed charmed strange mesons $D_{SJ}^{\star }(2317{)}^{\pm }$, $D_{SJ}(2460{)}^{\pm }$ and $D_{SJ}(2632{)}^{+}$ is simply reviewed. A systemic classification to these states with Regge trajectories (RTs) was made. We found that $D_{SJ}^{\star }(2317{)}^{\pm }$ and $D_{SJ}(2460{)}^{\pm }$ are reasonable to be arranged as $(0^{+},1^{+})$ states, but $D_{SJ}(2632{)}^{+}$ seems not possible to be an orbital excited tensor particle. As a byproduct, the nonstrange charmed mesons including $D_1^{\prime }(2427)$ and $D^{\star }(2637{)}^{+}$ were analyzed also.

We present improved experimental bounds on typical length scales of a photon-propagation model with a frozen (time-independent) random background field, which could result from anomalous effects of a static, multiply connected spacetime foam.

We discuss how the cosmological baryon asymmetry can be achieved by the lepton family asymmetries of heavy Majorana neutrino decays and how the lepton family asymmetries are related to $CP$ violation in neutrino oscillation, in the minimal seesaw model with two heavy Majorana neutrinos. We derive the most general formula for $CP$ violation in neutrino oscillation in terms of the heavy Majorana masses and Yukawa mass term. It is shown that the formula is very useful to classify several models in which $e$, $\mu$, and $\tau$ leptogenesis can be separately realized and to see how they are connected with low energy $CP$ violation. To make the models predictive, we take texture with two zeros in the Dirac matrix. In particular, we find some interesting cases in which $CP$ violation in neutrino oscillation can happen while lepton family asymmetries do not exist at all. On the contrary, we can find $e$-, $\mu$-, and $\tau$-leptogenesis scenarios in which the cosmological $CP$ violation and low energy $CP$ violation measurable via neutrino oscillations are very closely related to each other. By determining the allowed ranges of the parameters in the models, we predict the sizes of $CP$ violation in neutrino oscillation and $|V_{e3}^{\mathrm{MNS}}|$. Finally, the leptonic unitarity triangles are reconstructed.

Motivated by the apparent need for extending the minimal supersymmetric standard model (MSSM) and perhaps mitigating naturalness problems associated with the $\mu$ parameter and fine-tuning of the soft masses, we augment the MSSM spectrum by a SM gauge singlet chiral superfield, and enlarge the gauge structure by an additional $\mathrm{U}(1{)}^{\prime }$ invariance, so that the gauge and Higgs sectors are relatively secluded. One crucial aspect of $\mathrm{U}(1{)}^{\prime }$ models is the existence of anomalies, the cancellation of which may require the inclusion of exotic matter which in turn disrupts the unification of the gauge couplings. In this work we pursue the question of canceling the anomalies with a minimal matter spectrum and no exotics. This can indeed be realized provided that $\mathrm{U}(1{)}^{\prime }$ charges are family dependent and the soft-breaking sector includes nonholomorphic operators for generating the fermion masses. We provide the most general solutions for $\mathrm{U}(1{)}^{\prime }$ charges by taking into account all constraints from gauge invariance and anomaly cancellation. We analyze various laboratory and astrophysical bounds ranging from fermion masses to relic density, for an illustrative set of parameters. The $\mathrm{U}(1{)}^{\prime }$ charges admit patterns of values for which family nonuniversality resides solely in the lepton sector, though this does not generate leptonic flavor-changing neutral currents due to the $\mathrm{U}(1{)}^{\prime }$ gauge invariance.

We calculate the masses of the nucleons and deltas in twisted mass heavy baryon chiral perturbation theory. We work to quadratic order in a power counting scheme in which we treat the lattice spacing, $a$, and the quark masses, $m_q$, to be of the same order. We give expressions for the mass and the mass splitting of the nucleons and deltas both in and away from the isospin limit. We give an argument using the chiral Lagrangian treatment that, in the strong isospin limit, the nucleons remain degenerate and the delta multiplet breaks into two degenerate pairs to all orders in chiral perturbation theory. We show that the mass splitting between the degenerate pairs of the deltas first appears at quadratic order in the lattice spacing. We discuss the subtleties in the effective chiral theory that arise from the inclusion of isospin breaking.

We perform the detailed study of the tetraquark (4Q) potential $V_{4\mathrm{Q}}$ for various $QQ\mathrm{\text{−}}\overline{Q}\overline{Q}$ systems in SU(3) lattice QCD with $\beta =6.0$ and ${16}^3\times 32$ at the quenched level. For about 200 different patterns of 4Q systems, $V_{4\mathrm{Q}}$ is extracted from the 4Q Wilson loop in 300 gauge configurations, with the smearing method to enhance the ground-state component. We calculate $V_{4\mathrm{Q}}$ for planar, twisted, asymmetric, and large-size 4Q configurations, respectively. Here, the calculation for large-size 4Q configurations is done by identifying ${16}^2\times 32$ as the spatial size and 16 as the temporal one, and the long-distance confinement force is particularly analyzed in terms of the flux-tube picture. When $QQ$ and $\overline{Q}\overline{Q}$ are well separated, $V_{4\mathrm{Q}}$ is found to be expressed as the sum of the one-gluon-exchange Coulomb term and multi-Y-type linear term based on the flux-tube picture. When the nearest quark and antiquark pair is spatially close, the system is described as a “two-meson” state. We observe a flux-tube recombination called a “flip-flop” between the connected 4Q state and the two-meson state around the level-crossing point. This leads to infrared screening of the long-range color forces between (anti)quarks belonging to different mesons, and results in the absence of the color van der Waals force between two mesons.

A semiperturbative calculation of the ghost-gluon vertex in Landau-gauge Yang-Mills theory in four and three Euclidean space-time dimensions is presented. Nonperturbative gluon and ghost propagators are employed, which have previously been calculated from a truncated set of Dyson-Schwinger equations and which are in qualitative and quantitative agreement with corresponding lattice results. Our results for the ghost-gluon vertex show only relatively small deviations from the tree-level one in agreement with recent lattice data. In particular, we do not see any sign for a singular behavior of the ghost-gluon vertex in the infrared.

High flux of electron neutrinos(${\nu }_{\mathrm{e}}$) is produced at nuclear power reactors through the decays of nuclei activated by neutron capture. Realistic simulation studies on the neutron transport and capture at the reactor core were performed. The production of ${}^{51}\mathrm{C}\mathrm{r}$ and ${}^{55}\mathrm{F}\mathrm{e}$ give rise to monoenergetic ${\nu }_{\mathrm{e}}$’s at Q-values of 753 keV and 231 keV and fluxes of $8.3\times {10}^{-4}$ and $3.0\times {10}^{-4}{\nu }_{\mathrm{e}}/\mathrm{fission}$, respectively. Using data from a germanium detector at the Kuo-Sheng Power Plant, we derived direct limits on the ${\nu }_{\mathrm{e}}$ magnetic moment and the radiative lifetime of ${\mu }_{\nu }<1.3\times {10}^{-8}{\mu }_{\mathrm{B}}$ and ${\tau }_{\nu }/{\mathrm{m}}_{\nu }>0.11\mathrm{s}/\mathrm{eV}$ at $90\%$ confidence level (CL), respectively. Indirect bounds on ${\tau }_{\nu }/{\mathrm{m}}_{\nu }^3$ were also inferred. The ${\nu }_{\mathrm{e}}$-flux can be enhanced by loading selected isotopes to the reactor core, and the potential applications and achievable statistical accuracies were examined. These include accurate cross-section measurements, studies of mixing angle ${\theta }_{13}$ and monitoring of plutonium production.

We show that the Einstein-aether theory of Jacobson and Mattingly (J&M) can be understood in the framework of the metric-affine (gauge theory of) gravity (MAG). We achieve this by relating the aether vector field of J&M to certain post-Riemannian nonmetricity pieces contained in an independent linear connection of spacetime. Then, for the aether, a corresponding geometrical curvature-square Lagrangian with a massive piece can be formulated straightforwardly. We find an exact spherically symmetric solution of our model.

We consider models of inflation in supergravity with a shift symmetry. We focus on models with one modulus and one inflaton field. The presence of this symmetry guarantees the existence of a flat direction for the inflaton field. Mildly breaking the shift symmetry using a superpotential which depends not only on the modulus, but also on the inflaton field allows one to lift the inflaton flat direction. Along the inflaton direction, the $\eta$ problem is alleviated. Combining the KKLT mechanism for modulus stabilization and a shift symmetry breaking superpotential of the chaotic inflation type, we find models reminiscent of “mutated hybrid inflation” where the inflationary trajectory is curved in the modulus-inflaton plane. We analyze the phenomenology of these models and stress their differences with both chaotic and hybrid inflation.