We present the correlation of low-energy $CP$ phases, both Dirac and Majorana, and the lepton asymmetry for the baryon asymmetry in the universe, with a certain class of Yukawa matrices that consist of two right-handed neutrinos whose mass ratio is about $2\times {10}^{-4}$ and include one texture zero in themselves. For cases in which the amount of the lepton asymmetry $Y_L$ turns out to be proportional to ${\theta }_{13}^2$, we consider the constraint between two types of $CP$ phases and the relation of $Y_L$ versus the Jarlskog invariant or the amplitude of neutrinoless double beta decay as ${\theta }_{13}$ varies.

The top pions (${\Pi }^{0,\pm }$) and the top Higgs ($H_{\mathrm{TC}}$) are the typical particles predicted by the topcolor-assisted technicolor (TC2) model and the observation of these particles can be regarded as the direct evidence of the TC2 model. In this paper, we study two pair production processes of these new particles, i.e., $e^{+}{e}^{-}\to H_{\mathrm{TC}}{\Pi }^0$ and $e^{+}{e}^{-}\to {\Pi }^{+}{\Pi }^{-}$. The results show that the production rates are at the level of several fb for $e^{+}{e}^{-}\to H_{\mathrm{TC}}{\Pi }^0$ and tens of fb for $e^{+}{e}^{-}\to {\Pi }^{+}{\Pi }^{-}$. These processes can produce the adequate distinct multijet final states and the standard model background can be efficiently reduced. So, with the high luminosity at the planned linear colliders, the top pions and top Higgs can be observable via these two pair production processes without question.

The spectral properties of a variety of improved staggered operators are studied in quenched QCD. The systematic dependence of the infrared eigenvalue spectrum on (i) improvement in the staggered operator, (ii) improvement in the gauge field action, (iii) lattice spacing and (iv) lattice volume is analyzed. It is observed that eigenmodes with small eigenvalues and large chirality appear as the level of improvement increases or as one approaches the continuum limit. These eigenmodes can be identified as the “zero modes” which contribute to the chirality associated, via the index theorem, with the topology of the background gauge field. This gives evidence that staggered fermions are sensitive to gauge field topology. After successfully identifying these would-be chiral zero modes, the distribution of the remaining nonchiral modes is compared with the predictions of random matrix theory in different topological sectors. Satisfactory agreement is obtained.

Dürr and Hoelbling recently observed that the continuum and chiral limits do not commute in the two dimensional, one flavor, Schwinger model with staggered fermions. I point out that such lack of commutativity can also be seen in four-dimensional staggered chiral perturbation theory ($\mathrm{S}\chi \mathrm{PT}$) in quenched or partially quenched quantities constructed to be particularly sensitive to the chiral limit. Although the physics involved in the $\mathrm{S}\chi \mathrm{PT}$ examples is quite different from that in the Schwinger model, neither singularity seems to be connected to the trick of taking the ${\mathrm{n}}^{\mathrm{th}}$ root of the fermion determinant to remove unwanted degrees of freedom (“tastes”). Further, I argue that the singularities in $\mathrm{S}\chi \mathrm{PT}$ are absent in standard quantities in the unquenched (full) QCD case and do not imply any unexpected systematic errors in recent MILC calculations with staggered fermions.

The $WW\gamma$ triple gauge boson coupling parameters are studied using $p\overline{p}\to \ell \nu \gamma +X(\ell =e,\mu )$ events at $\sqrt{s}=1.96$ TeV. The data were collected with the D0 detector from an integrated luminosity of $162{\mathrm{pb}}^{-1}$ delivered by the Fermilab Tevatron Collider. The cross section times branching fraction for $p\overline{p}\to W(\gamma )+X\to \ell \nu \gamma +X$ with $E_T^{\gamma }>8$ GeV and $\Delta {\mathcal{R}}_{\ell \gamma }>$ 0.7 is $14.8\pm 1.6(\mathrm{stat})\pm 1.0(\mathrm{syst})\pm 1.0(\mathrm{lum})\mathrm{pb}$. The one-dimensional $95\%$ confidence level limits on anomalous couplings are $-0.88<\Delta {\kappa }_{\gamma }<0.96$ and $-0.20<{\lambda }_{\gamma }<0.20$.

We study the gravitational field of a spinning radiation beam pulse in a higher-dimensional spacetime. We derive first the stress-energy tensor for such a beam in a flat space-time and find the gravitational field generated by it in the linear approximation. We demonstrate that this gravitational field can also be obtained by boosting the Lense-Thirring metric in the limit when the velocity of the boosted source is close to the velocity of light. We then find an exact solution of the Einstein equations describing the gravitational field of a polarized radiation beam pulse in a spacetime with arbitrary number of dimensions. In a $D$-dimensional spacetime this solution contains [$D/2$] arbitrary functions of one variable (retarded time $u$), where [$d$] is the integer part of $d$. For the special case of a four-dimensional spacetime we study effects produced by such a relativistic spinning beam on the motion of test particles and light.

The quantization of gauge-affine gravity within the superfiber bundle formalism is proposed. By introducing an even pseudotensorial 1-superform over a principal superfiber bundle with superconnection, we obtain the geometrical Becchi-Rouet-Stora-Tyutin (BRST) and anti-BRST transformations of the fields occurring in such a theory. Reducing the four-dimensional general affine group double-covering $\overline{GA}(4,\mathbb{R})$ to the Poincaré group double-covering $\overline{ISO}(1,3)$ we also find the BRST and anti-BRST transformations of the fields present in Einstein’s gravity. Furthermore, we give a prescription leading to the construction of both BRST-invariant gauge-fixing action for gauge-affine gravity and Einstein’s gravity.

We show that a microscopic entropy formula based on Virasoro algebra follows from properties of stationary Killing horizons for Lagrangians with arbitrary dependence on Riemann tensor. The properties used are a consequence of regularity of invariants of Riemann tensor on the horizon. Eventual generalization of these results to Lagrangians with derivatives of Riemann tensor, as suggested by an example treated in the paper, relies on assuming regularity of invariants involving derivatives of Riemann tensor. This assumption however leads also to new interesting restrictions on metric functions near the horizon.

We show the $m_{\pi \pi }$ spectrum in $X(3872)\to J/\psi \pi \pi$ can be useful in determination of the $J^{PC}$ quantum number of $X(3872)$.

A numerical solution to the equations of motion for the ekpyrotic bulk brane scenario in the moduli space approximation is presented. The visible universe brane has positive tension, and we use a potential that goes to zero exponentially at large distance, and also goes to zero at small distance. In the case considered, no bulk brane, visible brane collision occurs in the solution. This property and the general behavior of the solution is qualitatively the same when the visible brane tension is negative, and for many different parameter choices.

We study the behavior of spinning strings in the background of various distributions of smeared giant gravitons in supergravity. This gives insights into the behavior of operators of high dimension, spin and $R$ charge. Using a new coordinate system recently presented in the literature, we find that it is particularly natural to prepare backgrounds in which the probe operators develop a variety of interesting new behaviors. Among these are the possession of orbital angular momentum as well as spin, the breakdown of logarithmic scaling of dimension with spin in the high spin regime, and novel splitting/fractionation processes.

We study a supersymmetric model of space-time foam with two stacks each of eight D8-branes with equal string tensions, separated by a single bulk dimension containing D0-brane particles that represent quantum fluctuations. The ground-state configuration with static D-branes has zero vacuum energy, but, when they move, the interactions among the D-branes and D-particles due to the exchanges of strings result in a nontrivial, positive vacuum energy. We calculate its explicit form in the limits of small velocities and large or small separations between the D-branes and/or the D-particles. This nontrivial vacuum energy appears as a central-charge deficit in the noncritical stringy $\sigma$ model describing perturbative string excitations on a moving D-brane. These calculations enable us to characterize the ground state of the D-brane/D-particle system, and provide a framework for discussing brany inflation and the possibility of residual dark energy in the present-day Universe.

We have studied constraints on the equation of state, $w$, and speed of sound, $c_s$, of the dark energy from a joint analysis of data from the cosmic microwave background, large scale structure and type-Ia supernovae. We find that current observations have no significant sensitivity to $c_s$. However, there is a slight difference between models in which there are no dark energy perturbations and models in which dark energy behaves as a fluid. Assuming that there are no dark energy perturbations shifts the allowed region for $w$ to slightly higher values. At present models with and without dark energy perturbations provide roughly equally good fits to observations, but the difference is potentially important for future parameter estimations. Finally, we have also performed error forecasts for future measurements of $c_s$.

We consider the distribution of the non-Gaussian signal induced by weak lensing on the primary total intensity cosmic microwave background (CMB) anisotropies. Our study focuses on the three point statistics exploiting a harmonic analysis based on the CMB bispectrum. By considering the three multipoles as independent variables, we reveal a complex structure of peaks and valleys determined by the reprojection of the primordial acoustic oscillations through the lensing mechanism. We study the dependence of this system on the expansion rate at the epoch in which the weak lensing power injection is relevant, probing the dark energy equation of state at redshift corresponding to the equivalence with matter or higher ($w_{\infty }$). The variation of the latter quantity induces a geometrical feature affecting distances and growth rate of linear perturbations, acting coherently on the whole set of bispectrum coefficients, regardless of the configuration of the three multipoles. We evaluate the impact of the bispectrum observable on the CMB capability of constraining the dark energy dynamics. We perform a maximum likelihood analysis by varying the dark energy abundance, the present equation of state $w_0$ and $w_{\infty }$. We show that the projection degeneracy affecting a pure power spectrum analysis in total intensity is broken if the bispectrum is taken into account. For a Planck-like experiment, assuming nominal performance, no foregrounds or systematics, and fixing all the parameters except $w_0$, $w_{\infty }$ and the dark energy abundance, a percent and ten percent precision measure of $w_0$ and $w_{\infty }$ is achievable from CMB data only. The reason is the enhanced sensitivity of the weak lensing signal to the behavior of the dark energy at high redshifts, which compensates the reduced signal to noise ratio with respect to the primary anisotropies. These results indicate that the detection of the weak lensing signal by the forthcoming CMB probes may be relevant to gain insight into the dark energy dynamics at the onset of cosmic acceleration.

We point out the opportunity of the tau neutrino astronomy for the neutrino energy $E$ ranging between 10 GeV and ${10}^3$ GeV. In this energy range, the intrinsic tau neutrino production is suppressed relative to the intrinsic muon neutrino production. Any sizable tau neutrino flux may thus arise because of the ${\nu }_{\mu }\to {\nu }_{\tau }$ neutrino oscillations only. It is demonstrated that, in the presence of the neutrino oscillations, consideration of the neutrino flavor dependence in the background atmospheric neutrino flux leads to the drastically different prospects between the observation of the astrophysical muon neutrinos and that of the astrophysical tau neutrinos. Taking the galactic-plane neutrino flux as the targeted astrophysical source, we have found that the galactic-plane tau neutrino flux dominates over the atmospheric tau neutrino flux for $E\ge 10\mathrm{GeV}$. Hence, the galactic-plane can at least in principle be seen through the tau neutrinos with energies just greater than 10 GeV. In a sharp contrast, the galactic-plane muon neutrino flux is overwhelmed by its atmospheric background until $E\ge {10}^6$ GeV.

We study spherically symmetric black hole solutions with Skyrme hair in the Einstein-Skyrme theory with a negative cosmological constant. The dependence of the Skyrmion field configuration on the cosmological constant is examined. The stability is investigated in detail by solving the linearly perturbed equation numerically. It is shown that there exist linearly stable solutions in the branch which represents unstable configuration in the asymptotically flat spacetime.

We study even parity metric and matter perturbations of all angular modes in self-similar Vaidya space-time. We focus on the case where the background contains a naked singularity. Initial conditions are imposed, describing a finite perturbation emerging from the portion of flat space-time preceding the matter-filled region of space-time. The most general perturbation satisfying the initial conditions is allowed to impinge upon the Cauchy horizon (CH), where the perturbation remains finite: There is no “blue-sheet” instability. However, when the perturbation evolves through the CH and onto the second future similarity horizon of the naked singularity, divergence necessarily occurs: This surface is found to be unstable. The analysis is based on the study of individual modes following a Mellin transform of the perturbation. We present an argument that the full perturbation remains finite after resummation of the (possibly infinite number of) modes.

The thermodynamics of black holes is shown to be directly induced by their near-horizon conformal invariance. This behavior is exhibited using a scalar field as a probe of the black hole gravitational background, for a general class of metrics in $D$ spacetime dimensions (with $D\ge 4$). The ensuing analysis is based on conformal quantum mechanics, within a hierarchical near-horizon expansion. In particular, the leading conformal behavior provides the correct quantum statistical properties for the Bekenstein-Hawking entropy, with the near-horizon physics governing the thermodynamics from the outset. Most importantly: (i) this treatment reveals the emergence of holographic properties; (ii) the conformal coupling parameter is shown to be related to the Hawking temperature; and (iii) Schwarzschild-like coordinates, despite their “coordinate singularity,” can be used self-consistently to describe the thermodynamics of black holes.

We clarify inflaton models by considering them as effective field theories in the Ginzburg-Landau spirit. In this new approach, the precise form of the inflationary potential is constructed from the present WMAP data, and a useful scheme is prepared to confront with the forthcoming data. In this approach, the WMAP statement excluding the pure ${\varphi }^4$ potential implies the presence of an inflaton mass term at the scale $m\sim {10}^{13}\mathrm{GeV}$. Chaotic, new and hybrid inflation models are studied in an unified way. In all cases the inflaton potential takes the form $V(\varphi )=m^2{M}_{\mathrm{Pl}}^{2}v(\varphi /M_{\mathrm{Pl}})$, where all coefficients in the polynomial $v(\phi )$ are of order one. If such potential corresponds to supersymmetry breaking, the corresponding susy breaking scale is $\sqrt{m{M}_{\mathrm{Pl}}}\sim {10}^{16}\mathrm{GeV}$ which turns to coincide with the grand unification (GUT) scale. The inflaton mass is therefore given by a seesaw formula $m\sim M_{\mathrm{GUT}}^2/M_{\mathrm{Pl}}$. The observables turn to be two-valued functions: one branch corresponds to new inflation and the other to chaotic inflation, the branch point being the pure quadratic potential. For red tilted spectrum, the potential which fits the best the present data ($|1-n_s|\lesssim 0.1,r\lesssim 0.1$) and which best prepares the way for the forthcoming data is a trinomial polynomial with negative quadratic term (new inflation). For blue tilted spectrum, hybrid inflation turns to be the best choice. In both cases we find an analytic formula relating the inflaton mass with the ratio $r$ of tensor to scalar perturbations and the spectral index $n_s$ of scalar perturbations: ${10}^6(m/M_{\mathrm{Pl}})=127\sqrt{r|1-n_s|}$ where the numerical coefficient is fixed by the WMAP amplitude of adiabatic perturbations. Implications for string theory are discussed.

We discuss the threshold anomaly in ultrahigh energy cosmic ray physics by assuming that the matter world just be a perturbation of a de Sitter universe, which is consistent with the recent astronomical observations: about two-thirds of the whole energy in the Universe is contributed by a small positive cosmological constant. One-particle states are presented explicitly. It is noticed that the dispersion relation of free particles is dependent on the degrees of freedom of angular momentum. This fact can be regarded as the effects of the cosmological constant on kinematics of particles.