We present results for excited meson spectra from $N_f=2$ clover-Wilson configurations provided by the CP-PACS Collaboration. In our study we investigate both low and high spin mesons. For spin-0 and spin-1 mesons, we are especially interested in the excited states. To access these states we construct several different interpolators from quark sources of different spatial smearings and calculate a matrix of correlators. For this matrix we then solve a generalized eigenvalue problem. For spin-2 and spin-3, we extract only the lowest lying states.

In this paper, we first calculate the realistic Earth matter effects in the detection of type II supernova neutrinos at the Daya Bay reactor neutrino experiment which is currently under construction. It is found that the Earth matter effects depend on the neutrino incident angle $\theta$, the neutrino mass hierarchy $\Delta m_{31}^2$, the crossing probability at the high resonance region inside the supernova, $P_H$, the neutrino temperature, $T_{\alpha }$, and the pinching parameter in the neutrino spectrum, ${\eta }_{\alpha }$. We also take into account the collective effects due to neutrino-neutrino interactions inside the supernova. With the expression for the dependence of $P_H$ on the neutrino mixing-angle ${\theta }_{13}$, we obtain the relations between ${\theta }_{13}$ and the event numbers for various reaction channels of supernova neutrinos. Using these relations, we propose a possible method to acquire information about ${\theta }_{13}$ smaller than 1.5°. Such a sensitivity cannot be achieved by the reactor neutrino deta at the Daya Bay experiment which has a sensitivity of the order of ${\theta }_{13}\sim 3°$. Furthermore, we apply this method to other neutrino experiments, i.e. Super-K, SNO, KamLAND, LVD, MinBooNE, Borexino, and Double-Chooz. We also study the energy spectra of the differential event numbers, $dN/dE$.

We perform an exploratory study of the allowed parameter range for the CKM-like mixing of hypothetical quarks of a fourth generation. As experimental constraints we use the tree-level determinations of the $3\times 3$ Cabibbo-Kobayashi-Maskawa (CKM) elements and flavor-changing neutral current (FCNC) processes ($K$, $D$, $B_d$, $B_s$ mixing and the decay $b\to s\gamma$) under the assumption that the $4\times 4$ CKM matrix is unitary. For the FCNCs we use some simplifying assumptions concerning the QCD corrections. Typically small mixing with the fourth family is favored; contrary to expectation, however, we find that also a quite large mixing with the fourth family is not yet excluded.

We use big bang nucleosynthesis bounds on the variation of the gravitational coupling to derive constraints on the strength of the deviation from the gravitational inverse-square law due to tensor and vector unparticle exchange.

Recently, a state of the art experiment shows evidence for Lorentz violation in the gravitational sector. To explain this experiment, we investigate a spontaneous Lorentz violation scenario with a generalized scalar field. We find that when the scalar field is nonminimally coupled to gravity, the Lorentz violation induces a deformation in the Newtonian potential along the direction of Lorentz violation.

We compute the penetration depth of a light quark moving through a large $N_{\mathrm{c}}$, strongly coupled $\mathcal{N}=4$ supersymmetric Yang-Mills plasma using gauge/gravity duality and a combination of analytic and numerical techniques. We find that the maximum distance a quark with energy $E$ can travel through a plasma is given by $\Delta x_{\max }(E)=(\mathcal{C}/T)(E/T\sqrt{\lambda }{)}^{1/3}$ with $\mathcal{C}\approx 0.5$.

We calibrate the effective-one-body (EOB) model to an accurate numerical simulation of an equal-mass, nonspinning binary black-hole coalescence produced by the Caltech-Cornell Collaboration. Aligning the EOB and numerical waveforms at low frequency over a time interval of $\sim 1000M$, and taking into account the uncertainties in the numerical simulation, we investigate the significance and degeneracy of the EOB-adjustable parameters during inspiral, plunge, and merger, and determine the minimum number of EOB-adjustable parameters that achieves phase and amplitude agreements on the order of the numerical error. We find that phase and fractional amplitude differences between the numerical and EOB values of the dominant gravitational-wave mode $h_{22}$ can be reduced to 0.02 radians and 2%, respectively, until a time $20M$ before merger, and to 0.04 radians and 7%, respectively, at a time $20M$ after merger (during ringdown). Using LIGO, Enhanced LIGO, and Advanced LIGO noise curves, we find that the overlap between the EOB and the numerical $h_{22}$, maximized only over the initial phase and time of arrival, is larger than 0.999 for equal-mass binary black holes with total mass $30–150M_{\odot }$. In addition to the leading gravitational mode (2, 2), we compare the dominant subleading modes (4, 4) and (3, 2) for the inspiral and find phase and amplitude differences on the order of the numerical error. We also determine the mass-ratio dependence of one of the EOB-adjustable parameters by calibrating to numerical inspiral waveforms for black-hole binaries with mass ratios $2:1$ and $3:1$. The results presented in this paper improve and extend recent successful attempts aimed at providing gravitational-wave data analysts the best analytical EOB model capable of interpolating accurate numerical simulations.

We compute the contribution to the Lagrangian from the leading order (2.5 post-Newtonian) radiation reaction and the quadrupolar gravitational waves emitted from a binary system using the effective field theory (EFT) approach of Goldberger and Rothstein. We use an initial value formulation of the underlying (quantum) framework to implement retarded boundary conditions and describe these real-time dissipative processes. We also demonstrate why the usual scattering formalism of quantum field theory inadequately accounts for these. The methods discussed here should be useful for deriving real-time quantities (including radiation reaction forces and gravitational wave emission) and hereditary terms in the post-Newtonian approximation (including memory, tail and other causal, history-dependent integrals) within the EFT approach. We also provide a consistent formulation of the radiation sector in the equivalent effective field theory approach of Kol and Smolkin.

We have studied the perturbation of a spinning dilaton black hole in $2+1$ dimensions by a massless scalar field. The wave equations of a massless scalar field is shown to be exactly solvable in terms of hypergeometric functions. The quasinormal frequencies are computed for slowly spinning black holes. The stability of the black hole is discussed. The asymptotic form of the quasinormal frequencies are evaluated. The area spectrum of the quantum black holes are evaluated by using the asymptotic quasinormal frequencies and is shown to be equally spaced.

We investigate the feasibility of explosive particle production via parametric resonance or tachyonic preheating in multifield inflationary models by means of lattice simulations. We observe a strong suppression of resonances in the presence of four-leg interactions between the inflaton fields and a scalar matter field, leading to insufficient preheating when more than two inflatons couple to the same matter field. This suppression is caused by a dephasing of the inflatons that increases the effective mass of the matter field. Including three-leg interactions leads to tachyonic preheating, which is not suppressed by an increase in the number of fields. If four-leg interactions are subdominant, we observe a slight enhancement of tachyonic preheating. Thus, in order for preheating after multifield inflation to be efficient, one needs to ensure that three-leg interactions are present. If no tachyonic contributions exist, we expect the old theory of reheating to be applicable.

We consider the quantization of a Friedmann-Robertson-Walker universe. We derive a reduced square root Hamiltonian by choosing the scale factor as time variable and quantize the theory using Pauli matrices à la Dirac. From the resulting spinor equation we show that there is no semiclassical wave packet that avoids the big bang singularity. Our work raises the question concerning the relationship between the choice of time and singularity avoidance.

We consider the asymptotically flat double-Kerr solution for two equal mass black holes with either the same or opposite angular momentum and with a massless strut between them. For fixed angular momentum and mass, the angular velocity of two corotating Kerr black holes decreases as they approach one another, from the Kerr value at infinite separation to the value of a single Kerr black hole with twice the mass and the angular momentum at the horizons merging limit. We show that the ratio $J/M^2$ for extremal corotating Kerr black holes varies from unity at infinite separation to two at the merging limit. These results are interpreted in terms of rotational dragging and compared with the case of counterrotating Kerr black holes. We then analyze the merging of ergoregions. In the corotating case the merger point occurs at an angle of $\pi /2$, in agreement with recent general arguments. In the counterrotating case the ergoregions never merge. We study the horizon geometry for both cases as a function of the distance and provide embedding diagrams. Finally, we study the thermodynamical evolution of the corotating double-Kerr system, showing that, in the canonical ensemble, it is thermodynamically stable for fast spinning black holes. As for single Kerr black holes the stable and unstable phases are separated by a second order phase transition. We show that for large fixed angular momentum two Kerr black holes reach a minimum distance, before horizon merging has occurred, where the thermodynamical approximation breaks down. We also consider the microcanonical ensemble to study the maximal energy that can be extracted from the double-Kerr system as a function of the separation between the black holes.

Following Kamionkowski (2008), a quadratic estimator of the rotation of the plane of polarization of the cosmic microwave background (CMB) is constructed. This statistic can estimate a spatially varying rotation angle $\alpha (n)$. We use this estimator to quantify the prospects of detecting such a rotation field with forthcoming experiments. For PLANCK and CMBPol experiments, we find that the estimator containing the product of the $E$ and $B$ components of the polarization field is the most sensitive. The variance of this $EB$ estimator $N(L)$ is roughly independent of the multipole $L$ and is only weakly dependent on the instrumental beam. For FWHM of the beam size ${\Theta }_{\mathrm{fwhm}}\sim 5^{\prime }–{50}^{\prime }$ and instrument noise ${\Delta }_p\sim 5–50\mu \mathrm{K}\mathrm{\text{−}}\mathrm{arcmin}$, the scaling of variance $N(L)$ can be fitted by a power law $N(L)=3.3\times {10}^{-7}{\Delta }_p^2{\Theta }_{\mathrm{fwhm}}^{1.3}{deg}^2$. For small instrumental noise ${\Delta }_p\le 5\mu \mathrm{K}\mathrm{\text{−}}\mathrm{arcmin}$, the lensing $B$ modes become important, saturating the variance to $\sim {10}^{-6}{deg}^2$ even for an ideal experiment. Upcoming experiments like PLANCK will be able to detect a power spectrum of the rotation angle, $C^{\alpha \alpha }(L)$, as small as $0.01{deg}^2$, while futuristic experiments like CMBPol will be able to detect rotation angle power spectrum as small as $2.5\times {10}^{-5}{deg}^2$. We discuss the implications of such constraints, both for the various physical effects that can rotate the polarization as photons travel from the last scattering surface as well as for constraints on instrumental systematics that can also lead to a spurious rotation signal. Rotation of the CMB polarization generates $B$ modes which will act as contamination for the primordial $B$-mode detection. We discuss an application of our estimator to derotate the CMB to increase the sensitivity for the primordial $B$ modes.

The dressed-electron eigenstate of Feynman-gauge QED is computed in light-front quantization with a Fock-space truncation to include at most the one-photon/one-electron sector. The theory is regulated by the inclusion of three massive Pauli-Villars (PV) particles, one PV electron, and two PV photons. In particular, the chiral-limit is investigated, and the correct limit is found to require two PV photons, not just one as previously thought. The renormalization and covariance of the electron current are also analyzed. We find that the plus component is well behaved and use its spin-flip matrix element to compute the electron’s anomalous moment. The dependence of the moment on the regulator masses is shown to be slowly varying when the second PV photon is used to guarantee the correct chiral limit.

Since gravitational wave spacetimes are time-varying vacuum solutions of Einstein’s field equations, there is no unambiguous means to define their energy content. However, Weber and Wheeler had demonstrated that they do impart energy to test particles. There have been various proposals to define the energy content, but they have not met with great success. Here we propose a definition using “slightly broken” Noether symmetries. We check whether this definition is physically acceptable. The procedure adopted is to appeal to “approximate symmetries” as defined in Lie analysis and use them in the limit of the exact symmetry holding. A problem is noted with the use of the proposal for plane-fronted gravitational waves. To attain a better understanding of the implications of this proposal we also use an artificially constructed time-varying nonvacuum metric and evaluate its Weyl and stress-energy tensors so as to obtain the gravitational and matter components separately and compare them with the energy content obtained by our proposal. The procedure is also used for cylindrical gravitational wave solutions. The usefulness of the definition is demonstrated by the fact that it leads to a result on whether gravitational waves suffer self-damping.

We discuss chiral symmetry breaking in the intersecting brane model of Sakai and Sugimoto at weak coupling for a generic value of separation $L$ between the flavor $D8$ and anti-$D8$-branes. For any finite value of the radius $R$ of the circle around which the color $D4$-branes wrap, a nonlocal Nambu–Jona-Lasinio-type short-range interaction couples the flavor branes and antibranes. We argue that chiral symmetry is broken in this model only above a certain critical value of the four-dimensional ’t Hooft coupling and confirm this through numerical calculations of solutions to the gap equation. We also numerically investigate chiral symmetry breaking in the limit $R\to \infty$ keeping $L$ fixed, but find that simple ways of implementing this limit do not lead to a consistent picture of chiral symmetry breaking in the noncompact version of the nonlocal Nambu–Jona-Lasinio model.

The motion of massive point matter in area metric spacetimes, which arise as refinements of the Lorentzian spacetime structure in various situations of physical interest, is shown to be governed by a Finslerian geometry. This finding is based on the study of interacting string fluids on area metric manifolds, and extends previous findings on the motion of light rays.

We consider the behavior of massive Dirac fields on the background of a charged de Sitter black hole. All black hole geometries are taken into account, including the Reissner-Nordström-de Sitter one, the Nariai case, and the ultracold case. Our focus is at first on the existence of bound quantum mechanical states for the Dirac Hamiltonian on the given backgrounds. In this respect, we show that in all cases no bound state is allowed, which amounts also to the nonexistence of normalizable time-periodic solutions of the Dirac equation. This quantum result is in contrast to classical physics, and it is shown to hold true even for extremal cases. Furthermore, we shift our attention on the very interesting problem of the quantum discharge of the black holes. Following the Damour-Deruelle-Ruffini approach, we show that the existence of level crossing between positive and negative continuous energy states is a signal of the quantum instability leading to the discharge of the black hole, and in the cases of the Nariai geometry and of the ultracold geometries we also calculate in WKB approximation the transmission coefficient related to the discharge process.

In this paper we examine the derivation of scale-dependent bias due to primordial non-Gaussianity of the local type in the context of general relativity. We justify the use of the Poisson equation in general relativistic perturbation theory and thus the derivation of scale-dependent bias as a test of primordial non-Gaussianity, using the spherical collapse model. The corollary is that the form of scale-dependent bias does not receive general relativistic corrections on scales larger than the Hubble radius. This leads to a formally divergent correlation function for biased tracers of the mass distribution which we discuss.

We study a neutron star with a quark matter core under extremely strong magnetic fields. We investigate the possibility of an Urca process as a mechanism for the cooling of such a star. We found that apart from very particular cases, the Urca process cannot occur. We also study the stability of zero sound modes under the same conditions. We derive limits for the coupling constant of an effective theory, in order the zero sound to be undamped. We show that zero sound modes can help kinematically to facilitate a cooling process. Our conclusions hold for unpaired quark matter and not superconducting.