We study the late-time tails appearing in the propagation of massless fields (scalar, electromagnetic, and gravitational) in the vicinities of a D-dimensional Schwarzschild black hole. We find that at late times the fields always exhibit a power-law falloff, but the power law is highly sensitive to the dimensionality of the spacetime. Accordingly, for odd $D>\mathrm{}3\mathrm{}$ we find that the field behaves as $t^{-(2l+D-2)}$ at late times, where l is the angular index determining the angular dependence of the field. This behavior is entirely due to D being odd; it does not depend on the presence of a black hole in the spacetime. Indeed this tail is already present in the flat space Green’s function. On the other hand, for even $D>\mathrm{}4\mathrm{}$ the field decays as $t^{-(2l+3D-8)},$ and this time there is no contribution from the flat background. This power law is entirely due to the presence of the black hole. The $D=4\mathrm{}$ case is special and exhibits, as is well known, $t^{-\mathrm{}(2l+3)\mathrm{}}$ behavior. In the extra dimensional scenario for our Universe, our results are strictly correct if the extra dimensions are infinite, but also give a good description of the late-time behavior of any field if the large extra dimensions are large enough.

We study the optical paths of the light rays propagating inside a nonlinear moving dielectric medium. For rapidly moving dielectrics we show the existence of a distinguished surface which resembles, as far as the light propagation is concerned, the event horizon of a black hole. Our analysis clarifies the physical conditions under which electromagnetic analogues of gravitational black holes can eventually be obtained in laboratory.

We argue that the demand of background independence in a quantum theory of gravity calls for an extension of standard geometric quantum mechanics. We discuss a possible kinematical and dynamical generalization of the latter by way of a quantum covariance of the state space. Specifically, we apply our scheme to the problem of a background independent formulation of matrix theory.

The laser interferometer space antenna is an array of three spacecraft in an approximately equilateral triangle configuration which will be used as a low-frequency gravitational wave detector. We present here new generalizations of the Michelson- and Sagnac-type time-delay interferometry data combinations. These combinations cancel laser phase noise in the presence of different up and down propagation delays in each arm of the array, and slowly varying systematic motion of the spacecraft. The gravitational wave sensitivities of these generalized combinations are the same as previously computed for the stationary cases, although the combinations are now more complicated. We introduce a diagrammatic representation to illustrate that these combinations are actually synthesized equal-arm interferometers.

For nonuniversal gaugino masses, collider experiments do not provide any lower bound on the mass of the lightest neutralino. We review the supersymmetric parameter space which leads to light neutralinos, $M_{\tilde{\chi }}\lesssim O\left(1\mathrm{}\mathrm{GeV}\right),$ and find that such neutralinos are almost pure bino. In light of this, we examine the neutralino lower mass bound obtained from supernova 1987A (SN 1987A). We consider the production of binos in both electron-positron annihilation and nucleon-nucleon binostrahlung. For electron-positron annihilation, we take into account the radial and temporal dependence of the temperature and degeneracy of the supernova core. We also separately consider the Raffelt criterion and show that the two lead to consistent results. For the case of bino production in nucleon-nucleon collisions, we use the Raffelt criterion and incorporate recent advances in the understanding of the strong-interaction part of the calculation in order to estimate the impact of bino radiation on the SN 1987A neutrino signal. Considering these two bino production channels allows us to determine separate and combined limits on the neutralino mass as a function of the selectron and squark masses. For $M_{\tilde{\chi }}\sim 100\mathrm{MeV}$ values of the selectron mass between 300 and 900 GeV are inconsistent with the supernova neutrino signal. On the other hand, in contrast to previous works, we find that SN 1987A provides almost no bound on the squark masses: only a small window of values around 300 GeV can be excluded and even then this window closes once $M_{\tilde{\chi }}\gtrsim 20\mathrm{MeV}.$

We derive the quark mass dependence of $m_{\pi }^2,$ $m_{\mathrm{AWI}},$ and $f_{\pi },$ using chiral perturbation theory, which includes the $a^2$ effect associated with the explicit chiral symmetry breaking of the Wilson-type fermions, in the case of the $N_f=2\mathrm{}$ degenerate quarks. The distinct features of the results are (1) the additive renormalization for the mass parameter $m_q$ in the Lagrangian, (2) $O\left(a\right)\mathrm{}$ corrections to the chiral log ${(m}_q\log m_q)$ term, (3) the existence of a more singular term $\log m_q$ generated by $a^2$ contributions, and (4) the existence of both $m_q\log m_q$ and $\log m_q$ terms in the quark mass from the axial Ward-Takahashi identity $m_{\mathrm{AWI}}.$ By fitting the mass dependence of $m_{\pi }^2$ and $m_{\mathrm{AWI}},$ obtained by the CP-PACS Collaboration for $N_f=2\mathrm{}$ full QCD simulations, we find that the data are consistently described by the derived formulas. Resumming the most singular terms $\log m_q,$ we also derive modified formulas, which show a better control over the next-to-leading order correction.

We examine the spectrum of two-color lattice QCD with one staggered quark field (four flavors) at a finite chemical potential $\left(\mu \right)$ for quark number, on a ${12}^3\times 24$ lattice. First we present evidence that the system undergoes a transition to a state with a diquark condensate, which spontaneously breaks quark number at $\mu {=m}_{\pi }/2,$ and that this transition is mean field in nature. We then examine the three states that would be Goldstone bosons at $\mu =0\mathrm{}$ for zero Dirac and Majorana quark masses. The predictions of chiral effective Lagrangians give a good description of the behavior of these masses for $\mu <m_{\pi }/2.\mathrm{}$ Except for the heaviest of these states, these predictions diverge from our measurements, once $\mu$ is significantly greater than $m_{\pi }/2.\mathrm{}$ However, the qualitative behavior of these masses indicates that the physics is very similar to that predicted by these effective Lagrangians, and there is some indication that at least part of these discrepancies is due to saturation, a lattice artifact.

We present the first results for masses of spin-$\frac{3}{2}$ N and $\Delta$ baryons in lattice QCD using fat-link irrelevant clover fermions. Spin-$\frac{3}{2}$ interpolating fields, providing overlap with both spin-$\frac{3}{2}$ and spin-$\frac{1}{2}$ states, are considered. In the isospin-$\frac{1}{2}$ sector we observe, after appropriate spin and parity projection, a strong signal for the $J^P={\frac{3}{2}}^{-}$ state together with a weak but discernible signal for the ${\frac{3}{2}}^{+}$ state with a mass splitting near that observed experimentally. We also find good agreement between the ${\frac{1}{2}}^{\pm }$ masses and earlier nucleon mass simulations with the standard spin-$\frac{1}{2}$ interpolating field. For the isospin-$\frac{3}{2}$ $\Delta$ states, clear mass splittings are observed between the various ${\frac{1}{2}}^{\pm }$ and ${\frac{3}{2}}^{\pm }$ channels, with the calculated level orderings in good agreement with those observed empirically.

We discuss the possibility of a large electroweak penguin contribution in $\overrightarrow{B}K\pi$ from recent experimental data. The several relations among the branching ratios which realize when the contributions from tree type and electroweak penguin contributions are small compared with the gluon penguin can be treated as the expansion parameters do not satisfy the data. The difference comes from the $r^2$ term which is the square of the ratio with the gluon penguin diagram and the main contribution comes from the electroweak penguin diagram. We find that the electroweak penguin contribution may be too large to explain the experimental data. If the magnitude estimated from experiment is quite large compared with the theoretical estimation, then it may be including some new physics effects.

We demonstrate the equivalence of the relativistic flux tube model of mesons to a simple potential model in the regime of large radial excitation. We make no restriction on the quark masses; either quark may have a zero or finite mass. Our primary result shows that for fixed angular momentum and large radial excitation, the flux tube or QCD string meson with a short-range Coulomb interaction is described by a spinless Salpeter equation with a time component vector potential $V\left(r\right)=ar-k/r.\mathrm{}$

We calculate the expectation values of QCD operators consisting of the products of the four operators of the light quarks $\overline{q}{\Gamma }^{X}q\overline{q}{\Gamma }^{Y}q,$ with ${\Gamma }^{X,Y}$ corresponding to the scalar, pseudoscalar, vector, pseudovector (axial), and tensor Lorentz structures, in the nucleon. All combinations of the light flavors are considered. For the evaluation we use elements of the perturbative chiral quark model (PCQM), approximating the contribution of the valence quarks by the contribution of the PCQM constituent quarks. The contribution of the sea quarks is treated by averaging over the QCD pions with the distribution of the pion field being determined by the PCQM. For quarks with the same flavor the expectation values are dominated by the contribution of the sea quarks. In the scalar case the contribution of the sea quarks is dominated by the “disconnected terms” where one of the pairs of the $\overline{q}q$ operators acts on the vacuum while the other one acts on the quarks of the pion. The role of the interference terms with one of the $\overline{q}q$ pairs acting on the sea quarks and the other one acting on the valence quarks increases for quarks with different flavors. The result for the scalar condensate is compared to that obtained earlier in the framework of the Nambu–Jona-Lasinio model.

We study weak interactions involving Goldstone bosons in the neutral kaon condensed phase of color flavor locked quark matter. We calculate the rates for the dominant processes that contribute to the neutrino mean free path and to neutrino production. A light $K^{+}$ state, with a mass $m_{K^{+}}\propto (\Delta /\mu )\left(\Delta {/m}_s{\left)\right(m}_d-m_u\right),$ where $\mu$ and $\Delta$ are the quark chemical potential and superconducting gap respectively, is shown to play an important role. We identify unique characteristics of weak interaction rates in this novel phase and discuss how they might influence neutrino emission in core collapse supernova and neutron stars.

The atmospheric secondary proton flux is studied for altitudes extending from sea level up to the top of the atmosphere by means of a three-dimensional Monte Carlo simulation procedure successfully used previously to account for flux measurements of protons, light nuclei, and electron-positron pairs below the geomagnetic cutoff (satellite data), and of muons and antiprotons (balloon data). The calculated fluxes are compared with the experimental measurements from sea level up to high float balloon altitudes. The agreement between data and simulation results is very good at all altitudes, including the lowest ones, where the calculations become extremely sensitive to the proton production cross section. The results are discussed in this context. The calculations are extended to the study of quasitrapped particles above the atmosphere to about five earth radii, for prospective purpose.

The atmospheric secondary antiproton flux is studied for detection altitudes extending from sea level up to about three earth radii, by means of a three-dimensional Monte Carlo simulation, successfully applied previously to other satellite and balloon data. The calculated antiproton flux at mountain altitude is found to be in fair agreement with the recent BESS measurements. The flux obtained at balloon altitude is also in agreement with calculations performed in previous studies and used for the analysis of balloon data. The flux at sea level is found to be significant. The antineutron flux is also evaluated. The antiproton flux is prospectively explored up to around $2\times {10}^4\mathrm{km}$ from the Earth. The results are discussed in the context of the forthcoming measurements by large acceptance experiments.

Precise knowledge of the mass composition of the primary cosmic ray flux below and above the knee in the primary energy spectrum at $E\sim 3\times {10}^{15}$ eV is essential for understanding the acceleration and propagation of high energy cosmic rays. Simulations have shown that the correlations between the electron and muon components of showers are very sensitive to the mass of the primary nuclei. In particular, different regions of the muon multiplicity distribution observed with a large area muon detector, for well-defined selection on the electron component of showers, have a high sensitivity to different nuclear groups present in the primary flux. The GRAPES-2 experiment at Ooty seeks to exploit this sensitivity using a $200{\mathrm{m}}^2$ area muon detector to study the mass composition of the primary flux in the energy range ${10}^{14}–{10}^{16}$ eV. The details of the experiment are presented and early observations are discussed in relation to the expectations from simulations.

A search for narrow-width resonances that decay into electron+jet or neutrino+jet has been performed with the ZEUS detector at the DESY $\mathrm{ep}$ collider HERA operating at center-of-mass energies of 300 and 318 GeV. An integrated $e^{+}p$ luminosity of $114.8{\mathrm{pb}}^{-1}$ and $e^{-}p$ luminosity of $16.7{\mathrm{pb}}^{-1}$ were used. No evidence for any resonance was found. Limits were derived on the Yukawa coupling $\lambda$ as a function of the mass of a hypothetical resonance that has arbitrary decay branching ratios into $\mathrm{eq}$ or $\nu q.\mathrm{}$ These limits also apply to squarks predicted by R-parity-violating supersymmetry. Limits for the production of leptoquarks described by the Buchmüller-Rückl-Wyler model were also derived for masses up to 400 GeV. For $\lambda =0.1,$ leptoquark masses up to 290 GeV are excluded.

Motivated by the Randall-Sundrum braneworld scenario, we discuss the classical and quantum dynamics of a $\mathrm{}(d+1\mathrm{})\mathrm{}$-dimensional boundary wall between a pair of $\mathrm{}(d+2\mathrm{})\mathrm{}$-dimensional topological Schwarzschild-AdS black holes. We assume there are quite general—but not completely arbitrary—matter fields living on the boundary “brane universe,” and that its geometry is that of a Friedmann-Lemaître-Robertson-Walker (FLRW) model. The effective action governing the model in the minisuperspace approximation is derived. We find that the presence of black hole horizons in the bulk gives rise to a complex action for certain classically allowed brane configurations, but that the imaginary contribution plays no role in the equations of motion. Classical and instanton brane trajectories are examined in general and for special cases, and we find a subset of configuration space that is not allowed at the classical or semiclassical level; this subset corresponds to spacelike branes carrying tachyonic matter. The Hamiltonization and Dirac quantization of the model is then performed for the general case; the latter involves the manipulation of the Hamiltonian constraint before it is transformed into an operator that annihilates physical state vectors. The ensuing covariant Wheeler-DeWitt equation is examined at the semiclassical level, and we consider the possible localization of the brane universe’s wave function away from the cosmological singularity. This is easier to achieve for branes with low density and/or spherical spatial sections.

The tachyon effective field theory describing the dynamics of a non-Bogomol’nyi-Prasad-Sommerfield (BPS) D-brane in superstring theory has an infinitely thin but finite tension kink solution describing a codimension one BPS D-brane. We study the world-volume theory of massless modes on the kink, and show that the world volume action has precisely the Dirac-Born-Infeld (DBI) form without any higher derivative corrections. We generalize this to a vortex solution in the effective field theory on a brane-antibrane pair. As in the case of the kink, the vortex is infinitely thin, has finite energy density, and the world-volume action on the vortex is again given exactly by the DBI action on a BPS D-brane. We also discuss the coupling of fermions and restoration of supersymmetry and $\kappa$ symmetry on the world volume of the kink. The absence of higher derivative corrections to the DBI action on the soliton implies that all such corrections are related to higher derivative corrections to the original effective action on the world volume of a non-BPS D-brane or brane-antibrane pair.

The Ginsparg-Wilson algebra is the algebra underlying the Ginsparg-Wilson solution of the fermion doubling problem in lattice gauge theory. The Dirac operator of the fuzzy sphere is not afflicted with this problem. Previously, we have indicated that there is a Ginsparg-Wilson operator underlying it also in the absence of gauge fields and instantons. Here we develop this observation systematically and establish a Dirac operator theory for the fuzzy sphere with or without gauge fields, and always with the Ginsparg-Wilson algebra. There is no fermion doubling in this theory. The association of the Ginsparg-Wilson algebra with the fuzzy sphere is surprising as the latter is not designed with this algebra in mind. The theory reproduces the integrated ${U\left(1\right)\mathrm{}}_A$ anomaly and index theory correctly.

We study the Hamiltonian structure of the gauge symmetry enhancement in the enlarged $\mathrm{CP}\mathrm{}\left(N\right)\mathrm{}$ model coupled with a $U\left(2\right)\mathrm{}$ Chern-Simons term, which contains a free parameter governing explicit symmetry breaking and symmetry enhancement. After giving a general discussion of the geometry of constrained phase space suitable for the enhancement, we explicitly perform the Dirac analysis of our model and compute the Dirac brackets for the symmetry enhanced and broken cases. We also discuss some related issues.