Using data collected by the CLEO III detector at CESR, we report on the first observation of the decays ${\Lambda }_c^{+}\to \Lambda {\pi }^{+}{\pi }^{+}{\pi }^{-}{\pi }^0$ and ${\Lambda }_c^{+}\to \Lambda \omega {\pi }^{+}.$ The branching fractions are measured relative to the ${\mathrm{pK}}^{-}{\pi }^{+}$ mode; we find $\mathcal{B}({\Lambda }_c^{+}\to \Lambda {\pi }^{+}{\pi }^{+}{\pi }^{-}{\pi }^0)/\mathcal{B}({\Lambda }_c^{+}\to {\mathrm{pK}}^{-}{\pi }^{+})=0.36\mathrm{}\pm 0.09\left(\mathrm{stat}\right)\pm 0.09\left(\mathrm{syst}\right)$ and $\mathcal{B}({\Lambda }_c^{+}\to \Lambda \omega {\pi }^{+})/\mathcal{B}({\Lambda }_c^{+}\to {\mathrm{pK}}^{-}{\pi }^{+})=0.24\mathrm{}\pm 0.06\left(\mathrm{stat}\right)\pm 0.06\left(\mathrm{syst}\right).\mathrm{}$ We also observe a small excess of events in ${\Lambda }_c^{+}\to \Lambda \eta {\pi }^{+},$ $\overrightarrow{\eta }{\pi }^{+}{\pi }^{-}{\pi }^0$ from which we find $\mathcal{B}({\Lambda }_c^{+}\to \Lambda \eta {\pi }^{+})/\mathcal{B}({\Lambda }_c^{+}\to {\mathrm{pK}}^{-}{\pi }^{+})=0.41\mathrm{}\pm 0.17\pm 0.10$ with a corresponding limit of $<0.65\%$ at 90% confidence level. This rate is consistent with previous measurements of ${\Lambda }_c^{+}\to \Lambda \eta {\pi }^{+},$ $\overrightarrow{\eta }\gamma \gamma .$ We find that the combined branching fractions for ${\Lambda }_c^{+}\to \Lambda \omega {\pi }^{+}$ and ${\Lambda }_c^{+}\to \Lambda \eta {\pi }^{+}$ comprise $(87\mathrm{}\pm 13)\%$ of the total ${\Lambda }_c^{+}\to \Lambda {\pi }^{+}{\pi }^{+}{\pi }^{-}{\pi }^0$ rate. We set an upper limit on $\mathcal{B}({\Lambda }_c^{+}\to \Lambda {\pi }^{+}{\pi }^{+}{\pi }^{-}{\pi }^0)/\mathcal{B}({\Lambda }_c^{+}\to {\mathrm{pK}}^{-}{\pi }^{+})$ for non-ω and non-η modes of 0.13 at 90% confidence level.

We consider open strings ending on a D5-brane in the pp-wave background, which is realized in the Penrose limit of ${\mathrm{AdS}}_5\times {\mathrm{S}}^5$ with an ${\mathrm{AdS}}_4\times {\mathrm{S}}^2$ brane. A complete set of gauge invariant operators in the defect conformal field theory is constructed which is dual to the open-string states.

We consider supersymmetric $\mathrm{pp}$-wave limits for different $\mathcal{N}=1\mathrm{}$ orbifold geometries of the five-sphere ${\mathbf{S}}^5$ and the five-dimensional Einstein manifold ${\mathbf{T}}^{1,1}.$ As there are several interesting ways to take the Penrose limits, the $\mathrm{pp}$-wave geometry can be either maximally supersymmetric $\mathcal{N}=4\mathrm{}$ or half-maximally supersymmetric $\mathcal{N}=2.\mathrm{}$ We discuss in detail the cases ${\mathrm{AdS}}_5\times {\mathbf{S}}^5/{\mathbf{Z}}_3,$ ${\mathrm{AdS}}_5\times {\mathbf{S}}^5/({\mathbf{Z}}_m\times {\mathbf{Z}}_n),$ and ${\mathrm{AdS}}_5\times {\mathbf{T}}^{1,1}/({\mathbf{Z}}_m\times {\mathbf{Z}}_n)$ and we identify the gauge invariant operators that correspond to stringy excitations for the different limits.

Using a new approach, we propose an analogue of the Fizeau effect for massive and massless particles in an effective optical medium derived from the static, spherically symmetric gravitational field. The medium is naturally perceived as a dispersive medium by matter de Broglie waves. Several Fresnel drag coefficients are worked out, with appropriate interpretations of the wavelengths used. In two cases, it turns out that the coefficients become independent of the wavelength even if the equivalent medium itself is dispersive. A few conceptual issues are also addressed in the process of derivation. It is shown that some of our results complement recent work dealing with real fluid or optical black holes.

We investigate a method to evaluate quasinormal modes of D3-brane black holes by wave interpretation of fields on a D3-brane based on Feynman’s spacetime approach. We perturbatively solve the wave equation which describes propagation of a dilaton wave in a bulk space and its interaction with the D3-brane. The condition obtained for the quasinormal modes is qualitatively equivalent to that evaluated in the usual scattering of the dilaton in the black three-brane spacetime in the corresponding supergravity description.

A particular type of coupling of the dilaton field to the metric is shown to admit a simple geometric interpretation in terms of a volume element density independent from the metric. For dimension $n=4\mathrm{}$ two families of either magnetically or electrically charged static spherically symmetric solutions to the corresponding Maxwell-Einstein-dilaton field equations are derived. Whereas the metrics of the “magnetic” spacetimes are smooth, asymptotically flat, and have the topology of a wormhole, the “electric” metrics behave similarly as the singular and geodesically incomplete classical Reissner-Nordström metrics. At the price of losing the simple geometric interpretation, a closely related “alternative” dilaton coupling can nevertheless be defined, admitting as solutions smooth “electric” metrics.

We discuss interacting quantum field theory in de Sitter space and argue that the Mottola-Allen (MA) vacuum ambiguity is an artifact of free field theory. The nature of the nonthermality of the MA vacua is also clarified. We propose analyticity of correlation functions as a fundamental requirement of quantum field theory in curved spacetimes. In de Sitter space, this principle determines the vacuum unambiguously and facilitates the systematic development of perturbation theory.

One of the major predictions of inflation is the existence of a stochastic background of cosmological gravitational waves (GW). These gravitational waves can induce significant temperature anisotropies in the cosmic microwave background (CMB) on the angular scales recently probed by the Archeops experiment. Here, we perform a combined analysis of Archeops together with information from other CMB experiments and/or cosmological data sets, in order to constrain the amplitude of the GW background. We find that, for a scale-invariant GW background, the ratio of tensor-scalar perturbations at the CMB quadrupole is now constrained to be $r<~0.43$ at $95\%$ C.L., while the bound on the spectral index of primordial density fluctuations is $n_S{=0.97\mathrm{}}_{-0.12}^{+0.10\mathrm{}}.$ We discuss the implications for future GW detections through CMB polarization measurements.

We derive a quantum state of the disoriented chiral condensate dynamically, considering small quantum fluctuations around a classical chiral condensate disoriented in a certain direction $\overrightarrow{n}$ in isospace. The obtained nonisosinglet quantum state has the following characteristic features: (i) It has the form of the squeezed state; (ii) the state contains not only the component of pion quanta in the direction $\overrightarrow{n}$ but also the component in the perpendicular direction to $\overrightarrow{n};$ and (iii) the low momentum pions in the state violate the isospin symmetry. With the quantum state, we calculate the probability of the neutral fraction depending on the time and the pion’s momentum, and find that the probability has an unfamiliar form. For the low momentum pions, the parametric resonance mechanism works with the results that the probability of the neutral fraction becomes the well known form approximately, and that the charge fluctuation is small.

Nonleptonic charmless B decays into a pseudoscalar (P) or a vector (V) meson accompanying a tensor (T) meson are reanalyzed. We scrutinize the hadronic uncertainties and ambiguities of the form factors which appear in the literature. The Isgur-Scora-Grinstein-Wise updated model (ISGW2) is adopted to evaluate the relevant hadronic matrix elements. We calculate the branching ratios and $\mathrm{CP}$ asymmetries for various $\overrightarrow{B}P\left(V\right)T$ decay processes. With the ISGW2 model, the branching ratios are enhanced by about an order of magnitude compared to the previous estimates.

A model for a noncommutative scalar field coupled to gravity is proposed via an extension of the Moyal product. It is shown that there are solutions compatible with homogeneity and isotropy to first nontrivial order in the perturbation of the star product, with the gravity sector described by a flat Robertson-Walker metric. We show that in the slow-roll regime of a typical chaotic inflationary scenario, noncommutativity has negligible impact.

The singly Cabibbo-suppressed decays of charmed particles governed by the quark subprocesses $\overrightarrow{c}\mathrm{su}\overline{s}$ and $\overrightarrow{c}\mathrm{du}\overline{d}$ are analyzed using a flavor-topology approach, based on a previous analysis of the Cabibbo-favored decays governed by $\overrightarrow{c}\mathrm{su}\overline{d}.$ Decays to $\mathrm{PP}$ and $PV,$ where P is a pseudoscalar meson and V is a vector meson, are considered. We include processes in which $\eta$ and ${\eta }^{\prime }$ are produced.

We apply supersymmetric discrete light-cone quantization (SDLCQ) to the study of supersymmetric Yang-Mills–Chern-Simons (SYM-CS) theory on $\mathbf{R}\times S^1\times S^1.$ One of the compact directions is chosen to be lightlike and the other to be spacelike. Since the SDLCQ regularization explicitly preserves supersymmetry, this theory is totally finite, and thus we can solve for bound-state wave functions and masses numerically without renormalizing. The Chern-Simons term is introduced here to provide masses for the particles while remaining totally within a supersymmetric context. We examine the free, weak and strong-coupling spectrum. The transverse direction is discussed as a model for universal extra dimensions in the gauge sector. The wave functions are used to calculate the structure functions of the lowest mass states. We discuss the properties of Kaluza-Klein states and focus on how they appear at strong coupling. We also discuss a set of anomalously light states which are reflections of the exact Bogomol’nyi-Prasad-Sommerfield states of the underlying SYM theory.

We apply zeta-function regularization to the kink and supersymmetric (SUSY) kink and compute its quantum mass. We fix ambiguities in the renormalization by considering the asymptotic expansion of the vacuum energy as the mass gap tends to infinity (while keeping scattering data fixed) and dropping all terms proportional to non-negative powers or the logarithm of this mass gap. As an alternative we write the regulated sum over zero point energies in terms of the heat kernel and apply standard heat kernel subtractions with modifications which take the boundaries into account. Finally we discuss to what extent these procedures are equivalent to the usual renormalization condition that tadpoles vanish.

The origin of the anomalies is analyzed. It is shown that they are due to the fact that the generators of the symmetry do not leave the domain of definition of the Hamiltonian invariant and thus a term, normally forgotten in the Heisenberg equation, gives an extra contribution responsible for the nonconservation of the charges. This explanation is equivalent to that of Fujikawa in the path integral formalism. Finally, this approach is applied to conformal symmetry breaking in two-dimensional quantum mechanics.

We argue that states with nontrivial horizontal charges of a Bañados-Teitelboim-Zanelli (BTZ) black hole can be excited by ordinary falling matter including Hawking radiation. The matter effect does not break the integrability condition of the charges on the horizon. Thus we are able to trace the processes in which the matter imprints the information on the horizon by use of the charged states. It is naturally expected that in thermal equilibrium with the Hawking radiation the black hole wanders ergodically through different horizontal states due to thermal fluctuation of the incoming matter. This fact strengthens the plausibility of the basic part of Carlip’s idea. We also discuss some aspects of the quantum horizontal symmetry and conjecture how the precise black hole entropy will be given from our point of view.

We address the relation between the parameters of an accelerating brane universe embedded in five-dimensional bulk space. It is pointed out that the tiny cosmological constant of our world can be obtained as quantum corrections around a given brane solution in the bulk theory or in the field theory on the boundary from a holographic viewpoint. Some implications to the cosmology and constraints on the parameters are also given.

The cosmic no hair theorem is studied in anisotropic brane worlds. Assuming anisotropic Bianchi models with an inflaton field it is shown that, during slow-roll inflation, anisotropy in all Bianchi models except a Bianchi type-IX universe washes out. Brane worlds admit both exponential and power law inflation. We consider here only exponential expansion of the universe. It is found that isotropization occurs much faster in a brane world than in the general theory of relativity.

It is shown that within conformally flat stationary axisymmetric spacetimes, in addition to the locally static family, there exists a new class of metrics, which is always stationary and axisymmetric. All these spacetimes, the static and the stationary ones, are endowed with an arbitrary function depending on the two non-Killingian coordinates. The explicit form of this function can be determined once the coupled matter, i.e., the energy-momentum tensor, is given. The locally static branch allows for horizons, and hence for the existence of black hole solutions, while the intrinsic stationary axisymmetric family does not permit black holes. Since both classes of metrics allow for surfaces possessing an extrinsic curvature proportional to their intrinsic metrics, there is room for the possibility of constructing two-branes in these spacetimes.

A method for computing the stress-energy tensor for the quantized, massless, spin $\frac{1}{2}$ field in a general static spherically symmetric spacetime is presented. The field can be in a zero temperature state or a nonzero temperature thermal state. An expression for the full renormalized stress-energy tensor is derived. It consists of a sum of two tensors both of which are conserved. One tensor is written in terms of the modes of the quantized field and has zero trace. In most cases it must be computed numerically. The other tensor does not explicitly depend on the modes and has a trace equal to the trace anomaly. It can be used as an analytic approximation for the stress-energy tensor and is equivalent to other approximations that have been made for the stress-energy tensor of the massless spin $\frac{1}{2}$ field in static spherically symmetric spacetimes.