Infinite hierarchies of exact solutions of the Einstein and Einstein-Maxwell equations for interacting waves and inhomogeneous cosmologies

For space-times with two spacelike isometries, we present infinite hierarchies of exact solutions of the Einstein and Einstein--Maxwell equations as represented by their Ernst potentials. This hierarchy contains three arbitrary rational functions of an auxiliary complex parameter. They are constructed using the so called `monodromy transform' approach and our new method for the solution of the linear singular integral equation form of the reduced Einstein equations. The solutions presented, which describe inhomogeneous cosmological models or gravitational and electromagnetic waves and their interactions, include a number of important known solutions as particular cases.Comment: 7 pages, minor correction and reduction to conform with published versio

New AdS3AdS_3 Branes and Boundary States

We examine D-branes on $AdS_3$, and find a three-brane wrapping the entire $AdS_3$, in addition to 1-branes and instantonic 2-branes previously discussed in the literature. The three-brane is found using a construction of Maldacena, Moore, and Seiberg. We show that all these branes satisfy Cardy's condition and extract the open string spectrum on them.Comment: 18 pages, late

Nature of the light scalar mesons

Despite the apparent simplicity of meson spectroscopy, light scalar mesons cannot be accommodated in the usual $q\bar q$ structure. We study the description of the scalar mesons below 2 GeV in terms of the mixing of a chiral nonet of tetraquarks with conventional $q\bar q$ states. A strong diquark-antidiquark component is found for several states. The consideration of a glueball as dictated by quenched lattice QCD drives a coherent picture of the isoscalar mesons.Comment: 14 pages, 1 figure, accepted for publication in Phys. Rev.

Fuzzy sphere bimodule, ABS construction to the exact soliton solutions

In this paper, we set up the bi-module of the algebra ${\cal A}$ on fuzzy sphere. Based on the differential operators in moving frame, we generalize the ABS construction into fuzzy sphere case. The applications of ABS construction are investigated in various physical systems.Comment: Latex file without figure, 13 page

Fully Electrified Neugebauer Spacetimes

Generalizing a method presented in an earlier paper, we express the complex potentials E and Phi of all stationary axisymmetric electrovac spacetimes that correspond to axis data of the form E(z,0) = (U-W)/(U+W) , Phi(z,0) = V/(U+W) , where U = z^{2} + U_{1} z + U_{2} , V = V_{1} z + V_{2} , W = W_{1} z + W_{2} , in terms of the complex parameters U_{1}, V_{1}, W_{1}, U_{2}, V_{2} and W_{2}, that are directly associated with the various multipole moments. (Revised to clarify certain subtle points.)Comment: 25 pages, REVTE

Spontaneous generation of the Nambu --Jona-Lazinio interaction in quantum chromodynamics with two light quarks

In QCD with two light quarks with application of Bogolubov quasi-averages approach a possibility of spontaneous generation of an effective interaction, leading to the Nambu -- Jona-Lazinio model, is studied. Compensation equations for form-factor of the interaction is shown to have the non-trivial solution leading to theory with two parameters: average low-energy value of $\alpha_s$ and dimensional parameter $f_\pi$. All other parameters: the current and the constituent quark masses, the quark condensate, mass of $\pi$ meson, mass of $\sigma$ meson and its width are expressed in terms of the two initial parameters in satisfactory correspondence to experimental phenomenology. The results being obtained allow to state an applicability of the approach in the low-energy hadron physics and promising possibilities of its applications to other problems.Comment: 16 pages, 1 table, 3 figure

A new approach to calculate the gluon polarization

We derive the Leading-Order master equation to extract the polarized gluon distribution G(x;Q^2) = x \deltag(x;Q^2) from polarized proton structure function, g1p(x;Q^2). By using a Laplace-transform technique, we solve the master equation and derive the polarized gluon distribution inside the proton. The test of accuracy which are based on our calculations with two different methods confirms that we achieve to the correct solution for the polarized gluon distribution. We show that accurate experimental knowledge of g1p(x;Q^2) in a region of Bjorken x and Q^2, is all that is needed to determine the polarized gluon distribution in that region. Therefore, to determine the gluon polarization \deltag /g,we only need to have accurate experimental data on un-polarized and polarized structure functions (F2p (x;Q^2) and g1p(x;Q^2)).Comment: 12 pages, 5 figure

Photometric Variability in the Ultracool Dwarf BRI 0021-0214: Possible Evidence for Dust Clouds

We report CCD photometric monitoring of the nonemission ultracool dwarf BRI 0021-0214 (M9.5) obtained during 10 nights in 1995 November and 4 nights in 1996 August, with CCD cameras at 1 m class telescopes on the observatories of the Canary Islands. We present differential photometry of BRI 0021-0214, and we report significant variability in the I-band light curve obtained in 1995. A periodogram analysis finds a strong peak at a period of 0.84 day. This modulation appears to be transient because it is present in the 1995 data but not in the 1996 data. We also find a possible period of 0.20 day, which appears to be present in both the 1995 and 1996 datasets. However, we do not find any periodicity close to the rotation period expected from the spectroscopic rotational broadening (< 0.14 day). BRI 0021-0214 is a very inactive object, with extremely low levels of Halpha and X-ray emission. Thus, it is unlikely that magnetically induced cool spots can account for the photometric variability. The photometric variability of BRI 0021-0214 could be explained by the presence of an active meteorology that leads to inhomogeneous clouds on the surface. The lack of photometric modulation at the expected rotational period suggests that the pattern of surface features may be more complicated than previously anticipated.Comment: Accepted for publication in ApJ. 26 pages, 13 figures include

Dynamical generation of a nontrivial index on the fuzzy 2-sphere

In the previous paper hep-th/0312199 we studied the 't Hooft-Polyakov (TP) monopole configuration in the U(2) gauge theory on the fuzzy 2-sphere and showed that it has a nonzero topological charge in the formalism based on the Ginsparg-Wilson relation. In this paper, by showing that the TP monopole configuration is stabler than the U(2) gauge theory without any condensation in the Yang-Mills-Chern-Simons matrix model, we will present a mechanism for dynamical generation of a nontrivial index. We further analyze the instability and decay processes of the U(2) gauge theory and the TP monopole configuration.Comment: Latex2e, 30 pages, 4 figures, the topological charge for a monopole configuration is corrected, reference added, the final version to appear in Physical Review D (the typos mentioned in the erratum are corrected

Expanding impulsive gravitational waves

We explicitly demonstrate that the known solutions for expanding impulsive spherical gravitational waves that have been obtained by a "cut and paste" method may be considered to be impulsive limits of the Robinson-Trautman vacuum type N solutions. We extend these results to all the generically distinct subclasses of these solutions in Minkowski, de Sitter and anti-de Sitter backgrounds. For these we express the solutions in terms of a continuous metric. Finally, we also extend the class of spherical shock gravitational waves to include a non-zero cosmological constant.Comment: 11 pages, LaTeX, To appear in Class. Quantum Gra