Quasi-Normal Modes of Extremal BTZ Black Holes in TMG

We study the spectrum of tensor perturbations on extremal BTZ black holes in topologically massive gravity for arbitrary values of the coefficient of the Chern-Simons term, $\mu$. Imposing proper boundary conditions at the boundary of the space and at the horizon, we find that the spectrum contains quasi-normal modes.Comment: 18 pages, Latex, Ref's added, Typos correcte

Shading and Smothering of Gamma Ray Bursts

The gamma ray burst (GRB) 980425 is distinctive in that it seems to be associated with supernova (SN) 1998bw, has no X-ray afterglow, and has a single peak light curve and a soft spectrum. The supernova is itself unusual in that its expansion velocity exceeds c/6. We suggest that many of these features can be accounted for with the hypothesis that we observe the GRB along a penumbral line of sight that contains mainly photons that have scattered off ejected baryons. The hypothesis suggests a baryon poor jet (BPJ) existing within a baryon rich outflow. The sharp distinction can be attributed to whether or not the magnetic field lines thread an event horizon. Such a configuration suggests that there will be some non-thermal acceleration of pick-up ex-neutrons within the BPJ. This scenario might produce observable spallation products and neutrinos.Comment: 7 pages, 2 figures, submitted to ApJ

Local Compressibility Measurements of Correlated States in Suspended Bilayer Graphene

Bilayer graphene has attracted considerable interest due to the important role played by many-body effects, particularly at low energies. Here we report local compressibility measurements of a suspended graphene bilayer. We find that the energy gaps at filling factors v = 4 do not vanish at low fields, but instead merge into an incompressible region near the charge neutrality point at zero electric and magnetic field. These results indicate the existence of a zero-field ordered state and are consistent with the formation of either an anomalous quantum Hall state or a nematic phase with broken rotational symmetry. At higher fields, we measure the intrinsic energy gaps of broken-symmetry states at v = 0, 1 and 2, and find that they scale linearly with magnetic field, yet another manifestation of the strong Coulomb interactions in bilayer graphene.Comment: 9 pages, including 4 figures and supplementary material

Relativistic Photon Mediated Shocks

A system of equations governing the structure of a steady, relativistic radiation dominated shock is derived, starting from the general form of the transfer equation obeyed by the photon distribution function. Closure is obtained by truncating the system of moment equations at some order. The anisotropy of the photon distribution function inside the shock is shown to increase with increasing shock velocity, approaching nearly perfect beaming at upstream Lorentz factors $\Gamma_{-}>>1$. Solutions of the shock equations are presented for some range of upstream conditions. These solutions are shown to converge as the truncation order is increased.Comment: 5 pages, a shorter version will appear in PR

Proving Craig and Lyndon Interpolation Using Labelled Sequent Calculi

We have recently presented a general method of proving the fundamental logical properties of Craig and Lyndon Interpolation (IPs) by induction on derivations in a wide class of internal sequent calculi, including sequents, hypersequents, and nested sequents. Here we adapt the method to a more general external formalism of labelled sequents and provide sufficient criteria on the Kripke-frame characterization of a logic that guarantee the IPs. In particular, we show that classes of frames definable by quantifier-free Horn formulas correspond to logics with the IPs. These criteria capture the modal cube and the infinite family of transitive Geach logics

Erratum to: The contribution of bank regulation and fair value accounting to procyclical leverage

Abstract Our analysis of how banks’ responses to asset price changes can result in procyclical leverage reveals that, for banks with a binding regulatory leverage constraint, absent differences in regulatory risk weights across assets, procyclical leverage does not occur. For banks without a binding constraint, fair value and bank regulation both can contribute to procyclical leverage. Empirical findings based on a large sample of U.S. commercial banks reveal that bank regulation explains procyclical leverage for banks relatively close to the regulatory leverage constraint and contributes to procyclical leverage for those that are not. We also show that fair value accounting does not contribute to procyclical leverage

Two chiral nonet model with massless quarks

We present a detailed study of a linear sigma model containing one chiral nonet transforming under U(1)$_A$ as a quark-antiquark composite and another chiral nonet transforming as a diquark-anti diquark composite (or, equivalently from a symmetry point of view, as a two meson molecule). The model provides an intuitive explanation of a current puzzle in low energy QCD: Recent work has suggested the existence of a lighter than 1 GeV nonet of scalar mesons which behave like four quark composites. On the other hand, the validity of a spontaneously broken chiral symmetric description would suggest that these states be chiral partners of the light pseudoscalar mesons, which are two quark composites. The model solves the problem by starting with the two chiral nonets mentioned and allowing them to mix with each other. The input of physical masses in the SU(3) invariant limit for two scalar octets and an "excited" pion octet results in a mixing pattern wherein the light scalars have a large four quark content while the light pseudoscalars have a large two quark content. One light isosinglet scalar is exceptionally light. In addition, the pion pion scattering is also studied and the current algebra theorem is verified for massless pions which contain some four quark admixture.Comment: 22 pages, 8 figure

Statistical isotropy of the Cosmic Microwave Background

The breakdown of statistical homogeneity and isotropy of cosmic perturbations is a generic feature of ultra large scale structure of the cosmos, in particular, of non trivial cosmic topology. The statistical isotropy (SI) of the Cosmic Microwave Background temperature fluctuations (CMB anisotropy) is sensitive to this breakdown on the largest scales comparable to, and even beyond the cosmic horizon. We propose a set of measures, $\kappa_\ell$ ($\ell=1,2,3, ...$) which for non-zero values indicate and quantify statistical isotropy violations in a CMB map. We numerically compute the predicted $\kappa_\ell$ spectra for CMB anisotropy in flat torus universe models. Characteristic signature of different models in the $\kappa_\ell$ spectrum are noted.Comment: Presented at PASCOS'03, January 3-8, 2003, in TIFR, Mumbai; to be published in a special issue of 'Pramana' (4 pages, 1 figure, style files included

Pengaruh Karakteristik Perusahaan Dan Corporate Governance Terhadap Publikasi Sustainability Report (Studi Empiris Pada Perusahaan Lq45 Yang Terdaftar Di Bei Tahun 2011-2014)

Publication of Sustainability Report (SR) in Indonesia is still voluntary, but the interests and priorities of the companies to publish SR increases. This research aims to determine the effect of the characteristics of the company and corporate governance consists of activity analysis, size, audit committee, and board of directors on the publication of sustainability report in LQ45 companies listed in Indonesian Stock Exchange (IDX) in 2011-2014. The data used in this research were secondary data from companies\u27 financial data listed in Indonesian Stock Exchange. The sampling methods used was non-probability sampling, which is purposive sampling method. From the population of 78 companies listed in the index of LQ45 during 2011-2014, they were counted 12 companies that fill up the criterias. The hypothesis tested by using logistic regression analysis. The results of the hypothesis test showed that activity analysis, size, and board of directors are having significant effects on the publication of sustainability report with 0.01, 0.03 and 0.04 significance. While the audit committee has no significant effect with 0.236 significance. The influence of the characteristics of the company and corporate governance is 65.5% while the remaining 34.5% is influenced by other variables