An efficient representation of Euclidean gravity I
A bstractWe explore how the topology of spacetime fabric is encoded into the local structure of Riemannian metrics using the gauge theory formulation of Euclidean gravity. In part I, we provide a rigorous mathematical foundation to prove that a general Einstein manifold arises as the sum of SU(2)L Yang-Mills instantons and SU(2)R anti-instantons where SU(2)L and SU(2)R are normal subgroups of the four-dimensional Lorentz group Spin(4) = SU(2)L × SU(2)R. Our proof relies only on the general properties in four dimensions: The Lorentz group Spin(4) is isomorphic to SU(2)L × SU(2)R and the six-dimensional vector space Λ2T∗M of two-forms splits canonically into the sum of three-dimensional vector spaces of self-dual and anti-self-dual two-forms, i.e., $ {\Lambda^2}{T^{ * }}M = \Lambda_{ + }^2 \oplus \Lambda_{ - }^2 $. Consolidating these two, it turns out that the splitting of Spin(4) is deeply correlated with the decomposition of two-forms on four-manifold which occupies a central position in the theory of four-manifolds.

title: Black Hole as an Information Eraser
abstract: We discuss the identity of black hole entropy and show that the first law of black hole thermodynamics, in the case of a Schwarzschild black hole, can be derived from Landauer's principle by assuming that the black hole is one of the most efficient information erasers. The term "most efficient" implies that maximal information will be erased for a given amount of work. We calculate the discrete mass spectra and the entropy of a Schwarzschild black hole assuming that the black hole processes information in unit of bits. The black hole entropy acquires a subleading contribution proportional to the logarithm of its mass-squared in addition to the usual mass-squared term without an artificial cutoff. We also argue that the minimum of the black hole mass is $\sqrt{\log 2/(8\pi)}M_{\rm P}$.

title: Global and local D-vortices
abstract: Codimension-two objects on a system of brane-antibrane are studied in the context of Born-Infeld type effective field theory with a complex tachyon and U(1) × U(1) gauge fields. When the radial electric field is turned on in D2 ¯ D2, we find static regular global and local D-vortex solutions which could be candidates of straight cosmic D-strings in a superstring theory. A natural extension to DF-strings is briefly discussed.

title: BRANE WORLD OF WARP GEOMETRY: AN INTRODUCTORY REVIEW
abstract: Basic idea of Randall-Sundrum brane world model I and II is reviewed with detailed calculation. After introducing the brane world metric with exponential warp factor, metrics of Randall-Sundrum models are constructed. We explain how Randall-Sundrum model I with two branes makes the gauge hierarchy problem much milder, and derive Newtonian gravity in Randall-Sundrum model II with a single brane by considering small fluctuations.

title: ON WILSON SURFACES IN TOPOLOGICAL CHERN-SIMONS INTERACTION IN 3+1 DIMENSIONS
abstract: We comment on the regularization of the expectation values of Wilson surfaces for the bosonic string in 3+1 dimensions. We analyze the singular behaviors of propagators for the Chern-Simons action with the additional higher order terms.

title: BLACK STRING AND VELOCITY FRAME DRAGGING
abstract: We investigate velocity frame dragging with the boosted Schwarzschild black string solution and the boosted Kaluza–Klein bubble solution, in which a translational symmetry along the boosted z-coordinate is implemented. The velocity frame dragging effect can be nullified by the motion of an observer using the boost symmetry along the z-coordinate if it is not compact. However, in spacetime with the compact z-coordinate, we show that the effect cannot be removed since the compactification breaks the global Lorentz boost symmetry. As a result, the comoving velocity depends on r and the momentum parameter along the z-coordinate becomes an observer independent characteristic quantity of the black string and bubble solutions. The dragging induces a spherical ergo-region around the black string.

title: Large Nc volume reduction and chiral random matrix theory
abstract: Motivated by recent progress on the understanding of the Eguchi-Kawai (EK) volume equivalence and growing interest in conformal window, we simultaneously use the large-Nc volume reduction and Chiral Random Matrix Theory (chRMT) to study the chiral symmetry breaking of four dimensional SU(Nc) gauge theory with adjoint fermions in the large Nc limit. Although some cares are required because the chRMT limit and 't Hooft limit are not compatible in general, we show that the breakdown of the chiral symmetry can be detected in large-Nc gauge theories. As a first step, we mainly focus on the quenched approximation to establish the methodology. We first confirm that heavy adjoint fermions, introduced as the center symmetry preserver, work as expected and thanks to them the volume reduction holds. Using massless overlap fermion as a probe, we then calculate the low-lying Dirac spectrum for fermion in the adjoint representation to compare to that of chRMT, and find that chiral symmetry is indeed broken in the quenched theory.

title: A Reconnecting Current Sheet Imaged in a Solar Flare
abstract: Magnetic reconnection changes the magnetic field topology and powers explosive events in astrophysical, space, and laboratory plasmas. For flares and coronal mass ejections (CMEs) in the solar atmosphere, the standard model predicts the presence of a reconnecting current sheet, which has been the subject of considerable theoretical and numerical modeling over the last 50 years, yet direct, unambiguous observational verification has been absent. In this Letter, we show a bright sheet structure of global length (>0.25 R ?) and macroscopic width ((5-10)?103?km) distinctly above the cusp-shaped flaring loop, imaged during the flare rising phase in EUV. The sheet formed due to the stretch of a transequatorial loop system and was accompanied by various reconnection signatures. This unique event provides a comprehensive view of the reconnection geometry and dynamics in the solar corona.

title: On the Origin of Entropic Gravity and Inertia
abstract: It was recently suggested that quantum field theory is not fundamental but emerges from the loss of phase space information about matter crossing causal horizons. Possible connections between this formalism and Verlinde’s entropic gravity and Jacobson’s thermodynamic gravity are proposed. The holographic screen in Verlinde’s formalism can be identified as local Rindler horizons and its entropy as that of the bulk fields beyond the horizons. This naturally resolves some issues on entropic gravity. The quantum fluctuation of the fields is the origin of the thermodynamic nature of entropic gravity. It is also suggested that inertia is related to dragging Rindler horizons.

title: Phenomenology of the radion in the Randall–Sundrum scenario at colliders
abstract: Phenomenology of a radion ( φ ) that stabilizes the modulus in the Randall–Sundrum scenario is considered. The radion couples to the trace of energy momentum tensor of the standard model (SM) with a strength suppressed only by a new scale ( Λ φ ) of an order of the electroweak scale. In particular, the effective coupling of a radion to two gluons is enhanced due to the trace anomaly of QCD. Therefore, its production cross section at hadron colliders could be enhanced, and the dominant decay mode of a relatively light radion is φ → gg , unlike the SM Higgs boson case. We also present constraints on the mass m φ and the new scale Λ φ from the Higgs search limit at LEP and perturbative unitarity bound.

title: Characterisation and mitigation of beam-induced backgrounds observed in the ATLAS detector during the 2011 proton-proton run
abstract: This paper presents a summary of beam-induced backgrounds observed in the ATLAS detector and discusses methods to tag and remove background contaminated events in data. Trigger-rate based monitoring of beam-related backgrounds is presented. The correlations of backgrounds with machine conditions, such as residual pressure in the beam-pipe, are discussed. Results from dedicated beam-background simulations are shown, and their qualitative agreement with data is evaluated. Data taken during the passage of unpaired, i.e. non-colliding, proton bunches is used to obtain background-enriched data samples. These are used to identify characteristic features of beam-induced backgrounds, which then are exploited to develop dedicated background tagging tools. These tools, based on observables in the Pixel detector, the muon spectrometer and the calorimeters, are described in detail and their efficiencies are evaluated. Finally an example of an application of these techniques to a monojet analysis is given, which demonstrates the importance of such event cleaning techniques for some new physics searches.