SL(2,Z) Multiplets in N=4 SYM Theory

We discuss the action of SL(2,Z) on local operators in D=4, N=4 SYM theory in the superconformal phase. The modular property of the operator's scaling dimension determines whether the operator transforms as a singlet, or covariantly, as part of a finite or infinite dimensional multiplet under the SL(2,Z) action. As an example, we argue that operators in the Konishi multiplet transform as part of a (p,q) PSL(2,Z) multiplet. We also comment on the non-perturbative local operators dual to the Konishi multiplet.Comment: 14 pages, harvmac; v2: published version with minor change

D-branes in non-tachyonic 0B orientifolds

We determine all D-branes in the non-tachyonic 0'B orientifold, examine their world-volume anomalies and study orbifold compactifications. We find that the spectrum of the D-branes contains chiral fermions in the symmetric, antisymmetric and fundamental representations of (unitary) gauge groups on the branes. The cancellation of the world-volume anomalies requires Wess-Zumino terms which we determine explicitly. We examine a non-tachyonic compactification to 9D whose closed part interpolates between 0B and IIB and revisit compactifications on orbifolds. The D3-brane allows to conjecture, via the AdS/CFT correspondence, a supergravity dual to a non-supersymmetric and infrared-free gauge theory. The D-string gives hints concerning the S-dual of the 0'B orientifold.Comment: 38 pages, LaTeX, references added, eq.(100) generalized to contain the N-dependenc

Hawking-Page Phase Transition of black Dp-branes and R-charged black holes with an IR Cutoff

We show that the confinement-deconfinement phase transition of supersymmetric Yang-Mills theories with 16 supercharges in various dimensions can be realized through the Hawking-Page phase transition between the near horizon geometries of black Dp-branes and BPS Dp-branes by removing a small radius region in the geometry in order to realize a confinement phase, which generalizes the Herzog's discussion for the holographic hard-wall AdS/QCD model. Removing a small radius region in the gravitational dual corresponds to introducing an IR cutoff in the dual field theory. We also discuss the Hawking-Page phase transition between thermal $AdS_5$, $AdS_4$, $AdS_7$ spaces and R-charged AdS black holes coming from the spherical reduction of the decoupling limit of rotating D3-, M2-, and M5- branes in type IIB supergravity and 11 dimensional supergravity in grand canonical ensembles, where the IR cutoff also plays a crucial role in the existence of the phase transition.Comment: 34 pages, 18 figures, JHEP3, v2, references added, v3, some explanations adde

The X-ray reflector in NGC 4945: a time and space resolved portrait

We present a time, spectral and imaging analysis of the X-ray reflector in NGC 4945, which reveals its geometrical and physical structure with unprecedented detail. NGC 4945 hosts one of the brightest AGN in the sky above 10 keV, but it is only visible through its reflected/scattered emission below 10 keV, due to absorption by a column density of ~4\times10^24 cm-2. A new Suzaku campaign of 5 observations spanning ~6 months, together with past XMM-Newton and Chandra observations, show a remarkable constancy (within <10%) of the reflected component. Instead, Swift-BAT reveals strong intrinsic variability on time scales longer than one year. Modeling the circumnuclear gas as a thin cylinder with the axis on the plane of the sky, we show that the reflector is at a distance >30-50 pc, well within the imaging capabilities of Chandra at the distance of NGC 4945 (1"~18 pc). Accordingly, the Chandra imaging reveals a resolved, flattened, ~150 pc-long clumpy structure, whose spectrum is fully due to cold reflection of the primary AGN emission. The clumpiness may explain the small covering factor derived from the spectral and variability properties.Comment: 6 pages, 4 figures, 1 table. Accepted for publication in MNRA

Interlayer Magnetic Frustration in Quasi-stoichiometric Li1-xNi1+xO2

Susceptibility, high-field magnetization and submillimeter wave electron spin resonance measurements of layered quasi-stoichiometric Li1-xNi1+xO2 are reported and compared to isomorphic NaNiO2. A new mechanism of magnetic frustration induced by the excess Ni ions always present in the Li layers is proposed. We finally comment on the possible realization of an orbital liquid state in this controversial compound.Comment: 4 pages, 5 figures, submitted to Phys.Rev.B, Rapid Com

Running Scaling Dimensions in Holographic Renormalization Group Flows

Holographic renormalization group flows can be interpreted in terms of effective field theory. Based on such an interpretation, a formula for the running scaling dimensions of gauge-invariant operators along such flows is proposed. The formula is checked for some simple examples from the AdS/CFT correspondence, but can be applied also in non-AdS/non-CFT cases.Comment: 14 pages, 2 figure

Topologically Massive Gravity and the AdS/CFT Correspondence

We set up the AdS/CFT correspondence for topologically massive gravity (TMG) in three dimensions. The first step in this procedure is to determine the appropriate fall off conditions at infinity. These cannot be fixed a priori as they depend on the bulk theory under consideration and are derived by solving asymptotically the non-linear field equations. We discuss in detail the asymptotic structure of the field equations for TMG, showing that it contains leading and subleading logarithms, determine the map between bulk fields and CFT operators, obtain the appropriate counterterms needed for holographic renormalization and compute holographically one- and two-point functions at and away from the 'chiral point' (mu = 1). The 2-point functions at the chiral point are those of a logarithmic CFT (LCFT) with c_L = 0, c_R = 3l/G_N and b = -3l/G_N, where b is a parameter characterizing different c = 0 LCFTs. The bulk correlators away from the chiral point (mu \neq 1) smoothly limit to the LCFT ones as mu \to 1. Away from the chiral point, the CFT contains a state of negative norm and the expectation value of the energy momentum tensor in that state is also negative, reflecting a corresponding bulk instability due to negative energy modes.Comment: 54 pages, v2: added comments and reference

Three-Point Functions in N=4 SYM Theory at One-Loop

We analyze the one-loop correction to the three-point function coefficient of scalar primary operators in N=4 SYM theory. By applying constraints from the superconformal symmetry, we demonstrate that the type of Feynman diagrams that contribute depends on the choice of renormalization scheme. In the planar limit, explicit expressions for the correction are interpreted in terms of the hamiltonians of the associated integrable closed and open spin chains. This suggests that at least at one-loop, the planar conformal field theory is integrable with the anomalous dimensions and OPE coefficients both obtainable from integrable spin chain calculations. We also connect the planar results with similar structures found in closed string field theory.Comment: 34 pages, 9 figures, harvmac; references adde

ρ\rho - nucleus bound states in Walecka model

Possible formation of $\rho$ nucleus bound state is studied in the framework of Walecka model. The bound states are found in different nuclei ranging from $^3He$ to $^{208}Pb$. These bound states may have a direct bearing on the recent experiments on the photoproduction of $\rho$ meson in the nuclear medium.Comment: RevTeX fil

Internal magnetic fields and supersymmetry in orientifolds

Within the context of type I strings, we show the equivalence between BPS D9 branes with internal magnetic fluxes H_i in the three torii and non-BPS D3 branes with inverted internal magnetic fluxes 1/H_i. We then construct new supersymmetric examples of Z_2 x Z_2 orientifolds with discrete torsion which in the past had only non-supersymmetric solutions and emphasize the role of new twisted tadpole cancellation conditions, arising in the presence of magnetic fields, in order to get a consistent spectrum. In a second and independent part of the paper, we construct a new nine-dimensional type IIB orientifold with Scherk-Schwarz deformation which has the peculiarity of introducing a new type of non-BPS O9 planes and which contains as top branes a Scherk-Schwarz deformation of non-BPS D9 branes.The model contains charged D7 and D3 branes with a soft supersymmetry breaking spectrum.Comment: 26 pages, LaTeX, references adde