Perturbing Around A Warped Product Of AdS_4 and Seven-Ellipsoid

We compute the spin-2 Kaluza-Klein modes around a warped product of AdS_4 and a seven-ellipsoid. This background with global G_2 symmetry is related to a U(N) x U(N) N=1 superconformal Chern-Simons matter theory with sixth order superpotential. The mass-squared in AdS_4 is quadratic in G_2 quantum number and KK excitation number. We determine the dimensions of spin-2 operators using the AdS/CFT correspondence. The connection to N=2 theory preserving SU(3) x U(1)_R is also discussed.Comment: 21pp; The second and last paragraphs of section 2, the footnotes 1 and 2 added and to appear in JHE

Geometrically Induced Phase Transitions at Large N

Utilizing the large N dual description of a metastable system of branes and anti-branes wrapping rigid homologous S^2's in a non-compact Calabi-Yau threefold, we study phase transitions induced by changing the positions of the S^2's. At leading order in 1/N the effective potential for this system is computed by the planar limit of an auxiliary matrix model. Beginning at the two loop correction, the degenerate vacuum energy density of the discrete confining vacua split, and a potential is generated for the axion. Changing the relative positions of the S^2's causes discrete jumps in the energetically preferred confining vacuum and can also obstruct direct brane/anti-brane annihilation processes. The branes must hop to nearby S^2's before annihilating, thus significantly increasing the lifetime of the corresponding non-supersymmetric vacua. We also speculate that misaligned metastable glueball phases may generate a repulsive inter-brane force which stabilizes the radial mode present in compact Calabi-Yau threefolds.Comment: 47 pages, 7 figure

ZZ-Branes of N=2 Super-Liouville Theory

We study conformal boundary conditions and corresponding one-point functions of the N=2 super-Liouville theory using both conformal and modular bootstrap methods. We have found both continuous (`FZZT-branes') and discrete (`ZZ-branes') boundary conditions. In particular, we identify two different types of the discrete ZZ-brane solutions, which are associated with degenerate fields of the N=2 super-Liouville theory.Comment: 26 page

Cosmological Lower Bound on Dark Matter Masses from the Soft Gamma-ray Background

Motivated by a recent detection of 511 keV photons from the center of our Galaxy, we calculate the spectrum of the soft gamma-ray background of the redshifted 511 keV photons from cosmological halos. Annihilation of dark matter particles into electron-positron pairs makes a substantial contribution to the gamma-ray background. Mass of such dark matter particles must be <~ 100 MeV so that resulting electron-positron pairs are on-relativistic. On the other hand, we show that in order for the annihilation not to exceed the observed background, the dark matter mass needs to be >~ 20 MeV. We include the contribution from the active galactic nuclei and supernovae. The halo substructures may increase the lower bound to >~ 60 MeV.Comment: 5 pages, 5 figures; accepted for publication in PRD, Rapid Communicatio

Effect of Electron Beam Irradiation and Storage on the Quality Attributes of Sausages with Different Fat Contents

Sausages with different fat contents (16 or 29%) were purchased from local stores, vacuum-packaged in oxygen-impermeable bags, and irradiated at 0 or 5 kGy using a linear accelerator. The changes in quality attributes of irradiated sausages were determined during storage at 4°C. The 2-thiobarbituric acid-reactive substance values of sausages were not affected by fat content but were increased after irradiation (5 kGy). Storage for 60 d increased the 2-thiobarbituric acid-reactive substance values of nonirradiated sausages (P \u3c 0.05) but had no effect on irradiated sausages. The numbers of volatile compounds and the amounts of total volatiles were increased by irradiation in both the high-fat (29% fat) and low-fat (16% fat) sausages. Dimethyl sulfide was detected only in irradiated sausages, regardless of fat content (P \u3c 0.05), but it disappeared after 60 d of storage. Pentane and 1-heptene were detected only in irradiated samples after 60 d of storage. Low-fat sausages had greater L* values, but had lesser a* and b* values than high-fat sausages. Irradiation and storage had little effect on either the exterior or interior color (L*, a*, and b* values) of sausages. Fat content had no effect on the sensory variables of sausages, regardless of irradiation and storage. However, irradiated sausages had significantly stronger off-odors and off-flavors than nonirradiated sausages regardless of fat content (P \u3c 0.05). This indicated that fat content in sausages had a minimal effect on the quality of irradiated sausages during storage