A Note on the Stringy Embeddings of Certain N = 2 Dualities

Seiberg-Witten theory can be embedded in F-theory using D3 branes probing an orientifold geometry. The non-perturbative corrections in the orientifold picture map directly to the instanton corrections in the corresponding gauge theory that convert the classical moduli space to the quantum one. In this short review we argue that the recently proposed class of conformal Gaiotto models may also be embedded in F-theory. The F-theory constructions help us not only to understand the Gaiotto dualities but also to extend to the non-conformal cases with and without cascading behaviors. For the conformal cases, the near horizon geometries in F-theory capture both the UV and IR behaviors succinctly.Comment: 6 pages, LaTeX, Based on the talk given by K. D at the Theory Canada Conference June 2012; v2: Typos corrected and references adde

Persistent Database Buffer Caching and Logging with Slotted Page Structure

Department of Computer Science and EngineeringEmerging byte-addressable persistent memory (PM) will be effective to improve the performance of computer system by reducing the redundant write operations. Traditional database management system uses recovery techniques to prevent data loss. The techniques copy the entire page into the block device storage several times for one insertion, so the amount of I/O is not negligible. In this work, we consider PM as main memory. Then, the durability of data in the buffer cache is ensured. To guarantee consistency, we exploit slotted page structure which is commonly used in database systems. We revisit that the slot header, which stores the metadata of the page in the slotted page structure, can act like a commit mark in the persistent database buffer cache. We then present two novel database management schemes using persistent buffer cache and slotted page. In-place commit scheme updates the page atomically using hardware transactional memory. It doesn't make any other copies and has optimal performance. Slot header logging scheme is needed for the case of updating pages more than one. Unlike the existing logging technique, slot header logging reduces the write operations by logging only commit mark. We implemented these schemes in SQLite and evaluate the performance compared with NVWAL, which is the state-of-the-art scheme. Our experiments show that in-place commit scheme needs only 3 cache line flush instructions for one insertion and slot header logging scheme reduces logging overhead at least 1/4.ope

Stress-tensor OPE in N=2 Superconformal Theories

We carry out a detailed superspace analysis of the OPE of two N=2 stress-tensor multiplets. Knowledge of the multiplets appearing in the expansion, together with the two-dimensional chiral algebra description of N=2 SCFTs, imply an analytic bound on the central charge c. This bound is valid for any N=2 SCFT regardless of its matter content and flavor symmetries, and is saturated by the simplest Argyres-Douglas fixed point. We also present a partial conformal block analysis for the scalar superconformal primary of the multiplet.Comment: 29 page

Geometrically Induced Metastability and Holography

We construct metastable configurations of branes and anti-branes wrapping 2-spheres inside local Calabi-Yau manifolds and study their large N duals. These duals are Calabi-Yau manifolds in which the wrapped 2-spheres have been replaced by 3-spheres with flux through them, and supersymmetry is spontaneously broken. The geometry of the non-supersymmetric vacuum is exactly calculable to all orders of the `t Hooft parameter, and to the leading order in 1/N. The computation utilizes the same matrix model techniques that were used in the supersymmetric context. This provides a novel mechanism for breaking supersymmetry in the context of flux compactifications.Comment: 42 pages, 5 figure