Scattering on D3-branes

In a direct open string approach we analyze scattering of massless states on a stack of D3-branes. First we construct vertex operators on the D-branes. The 4+6 splitting for the fermionic part is made possible by inserting appropriately defined projection operators. With the vertex operators constructed we compute various tree amplitudes. The results are then compared with the corresponding field theory computations of the $\N=4$ SYM with \a'-corrections: agreements are found. We comment on applications to AdS/CFT.Comment: 15 pages, minor typos corrected, version that will appear in PL

Ghost condensation and CPT violation in neutrino sector

We consider CPT violation in neutrino sector, which is induced by ghost condensation. A model with extra dimension is suggested where ghost condensation occurs at a distant location separated from the SM brane. Right handed neutrinos in the bulk, which are originally introduced to explain small Yukawa couplings, play the role of messenger fields communicating ghost condensation and the standard model sector and lead to a sizable CPT violation in neutrino sector at the leading order. The model provides a resolution to the recent MINOS anomaly without spoiling any experimental constraints and may be able to be tested by observing an interesting phenomenon, twinkling cosmic microwave background radiation, with timescale about O(10-100) minutes at future CMB observations e.g. Planck.Comment: 11 pages, 1 figure

N3N^3 entropy of M5 branes from dielectric effect

We observe that the $N^3$ entropy behavior of near-extermal M5 branes can be reproduced from SYM side with the role of Myers' terms. We start by generalizing the Klebanov-Tseytlin (KT) supergravity solution that displays the $N^3$ entropy behavior. The new feature of the general solution is visibility of the "internal" degrees of the M5 branes, i.e., the M0 branes and the M2 branes. With the rationale provided by the supergravity analysis, we consider a D0 brane quantum mechanical setup with Myers' terms. Using localization technique, we show that the leading $N^3$ behavior of the free energy comes from the "classical contribution" with the rest sub-leading.Comment: latex, 21 pages, missing figure adde

Statistical Mechanics of Three-dimensional Kerr-de Sitter Space

The statistical computation of the (2+1)-dimensional Kerr-de Sitter space in the context of the {\it classical} Virasoro algebra for an asymptotic isometry group has been a mystery since first, the degeneracy of the states has the right value only at the infinite boundary which is casually disconnected from our universe, second, the analyses were based on the unproven Cardy's formula for complex central charge and conformal weight. In this paper, I consider the entropy in Carlip's "would-be gauge" degrees of freedom approach instead. I find that it agree with the Bekenstein-Hawking entropy but there are no the above problems. Implications to the dS/CFT are noted.Comment: Added comments about diffeomorphism generators and Wheeler-de Witt equation; Added references; Accpected in CQ

The Cross-sectional Return Predictability of Employment Growth:A Liquidity Risk Explanation

Employment growth (EG) is related to liquidity fundamentals of investment opportunities, firm health, and information environment and quality. This, in turn, implies that liquidity risk may play a role in explaining the relation between EG and stock returns. We find strong empirical evidence supporting the link between EG and liquidity risk. Stocks of high-EG firms are more liquid and exposed to lower liquidity risk than stocks of low-EG firms. After adjusting for liquidity risk, EG loses its power to predict returns

The Cross-sectional Return Predictability of Employment Growth:A Liquidity Risk Explanation

Employment growth (EG) is related to liquidity fundamentals of investment opportunities, firm health, and information environment and quality. This, in turn, implies that liquidity risk may play a role in explaining the relation between EG and stock returns. We find strong empirical evidence supporting the link between EG and liquidity risk. Stocks of high-EG firms are more liquid and exposed to lower liquidity risk than stocks of low-EG firms. After adjusting for liquidity risk, EG loses its power to predict returns

Probabilistic abstract interpretation: From trace semantics to DTMC’s and linear regression

In order to perform probabilistic program analysis we need to consider probabilistic languages or languages with a probabilistic semantics, as well as a corresponding framework for the analysis which is able to accommodate probabilistic properties and properties of probabilistic computations. To this purpose we investigate the relationship between three different types of probabilistic semantics for a core imperative language, namely Kozen’s Fixpoint Semantics, our Linear Operator Semantics and probabilistic versions of Maximal Trace Semantics. We also discuss the relationship between Probabilistic Abstract Interpretation (PAI) and statistical or linear regression analysis. While classical Abstract Interpretation, based on Galois connection, allows only for worst-case analyses, the use of the Moore-Penrose pseudo inverse in PAI opens the possibility of exploiting statistical and noisy observations in order to analyse and identify various system properties