Light-cone gravity in dS4_4

We derive a closed form expression for the light-cone Lagrangian describing pure gravity on a four-dimensional de Sitter background. We provide a perturbative expansion, of this Lagrangian, to cubic order in the fields.Comment: 11 page

Does Financial Performance Influence Credit Ratings? An analysis of Korean KRX Firms

Credit rating agencies offer information about default risk. Previous literature suggests that firm’s credit ratings are influenced by various metrics, specifically, numerous risk considerations such as size, leverage and growth. However, there is limited evidence to support the relationship between credit ratings and financial performance. Our research is motivated by this caveat. The purpose of this paper is to discover if financial performance measures can be included as an indicator for default risk since the relation between financial performance and default risk/credit rating is a question left unanswered in a South Korean context. In this paper, we empirically test if financial performance measures can provide additional information about credit ratings and credit rating changes. We perform a battery of tests to establish if the following financial performance measures: EPS, CPS, ROA, ROE, and ROS have any explanatory power in explaining credit ratings levels and credit rating changes. Using a sample from 2002 to 2013, we find that EPS and CPS has a statistically positive relation to credit ratings, suggesting that firms with higher credit ratings have higher levels of EPS and CPS compared to firms with lower credit ratings. Moreover, we find that firms with positive performance measured by EPS and CPS in period t have the potential to experience a credit ratings change in period t+1. However, in South Korea, the majority of firms do not experience a credit ratings change. When we estimate the financial performance of the firms that do not experience a credit ratings change, we find a statistically significant relation between credit rating and financial performance for EPS and CPS. The results suggest that credit ratings for firms with positive financial performance remain stable Finally, we examine the relation between performance in period t and credit ratings increase and decrease in period t+1. The results suggest that the credit ratings of firms with high level of financial performances increase or remain the same. We do not find a relation between financial performance and credit rating decreases; this result may be due to our small sample size. The previous literature has largely ignored the association between credit ratings and performance. Taken together, our results suggests that EPS and CPS can be used as financial performance measures by investors, government agencies and debt issuers as additional information about a firms credit rating levels, and subsequent changes. We contribute to the literature by providing empirical evidence of a relationship between performance metrics and credit ratings, specifically the link between EPS

Farey sequence in the appearance of subharmonic Shapiro steps

Largest Lyapunov exponent has been examined in the dynamical-mode locking phenomena of the ac+dc driven dissipative Frenkel-Kontorova model with deformable substrate potential. Due to deformation, large fractional and higher order subharmonic steps appear in the response function of the system. Computation of the largest Lyapunov exponent as a way to verify their presence led to the observation of the Farey sequence. In the standard regime, between the large harmonic steps, the appearance of halfinteger and subharmonic steps, and their relative sizes follow the Farey construction. In the nonstandard regime, though halfinteger steps are larger than harmonic ones, Farey construction is still present in the appearance of higher order subharmonic steps. The examination of Lyapunov exponents also shows that there is no chaos in the system.Comment: 7 pages, 9 figure