Gravitational wave from warm inflation

A fundamental prediction of inflation is a nearly scale-invariant spectrum of gravitational wave. The features of such a signal provide extremely important information about the physics of the early universe. In this paper, we focus on several topics about warm inflation. First, we discuss the stability property about warm inflation based on nonequilibrium statistical mechanics, which gives more fundamental physical illustrations to thermal property of such model. Then, we calculate the power spectrum of gravitational waves generated during warm inflation, in which there are three components contributing to such spectrum: thermal term, quantum term and cross term combining the both. We also discuss some interesting properties about these terms and illustrate them in different panels. As a model different from cold inflation, warm inflation model has its individual properties in observational practice, so we finally give a discussion about the observational effect to distinguish it from cold inflation.Comment: 11 pages, 2 figure

The Causality and Economic Impact of FDI inflows from Trade Partners in Pakistan

This paper examines causality between FDI, GDP, Exports and Domestic Investment by using Granger and multivariate Granger causality tests. The study also employs gravity based panel model to investigate the impact of FDI inflows from trade partners on GDP, trade and domestic investment in Pakistan. The results show that two-way causality runs between GDP, domestic investment and FDI, while unidirectional causality is detected from exports to FDI. Our panel data estimation confirms the positive role of FDI inflows in GDP and domestic investment while the results shows that the role of FDI is insignificant in case of exports and imports. Similarly, the concentration and sporadic FDI inflows from a few trade partners is adversely affecting GDP and increases imports without affecting domestic investment and exports. On the other hand minor FDI inflows from trade partners significantly contribute to GDP and decreases imports.trade partners, causality, gravity model, concentration

M5-branes and Wilson Surfaces

We investigate the M5-brane description of the Wilson surface operators in six-dimensional (2,0) superconformal field theory from AdS/CFT correspondence. We consider the Wilson surface operators in high-dimensional representation, whose description could be M5-brane string soliton solutions in $AdS_7\times S^4$ background. We construct such string soliton solutions from the covariant M5-brane equations of motion and discuss their properties. The supersymmetry analysis shows that these solutions are half-BPS. We also discuss the subtle issue on the boundary terms.Comment: 30 pages, Latex; little revision;Typos corrected, references added, JHEP published versio