t-tbar Pair production cross section measurement at the LHC

Measurement of $t\bar{t}$ pair production cross sections with an integrated luminosity of around 1 fb$^{-1}$ at $\sqrt{s}$ = 7 TeV obtained with the ATLAS and CMS detectors are reported. The inclusive cross sections in dilepton (ee, $e\mu$, $\mu\mu$ and $\mu\tau$), lepton+jets (e, $\mu$) and all hadronic decay modes are measured. In addition to inclusive cross section measurement, the study of jet multiplicity with additional jets are also presented, which is important to constrain the initial state radiation. Measurement of the charge asymmetry at the LHC is also presented. All measurements are compatible with Standard Model predictions.Comment: Presented at the 2011 Hadron Collider Physics symposium (HCP-2011), Paris, France, November 14-18 2011, 5 pages, 7 figure

Disruption of Molecular Clouds by Expansion of Dusty H II Regions

Dynamical expansion of H II regions around star clusters plays a key role in dispersing the surrounding dense gas and therefore in limiting the efficiency of star formation in molecular clouds. We use a semi-analytic method and numerical simulations to explore expansion of spherical dusty H II regions and surrounding neutral shells and the resulting cloud disruption. Our model for shell expansion adopts the static solutions of Draine (2011) for dusty H II regions and considers the contact outward forces on the shell due to radiation and thermal pressures as well as the inward gravity from the central star and the shell itself. We show that the internal structure we adopt and the shell evolution from the semi-analytic approach are in good agreement with the results of numerical simulations. Strong radiation pressure in the interior controls the shell expansion indirectly by enhancing the density and pressure at the ionization front. We calculate the minimum star formation efficiency $\epsilon_{min}$ required for cloud disruption as a function of the cloud's total mass and mean surface density. Within the adopted spherical geometry, we find that typical giant molecular clouds in normal disk galaxies have $\epsilon_{min} \lesssim 10$%, with comparable gas and radiation pressure effects on shell expansion. Massive cluster-forming clumps require a significantly higher efficiency of $\epsilon_{min} \gtrsim 50$% for disruption, produced mainly by radiation-driven expansion. The disruption time is typically of the order of a free-fall timescale, suggesting that the cloud disruption occurs rapidly once a sufficiently luminous H II region is formed. We also discuss limitations of the spherical idealization.Comment: 23 pages, 14 figures; Accepted for publication in Ap

Development of Ocean Economy Satellite Account in Korea

The ocean has emerged as a new solution to new growth engines. However, some issues remain to be resolved, such as unified concepts and evaluation methods for the ocean economy, comparability between the national economy and the ocean economy, and the connection between global and national assessments. Since the ocean economy comprises various complex industries, it is necessary to establish policies based on an objective analysis of economic indicators. However, there have been difficulties in analyzing industrial activities related to the ocean economy within the national account system. To more accurately calculate the share of the ocean economy sector in the national economy, it is necessary to create a satellite account that reflects the characteristics of the ocean economic activities while maintaining consistency with the national account. This study aims to develop a satellite account for the ocean economy, a measurement of GDP in the ocean sector, which can correspond with the national accounts system and intends to propose Korean practices as a framework in the process of discussing international guidelines. This study introduces a potential structure for Korea\u27s ocean economy satellite account, the principles, methods, and data used for value coefficient estimation, and finally presents pilot results for several components of the ocean economy. This account can be utilized to diagnose the economic position as well as the policy effects of Korea’s ocean economy sector while contributing to the establishment of mid-to-long term industrial policies. This case study of Korean practices can be an important example that offers a framework and principles for international discussions

Numerical Modeling of Flow in Curved Channels with Various Sinuousness

Experimental and Computational Hydraulic