S
-wave elastic scattering of 
o
-Ps from 
H2
 at low energy
The confined variational method is applied to investigate the low-energy elastic scattering of ortho-positronium from $\text{H}_2$ by first-principles quantum mechanics. Describing the correlation effect with explicitly correlated Gaussians, we obtain accurate $S$-wave phase shifts and pick-off annihilation parameters for different incident momenta. By a least-squares fit of the data to the effective-range theory, we determine the $S$-wave scattering length, $A_s=2.06a_0$, and the zero-energy value of the pick-off annihilation parameter, $^1\!\text{Z}_\text{eff}=0.1858$. The obtained $^1\!\text{Z}_\text{eff}$ agrees well with the precise experimental value of $0.186(1)$ (J.\ Phys.\ B \textbf{16}, 4065 (1983)) and the obtained $A_s$ agrees well with the value of $2.1(2)a_0$ estimated from the average experimental momentum-transfer cross section for Ps energy below 0.3 eV (J.\ Phys.\ B \textbf{36}, 4191 (2003)).
First test of O(α2) correction of the orthopositronium decay rate
Positronium is an ideal system for the research of the bound state QED. New precise measurement of orthopositronium decay rate has been performed with an accuracy of 150 ppm. This result is consistent with the last three results and also the 2nd order correction. The result combined with the last three is 7.0401±0.0007µsec −1 (100 ppm), which is consistent with the 2nd order correction and differs from the 1st order calculation by 2.6�. It is the first test to validate the 2nd order correction.
Recovering the frontier state : war, ethnicity, and state in Afghanistan
Chapter 1 Table of Contents Chapter 2 1 Introduction Chapter 3 2 Ethnicity, Political Power, and Fragmentation Chapter 4 3 Rise of the Taliban and Civil War Chapter 5 4 The United States and War on Terrorism Chapter 6 5 Restructuring the Afghan State Chapter 7 6 Political Economy of Drugs and Warlordism Chapter 8 7 Afghanistan and Neighboring States Chapter 9 8 Conclusion Chapter 10 Bibliography