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MOHAMMAD EBRAHIM ZOMORRODIAN ALIREZA SEPEHRI TOORAJ GHAFFARY PARVIN ESLAMI 《Pramana》2011,76(1):93-107
The hadronic events from the e
+
e
− annihilation data at the centre-of-mass energies ranging from 60 to 197 GeV were studied. The AMY and OPAL Collaborations
offered a unique opportunity to test QCD by measuring the energy dependence of different observables. The coupling constant,
α
s, was measured by two different methods: first by employing the three-jet observables. Combining all the data, the value of
as at next-to-next leading order (NNLO) was determined to be 0.117 ± 0.004(hard) ± 0.006(theo). Secondly, from the event-shape
distributions, the strong coupling constant, α
s, was extracted at NNLO and it’s evaluation was tested with the energy scale. The results were consistent with the running
of α
s, expected from QCD predictions. Averaging over different observables, α
s was determined to be 0.115 ± 0.007(hard) ± 0.003(theo). 相似文献
2.
Using B3LYP/6-31G* density functional level of theory, the structural and optical properties of the C60 and M@C59X cages have been investigated. Results indicate that the charge on C atoms and band gap of C60 cage are changed dramatically with the substitution of one B or N atom at one of the C sites and the Li and Na atom encapsulations in the C60 cage. The Mulliken analyses show that the charge is transferred completely between the alkali atoms and the C59X cage. The substitutional and encapsulation doping (SED) reduce the optical gaps of the C60 cage. Also, the oscillator strengths of the absorption peaks are dependent on dopant types. 相似文献
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