• M E ZOMORRODIAN

Articles written in Pramana – Journal of Physics

• Momentum distribution of charged particles in jets in dijet events and comparison to perturbative QCD predictions

Inclusive momentum distributions of charged particles are measured in dijet events. Events were produced at the AMY detector with a centre of mass energy of 60 ${\rm GeV}$. Our results were compared, on the one hand to those obtained from other $e^+ e^-$, $ep$ as well as CDF data, and on the other hand to the perturbative QCD calculations carried out in the framework of the modified leading log approximation (MLLA) and assuming local parton--hadron duality (LPHD). A fit of the shape of the distributions yields $\scr Q_{eff} = 263 \pm 13 {\rm MeV}$ for the AMY data. In addition, a fit to the evolution of the peak position with dijet mass using all data from different experiments gives $\scr Q_{eff} = 226 \pm 18 {\rm MeV}$. Next, αs was extracted using the shape of the distribution at the Z0 scale, with a value of 0.118 \pm 0.013. This is consistent, within the statistical errors, with many accurate measurements. We conclude that it is the success of LPHD + MLLA that the extracted value of $\alpha_{s}$ is correct. Possible explanations for all these features will be presented in this paper.

• The properties of $C$-parameter and coupling constants

We present the properties of the C-parameter as an event-shape variable. We calculate the coupling constants in the perturbative and also in the non-perturbative parts of the QCD theory, using the dispersive as wellas the shape function models. By fitting the corresponding theoretical predictions to our data, we find $\alpha_{s}(M_{Z^{0}} ) = 0.117 \pm 0.014$ and $\alpha_{0}(\mu_{I} ) = 0.491 \pm 0.043$ for dispersive model and $\alpha_{ s}(M_{Z^{0}} ) = 0.124 \pm 0.015$ and $\lambda_{1} = 1.234 \pm 0.052$ for the shape function model. Our results are consistent with the world average value of $\alpha_{s}(M_{Z^{0}} ) = 0.118 \pm 0.002$. All these features are explained in the main text.

• # Pramana – Journal of Physics

Volume 96, 2022
All articles
Continuous Article Publishing mode

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019