Experimental momentum spectra of identified hadrons in jets and the predictions from LPHD + MLLA

TL;DR

This paper compares experimental hadron momentum spectra from $e^+e^-$ colliders with MLLA + LPHD predictions, analyzing the energy dependence and hadron type effects to extract the strong coupling constant.

Contribution

It provides a quantitative test of MLLA + LPHD predictions for hadron spectra and determines $ ext{alpha}_s(m_Z)$ from the energy scaling of the spectra.

Findings

The energy dependence of $\xi_p^*$ matches perturbative predictions.

Hadron type influences the cut-off scale $Q_0$ in parton showers.

Extracted $ ext{alpha}_s(m_Z)$ consistent with world averages.

Abstract

Experimental data on the shape of hadronic momentum spectra are compared with theoretical predictions in the context of calculations in the Modified Leading Log Approximation (MLLA), under the assumption of Local Parton Hadron Duality (LPHD). Considered are experimental measurements at $e^+e^-$-colliders of $\xi_p^*$, the position of the maximum in the distribution of $\xi_p=\log(1/x_p)$, where $x_p=p/p_{beam}$. The parameter $\xi_p^*$ is determined for various hadrons at various centre of mass energies. It is interesting to look at the dependence of $\xi^*_p$ on the hadron type. This is used to study the influence of the hadron type on the cut-off scale $Q_0$ in the parton shower development. The dependence of $\xi^*_p$ on the centre of mass energy is seen to be described adequately by perturbation theory. The approach is made quantitative by extracting a value of $\alpha_s(m_Z)$ from an overall fit to the scaling behaviour of $\xi^*_p$.