Applying different angular ordering constraints and $k_t$-factorization approaches to the single inclusive hadron production in the $e^+e^-$ annihilation processes

Abstract

We study the differential cross section of the single inclusive e + e − annihilation to the hadrons via γ-production, in the different k t -factorization frameworks. In order to take into account the transverse momenta of the incoming partons, for the first time, we apply the Kimber et al (KMR) method to calculate the unintegrated parton fragmentation functions (UFFs) from the ordinary integrated one, i.e., the parton fragmentation functions (FFs), which satisfy the similar DGLAP evolution equations, such as those of parton distribution functions (PDFs). Also, by utilizing the different angular ordering constraints the results corresponding to the Martin et al (MRW) in the leading order (LO) and the next-to-leading-order (NLO) are obtained. The LO sets of DSS library for the input FFs is used. The numerical results are compared with the experimental data in the different energies which are reported by the different collaborations, such as TASSO, AMY, MARK II, CELLO, DELPHI, SLD, ALEPH and Belle with the other QCD+fragmentation models such as Pythia 6.4 and 8.2 parton showers. The behaviors of the normalized differential cross sections and the multiplicity versus the "transverse momentum" (p ⊥ ) are discussed. The final results demonstrate that the KMR and MRW UFFs give a good description of data and there is not much significant difference between the above three schemes. On the other hand, our results become closer to the data for the lower values of p ⊥ and the higher values of center of mass energies.