Production of vector mesons in the String+${}^3P_0$ model of polarized quark fragmentation

StringSpinner - adding spin to the PYTHIA string fragmentation

“…Each emitted hadron in string fragmentation is inspected by StringSpinner, which applies a veto procedure to emulate the rules of the string+ 3 P 0 model inspired by the standalone implementation of the model in Ref. [15]. The hadron h is rejected if it does not belong to the mupltiplets of (light or heavy) PS mesons or VMs, or if it is not produced from the fragmenting quark side.…”

“…which is inspired by the polarized splitting probability of the string+ 3 P 0 model in Ref. [15]. The vector k T is the transverse momentum of q with respect to the string axis and k T = k T /k T .…”

“…In this article we present a major extension of StringSpinner that includes the production and the decays of VMs in the polarized string fragmentation process of the Pythia event generator. For this purpose, we use the recently developed string+ 3 P 0 model with PS meson and VM production [15]. The model introduces two new free parameters to describe the relevant polarization states of the VMs.…”

Opportunities for precision QCD physics in hadronization at Belle II -- a snowmass whitepaper

“…Even though, initial measurements are available from Belle [72,73,103], these have to be expanded to probe the polarization dependent dynamics in detail. For example any final state other than pions is still poorly measured and the feed-down from spin-1 mesons to pions and kaons appears to play a significant role in these polarized fragmentation models [115]. As a first step, precise measurements of single-and di-hadron correlations with final state kaons need to be made.…”

“…As an example, Fig. 6 shows the partial wave projections of the stringspinner model [116] , which describes the z and invariant mass dependence of the di-hadron fragmentation well [114,115]. In principle this can be compared with the partial wave decomposition of di-hadron correlations from CLAS12, shown in Fig.…”