Tuning and validation of hadronic event generator for R value measurements in the tau-charm region

To measure the R value in an energy scan experiment with e(+)e(-) collisions, precise calculation of initial state radiation is required in the event generators. We present an event generator for this consideration, which incorporates initial state radiation effects up to second order accuracy. The radiative correction factor is calculated using the totally hadronic Born cross section. The measured exclusive processes are generated according to their cross sections, while the unknown processes are generated using the LUND Area Law model, and its parameters are tuned with data collected at root s = 3.65 GeV. The optimized values are validated with data in the range root s = 2.2324-3.671 GeV. These optimized parameters are universally valid for event generation below the DD threshold.