Matching perturbative and Parton Shower corrections to Bhabha process at   flavour factories
  We report on a high-precision calculation of the Bhabha process in Quantum Electrodynamics, of interest for precise luminosity determination of electron-positron colliders involved in R measurements in the region of hadronic resonances. The calculation is based on the matching of exact next-to-leading order corrections with a Parton Shower algorithm. The accuracy of the approach is demonstrated in comparison with existing independent calculations and through a detailed analysis of the main components of theoretical uncertainty, including two-loop corrections, hadronic vacuum polarization and light pair contributions. The calculation is implemented in an improved version of the event generator BABAYAGA with a theoretical accuracy of the order of 0.1%. The generator is now available for high-precision simulations of the Bhabha process at flavour factories. 
G. Balossini (1), C.M. Carloni Calame (2,1), G. Montagna (1,2), O.   Nicrosini (2,1), F. Piccinini (2,1) ((1) Dipartimento d...