NGAMMA: A Monte Carlo generator for multiphoton production in $e^{+}{e}^{-}$ annihilation

Abstract

We present the NGAMMA Monte Carlo event generator for QED processes of $e^{+}{e}^{-}$ annihilation into a multiphoton final state, $e^{+}{e}^{-}\to N\gamma (N\ge 2)$. These processes are an important source of background in the study of $e^{+}{e}^{-}\to hadrons$ processes with a multiphoton final state, especially for experiments at low energy $e^{+}{e}^{-}$ colliders like SND, CMD-3, KLOE and for the BESIII experiment. For generation, NGAMMA exploits the exact tree-level amplitude.

Comments: 8 pages, 6 figures, to be submitted to Comp. Phys. Commun