Route to Direct Multiphoton Multiple Ionization
  We address the concept of direct multiphoton multiple ionization in atoms exposed to intense, short wavelength radiation and explore the conditions under which such processes dominate over the sequential. Their contribution is shown to be quite robust, even under intensity fluctuations and interaction volume integration, and reasonable agreement with experimental data is also found. 
P. Lambropoulos, G. M. Nikolopoulos, and K. G. Papamihail
quant-ph physics.atom-ph