I present a new computational paradi gm to simulate time and momentum resolved inelastic scattering spectroscop ies in correlated systems. The conventional calculation of scattering cros s sections relies on a treatment based on time-dependent perturbation theo ry\, that provides formulation in terms of Green&rsquo\;s functions. In eq uilibrium\, it boils down to evaluating a simple spectral function equival ent to Fermi&rsquo\;s golden rule\, which can be solved efficiently by a n umber of numerical methods. However\, away from equilibrium\, the resultin g expressions require a full knowledge of the excitation spectrum and eige nvectors to account for all the possible allowed transitions\, a seemingly unsurmountable complication. Similar problems arise when the quantity of interest originates from higher order processes\, such as in Auger\, Raman \, or resonant inelastic X-ray scattering (RIXS). To circumvent these hurd les\, we introduce a time-dependent approach that does not require a full diagonalization of the Hamiltonian: we simulate the full scattering proces s\, including the incident and outgoing particles (neutron\, electron\, ph oton) and the interaction terms with the sample\, and we solve the time-de pendent Schrö\;dinger equation. The spectrum is recovered by measuring the momentum and energy lost by the scattered particles\, akin an actual energy-loss experiment. \;The method can be used to study transient dy namics and spectral signatures of correlation-driven non-equilibrium proce sses\, as I illustrate with several examples and experimental proposals us ing the time-dependent density matrix renormalization group method as a so lver. \;Even in equilibrium\, we find higher order contributions to th e spectra that can potentially be detected by modern instruments. < /span>

\n DTSTART:20210408T183000Z LOCATION:via Zoom\, Room Online SUMMARY:A time-dependent approach to inelastic scattering spectroscopies in and away from equilibrium: beyond perturbation theory END:VEVENT END:VCALENDAR