Precision physics at the LHC requires the combination of fixed-order perturbative calculations with the simulation of multiple QCD radiation, which can be described through parton-shower (PS) algorithms, in order to obtain reliable predictions for experimental observables. In this context, simulation frameworks such as MG5$_$aMC@NLO and POWHEG have proven to be essential tools for achieving a consistent matching between next-to-leading-order (NLO) calculations and parton-shower effects.

In particular, POWHEG implements

\begin{equation} \sigma_{pw} =\int \text{d}\Phi_n \overline{B}(\Phi_n)\left( \Delta_{M} (\Phi_n,p_T^{min})+\int\text{d}\Phi_r\frac{R(\Phi_{n+1})}{B(\Phi_n)}\Delta_{M} (\Phi_n,p_T)\right), \end{equation}

where $\Delta_{M}(\Phi_n,p_T^{min})$ denotes the modified Sudakov form factor, which represents the probability of no emission above a given value of the ordering variable $p_T$. Unlike the Sudakov form factor implemented in standard parton-shower algorithms, it is constructed from the exact born $B(\Phi_n)$ and real $(R(\Phi_{n+1}))$ matrix elements.

In this presentation, I will discuss the work carried out during my graduate research, which focused on the implementation of an event generator for $t\bar{t}WW$ production at NLO QCD+PS within the POWHEG-BOX framework. This process constitutes a relevant background contribution to multilepton channels associated with $t\bar{t}t\bar{t}$ production, an important process in studies of the Higgs sector, as well as to other rare Standard Model processes that play a central role in precision measurements and indirect searches for new physics.

Our implementation provides more accurate differential predictions for this channel and represents an important step toward a systematic description of the $t\bar{t}VV$ family of processes at NLO+PS accuracy.

$t\bar{t}WW$ production at next-to-leading order NLO (QCD) + Parton Showers in the POWHEG-BOX at the LHC is presented