Multiplicative-accumulative matching of NLO calculations with parton showers

We propose a new approach for combining next-to-leading order (NLO) and parton shower (PS) calculations so as to obtain three core features: (a) applicability to general showers, as with the MC@NLO and POWHEG methods; (b) positive-weight events, as with the KrkNLO and POWHEG methods; and (c) all showering attributed to the parton shower code, as with the MC@NLO and KrkNLO methods. This is achieved by using multiplicative matching in phase space regions where the shower overestimates the matrix element and accumulative (additive) matching in regions where the shower underestimates the matrix element, an approach that can be viewed as a combination of the MC@NLO and KrkNLO methods.

Automated summary

The proposed approach combines the features of the MC@NLO and KrkNLO methods to achieve a combination of NLO and parton shower calculations. It aims to provide applicability to general showers, positive-weight events, and attribute all showering to the parton shower code. This is achieved through multiplicative and accumulative matching in different phase space regions.