Logarithmically-accurate and positive-defnite NLO shower matching van Beekveld, Melissa Ferrario Ravasio, Silvia Helliwell, Jack Karlberg, Alexander Scyboz, Ludovic Soto-Ontoso, Alba Soyez, Gregory Zanoli, Silvia Higher-Order Perturbative Calculations Parton Shower Resummation We present methods to achieve NLL+NLO accurate parton showering for processes with two coloured legs: neutral- and charged-current Drell-Yan, and Higgs production in pp collisions, as well as DIS and e +e − to jets. The methods include adaptations of existing approaches, as well as a new NLO matching scheme, ESME, that is positive-defnite by construction. Our implementations of the methods within the PanScales framework yield highly competitive NLO event generation speeds. We validate the fxed-order and combined resummation accuracy with tests in the limit of small QCD coupling and briefy touch on phenomenological comparisons to standard NLO results and to Drell-Yan data. The progress reported here is an essential step towards showers with logarithmic accuracy beyond NLL for processes with incoming hadrons. 2025-10-27T12:02:53Z 2025-10-27T12:02:53Z 2025-10-03 journal article van Beekveld, M., Ferrario Ravasio, S., Helliwell, J. et al. Logarithmically-accurate and positive-definite NLO shower matching. J. High Energ. Phys. 2025, 38 (2025). https://doi.org/10.1007/JHEP10(2025)038 https://hdl.handle.net/10481/107491 10.1007/JHEP10(2025)038 eng info:eu-repo/grantAgreement/ERC/H2020/788223 http://creativecommons.org/licenses/by/4.0/ open access Atribución 4.0 Internacional Springer Nature