SM@LHC 2026, Conference

Abstract

Indirect searches for new physics at the LHC increasingly rely on precision measurements in the high-energy tails of kinematic distributions, where uncertainties from Parton Distribution Functions (PDFs) are often a bottleneck. In this talk, I study the interplay between PDFs and Standard Model Effective Field Theory (SMEFT) interpretations in two key LHC sectors: Drell-Yan and top-quark production.

I compare two complementary strategies for robust PDF determination for new-physics searches: (i) simultaneous fits of PDFs and SMEFT Wilson coefficients, and (ii) sequential fits based on an initial conservative PDF determination using observables that can be reliably assumed to be SM-like. Both approaches are assessed through controlled closure tests in a realistic High-Luminosity LHC scenario.

I show how different fitting strategies impact PDF determination and SMEFT constraints and propose concrete best-practice recommendations for indirect new-physics searches in the Drell-Yan and top sectors at the LHC.