Tailored PDFs for New Physics searches
Ella Cole, Mark N. Costantini, Elie Hammou, Luca Mantani, Francesco Merlotti, Manuel Morales-Alvarado, Maria Ubiali

TL;DR
This paper explores optimal PDF choices for new physics searches at the LHC, balancing uncertainties and biases, and proposes simultaneous fits of PDFs and SMEFT coefficients to improve robustness in high-energy tail analyses.
Contribution
It systematically evaluates PDF fitting strategies and introduces a method for joint fitting of PDFs and SMEFT parameters for more reliable BSM searches.
Findings
Conservative PDFs reduce bias in high-x regions.
Simultaneous PDF and SMEFT fits account for correlations.
Recommended PDF strategies enhance BSM sensitivity.
Abstract
Given the non-negligible interplay between parton distribution functions (PDFs) at large x and potential New Physics (NP) effects in the high-energy tails of hadron collider observables, a central question is which PDFs can be reliably employed in beyond-the-Standard-Model (BSM) analyses. In this work, we examine the fine balance between using PDF sets with small uncertainties in the large-x region -- crucial for maximising BSM sensitivity -- and adopting conservative PDF fits that exclude high-energy data potentially contaminated by unaccounted NP contributions. We systematically assess a range of conservative PDF fitting strategies designed to mitigate such biases and provide a recommendation for the class of PDFs best suited for robust BSM searches. In addition, we investigate the alternative approach of performing simultaneous fits of Standard Model Effective Field Theory (SMEFT)…
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Taxonomy
TopicsParticle physics theoretical and experimental studies · High-Energy Particle Collisions Research · Computational Physics and Python Applications
