Parton distributions in the SMEFT from high-energy Drell-Yan tails

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Greljo, A 
Iranipour, S 
Kassabov, Z 
Moore, J 

The high-energy tails of charged- and neutral-current Drell-Yan processes provide important constraints on the light quark and anti-quark parton distribution functions (PDFs) in the large-x region. At the same time, short-distance new physics effects such as those encoded by the Standard Model Effective Field Theory (SMEFT) would induce smooth distortions to the same high-energy Drell-Yan tails. In this work, we assess for the first time the interplay between PDFs and EFT effects for high-mass Drell-Yan processes at the LHC and quantify the impact that the consistent joint determination of PDFs and Wilson coefficients has on the bounds derived for the latter. We consider two well-motivated new physics scenarios: 1) electroweak oblique corrections (Ŵ , Ŷ) and 2) four-fermion interactions potentially related to the LHCb anomalies in R(K(*)). We account for available Drell-Yan data, both from unfolded cross sections and from searches, and carry out dedicated projections for the High-Luminosity LHC. Our main finding is that, while the interplay between PDFs and EFT effects remains moderate for the current dataset, it will become a significant challenge for EFT analyses at the HL-LHC.

Phenomenological Models, QCD Phenomenology
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Journal of High Energy Physics
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Springer Science and Business Media LLC
Royal Society (DH150088)
Royal Society (RGF/EA/180148)
STFC (ST/T000694/1)
European Commission Horizon 2020 (H2020) ERC (206409)
STFC (1948592)
We thank Emanuele Mereghetti, Tevong You and Celine Degrande for insightful discussions about the project. We thank Claude Duhr and Bernhard Mistlberger for kindly sending us the NNLO and N3LO QCD corrections for the Drell-Yan invariant and transverse mass distributions. We thank Andrea Wulzer and Lorenzo Ricci for benchmarking the charged current K-factors and for suggesting to add the results obtained by using conservative PDFs. M. U. and Z. K. are supported by the European Research Council under the European Union’s Horizon 2020 research and innovation Programme (grant agreement n.950246). M. U. and S. I. are supported by the Royal Society grant RGF/EA/180148. The work of M. U. is also funded by the Royal Society grant DH150088. The work of J. R. is partially supported by the Netherlands Science Council (NWO). The work of A. G. has received funding from the Swiss National Science Foundation (SNF) through the Eccellenza Professorial Fellowship “Flavor Physics at the High Energy Frontier” project number 186866, and is also partially supported by the European Research Council under the European Union’s Horizon 2020 research and innovation programme, grant agreement 833280 (FLAY). The work of J. M. is supported by the Sims Fund Studentship. The work of M. M. is supported by the University of Cambridge Schiff Foundation studentship. C. V. is supported by the STFC grant ST/R504671/1. M. U., S. I., Z. K., J. M. and M. M. are partially supported by STFC consolidated grants ST/P000681/1, ST/T000694/1.