PDF4LHC recommendations for LHC Run II

By J. Butterworth, Stefano Carrazza, A. Cooper-Sarkar, A. Roeck, J. Feltesse, S. Forte, Jun Gao, S. Glazov, J. Huston, Z. Kassabov and 6 more. 2015

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We provide an updated recommendation for the usage of sets of parton distribution functions (PDFs) and the assessment of PDF and PDF+$\alpha_s$ uncertainties suitable for applications at the LHC Run II. We review developments since the previous PDF4LHC recommendation, and discuss and compare the new generation of PDFs, which include substantial information from experimental data from the Run I of the LHC. We then propose a new prescription for the combination of a suitable subset of the available PDF sets, which is presented in terms of a single combined PDF set. We finally discuss tools which allow for the delivery of this combined set in terms of optimized sets of Hessian eigenvectors or Monte Carlo replicas, and their usage, and provide some examples of their application to LHC phenomenology.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/d5d6af5a4ac58d5d05bc929a0e5e7f7dd34167c0

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Citations in the corpus

Measurement of the W boson mass (2021, background): “[61] but this choice avoids further ad hoc scaling.”
Top-pair production at the LHC through NNLO QCD and NLO EW (2017, methodology): “ order to quantify the impact of the photon PDF, we use two recent PDF sets whose photon components are constructed within very dierent approaches. The rst set, LUXQED, is based on the PDF4LHC15 set [55] and adds to it a photon contribution that is derived from the structure function approach of ref”
Search for electroweak production of supersymmetric states in scenarios with compressed mass spectra at √s = 13 TeV with the ATLAS detector (2017, positive): “…] G e V [ 102 , 105 ] G e V [ 105 , 110 ] G e V [ 110 , 120 ] G e V [ 120 , 130 ] [ 100 , 102 ] G e V [ 102 , 105 ] G e V [ 105 , 110 ] G e V [ 110 , 120 ] G e V [ 120 , 130 ] with a corresponding signal strength parameter in a simultaneous fit of all CRs and relevant SRs; this is referred to as…”
Reweighting QCD matrix-element and parton-shower calculations (2016, methodology): “ most cases, as the PDF of the varied s is still tted to describe the same data as the PDF of the nominal s. This consistent s+PDF variation is also part of the PDF4LHC recommendations for LHC Run II [49]. The envelope of these s+PDF variations is taken as the respective uncertainty. The pure PDF un”
Les Houches 2017: Physics at TeV Colliders Standard Model Working Group Report (2017, methodology): “Each calculation used the PDF4LHCNNLO_30 PDFs [597], with its central value of αs(mZ) of 0.”
Search for electroweak production of charginos and neutralinos in multilepton final states in proton-proton collisions at s=13$$ \sqrt{s}=13 $$ TeV (2017, methodology): “The uncertainties from the PDFs are estimated by using the envelope of several PDF sets [69].”
Illuminating the photon content of the proton within a global PDF analysis (2017, neutral): “hibits somewhat smaller uncertainties. This is due to the use of a dierent set of quark and gluon PDFs determining the high-Q2 inelastic component, specically NNPDF3.1 rather than the PDF4LHC15 set [124] used in LUXqed16/17. The contribution from the dierent error sources is further illustrated in t”
NNLL-fast: predictions for coloured supersymmetric particle production at the LHC with threshold and Coulomb resummation (2016, methodology): “As our default choice for NNLL and approximated NNLO calculations, we use the NNLO PDF4LHC15 mc set of parton distribution functions (pdfs) [79].”
Parton distributions from high-precision collider data (2017, methodology): “ LHC Run II. Some of these have been used in the construction of the PDF4LHC15 combined sets, recommended for new physics searches and for the assessment of PDF uncertainties on precision observables [12]. These PDF4LHC15 sets are obtained by means of statistical combination of the three global sets”