Single top production in PDF fits

Nocera, Emanuele R.; Ubiali, Maria; Voisey, Cameron

doi:10.1007/jhep05(2020)067

Cited by 22 publications

(37 citation statements)

References 92 publications

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“…We can see that the agreement is good in all cases, albeit within rather large experimental uncertainties. There is in particular no sign of any similar significant disagreement to that observed [167] in certain distributions in the ATLAS 7 TeV measurement (though not the 8 TeV). We show the corresponding comparison to the 7 TeV top and anti-top rapidity and p ⊥ distributions [168] in Fig.…”

Section: Predictions For a Selection Of Lhc Processessupporting

confidence: 44%

Parton distributions from LHC, HERA, Tevatron and fixed target data: MSHT20 PDFs

Bailey¹,

et al. 2021

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We present the new MSHT20 set of parton distribution functions (PDFs) of the proton, determined from global analyses of the available hard scattering data. The PDFs are made available at NNLO, NLO, and LO, and supersede the MMHT14 sets. They are obtained using the same basic framework, but the parameterisation is now adapted and extended, and there are 32 pairs of eigenvector PDFs. We also include a large number of new data sets: from the final HERA combined data on total and heavy flavour structure functions, to final Tevatron data, and in particular a significant number of new LHC 7 and 8 TeV data sets on vector boson production, inclusive jets and top quark distributions. We include up to NNLO QCD corrections for all data sets that play a major role in the fit, and NLO EW corrections where relevant. We find that these updates have an important impact on the PDFs, and for the first time the NNLO fit is strongly favoured over the NLO, reflecting the wider range and in particular increased precision of data included in the fit. There are some changes to central values and a significant reduction in the uncertainties of the PDFs in many, though not all, cases. Nonetheless, the PDFs and the resulting predictions are generally within one standard deviation of the MMHT14 results. The major changes are the $$u-d$$ u - d valence quark difference at small x, due to the improved parameterisation and new precise data, the $${\bar{d}}, {\bar{u}}$$ d ¯ , u ¯ difference at small x, due to a much improved parameterisation, and the strange quark PDF due to the effect of LHC W, Z data and inclusion of new NNLO corrections for dimuon production in neutrino DIS. We discuss the phenomenological impact of our results, and in general find reduced uncertainties in predictions for processes such as Higgs, top quark pair and W, Z production at post LHC Run-II energies.

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Section: Predictions For a Selection Of Lhc Processessupporting

confidence: 44%

Parton distributions from LHC, HERA, Tevatron and fixed target data: MSHT20 PDFs

Bailey¹,

et al. 2021

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“…for PDF fits has been studied before in ref. [97]. To further improve the accuracy of our predictions, NLO off-shell effects implemented in MCFM [33] could be incorporated with a reweighting procedure.…”

Section: Jhep02(2021)040mentioning

confidence: 99%

Single-top-quark production in the t-channel at NNLO

Campbell

Neumann

Sullivan

2021

J. High Energ. Phys.

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We present a calculation of t-channel single-top-quark production and decay in the five-flavor scheme at NNLO. Our results resolve a disagreement between two previous calculations of this process that found a difference in the inclusive cross section at the level of the NNLO coefficient itself. We compare in detail with the previous calculations at the inclusive, differential and fiducial level including b-quark tagging at a fixed scale μ = mt. In addition, we advocate the use of double deep inelastic scattering (DDIS) scales (μ2 = Q2 for the light-quark line and μ2 = Q2 + $$ {m}_t^2 $$ m t 2 for the heavy-quark line) that maximize perturbative stability and allow for robust scale uncertainties. All NNLO and NLO⊗NLO contributions for production and decay are included in the on-shell and vertex-function approximation. We present fiducial and differential results for a variety of observables used in Standard Model and Beyond Standard Model analyses, and find an important difference between the NLO and NNLO predictions of exclusive t + n-jet cross sections. Overall we find that NNLO corrections are crucial for a precise identification of the t-channel process.

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“…In all cases, the value of χ 2 per data point correspond to the definition given in Eqs. (3.2)-(3.3) in [50]. The values in square brackets are for datasets not included in the corresponding fit.…”

Section: Fit Qualitymentioning

confidence: 99%

The strangest proton?

et al. 2020

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We present an improved determination of the strange quark and antiquark parton distribution functions of the proton by means of a global QCD analysis that takes into account a comprehensive set of strangeness-sensitive measurements: charm-tagged cross sections for fixed-target neutrino–nucleus deep-inelastic scattering, and cross sections for inclusive gauge-boson production and W-boson production in association with light jets or charm quarks at hadron colliders. Our analysis is accurate to next-to-next-to-leading order in perturbative QCD where available, and specifically includes charm-quark mass corrections to neutrino–nucleus structure functions. We find that a good overall description of the input dataset can be achieved and that a strangeness moderately suppressed in comparison to the rest of the light sea quarks is strongly favored by the global analysis.

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Single top production in PDF fits

Cited by 22 publications

References 92 publications

Parton distributions from LHC, HERA, Tevatron and fixed target data: MSHT20 PDFs

Parton distributions from LHC, HERA, Tevatron and fixed target data: MSHT20 PDFs

Single-top-quark production in the t-channel at NNLO

The strangest proton?

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