Abstract
We present the new parton distribution functions (PDFs) from the CTEQ-TEA collaboration, obtained using a wide variety of high-precision Large Hadron Collider (LHC) data, in addition to the combined HERA I+II deep-inelastic scattering data set, along with the data sets present in the CT14 global QCD analysis. New LHC measurements in single-inclusive jet production with the full rapidity coverage, as well as production of Drell-Yan pairs, top-quark pairs, and high-$p_T$ $Z$ bosons, are included to achieve the greatest sensitivity to the PDFs. The parton distributions are determined at NLO and NNLO, with each of these PDFs accompanied by error sets determined using the Hessian method. Fast PDF survey techniques, based on the Hessian representation and the Lagrange Multiplier method, are used to quantify the preference of each data set to quantities such as $\alpha_s(m_Z)$, and the gluon and strange quark distributions. We designate the main resulting PDF set as CT18. The ATLAS 7 TeV precision $W/Z$ data are not included in CT18, due to their tension with other data sets in the global fit. Alternate PDF sets are generated including the ATLAS precision 7 TeV $W/Z$ data (CT18A), a new scale choice for low-$x$ DIS data (CT18X), or all of the above with a slightly higher choice for the charm mass (CT18Z). Theoretical calculations of standard candle cross sections at the LHC (such as the $gg$ fusion Higgs boson cross section) are presented.
Highlights
ID 1⁄4 248) and other changes associated with CT18Z lead to a reconfiguration of the picture shown in Fig. 15 and to an increase in the best-fit value of mc, as we show in Fig. 71 and discuss in Appendix A
We have presented the CT18 family of parton distribution functions (PDFs), including the CT18Z, CT18A, and CT18X alternative fits
It represents the update following the release of the CT14 and CT14HERAII next-to-next-to-leading order (NNLO) distributions, the latter of which was prompted by the release of precision HERA I and II combined data after the publication of CT14
Summary
With an accumulated data sample of over 140 fb−1 at the 13 TeV run for both ATLAS and CMS collaborations, the Large Hadron Collider (LHC) has entered an era of. Measurements by LHCb often allow extrapolations into new kinematic regions not covered by the other experiments Some processes, such as tt production, allow for the measurement of multiple observables that provide similar information for the determination of PDFs. In addition to the PDFs themselves, we present relevant PDF luminosities and predictions with uncertainties for standard candle cross sections at the LHC. These comparisons will be of interest to a broad group of researchers who will use the PDFs for theoretical predictions at LHC experiments. Additional figures are included as Supplemental material [27]
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