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We present a methodology to streamline implementation of massive-quark radiative contributions in calculations with a variable number of active partons in proton-proton collisions. The methodology introduces and heavy-quark parton distribution functions (PDFs) to implement calculations in the Aivazis–Collins–Olness–Tung (ACOT) factorization scheme and its simplified realization in various processes up to the next-to-the-next-to-leading order in the QCD coupling strength. Interpolation tables for bottom-quark subtraction and residual distributions for CT18 NLO and NNLO PDF ensembles are provided in the common LHAPDF6 format. A numerical calculation of $Z$-boson production with at least one $b$jet at the Large Hadron Collider beyond the lowest order in QCD is considered for illustration purposes. Published by the American Physical Society2024 

We discuss the impact of eligible top-quark pair production differential cross-section measurements at the LHC with a collision energy of 13 TeV on the parton distribution functions (PDFs) of the proton as well as the impact of approximate next-to-next-to-next-to-leading order (aN3LO) QCD corrections combined with next-to-leading order (NLO) electroweak (EW) corrections on tt¯ observables. We illustrate the effects on the gluon PDF at large x from an optimal baseline selection of data in NNLO global fits, and show comparisons between the theory prediction for tt¯ total and differential cross sections at aN3LO QCD combined with NLO EW and recent measurements from the ATLAS and CMS collaborations at the LHC. 

We review recent studies by the CTEQ-TEA group toward the development of a new generation of precision parton distribution functions in the nucleon for advanced studies at the high-luminosity LHC and in other experiments. Among several ongoing e!orts, we examine sensitivity to the PDFs and mutual compatibility of new measurements in production of Drell-Yan pairs, top-quark pairs, and single-inclusive jets by the ATLAS, CMS, and LHCb collaborations in the LHC Runs 1 and 2. 

The future of collider physics is under investigation. With the High Luminosity LHC program lasting until the late 2030s, the next machine in the energy frontier is envisioned to appear in 30-40 years, which may be too far into the future to sustain the field. In this paper we explore the physics potential of an Upgraded Superconducting Super Collider (USSC). The Original Superconducting Super Collider (OSSC) was planned to operate at 20 TeV beam energy, and with improved magnet technology and/or longer tunnel, one may envision that it can be extended to 25-30 TeV beam energy. Given that the decision on the OSSC construction took place in Autumn 1988 and it was planned to start operation in the 1996-1999 period, an USSC can be constructed 10-15 years from construction and fill the gap between the end of HL-LHC and the future envisioned machines. While the main mission of the USSC will be to test the Standard Model and its electroweak and strongly interacting sectors, as a specific example we illustrate the invariant mass distribution at NNLO in QCD for a 5 TeV Z′ in the string derived Z′ model. 

Abstract We consider$$Z'$$ $Z^{\prime }$s in heterotic string derived models and study$$Z'$$ $Z^{\prime }$resonant production at the TeV scale at the Large Hadron Collider (LHC). We use various kinematic differential distributions for the Drell–Yan process at NNLO in QCD to explore the parameter space of such models and investigate$$Z'$$ $Z^{\prime }$couplings. In particular, we study the impact ofZ-$$Z'$$ $Z^{\prime }$kinetic-mixing interactions on forward-backward asymmetry ($$A_{FB}$$ $A_{\mathrm{FB}}$) and other distributions at the LHC. 

Abstract We investigate the impact of sterile neutrinos on the decay rate of extra$$Z'$$ $Z^{\prime }$s with mass in the TeV range in heterotic string derived models. We explore the impact of sterile neutrinos on the current$$Z'$$ $Z^{\prime }$mass exclusion limits at the LHC, and how these bounds change when the parameter space of this specific class of models is modified. 

We discuss the impact of heavy-flavor production measurements in semi-inclusive deep inelastic scattering at HERA on the CTEQ-TEA PDFs.In particular, we study the impact of the latest charm and bottom production measurements from the H1 and ZEUS collaborations on the gluon, and the interplay of these measurements with the data ensemble of the recent CT18 global QCD analysis.