26-30 July 2021
Europe/Berlin timezone

Photon PDF and Impact from heavy flavors in the CT18 global analysis

26 Jul 2021, 16:45


Parallel session talk QCD and Hadronic Physics T06: QCD and Hadronic Physics


Keping Xie (Pitt Pacc)


Building upon the most recent CT18 global fit, we present:
1) A new calculation of the photon content of proton based on an application of the LUXqed formalism.
2) The impact of heavy-flavor production data on the CT18 PDFs family.

CT18 Photon PDF: We explore two principal variations of the LUXqed ansatz. In one approach which we designate CT18lux, the photon PDF is calculated directly using the LUXqed formula for all scales, $Q$. In an alternative realization, CT18qed, we instead initialize the photon PDF in terms of the LUXqed formulation at a lower scale, $Q\approx Q_0$, and evolve to higher scales with a combined QED kernel at ${\cal O}(\alpha)$, ${\cal O}(\alpha \alpha_s)$ and ${\cal O}(\alpha^2)$. Phenomenological implications of these photon PDFs at the LHC are discussed.

Heavy flavors in CT18: We discuss the impact of heavy-flavor production data on the CT18 PDFs family. In particular, we discuss the impact on the CT18 global analysis of the latest charm and bottom production measurements from the H1 and ZEUS collaborations and the differential top-quark pair production cross section measurements from CMS and ATLAS. We discuss tensions and interplays between heavy-quark observables in the global fit and the different pulls on the CT18 gluon.

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