CMS-PAS-HIN-24-003

CMS-PAS-HIN-24-003
Constraining nuclear parton dynamics with the first measurement of D$ ^0 $-photoproduction in ultraperipheral heavy-ion collisions at the LHC
CMS Collaboration
23 September 2024

Abstract: This note presents the first measurement of photonuclear D$ ^0 $ meson production in ultraperipheral heavy-ion collisions. The measurement uses 1.38 nb$ ^{-1} $ of data collected in lead-lead collisions by the CMS experiment at $ \sqrt {\smash [b]{s_{_{\mathrm {NN}}}}} = $ 5.36 TeV. Events where one of the colliding nuclei breaks up and the other remains intact (Xn0n) are selected by using the zero degree calorimeters and requiring the presence of a large rapidity gap in the photon-going direction. D$ ^0 $ mesons are reconstructed via the two-pronged D$ ^0 \rightarrow $ K$ ^{-} \pi^{+} $ decay channel as a function of their transverse momentum and rapidity for 2 $ < p_\mathrm{T} < $ 12 GeV and $-$2.0 $ < y < $ 2.0. The results are compared to perturbative quantum chromodynamics calculations at fixed-to-next-to-the-leading order which include the most recent parametrizations of the nuclear parton distribution functions of lead nuclei. This measurement provides new experimental constraints on nuclear matter with heavy-quark observables in a large region of $ x $ and $ Q^2 $ in the clean environment provided by photonuclear collisions.
Links: CDS record (PDF) ; CADI line (restricted) ; These preliminary results are superseded in this paper, Submitted to PRL. The superseded preliminary plots can be found here.

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