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| 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) ; | ||
| Figures | |
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Figure 1:
Examples of $ \rm D^{0} $ meson candidate invariant mass distributions in 0nXn events. (Left) Invariant mass distribution for $ \rm D^{0} $ mesons with 2 $ < p_{\mathrm{T}} < $ 5 GeV and $ -$1 $ < y < $ 1. (Right) Invariant mass distribution of $ \rm D^{0} $ mesons with 5 $ < p_{\mathrm{T}} < $ 8 GeV and 0 $ < y < $ 1. The fit template is described in the text. |
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Figure 1-a:
Examples of $ \rm D^{0} $ meson candidate invariant mass distributions in 0nXn events. (Left) Invariant mass distribution for $ \rm D^{0} $ mesons with 2 $ < p_{\mathrm{T}} < $ 5 GeV and $ -$1 $ < y < $ 1. (Right) Invariant mass distribution of $ \rm D^{0} $ mesons with 5 $ < p_{\mathrm{T}} < $ 8 GeV and 0 $ < y < $ 1. The fit template is described in the text. |
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Figure 1-b:
Examples of $ \rm D^{0} $ meson candidate invariant mass distributions in 0nXn events. (Left) Invariant mass distribution for $ \rm D^{0} $ mesons with 2 $ < p_{\mathrm{T}} < $ 5 GeV and $ -$1 $ < y < $ 1. (Right) Invariant mass distribution of $ \rm D^{0} $ mesons with 5 $ < p_{\mathrm{T}} < $ 8 GeV and 0 $ < y < $ 1. The fit template is described in the text. |
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Figure 2:
Cross section of $ \rm D^{0} $ meson production for $ \gamma $N (Xn0n combined with rapidity reflected 0nXn) events compared with the FONLL predictions with EPSS21 nuclear PDF parametrization [37]. The black boxes represent the systematic uncertainty on the data. The light blue solid band indicates the scale uncertainty on the FONLL calculation, while the hatched dark blue band represents the nPDF uncertainty. The 5.05% global uncertainty is the combined uncertainty due to the integrated luminosity and $ \rm D^{0} $ branching ratio. |
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Figure 2-a:
Cross section of $ \rm D^{0} $ meson production for $ \gamma $N (Xn0n combined with rapidity reflected 0nXn) events compared with the FONLL predictions with EPSS21 nuclear PDF parametrization [37]. The black boxes represent the systematic uncertainty on the data. The light blue solid band indicates the scale uncertainty on the FONLL calculation, while the hatched dark blue band represents the nPDF uncertainty. The 5.05% global uncertainty is the combined uncertainty due to the integrated luminosity and $ \rm D^{0} $ branching ratio. |
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Figure 2-b:
Cross section of $ \rm D^{0} $ meson production for $ \gamma $N (Xn0n combined with rapidity reflected 0nXn) events compared with the FONLL predictions with EPSS21 nuclear PDF parametrization [37]. The black boxes represent the systematic uncertainty on the data. The light blue solid band indicates the scale uncertainty on the FONLL calculation, while the hatched dark blue band represents the nPDF uncertainty. The 5.05% global uncertainty is the combined uncertainty due to the integrated luminosity and $ \rm D^{0} $ branching ratio. |
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Figure 2-c:
Cross section of $ \rm D^{0} $ meson production for $ \gamma $N (Xn0n combined with rapidity reflected 0nXn) events compared with the FONLL predictions with EPSS21 nuclear PDF parametrization [37]. The black boxes represent the systematic uncertainty on the data. The light blue solid band indicates the scale uncertainty on the FONLL calculation, while the hatched dark blue band represents the nPDF uncertainty. The 5.05% global uncertainty is the combined uncertainty due to the integrated luminosity and $ \rm D^{0} $ branching ratio. |
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Figure 3:
Multiplicity of charged tracks satisfying a high-purity criteria for events passing all selections, with at least one selected $ \rm D^{0} $ meson with 2 $ < p_{\mathrm{T}} < $ 12 GeV. Events passing (failing) the rapidity gap conditions are shown in red (blue). |
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Figure 4:
(Left) Correlation between the ZDC energies in the ZDC plus and minus detectors measured for empty-bunch-crossing (EBX) events. (Right) Distribution of the signals for the two ZDCs. The ZDC energies are here obtained subtracts for the out of time pileup (OOTPU) contribution by subtracting from the time slice containing the signal of interest (TS2) the ZDC energy sum in the preceding time slide (TS1). |
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Figure 4-a:
(Left) Correlation between the ZDC energies in the ZDC plus and minus detectors measured for empty-bunch-crossing (EBX) events. (Right) Distribution of the signals for the two ZDCs. The ZDC energies are here obtained subtracts for the out of time pileup (OOTPU) contribution by subtracting from the time slice containing the signal of interest (TS2) the ZDC energy sum in the preceding time slide (TS1). |
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Figure 4-b:
(Left) Correlation between the ZDC energies in the ZDC plus and minus detectors measured for empty-bunch-crossing (EBX) events. (Right) Distribution of the signals for the two ZDCs. The ZDC energies are here obtained subtracts for the out of time pileup (OOTPU) contribution by subtracting from the time slice containing the signal of interest (TS2) the ZDC energy sum in the preceding time slide (TS1). |
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Figure 5:
(Left) $ \mathrm{E}^{\text{max}} $ distributions obtained in empty-bunch-crossing (EBX) events for both HF Plus and Minus. (Right) Cumulative distribution of $ \mathrm{E}^{\text{max}} $ in EBX events for both HF plus and minus. An energy threshold of 9.2 (8.6) GeV is considered for the rapidity gap requirement on the HF detector located at positive (negative) pseudorapidity. |
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Figure 5-a:
(Left) $ \mathrm{E}^{\text{max}} $ distributions obtained in empty-bunch-crossing (EBX) events for both HF Plus and Minus. (Right) Cumulative distribution of $ \mathrm{E}^{\text{max}} $ in EBX events for both HF plus and minus. An energy threshold of 9.2 (8.6) GeV is considered for the rapidity gap requirement on the HF detector located at positive (negative) pseudorapidity. |
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Figure 5-b:
(Left) $ \mathrm{E}^{\text{max}} $ distributions obtained in empty-bunch-crossing (EBX) events for both HF Plus and Minus. (Right) Cumulative distribution of $ \mathrm{E}^{\text{max}} $ in EBX events for both HF plus and minus. An energy threshold of 9.2 (8.6) GeV is considered for the rapidity gap requirement on the HF detector located at positive (negative) pseudorapidity. |
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Figure 6:
Charged-hadron multiplicity $ p_{\mathrm{T}} $ for high-purity tracks with $ |\eta| < $2.4 in events with a $ \rm D^{0} $ mesons in different $ p_{\mathrm{T}} $ and rapidity intervals. The distributions obtained in Pythia+EvGen simulations are shown in blue. CMS data, corrected on an event-by-event basis for the trigger selection efficiency, are shown in red. |
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Figure 6-a:
Charged-hadron multiplicity $ p_{\mathrm{T}} $ for high-purity tracks with $ |\eta| < $2.4 in events with a $ \rm D^{0} $ mesons in different $ p_{\mathrm{T}} $ and rapidity intervals. The distributions obtained in Pythia+EvGen simulations are shown in blue. CMS data, corrected on an event-by-event basis for the trigger selection efficiency, are shown in red. |
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Figure 6-b:
Charged-hadron multiplicity $ p_{\mathrm{T}} $ for high-purity tracks with $ |\eta| < $2.4 in events with a $ \rm D^{0} $ mesons in different $ p_{\mathrm{T}} $ and rapidity intervals. The distributions obtained in Pythia+EvGen simulations are shown in blue. CMS data, corrected on an event-by-event basis for the trigger selection efficiency, are shown in red. |
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Figure 7:
Transverse momentum $ p_{\mathrm{T}} $ for high-purity tracks with $ |\eta| < $2.4 in events, with a $ \rm D^{0} $ mesons in different $ p_{\mathrm{T}} $ and rapidity intervals. The distributions obtained in Pythia+EvGen simulations are shown in blue. CMS data, corrected on an event-by-event basis for the trigger selection efficiency, are shown in red. |
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Figure 7-a:
Transverse momentum $ p_{\mathrm{T}} $ for high-purity tracks with $ |\eta| < $2.4 in events, with a $ \rm D^{0} $ mesons in different $ p_{\mathrm{T}} $ and rapidity intervals. The distributions obtained in Pythia+EvGen simulations are shown in blue. CMS data, corrected on an event-by-event basis for the trigger selection efficiency, are shown in red. |
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Figure 7-b:
Transverse momentum $ p_{\mathrm{T}} $ for high-purity tracks with $ |\eta| < $2.4 in events, with a $ \rm D^{0} $ mesons in different $ p_{\mathrm{T}} $ and rapidity intervals. The distributions obtained in Pythia+EvGen simulations are shown in blue. CMS data, corrected on an event-by-event basis for the trigger selection efficiency, are shown in red. |
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Figure 8:
Pseudorapidity distribution of charged tracks with $ p_{\mathrm{T}} > $ 0.5 GeV for events passing all event selections, for events with a $ \rm D^{0} $ meson in different $ p_{\mathrm{T}} $ and rapidity intervals. The distributions obtained in Pythia+EvGen simulations are shown in blue. CMS data, corrected on an event-by-event basis for the trigger selection efficiency, are shown in red. |
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Figure 8-a:
Pseudorapidity distribution of charged tracks with $ p_{\mathrm{T}} > $ 0.5 GeV for events passing all event selections, for events with a $ \rm D^{0} $ meson in different $ p_{\mathrm{T}} $ and rapidity intervals. The distributions obtained in Pythia+EvGen simulations are shown in blue. CMS data, corrected on an event-by-event basis for the trigger selection efficiency, are shown in red. |
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Figure 8-b:
Pseudorapidity distribution of charged tracks with $ p_{\mathrm{T}} > $ 0.5 GeV for events passing all event selections, for events with a $ \rm D^{0} $ meson in different $ p_{\mathrm{T}} $ and rapidity intervals. The distributions obtained in Pythia+EvGen simulations are shown in blue. CMS data, corrected on an event-by-event basis for the trigger selection efficiency, are shown in red. |
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Figure 9:
$ \rm D^{0} $ meson candidate invariant mass distributions in 0nXn N$ \gamma $ events in UPC PbPb collisions at 5.36 TeV. The $ \rm D^{0} $ meson candidates are selected for $ p_{\mathrm{T}} $ in the interval 5-8 GeV, covering rapidities of $-$2 $ < y < $ $-$1, $-$1 $ < y < $ 0, and 1 $ < y < $ 2. Fit template includes exponential modeling of combinatoric background, double-Gaussian modeling of signal and single-Gaussian modeling of swapped components of $ \rm D^{0} $ meson mass peak, and Crystal Ball modeling of K$ ^{+} $K$ ^{-} $ and $ \pi^{+}\pi^{-} $ mass peaks. |
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Figure 9-a:
$ \rm D^{0} $ meson candidate invariant mass distributions in 0nXn N$ \gamma $ events in UPC PbPb collisions at 5.36 TeV. The $ \rm D^{0} $ meson candidates are selected for $ p_{\mathrm{T}} $ in the interval 5-8 GeV, covering rapidities of $-$2 $ < y < $ $-$1, $-$1 $ < y < $ 0, and 1 $ < y < $ 2. Fit template includes exponential modeling of combinatoric background, double-Gaussian modeling of signal and single-Gaussian modeling of swapped components of $ \rm D^{0} $ meson mass peak, and Crystal Ball modeling of K$ ^{+} $K$ ^{-} $ and $ \pi^{+}\pi^{-} $ mass peaks. |
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Figure 9-b:
$ \rm D^{0} $ meson candidate invariant mass distributions in 0nXn N$ \gamma $ events in UPC PbPb collisions at 5.36 TeV. The $ \rm D^{0} $ meson candidates are selected for $ p_{\mathrm{T}} $ in the interval 5-8 GeV, covering rapidities of $-$2 $ < y < $ $-$1, $-$1 $ < y < $ 0, and 1 $ < y < $ 2. Fit template includes exponential modeling of combinatoric background, double-Gaussian modeling of signal and single-Gaussian modeling of swapped components of $ \rm D^{0} $ meson mass peak, and Crystal Ball modeling of K$ ^{+} $K$ ^{-} $ and $ \pi^{+}\pi^{-} $ mass peaks. |
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Figure 9-c:
$ \rm D^{0} $ meson candidate invariant mass distributions in 0nXn N$ \gamma $ events in UPC PbPb collisions at 5.36 TeV. The $ \rm D^{0} $ meson candidates are selected for $ p_{\mathrm{T}} $ in the interval 5-8 GeV, covering rapidities of $-$2 $ < y < $ $-$1, $-$1 $ < y < $ 0, and 1 $ < y < $ 2. Fit template includes exponential modeling of combinatoric background, double-Gaussian modeling of signal and single-Gaussian modeling of swapped components of $ \rm D^{0} $ meson mass peak, and Crystal Ball modeling of K$ ^{+} $K$ ^{-} $ and $ \pi^{+}\pi^{-} $ mass peaks. |
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Figure 10:
$ \rm D^{0} $ meson candidate invariant mass distributions in 0nXn $ \gamma $N events in UPC PbPb collisions at 5.36 TeV. The $ \rm D^{0} $ meson candidates are selected for $ p_{\mathrm{T}} $ in the interval 8-12 GeV, covering rapidities of $-$2 $ < y < $ $-$1, $-$1 $ < y < $ 0, 0 $ < y < $ 1, and 1 $ < y < $ 2. Fit template includes exponential modeling of combinatoric background, double-Gaussian modeling of signal and single-Gaussian modeling of swapped components of $ \rm D^{0} $ meson mass peak, and Crystal Ball modeling of K$ ^{+} $K$ ^{-} $ and $ \pi^{+}\pi^{-} $ mass peaks. |
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Figure 10-a:
$ \rm D^{0} $ meson candidate invariant mass distributions in 0nXn $ \gamma $N events in UPC PbPb collisions at 5.36 TeV. The $ \rm D^{0} $ meson candidates are selected for $ p_{\mathrm{T}} $ in the interval 8-12 GeV, covering rapidities of $-$2 $ < y < $ $-$1, $-$1 $ < y < $ 0, 0 $ < y < $ 1, and 1 $ < y < $ 2. Fit template includes exponential modeling of combinatoric background, double-Gaussian modeling of signal and single-Gaussian modeling of swapped components of $ \rm D^{0} $ meson mass peak, and Crystal Ball modeling of K$ ^{+} $K$ ^{-} $ and $ \pi^{+}\pi^{-} $ mass peaks. |
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Figure 10-b:
$ \rm D^{0} $ meson candidate invariant mass distributions in 0nXn $ \gamma $N events in UPC PbPb collisions at 5.36 TeV. The $ \rm D^{0} $ meson candidates are selected for $ p_{\mathrm{T}} $ in the interval 8-12 GeV, covering rapidities of $-$2 $ < y < $ $-$1, $-$1 $ < y < $ 0, 0 $ < y < $ 1, and 1 $ < y < $ 2. Fit template includes exponential modeling of combinatoric background, double-Gaussian modeling of signal and single-Gaussian modeling of swapped components of $ \rm D^{0} $ meson mass peak, and Crystal Ball modeling of K$ ^{+} $K$ ^{-} $ and $ \pi^{+}\pi^{-} $ mass peaks. |
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Figure 10-c:
$ \rm D^{0} $ meson candidate invariant mass distributions in 0nXn $ \gamma $N events in UPC PbPb collisions at 5.36 TeV. The $ \rm D^{0} $ meson candidates are selected for $ p_{\mathrm{T}} $ in the interval 8-12 GeV, covering rapidities of $-$2 $ < y < $ $-$1, $-$1 $ < y < $ 0, 0 $ < y < $ 1, and 1 $ < y < $ 2. Fit template includes exponential modeling of combinatoric background, double-Gaussian modeling of signal and single-Gaussian modeling of swapped components of $ \rm D^{0} $ meson mass peak, and Crystal Ball modeling of K$ ^{+} $K$ ^{-} $ and $ \pi^{+}\pi^{-} $ mass peaks. |
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Figure 10-d:
$ \rm D^{0} $ meson candidate invariant mass distributions in 0nXn $ \gamma $N events in UPC PbPb collisions at 5.36 TeV. The $ \rm D^{0} $ meson candidates are selected for $ p_{\mathrm{T}} $ in the interval 8-12 GeV, covering rapidities of $-$2 $ < y < $ $-$1, $-$1 $ < y < $ 0, 0 $ < y < $ 1, and 1 $ < y < $ 2. Fit template includes exponential modeling of combinatoric background, double-Gaussian modeling of signal and single-Gaussian modeling of swapped components of $ \rm D^{0} $ meson mass peak, and Crystal Ball modeling of K$ ^{+} $K$ ^{-} $ and $ \pi^{+}\pi^{-} $ mass peaks. |
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Figure 11:
Trigger efficiency corrections (1 $ /\varepsilon_\mathrm{trig} $) as a function of $ \rm D^{0} $ rapidity for $ \rm D^{0} $ with 5$ < p_{\mathrm{T}} < $ 8 GeV (left) and 8$ < p_{\mathrm{T}} < $ 12 GeV (right). |
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Figure 11-a:
Trigger efficiency corrections (1 $ /\varepsilon_\mathrm{trig} $) as a function of $ \rm D^{0} $ rapidity for $ \rm D^{0} $ with 5$ < p_{\mathrm{T}} < $ 8 GeV (left) and 8$ < p_{\mathrm{T}} < $ 12 GeV (right). |
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Figure 11-b:
Trigger efficiency corrections (1 $ /\varepsilon_\mathrm{trig} $) as a function of $ \rm D^{0} $ rapidity for $ \rm D^{0} $ with 5$ < p_{\mathrm{T}} < $ 8 GeV (left) and 8$ < p_{\mathrm{T}} < $ 12 GeV (right). |
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Figure 12:
Trigger efficiency as a function of $ \rm D^{0} $ rapidity for $ \rm D^{0} $ with 5$ < p_{\mathrm{T}} < $ 8 GeV (left) and 8$ < p_{\mathrm{T}} < $ 12 GeV (right). |
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Figure 12-a:
Trigger efficiency as a function of $ \rm D^{0} $ rapidity for $ \rm D^{0} $ with 5$ < p_{\mathrm{T}} < $ 8 GeV (left) and 8$ < p_{\mathrm{T}} < $ 12 GeV (right). |
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Figure 12-b:
Trigger efficiency as a function of $ \rm D^{0} $ rapidity for $ \rm D^{0} $ with 5$ < p_{\mathrm{T}} < $ 8 GeV (left) and 8$ < p_{\mathrm{T}} < $ 12 GeV (right). |
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Figure 13:
Reconstruction and selection efficiencies for prompt and non-prompt $ \rm D^{0} $ mesons as a function of the $ \rm D^{0} $ rapidity, in intervals of $ \rm D^{0} p_{\mathrm{T}} $. Prompt $ \rm D^{0} $ mesons, shown in red, originate from c-quarks, while non-prompt $ \rm D^{0} $ mesons, shown in blue originate from b-quarks. Inclusive (nominal) efficiencies are included in black for reference. |
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Figure 14:
Examples of template fits for the extraction of the prompt fraction in data in intervals of $ \rm D^{0} p_{\mathrm{T}} $ and y. (Left) Distance-of-closest-approach (DCA) distribution for $ \rm D^{0} $ in the binning of 2 $ < p_{\mathrm{T}} < $ 5 GeV and $-$1 $ < y < $ 1. (Right) DCA distribution for $ \rm D^{0} $ in the binning of 5 $ < p_{\mathrm{T}} < $ 8 GeV and $-$1 $ < y < $ 0. In both panels, data and MC distributions are plotted with templates for prompt and non-prompt distributions overlaid |
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Figure 14-a:
Examples of template fits for the extraction of the prompt fraction in data in intervals of $ \rm D^{0} p_{\mathrm{T}} $ and y. (Left) Distance-of-closest-approach (DCA) distribution for $ \rm D^{0} $ in the binning of 2 $ < p_{\mathrm{T}} < $ 5 GeV and $-$1 $ < y < $ 1. (Right) DCA distribution for $ \rm D^{0} $ in the binning of 5 $ < p_{\mathrm{T}} < $ 8 GeV and $-$1 $ < y < $ 0. In both panels, data and MC distributions are plotted with templates for prompt and non-prompt distributions overlaid |
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Figure 14-b:
Examples of template fits for the extraction of the prompt fraction in data in intervals of $ \rm D^{0} p_{\mathrm{T}} $ and y. (Left) Distance-of-closest-approach (DCA) distribution for $ \rm D^{0} $ in the binning of 2 $ < p_{\mathrm{T}} < $ 5 GeV and $-$1 $ < y < $ 1. (Right) DCA distribution for $ \rm D^{0} $ in the binning of 5 $ < p_{\mathrm{T}} < $ 8 GeV and $-$1 $ < y < $ 0. In both panels, data and MC distributions are plotted with templates for prompt and non-prompt distributions overlaid |
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Figure 15:
Fully corrected double-differential cross sections for the $ \gamma $+N (left) and N+$ \gamma $ (right) production of $ \rm D^{0} $. Systematic uncertainties are represented as rectangular boxes around the data points. The 5.05% global uncertainty is the combined uncertainty of the integrated luminosity and $ \rm D^{0} $ branching ratio. |
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Figure 15-a:
Fully corrected double-differential cross sections for the $ \gamma $+N (left) and N+$ \gamma $ (right) production of $ \rm D^{0} $. Systematic uncertainties are represented as rectangular boxes around the data points. The 5.05% global uncertainty is the combined uncertainty of the integrated luminosity and $ \rm D^{0} $ branching ratio. |
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Figure 15-b:
Fully corrected double-differential cross sections for the $ \gamma $+N (left) and N+$ \gamma $ (right) production of $ \rm D^{0} $. Systematic uncertainties are represented as rectangular boxes around the data points. The 5.05% global uncertainty is the combined uncertainty of the integrated luminosity and $ \rm D^{0} $ branching ratio. |
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Figure 16:
Fully corrected cross section for the $ \gamma $+N combined with the reflected N+$ \gamma $ production of $ \rm D^{0} $ as a function of $ \rm D^{0} p_{\mathrm{T}} $ and rapidity. Systematic uncertainties are represented as rectangular boxes around the data points. The 5.05% global uncertainty is the combined uncertainty of the integrated luminosity and $ \rm D^{0} $ branching ratio. |
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Figure 17:
Cross section of $ \rm D^{0} $ meson production for the various $ p_{\mathrm{T}} $ bins of the analysis. Systematic uncertainties are represented as rectangular boxes around the data points. The 5.05% global uncertainty is the combined uncertainty of the integrated luminosity and $ \rm D^{0} $ branching ratio. |
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Figure 17-a:
Cross section of $ \rm D^{0} $ meson production for the various $ p_{\mathrm{T}} $ bins of the analysis. Systematic uncertainties are represented as rectangular boxes around the data points. The 5.05% global uncertainty is the combined uncertainty of the integrated luminosity and $ \rm D^{0} $ branching ratio. |
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Figure 17-b:
Cross section of $ \rm D^{0} $ meson production for the various $ p_{\mathrm{T}} $ bins of the analysis. Systematic uncertainties are represented as rectangular boxes around the data points. The 5.05% global uncertainty is the combined uncertainty of the integrated luminosity and $ \rm D^{0} $ branching ratio. |
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Figure 17-c:
Cross section of $ \rm D^{0} $ meson production for the various $ p_{\mathrm{T}} $ bins of the analysis. Systematic uncertainties are represented as rectangular boxes around the data points. The 5.05% global uncertainty is the combined uncertainty of the integrated luminosity and $ \rm D^{0} $ branching ratio. |
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Figure 18:
Cross section of $ \rm D^{0} $ meson production compared with the theoretical predictions provided by FONLL with proton CT18 PDF parametrization. Each plot corresponds to a different $ p_{\mathrm{T}} $ bin: 2-5 GeV (top left), 5-8 GeV (top right), and 8-12 GeV (bottom). Points are plotted as a function of $ \rm D^{0} y $. A ratio of data over theory is provided in the bottom panel. Theory uncertainty is represented by shaded band, while experimental uncertainty is represented by the black box. The 5.05% global uncertainty is the combined uncertainty of the integrated luminosity and $ \rm D^{0} $ branching ratio. |
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Figure 18-a:
Cross section of $ \rm D^{0} $ meson production compared with the theoretical predictions provided by FONLL with proton CT18 PDF parametrization. Each plot corresponds to a different $ p_{\mathrm{T}} $ bin: 2-5 GeV (top left), 5-8 GeV (top right), and 8-12 GeV (bottom). Points are plotted as a function of $ \rm D^{0} y $. A ratio of data over theory is provided in the bottom panel. Theory uncertainty is represented by shaded band, while experimental uncertainty is represented by the black box. The 5.05% global uncertainty is the combined uncertainty of the integrated luminosity and $ \rm D^{0} $ branching ratio. |
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Figure 18-b:
Cross section of $ \rm D^{0} $ meson production compared with the theoretical predictions provided by FONLL with proton CT18 PDF parametrization. Each plot corresponds to a different $ p_{\mathrm{T}} $ bin: 2-5 GeV (top left), 5-8 GeV (top right), and 8-12 GeV (bottom). Points are plotted as a function of $ \rm D^{0} y $. A ratio of data over theory is provided in the bottom panel. Theory uncertainty is represented by shaded band, while experimental uncertainty is represented by the black box. The 5.05% global uncertainty is the combined uncertainty of the integrated luminosity and $ \rm D^{0} $ branching ratio. |
png pdf |
Figure 18-c:
Cross section of $ \rm D^{0} $ meson production compared with the theoretical predictions provided by FONLL with proton CT18 PDF parametrization. Each plot corresponds to a different $ p_{\mathrm{T}} $ bin: 2-5 GeV (top left), 5-8 GeV (top right), and 8-12 GeV (bottom). Points are plotted as a function of $ \rm D^{0} y $. A ratio of data over theory is provided in the bottom panel. Theory uncertainty is represented by shaded band, while experimental uncertainty is represented by the black box. The 5.05% global uncertainty is the combined uncertainty of the integrated luminosity and $ \rm D^{0} $ branching ratio. |
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Figure 19:
No-nuclear-breakup probability as a function of $ \rm D^{0} p_{\mathrm{T}} $ and $ y $, estimated using Pythia 8 and Starlight simulations. The effective photon flux parametrization is taken from Ref. [49]. |
| Summary |
| This note presents the first cross section measurement of the production of inclusive (prompt and nonprompt) $ \rm D^{0} $ mesons as a function of their transverse momentum $ p_{\mathrm{T}} $ and rapidity $ y $ in ultraperipheral heavy-ion collisions. The measurement uses lead-lead collision data collected by the CMS experiment at a collision energy of $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.36 TeV at the LHC. The events of interest are selected using the zero degree calorimeters (ZDC) of the CMS experiment, which measure the forward neutrons produced from the nuclear breakup. Such events are selected such that exactly one of the outgoing lead ion remains intact (no neutron signal in the ZDC) and the other lead ion breaks up (neutron signal in the other ZDC), leading to a ``0nXn'' topology. In addition, a large rapidity interval devoid of particle activity in the direction of the intact lead ion is required to increase the fraction of photonuclear interactions in the sample, $ \gamma^* N \to \rm D^{0} + $ X. The measured $ \rm D^{0} $ meson yields are corrected for detector acceptance and efficiency. The measurement is compared to theoretical calculations at next-to-leading order using recent parametrizations of nuclear parton distribution functions. The predictions are in good agreement with the data within the experimental and theoretical uncertainties. This measurement provides new experimental constraints on nuclear matter with heavy-quark observables over a large range of $ x $ and $ Q^{2} $, and opens the way for a vast experimental program exploiting fully-reconstructed heavy-flavor hadrons and heavy-flavor jets in ultraperipheral heavy-ion collisions at the LHC. |
| References | ||||
| 1 | Y. L. Dokshitzer, V. A. Khoze, A. H. Mueller, and S. I. Troian | Basics of perturbative QCD | ||
| 2 | V. N. Gribov and L. N. Lipatov | Deep inelastic ep scattering in perturbation theory | Sov. J. Nucl. Phys. 15 (1972) 438 | |
| 3 | G. Altarelli and G. Parisi | Asymptotic freedom in parton language | NPB 126 (1977) 298 | |
| 4 | Y. L. Dokshitzer | Calculation of the structure functions for deep inelastic scattering and e$ ^{+} $ e$ ^{-} $ annihilation by perturbation theory in quantum chromodynamics | Sov. Phys. JETP 46 (1977) 641 | |
| 5 | I. I. Balitsky and L. N. Lipatov | The Pomeranchuk singularity in quantum chromodynamics | Sov. J. Nucl. Phys. 28 (1978) 822 | |
| 6 | L. N. Lipatov | The bare pomeron in quantum chromodynamics | Sov. Phys. JETP 63 (1986) 904 | |
| 7 | J. Jalilian-Marian, A. Kovner, A. Leonidov, and H. Weigert | The BFKL equation from the Wilson renormalization group | NPB 504 (1997) 415 | hep-ph/9701284 |
| 8 | J. Jalilian-Marian, A. Kovner, A. Leonidov, and H. Weigert | Wilson renormalization group for low x physics: Towards the high density regime | PRD 59 (1998) 014014 | |
| 9 | J. Jalilian-Marian, A. Kovner, L. McLerran, and H. Weigert | Intrinsic glue distribution at very small $ x $ | PRD 55 (1997) 5414 | |
| 10 | H. Weigert | Unitarity at small Bjorken x | --860, 2002 Nucl. Phys. A 703 (2002) 823 |
hep-ph/0004044 |
| 11 | A. H. Mueller | A simple derivation of the JIMWLK equation | --248, 2001 PLB 523 (2001) 243 |
hep-ph/0110169 |
| 12 | I. Balitsky | Operator expansion for high-energy scattering | no.~1, 99, 1996 Nuclear Physics B 463 (1996) |
|
| 13 | F. Gelis | Color glass condensate and glasma | Int. J. Mod. Phys. A 28 (2013) 1330001 | 1211.3327 |
| 14 | L. D. McLerran and R. Venugopalan | Gluon distribution functions for very large nuclei at small transverse momentum | --3355, 1994 PRD 49 (1994) 3352 |
hep-ph/9311205 |
| 15 | E. Iancu and R. Venugopalan | The color glass condensate and high-energy scattering in QCD | in Quark-Gluon Plasma 4, R.~C. Hwa and X.-N. Wang, eds, 2003 link |
hep-ph/0303204 |
| 16 | H1, ZEUS Collaboration | Combination of measurements of inclusive deep inelastic $ {e^{\pm }p} $ scattering cross sections and QCD analysis of HERA data | no.~12, 580, 2015 EPJC 75 (2015) |
1506.06042 |
| 17 | H1, ZEUS Collaboration | Combination and QCD analysis of charm production cross section measurements in deep inelastic ep scattering at HERA | no.~2, 2311, 2013 EPJC 73 (2013) |
1211.1182 |
| 18 | NNPDF Collaboration | Nuclear parton distributions from lepton-nucleus scattering and the impact of an electron-ion collider | no.~6, 471, 2019 EPJC 79 (2019) |
1904.00018 |
| 19 | ALICE Collaboration | D-meson production in pPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}}= $ 5.02 TeV and in pp collisions at $ \sqrt{s}= $ 7 TeV | no.~5, 054908, 2016 Phys. Rev. C 94 (2016) |
1605.07569 |
| 20 | CMS Collaboration | Study of B meson production in pPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV using exclusive hadronic decays | no.~3, 032301, 2016 PRL 116 (2016) |
CMS-HIN-14-004 1508.06678 |
| 21 | LHCb Collaboration | Study of prompt $ \rm D^{0} $ meson production in pPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}}= $ 5 TeV | JHEP 10 (2017) 090 | 1707.02750 |
| 22 | LHCb Collaboration | Observation of strangeness enhancement with charmed mesons in high-multiplicity $ p\mathrm{Pb} $ collisions at $ \sqrt {s_{\mathrm{NN}}}=8.16\, $TeV | PRD 110 (2023) L031105 | 2311.08490 |
| 23 | M. Strikman, R. Vogt, and S. N. White | Probing small $ x $ parton densities in ultraperipheral AA and pA collisions at the LHC | PRL 96 (2006) 082001 | hep-ph/0508296 |
| 24 | CMS Collaboration | Coherent $ J/\psi $ photoproduction in ultraperipheral PbPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 2.76 TeV with the CMS experiment | PLB 772 (2017) 489 | CMS-HIN-12-009 1605.06966 |
| 25 | ALICE Collaboration | Coherent $ J/\psi $ and $ \psi' $ photoproduction at midrapidity in ultra-peripheral PbPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV | no.~8, 712, 2021 EPJC 81 (2021) |
2101.04577 |
| 26 | LHCb Collaboration | Study of exclusive photoproduction of charmonium in ultra-peripheral lead-lead collisions | JHEP 06 (2023) 146 | 2206.08221 |
| 27 | ALICE Collaboration | Energy dependence of coherent photonuclear production of J/\ensuremath\psi mesons in ultra-peripheral Pb-Pb collisions at $ \sqrt{{\textrm{s}}_{\textrm{NN}}} $ = 5.02 TeV | JHEP 10 (2023) 119 | 2305.19060 |
| 28 | CMS Collaboration | Probing small Bjorken-$ x $ nuclear gluonic structure via coherent $ J/\psi $ photoproduction in ultraperipheral PbPb Collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV | no.~26, 262301, 2023 PRL 131 (2023) |
CMS-HIN-22-002 2303.16984 |
| 29 | ATLAS Collaboration | Photonuclear jet production in ultraperipheral PbPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV with the ATLAS detector | ATLAS Conference Note ATLAS-CONF-2022-021, 2022 | |
| 30 | S. R. Klein, J. Nystrand, and R. Vogt | Heavy quark photoproduction in ultraperipheral heavy ion collisions | (Oct, ) 044906, 2002 Phys. Rev. C 6 (2002) 6 |
|
| 31 | CMS Collaboration | Particle-flow reconstruction and global event description with the CMS detector | no.~10, P3, 2017 JINST 12 (2017) |
CMS-PRF-14-001 1706.04965 |
| 32 | CMS Collaboration | The CMS trigger system | JINST 12 (2017) P01020 | CMS-TRG-12-001 1609.02366 |
| 33 | CMS Collaboration | The CMS experiment at the CERN LHC | JINST 3 (2008) S08004 | |
| 34 | CMS Collaboration | Performance of missing transverse momentum reconstruction in proton-proton collisions at $ \sqrt{s} = $ 13 TeV using the CMS detector | no.~07, P07004, 2019 JINST 14 (2019) |
CMS-JME-17-001 1903.06078 |
| 35 | C. Bierlich et al. | A comprehensive guide to the physics and usage of PYTHIA 8.3 | SciPost Phys. Codeb. 2022 (2022) 8 | 2203.11601 |
| 36 | F. Cornet, P. Jankowski, M. Krawczyk, and A. Lorca | New 5-flavor LO analysis and parametrization of parton distributions in the real photon | (Jul, ) 014010, 2003 PRD 6 (2003) 8 |
|
| 37 | K. J. Eskola, P. Paakkinen, H. Paukkunen, and C. A. Salgado | EPPS21: a global QCD analysis of nuclear PDFs | no.~5, 413, 2022 EPJC 82 (2022) |
2112.12462 |
| 38 | GEANT4 Collaboration | GEANT4 --- a simulation toolkit | NIM A 506 (2003) 250 | |
| 39 | D. J. Lange | The EVTGEN particle decay simulation package | NIM A 462 (2001) 152 | |
| 40 | E. Barberio, B. van Eijk, and Z. Was | PHOTOS: A universal Monte Carlo for QED radiative corrections in decays | Comput. Phys. Commun. 66 (1991) 115 | |
| 41 | Particle Data Group Collaboration | Review of particle physics | no.~3, 030001, 2024 PRD 110 (2024) |
|
| 42 | CMS Collaboration | Nuclear modification factor of D$ ^0 $ mesons in PbPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV | PLB 782 (2018) 474 | CMS-HIN-16-001 1708.04962 |
| 43 | CMS Collaboration | Description and performance of track and primary-vertex reconstruction with the CMS tracker | JINST 9 (2014) P10009 | CMS-TRK-11-001 1405.6569 |
| 44 | ALICE Collaboration | Measurement of the cross section for electromagnetic dissociation with neutron emission in PbPb Collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 2.76 TeV | PRL 109 (2012) 252302 | 1203.2436 |
| 45 | CMS Collaboration | Search for rare charm decays into two muons | CMS Physics Analysis Summary, 2024 CMS-PAS-BPH-23-008 |
CMS-PAS-BPH-23-008 |
| 46 | M. Cacciari, M. Greco, and P. Nason | The $ p_{\mathrm{T}} $ spectrum in heavy-flavor hadroproduction. | JHEP 05 (1998) 007 | hep-ph/9803400 |
| 47 | E. Braaten, K. Cheung, S. Fleming, and T. C. Yuan | Perturbative qcd fragmentation functions as a model for heavy-quark fragmentation | (May, ) 4819--4829, 1995 PRD 5 (1995) 1 |
|
| 48 | M. Cacciari and P. Nason | Charm cross sections for the Tevatron Run 2 | JHEP 09 (2003) 006 | hep-ph/0306212 |
| 49 | K. J. Eskola et al. | Nuclear spatial resolution in near-encounter UPC dijet photoproduction | 2404.09731 | |
| 50 | S. R. Klein et al. | \textscSTARlight: A Monte Carlo simulation program for ultraperipheral collisions of relativistic ions | Comput. Phys. Commun. 212 (2017) 258 | 1607.03838 |
| 51 | A. J. Baltz, M. J. Rhoades-Brown, and J. Weneser | Heavy-ion partial beam lifetimes due to Coulomb induced processes | (Oct, ) 4233, 1996 Phys. Rev. E 5 (1996) 4 |
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