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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Photon-odderon interference in exclusive χ c charmonium production at the Electron-Ion Collider

Exclusive C = + 1 scalar, axial-vector, and tensor quarkonium production in high-energy electron-proton scattering requires a C -odd t -channel exchange of a photon or a three-gluon ladder. We derive the expressions for the corresponding amplitudes. The relative phase of the photon vs three-gluon exchange amplitudes is determined by the sign of the light-front matrix element of the eikonal color current operator d a b c J + a J + b J + c at moderate x , and is not affected by small- x QCD evolution. Model calculations predict constructive interference, which is particularly strong for momentum transfer | t | ∼ 1 GeV 2 where the cross section for χ c J production exceeds that for pure photon exchange by up to a factor of 4. Exclusive χ c J electroproduction at the high luminosity Electron-Ion Collider occurs with well measurable rates and measurements of these processes should find evidence for the perturbative odderon exchange. We also compute the total electroproduction cross section as a function of energy and provide first estimates of the number of χ c J events per month at the Electron-Ion Collider design luminosity. Published by the American Physical Society 2024

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Observation of the Charmonium Decay η c → γ γ in J / ψ → γ η c

Using ( 2712.4 ± 14.3 ) × 10 6 ψ ( 3686 ) events collected with the BESIII detector at the BEPCII collider, the decay η c → γ γ in J / ψ → γ η c is observed. We determine the product branching fraction B ( J / ψ → γ η c ) × B ( η c → γ γ ) = ( 5.23 ± 0.2 6 stat ± 0.3 0 syst ) × 10 − 6 . This result is consistent with the lattice QCD calculation ( 5.34 ± 0.16 ) × 10 − 6 from HPQCD in 2023. By using the world-average values of B ( J / ψ → γ η c ) and the total decay width of η c , the partial decay width Γ ( η c → γ γ ) is determined to be ( 11.30 ± 0.5 6 stat ± 0.6 6 syst ± 1.1 4 ref ) keV , which deviates from the corresponding world-average value by 3.4 σ . Published by the American Physical Society 2025

Ablikim, M.↗
DOE OSTI2018

Measurement of prompt and nonprompt charmonium suppression in $\text {PbPb}$ collisions at 5.02 $\,\text {Te}\text {V}$

The nuclear modification factors of ${\mathrm {J}/\psi }$ and $\psi \text {(2S)}$ mesons are measured in $\text {PbPb}$ collisions at a centre-of-mass energy per nucleon pair of $\sqrt{\smash [b]{s_{_{\text {NN}}}}} = 5.02\,\text {Te}\text {V} $ . The analysis is based on $\text {PbPb}$ and $\mathrm {p}\mathrm {p}$ data samples collected by CMS at the LHC in 2015, corresponding to integrated luminosities of 464 $\,\mu \mathrm {b}^{-1}$ and 28 $\,\text {pb}^\text {-1}$ , respectively. The measurements are performed in the dimuon rapidity range of $|y | < 2.4$ as a function of centrality, rapidity, and transverse momentum ( $p_{\mathrm {T}}$ ) from $p_{\mathrm {T}} =3$ ${\,\text {Ge}\text {V}/}\text {c}$ in the most forward region and up to 50 ${\,\text {Ge}\text {V}/}\text {c}$ . Both prompt and nonprompt (coming from b hadron decays) ${\mathrm {J}/\psi }$ mesons are observed to be increasingly suppressed with centrality, with a magnitude similar to the one observed at $\sqrt{\smash [b]{s_{_{\text {NN}}}}} = 2.76\,\text {Te}\text {V} $ for the two ${\mathrm {J}/\psi }$ meson components. No dependence on rapidity is observed for either prompt or nonprompt ${\mathrm {J}/\psi }$ mesons. An indication of a lower prompt ${\mathrm {J}/\psi }$ meson suppression at $p_{\mathrm {T}} > 25$ ${\,\text {Ge}\text {V}/}\text {c}$ is seen with respect to that observed at intermediate $p_{\mathrm {T}}$ . The prompt $\psi \text {(2S)}$ meson yield is found to be more suppressed than that of the prompt ${\mathrm {J}/\psi }$ mesons in the entire $p_{\mathrm {T}}$ range.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Charmonium Transport in Heavy-Ion Collisions at the LHC

We provide an update on our semi-classical transport approach for quarkonium production in high-energy heavy-ion collisions, focusing on 𝐽/𝜓 and 𝜓(2𝑆) mesons in 5.02 TeV Pb-Pb collisions at the Large Hadron Collider (LHC) at both forward and mid-rapidity. In particular, we employ the most recent charm-production cross sections reported in pp collisions, which are pivotal for the magnitude of the regeneration contribution, and their modifications due to cold-nuclear-matter (CNM) effects. Multi-differential observables are calculated in terms of nuclear modification factors as a function of centrality, transverse momentum, and rapidity, including the contributions from feeddown from bottom hadron decays. For our predictions for 𝜓(2𝑆) production, the mechanism of sequential regeneration relative to the more strongly bound 𝐽/𝜓 meson plays an important role in interpreting recent ALICE data.

Astronomy & Astrophysics↗