2025/11/21 by Izabela Babiarz, Babiarz, Izabela, Piotr Lebiedowicz +5
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph) #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions
paper · pdf · doi:10.48550/arxiv.2511.16862
openalex publication_date 2025/11/21 · openalex created_date 2025/11/25 · openalex updated_date 2026/07/28
We discuss the production of D D pairs in e+ e- collisions, where D refers to either D0 or D+. The continuum mechanism with the t/u-channel vector-meson D^* exchanges are considered. The results of the calculation depend on the parameter of the off-shell form-factor for the virtual D^* mesons. The D^* D γ coupling constants are found from the D^* → D γ decays. We find relatively large contribution for the D0 D0 channel and much smaller contribution in the D+ D- channel. In the second case we consider also the D± exchanges. We conclude that the bump at M_D0 D0 = 3.8 GeV observed by the Belle and BaBar Collaborations has rather continuum origin than it corresponds to the broad resonance χc0(3860). We discuss also production of the χc2(3930) resonance which is a candidate for the χc2(2P) state. This state can decay into both D D channels, however the branching fractions are not well known at present. From a comparison of our model results to the BaBar data we find B(χc2(3930) → D D) = 0.58 ± 0.13 using the two-photon width Γγγ = 0.544 keV (obtained for the Buchmüller-Tye potential) evaluated within the light-front approach (NRQCD limit). Our finding of Γγγ × B(χc2(3930) → D D) = 0.32 ± 0.07 keV is close to the Belle and BaBar results. Realistic predictions of the differential distributions in several variables and integrated cross-sections are given for the Belle II kinematics.