Competition of $χ_{c}(2P)$ quarkonia and continuum in $e^+ e^- \to e^+ e^- D \bar{D}$
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| Formato: | Preprint |
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2025
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| _version_ | 1866911474309398528 |
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| author | Babiarz, Izabela Lebiedowicz, Piotr Schäfer, Wolfgang Szczurek, Antoni |
| author_facet | Babiarz, Izabela Lebiedowicz, Piotr Schäfer, Wolfgang Szczurek, Antoni |
| contents | We discuss the production of $D \bar{D}$ pairs in $e^+ e^-$ collisions, where $D$ refers to either $D^0$ 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 $D^* \to D γ$ decays. We find relatively large contribution for the $D^0 {\bar D}^0$ channel and much smaller contribution in the $D^+ D^-$ channel. In the second case we consider also the $D^{\pm}$ exchanges. We conclude that the bump at $M_{D^0 {\bar D}^0} = 3.8$ GeV observed by the Belle and BaBar Collaborations has rather continuum origin than it corresponds to the broad resonance $χ_{c0}(3860)$. We discuss also production of the $χ_{c2}(3930)$ resonance which is a candidate for the $χ_{c2}(2P)$ state. This state can decay into both $D \bar{D}$ channels, however the branching fractions are not well known at present. From a comparison of our model results to the BaBar data we find $B(χ_{c2}(3930) \to D \bar{D}) = 0.58 \pm 0.13$ using the two-photon width $Γ_{γγ} = 0.544$ keV (obtained for the Buchmüller-Tye potential) evaluated within the light-front approach (NRQCD limit). Our finding of $Γ_{γγ} \times B(χ_{c2}(3930) \to D \bar{D}) = 0.32 \pm 0.07$ 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. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2511_16862 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Competition of $χ_{c}(2P)$ quarkonia and continuum in $e^+ e^- \to e^+ e^- D \bar{D}$ Babiarz, Izabela Lebiedowicz, Piotr Schäfer, Wolfgang Szczurek, Antoni High Energy Physics - Phenomenology High Energy Physics - Experiment We discuss the production of $D \bar{D}$ pairs in $e^+ e^-$ collisions, where $D$ refers to either $D^0$ 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 $D^* \to D γ$ decays. We find relatively large contribution for the $D^0 {\bar D}^0$ channel and much smaller contribution in the $D^+ D^-$ channel. In the second case we consider also the $D^{\pm}$ exchanges. We conclude that the bump at $M_{D^0 {\bar D}^0} = 3.8$ GeV observed by the Belle and BaBar Collaborations has rather continuum origin than it corresponds to the broad resonance $χ_{c0}(3860)$. We discuss also production of the $χ_{c2}(3930)$ resonance which is a candidate for the $χ_{c2}(2P)$ state. This state can decay into both $D \bar{D}$ channels, however the branching fractions are not well known at present. From a comparison of our model results to the BaBar data we find $B(χ_{c2}(3930) \to D \bar{D}) = 0.58 \pm 0.13$ using the two-photon width $Γ_{γγ} = 0.544$ keV (obtained for the Buchmüller-Tye potential) evaluated within the light-front approach (NRQCD limit). Our finding of $Γ_{γγ} \times B(χ_{c2}(3930) \to D \bar{D}) = 0.32 \pm 0.07$ 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. |
| title | Competition of $χ_{c}(2P)$ quarkonia and continuum in $e^+ e^- \to e^+ e^- D \bar{D}$ |
| topic | High Energy Physics - Phenomenology High Energy Physics - Experiment |
| url | https://arxiv.org/abs/2511.16862 |