Measurement of the polarizations of prompt and non-prompt J/$ψ$ and $ψ$(2S) mesons produced in pp collisions at $\sqrt{s}$ = 13 TeV
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| Formato: | Preprint |
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2024
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| _version_ | 1866916425046687744 |
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| author | CMS Collaboration |
| author_facet | CMS Collaboration |
| contents | The polarizations of prompt and non-prompt J$/ψ$ and $ψ$(2S) mesons are measured in proton-proton collisions at $\sqrt{s}$ = 13 TeV, using data samples collected by the CMS experiment in 2017 and 2018, corresponding to a total integrated luminosity of 103.3 fb$^{-1}$. Based on the analysis of the dimuon decay angular distributions in the helicity frame, the polar anisotropy, $λ_θ$, is measured as a function of the transverse momentum, $p_\mathrm{T}$, of the charmonium states, in the 25-120 and 20-100 GeV ranges for the J$/ψ$ and $ψ$(2S), respectively. The non-prompt polarizations agree with predictions based on the hypothesis that, for $p_\mathrm{T}$ $\gtrsim$ 25 GeV, the non-prompt J$/ψ$ and $ψ$(2S) are predominantly produced in two-body B meson decays. The prompt results clearly exclude strong transverse polarizations, even for $p_\mathrm{T}$ exceeding 30 times the J$/ψ$ mass, where $λ_θ$ tends to an asymptotic value around 0.3. Taken together with previous measurements, by CMS and LHCb at $\sqrt{s}$ = 7 TeV, the prompt polarizations show a significant variation with $p_\mathrm{T}$, at low $p_\mathrm{T}$. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2406_14409 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Measurement of the polarizations of prompt and non-prompt J/$ψ$ and $ψ$(2S) mesons produced in pp collisions at $\sqrt{s}$ = 13 TeV CMS Collaboration High Energy Physics - Experiment The polarizations of prompt and non-prompt J$/ψ$ and $ψ$(2S) mesons are measured in proton-proton collisions at $\sqrt{s}$ = 13 TeV, using data samples collected by the CMS experiment in 2017 and 2018, corresponding to a total integrated luminosity of 103.3 fb$^{-1}$. Based on the analysis of the dimuon decay angular distributions in the helicity frame, the polar anisotropy, $λ_θ$, is measured as a function of the transverse momentum, $p_\mathrm{T}$, of the charmonium states, in the 25-120 and 20-100 GeV ranges for the J$/ψ$ and $ψ$(2S), respectively. The non-prompt polarizations agree with predictions based on the hypothesis that, for $p_\mathrm{T}$ $\gtrsim$ 25 GeV, the non-prompt J$/ψ$ and $ψ$(2S) are predominantly produced in two-body B meson decays. The prompt results clearly exclude strong transverse polarizations, even for $p_\mathrm{T}$ exceeding 30 times the J$/ψ$ mass, where $λ_θ$ tends to an asymptotic value around 0.3. Taken together with previous measurements, by CMS and LHCb at $\sqrt{s}$ = 7 TeV, the prompt polarizations show a significant variation with $p_\mathrm{T}$, at low $p_\mathrm{T}$. |
| title | Measurement of the polarizations of prompt and non-prompt J/$ψ$ and $ψ$(2S) mesons produced in pp collisions at $\sqrt{s}$ = 13 TeV |
| topic | High Energy Physics - Experiment |
| url | https://arxiv.org/abs/2406.14409 |