Journal of high energy physics 08(8), 123 (2020). doi:10.1007/JHEP08(2020)123 The decays B$^{+}$→ J/ψπ$^{+}$π$^{−}$K$^{+}$ are studied using a data set corresponding to an integrated luminosity of 9 fb$^{−1}$ collected with the LHCb detector in proton-proton collisions between 2011 and 2018. Precise measurements of the ratios of branching fractions with the intermediate ψ$_{2}$(3823), χ$_{c1}$(3872) and ψ(2S) states are reported. The values are ${\displaystyle \begin{array}{c}\frac{{\mathcal{B}}_{{\mathrm{B}}^{+}\to {\psi}_2(3823){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\psi_2(3823)\to \mathrm{J}/{\psi \pi}^{+}{\pi}^{-}}}{{\mathcal{B}}_{{\mathrm{B}}^{+}\to {\chi}_{\mathrm{c}1}(3872){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\chi_{\mathrm{c}1}(3872)\to \mathrm{J}/{\psi \pi}^{+}{\pi}^{-}}}=\left(3.56\pm 0.67\pm 0.11\right)\times {10}^{-2},\\ {}\frac{{\mathcal{B}}_{{\mathrm{B}}^{+}\to {\psi}_2(3823){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\psi_2(3823)\to \mathrm{J}/{\psi \pi}^{+}{\pi}^{-}}}{{\mathcal{B}}_{{\mathrm{B}}^{+}\to \psi \left(2\mathrm{S}\right){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\psi \left(2\mathrm{S}\right)\to \mathrm{J}/{\psi \pi}^{+}{\pi}^{-}}}=\left(1.31\pm 0.25\pm 0.04\right)\times {10}^{-3},\\ {}\frac{{\mathcal{B}}_{\mathrm{B}+\to {\chi}_{\mathrm{c}1}(3872){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\chi_{\mathrm{c}1}(3872)\to \mathrm{J}/{\psi \pi}^{+}{\pi}^{-}}}{{\mathcal{B}}_{{\mathrm{B}}^{+}\to \psi \left(2\mathrm{S}\right){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\psi \left(2\mathrm{S}\right)\to \mathrm{J}/{\psi \pi}^{+}{\pi}^{-}}}=\left(3.69\pm 0.07\pm 0.06\right)\times {10}^{-2},\end{array}} $where the first uncertainty is statistical and the second is systematic. The decay of B$^{+}$→ ψ$_{2}$(3823)K$^{+}$ with ψ$_{2}$(3823) → J/ψπ$^{+}$π$^{−}$ is observed for the first time with a significance of 5.1 standard deviations. The mass differences between the ψ$_{2}$(3823), χ$_{c1}$(3872) and ψ(2S) states are measured to be$ {\displaystyle \begin{array}{c}{m}_{\chi_{\mathrm{c}1}(3872)}-{m}_{\psi_2(3823)}=47.50\pm 0.53\pm 0.13\;\mathrm{MeV}/{c}^2,\\ {}{m}_{\psi_2(3823)}-{m}_{\psi_2\left(2\mathrm{S}\right)}=137.98\pm 0.53\pm 0.14\;\mathrm{MeV}/{c}^2,\\ {}{m}_{\chi_{\mathrm{c}1}(3872)}-{m}_{\psi_2\left(2\mathrm{S}\right)}=185.49\pm 0.06\pm 0.03\;\mathrm{MeV}/{c}^2,\end{array}} $resulting in the most precise determination of the χ$_{c1}$(3872) mass. The width of the ψ$_{2}$(3823) state is found to be below 5.2 MeV at 90% confidence level. The Breit-Wigner width of the χ$_{c1}$(3872) state is measured to be$ {\Gamma}_{\chi_{\mathrm{c}1}(3872)}^{\mathrm{BW}}={0.96}_{-0.18}^{+0.19}\pm 0.21\;\mathrm{MeV} $which is inconsistent with zero by 5.5 standard deviations. Published by SISSA, [Trieste]
Laboratoire de Physique de Clermont (LPC), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA), Laboratoire de l'Accélérateur Linéaire (LAL), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Centre de Physique des Particules de Marseille (CPPM), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Leprince-Ringuet (LLR), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE (UMR_7585)), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), LHCb, Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)
JHEP JHEP, 2020, 08, pp.123. ⟨10.1007/JHEP08(2020)123⟩ Journal of high energy physics 08(8), 123 (2020). doi:10.1007/JHEP08(2020)123 Journal of high energy physics : JHEP 2020(8), 123 (2020). doi:10.1007/JHEP08(2020)123
DOI:
10.1007/JHEP08(2020)123⟩
Popis:
Journal of high energy physics 08(8), 123 (2020). doi:10.1007/JHEP08(2020)123 The decays B$^{+}$→ J/ψπ$^{+}$π$^{−}$K$^{+}$ are studied using a data set corresponding to an integrated luminosity of 9 fb$^{−1}$ collected with the LHCb detector in proton-proton collisions between 2011 and 2018. Precise measurements of the ratios of branching fractions with the intermediate ψ$_{2}$(3823), χ$_{c1}$(3872) and ψ(2S) states are reported. The values are ${\displaystyle \begin{array}{c}\frac{{\mathcal{B}}_{{\mathrm{B}}^{+}\to {\psi}_2(3823){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\psi_2(3823)\to \mathrm{J}/{\psi \pi}^{+}{\pi}^{-}}}{{\mathcal{B}}_{{\mathrm{B}}^{+}\to {\chi}_{\mathrm{c}1}(3872){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\chi_{\mathrm{c}1}(3872)\to \mathrm{J}/{\psi \pi}^{+}{\pi}^{-}}}=\left(3.56\pm 0.67\pm 0.11\right)\times {10}^{-2},\\ {}\frac{{\mathcal{B}}_{{\mathrm{B}}^{+}\to {\psi}_2(3823){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\psi_2(3823)\to \mathrm{J}/{\psi \pi}^{+}{\pi}^{-}}}{{\mathcal{B}}_{{\mathrm{B}}^{+}\to \psi \left(2\mathrm{S}\right){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\psi \left(2\mathrm{S}\right)\to \mathrm{J}/{\psi \pi}^{+}{\pi}^{-}}}=\left(1.31\pm 0.25\pm 0.04\right)\times {10}^{-3},\\ {}\frac{{\mathcal{B}}_{\mathrm{B}+\to {\chi}_{\mathrm{c}1}(3872){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\chi_{\mathrm{c}1}(3872)\to \mathrm{J}/{\psi \pi}^{+}{\pi}^{-}}}{{\mathcal{B}}_{{\mathrm{B}}^{+}\to \psi \left(2\mathrm{S}\right){\mathrm{K}}^{+}}\times {\mathcal{B}}_{\psi \left(2\mathrm{S}\right)\to \mathrm{J}/{\psi \pi}^{+}{\pi}^{-}}}=\left(3.69\pm 0.07\pm 0.06\right)\times {10}^{-2},\end{array}} $where the first uncertainty is statistical and the second is systematic. The decay of B$^{+}$→ ψ$_{2}$(3823)K$^{+}$ with ψ$_{2}$(3823) → J/ψπ$^{+}$π$^{−}$ is observed for the first time with a significance of 5.1 standard deviations. The mass differences between the ψ$_{2}$(3823), χ$_{c1}$(3872) and ψ(2S) states are measured to be$ {\displaystyle \begin{array}{c}{m}_{\chi_{\mathrm{c}1}(3872)}-{m}_{\psi_2(3823)}=47.50\pm 0.53\pm 0.13\;\mathrm{MeV}/{c}^2,\\ {}{m}_{\psi_2(3823)}-{m}_{\psi_2\left(2\mathrm{S}\right)}=137.98\pm 0.53\pm 0.14\;\mathrm{MeV}/{c}^2,\\ {}{m}_{\chi_{\mathrm{c}1}(3872)}-{m}_{\psi_2\left(2\mathrm{S}\right)}=185.49\pm 0.06\pm 0.03\;\mathrm{MeV}/{c}^2,\end{array}} $resulting in the most precise determination of the χ$_{c1}$(3872) mass. The width of the ψ$_{2}$(3823) state is found to be below 5.2 MeV at 90% confidence level. The Breit-Wigner width of the χ$_{c1}$(3872) state is measured to be$ {\Gamma}_{\chi_{\mathrm{c}1}(3872)}^{\mathrm{BW}}={0.96}_{-0.18}^{+0.19}\pm 0.21\;\mathrm{MeV} $which is inconsistent with zero by 5.5 standard deviations. Published by SISSA, [Trieste]
