Journal Article

Near-threshold$$ \\mathrm{D}\\overline{\\mathrm{D}} $$spectroscopy and observation of a new charmonium state

Vorobyev, V., Chefdeville, M., Di Canto, A., Alexander, M., Jones, C. R., Durante, P., Gao, Y., Brossa Gonzalo, A., Yang, Z., Cardinale, R., Meinert, N., Mead, J. V., Barlow, R. J., Schmelling, M., Vázquez Sierra, C., Tourinho Jadallah Aoude, R., Cai, H., Bedeschi, F., Swientek, K., Stefko, P., Millard, E., Pugatch, V., Ketel, T., Ekelhof, R., Bobulska, D., Ferro-Luzzi, M., Lefèvre, R., Golubkov, D., Dalseno, J., Jawahery, A., Lai, A., Schneider, O., Rama, M., Bozzi, C., Carniti, P., Tran, M. T., Fontana, M., Straticiuc, M., Cenci, R., Ene, A., Smith, E., Gibson, V., Mulder, M., Ramos Pernas, M., Jiang, F., Bezshyiko, Ia, Beliy, N., Tuning, N., Kvaratskheliya, T., Morris, A. B., Williams, T., Carboni, G., Didenko, S., McNulty, R., Baldini, W., Ponce, S., Jalocha, J., Karacson, M., Nguyen-Mau, C., Pomery, G. J., Decamp, D., Hancock, T. H., Skidmore, N., Romanovskiy, V., Kolpin, M., Malecki, B., Cadeddu, S., Pappagallo, M., Kecke, M., Nanut, T., Marino, P., Materok, M., Merli, A., Dey, B., Yu, J., Byczynski, W., Zarebski, K. A., Hatch, M., Mogini, A., Coelho, J. A. B., Yin, H., Quagliani, R., Pikies, M., Nguyen, T. D., Parkes, C., Ferrari, F., Malinin, A., O

2019

Overview

Using proton-proton collision data, corresponding to an integrated luminosity of 9 fb −1 , collected with the LHCb detector between 2011 and 2018, a new narrow charmonium state, the X(3842) resonance, is observed in the decay modes$$ \\mathrm{X}(3842)\\to {D}^0{\\overline{D}}^0 $$X 3842 → D 0 D ¯ 0 and X(3842) → D + D − . The mass and the natural width of this state are measured to be$$ \\begin{array}{l}{m}_{X(3842)}=3842.71\\pm 0.16\\pm 0.12\\ MeV/{c}^2,\\hfill \\\ {}{\\varGamma}_{X(3842)}=2.79\\pm 0.51\\pm 0.35\\ MeV,\\hfill \\end{array} $$m X 3842 = 3842.71 ± 0.16 ± 0.12 M e V / c 2 , Γ X 3842 = 2.79 ± 0.51 ± 0.35 M e V , where the first uncertainty is statistical and the second is systematic. The observed mass and narrow natural width suggest the interpretation of the new state as the unobserved (spin-3 ψ 3 1 3 D 3 ) charmonium state. In addition, prompt hadroproduction of the ψ (3770) and χ 2 (3930) states is observed for the first time, and the parameters of these states are measured to be$$ \\begin{array}{l}{m}_{\\psi (3770)}=3778.1\\pm 0.7\\pm 0.6\\ MeV/{c}^2,\\hfill \\\ {}{m}_{\\chi_2(3930)}=3921.9\\pm 0.6\\pm 0.2\\ MeV/{c}^2,\\hfill \\\ {}{\\varGamma}_{\\chi_2(3930)}=36.6 \\pm 1.9 \\pm 0.9\\ MeV,\\hfill \\end{array} $$m ψ 3770 = 3778.1 ± 0.7 ± 0.6 M e V / c 2 , m χ 2 3930 = 3921.9 ± 0.6 ± 0.2 M e V / c 2 , Γ χ 2 3930 = 36.6 ± 1.9 ± 0.9 M e V , where the first uncertainty is statistical and the second is systematic.