Journal Article

Evidence for an \\\\eta _c(1S) \\pi ^-\\ resonance in \\B^0 \\rightarrow \\eta _c(1S) K^+\\pi ^-\\ decays

Girard, O G, Jalocha, J, Chekalina, V, Murray, D, Tonelli, D, Marangotto, D, Hennessy, K, Mathad, A, Gys, T, Vecchi, S, Dzyuba, A, Pappalardo, L L, Sarpis, G, Gazzoni, G, Pisani, F, Jurik, N, Kuonen, A K, Williams, M R J, Jans, E, Lionetto, F, Viemann, H, Kucharczyk, M, E van Herwijnen, Petridis, K, Dujany, G, Tisserand, V, Borsato, M, Mulder, M, Fini, R A, Likhomanenko, T, Wislicki, W, Punzi, G, Beddow, J, Benson, S, Evans, T, Qin, J, Perret, P, Mödden, A, Kandybei, S, Santovetti, E, Couturier, B, Needham, M, Baryshnikov, F, Wishahi, J, Chamont, D, Matev, R, Alepuz, C Remon, Bezshyiko, Ia, Giubega, L, Patrignani, C, Campana, P, Prouve, C, Wotton, S A, Harnew, S T, Klimaszewski, K, Carson, L, Batozskaya, V, Govorkova, E, Straumann, U, R Tourinho Jadallah Aoude, Keizer, F, Gan, Y, Parkes, C, Wilson, F F, Alves, A A, J Garra Tico, B Garcia Plana, Yin, H, Bhasin, S, L Ferreira Lopes, Wark, H M, Swientek, K, Skiba, I, Gersabeck, E, Lisovskyi, V, Gersabeck, M, Tekampe, T, Volkov, V, M Féo Pereira Rivello Carvalho, Richards, S, Rotondo, M, J García Pardiñas, M van Beuzekom, Johnson, D, Massafferri, A, Comerma-Montells, A, Luppi, E, Neri, N, Stefkova, S, Kazeev, N, Tra

2018

Overview

A Dalitz plot analysis of \\[{{B} ^0} \\!\\rightarrow \\eta _c(1S) {{K} ^+} {{\\pi } ^-} \\] decays is performed using data samples of pp collisions collected with the \\[\\text{ LHCb } \\] detector at centre-of-mass energies of \\[{\\sqrt{s}} =7,~8\\] and \\[13{\\,\\mathrm {Te}\\mathrm {V}} \\], corresponding to a total integrated luminosity of \\[4.7 \\,\\text{ fb }^{-1} \\]. A satisfactory description of the data is obtained when including a contribution representing an exotic \\[\\eta _c(1S) \\pi ^-\\] resonant state. The significance of this exotic resonance is more than three standard deviations, while its mass and width are \\[4096 \\pm 20~^{+18}_{-22} \\,\\mathrm {Me}\\mathrm {V} \\] and \\[152 \\pm 58~^{+60}_{-35} \\,\\mathrm {Me}\\mathrm {V} \\], respectively. The spin-parity assignments \\[J^P=0^+\\] and \\[J^{P}=1^-\\] are both consistent with the data. In addition, the first measurement of the \\[{{B} ^0} \\!\\rightarrow \\eta _c(1S) {{K} ^+} {{\\pi } ^-} \\] branching fraction is performed and gives \\[\\begin{aligned} \\displaystyle \\mathcal {B}({{B} ^0} \\!\\rightarrow \\eta _c(1S) {{K} ^+} {{\\pi } ^-} ) = (5.73 \\pm 0.24 \\pm 0.13 \\pm 0.66) \\times 10^{-4}, \\end{aligned}\\]where the first uncertainty is statistical, the second systematic, and the third is due to limited knowledge of external branching fractions.

• Publisher: Springer Nature B.V
• Subject: Luminosity / Statistical analysis / Statistical methods