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Observation of $B^+\rightarrow J/\psi 3\pi^+ 2\pi^-$ and $B^+\rightarrow \psi(2S) \pi^+\pi^+\pi^-$ decays

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Abstract

The decays $B^+\rightarrow J/\psi 3\pi^+ 2\pi^-$ and $B^+\rightarrow \psi(2S) \pi^+\pi^+\pi^-$ are observed for the first time using a data sample corresponding to an integrated luminosity of $3.0fb^{-1}$, collected by the LHCb experiment in proton-proton collisions at the centre-of-mass energies of 7 and 8 TeV. The branching fractions relative to that of $B^+ \rightarrow \psi(2S)K^+$ are measured to be \begin{eqnarray*} \frac {\mathcal{B}\left(B^+\rightarrow J/\psi 3\pi^+ 2\pi^- \right)} {\mathcal{B}\left(B^+ \rightarrow \psi(2S)K^+ \right)} & = & \left(1.88\pm0.17\pm0.09\right)\times10^{-2}, \frac {\mathcal{B}\left(B^+\rightarrow \psi(2S) \pi^+\pi^+\pi^- \right)} {\mathcal{B}\left(B^+ \rightarrow \psi(2S)K^+ \right)} & = & \left(3.04\pm0.50\pm0.26\right)\times10^{-2}, \end{eqnarray*} where the first uncertainties are statistical and the second are systematic.

Figures and captions

(a) Mass distributions of the selected $ B ^+ \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} 3\pi ^+ 2\pi ^- $ candidates. (b) Sum of mass distributions for all backgrounddash-subtracted $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi ^+ \pi ^- $ combinations. The total fit function is shown with thick solid (orange) lines and the signal contribution with thin solid (red) lines. The dashed (blue) lines represent the combinatorial background and nondash-resonance component for plots (a) and (b), respectively.

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Mass distributions (a) of the selected $ B ^+ \rightarrow \psi {(2\mathrm{S})} K ^+ $ candidates and (b) backgrounddash-subtracted $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi ^+ \pi ^- $ combination. The total fit function is shown with thick solid (orange) lines and the signal contribution with thin solid (red) lines. The dashed (blue) lines represent the combinatorial background and nondash-resonance component for plots (a) and (b), respectively.

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(a) Mass distribution of the selected $ B ^+ \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} 3\pi ^+ 2\pi ^- $ candidates with the additional requirement of every $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \pi ^+ \pi ^- $ combination to be outside of $\pm6 {\mathrm{\,MeV\!/}c^2} $ around the known $\psi {(2\mathrm{S})}$ mass. The total fit function, the $ B ^+$ signal contribution and the combinatorial background are shown with thick solid\,(orange), thin solid\,(red) and dashed\,(blue) lines, respectively. (b) Sum of mass distributions for all possible backgrounddash-subtracted $\pi ^+ \pi ^- $ combinations. The factorisationdash-based model prediction is shown by a solid\,(red) line, and the expectation from the phasedash-space model is shown by a dashed\,(blue) line. The total fit function, shown with a dotted\,(green) line, is an incoherent sum of a relativistic Breitdash-Wigner function with the mean and natural width fixed to the known $\rho ^{0}$ values and a phasedash-space function multiplied by a seconddash-order polynomial.

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Distributions of (a) $\pi ^- \pi ^- $, (b) $\pi ^+ \pi ^+ $, (c) $\pi ^+ \pi ^+ \pi ^- $, (d) $\pi ^+ \pi ^- \pi ^- $, (e) $\pi ^+ \pi ^+ \pi ^+ $, (f) $2\pi ^+ 2\pi ^- $, (g) $3\pi ^+ \pi ^- $ and (h) $3\pi ^+ 2\pi ^- $ masses in the $ B ^+ \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} 3\pi ^+ 2\pi ^- $ decay. The prediction from the factorisationdash-based model is shown by solid (red) lines, and the expectation from the phasedash-space model is shown by dashed (blue) lines.

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Distributions of (a) $\pi ^+ \pi ^- $, (b) $\pi ^+ \pi ^+ $ and (c) $\pi ^+ \pi ^+ \pi ^- $ masses in the $ B ^+ \rightarrow \psi {(2\mathrm{S})} \pi ^+ \pi ^+ \pi ^- $ decay. The predictions from the factorisationdash-based model is shown by solid (red) lines, and the expectation from the phasedash-space model is shown by dashed (blue) lines.

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Animated gif made out of all figures.

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Tables and captions

Signal yields, $N$, of $ B ^+ $ decay channels. Uncertainties are statistical only.

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The $\chi^2$ per degree of freedom for the factorisationdash-based and phasedash-space models for the multipion system in nondash-resonant $ B ^+ \rightarrow { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} 3\pi ^+ 2\pi ^- $ decays.

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The $\chi^2$ per degree of freedom for the factorisationdash-based and phasedash-space models for the multipion system recoiling against $\psi {(2\mathrm{S})} $ in $ B ^+ \rightarrow \psi {(2\mathrm{S})} \pi ^+ \pi ^+ \pi ^- $ decays.

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Relative systematic uncertainties (in %) for the ratios of branching fractions. The total uncertainty is the quadratic sum of the individual components.

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Created on 09 December 2018.Citation count from INSPIRE on 18 December 2018.