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Measurements of $\psi(2S)$ and $X(3872) \to J/\psi\pi^+\pi^-$ production in $pp$ collisions at $\sqrt{s} = 8$ TeV with the ATLAS detector

The ATLAS collaboration
JHEP 1701 (2017) 117, 2017

Abstract (data abstract)
Differential cross sections are presented for the prompt and non-prompt production of the hidden-charm states $X(3872)$ and $\psi(2S)$, in the decay mode $J/\psi \pi^+\pi^-$, measured using 11.4~fb$^{-1}$ of $pp$ collisions at $\sqrt{s} = 8$~TeV by the ATLAS detector at the LHC. The ratio of cross-sections $X(3872)/\psi(2S)$ is also given, separately for prompt and non-prompt components, as well as the non-prompt fractions of $X(3872)$ and $\psi(2S)$. Assuming independent single effective lifetimes for non-prompt $X(3872)$ and $\psi(2S)$ production gives $R_B = \frac{\mathcal{B}(B \rightarrow X(3872)\textrm{ + any}) \mathcal{B}(X(3872) \rightarrow J\psi\pi^+\pi^-)}{\mathcal{B}(B \rightarrow \psi(2S)\textrm{ + any}) \mathcal{B}(\psi(2S) \rightarrow J\psi\pi^+\pi^-)} = (3.95 \pm 0.32 \mathrm{(stat)} \pm 0.08\mathrm{(sys)}) \times 10^{-2}$, while separating short- and long-lived contributions, assuming that the short-lived component is due to $B_c$ decays, gives $R_B = (3.57 \pm 0.33\mathrm{(stat)} \pm 0.11\mathrm{(sys)}) \times 10^{-2}$, with the fraction of non-prompt $X(3872)$ produced via $B_c$ decays for $p_\mathrm{T}(X(3872)) > 10$~GeV being $(25 \pm 13\mathrm{(stat)} \pm 2\mathrm{(sys)} \pm 5\mathrm{(spin)})\%$. The distributions of the dipion invariant mass in the $X(3872)$ and $\psi(2S)$ decays are also measured and compared to theoretical predictions.

  • Table 1

    Data from Figure 3(a)

    10.17182/hepdata.76839.v1/t1

    Measured effective pseudo-proper lifetime for non-prompt $\psi(2S)$ production.

  • Table 2

    Data from Figure 3(a)

    10.17182/hepdata.76839.v1/t2

    Measured effective pseudo-proper lifetime for non-prompt $X(3872)$ production.

  • Table 3

    Data from Figure 3(b)

    10.17182/hepdata.76839.v1/t3

    Measured non-prompt $X(3872) / \psi(2S)$ production ratio using the single-lifetime fit model.

  • Table 4

    Data from Figure 4(a)

    10.17182/hepdata.76839.v1/t4

    Measured prompt $X(3872) / \psi(2S)$ production ratio using the two-lifetime fit model.

  • Table 5

    Data from Figure 4(b)

    10.17182/hepdata.76839.v1/t5

    Measured non-prompt $X(3872) / \psi(2S)$ production ratio using the two-lifetime fit model.

  • Table 6

    Data from Figure 4(b)

    10.17182/hepdata.76839.v1/t6

    Measured short-lived non-prompt $X(3872)$ / total non-prompt $\psi(2S)$ production ratio using the two-lifetime fit model.

  • Table 7

    Data from Figure 4(b)

    10.17182/hepdata.76839.v1/t7

    Measured long-lived non-prompt $X(3872)$ / total non-prompt $\psi(2S)$ production ratio using the two-lifetime fit model.

  • Table 8

    Data from Figure 5(a)

    10.17182/hepdata.76839.v1/t8

    Measured cross section times branching fractions as a function of pT for prompt $\psi$(2S) production.

  • Table 9

    Data from Figure 5(b)

    10.17182/hepdata.76839.v1/t9

    Measured cross section times branching fractions as a function of pT for non-prompt $\psi$(2S) production.

  • Table 10

    Data from Figure 6(a)

    10.17182/hepdata.76839.v1/t10

    Measured cross section times branching fractions as a function of pT for prompt X(3872) production.

  • Table 11

    Data from Figure 6(b)

    10.17182/hepdata.76839.v1/t11

    Measured cross section times branching fractions as a function of pT for non-prompt X(3872) production.

  • Table 12

    Data from Figure 7(a)

    10.17182/hepdata.76839.v1/t12

    Measured non-prompt fraction for $\psi(2S)$ production.

  • Table 13

    Data from Figure 7(b)

    10.17182/hepdata.76839.v1/t13

    Measured non-prompt fraction for X(3872) production.

  • Table 14

    Data from Figure 9(a)

    10.17182/hepdata.76839.v1/t14

    Normalised differential decay width of $\psi(2S) \rightarrow J/\psi \pi\pi$ in bins of $m_{\pi\pi}$.

  • Table 15

    Data from Figure 9(b)

    10.17182/hepdata.76839.v1/t15

    Normalised differential decay width of $X(3872) \rightarrow J/\psi \pi\pi$ in bins of $m_{\pi\pi}$.

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