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Study of the $\Lambda$-$\Lambda$ interaction with femtoscopy correlations in pp and p-Pb collisions at the LHC

The ALICE collaboration
No Journal Information, 2019

Abstract (data abstract)
This work presents new constraints on the existence and the binding energy of a possible $\mathrm{\Lambda}$-$\mathrm{\Lambda}$ bound state, the H-dibaryon, derived from $\mathrm{\Lambda}$-$\mathrm{\Lambda}$ femtoscopic measurements by the ALICE collaboration. The results are obtained from a new measurement using the femtoscopy technique in p-p collisions at $\sqrt{s}=13$ TeV and p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV, combined with previously published results from p-p collisions at $\sqrt{s}=7$ TeV. The $\mathrm{\Lambda}$-$\mathrm{\Lambda}$ scattering parameter space, spanned by the inverse scattering length $f_0^{-1}$ and the effective range $d_0$, is constrained by comparing the measured $\mathrm{\Lambda}$-$\mathrm{\Lambda}$ correlation function with calculations obtained within the Lednick'y model. The data are compatible with hypernuclei results and lattice computations, both predicting a shallow attractive interaction, and permit to test different theoretical approaches describing the $\mathrm{\Lambda}$-$\mathrm{\Lambda}$ interaction. The region in the $(f_0^{-1},d_0)$ plane which would accommodate a $\mathrm{\Lambda}$-$\mathrm{\Lambda}$ bound state is substantially restricted compared to previous studies. The binding energy of the possible $\mathrm{\Lambda}$-$\mathrm{\Lambda}$ bound state is estimated within an effective-range expansion approach and is found to be $B_{\Lambda\Lambda} = 3.2^{+1.6}_{-2.4}\text{(stat)}^{+1.8}_{-1.0}\text{(syst)}$ MeV.

  • Table 1a

    Data from Figure 1 (left panel)

    10.17182/hepdata.90845.v1/t1

    p-p correlation function in p-p collisions at $\sqrt{s}=13$ TeV.

  • Table 1b

    Data from Figure 1 (right panel) and Figure 2 (left panel)

    10.17182/hepdata.90845.v1/t2

    $\Lambda$-$\Lambda$ correlation function in p-p collisions at $\sqrt{s}=13$ TeV.

  • Table 2b

    Data from Figure 2 (right panel)

    10.17182/hepdata.90845.v1/t3

    $\Lambda$-$\Lambda$ correlation function in p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV.

  • Table 3-1

    Data from Figure 3 (1sigma contour)

    10.17182/hepdata.90845.v1/t4

    Exclusion plot for the $\Lambda$-$\Lambda$ scattering parameters (1$\sigma$ contour).

  • Table 3-2

    Data from Figure 3 (2sigma contour)

    10.17182/hepdata.90845.v1/t5

    Exclusion plot for the $\Lambda$-$\Lambda$ scattering parameters (2$\sigma$ contour).

  • Table 3-3

    Data from Figure 3 (3sigma contour)

    10.17182/hepdata.90845.v1/t6

    Exclusion plot for the $\Lambda$-$\Lambda$ scattering parameters (3$\sigma$ contour).

  • Table 4 STAT

    Data from Figure 4 (statistical uncertainty)

    10.17182/hepdata.90845.v1/t7

    Exclusion plot for the $\Lambda$-$\Lambda$ binding energy (statistical uncertainty).

  • Table 4 TOT

    Data from Figure 4 (total uncertainty)

    10.17182/hepdata.90845.v1/t8

    Exclusion plot for the $\Lambda$-$\Lambda$ binding energy (total uncertainty).

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