Investigating the role of strangeness in baryon$-$antibaryon annihilation at the LHC

The collaboration
Phys.Lett.B 829 (2022) 137060, 2022.

Abstract (data abstract)
Annihilation dynamics plays a fundamental role in the baryon--antibaryon ($B-\overline{B}$) interaction at low-energy and its strength and range are crucial in the assessment of possible baryon bound states. Experimental data on annihilation cross sections are available for the $p-\overline{p}$ system but not in the low relative momentum region. Data regarding the $B-\overline{B}$ interaction with strange degrees of freedom are extremely scarce or absent, hence the modeling of the annihilation contributions is mainly based on nucleon--antinucleon ($N-\overline{N}$) results, when available. In this letter we present a measurement of the $p-\overline{p}$, $p-\overline{\Lambda}\oplus \Lambda-\overline{p}$ and $\Lambda-\overline{\Lambda}$ interaction using correlation functions in the relative momentum space in high-multiplicity triggered pp collisions at \onethree recorded by ALICE at the LHC. In the $p-\overline{p}$ system the couplings to the mesonic channels in different partial waves are extracted by adopting a coupled-channel approach with recent $\chi$EFT potentials. The inclusion of these inelastic channels provides good agreement with the data, showing a significant presence of the annihilation term down to zero momentum. Predictions obtained using the Lednick$\'y$--Lyuboshits formula and scattering parameters obtained from heavy-ion collisions, hence mainly sensitive to elastic processes, are compared with the experimental $p-\overline{\Lambda}\oplus \Lambda-\overline{p}$ and $\Lambda-\overline{\Lambda}$ correlations. The model describes the $\Lambda-\overline{\Lambda}$ data and underestimates the $p-\overline{\Lambda}\oplus \Lambda-\overline{p}$ data in the region of momenta below 200 MeV/$c$. The observed deviation indicates a different contribution of annihilation channels to the two systems containing strange hadrons.

• #### Table 1

Data from Figure 1 and 2

10.17182/hepdata.128683.v1/t1

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

• #### Table 2

Background correlation from Figure 2

10.17182/hepdata.128683.v1/t2

$C_{background}$ correlation for $p-\overline{p}$ pairs assuming chiral potentials with annihilation channels in high-multiplicity pp collisions at $\sqrt{s}=13$ TeV.

• #### Table 3 (left)

Data from Figure 3 (left panel)

10.17182/hepdata.128683.v1/t3

• #### Table 4 Background (top left)

Background correlation from Figure 4 (top left panel)

10.17182/hepdata.128683.v1/t8

$C_{background}$ correlation for $p-\overline{\Lambda}\oplus \Lambda-\overline{p}$ pairs with a simultaneous fit of Im$\mathrm{f_0}$ and $\mathrm{d_0}$ in high-multiplicity pp collisions at $\sqrt{s}=13$...

• #### Table 4 (top right)

Data from Figure A.1 in appendix (top right panel)

10.17182/hepdata.128683.v1/t9

• #### Table 4 Background (middle left)

Background correlation from Figure 4 (middle left panel)

10.17182/hepdata.128683.v1/t12

$C_{background}$ correlation for $p-\overline{\Lambda}\oplus \Lambda-\overline{p}$ pairs with a simultaneous fit of Im$\mathrm{f_0}$ and $\mathrm{d_0}$ in high-multiplicity pp collisions at $\sqrt{s}=13$...

• #### Table 4 (middle right)

Data from Figure A.1 in appendix (middle right panel)

10.17182/hepdata.128683.v1/t13

• #### Table 4 Background (bottom center)

Background correlation from Figure 4 (bottom center panel)

10.17182/hepdata.128683.v1/t16

$C_{background}$ correlation for $p-\overline{\Lambda}\oplus \Lambda-\overline{p}$ pairs with a simultaneous fit of Im$\mathrm{f_0}$ and $\mathrm{d_0}$ in high-multiplicity pp collisions at $\sqrt{s}=13$...

• #### Table 5 (left)

Data from Figure A.2 (left panel)

10.17182/hepdata.128683.v1/t17

$\Lambda-\overline{\Lambda}$ correlation function in high-multiplicity pp collisions at $\sqrt{s}=13$ TeV for the trasverse mass bin $1.08 < m_T < 1.32$...

• #### Table 5 Background (left)

Background correlation from Figure A.2 (right panel)

10.17182/hepdata.128683.v1/t18

$C_{background}$ correlation for $\Lambda-\overline{\Lambda}$ pairs with a simultaneous fit of Im$\mathrm{f_0}$ and $\mathrm{d_0}$ in high-multiplicity pp collisions at $\sqrt{s}=13$ TeV...

• #### Table 5 (right)

Data from Figure A.2 (right panel)

10.17182/hepdata.128683.v1/t19

$\Lambda-\overline{\Lambda}$ correlation function in high-multiplicity pp collisions at $\sqrt{s}=13$ TeV for the trasverse mass bin $1.32 < m_T < 1.65$...

• #### Table 5 Background (right)

Background correlation from Figure A.2 (right panel)

10.17182/hepdata.128683.v1/t20

$C_{background}$ correlation for $\Lambda-\overline{\Lambda}$ pairs with a simultaneous fit of Im$\mathrm{f_0}$ and $\mathrm{d_0}$ in high-multiplicity pp collisions at $\sqrt{s}=13$ TeV...