Dergi makalesi Açık Erişim

Accessing the strong interaction between Λ baryons and charged kaons with the femtoscopy technique at the LHC

2023    CERN İşbirliği

The interaction between Λ baryons and kaons/antikaons is a crucial ingredient for the strangeness $S=0$ and $S=-2$ sector of the meson–baryon interaction at low energies. In particular, the $\Lambda \stackrel{‾}{K}$ might help in understanding the origin of states such as the $\Xi \left(1620\right)$, whose nature and properties are still under debate. Experimental data on $\Lambda \text{–}K$ and $\Lambda \text{–}\stackrel{‾}{K}$ systems are scarce, leading to large uncertainties and tension between the available theoretical predictions constrained by such data. In this Letter we present the measurements of Λ–K${}^{+}\oplus \stackrel{‾}{\Lambda }\text{–}$K$^{−}$ and Λ–K${}^{-}\oplus \stackrel{‾}{\Lambda }\text{–}$K$^{+}$ correlations obtained in the high-multiplicity triggered data sample in pp collisions at $\sqrt{s}=13$ TeV recorded by ALICE at the LHC. The correlation function for both pairs is modeled using the Lednický–Lyuboshits analytical formula and the corresponding scattering parameters are extracted. The Λ–K${}^{-}\oplus \stackrel{‾}{\Lambda }\text{–}$K$^{+}$ correlations show the presence of several structures at relative momenta ${k}^{⁎}$ above 200 MeV/c, compatible with the Ω baryon, the $\Xi \left(1690\right)$, and $\Xi \left(1820\right)$ resonances decaying into Λ–K$^{−}$ pairs. The low ${k}^{⁎}$ region in the Λ–K${}^{-}\oplus \stackrel{‾}{\Lambda }\text{–}$K$^{+}$ also exhibits the presence of the $\Xi \left(1620\right)$ state, expected to strongly couple to the measured pair. The presented data allow to access the ΛK$^{+}$ and ΛK$^{−}$ strong interaction with an unprecedented precision and deliver the first experimental observation of the $\Xi \left(1620\right)$ decaying into ΛK$^{−}$.