Abstract
The study of the strength and behavior of the antikaon-nucleon (K[over ¯]N) interaction constitutes one of the key focuses of the strangeness sector in low-energy quantum chromodynamics (QCD). In this Letter a unique high-precision measurement of the strong interaction between kaons and protons, close and above the kinematic threshold, is presented. The femtoscopic measurements of the correlation function at low pair-frame relative momentum of (K^{+}p⊕K^{-}p[over ¯]) and (K^{-}p⊕K^{+}p[over ¯]) pairs measured in pp collisions at sqrt[s]=5, 7, and 13TeV are reported. A structure observed around a relative momentum of 58 MeV/c in the measured correlation function of (K^{-}p⊕K^{+}p[over ¯]) with a significance of 4.4σ constitutes the first experimental evidence for the opening of the (K[over ¯]^{0}n⊕K^{0}n[over ¯]) isospin breaking channel due to the mass difference between charged and neutral kaons. The measured correlation functions have been compared to Jülich and Kyoto models in addition to the Coulomb potential. The high-precision data at low relative momenta presented in this work prove femtoscopy to be a powerful complementary tool to scattering experiments and provide new constraints above the K[over ¯]N threshold for low-energy QCD chiral models.
Highlights
The kaon (K) nucleon (N) and antikaon ðK ÞN interactions constitute the building blocks of low energy quantum chromodynamics (QCD) with u, d, and s quarks, since the effective theories aiming to describe hadron interactions in the nonperturbative energy regime are anchored to these interactions
The interaction of K and Kwith protons and neutrons has been studied by performing scattering experiments at low energies
The analysis presented here is based on minimum bias triggered pp collisions collected by the ALICE experiment
Summary
The kaon (K) nucleon (N) and antikaon ðK ÞN interactions constitute the building blocks of low energy QCD with u, d, and s quarks, since the effective theories aiming to describe hadron interactions in the nonperturbative energy regime are anchored to these interactions. The Kn-KN coupling is very important to understand the interaction and structure of the Λð1405Þ and its effect should be visible in the total K−p cross section measured in scattering experiments as a clear cusplike structure for a kaon incident momentum of plab 1⁄4 89 MeV=c [26].
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