First $\pi K$ atom lifetime and $\pi K$ scattering length measurements

Abstract

The results of a search for hydrogen-like atoms consisting of ${\pi }^{\mp }{K}^{\pm }$ mesons are presented. Evidence for $\pi K$ atom production by 24 GeV/c protons from CERN PS interacting with a nickel target has been seen in terms of characteristic $\pi K$ pairs from their breakup in the same target ($178\pm 49$) and from Coulomb final state interaction ($653\pm 42$). Using these results the analysis yields a first value for the $\pi K$ atom lifetime of $\tau =(2.5_{-1.8}^{+3.0})$ fs and a first model-independent measurement of the S-wave isospin-odd $\pi K$ scattering length $\left|a_0^{-}\right|=\frac{1}{3}\left|a_{1/2}-a_{3/2}\right|=\left(0.11_{-0.04}^{+0.09}\right)M_{\pi }^{-1}$ ($a_I$ for isospin $I$).

arXiv comment14 pages, 8 figures

References in corpus (13)

• ππscattering
• A new analysis of $\pi K$ scattering from Roy and Steiner type equations
• K pi scattering for isospin 1/2 and 3/2 in lattice QCD
• $\pi K$ Scattering in Three Flavour ChPT
• Scattering lengths for two pseudoscalar meson systems
• Determination of $\pi \pi$ scattering lengths from measurement of ${\pi }^{+}{\pi }^{-}$ atom lifetime
• DIRAC: A High Resolution Spectrometer for Pionium Detection
• Decay widths and energy shifts of pi pi and pi K atoms
• Isospin violation in low-energy charged pion-kaon scattering
• A Monte Carlo Calculation of the Pionium Break-up Probability with Different Sets of Pionium Target Cross Sections
• Evidence for $\pi K$-atoms with DIRAC
• Ratio of productions of pi+pi-atoms to free pi+pi- pairs with account of the strong interaction in final states
• Direct calculation of the probability of pionium ionization in the target

Cited by in corpus (10)

• The pion-kaon scattering amplitude constrained with forward dispersion relations up to 1.6 GeV
• Dispersive $\pi K\to \pi K$ and $\pi \pi \to K\bar{K}$ amplitudes from scattering data, threshold parameters and the lightest strange resonance $\kappa$ or $K_0^{\ast }(700)$
• $I=1/2$ $S$-wave and $P$-wave $K\pi$ scattering and the $\kappa$ and $K^{\ast }$ resonances from lattice QCD
• Observation of ${\pi }^{-}{K}^{+}$ and ${\pi }^{+}{K}^{-}$ atoms
• Measurement of the $\pi K$ atom lifetime and the $\pi K$ scattering length
• Theoretical aspects of Chiral Dynamics
• Chiral Nonet Mixing in $\pi K$ Scattering
• First measurement of a long-lived ${\pi }^{+}{\pi }^{-}$ atom lifetime
• New Preshower detector for DIRAC Experiment
• Investigation of $K^{+}{K}^{-}$ pairs in the effective mass region near $2m_K$