Investigation of systematic errors and estimation of πK\pi K atom lifetime

This note describes details of analysis of data sample collected by DIRAC experiment on Ni target in 2008-2010 in order to estimate lifetime of $\pi K$ atoms. Experimental results consists of six distinct data samples: both charge combinations ($\pi^+K^−$ and $K^+\pi^−$ atoms) obtained in dierent experimental conditions corresponding to each year of data-taking. Sources of systematic errors are analyzed, and estimations of systematic errors are presented. Taking into account both statistical and systematic uncertainties, the lifetime of $\pi K$ atoms is estimated by maximum likelihood method

Observation of

Experiment DIRAC at CERN PS detects 349 ± 62 pairs from π−K+ and π+K− atoms and makes observation of exotic atoms consist of pion and kaon. It allows to measure a difference of S-wave pion-kaon scattering length with isospin 1/2 and 3/2: |a01/2−a03/2|. Values of pion-kaon scattering lengths are predicted in a frame of ChPT and LQCD. Therefore investigation of π−K+ and π+K− atoms gives possibility to check these predictions for simplest hadronhadron system with s-quark

Investigation of π+π−\pi^+ \pi^- and pipiK atoms at DIRAC

Measurement of $π^+π^−$ and $πK$ atom lifetimes allows to check prediction of Chiral Perturbation Theory for pion-pion scattering lengths with isospin 0 and 2, and pion-kaon scattering lengths with isospin 1/2 and 3/2. Current status of DIRAC experiment, expected results and proposal for future investigations are presented

The investigation of K+π−,π+K−K^+\pi^−, \pi^+K^− and π+π−\pi^+\pi^− atoms

Theory, using Low Energy QCD, predicts with high precision the pion-pion and pion-kaon scattering lengths. There is accurate relation between K^+pi^- and pi^+K^- atoms lifetime and pion-kaon S-wave scattering lengths with isospin 1/2 and 3/2. Experiment DIRAC at CERN PS detects 345 +- 61 pairs from K^+pi^- and pi^+K^- atoms breakup. It allows to achieve the first observation of exotic atoms consisted of pion and kaon. Measured values of piK atom lifetime and corresponding pion-kaon scattering length difference are presented. It is shown, that experimental accuracy for pion-kaon scattering length difference could be significantly improved with an experiment at SPS energy

Observation and investigation of π\piK atoms

There is accurate relation between lifetime of atoms, consisting of pion and kaon, and a difference of S-wave pion kaon scattering length with isospin 1/2 and 3/2: $\left | a_{1/2} - a_{3/2} \right |$. This difference is predicted by low energy QCD. Experiment DIRAC at CERN PS detects $349 \pm 62$ pairs from $K^+ \pi^−$ and $\pi^+ K^−$ atoms and make observation of exotic atoms consist of pion and kaons and provides way for measurement of pion-kaon scattering length difference and check of theoretical predictions

Investigation of π+π−,K+π−\pi^+\pi^-, K^+\pi^- and π+K−\pi^+K^- atoms for pion-pion and pion-kaon scattering length measurements

Theory, using Low Energy QCD, calculated with high precision the $\pi\pi$ and $\pi K$ scattering length. Lifetime of $\pi^+\pi^−$ atoms are related with a difference of pion-pion s-wave scattering lengths with isospin 0 and 2: $|a_0 − a_2|$. Energy splitting between p-states (long-lived atoms) and s-states of $\pi^+\pi^−$ atoms allows to investigate another combination: $2a_0 + a_2$. Lifetime of $\pi K$ atoms gives information about difference of pion-kaon s-wave scattering lengths with isospin 1/2 and 3/2: $|a_{1/2} − a_{3/2}|$. Experimental measurements of pion-kaon lifetimes and observation of long-lived $\pi^+\pi^−$ atoms at experiment DIRAC are presente