Stability and hyperfine structure of the four- and five-body muon-atomic clusters a

Based on the results of accurate variational calculations we demonstrate stability of the five-body negatively charged ions a+b+μ−e−e−. Each of these five-body ions contains two electrons e−, one negatively charged muon μ− and two nuclei of the hydrogen isotopes a,b = (p,d,t). The bound state properties of these five-body ions, including their hyperfine structure, are briefly discussed. We also investigate the hyperfine structure of the ground states of the four-body muonic quasi-atoms a+b+μ−e−. In particular, we determine the hyperfine structure splittings for the ground state of the four-body muonic quasi-atoms: p+d+μ−e− and p+t+μ−e−