Decays of the π^{+}π^{} atom
Abstract
We construct an effective nonrelativistic quantum field theory that describes bound states of π^{+}π^{} pairs and their hadronic decays. We then derive a general expression for the lifetime of the ground state at nexttoleading order in isospin breaking. Chiral perturbation theory allows one to relate the decay rate to the two Swave ππ scattering lengths and to several lowenergy constants that occur in the chiral Lagrangian. Recent predictions for the scattering lengths give τ=(2.9+/0.1)×10^{15} s. This result may be confronted with π^{+}π^{} lifetime measurements, like the one presently carried out at CERN.
 Publication:

Physical Review D
 Pub Date:
 July 2001
 DOI:
 10.1103/PhysRevD.64.016008
 arXiv:
 arXiv:hepph/0103157
 Bibcode:
 2001PhRvD..64a6008G
 Keywords:

 11.10.St;
 03.65.Ge;
 11.10.Ef;
 12.39.Fe;
 Bound and unstable states;
 BetheSalpeter equations;
 Solutions of wave equations: bound states;
 Lagrangian and Hamiltonian approach;
 Chiral Lagrangians;
 High Energy Physics  Phenomenology
 EPrint:
 41 pages, 8 postscript figures, uses REVTEX style