@article{154,
  abstract     = {We give a lower bound on the ground state energy of a system of two fermions of one species interacting with two fermions of another species via point interactions. We show that there is a critical mass ratio m2 ≈ 0.58 such that the system is stable, i.e., the energy is bounded from below, for m∈[m2,m2−1]. So far it was not known whether this 2 + 2 system exhibits a stable region at all or whether the formation of four-body bound states causes an unbounded spectrum for all mass ratios, similar to the Thomas effect. Our result gives further evidence for the stability of the more general N + M system.},
  author       = {Moser, Thomas and Seiringer, Robert},
  issn         = {15729656},
  journal      = {Mathematical Physics Analysis and Geometry},
  number       = {3},
  publisher    = {Springer},
  title        = {{Stability of the 2+2 fermionic system with point interactions}},
  doi          = {10.1007/s11040-018-9275-3},
  volume       = {21},
  year         = {2018},
}