01253nas a2200133   4500008004100000245007800041210006900119260001000188520080500198100001801003700002901021700002101050856004801071       2017                        en  d00aSpectral Properties of the 2+1 Fermionic Trimer with Contact Interactions0 aSpectral Properties of the 21 Fermionic Trimer with Contact Inte  bSISSA3 aWe qualify the main features of the spectrum of the Hamiltonian of
point interaction for a three-dimensional quantum system consisting of three
point-like particles, two identical fermions, plus a third particle of different
species, with two-body interaction of zero range. For arbitrary magnitude of
the interaction, and arbitrary value of the mass parameter (the ratio between
the mass of the third particle and that of each fermion) above the stability
threshold, we identify the essential spectrum, localise and prove the finiteness
of the discrete spectrum, qualify the angular symmetry of the eigenfunctions,
and prove the monotonicity of the eigenvalues with respect to the mass parameter.
We also demonstrate the existence of bound states in a physically
relevant regime of masses.1 aBecker, Simon1 aMichelangeli, Alessandro1 aOttolini, Andrea  uhttp://preprints.sissa.it/handle/1963/35303