  A modified version of the spinless Anderson model is studied by means of the
continuous-time quantum Monte Carlo method. This study is motivated by the
peculiar heavy-fermion behavior observed in certain Samarium compounds, which
is insensitive to magnetic field. The model involves M channels for conduction
electrons, all of which interact with local f electron via the Coulomb
repulsion Ufc, while only one channel has hybridization with the local state.
The effective hybridization is reduced by the Anderson orthogonality effect,
and a quantum critical point occurs with increasing M and/or increasing Ufc.
The numerical results at finite temperature of the local charge susceptibility
are well fitted by a simple scaling theory for all M. However, the
single-particle spectrum is described by a double Lorentzian for M>1, in
contrast with the single Lorentzian with M=1. A quasi-particle perturbation
theory is presented that reproduces the quantum critical point for large M. The
quasi-particle theory gives not only the renormalized energy scale, but its
extrapolation toward higher energies being consistent with the double
Lorentzian spectrum.
