  A strong departure from Landau-Fermi liquid (LFL) behavior have been recently
revealed in observed anomalies in both the magnetic susceptibility $\chi$ and
the muon and $\rm ^{63}Cu$ nuclear spin-lattice relaxation rates $1/T_1$ of
${\rm {YbCu_{5-x}Au_x}}$ ($x=0.6$). We show that the above anomalies along with
magnetic-field-induced reentrance of LFL properties are indeed determined by
the scaling behavior of the quasiparticle effective mass. We obtain the scaling
behavior theoretically utilizing our approach based on fermion condensation
quantum phase transition (FCQPT) notion. Our theoretical analysis of
experimental data on the base of FCQPT approach permits not only to explain
above two experimental facts in a unified manner, but to clarify the physical
reasons for a scaling behavior of the longitudinal magnetoresistance in $\rm
YbRh_2Si_2$.
