  Physicists are engaged in vigorous debate on the nature of the quantum
critical points (QCP) governing the low-temperature properties of heavy-fermion
(HF) metals. Recent experimental observations of the much-studied compound
YbRh2Si2 in the regime of vanishing temperature incisively probe the nature of
its magnetic-field-tuned QCP. The jumps revealed both in the residual
resistivity rho_0 and the Hall resistivity R_H, along with violation of the
Wiedemann-Franz law, provide vital clues to the origin of such non-Fermi-liquid
behavior. The empirical facts point unambiguously to association of the
observed QCP with a fermion-condensation phase transition. Based on this
insight, the resistivities rho_0 and R_H are predicted to show jumps at the
crossing of the QCP produced by application of a magnetic field, with attendant
violation of the Wiedemann-Franz law. It is further demonstrated that
experimentally identifiable multiple energy scales are related to the scaling
behavior of the effective mass of the quasiparticles responsible for the
low-temperature properties of such HF metals.
