  This paper is a corrected version of Phys. Rev. B 95, 165404 (2017), which we
have retracted because it contained a trivial but fatal sign error that lead to
incorrect conclusions. --- We extend a recently-eveloped Fermi-liquid (FL)
theory for the asymmetric single-impurity Anderson model [C. Mora $et al.$,
Phys. Rev. B, 92, 075120 (2015)] to the case of an arbitrary local magnetic
field. To describe the system's low-lying quasiparticle excitations for
arbitrary values of the bare Hamiltonian's model parameters, we construct an
effective low-energy FL Hamiltonian whose FL parameters are expressed in terms
of the local level's spin-dependent ground-state occupations and their
derivatives with respect to level energy and local magnetic field. These
quantities are calculable with excellent accuracy from the Bethe Ansatz
solution of the Anderson model. Applying this effective model to a quantum dot
in a nonequilibrium setting, we obtain exact results for the curvature of the
spectral function, $c_A$, describing its leading $\sim\varepsilon^2$ term, and
the transport coefficients $c_V$ and $c_T$, describing the leading $\sim V^2$
and $\sim T^2$ terms in the nonlinear differential conductance. A sign change
in $c_A$ or $c_V$ is indicative of a change from a local maximum to a local
minimum in the spectral function or nonlinear conductance, respectively, as is
expected to occur when an increasing magnetic field causes the Kondo resonance
to split into two subpeaks. We find that the fields $B_A$, $B_T$ and $B_V$ at
which $c_A$, $c_T$ and $c_V$ change sign, respectively, are all of order $T_K$,
as expected, with $B_A = B_T = B_V = 0.75073\,T_K$ in the Kondo limit.
