  We study the local well-posedness of low regularity solutions for the Cauchy
problem of 3D relativistic Euler equations. By introducing a new decomposition
for the relativistic velocity, deriving a new transport equation for modified
vorticity, and establishing Strichartz estimates of linear wave equations
endowed with the acoustic metric, we first prove a complete local
well-posedness result for the Cauchy problem of 3D relativistic Euler equations
if the initial velocity $\bu_0=(u^0_0,\mathring{\bu}_0)^{\mathrm{T}}$,
logarithmic enthalpy $h_0$, and modified vorticity $\bw_0$ satisfy
$(h_0,\mathring{\bu}_0,\bw_0)\in H^s \times H^s \times H^{s_0} (2<s_0<s)$,
where $\mathring{\bu}_0$ is a three-vector and
$u^0_0=\sqrt{1+|\mathring{\bu}_0|^2}$. Secondly, combining the above Strichartz
estimates, semi-classical analysis, and induction method, we prove the
corresponding problem is well-posed if $(h_0,\mathring{\bu}_0,\bw_0) \in H^s
\times H^s \times H^2 (s>2)$. Our approach relies on Andersson-Zhang's work
\cite{AZ} on corresponding non-relativistic problems. All our results are valid
for a general equation of state $p(\varrho)=\varrho^\vartheta, \vartheta>1$.
