  The static three-quark (3Q) potential is studied in detail using SU(3)
lattice QCD with $12^3 \times 24$ at $\beta=5.7$ and $16^3 \times 32$ at
$\beta=5.8$, 6.0 at the quenched level. For more than 300 different patterns of
the 3Q systems, we perform the accurate measurement of the 3Q Wilson loop with
the smearing method, which reduces excited-state contaminations, and present
the lattice QCD data of the 3Q ground-state potential $V_{\rm 3Q}$. We perform
the detailed fit analysis on $V_{\rm 3Q}$ in terms of the Y-ansatz both with
the continuum Coulomb potential and with the lattice Coulomb potential, and
find that the lattice QCD data of the 3Q potential $V_{\rm 3Q}$ are well
reproduced within a few % deviation by the sum of a constant, the two-body
Coulomb term and the three-body linear confinement term $\sigma_{\rm 3Q} L_{\rm
min}$, with $L_{\rm min}$ the minimal value of the total length of color flux
tubes linking the three quarks.
  From the comparison with the Q-$\bar {\rm Q}$ potential, we find a
universality of the string tension as $\sigma_{\rm 3Q} \simeq \sigma_{\rm Q
\bar Q}$ and the one-gluon-exchange result for the Coulomb coefficients as
$A_{\rm 3Q} \simeq \frac12 A_{\rm Q \bar Q}$. We investigate also the several
fit analyses with the various ans\"atze: the Y-ansatz with the Yukawa
potential, the $\Delta$-ansatz and a more general ansatz including the Y and
the $\Delta$ ans\"atze in some limits. All these fit analyses support the
Y-ansatz on the confinement part in the 3Q potential $V_{\rm 3Q}$, although
$V_{\rm 3Q}$ seems to be approximated by the $\Delta$-ansatz with
$\sigma_\Delta \simeq 0.53 \sigma$.

High Energy Physics - Lattice