We propose a mechanics of a massive particle in a potential field effective
for both classical and quantum system as a modified classical analytical
mechanics (modified CM). We transform, under coordinate transformation, the
covariant tensor of order two in the Hamilton-Jacobi (H-J) eq. of CM, not with
the classical action, but with extended action of diffeomorphism group. Then,
the H-J eq., a first-order partial differential eq., is modified to a
third-order one. The Euler-Lagrange (E-L) eq. of CM, a second-order ordinary
differential eq., related to the H-J eq. through the action integral is
accordingly modified to a fourth-order one. Thus obtained mechanics
accommodates quantum phenomena due to the higher-order eqs., and always gives
trajectory unlike quantum mechanics (QM) due to the E-L eq. Discrete energy
levels of a particle in a confining potential are the same as those of QM
because quantization criterion is equivalent. Particle distribution in an
ensemble disagrees with that of QM even if initial distribution is set
identical because dynamics is different; it however agrees with observed data
to date within experimental uncertainty. The mechanics thus is a testable
alternative to QM.Comment: 51 pages, 8 figures. A reason for 1-D energy quantization which works
on real line (R1) is given; the one in previous versions works only on real
projective line (RP1). Some other improvements were incorporate