iamquantized said:
What is the best book out there on relativistic quantum mechanics for someone who has a bachelor degree in physics and pursuing graduate study now?
There is an approach to relativistic quantum mechanics which (in my humble opinion) is superior to all others. It is based on Wigner's theory of unitary representations of the Poincare group. Occasionally, these ideas are mentioned in textbooks, but I haven't seen any good systematic exposition. If at some point you get frustrated with textbooks, try these original journal articles. You might like them:
E. P. Wigner, "On unitary representations of the inhomogeneous Lorentz group", Ann. Math. 40 (1939) 149.
P. A. M. Dirac, "Forms of relativistic dynamics", Rev. Mod. Phys. 21 (1949), 392
T. D. Newton and E. P. Wigner, "Localized states for elementary systems", Rev. Mod. Phys. 21 (1949), 400
B. Bakamjian and L. H. Thomas, "Relativistic particle dynamics. II", Phys. Rev. 92 (1953), 1300
L. L. Foldy, "Relativistic particle systems with interaction", Phys. Rev. 122 (1961), 275
D. G. Currie and T. F. Jordan and E. C. G. Sudarshan, "Relativistic invariance and
Hamiltonian theories of interacting particles", Rev. Mod. Phys. 35 (1963), 350
B. D. Keister and W. N. Polyzou, "Relativistic Hamiltonian Dynamics in nuclear and particle
physics", in Advances in Nuclear Physics vol. 20, edited by J. W. Negele and E. W. Vogt,
(Plenum Press, 1991)
http://www.physics.uiowa.edu/~wpolyzou/papers/rev.pdf
Eugene.