This paper is dedicated to the Cauchy problem of the incompressible Oldroyd-B
model with general coupling constant ? ?(0,1). It is shown that this set
of equations admits a unique global solution in a certain hybrid Besov
spaces for small initial data in ?Hs ??Bd/2 2,1 with - d/2 < s < d2-1.
In particular, if d ? 3, and taking s=0, then ?H0 ? ?Bd/2 2,1 = B d/2 2,1.
Since Bt2,? ? Bd/2 2,1 if t > d/2, this result extends the work by Chen
and Miao [Nonlinear Anal.,68(2008), 1928-1939].