Longitudinal Double Spin Asymmetry for inclusive back-to-back dimuons in polarized $p$+$p$ collisions at $\sqrt{s} = 200$ GeV

Longitudinal double spin asymmetries, $A_{LL}$, measured for hard inclusive processes (open charm, open beauty) in polarized proton-proton collisions at high energies are sensitive to the gluon polarization, $\Delta g/g$. By measuring large invariant mass muon pairs, $\Delta g/g$ is probed in the interesting region of momentum fraction $0.02\alt x \alt 0.1$, where $\Delta g/g$ is expected to be significant. The PHENIX forward spectrometers have been used to measure back-to-back muon pairs. The status of the analysis of $A_{LL}$ in polarized $p$+$p$ collisions at $\sqrt{s}=200$ GeV at RHIC will be presented.