Polarization transfer in theH2(e→,e′p→)nreaction up toQ2=1.61(GeV/c)2

The recoil proton polarization was measured in the ${}^2\mathrm{H}$ $(\overrightarrow{e},e^{\prime }\overrightarrow{p})n$ reaction in Hall A of the Thomas Jefferson National Accelerator Facility. The electron kinematics were centered on the quasielastic peak ($x_{\mathit{Bj}}\approx 1$) and included three values of the squared four-momentum transfer, $Q^2=0.43,1.00$ and 1.61 (GeV/$c){}^2$. For $Q^2=0.43$ and 1.61 (GeV/$c){}^2$, the missing momentum, $p_m$, was centered at zero, whereas for $Q^2=1.00(\mathrm{GeV}/c){}^2$ two values of $p_m$ were chosen: 0 and $174\mathrm{MeV}/c$. At low $p_m$, the $Q^2$ dependence of the longitudinal polarization, $P_z^{\prime }$, is not well described by a state-of-the-art calculation. Further, at higher $p_m$, a 3.5σ discrepancy was observed in the transverse polarization, $P_x^{\prime }$. Understanding the origin of these discrepancies is important to confidently extract the neutron electric form factor from the analogous ${}^2\mathrm{H}$ $(\overrightarrow{e},e^{\prime }\overrightarrow{n})p$ experiment.