Measurement of the beam asymmetry Σ for π^0 and η photoproduction on the proton at E sub γ=9 GeV

Abstract

$Wereportmeasurementsofthephotonbeamasymmetry\$\Sigma \$forthereactions\${\vec {\gamma }}p\to \pi ^{0}p\$and\${\vec {\gamma }}p\to \eta p\$fromtheGlueXexperimentusinga9GeVlinearly-polarized,taggedphotonbeamincidentonaliquidhydrogentargetinJeffersonLab'sHallD.Theasymmetries,measuredasafunctionoftheprotonmomentumtransfer,possessgreaterprecisionthanprevious\$\pi ^{0}\$measurements,andarethefirst\$\eta \$measurementsinthisenergyregime.Theresultsarecomparedwiththeoreticalpredictionsbasedon\$t\$-channel,quasi-particleexchangeandconstraintheaxial-vectorcomponentoftheneutralmesonproductionmechanisminthesemodels.$