Measurement of the beam asymmetry Σ for π0 and η photoproduction on the proton at Eγ=9 GeV

H Al Ghoul,N Gevorgyan,I I Strakovsky,R Pedroni,R Dzhygadlo,J Schwiening,A Austregesilo,A Teymurazyan,E Chudakov,M Mccaughan,J R Stevens,E Wolin,A Toro,M Williams,Z Papandreou,S Taylor,G Vasileiadis,H Egiyan,K Livingston,A Yu Semenov,R A Schumacher,R Kliemt,W Boeglin,W K Brooks,M Patsyuk,I Tolstukhin,S Dobbs,A Barnes,J Zarling,D Werthmüller,A M Foda,A Tomaradze,M M Ito,I Larin,A Henderson,R E Mitchell,F Mokaya,K Moriya,B Pratt,B G Ritchie,A Deur,T Whitlatch,J Frye,V Matveev,J Reinhold,K K Seth,V Kakoyan,C Schwarz,A Somov,N Ochoa,D I Sober,W I Levine,F Nerling,A I Ostrovidov,C Salgado,T Black,D W Bennett,N K Walford,H Hakobyan,L Pentchev,W Mcginley,E Pooser,G J Lolos,S Somov,M M Dalton,W J Briscoe,G M Huber,B Zihlmann,M Dugger,A Gasparian,D Lawrence,M R Shepherd,P Eugenio,S Furletov,D Mack,R Miskimen,L Gan,Y Qiang,A Dolgolenko,T D Beattie,N S Jarvis,E S Smith,S Kuleshov,C A Meyer,M Lara,A Subedi,F J Klein,L Guo,G Nigmatkulov,R T Jones,V Mathieu,K Goetzen,C Kourkoumeli,C Fanelli,D G Ireland,А С Герасимов ,Bradford E Cannon ,Justin I Mcintyre ,Michael Staib ,Rodrigo Romero Méndez ,Inés De Vega ,Ivan Kuznetsov ,Ting Xiao ,P Mattione ,Dmitry Romanov ,Mahmoud M Kamel ,Lee Robison ,В В Бердников ,E.g Anassontzis ,И А Семенова ,Fernando Barbosa ,Aristeidis Tsaris ,John Hardin ,O Soto ,V Credé ,M.r Pennington ,Oleksii O Chernyshov ,Zhen-Yu Zhang ,N A Sparks ,Valery E Lyubovitskij ,V Goryachev ,K Peters ,V V Tarasov ,M E Mccracken ,Jannes Nys

doi:10.1103/physrevc.95.042201

Abstract

We report measurements of the photon beam asymmetry $\Sigma$ for the reactions $\vec{\gamma}p\to p\pi^0$ and $\vec{\gamma}p\to p\eta $ from the GlueX experiment using a 9 GeV linearly-polarized, tagged photon beam incident on a liquid hydrogen target in Jefferson Lab's Hall D. The asymmetries, measured as a function of the proton momentum transfer, possess greater precision than previous $\pi^0$ measurements and are the first $\eta$ measurements in this energy regime. The results are compared with theoretical predictions based on $t$-channel, quasi-particle exchange and constrain the axial-vector component of the neutral meson production mechanism in these models.

Highlights

Measurement of the beam asymmetry Σ for π0 and η photoproduction on the proton at Eγ = 9 GeV
We report measurements of the photon beam asymmetry Σ for the reactions γp → pπ0 and γp → pη from the GLUEX experiment using a 9 GeV linearly-polarized, tagged photon beam incident on a liquid hydrogen target in Jefferson Lab’s Hall D
Understanding the meson photoproduction mechanism at high energies is a vital component of a broader program to search for gluonic excitations in the meson spectrum through photoproduction reactions, which is the primary goal of the GLUEX experiment at Jefferson Lab

Summary

Introduction

We report measurements of the photon beam asymmetry Σ for the reactions γp → pπ0 and γp → pη from the GLUEX experiment using a 9 GeV linearly-polarized, tagged photon beam incident on a liquid hydrogen target in Jefferson Lab’s Hall D. We report on the linearly polarized photon beam asymmetry Σ in high-energy π0 and η photoproduction from the GLUEX experiment.

Results

Conclusion