Beam-helicity asymmetries for single-hadron production in semi-inclusive deep-inelastic scattering from unpolarized hydrogen and deuterium targets

A Airapetian,A Kisselev,C Riedl,A Hillenbrand,S Belostotski,V Shutov,E Cisbani,S Yaschenko,A Fantoni,Y Van Haarlem,G Nazaryan,W Deconinck,V Muccifora,P Di Nezza,A Nass,W Lorenzon,D Veretennikov,L Lapikás,F Garibaldi,V Zagrebelnyy,A Rostomyan,V Kozlov,B Seitz,W Augustyniak,M Düren,G Rosner,M Diefenthaler,D Zeiler,A Movsisyan,Z Akopov,C Van Hulse,P Kravchenko,G Elbakian,I Lehmann,W.-D Nowak,G Karyan,F Ellinghaus,H.P Blok,M Contalbrigo,L Felawka,M Statera,V Gharibyan,G Schnell,G Gapienko,D Ryckbosch,E Kinney,H Marukyan,I Vilardi,G Ciullo,M Tytgat,P Lenisa,E De Sanctis,V Bryzgalov,L Lagamba,B Zihlmann,G Gavrilov,R Kaiser,Y Holler,A Terkulov,S Joosten,A Ivanilov,T A Shibata ,Christian Vogel ,Н Акопов ,L L Pappalardo ,A R Reolon ,B Mariański ,E C Aschenauer ,Klaus Rith ,G P Capitani ,В А Коротков ,S I Manaenkov ,H E Jackson ,A Trzciński ,P Żuprański

doi:10.1016/j.physletb.2019.134886

Abstract

A measurement of beam-helicity asymmetries for single-hadron production in deep-inelastic scattering is presented. Data from the scattering of 27.6 GeV electrons and positrons off gaseous hydrogen and deuterium targets were collected by the HERMES experiment. The asymmetries are presented separately as a function of the Bjorken scaling variable, the hadron transverse momentum, and the fractional energy for charged pions and kaons as well as for protons and anti-protons. These asymmetries are also presented as a function of the three aforementioned kinematic variables simultaneously.

Highlights

The distribution of partons inside a nucleon, N, and their fragmentation into hadrons, h, have received so far most theoretical and experimental attention at leading twist, i.e., at twist 2
In this high–transverse-momentum region, it is described in terms of the collinear, i.e., integrated over transverse momentum, spin-independent parton distribution functions (PDFs) f1 and fragmentation functions (FFs) D1, and the hadron transverse momentum in the final state finds its origin in perturbative quantum chromodynamics (QCD) radiation [26]
The present article reports a measurement of the beam-helicity asymmetry by the HERMES experiment for charged pions, charged kaons, andprotons, for data collected on hydrogen and deuterium targets

Summary

Introduction

The distribution of partons inside a nucleon, N, and their fragmentation into hadrons, h, have received so far most theoretical and experimental attention at leading twist, i.e., at twist 2 For high values of hadron transverse momentum ( Ph⊥ M), the structure function becomes of twist 2 and appears at order α2S in the strong coupling constant.2 In this high–transverse-momentum region, it is described in terms of the collinear, i.e., integrated over transverse momentum, spin-independent PDF f1 and FF D1, and the hadron transverse momentum in the final state finds its origin in perturbative QCD radiation [26]. The present article reports a measurement of the beam-helicity asymmetry by the HERMES experiment for charged pions, charged kaons, and (anti-)protons, for data collected on hydrogen and deuterium targets The usage of these two targets is interesting, because it offers different sensitivities to the valence-quark flavors. The extraction is performed in three dimensions: simultaneously in xB , z, and Ph⊥ for pions, kaons, and (anti-)protons as well as in one dimension in each of these three kinematic variables

Measurement

Results

Summary and conclusions

Methods