{"title":"Beam spin asymmetry benchmark in the spinless meson electroproduction off the scalar target","authors":"C. Ji, H. Choi, A. Lundeen, B. Bakker","doi":"10.22323/1.374.0049","DOIUrl":"https://doi.org/10.22323/1.374.0049","url":null,"abstract":"We discuss the electroproduction of a spinless meson, i.e. pseudoscalar ($0^{-+}$) or scalar ($0^{++}$) meson, off the scalar target. The most general formulation of the differential cross section for the $0^{-+}$ or $0^{++}$ meson process involves only one or two hadronic form factors, respectively, on a scalar target. The Rosenbluth-type separation of the differential cross section provides the explicit relation between the hadronic form factors and the different parts of the differential cross section in a completely model-independent manner. The absence of the beam spin asymmetry for the pseudoscalar meson production provides a benchmark for the experimental data analysis. The measurement of the beam spin asymmetry for the scalar meson production may also provide a unique opportunity not only to explore the imaginary part of the hadronic amplitude in the general formulation but also to examine the significance of the chiral-odd generalized parton distribution (GPD) contribution in the leading-twist GPD formulation.","PeriodicalId":299412,"journal":{"name":"Proceedings of Light Cone 2019 - QCD on the light cone: from hadrons to heavy ions — PoS(LC2019)","volume":"33 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123758358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Frame dependence of transition form factors in light-front dynamics","authors":"Meijian Li, Yang Li, P. Maris, J. Vary","doi":"10.1103/PhysRevD.100.036006","DOIUrl":"https://doi.org/10.1103/PhysRevD.100.036006","url":null,"abstract":"We study the radiative transitions between vector and pseudoscalar quarkonia in the light-front Hamiltonian approach, and investigate the effects of using different current component and different reference frames. In practical calculations with truncated Fock spaces, transition form factors may acquire current component dependence and frame dependence, and such dependences could serve as a measure for the Lorentz symmetry violation. We suggest using the transverse current with $m_j=0$ state of the vector meson, since this procedure employs the dominant spin components of the light-front wavefunctions and is more robust in practical calculations. We calculate the transition form factor between vector and pseudoscalar quarkonia and investigate the frame dependence with light-front wavefunctions calculated from the valence Fock sector. We suggest using frames with minimal longitudinal momentum transfer for calculations in the valence Fock sector, namely the Drell-Yan frame for the space-like region and a specific longitudinal frame for the timelike region; at $q^2=0$ these two frames give the same result.","PeriodicalId":299412,"journal":{"name":"Proceedings of Light Cone 2019 - QCD on the light cone: from hadrons to heavy ions — PoS(LC2019)","volume":"PP 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126413557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}