Exotic hybrid mesons in hard electroproduction - art. no. 0340201

We estimate the sizeable cross section for deep exclusive electroproduction of an exotic J(PC)=1(-+) hybrid meson in the Bjorken regime. The production amplitude scales like the one for usual meson electroproduction, i.e., as 1/Q(2). This is due to the nonvanishing leading twist distribution amplitude for the hybrid meson, which may be normalized thanks to its relation to the energy-momentum tensor and to the QCD sum rules technique. The hard amplitude is considered up to next-to-leading order in alpha(S) and we explore the consequences of fixing the renormalization scale ambiguity through the Brodsky-Lepage-Mackenzie (BLM) procedure. We study the particular case where the hybrid meson decays through a pieta meson pair. We discuss the pieta generalized distribution amplitude and then calculate the production amplitude for this process. We propose a forward-backward asymmetry in the production of pi and eta mesons as a signal for the hybrid meson production. We briefly comment on hybrid electroproduction at very high energy, in the diffractive limit where a QCD Odderon exchange mechanism should dominate. The conclusion of our study is that hard electroproduction is a promising way to study exotic hybrid mesons, in particular, at JLAB, HERA (HERMES), or CERN (Compass).