Quasielastic rho0 electroproduction on the proton at intermediate energy: Role of scalar and pseudoscalar meson exchange

TL;DR

This paper analyzes rho0 electroproduction at intermediate energies, emphasizing the roles of scalar and pseudoscalar meson exchanges, and compares theoretical predictions with recent CLAS experimental data.

Contribution

It introduces an effective Lagrangian approach to distinguish the contributions of various meson exchanges in rho0 electroproduction, highlighting the importance of pi(0) exchange and scalar mesons.

Findings

pi(0) exchange dominates transverse cross section

Scalar meson exchanges are key for longitudinal cross section

Model with quarkonium scalar mesons fits CLAS data well

Abstract

We present a detailed analysis of rho(0) electroproduction at intermediate energy for quasi-elastic knockout kinematics. The approach is based on an effective Lagrangian which generates exchanges of scalar, pseudoscalar, axial-vector and tensor mesons. The specific role of mesons with different values for J(PC) is analyzed. We show that the pi(0) exchange amplitude and its interference terms with eta(eta') and f1 exchanges dominate in the transverse part of the cross section sigmaT. The main role plays the pi(0) to rho(0) M1 spin transition when coupling the virtual photons to the nucleon. In contrast, the longitudinal cross section sigmaL is generated by a series of scalar meson exchanges. To extract the dominant term more detailed information on the inner structure of scalar mesons is required. It turns out that recent data of the CLAS Collaboration on sigmaL and sigmaT can be described with reasonable accuracy if one proposes the quarkonium structure for the heavy scalar mesons (M > 1.3 GeV). On this basis the differential cross sections dsigmaL/dt and dsigmaT/dt are calculated and compared with the latest CLAS data.