Precision Measurement of Electromagnetic Properties of Light Pseudoscalar Mesons via the Primakoff Effect

University Of North Carolina At Wilmington, Wilmington NC

Investigators

Abstract

This project is designed to integrate important contributions to the ongoing research at Jefferson lab with an educational experience for promising undergraduate students. A team of undergraduate students and one full time faculty member will carry out this work both at Jefferson Lab and in the University of North Carolina at Wilmington (UNCW) detector development laboratory. The primary goal of this project is to optimize the undergraduate experience while making important contribution to our understanding of low energy QCD by carrying out the high precision measurements of two-photon decay widths and the transition form factors of three neutral light pseudoscalar mesons pion-zero, eta and eta' (eta-prime) via the Primakoff effect. Two basic phenomena in QCD, namely the spontaneous break of chiral symmetry and the chiral anomalies, are manifested in their most unambiguous form in the sector of light pseudoscalar mesons. The anomalies particularly drive the two-photon decays of the pion-zero, eta and eta' and also provide a large fraction of the eta' mass. The UNCW group will work on current development of a high precision measurement of neutral pion lifetime experiment, while the advent of a 12 GeV electron beam at Jefferson Laboratory will make it possible to extend this program to eta and eta'. These measurements would have a significant impact on the current knowledge of the ratios of quark masses, the mixing angle of eta and eta', and provide model independent extractions of the size of the electromagnetic interaction radii of mesons. In addition, more precise knowledge of the transition form factors of the pseudoscalar mesons will allow a better determination of the light-by-light scattering contributions to the anomalous magnetic moment of the muon, which is one of the most sensitive quantities to new physics beyond the Standard Model. The UNCW group will play a leading role in developing a multi-channel scintillating beam profile detector, optimizing the experimental setup for future eta and eta' measurements by Monte Carlo simulation, while continuing to make significant contributions to develop a multi-channel crystal calorimeter and pair-spectrometer projects for the neutral pion lifetime measurement experiment. This research will engage undergraduate science majors as key contributors. The involvement of undergraduates has become one of the trademarks of the UNCW research group and matches the university's commitment to provide a high quality undergraduate learning experience