Experimental study of muon pairs produced by 252-GeV pions on tungsten

TLDR

The study investigates muon pair production with invariant masses above 4.05 GeV/c² in high‑energy pion‑nucleon interactions. The analysis compares the measured cross sections with a higher‑twist QCD model. The experiment measures the muon‑pair production cross section, pion and nucleon structure functions, transverse‑momentum spectra, full angular distributions, and observes longitudinal photon polarization at high pion Feynman‑x.

Abstract

We present the results of a study of muon pairs with invariant masses greater than 4.05 GeV/${c}^{2}$ produced in high-energy pion-nucleon interactions. The production cross section together with the inferred pion and nucleon structure functions are reported and compared with other experiments and with QCD predictions. The transverse-momentum distributions are also presented. Finally, the full angular distribution in cos\ensuremath{\theta} and \ensuremath{\varphi} is given as a function of mass, Feynman x, and transverse momentum. Longitudinal photon polarization is seen in the lower portion of the mass range at high ${x}_{\ensuremath{\pi}}$. This result is compared with a higher-twist model.