Nuclear dependence of dimuon production at 800 GeV

TLDR

The study examines dimuon production in the context of European Muon Collaboration (EMC) effect models. The experiment recorded over 450,000 dimuon events from 800‑GeV protons on deuterium, carbon, calcium, iron, and tungsten targets, measuring the per‑nucleon yield ratio R to probe nuclear antiquark sea modifications. A precise measurement of the atomic‑mass dependence of dimuon production shows no nuclear dependence for 0.1 < x_t < 0.3, and a slight suppression below unity for heavy nuclei at x_t = 0.1.

Abstract

A precise measurement of the atomic-mass dependence of dimuon production induced by 800-GeV protons is reported. Over 450 000 muon pairs with dimuon mass M\ensuremath{\ge}4 GeV were recorded from targets of $^{2}\mathrm{H}$, C, Ca, Fe, and W. The ratio of dimuon yield per nucleon for nuclei versus $^{2}\mathrm{H}$, R=${\mathit{Y}}_{\mathit{A}}$/${\mathit{Y}}_{2\mathit{H}}$, is sensitive to modifications of the antiquark sea in nuclei. No nuclear dependence of this ratio is observed over the range of target-quark momentum fraction 0.1${\mathit{x}}_{\mathit{t}}$0.3. For ${\mathit{x}}_{\mathit{t}}$0.1 the ratio is slightly less than unity for the heavy nuclei. These results are compared with predictions of models of the European Muon Collaboration effect.