A Precision Measurement of Charm Dimuon Production in Neutrino Interactions from the NOMAD Experiment

We present our new measurement of the cross-section for charm dimuon production in neutrino-iron interactions based upon the full statistics collected by the NOMAD experiment. After background subtraction we observe 15,344 charm dimuon events, providing the largest sample currently available. The analysis exploits the large inclusive charged current sample - about $9\times 10^6$ events after all analysis cuts - and the high resolution NOMAD detector to constrain the total systematic uncertainty on the ratio of charm dimuon to inclusive Charged Current (CC) cross-sections to $\sim 2%$. We also perform a fit to the NOMAD data to extract the charm production parameters and the strange quark sea content of the nucleon within the NLO QCD approximation. We obtain a value of $m_c(m_c)=1.159\pm0.075$ GeV/c$^2$ for the running mass of the charm quark in the $\bar{\rm MS}$ scheme and a strange quark sea suppression factor of $\kappa_s = 0.591 \pm 0.019$ at $Q^2=20$ GeV$^2$/c$^2$.