D∗ and D meson production in muon nucleon interactions at 160 GeV/c

The production of D ∗ and D mesons in inelastic scattering of 160 GeV/c muons off a 6LiD target has been investigated with the COMPASS spectrometer at CERN for 0.003 (GeV/c)2<Q 2<10 (GeV/c)2 and 3×10−5<x Bj <0.1. The study is based on 8100 events where a D 0 or $\bar{D}^{0}$ is detected subsequently to a D ∗+ or D ∗− decay, and on 34000 events, where only a D 0 or $\bar{D}^{0}$ is detected. Kinematic distributions of D ∗, D and $K_{2}^{*} (1430)$ are given as a function of their energy E, transverse momentum p T , energy fraction z, and of the virtual photon variables ν, Q 2 and x Bj . Semi-inclusive differential D ∗ production cross-sections are compared with theoretical predictions for D ∗ production via photon–gluon fusion into open charm. The total observed production cross-section for D ∗± mesons with laboratory energies between 22 and 86 GeV is (1.9±0.4) nb. Significant cross-section asymmetries are observed between D ∗+ and D ∗− production for ν<40 GeV and z>0.6.