The asymmetry in the production cross-section σ of D± mesons,
AP = σ(D+) − σ(D−)
σ(D+) + σ(D−)
,
is measured in bins of pseudorapidity η and transverse momentum pT within the acceptance of the LHCb
detector. The result is obtained with a sample of D+ → K0
Sπ+ decays corresponding to an integrated
luminosity of 1.0 fb−1, collected in pp collisions at a centre of mass energy of 7 TeV at the Large
Hadron Collider. When integrated over the kinematic range 2.0 < pT < 18.0 GeV/c and 2.20 < η < 4.75,
the production asymmetry is AP = (−0.96 ± 0.26 ± 0.18)%. The uncertainties quoted are statistical and
systematic, respectively. The result assumes that any direct CP violation in the D+ → K0
Sπ+ decay is
negligible. No significant dependence on η or pT is observed.