Nuclear dependence of charm production

Using data taken by SELEX during the 1996–1997 fixed target run at Fermilab, we study the production of charmed hadrons on copper and carbon targets with Σ − , p , π − , and π + beams. Parametrizing the dependence of the inclusive production cross section on the atomic number A as A α , we determine α for D + , D 0 , D s + , D + (2010), Λ c + , and their respective anti-particles, as a function of their transverse momentum p t and scaled longitudinal momentum x F . Within our statistics there is no dependence of α on x F for any charm species for the interval 0.1< x F <1.0. The average value of α for charm production by pion beams is α meson =0.850±0.028. This is somewhat larger than the corresponding average α baryon =0.755±0.016 for charm production by baryon beams ( Σ − , p ).