Nucleon-Number Dependence of Inclusive Dihadron Production in Proton-Nucleus Collisions at 400 GeV/c

We have measured the nucleon-number ($A$) dependence of hadron-pair production in 400-GeV/c proton-nucleus collisions, using Pb and Be targets. Charged-hadron pairs were observed near rapidity $y_{\mathrm{c}.\mathrm{m}.\mathrm{}}=-0.4\mathrm{}$ with $\Delta \varphi \cong 180°$. The $A$-dependence exponent rises from 1.1 to 1.2 in the range $2.0<~\left|p_{{\perp }_1}\mathrm{}\right|+\left|\mathrm{}{p}_{{\perp }_2}\right|<~4.5$ GeV/c. The dihadron $p_{\perp }$ correlation function is significantly smaller for Pb than for Be.