Correlations in transverse momentum in pion-proton and kaon-proton collisions at 250 GeV/c

We have measured the second-order normalized differential factorial moments as a function of the difference of transverse momentum ($\Delta p_T$) in $\pi^{+} p$ and $K^+ p$ collisions at 250 GeV/$c$. The second-order differential factorial moments for like-charged pairs reveal a strong increase with decreasing $\Delta p_T$. In a small central rapidity window this increase is described by a simple power law. Such a behavior, if interpreted as originating from Bose-Einstein correlations, may indicate a structure of the transverse spatial distribution of the source similar to that recently predicted by Bia\l{}as and Peschanski for color-dipole emission in onium-onium scattering. The power of the rise obtained in the fit agrees with the predicted value.