Cluster Correlation in Mixed Models

We evaluate the dependence of the cluster correlation length r_c on the meanintercluster separation D_c, for three models with critical matter density,vanishing vacuum energy (Lambda = 0) and COBE normalized: a tilted CDM (tCDM)model (n=0.8) and two blue mixed models with two light massive neutrinosyielding Omega_h = 0.26 and 0.14 (MDM1 and MDM2, respectively). All modelsapproach the observational value of sigma_8 (and, henceforth, the observedcluster abundance) and are consistent with the observed abundance of DampedLyman_alpha systems. Mixed models have a motivation in recent results ofneutrino physics; they also agree with the observed value of the ratiosigma_8/sigma_25, yielding the spectral slope parameter Gamma, and nicely fitLCRS reconstructed spectra. We use parallel AP3M simulations, performed in awide box (side 360/h Mpc) and with high mass and distance resolution, enablingus to build artificial samples of clusters, whose total number and mass rangeallow to cover the same D_c interval inspected through APM and Abell clusterclustering data. We find that the tCDM model performs substantially better thann=1 critical density CDM models. Our main finding, however, is that mixedmodels provide a surprisingly good fit of cluster clustering data.Comment: 22 pages + 10 Postscript figures. Accepted for publication in Ap