QCD Physics from CMS

CMS is pursuing a rich program of QCD physics. Initial data collected in $2009$ at both $900$ GeV and $2.36$ TeV has been used for commissioning the detector and for the first measurements of charged hadron pseudorapidity and transverse momentum distributions as well as Bose-Einstein correlations. These first results from CMS at the new energy frontier accessible at the LHC are presented. For non-single-diffractive interactions, the average charged-hadron transverse momentum is measured to be $0.46$ $\pm$ $0.01$ (stat.) $\pm$ $0.01$ (syst.) GeV/${\it c}$ at $0.9$ TeV and $0.50$ $\pm$ $0.01$ (stat.) $\pm$ $0.01$ (syst.) GeV/${\it c}$ at $2.36$ TeV, for pseudorapidities between $-2.4$ and $+2.4$. At these energies, the measured pseudorapidity densities in the central region, $dN_{\rm ch}/d\etaI_{I\etaI<0.5}$, are $3.48$ $\pm$ $0.02$ (stat.) $\pm$ $0.13$ (syst.) and $4.47$ $\pm$ $0.04$ (stat.) $\pm$ $0.16$ (syst.), respectively. The results at $0.9$ TeV are in agreement with previous measurements and confirm the expectation of near equal hadron production in $p\bar{p}$ and $pp$ collisions. The measured strength and effective size (using exponential parametrization) of the Bose-Einstein correlation are $\lambda = 0.625 \pm 0.021$ (stat.) $\pm$ $0.046$ (syst.) and $r = 1.59 \pm 0.05$ (stat.) $\pm$ $0.19$ (syst.) fm at $0.9$ TeV; $\lambda = 0.663 \pm 0.073$ (stat.) $\pm$ $0.048$ (syst.) and $r = 1.99 \pm 0.18$ (stat.) $\pm$ $0.24$ (syst.) fm at $2.36$ TeV.