Study of Charged Hadron Multiplicity in Minimum Bias p+p Collisions at sqrt{s

The spectrum of charged hadrons in p+p interactions is an important observable as it provides information on particle production mechanisms. The measurement of the pseudorapidity distribution of charged hadrons provides essential information for QCD underlying events. In this summary, an analysis based on "two-hit tracks" of the charged hadron multiplicity is introduced for minimum bias \mbox{p+p} collisions at $\sqrt{s}= 900$ GeV and 10 TeV. The reconstruction algorithm using the hits from tracker barrel layers of the CMS detector is presented. The charged multiplicity spectrum can be reliably reproduced with a data sample of 50 $\mathrm{mb}^{-1}$ and the expected systematic uncertainty is at the 10\% level. \begin{center} \end{center}