Measurements of Hadron Production and Underlying Event Studies at CMS

We report on measurements of hadron production, studies of underlying event and forward processes in $pp$ collisions at $\sqrt{s}=$ 0.9, 2.36, and 7\,TeV, recorded with the CMS detector. Transverse momentum, pseudorapidity and multiplicity distributions of charged hadrons are presented. For non-single diffractive collisions, the average charged-hadron transverse momentum and pseudorapidity density near mid-rapidity are compared with other measurements in $p \bar p$ and $pp$ collisions. In order to extend the statistical reach of the measurement of charged hadron transverse momentum spectra, jet triggers are employed to enhance yields at high p$_{T}$. Measured spectra of identified strange hadrons, reconstructed based on their decay topology, are also shown. The underlying event is studied by measuring the charged multiplicity density and the charged energy density in a region perpendicular to the plane of the hard 2-to-2 scattering. The study allows to discriminate among various QCD Monte Carlo models with different multiple parton interaction schemes. In addition, we present the measurement of the underlying event using the jet-area/median approach.