Pseudorapidity and leading transverse momentum distributions of charged particles in pp collisions at 8 TeV

The pseudorapidity and leading transverse momentum distributions of charged particles in proton-proton collisions at $\sqrt{s}$ = 8 TeV are measured in the pseudorapidity range $|\eta|<2.4$, by the CMS detector. The data correspond to an integrated luminosity of 17.4 nb$^{-1}$. Events were triggered by the TOTEM T2 telescopes that cover the pseudorapidity range $5.3<|\eta|<6.5$ for reconstructed tracks with $p_{T}>40$ MeV. The measurement of the pseudorapidity distributions was performed for primary charged particles with $p_T>0.1$ GeV and $p_T>1$ GeV, for two different conditions: an inclusive sample obtained by requiring tracks reconstructed in the acceptance of the TOTEM T2 telescopes in either hemisphere, and a sample enhanced in non-single diffractive dissociation events by requiring tracks in T2 in both forward and backward hemispheres. The $p_T$ distribution of the leading tracks in the central region is also measured. The distribution integrated over the leading track transverse momentum, above a $p_\rm{{T,min}}$ value, shows a transition from a steeply falling distribution at large $p_T$ (perturbative region) to a flat distribution at small $p_T$ (non-perturbative region) for $p_\rm{{T,min}}$ of a few GeV. This region is not well described by current Monte Carlo event generators.