The spectra of strange hadrons are measured in proton-proton collisions, recorded by the CMS experiment at the CERN LHC, at centre-of-mass energies of 0.9 and 7 TeV. The K0_s, Lambda, and Xi-̂ particles and their antiparticles are reconstructed from their decay topologies and the production rates are measured as functions of rapidity and transverse momentum. The results are compared to other experiments and to predictions of the PYTHIA Monte Carlo program. The transverse momentum distributions are found to differ substantially from the PYTHIA results and the production rates exceed the predictions by up to a factor of three.

Measurements are presented of the production of primary K(S)0 and Lambda particles in proton-proton collisions at sqrt(s) = 7 TeV in the region transverse to the leading charged-particle jet in each event. The average multiplicity and average scalar transverse momentum sum of K(S)0 and Lambda particles measured at pseudorapidities abs(eta)

Experimental results on a search for charmed particle production in proton-proton collisions at the center of mass energy (.sqrt.s) of 53 GeV are presented. Evidence of cidences, a signature of charmed particle production, was sought. The inclusive e/.pi. ratio was measured with a magnetic spectrometer located at 32° from Beam 1 of Intersection I6 of the CERN Intersecting Storage Rings (ISR). The e/.pi. ratio from direct (unknown) sources was found to rise from 1.06 x 10−4 at p/sub perpendicular to/ = 1.5 GeV/c to 5.53 x 10−4 at p/sub perpendicular to/ = 0.25 GeV/c. One possible source for this signal is the semi-leptonic decay of charmed particles (e.g., D .-->. K° e.nu.). If so, then electron-strange particle (e.g., .lambda.°, K°) coincidences are expected. The charged decay products of .lambda.° and K° were detected in a multiparticle spectrometer surrounding Beam 1 downstream of the intersection. To determine if there is an electron-strange particle correlation, the number of .lambda.°'s (K°'s) in coincidence with an electron in the 32° spectrometer was compared with the number of .lambda.'s (K°'s) in coincidence with a hadron in the same kinematic range. No evidence for an enhanced production of strange particles with electrons relative to hadrons was found. However, given the acceptance of the apparatus, the absence of a signal is consistent with current models of charmed particle production and decay. 40 references, 51 figures, 20 tables.

The associated production of a W boson and a single charm quark (W+c) is the only process in proton-proton collisions that directly probes the strange quark content of the proton. In this thesis, W+charm production is measured in proton-proton collisions at the LHC at 13 TeV, as recorded by the Compact Muon Solenoid (CMS) experiment. The analysis focuses on the identification of W bosons in their leptonic decay to a muon and a neutrino and charm quarks are tagged via the full reconstruction of D*-Mesons. The measured cross sections of W+c production are used, in combination with other relevant CMS results and the most precise HERA DIS data, in a QCD analysis to determine the strange quark content of the proton. The resulting strange quark distribution and suppression, with respect to the other light sea quarks, are in good agreement with those obtained in neutrino scattering experiments and extend their kinematic reach.