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The aim of this thesis is to present a new Monte-Carlo simulation of double parton scattering (DPS) named dShower. DPS is the process where two separate parton-parton interactions happen in a single proton-proton collision and constitutes an important background signal to numerous processes of interest such as diboson pair production or four-jet production. An accurate modelling of DPS requires to account for the correlations between the partons belonging to the same proton. In particular, it is necessary to take into account the fact that two partons may have a common origin in a single parton due to the so-called "one-to-two" perturbative splitting mechanism. Including this splitting effect is a cumbersome task since it leads to a potential double counting with single parton scattering (SPS). Indeed, a DPS process where a one-to-two splitting happens in each proton can be seen as a loop correction to SPS. The dShower simulation introduced in this thesis allows the user to generate parton-level DPS events. The two hard scatters are sampled according to the full DPS cross section and are evolved simultaneously with a parton shower. In the algorithm, the one-to-two splitting mechanism is included in a consistent manner. DPS and SPS events can also be combined in the simulation without double counting. Some numerical results for same-sign WW and ZZ pair production are presented in the thesis.

Adsorption of polymers in solutions on surfaces depends on a variety of factors such as polymer-surface interaction strength, properties of the surface, temperature, length of polymer chains, and the quality of solvents. For adsorption to occur, the gain in energy by adsorbing onto a surface should be greater than the loss in conformation entropy of the polymer chain arising due to binding to the surface. Polymer adsorption on flat surfaces have been widely studied and well understood. However, polymer adsorption on rough surfaces is less understood due to the complexity involved in equilibration and sampling of such systems. The main goal of this study was to elucidate clearly the effect of surface roughness on adsorption of polymers.Molecular simulations techniques are employed to investigate the effect of surface roughness on polymer adsorption. Both Monte-Carlo simulations and molecular dynamics simulations are used to study the effects of irregular (self-affine) roughness and regular (uniform) roughness parameters, respectively. The Monte-Carlo simulations are carried out in the NVT ensemble. The adsorbed polymers are characterized by density and bond orientation profiles, adsorbed monomer fraction and chain topologies. The results of this study elucidate the extent to which adsorption or desorption can be controlled solely by tuning surface roughness parameters. In particular, the results from molecular dynamics study show that increasing surface roughness enhances polymer adsorption. However, the results from Monte-Carlo study are markedly different; the effect of surface roughness is to diminish the fraction of monomers adsorbed. This trend was observed as a result of using a wide range of chain population distribution in the study.