Abstract
This thesis investigates integrated and differential leadingorder crosssections for the production of weak bosons with up to two associated jets and leptonic decays at hadron colliders, i.e. pp/ppbar → (W− → l− νbar ) + n jets, pp/ppbar → (W+ → l+ ν ) + n jets, pp/ppbar → (Z → l− l+) + n jets and pp/ppbar → (Z → sum ν νbar ) + n jets. All crosssections are calculated for accelerator setups Tevatron Run II, LHC with 7 TeV and 14 TeV, and PDF sets MSTW2008LO (90% C.L.) and CTEQ6L1. In all cases three different scale choices, static μ0 = MV , dynamic ET and HT , with a variation by a factor of four have been considered. Additionally, PDF uncertainties have been determined for the MSTW2008LO results. All results have been calculated using an amended version of the
MCFM 6.0 package and custom Python scripts.
The ratio between the integrated crosssections for W+ and W− production with leptonic decay and the ratio between the integrated crosssections for the two studied decays of the Z production have been calculated. I find that both are very stable for all scale choices. In contrast, for the BerendsGiele scaling a dependence on the choice of static/dynamic scale was observed.
Furthermore a variety of differential crosssections have been calculated. This includes transverse momentum p_T and rapidity y for charged leptons and jets, missing transverse momentum p_T,miss , rapidity separation ∆y, separation in transverse angle ∆φ and ∆R. The distance observables use pT ordered jets, charged leptons and missing momentum. For zerojet processes the PDF and scale uncertainties decrease in the large invariant mass tails and for one and twojet processes the uncertainties become larger in the tails. The latter was also observed for transverse momentum distributions.
The differential crosssections are compared for the different scales and I find that different choices do not change the position of peaks or general features of the curves, but tails can differ. I show that varying the static scale by a factor of four is not always sufficient to cover the central values for dynamic scale choices. For invariant mass distributions, I show that the dynamic scale results are smaller than the static scale predictions and normally fall within the uncertainty envelope. Further, rapidity distributions are very stable with respect to different scale choices and only differ by a constant factor. The dynamic scales are well within the uncertainty envelope of the static scale. Comparisons with respect to different PDF sets showed a simple scaling for transverse observables.
The PDF uncertainties for MSTW2008LO (90% C.L.) were large enough to encompass the deviation between the two studied PDF sets for zero and onejet processes, but not for two associated jets. For rapidity distributions, no uniform behaviour of CTEQ6L1 versus MSTW2008LO was observed. CTEQ6L1 can give a larger crosssection in the central/forward region, and the MSTW2008LO error underestimated this deviation.
MCFM 6.0 package and custom Python scripts.
The ratio between the integrated crosssections for W+ and W− production with leptonic decay and the ratio between the integrated crosssections for the two studied decays of the Z production have been calculated. I find that both are very stable for all scale choices. In contrast, for the BerendsGiele scaling a dependence on the choice of static/dynamic scale was observed.
Furthermore a variety of differential crosssections have been calculated. This includes transverse momentum p_T and rapidity y for charged leptons and jets, missing transverse momentum p_T,miss , rapidity separation ∆y, separation in transverse angle ∆φ and ∆R. The distance observables use pT ordered jets, charged leptons and missing momentum. For zerojet processes the PDF and scale uncertainties decrease in the large invariant mass tails and for one and twojet processes the uncertainties become larger in the tails. The latter was also observed for transverse momentum distributions.
The differential crosssections are compared for the different scales and I find that different choices do not change the position of peaks or general features of the curves, but tails can differ. I show that varying the static scale by a factor of four is not always sufficient to cover the central values for dynamic scale choices. For invariant mass distributions, I show that the dynamic scale results are smaller than the static scale predictions and normally fall within the uncertainty envelope. Further, rapidity distributions are very stable with respect to different scale choices and only differ by a constant factor. The dynamic scales are well within the uncertainty envelope of the static scale. Comparisons with respect to different PDF sets showed a simple scaling for transverse observables.
The PDF uncertainties for MSTW2008LO (90% C.L.) were large enough to encompass the deviation between the two studied PDF sets for zero and onejet processes, but not for two associated jets. For rapidity distributions, no uniform behaviour of CTEQ6L1 versus MSTW2008LO was observed. CTEQ6L1 can give a larger crosssection in the central/forward region, and the MSTW2008LO error underestimated this deviation.
Original language  English 

Qualification  MPhil 
Awarding Institution 

Supervisors/Advisors 

Award date  1 Jun 2013 
Publication status  Unpublished  2013 
Keywords
 particle, physics, phenomenology, nature, vector boson, weak boson, W boson, Z boson, jet, jets, Tevatron, DZero, CDF, CERN, ATLAS, CMS, LHC, QFT, QCD, QED, Standard Model, SM, Monte Carlo, MC, scale uncertainties, PDF uncertainties, MCFM, errors, dissertation, thesis