Higher order QCD calculations for collider phenomenology

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In most collisions measured at the Large Hadron Collider (LHC) at CERN, a very large number of particles are produced. However, for a special class of events, so-called exclusive events, this is not the case. This can happen if the underlying hard scattering occurs through colour neutral exchanges, like photons or systems of gluons in the colour singlet state. To better understand these events, higher order calculations are required. Recently such work has been done (in part in Liverpool) for the special case of vector meson photo-production, and subsequently measurements at the LHCb have confirmed the predictions. The proposed research project is to perform calculations for the more complicated case of open quark (or jet) production, and possibly to electro-production or processes including W, Z or Higgs bosons. This will not only lead to a deeper understand of the strong interaction and to better constrain the parton distributions functions of the proton (and heavy ions), but will also provide search channels for physics beyond the Standard Model (SM) of particle physics.A second possible project, already discussed with Chris Flett, is to participate in fourth-order calculations in perturbative QCD, performed by the ERC group of Jos Vermaseren at NIKHEF (Amsterdam) together with Andreas Vogt in Liverpool who will be the second supervisor. The main thrust of these calculations, which are at the cutting edge of symbolic computation in theoretical high-energy physics, is to constrain and ultimately calculate the next-to-next-to-next-to-leading order (NNNLO) splitting functions for the scale dependence of the quark and gluon distributions in the proton. NNNLO calculations are required, for example, for the cross section for Higgs production at the LHC at CERN, and for the best possible determination of the strong coupling constant which is one of the fundamental parameters of the SM.