Collinear and Soft Gluon Corrections in Top Quark and Higgs Processes at the LHC and the Tevatron

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"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."Understanding and controlling the effects of QCD is crucial for performing precision tests of the standard model (SM) and detecting and identifying signals of new physics at hadron colliders. Perturbative QCD calculations are plagued by the dependence on the renormalization and factorization scales, resulting in uncertainties in the predictions of cross sections of typically O (100%) at leading order in the perturbation series in the strong coupling constant. To reduce the dependence on these arbitrary, unphysical parameters, QCD predictions need to include higher order corrections. The cross sections of the SM processes under consideration in this proposal are all known at next-to leading order (NLO) QCD (top-pair production, single top production) and next-to-next-to leading order (NNLO) QCD (Higgs production via gluon fusion). The PIs intend to further improve these calculations by including soft gluon resummation. The proposed calculations will further reduce the residual theoretical uncertainties due to the scale dependence, which is necessary in view of the envisioned experimental accuracy at the LHC. In the data analysis multi-purpose Monte Carlo (MC) generators such as Pythia and Herwig are well-used tools but providing improved predictions including higher-order corrections beyond the parton shower approach in form of a MC tool is still work in progress. The broader impacts are as follows: The proposed activities will play an important role in providing improved QCD predictions of a variety of processes in the SM and its supersymmetric extension that are crucial to fully exploit the physics potential of the LHC. Moreover, the calculational advancements in perturbative QCD developed as part of this project as well as the inclusion of soft resummation in Herwig++ will benefit the entire field of hadron collider phenomenology Dr. Kidonakis is already involving undergraduate students in his research activities. He plans to extend these activities by providing future teachers of Kennesaw's Master of Arts in Teaching program with a research experience in particle physics.