Towards Global Interpretation of LHC Data

This book presents the first global interpretation of measurements of jet and top quark production at the Large Hadron Collider, including a simultaneous extraction of the standard model parameters together with constraints on new physics, unbiased from the assumptions on the standard model parameters. As a long-standing problem, any hadron collider search for new physics depends on parton distribution functions, which cannot be predicted but are extracted experimentally. However, performing the extraction in the same kinematic region where physics beyond the standard model is expected to manifest causes the risk of absorbing the new physics effects into the parton distributions. In this book, the issue is addressed by extending the standard model by effective contributions from quark contact interactions describing new physics and extracting the parton distributions and standard model parameters simultaneously with setting limits on the contact interactions. In the process, the most precise single measurement of the strong coupling constant at the LHC is performed, to date. Furthermore, the book details the first investigation of the mass renormalization scale dependence of the top quark mass, highlighting the importance of a proper scale choice for obtaining robust predictions and improving the precision of experimental analyses. The initial chapters provide the reader with a succinct yet accessible introduction to the relevant theoretical and experimental topics. The presented investigations are at the edge of precision in the phenomenology of high-energy physics and serve to pave the road toward a global interpretation of LHC data.

Results in the most precise extraction of the strong coupling constant at a hadron collider Presents an unbiased strategy for the simultaneous extraction of standard model and new physics parameters Details the first investigation of the mass renormalization scale dependence of the top quark mass

Auteur
Dr. T. Mäkelä is a research scholar working in the phenomenology of high-energy physics, at the intersection of theory and experiment. His work serves to both improve our understanding of the standard model of particle physics via increased precision and to investigate the possibilities for new physics beyond the standard model. During his doctoral studies at DESY in Hamburg, Germany, Dr. Mäkelä worked as a theorist associated with the CMS experiment. The main focus of this work is on an unbiased strategy for the simultaneous extraction of the fundamental parameters of the standard model, together with the couplings of new physics. This is performed for the first time at the Large Hadron Collider and results in the most precise extraction of the strong coupling constant at a hadron collider, at the time of writing. Furthermore, Dr. Mäkelä has carried out the first consistent investigation of the mass renormalization scale dependence of the mass of the top quark, demonstrating the importance of a proper scale choice for stabilizing the theoretical predictions for top quark-antiquark pair production cross sections, hence increasing the precision of experimental analyses.

The results of the pioneering work have been highlighted by CERN and DESY. They have also been presented at major conferences in the field of high-energy physics, as well as invited seminar talks.

Contenu

1. Introduction.- 2. The role of jets and the top quark in the Standard Model.- 3. Effective field theory.- 4. LHC measurements.- 5. Extraction of the top quark MSR mass using CMS data.- 6. The xFitter QCD anaylsis framework.- 7. Interpretation of CMS measurements in terms of SM parameters and search for new physics.- 8. Summary and conclusions.- Appendix A: NNLO QCD analysis with the k-factor approach.