An advanced approach for precision calculations of hard scattering processes at the LHC and future colliders using Parton Branching Transverse Momentum Distributions (PB-app)

• Applicant: Dr. Sara Taheri Monfared
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 467467041

The Standard Model of particle physics has been extremely successful in describing an overwhelming part of experimental results obtained in the past decades at highest energy particle colliders. Accurate calculation of QCD processes in proton-proton interactions at high energies remains to be one of the most challenging tasks in particle physics. The Large Hadron Collider (LHC) experiments, in particular, have provided a large number of very important measurements. These measurements require highest precision theory calculations, especially since new physics will most likely appear as small deviations of measurements from predictions. Progress in better understanding of QCD processes is essential for search of new physics at the LHC.In this proposal I address the assumptions which lower the precision of the predictions in case of collider predictions. One of the limitations of the mainstream approach is the neglect of transverse degrees of freedom in the proton. My proposal is based on the Parton Branching (PB) method developed in the last few years. The PB-app aims to improve the precision of calculations for processes at the LHC and future colliders by making use of the recently developed concept of transverse momentum dependent (TMD) parton densities, which adds a new physical dimension, the transverse momentum, to the factorization ansatz, often referred to as the 3-D image of the hadrons. This proposal is structured around three pillars: theoretical part, experimental part and publicly available part. In the first part of the project, the electroweak gauge boson TMD PDFs and TMD parton shower will be calculated. This will be achieved by theoretical development of the PB method, including fit strategy, and its immediate test in the measurements. Our approach will be then validated by comparing its predictions on Z/W+jet observables with traditional multijet merging method to check if they are consistent. In the experimental part of the project, high transverse momentum jets associated with Z/W bosons which come most likely from the shower will be measured within Open Data framework. This is the big advantage of the PB-app project that parton shower and TMD obtained in the theory part can be tested directly with Open Data. Within the PB-app project, we will combine different areas of pure theory/phenomenology with experimental Open Data analysis which is very efficient for educating purposes for people outside the experiment, mainly in developing countries. The outcome of my project will be extremely valuable for TMD physics and crucial for the precision measurements at the LHC, High Energy LHC (HE-LHC) and future collider experiments.

• DFG Programme: Research Grants
• International Connection: India, United Kingdom
• Cooperation Partners: Professorin Rohini Godbole; Dr. Francesco Hautmann