ProtonSpin · A look inside the proton: polarized transverse momentum dependent parton distributions for modern collider experiments

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Project objective

One of the big open challenges in contemporary particle physics is the quest for the three-dimensional structure of the proton, a principal building block of all visible matter. According to the theory of Quantum Chromodynamics, which is well-established since the mid-seventies, the proton is a composite particle built from elementary point-like particles known as quarks and gluons, or collectively 'partons'. A simple picture in which these quarks and gluons are quasi-free and move alongside their parent proton, is often very successful in describing experiments at particle colliders. However, this so-called 'collinear' framework is challenged in many experiments that are sensitive to the internal motion of the partons or to the spin degrees of freedom. Moreover, being strictly one-dimensional, it cannot account for some of the proton's main properties such as its spin, a long-standing and still unresolved problem known as the proton spin puzzle. Hence, in order to formulate an answer to such fundamental questions, it is necessary to explore the full three-dimensional structure of the proton. This structure needs to be extracted from experimental data, and can be encoded into so-called transverse momentum dependent parton distribution functions (TMDs). In this research project, I will study polarized TMDs, which are nowadays still very poorly known but are key to solve the aforementioned puzzles. For my study, I will capitalize on a new approach to TMD phenomenology, the Parton Branching method, as well as recent data from COMPASS at CERN, HERMES at DESY, and Hall A at JLab. This project is extremely timely, since the study of TMDs is a driving force behind several proposed new experiments in the US and in Europe, such as the recently approved Electron-Ion Collider.

Original text from CORDIS.

Participants

• UNIVERSITEIT ANTWERPEN · AntwerpenCoordinatorBelgium

Links

• View on CORDIS
• DOI: 10.3030/101032766