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Details of Grant 

EPSRC Reference: EP/C013646/1
Title: Effective field theories and few-body physics
Principal Investigator: Al-Khalili, Professor J
Other Investigators:
Zhao, Professor Q
Researcher Co-Investigators:
Project Partners:
Department: Department of Physics
Organisation: University of Surrey
Scheme: Standard Research (Pre-FEC)
Starts: 14 March 2005 Ends: 13 September 2005 Value (£): 24,844
EPSRC Research Topic Classifications:
Nuclear Structure
EPSRC Industrial Sector Classifications:
No relevance to Underpinning Sectors
Related Grants:
Panel History:  
Summary on Grant Application Form
More often than not, any given physical system - whether it is our planet or a single atomic nucleus - can be described in very different ways, depending on the features we are interested in and the level of detail we require. Usually, the different levels of description will require quite different theories and apply at different scales (of complexity, size or energy). Of course, one can argue that the ultimate aim of science is to describe everything using the most fundamental theory that takes into account the minutest features and most elemental building blocks, from which all other properties emerge. When trying to construct a theory, which spans all such scales, traditional methods of physics can therefore be difficult to apply. The physics of atomic nuclei is certainly a case in point. It appears radically different at different energy scales. Effective field theory (EFT) is a theoretical prescription for constructing theories spanning multiple energy scales. Rather than stumbling on this obstacle, however, EFT provides a method to use the physical difference between energy regimes to advantage. Traditional nuclear physics problems can be addressed using two seemingly different physical pictures. On the one hand, the consensus of the majority of the nuclear-physics community holds that nuclei are made up of protons and neutrons, collectively called nucleons, that interact via the nuclear force, each pair at a time, and that to a large extent does not distinguish between the protons and neutrons other than by the fact that protons carry (positive) electric charge while the neutrons are electrically neutral.By contrast, the more fundamental theory of the nucleus is known as quantum chromodynamics (or QCD). In this picture the nucleons are themselves made up of more fundamental particles: the quarks, and many more complicated effects are taken into account such as the correct treatment of the way they behave according to Einstein's theory of relativity and the interaction of many quarks with each other at once, instead of just two at a time. However, it is incredibly difficult to apply QCD to a system as complex as a whole nucleus. Clearly, it is not straightforward to merge these two extraordinarily different pictures of nuclei, and the root of the problem must lie in the difference of energy scales.EFT is thus applicable in situations where we wish to understand the physics at some low-energy scale as the limiting case of a more general problem whose full features are apparent only at some higher energy. Inside the atomic nucleus therefore, EFT is a technique for using the 'effective' degrees of freedom apparent at low energy (the nucleons) instead of the more fundamental ones (the quarks and gluons). It has developed rapidly over the past decade to become a hot topic and an area of active research in nuclear theory around the world. The motivation of the work in this proposal is to apply EFT to simple nuclei consisting of just a few nucleons, such as the deuteron, which consists of just a proton and a neutron, and the triton, which has a proton and two neutrons. Both these nuclei are well established as being good test cases for studying atomic nuclei. We will study reactions involving these nuclei with probes such as photons and mesons.
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Organisation Website: http://www.surrey.ac.uk