The research programme of the Glasgow Nuclear Physics Group focuses on the study of the strong interaction. As one of the four fundamental forces in nature, the strong force is responsible for the formation and stability of atomic nuclei. At an even more fundamental level it also is the interaction that forms hadrons from quarks and gluons and is therefore responsible for most of the observable mass in the universe. Quantum Chromodynamics (QCD) is widely accepted as the fundamental theory describing the strong interaction; a recent Nobel Prize (2004, Gross, Politzer, Wilczek) was awarded for developing this theory. QCD has some features that make it very different from the theories of the electromagnetic and weak interactions. Only very high energy particle physics processes can easily be calculated pertubatively, a feature known as asymptotic freedom At lower energies, effective field theories incorporating some of the fundamental symmetries of QCD, e.g. chiral symmetry, can be applied. In addition, models such as the quark model have been developed, which describes strongly interacting particles as either three-quark or quark-antiquark systems. In our research we use scattering experiments to investigate the structure of nuclei and nucleons as well as spectroscopic methods for nucleon resonances and hadrons. Both approaches complement each other. We carry our experiments out at leading accelerator facilities in Europe and the US: MAX-lab in Lund, Sweden; MAMI in Mainz, Germany; Jefferson Lab in Newport News, USA; DESY in Hamburg, Germany and FAIR in Darmstadt, Germany. In these experiments we use (often polarised) beams of electrons, photons and also (in the future) anti-protons. Our research is organised into four programmes or themes: - Short-range Nuclear Structure We want to understand how the constituents of atomic nuclei, protons and neutrons (collectively known as nucleons), interact with each other to give rise to a wide range of phenomena. In particular we plan to investigate, what happens when nucleons pass very close to each other in collisions within a nucleus, the strength of interactions involving 3 nucleons and how the nuclear medium affects particles that are created within it. - Nucleon Structure Knowing that nucleons are themselves composite objects made up of more fundamental entities (quarks and gluons), we need to establish the distribution of matter within them. Form factors and parton distribution functions are used to describe the structure of nucleons. In recent years the theoretical framework of Generalised Parton Distributions (GPDs) has been developed that ties the description of nucleon structure systematically together. Once measured, GPDs will give us a 3-dimensional picture of the nucleon as well as a way to access the total angular momentum of quarks inside a nucleon. - Nucleon Resonance Spectroscopy As composite objects, nucleons can be excited to higher mass states. Whilst the quark model describes a great deal of the excitation spectrum, several predictions must be confirmed to clarify which variant of the quark model most accurately describes reality. Hunting for predicted states is a very difficult task, and will involve, amongst other techniques, the use of polarised high energy photons similar to the way in which optical polarisation can be employed to see greater detail. - New Forms of Hadronic Matter The observation of states beyond the quark model is of fundamental importance in answering the question of why quarks and gluons have never been observed in isolation, even though there is compelling evidence that they must exist. This feature, known as 'confinement', is unique to the strong interaction, and is not observed in any of the other fundamental forces of nature. We use methods of hadron spectroscopy to search for so-called glueballs and exotic hybrid mesons.

The overarching goal of our research programme is to address aspects of the broad science challenge: "What are the basic constituents of matter and how do they interact?". In particular, by performing experiments primarily with electron and photon beams, we study questions such as "How do quarks and gluons form hadrons?", and by studying these basic, strongly-interacting building blocks we are able to tackle the question "What is the nature of nuclear matter?"

Approximately 98% of the mass of nucleons, and therefore of the visible universe, emerges from the interactions among their constituents, the quarks and gluons. The Higgs mechanism, which gives mass to the bare quarks, is responsible for only a small fraction of the nucleon mass. The confinement of quarks within mesons and baryons is a direct consequence of their fundamental interactions. The field theory of the strong nuclear force, Quantum Chromodynamics (QCD), is now well established, and yet the phenomena described above cannot be understood from the QCD Lagrangian; they are emergent properties that arise from the unique complexity of these interactions. QCD is as yet intractable at the mass scale of nucleons and nuclei, so a clear picture of the fundamental nature of matter at these energies does not yet exist. However, this situation is set to change, and both theoretical and experimental developments in the coming decade are expected to revolutionise our understanding of nuclear matter within the context of QCD and the Standard Model. We have an ambitious plan of work that encompasses the development of research programmes from existing themes, possibilities for new physics measurements that have opened up recently, and the completion of physics projects from data that has been previously obtained. Our programme will build on the work of our previous consolidated grant and we will exploit the investment in manpower and equipment to address the current issues in our field at the highest possible level, at the world's top facilities. The challenges for the science programme are encapsulated by several key questions, which we group together as they roughly match the themes we have defined: * What is the mechanism for confining quarks and gluons in strongly interacting particles (hadrons)? * What is the structure of the proton and neutron, and how do hadrons get their mass and spin? * Can we understand the excitation spectra of hadrons from the quark-quark interaction? * Do exotic hadrons (multiquark states, hybrid mesons and glueballs) exist? * How do nuclear forces arise from QCD? * What is the equation of state of nuclear matter? * What is the nature of dark matter? We will address these questions by leading experimental programmes at two of the world's leading facilities: * Jefferson Lab, Newport News, Virginia, USA (JLab) * MAMI, Mainz, Germany:

Approximately 98% of the mass of nucleons, and therefore of the visible universe, emerges from the interactions among their constituents, the quarks and gluons. The Higgs mechanism, which gives mass to the bare quarks, is responsible for only a small fraction of the nucleon mass. The confinement of quarks within mesons and baryons is a direct consequence of their fundamental interactions. The field theory of the strong nuclear force, Quantum Chromodynamics (QCD), is now well established, and yet the phenomena described above cannot be understood from the QCD Lagrangian; they are emergent properties that arise from the unique complexity of these interactions. QCD is as yet intractable at the mass scale of nucleons and nuclei, so a clear picture of the fundamental nature of matter at these energies does not yet exist. However, this situation is set to change, and both theoretical and experimental developments in the coming decade are expected to revolutionise our understanding of nuclear matter within the context of QCD and the Standard Model. There are several key questions that will be addressed by the work proposed here: * What is the mechanism for confining quarks and gluons in strongly interacting particles (hadrons)? * What is the structure of the proton and neutron and how do hadrons get their mass and spin? * Can we understand the excitation spectra of hadrons from the quark-quark interaction? * Do exotic hadrons (multiquark states, hybrid mesons and glueballs) exist? * How do nuclear forces arise from QCD? * Can nuclei be described in terms of our understanding of the underlying fundamental interactions? The scientific vision behind the upgrade to the Thomas Jefferson National Accelerator Facility (JLab) in Newport News, Virginia, is to address fundamental issues such as how constituent quarks acquire mass, and why they are confined. It is therefore ideally suited to tackling the pivotal questions laid out above. New insights into the fundamental structure of the nucleon will be obtained from measurements of nucleon form factors, Generalised Parton Distributions (GPDs) and Transverse Momentum-dependent parton Distributions (TMDs). The fundamental nature of QCD confinement will be studied through the investigation of the light hadron spectrum, and the search for the existence of exotic states, in which the confining gluonic field provides an additional degree of freedom to the quarks. These states are a direct prediction of the QCD theory but remain unobserved experimentally. The Jefferson Lab 12 GeV Upgrade offers an exciting opportunity for the UK Nuclear Physics community to lead and instigate world-leading hadron physics research. The central scientific motivation for undertaking this project is a continuing desire to understand QCD physics: to obtain new information on the structure of nucleons, and to investigate the mechanism of quark confinement. This proposal represents a bid by the Edinburgh and Glasgow nuclear physics groups to build on established leadership roles, and enhance their impact on JLab's future science programme for the coming decades.

All of biology -- life itself -- depends on enzymes. Enzymes are large, natural molecules that allow specific biochemical reactions to take place quickly, that is to say enzymes are natural catalysts. They are very good catalysts, but as yet we do not understand what it is that makes them such good natural chemists. There are many reasons for studying enzymes and the reactions they catalyse: many drugs are enzyme inhibitors (they stop specific enzymes from working), so better understanding of enzymes will help in the design of new drugs. Better understanding of individual enzymes should also help understand and predict the effects of genetic variation, for example in understanding why some people may benefit from a particular drug, or may be at risk from a disease. Enzymes are also very good and environmentally catalysts - knowing how they function should help in the design and development of new 'green' catalysts for forensic, synthetic, analytical and biotechnological applications. Enzymes also show great promise as 'molecular machines' in the emerging field of nanotechnology. We will carry out a collaborative project based on experimental physics that supports existing research programmes at the international leading edge in providing a physical description of how enzymes work. We will focus on an enzyme whose reaction involves the transfer of hydrogen. Recent experimental work has shown that these reactions involve the quantum mechanical phenomenon of tunnelling, whereby hydrogen (because it is very light) is transferred from one molecule to another by going through the energy barrier, instead of over it. This might at first seem esoteric, but it seems that quantum tunnelling is essential in making enzyme reactions fast. Experimental results also suggest that the complex motions of large enzyme molecules may be crucial in helping tunnelling to happen within them. It seems that enzymes may have evolved specifically to make use of quantum tunnelling, and that this may be crucial in understanding how they function. Current computer modelling methods are very useful for studying aspects of enzyme reactions - making molecular 'movies' of how enzymes work - but modelling molecular motions in enzymes is particularly challenging. In this proposal, we will develop state-of-the-art methods based on emerging high power light sources to investigate the role of these motions in making enzymes work. The new methods we develop will pave the way for other researchers to also unravel the origin of the catalytic power of enzymes. The results should provide new and exciting insight into how enzymes function.