Theoretical nuclear physics

我们计划对核物理学中当前感兴趣的各种主题进行理论研究。这些涵盖了能量尺度的全部范围，从低能量的原子核结构，到重原子核之间相对论性碰撞产生的致密、强烈相互作用的物质。我们的工作将遵循三个主题：使用微观多体方法从第一原理计算重核的结构;使用有效场论结合量子色动力学的对称性来研究核子和其他强子的性质和相互作用;改进夸克模型的发展来探索致密物质中可能的相变。我们将发展一个版本的耦合团簇方法，并应用它来计算重核的结构。基本方法是一种已广泛应用于其他领域的方法，例如量子化学。对于核物理学，我们需要一个能始终如一地处理核子-核子势的强排斥核心的版本。我们打算将其实现为可以分发用于一般用途的计算机代码。我们将使用这些结果来计算实验感兴趣的原子核的性质，特别是远离稳定线的同位素。在强子物理领域，我们将进一步发展强子性质和相互作用的有效场论。这些都是基于手征对称性，反映了QCD中几乎无质量的夸克的存在。一个特别的焦点将是描述核子对外部场的响应的极化率。我们计划从氘和He-3上的光子散射数据确定中子的电磁极化率。我们也将扩展到其他的，自旋相关的极化率和虚光子，这可以从电子散射过程中提取的相关量。我们还将使用重整化群来分析核力对相关能量标度的依赖性，从而构建更有效的描述三体力的理论。相对论夸克模型将被开发用于稠密的、强相互作用的物质。我们将研究这些与援助的功能renormalisation组，一个强大的技术，已被用于研究相变在其他领域。我们打算探索夸克物质的相图，这是预期包含不同模式的对称性，如恢复明显的手征对称性和超导的各种形式的外观相位之间的过渡。这些模型也可以扩展到包括夸克之间的三体力，这将使我们能够研究由核子组成的正常核物质与夸克物质之间的跃迁。

We plan to carry out theoretical investigations on a variety of topics of current interest in nuclear physics. These cover the full range of energy scales, from the structure of nuclei at low energies, to the dense, strongly interacting matter produced in relativistic collisions between heavy nuclei. Our work will follow three main themes: the use of microscopic many-body methods to calculate the structure of heavy nuclei from first principles; the use of effective field theories incorporating the symmetries of quantum chromodynamics to study the properties and interactions of nucleons and other hadrons; the development of improved quark models to explore the possible phase transitions in dense matter. We will develop a version of the coupled-cluster method and apply it to calculate the structure of heavy nuclei. The basic method is one that has been widely used in other fields, for example quantum chemistry. For nuclear physics we need a version that can handle consistently the strongly repulsive core of the nucleon-nucleon potential. We intend to implement this as a computer code that can be distributed for general use. We will use the results to calculate properties of nuclei of experimental interest, in particular isotopes that lie far from the line of stability. In the area of hadron physics, we will further develop effective field theories for hadron properties and interactions. These are based on the chiral symmetry that reflects the presence of nearly massless quarks in QCD. A particular focus will be the polarisabilities that describe the responses of nucleons to external fields. We plan to determine the electromagnetic polarisabilities of the neutron from data on photon scattering on deuterium and He-3. We will also extend this to other, spin-dependent polarisabilities and to related quantities for virtual photons, which can be extracted from electron scattering processes. We will also use the renormalisation group to analyse the dependence of nuclear forces on the relevant energy scales, and hence to construct better effective theories describing three-body forces. Relativistic quark models will be developed for dense, strongly interacting matter. We will study these with the aid of the functional renormalisation group, a powerful technique which has been used to study phase transitions in other fields. We intend to explore the phase diagram of quark matter, which is expected to contain transitions between phases with different patterns of symmetries such as restoration of manifest chiral symmetry and the appearance of various forms of superconductivity. These models can also be extended to include three-body forces between the quarks and these will allow us to study the transition between normal nuclear matter, consisting of nucleons, and quark matter.