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First order phase transitions beyond the Standard Model

超越标准模型的一阶相变

基本信息

批准号：
2131876
负责人：
金额：
--
依托单位：
University of Sussex
依托单位国家：
英国
项目类别：
Studentship
财政年份：
2018
资助国家：
英国
起止时间：
2018 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=studentship-2131876
关键词：
First order phase transitions beyond

项目摘要

The direct detection of gravitational waves by the LIGO/Virgo collaboration shows that a new window on theUniverse is now open, with the potential to revolutionise our knowledge of its history. Equally, the discoveryof the Higgs particle at the Large Hadron Collider (LHC) has triggered a hunt for a complete understanding ofthe origin of elementary particle masses. These most fundamental strands of physics are linked in the earlyUniverse at around 10 picoseconds, when the electroweak phase transition took place, and the Higgs field"turned on". This process could have been a violent one, generating gravitational waves detectable by spacebasedgravitational wave detectors with sensitivity in the millihertz band. The European Space Agency hasrecently approved just such a mission, Laser Interferometer Space Antenna (LISA), which will launch by2034. LISA has the potential to directly probe of the conditions of the Universe at an age of about 10picoseconds, and at the same time the physics of mass generation. .An early Universe first-order phase transition is characterised as follows. The energy scale is set by thecritical temperature Tc, below which bubbles of the Higgs phase can spontaneously nucleate and grow. Thebubble nucleation rate per unit volume is calculable in terms of the transition rate parameter b, the rate of thechange of the activation barrier. The third parameter a is roughly the potential energy in the Higgs fieldrelative to the thermal energy, which controls the fluid shear stresses, the source for the gravitational waves.The efficiency depends on the final parameter, the speed with which the phase boundary expands vw.There is a strong drive towards the determination of the gravitational wave power spectrum as a function ofthe parameters (Hn,a,b,vw), This project aims to link this programme back to fundamental physics byimproving the computation of the parameters (Hn,a,b,vw) from the masses and coupling constants ofunderlying particle physics models, so that the power spectrum can be computed with 20% accuracy.The wall speed vw is the parameter with the most uncertainty, up to a factor two for low values. This projectwill develop and apply new methods to improve the accuracy of the vw calculation to the required 5% level.Lattice Monte Carlo techniques have good potential, as they treat properly the IR modes of the W and Zfields which are the source of significant uncertainty. The project will explore the use the holographicapproach to strongly-interacting field theories to compute the thermal activation rate from a solution to thedual 5-dimensional gravitational theory.

LIGO/Virgo合作项目对引力波的直接探测表明，研究宇宙的一扇新窗口正在打开，它有可能彻底改变我们对宇宙历史的认识。同样，在大型强子对撞机（LHC）上发现希格斯粒子也引发了对基本粒子质量起源的全面了解。这些最基本的物理学分支在宇宙早期大约10皮秒的时候联系在一起，此时发生了电弱相变，希格斯场“开启”。这个过程可能是剧烈的，产生的引力波可以被灵敏度在毫赫波段的太空引力波探测器探测到。欧洲航天局最近批准了这样一项任务，激光干涉仪空间天线（LISA），将于2034年发射。LISA有可能在大约10皮秒的时间里直接探测宇宙的状态，同时也有可能研究质量生成的物理学。早期宇宙一阶相变的特征如下。能量尺度由临界温度Tc设定，低于此温度，希格斯相的气泡可以自发成核并生长。单位体积的气泡成核速率可以根据转变速率参数b，即活化势垒的变化率来计算。第三个参数a大致是希格斯场中相对于热能的势能，热能控制着流体剪切应力，即引力波的来源。效率取决于最终参数，即相边界扩展的速度vw。在确定引力波功率谱作为参数（Hn,a,b,vw）的函数方面有很强的动力。本项目旨在通过改进基于粒子物理模型的质量和耦合常数的参数（Hn,a,b,vw）的计算，将该项目与基础物理联系起来，从而使功率谱的计算精度达到20%。壁面速度vw是最不确定的参数，对于较低的值可达2倍。该项目将开发和应用新方法，以提高大众计算的准确性，达到所需的5%水平。晶格蒙特卡罗技术具有良好的潜力，因为它可以很好地处理W场和z场的红外模式，而W场和z场是显著不确定性的来源。该项目将探索使用全息方法强相互作用场论来计算双五维引力理论的一个解的热激活率。