Particle Phenomenology, QCD and the Standard Model.

粒子现象学、QCD 和标准模型。

• 批准号: ST/P000274/1
• 负责人: Robert Thorne
• 金额: $ 55.48万
• 依托单位: University College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FP000274%2F1
• 关键词: Particle; Phenomenology; QCD; Standard; Model.

Keith Hamilton's research concerns the development of high precision Monte Carlo simulations of collider Physics processes. These facilitate discovery and interpretation of new physics at the Large Hadron Collider (LHC). While precision simulations may not be needed to claim a discovery, e.g. if new physics appears as a clear `bump' in a smooth distribution, (as did the Higgs boson), in many scenarios, such as supersymmetry, signals are expected to manifest as subtle distortions in the shapes of distributions. An accurate understanding of the Standard Model background, subject to all experimental cuts, is then unavoidable for claiming a discovery, or setting exclusion limits. Precision simulations are also essential to determine what it is that has been found. The recently discovered 125 GeV mass Higgs boson is the prime example of this. In 2012-2013 Hamilton and collaborators in Milan and Oxford developed the world's most accurate simulation of Higgs boson production. This simulation is used by the ATLAS collaboration, appearing in their publications confronted with measurements which test various Higgs boson properties. Hamilton plans to fully exploit the innovations which led to the latter simulation, applying them to produce precision simulations of other important LHC reactions, in particular the W-pair and diphoton production processes, where anomalies have been reported in recent experimental measurements. In tandem with application of these new techniques he has helped develop, Hamilton also plans to continue to press on with further innovations in the theoretical frameworks they are based on, towards greater accuracy.Thorne's work is complementary and in many senses similar. It involves the details of the initial state in particle collisions. At colliders which use hadrons, e.g. the LHC which uses protons, the beam is effectively made up of the hadronic constituents, quarks and gluons, generically known as partons. Hence, in order to make predictions for any reaction, both for Standard Model and new physics, one needs to know the precise partonic composition of the hadrons in terms of both the energy fraction of the hadron and the energy scale of the scattering process (e.g., the mass of a particle produced). Thorne is the lead member of the MMHT (previously MSTW) group that provides one of the standard sets of parton distribution functions (PDFs) used in both the experimental and theoretical analyses at the LHC and previous colliders, and in high energy neutrino and cosmic ray physics. The technique is constantly being improved in terms of the theoretical basis, and more data are appearing which help constrain the PDFs further. Hence, Thorne's work will be based on improving PDF determination, providing updated PDFs for use at colliders (and elsewhere) and helping to investigate the consequences of any changes in both central values and uncertainties. Thorne is also a core member of the PDF4LHC working group (being a member of the steering committee since the inception, and hosting the website) which provides recommendations for use of PDF sets at the LHC.Both Hamilton and Thorne are involved in precision calculations at the LHC and will provide expertise in interpreting any deviations which could be the first sign of Beyond the Standard Model (BSM) Physics.

Keith Hamilton的研究涉及对撞机物理过程的高精度蒙特卡罗模拟的发展。这些有助于在大型强子对撞机（LHC）上发现和解释新的物理现象。虽然可能不需要精确的模拟来宣布一项发现，例如，如果新的物理现象在平滑分布中表现为一个明显的“凸起”（就像希格斯玻色子一样），在许多情况下，比如超对称，信号预计会表现为分布形状的微妙扭曲。对标准模型背景的准确理解，受制于所有的实验删减，对于宣称发现或设置排除限制是不可避免的。精确的模拟对于确定被发现的是什么也至关重要。最近发现的125 GeV质量的希格斯玻色子就是最好的例子。2012-2013年，汉密尔顿与米兰和牛津的合作者开发了世界上最精确的希格斯玻色子生成模拟。这种模拟被ATLAS合作使用，出现在他们的出版物中，面对测试各种希格斯玻色子特性的测量结果。汉密尔顿计划充分利用导致后一种模拟的创新，将它们应用于其他重要的LHC反应的精确模拟，特别是w对和双光子产生过程，在最近的实验测量中已经报告了异常。在他帮助开发的这些新技术的应用中，汉密尔顿还计划继续推动这些技术所基于的理论框架的进一步创新，以达到更高的准确性。索恩的作品是互补的，在很多方面是相似的。它涉及粒子碰撞初始状态的细节。在使用强子的对撞机中，例如使用质子的大型强子对撞机，光束实际上由强子成分，夸克和胶子组成，通常称为部分子。因此，为了对任何反应做出预测，无论是标准模型还是新物理学，人们都需要从强子的能量分数和散射过程的能量尺度（例如，产生的粒子的质量）两方面了解强子的精确部分组成。索恩是MMHT（以前的MSTW）小组的主要成员，该小组提供了一套标准的部分分布函数（pdf），用于大型强子对撞机和以前的对撞机的实验和理论分析，以及高能中微子和宇宙射线物理。该技术在理论基础方面不断得到改进，并且出现了更多有助于进一步限制pdf的数据。因此，索恩的工作将基于改进PDF确定，为对撞机（和其他地方）提供更新的PDF，并帮助调查中心值和不确定性的任何变化的后果。索恩也是PDF4LHC工作组的核心成员（自成立以来一直是指导委员会的成员，并主持该网站），该工作组为在LHC中使用PDF集提供建议。汉密尔顿和索恩都参与了大型强子对撞机的精密计算，并将提供专业知识来解释任何偏差，这些偏差可能是超越标准模型（BSM）物理学的第一个迹象。

项目成果

Snowmass 2021 Whitepaper: Proton Structure at the Precision Frontier

Snowmass 2021 白皮书：精密前沿的质子结构

• DOI: 10.5506/aphyspolb.53.12-a1
• 发表时间: 2022
• 期刊: Acta Physica Polonica B
• 影响因子: 0.5
• 作者: Amoroso, S.;Apyan, A.;Armesto, N.;Ball, R.D.;Bertone, V.;Bissolotti, C.;Blümlein, J.;Boughezal, R.;Bozzi, G.;Britzger, D.
• 通讯作者: Britzger, D.

The Dark Machines Anomaly Score Challenge : Benchmark Data and Model Independent Event Classification for the Large Hadron Collider

黑暗机器异常分数挑战：大型强子对撞机的基准数据和模型独立事件分类

• DOI: 10.18154/rwth-2022-06596
• 发表时间: 2022
• 作者: Aarrestad T

Parton distributions from LHC, HERA, Tevatron and fixed target data: MSHT20 PDFs

• DOI: 10.1140/epjc/s10052-021-09057-0
• 发表时间: 2021-04-01
• 期刊: EUROPEAN PHYSICAL JOURNAL C
• 影响因子: 4.4
• 作者: Bailey, S.;Cridge, T.;Thorne, R. S.
• 通讯作者: Thorne, R. S.