Studies of the Higgs boson properties with the ATLAS experiment in LHC.

托马斯将研究新发现的希格斯玻色子的性质，使用的数据收集的ATLAS合作在大型强子对撞机在质量中心= 13 TeV。研究希格斯玻色子的最有效的途径是H到ZZ（*）到4l通道，采用碰撞，其中希格斯玻色子已产生和衰变成Z玻色子，反过来每个衰变成一对带相反电荷的电子或μ子。这个衰变通道在LHC中具有最好的希格斯信号与背景比，并允许对粒子特性进行完整的研究。特别是该项目的目的是：-有助于进一步开发电子重建和识别算法，充分利用ATLAS跟踪器和热量计的能力。这对于H到ZZ（*）到4l通道至关重要，其中所有四个轻子都可以是电子。改进和完善H到ZZ（*）到4l的搜索。这一努力旨在加强信号与背景过程的分离。它与轻子重建和识别的性能改进紧密相关。尽可能精确地确定希格斯玻色子的质量。希格斯玻色子的质量是SM中的一个自由参数，它影响希格斯玻色子的产生和衰变速率。H到ZZ（*）到4l是此测量的最重要通道之一。这是一个很好的测量例子，其中对电子性能的理解起着关键作用。通过使用不同的希格斯产生机制，胶子-胶子融合（ggF），矢量玻色子融合（VBF），与弱玻色子相关的产生（WH/ZH），在H到ZZ（*）到4l通道中测量耦合。这将是确定希格斯玻色子耦合的宝贵投入，也是更好地理解其性质的重要一步。在H至ZZ（*）至4l通道中的VBF和WH/ZH的预期速率预期在SM中相对较小，并且它们需要与占主导地位的ggF产生分开。因此，他们在H到ZZ（*）到4l通道的观测需要进行分析，以测试基本的SM预测。LHC预计在未来3年内在RUN II期间提供约100 fb-1的质量中心能量为13 TeV。这将导致H到ZZ（*）到4l通道的可用统计信息增加约10倍。如果观察到与SM模型预测的显著偏差，则将探索超越SM理论的丰富现象学。如果新的希格斯玻色子的性质与SM的预期一致，那么更高的可用能量和更大的数据量将允许对新发现的希格斯玻色子的性质进行精确测量。托马斯有资格担任ATLAS作者，并从事与ATLAS实验操作相关的服务工作。为此，他将有助于ATLAS电子性能组。其目的是提高重建和识别电子的效率以及测量其能量的精度。这将对希格斯玻色子质量和耦合的精确测量产生直接影响。

Thomas will study the properties of the newly discovered Higgs boson employing date collected by the ATLAS collaboration in LHC at centre of mass = 13 TeV.The most effective route for studying the Higgs boson is the H to ZZ(*) to 4l channel, that employs collisions in which a Higgs boson has been produced and decayed into Z bosons that in turn each decay into an oppositely charged pair of electrons or muons. This decay channel has the best Higgs signal to background ratio in LHC and allows for a complete study of the particle properties. In particular the project aims to:- Contribute to the further development of the electron reconstruction and identification algorithms exploiting the full capabilities of the ATLAS tracker and calorimeter. This is vital for the H to ZZ(*) to 4l channel, where all four leptons can be electrons.- Improve and refine the H to ZZ(*) to 4l search. This effort aims in enhancing the separation of the signal from background processes. It is tightly coupled to the performance improvements of lepton reconstruction and identification.- Determine the mass of the Higgs boson as accurately as possible. The mass of the Higgs boson is a free parameter in the SM which affects its production and decay rates. The H to ZZ(*) to 4l is one of the most important channels for this measurement. This is an excellent example of a measurement for which the understanding of electron performance plays a key role.- Measure the couplings by employing the different Higgs production mechanisms, gluon-gluon fusion (ggF), Vector Boson Fusion (VBF), associated productions with weak bosons (WH/ZH), in the H to ZZ(*) to 4l channel. This would be a valuable input in the determination of the couplings of the Higgs boson and a vital step in understanding better its nature. The expected rates for VBF and WH/ZH in the H to ZZ(*) to 4l channel are expected to be relatively small in the SM and they need to be separated from the dominant ggF production. Thus, their observation in the H to ZZ(*) to 4l channel requires the development of analyses that would test fundamental SM predictions.The LHC is expected to deliver ~ 100 fb-1 during RUN II with a centre of mass energy of 13 TeV over the next 3 years. This will lead to an increase of ~10 times in the available statistics of the H to ZZ(*) to 4l channel. If significant deviations from the SM model predictions are observed, the rich phenomenology of beyond the SM theories will be explored. If the properties of the new Higgs boson are consistent with the SM expectations then the higher available energy and the larger amount of data will allow for precision measurements of the properties of the newly discovered Higgs boson.Thomas has qualify as ATLAS author, and perform service work related to the ATLAS experiment operation. To this effect he will contribute to ATLAS electron performance group. The aim will be to increase the efficiency for reconstructing and identifying electrons and the precision with which their energy is measured. This will have direct implications on the precision measurement of the Higgs boson mass and couplings.