论文标题
搜索与LHC处的Atlas检测器在压缩质谱中的超对称颗粒的产生
Search for electroweak production of supersymmetric particles in compressed mass spectra with the ATLAS detector at the LHC
论文作者
论文摘要
提出了两个分析，以搜索通过电子相互作用的超对称颗粒产生的产生：chargino搜索，针对将Charginos衰减到W Bosons和Nutmentrinos的成对产生，以及位移的轨道搜索，寻找来自Higgsinos腐烂的带电轨迹。这些搜索目标是压缩相位空间，其中近来和最轻的超对称粒子之间的质量差异相对较小。搜索使用在LHC处的Atlas检测器以13 TEV的质量质量能量收集的质子 - 质子碰撞数据。在Chargino搜索中，charginos和中性群之间的目标质量差异接近W玻色子的质量。在这样的相空间中，Chargino对的产生在运动学上与WW背景相似，这使得Chargino信号在实验上具有挑战性，可以与WW背景区分开。采用机器学习技术来将超对称信号与背景分开。结果排除了Chargino的质量大约140 GEV的质量分裂降至约100 GEV，在特别有趣的区域中取代了先前的结果，在这些区域中，Chargino对生产可能隐藏在相似的WW背景后面。在流离失所的轨道搜索中，产生的丁香和最轻的中性质量之间的质量差异降至0.3 GEV。实验签名具有低势头的轨道，其起源从碰撞点流离失所。结果表明，如果数据中未观察到过多，则分析具有排除高达175 GEV的不同假设的敏感性。对于较低的质量，较大的信号横截面可以使不同的质量分裂场景获得更高的意义。所有这些信号假设尚未通过对LHC数据的任何现有分析来探讨。
Two analyses searching for the production of supersymmetric particles through the electroweak interaction are presented: the chargino search, targeting the pair production of charginos decaying into W bosons and neutralinos, and the displaced track search, looking for charged tracks arising from the decays of higgsinos into pions. These searches target compressed phase spaces, where the mass difference between the next-to-lightest and lightest supersymmetric particle is relatively small. The searches use proton-proton collision data collected at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. In the chargino search, the targeted mass difference between charginos and neutralinos is close to the mass of the W boson. In such phase space, the chargino pair production is kinematically similar to the WW background, making the chargino signal experimentally challenging to be discriminated from the WW background. Machine learning techniques are adopted to separate the supersymmetric signal from the backgrounds. The results exclude chargino masses up to about 140 GeV for mass splittings down to about 100 GeV, superseding the previous results in particularly interesting regions where the chargino pair production could have hidden behind the looking-alike WW background. In the displaced track search, the mass difference between the produced sparticles and the lightest neutralinos goes down to 0.3 GeV. The experimental signature has a low momentum charged track with an origin displaced from the collision point. The results show that the analysis has the sensitivity to exclude different hypotheses for higgsino masses up to 175 GeV if no excess is observed in data. For lower masses, the larger signal cross-section allows to achieve higher significance for different mass splitting scenarios. All these signal hypotheses have not been probed by any existing analysis of LHC data.
