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1.
The CMS and ATLAS experiments at the LHC have announced the discovery of a Higgs boson with mass at approximately 125 GeV/c2 in the search for the Standard Model Higgs boson via, notably, the γγ and ZZ to four leptons final states. Considering the recent results of the Higgs boson searches from the LHC, we study the lightest scalar Higgs boson h1 in the Next-to-Minimal Supersymmetric Standard Model by restricting the next-to-lightest scalar Higgs boson h2 to be the observed to the 125 GeV/c2 state. We perform a scan over the relevant NMSSM parameter space that is favoured by low fine-tuning considerations. Moreover, we also take the experimental constraints from direct searches, B-physics observables, relic density, and anomalous magnetic moment of the muon measurements, as well as the theoretical considerations, into account in our specific scan. We find that the signal rate in the two-photon final state for the NMSSM Higgs boson h1 with the mass range from about 80 GeV/c2 to about 122 GeV/c2 can be enhanced by a factor of up to 3.5 when the Higgs boson h2 is required to be compatible with the excess from latest LHC results. This motivates the extension of the search at the LHC for the Higgs boson h1 in the diphoton final state down to masses of 80 GeV/c2, particularly with the upcoming proton-proton collision data to be taken at center-of-mass energies of 13-14 TeV.  相似文献   
2.
The Neighbor Cell Deposited Energy Ratio (NCDER) is a new method that is proposed to reconstruct incidence position in a single layer for a 3-dimensional imaging electromagnetic calorimeter (ECAL). This method was applied to reconstruct the ECAL test beam data for the Alpha Magnetic Spectrometer-02 (AMS-02). The results show that this method can achieve an angular resolution of 7.36±0.08°/√E+0.28±0.02° in the determination of the photon's direction, which is much more precise than that obtained with the commonly-adopted Center of Gravity (COG) method (8.4±0.1°/E+0.8±0.3°). Furthermore, since it uses only the properties of electromagnetic showers, this new method could also be used for other type of fine grain sampling calorimeters.  相似文献   
3.
 大型强子对撞机(Large Hadron Collider,简称LHC)2010 年3 月开始运行,对撞能量为7TeV,这是设计能量14 TeV 的一半。瞬时亮度从1027cm-2s-1迅速上升,2010 年底达到1032cm-2s-1,2011 年底达到1033cm-2s-1,积分亮度有5/fb, 超过原来的预期。LHC 进入出成果阶段。  相似文献   
4.
LHC(large hadron collider)是目前世界上能量最高的强子对撞机.CMS(compact muon solenoid,中文译名是紧凑型缪子螺线管探测器)是LHC上的主要实验计划之一,其目标就是要寻找Higgs粒子或者超出标准模型的其他新粒子,探清自然界的电弱破缺机制,以及寻找暗物质.CMS实验位于高能量和高亮度的最前沿,是21世纪初人类认识微观世界最重要的物理实验之一.中国参加了这项国际合作,制作了部分μ子探测器、磁铁支架、电子学和地板等,目前转入物理研究工作,争取在物理研究中作出有显示度的贡献.文章简要介绍了CMS探测器以及CMS实验的目标和意义.  相似文献   
5.
The Minimal Higgsless Model predicts the existence of new vector gauge boson W1± . By the process PP → W1± qq → W±Z0qq, Z0 → l+l-, W±→ qq (l=e,μ; q is hadronized to be jets), we study the sensitivity of searching for this possible vector gauge boson in the level of generator events of signal and backgrounds, then give integrated luminosity required to discover 5σ signal as a function of W1± mass. The generator for the signal PP→W1± qq→W±Z0qq at tree level is developed with the Minimal Higgsless Model and th...  相似文献   
6.
田丁  卞建国  陈国明  陈和生 《中国物理 C》2001,25(12):1213-1218
运用模拟软件GEANT3对铅加闪烁光纤类型的BESⅢ桶部电磁量能器(BSC)进行了模拟.研究表明,BSC中簇射的时间信息的读出有助于改善z向分辨、π0的质量分辨和排除假光子.模拟计算还给出了BSC能量分辨率(6%/E),方向角分辨与读出粒度的关系,π0质量分辨率σm/m与光输出、光纤衰减长度及读出粒度的关系,其中m为两个光子重建为π0的不变质量.  相似文献   
7.
研究利用最小电离的质子和已知能量的电子来刻度铅–闪烁光纤夹层电磁量能器.对最小电离粒子输出响应进行光纤衰减修正后,利用最小电离质子的输出响应对量能器测量单元进行标定,然后对不同入射能量的电子事例进行能量重建,重建能量与入射能量有很好的线性关系.本文还对最小电离的质子与μ子对量能器测量单元的输出响应进行了比较,发现二者在误差范围内是一致的.  相似文献   
8.
低能离子束与表面相互作用主要呈现溅射、注入等现象。本文研究了在1.35keVN2+离子注入形成氮化硅的特性,并研究了注入和溅射的并存过程。在高剂量、低能(<10keV)注入的情况下,提出了有效剂量的概念,并建立了刻蚀速率、射程与有效注入剂量的关系。还用俄歇电子能谱(AES)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)、背散射分析(RBS)测定了薄膜的有关特性。 关键词:  相似文献   
9.
首次对τ→π2π0v衰变的结构函数进行了模型无关的实验测量,并与KS模型、IMR模型和Feindt模型进行了比较,在误差范围内,三种理论模型与实验结果一致.与OPAL组测量的τ→3π±v道的结构函数相比,在0.5<Q2<2.75GeV2范围内未发现明显差异.  相似文献   
10.
In the LHC experiment, the neutral pions produced during jet fragmentation are the background sources for all physics channels with high-energy photons in their final state. In this paper, the application of the three-dimensional parametric formula for electromagnetic (EM) showers, which we developed in the Alpha Magnetic Spectrometer II experiment, is presented to distinguish the unconverted photons from the neutral pions. With the constructed electromagnetic calorimeter (ECAL) in a GEANT4 simulation, the parametric formulae were validated and the unconverted γπ0 discrimination was performed with the Toolkit for Multivariate Data Analysis (TMVA) package in ROOT for different transverse energies ranging from 15 GeV to 75 GeV, which is the most sensitive region for light Higgs (with mass ~120 GeV) searches with the channel H→γγ. With this discrimination method and the selected transverse energy region, we can reject π0 with the efficiency from ~40% (65--75 GeV) to ~90% (15--25 GeV) when keeping 90% γ efficiency.  相似文献   
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