Study of new boson W_1~± in the Minimal Higgsless Model at the LHC

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...     

Application of the parametric for mulae for electromagnetic showers in unconverted γ/π~0 discrimination

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.     

W-S中含Fermi圈的光子链传播子及其e-e+→μ-μ+截面

研究电弱统一标准模型(W-S)里的电磁相互作用,传递相互作用的是γ,光子传播子,并对光子传播子里的"树图"以及出现轻子与夸克混合圈中的"链圈图"及其"链图"作了考察与分析,获得光子重整化链图传播予函数"精确"解析计算结果.利用这一结果,又对高能物理中备受关注的一类轻子反应:e-e →μ-μ 作了有关研究,计算出在光子链图传播下的反应截面,并获得"精确"理论计算结果,同时还与实验结果作了对比分析,发现本文理论计算结果与实验吻合较好,获得了有关"辐射修正"的许多重要分析结果.     

遗迹引力波对宇宙微波背景辐射极化的影响

根据宇宙大爆炸理论的预言，宇宙经历了由暴涨阶段到辐射阶段到物质阶段再到如今的加速膨胀阶段.在辐射阶段所残留的退耦的自由光子便形成了现在人们所观测到的宇宙微波背景辐射.如果没有扰动，微波背景辐射将是各向同性的，但是在宇宙形成的初期存在各种各样的扰动，因此宇宙微波背景辐射呈现各向异性.针对由遗迹引力波对微波背景辐射极化所产生的各向异性的影响，重点讨论电场型极化和磁场型极化. 关键词： 遗迹引力波 微波背景辐射 极化各向异性     

W-S中含Fermi圈的光子链传播子及其 截面

研究电弱统一标准模型(W-S)里的电磁相互作用，传递相互作用的是 光子传播子，并对光子传播子里的“树图”以及出现轻子与夸克混合圈中的“链圈图”及其“链图”作了考察与分析，获得光子重整化链图传播子函数 “精确”解析计算结果. 利用这一结果，又对高能物理中备受关注的一类轻子反应： 作了有关研究，计算出在光子链图传播下的反应截面，并获得“精确”理论计算结果，同时还与实验结果作了对比分析，发现本文理论计算结果与实验吻合较好，获得了有关“辐射修正”的许多重要分析结果。     

精确计算n-n重正化链图传播下n+n→２π0反应截面

采用中子n-反中子n与中性介子π⁰强相互作用的Lorentz不变耦合模型，对n-n重正化链图传播子作了有关物理分析及其严格解析计算，获得精确理论计算结果. 进而将此结果用于n+n→2π⁰反应的物理过程分析及其截面的计算研究中，并精确计算出n-n重正化链图传播下n+n→2π⁰反应微分截面. 还将此计算结果与n-n树图和重正化单圈链图传播下n+n→2π⁰反应微分截面作了对比分析，获得了有关辐射修正的重要信息. 此结果对于深 关键词： Lorentz不变耦合模型 重正化链图传播子 微分截面 辐射修正     

Study of new boson W±1 in the Minimal Higgsless Model at the LHC

The Minimal Higgsless Model predicts the existence of new vector gauge boson W1^±, By the process PP →W1^±qq →W^±Z^0qq, Z^0→ 1^＋1^-, W^±→ qq （1=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^±Z^0qq at tree level is developed with the Minimal Higgsless Model and then interfaced with PYTHIA for the patton showers and hadronization. The backgrounds are produced with MadGraph and PYTHIA.     

精确计算电子重整化链图传播下的Compton散射微分截面

采用电子与光子电磁相互作用最小耦合模型,对电子重整化链图传播下Compton散射微分截面作了严格解析计算,获得精确理论结果;并将该计算结果与电子树图和重整化单圈图传播下Compton散射微分截面作对比分析,获得了有关辐射修正的重要信息.此研究结果对精确描述Compton散射现象以及对电磁相互作用所呈现的复杂内部过程的深入探讨,都将从一个重要研究侧面给出理论计算研究方面某些可供借鉴与参考之处.     

A method for the separation and reconstructions of charged hadron and neutral hadron from their overlapped showers in an electromagnetic calorimeter

The separation and reconstructions of charged hadron and neutral hadron from their overlapped showers in an electromagnetic calorimeter is very important for the reconstructions of some particles with hadronic decays, for example the tau reconstruction in the searches for the Standard Model and supersymmetric Higgs bosons at the LHC. In this paper, a method combining the shower cluster in an electromagnetic calorimeter and the parametric formula for hadron showers, was developed to separate the overlapped showers between charged hadron and neutral hadron. Taking the hadronic decay containing one charged pion and one neutral pion in the final status of tau for example, satisfied results of the separation of the overlapped showers, the reconstructions of the energy and positions of the hadrons were obtained. An improved result for the tau reconstruction with this decay model can be also achieved after the application of the proposed method.     

A study of hadronic shower development in the ECAL of the alpha magnetic spectrometer Ⅱ

In this paper, we studied the development of hadronic shower in an electromagnetic calorimeter of Alpha Magnetic Spectrometer Ⅱ. Two parametrized empirical formulae were proposed to describe the hadronic shower shape in calorimeter. Using 100 GeV proton beam incident on the center of the ECAL, detailed plots of lateral and longitudinal hadronic shower behavior were given and we found the formulae can describe the development of the hadronic shower with the test beam data. The possible application of the parametrized formulae including e^±-π^± discrimination and tau jet reconstruction was discussed.