"Search for New Particles in e^+e^- Collisions by the TOPAZ Detector"

“通过 TOPAZ 探测器搜索 e^ e^- 碰撞中的新粒子”

• 批准号: 62540201
• 负责人: SUZUKI Shiro
• 金额: $ 1.34万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1987
• 资助国家: 日本
• 起止时间: 1987 至 1988
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-62540201/
• 关键词: e^+e^- collision; TRISTAN; TOPAZ detector; top quark; heavy lepton; electro-weak theory; the standard model; 超対称性粒子探索; e^+e^-衡突; QED; トップクォーク探索; 重レプトン探索

The TOPAZ detector has been operated since May 1987,and accumulated data at the center of mass energies from 52 to 60.8 GeV.For the off-line data analysis,we established a facility of processing the raw data at the high energy physics laboratory in Nagoya university,fully utilizing its dedicated mainframe computer system.KEKshared in 'pass-one' processing,while Nagoya shared in 'pass-two' processing in which the final calibration constants were used.As the result,we could get the final version of full DSTs for the physics analysis within a month after the data taking period.In looking for new particles and new phenomena,we carried out a search for top quark in the multi-hadron events,a search for heavy lepton,a measurement of forward-dackward asymmetry in the lepton pair production,and a search for supersymmetric (SUSY) particles.Top quark search was done by mesuring R-ratio and analysing event shape,and we found no positive evidence of top quark production upto <square root>s=55 GeV.However,the possibility of the production of charge-1/3 quark of the 4-th generation was not ruled out with the resent statistics. The result of a heavy lepton search was negative,and mass lower limit was set at 25.5 GeV/c^2. Forward-backward asymmetries of and pair production were consistent with the prediction of W-S standard model,and did not require the existance of the 2nd Z boson (Z').A search for pair produced SUSY particles was done.The candidate events were consistent with possible background processes like QED,and the lower mass limit for scaler ,scaler and scaler quark were renewed as 24.5 GeV/c^2,21.7 GeV/c^2 and 26.3 GeV/c^2,respectively.Along with these analyses,importance of making the TOPAZ detector be hermetic (to be sensitive to the single photon events) was realized if we were to be competitive with LEP-SLC in the field of the new particle search,and the upgrading project made progress.

黄玉探测器自1987年5月投入运行以来，积累了52 ~ 60.8GeV的质心能量数据。为了进行离线数据分析，我们在名古屋大学高能物理实验室建立了一套原始数据处理装置，充分利用了该实验室专用的计算机主机系统。而名古屋则采用了“第二遍”的处理方式，使用了最终的定标常数。因此，在数据采集期结束后的一个月内，我们就可以得到完整的DST的最终版本，用于物理分析。在寻找新粒子和新现象时，我们在多强子事例中寻找顶夸克，寻找重轻子，测量轻子对产生的前向-后向不对称性，寻找超对称粒子，通过测量R比和分析事例形状来寻找顶夸克，在s=55 GeV之前没有发现顶夸克产生的确切证据<square root>，但目前的统计资料并不排除产生第四代1/3电荷夸克的可能性.重轻子搜索的结果是否定的，质量下限设定为25.5 GeV/c^2。对产生的SUSY粒子进行了搜索，发现候选事件与QED等可能的背景过程一致，标度、标度和标度夸克的质量下限更新为24.5 GeV/c^2，并对它们的产生进行了讨论。通过这些分析，认识到了TOPAZ探测器的密封性（对单光子事件敏感）对于在新粒子研究领域与LEP-SLC竞争的重要性，并使TOPAZ探测器的升级工程取得了进展。

项目成果

I.Adachi 他: Physics Letters. 208B. 319-323 (1988)

I.Adachi 等人：《物理学快报》208B 319-323 (1988)。

I.Adachi 他: Physics Letters. 218B. 105-111 (1989)

I.Adachi 等人：《物理学快报》218B（1989）。

I.Adachi et al.: "Charge Asymmetry Mearsurement in e^+e^- and Reactions at <square root>=52 and 55 GeV" Physics Letters. 208B. 319-323 (1988)

I.Adachi 等人：“e^ e^- 中的电荷不对称测量和 <平方根>=52 和 55 GeV 处的反应”物理快报。

I. Adachi 他: Physical Review.

I. Adachi 等人：《物理评论》。

I.Adachi 他: Physical Review D. 37. 1339-1342 (1988)

I.Adachi 等人：《物理评论》D. 37. 1339-1342 (1988)