{"title":"顶夸克对产生阈值处伪标量过剩的观察。","authors":"The Cms Collaboration","doi":"10.1088/1361-6633/adf7d3","DOIUrl":null,"url":null,"abstract":"<p><p>A search for resonances in top quark pair (tt-) production in final states with two charged leptons and multiple jets is presented, based on proton-proton collision data collected by the CMS experiment at the CERN LHC ats=13TeV, corresponding to 138 fb<sup>-1</sup>. The analysis explores the invariant mass of thett-system and two angular observables that provide direct access to the correlation of top quark and antiquark spins. A significant excess of events is observed near the kinematictt-threshold compared to the non-resonant production predicted by fixed-order perturbative quantum chromodynamics (pQCD). The observed enhancement is consistent with the production of a color-singlet pseudoscalar (1S0[1]) quasi-bound toponium state, as predicted by non-relativistic quantum chromodynamics. Using a simplified model for1S0[1]toponium, the cross section of the excess above the pQCD prediction is measured to be8.8-1.4+1.2pb.</p>","PeriodicalId":74666,"journal":{"name":"Reports on progress in physics. Physical Society (Great Britain)","volume":" ","pages":""},"PeriodicalIF":20.7000,"publicationDate":"2025-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Observation of a pseudoscalar excess at the top quark pair production threshold.\",\"authors\":\"The Cms Collaboration\",\"doi\":\"10.1088/1361-6633/adf7d3\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p><p>A search for resonances in top quark pair (tt-) production in final states with two charged leptons and multiple jets is presented, based on proton-proton collision data collected by the CMS experiment at the CERN LHC ats=13TeV, corresponding to 138 fb<sup>-1</sup>. The analysis explores the invariant mass of thett-system and two angular observables that provide direct access to the correlation of top quark and antiquark spins. A significant excess of events is observed near the kinematictt-threshold compared to the non-resonant production predicted by fixed-order perturbative quantum chromodynamics (pQCD). The observed enhancement is consistent with the production of a color-singlet pseudoscalar (1S0[1]) quasi-bound toponium state, as predicted by non-relativistic quantum chromodynamics. Using a simplified model for1S0[1]toponium, the cross section of the excess above the pQCD prediction is measured to be8.8-1.4+1.2pb.</p>\",\"PeriodicalId\":74666,\"journal\":{\"name\":\"Reports on progress in physics. Physical Society (Great Britain)\",\"volume\":\" \",\"pages\":\"\"},\"PeriodicalIF\":20.7000,\"publicationDate\":\"2025-08-22\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Reports on progress in physics. Physical Society (Great Britain)\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.1088/1361-6633/adf7d3\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Reports on progress in physics. Physical Society (Great Britain)","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1088/1361-6633/adf7d3","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
摘要
本文利用CERN大型强子对撞机（LHC）在$\sqrt{s}$ = 13 TeV，对应138 fb $^{-1}$下的质子-质子碰撞实验数据，研究了两个带电轻子和多个射流在最终态产生顶夸克对（$\text{t}\bar{\text{t}}$）的共振。分析探讨了\ttbar系统的不变质量和两个角度观测值，这些观测值提供了直接访问顶夸克和反夸克自旋相关性的途径。与固定阶摄动量子色动力学（pQCD）预测的非共振产生相比，在运动学$\text{t}\bar{\text{t}}$阈值附近观察到显著的过量事件。观测到的增强与非相对论量子色动力学预测的色单重态伪标量（$^1$ S $^{[1]}_0$）准束缚toponium态的产生一致。利用$^1$ S $^{[1]}_0$ toponium的简化模型，测得高于pQCD预测的过量截面为8.8 $^{+1.2}_{-1.4}$ pb。
Observation of a pseudoscalar excess at the top quark pair production threshold.
A search for resonances in top quark pair (tt-) production in final states with two charged leptons and multiple jets is presented, based on proton-proton collision data collected by the CMS experiment at the CERN LHC ats=13TeV, corresponding to 138 fb-1. The analysis explores the invariant mass of thett-system and two angular observables that provide direct access to the correlation of top quark and antiquark spins. A significant excess of events is observed near the kinematictt-threshold compared to the non-resonant production predicted by fixed-order perturbative quantum chromodynamics (pQCD). The observed enhancement is consistent with the production of a color-singlet pseudoscalar (1S0[1]) quasi-bound toponium state, as predicted by non-relativistic quantum chromodynamics. Using a simplified model for1S0[1]toponium, the cross section of the excess above the pQCD prediction is measured to be8.8-1.4+1.2pb.
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