Title: Electroweak Precision Measurements at Hadron Colliders（強子對撞實驗上的精確電弱測量）
Speaker: Dr.Siqi Yang (The University of Iowa)
Chair: 梁志均 副研究員（高能所）
Time: 10:00am, Thursday 12th September, 2019
Location: C305 main building
Abstract:
The electroweak precision measurement is among the most important topics in experimental physics. In the past decades, many milestones in particle physics, including the discovery of the W and Z bosons, the top quark and the Higgs boson, benefit from the electroweak precision measurement and corresponding global fitting. From the beginning of this century, electroweak precision measurement has been performed at hadron colliders. After the discovery of the top quark and Higgs boson, it becomes important to help searching the beyond standard model phenomenon (especially for the situation that we did not have clear clue for new physics by direct searching at the LHC). To provide high precision for fundamental parameters in the electroweak theory (the W boson mass and the effective weak mixing angle), multiple topics have to be studied., including one order of magnitude improvement on the lepton reconstruction, better modelling of the PDF and calculation in QCD, and study on the strategy of performing such measurements at high instantaneous luminosity colliders. The reporter will discuss the highlights in the electroweak precision measurement at the Fermilab’s Tevatron, and introduce the current status of measurements at the CERN LHC.
報告摘要：
精確電弱測量一直是實驗物理最重要的領(lǐng)域之一，其相關(guān)研究難度大、周期長。近幾十年的重大發(fā)現(xiàn)，包括W與Z玻色子、top夸克、Higgs玻色子，都極大受益于精確電弱測量與global fitting對其質(zhì)量區(qū)間的精確預(yù)測。從本世紀初開始，精確電弱測量首次迎來高能強子對撞時代。隨著top夸克與Higgs的發(fā)現(xiàn)，精確電弱測量成為尋找新物理最重要的切入點之一（尤其是至今LHC上的直接新物理尋找并未取得顯著線索的情況下）。該領(lǐng)域以關(guān)鍵參數(shù)（W玻色子質(zhì)量與有效弱混合角）測量為物理目標，帶領(lǐng)了一系列相關(guān)課題方向。實驗技術(shù)方面，提出了強子實驗上電子與繆子重建各個方面的最高精度要求（超越現(xiàn)有精度一個數(shù)量級）；理論計算方面，要求顯著降低PDF與QCD誤差；物理測量方面，涉及到系統(tǒng)性的方法設(shè)計。報告人介紹近年來在第一代TeV級強子對撞機Tevatron上的精確電弱測量結(jié)果和主要突破。并討論當前LHC上精確電弱測量的進展情況以及對未來的測量規(guī)劃。
報告人簡介：
楊思奇博士長期從事高能強子對撞實驗上的精確電弱測量研究。主要工作在第一代TeV級強子對撞機Tevatron上的D0實驗，以及第二代TeV級強子對撞機LHC上的ATLAS實驗。具體研究方向包括Z玻色子、W玻色子物理過程的電弱測量，高精度輕子刻度以及質(zhì)子部分子分布函數(shù)PDF研究。其中關(guān)于溫伯格角的測量工作取得了突破，完成了過去十年強子對撞實驗上最精確的一系列測量結(jié)果。
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