The United States contingent of the global CMS collaboration — played a crucial role in this result, contributing to the excellent performance of CMS detector.
全球緊湊型μ介子螺線管(CMS：Compact Muon Solenoid)合作團隊的美國部分(US CMS)，在此研究結果扮演了關鍵性角色，促成了CMS探測器的卓越性能。
US CMS members have been instrumental in the design, construction and upgrades of detector components that capture the particle tracks and help filter potential signals from the background noise: the tracker detector, the muon detectors, the muon trigger system and the computing system. They continue to lead the successful maintenance and operations of these systems.
US CMS的成員們一直在協助設計、建構及升級，捕獲粒子軌跡及幫助過濾來自背景雜訊中，潛在信號的探測器組件：也就是，追踪探測器、μ介子探測器、μ介子觸發系統及計算系統。他們持續引領，這些系統的順利維持及運作。
“US CMS is very proud to acknowledge the significant impact made by its members in deploying innovative analysis techniques, including cutting-edge AI methods, which were critical in establishing the evidence for Higgs boson decays into a muon and antimuon pair,” said Brown University physicist Meenakshi Narain, chair of the US CMS collaboration. “This is a rare process, and finding evidence for it is a vital step toward understanding the Higgs particle and the Standard Model.”
US CMS的合作團隊領導人，美國布朗大學物理學家，Meenakshi Narain宣稱：「US CMS非常自豪地認為，在部署包括確認希格斯玻色子衰變成μ介子及反μ介子對，至關重要之諸多尖端人工智慧方法的創新分析技術上，由其成員們作出的重大影響。這是發現證據的一種罕見過程，因為此過程是邁向瞭解，希格斯粒子與標準模型，不可或缺的一步。」
CMS is an international collaboration with members from 238 institutes across 55 countries. US CMS, hosted by the U.S. Department of Energy’s Fermi National Accelerator Laboratory, makes up about a third of the CMS collaboration.
CMS是一支，具有來55國家、238個研究所成員們，組成的國際合作團隊。由美國能源部費米國家加速器實驗室主持的US CMS，大約構成該CMS合作團隊的三分之一。
“The achievement, reached significantly ahead of what was expected, relies on the excellent performance of our detector, on the large data set provided by LHC and on advanced analysis techniques,” said Roberto Carlin, spokesperson for the CMS experimental collaboration.
該CMS實驗合作團隊發言人，Roberto Carlin宣稱：「這項大大超出預期的成就，仰賴了他們探測器的卓越性能、由大型強子對撞機(LHC：Large Hadron Collider)提供的大數據集，及諸多先進的分析技術。」
The ATLAS and CMS experiments at CERN have announced new results that show that the Higgs boson decays into two muons. The muon is a heavier copy of the electron, one of the elementary particles that constitute the matter content of the universe. While electrons are classified as a first-generation particle, muons belong to the second generation.
於歐洲核子研究組織(CERN： European Organization for Nuclear Research)進行的環狀大型強子對撞機設備(ATLAS：A Toroidal LHC Apparatus)及緊湊型μ介子螺線管實驗已經宣佈過，若干顯示希格斯玻色子衰減成兩個μ介子的新研究結果。電子的一種較重版，μ介子是構成宇宙物質內含物的基本粒子之一。儘管電子被歸類為第一代粒子，不過μ介子屬於第二代粒子。
The physics process of the Higgs boson decaying into muons is a rare phenomenon as only about one Higgs boson in 5,000 decays into muons. These new results have pivotal importance for fundamental physics because they indicate for the first time that the Higgs boson interacts with second-generation elementary particles.
希格斯玻色子衰變成μ介子的物理過程，是一種罕見的現象。因為，在5千個中，僅大約一個衰變成μ介子。此些新研究結果對基礎物理學，具有關鍵的重要性。因為，它們首度顯示希格斯玻色子與第二代基本粒子交互作用。
Physicists at CERN have been studying the Higgs boson since its discovery in 2012 to probe the properties of this very special particle. The Higgs boson, produced from proton collisions at the Large Hadron Collider, disintegrates – referred to as decay – almost instantaneously into other particles. One of the main methods of studying the Higgs boson’s properties is by analyzing how it decays into the various fundamental particles and the rate of disintegration.
打從2012年發現以來，歐洲核研究組織的物理學家們，一直進行研究希格斯玻色子，以探索這種非常特殊粒子的諸多屬性。從質子於大型強子對撞機，碰撞產生的希格斯玻色子，幾乎立即瓦解(被稱為衰變)成其他粒子。研究希格斯玻色子諸屬性的主要方法之一，是藉由分析其如何衰變成各種基本粒子及瓦解速率。
圖1. 由緊湊型μ介子螺線管記錄之希格斯玻色子候選物衰變成兩個μ介子。 (圖援用自原文)
CMS achieved evidence of this decay with 3 sigma, which means that the chance of seeing the Higgs boson decaying into a muon pair from statistical fluctuation is less than one in 700. ATLAS’ two sigma result means the chances are one in 40. The combination of both results would increase the significance well above 3 sigma and provides strong evidence for the Higgs boson decay to two muons.
緊湊型μ介子螺線管獲得了，該具有3Σ(指與平均值相差三個標準差以內的數據)衰變的證據。這意味著，從統計學上的不穩定性，發現希格斯玻色子衰變成μ介子對的機會，不及七百分之一。環狀大型強子對撞機設備2Σ的結果，意味著此些機會是四十分之一。結合這兩種結果，能提升此意義遠超過3Σ。因此，提供了希格斯玻色子衰變成兩個μ介子的有力證據。
“CMS is proud to have achieved this sensitivity to the decay of Higgs bosons to muons and to show first experimental evidence for this process. The Higgs boson seems to interact also with second-generation particles in agreement with the prediction of the Standard Model, a result that will be further refined with the data we expect to collect in the next run,” says Roberto Carlin, spokesperson for the CMS experiment.
CMS實驗發言人，Roberto Carlin宣稱：「CMS以其已經獲得有關，該希格斯玻色子衰變成μ介子的敏感性，及展現此過程的首度實驗證據而自豪。希格斯玻色子似乎也與第二代粒子交互作用，這與標準模型的預測一致。這會是使用，在接下來運作中，他們期待收集之數據，進一步界定的一種結果。」
The Higgs boson is the quantum manifestation of the Higgs field, which gives mass to elementary particles it interacts with, via the Brout-Englert-Higgs mechanism. By measuring the rate at which the Higgs boson decays into different particles, physicists can infer the strength of their interaction with the Higgs field: the higher the rate of decay into a given particle, the stronger its interaction with the field.
希格斯玻色子是希格斯場的量子顯現。希格斯場經由Brout-Englert希格斯機制，賦予與其交互作用之基本粒子的質量。藉由測量希格斯玻色子衰變成不同粒子的速率，物理學家們能推斷它們與希格斯場交互作用的強度：衰變成特定粒子的速度愈高，其與該場的交互作用愈強。
So far, the ATLAS and CMS experiments have observed the Higgs boson decays into different types of bosons such as W and Z, and heavier fermions such as tau leptons. The interaction with the heaviest quarks, the top and bottom, was measured in 2018. Muons are much lighter in comparison, and their interaction with the Higgs field is weaker. Interactions between the Higgs boson and muons had, therefore, not been seen at the LHC.
到目前為止，ATLAS及CMS實驗已經觀察到，希格斯玻色子衰變成，諸如W及Z等不同類型的玻色子，及諸如τ輕子等較重的費米子。與最重之頂夸克及底夸克的交互作用，於2018年被測量。相較之下，μ介子較輕得多，而且它們與希格斯場的交互作用較弱。因此，希格斯玻色子與μ介子之間的交互作用，在大型強子對撞機中，不曾被發現。
圖2. 環狀大型強子對撞機設備的一次候選核粒子生成展現了，希格斯玻色子衰變成兩個μ介子。 (圖援用自原文)
This evidence of Higgs boson decays to second-generation matter particles complements a highly successful Run 2 Higgs physics program. The measurements of the Higgs boson’s properties have reached a new stage in precision and rare decay modes can be addressed. These achievements rely on the large LHC data set, the outstanding efficiency and performance of the ATLAS detector, as well as the use of novel analysis techniques,” says Karl Jakobs, ATLAS spokesperson.
希格斯玻色子衰變為第二代物質粒子的證據補充了，高度順利之第二次運作的希格斯物理計劃。在精確度及諸多稀有衰變模式能被處理上，希格斯玻色子諸屬性的諸多測量已經達到，能解決精確度及諸多罕見衰減模式的新階段。除了使用諸多新的分析技術之外，這些成就也仰賴，大量的大型強子對撞機數據集，及ATLAS探測器的卓越效率及性能。」
What makes these studies even more challenging is that, at the LHC, for every predicted Higgs boson decaying to two muons, there are thousands of muon pairs produced through other processes that mimic the expected experimental signature.
使得此些研究更具挑戰性的是，對每個被預測衰變為兩個μ介子的希格斯玻色子而言，在大型強子對撞機中，具有數千個透過模仿該預期之實驗特徵的其他過程，所產生的μ介子對。
The characteristic signature of the Higgs boson’s decay to muons is a small excess of events that cluster near a muon-pair mass of 125 GeV, which is the mass of the Higgs boson. Isolating the Higgs boson to muon-pair interactions is no easy feat. To do so, both experiments measure the energy, momentum and angles of muon candidates from the Higgs boson’s decay.
希格斯玻色子衰變為μ介子的典型特徵是，群集在質量為125 GeV(希格斯玻色子的質量)之μ介子對附近的少量事件。隔離希格斯玻色子與μ介子對的交互作用並非容易之事。為此，ATLAS及CMS兩種實驗測量了，來自希格斯玻色子衰變之候選μ介子的能量、動量及角度。
In addition, the sensitivity of the analyses was improved through methods such as sophisticated background modelling strategies and other advanced techniques such as machine-learning algorithms. CMS combined four separate analyses, each optimized to categorize physics events with possible signals of a specific Higgs boson production mode. ATLAS divided their events into 20 categories that targeted specific Higgs boson production modes.
此外，經由諸如復雜之背景模型製作策略的方法，及諸如機器學習演算法的其他先進技術，能改善分析的敏感性。CMS結合了四種獨立的分析，每一種經最佳化來分類，具有特定希格斯玻色子生產模式之可能信號的物理事件。ATLAS將它們的事件分成，針對特定希格斯玻色子產生模式的20類。
The results, which are so far consistent with the Standard Model predictions, used the full data set collected from the second run of the LHC. With more data to be recorded from the particle accelerator’s next run and with the High-Luminosity LHC, the ATLAS and CMS collaborations expect to reach the sensitivity (5 sigma) needed to establish the discovery of the Higgs boson decay to two muons and constrain possible theories of physics beyond the Standard Model which would affect this decay mode of the Higgs boson.
此些迄今與標準模型預測一致的研究結果使用了，從大型強子對撞機第二次運作，收集的完整數據集。在獲得來自該粒子加速器，下一次運作及此高光度大型強子對撞機，將被記錄之更多數據的情況下，ATLAS及CMS兩支合作團隊預期獲得，證實發現希格斯玻色子衰變成兩個μ介子所需，及限制諸多會影響此希格斯玻色子衰變模式，超出了標準模型所可能之物理理論的(5Σ)敏感性。
原文網址：https://news.fnal.gov/2020/08/cern-experiments-announce-first-indications-of-a-rare-higgs-boson-process/
翻譯：許東榮
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