雅思阅读 138: The Higgs Boson Under the Microscope（希格斯玻色子被"放大观察"）

改编自 CERN / CMS Collaboration（2026年4月）。雅思阅读 Section 3 难度，约 1050 词。 素材来源：https://cms.cern/news/discovery-deep-dive-higgs-boson-under-microscope

Reading Passage

A. In July 2012, two teams working at CERN's Large Hadron Collider announced that they had found a new particle with a mass around 125 gigaelectronvolts, behaving as theorists had predicted the long-sought Higgs boson should. The discovery closed a chapter that had opened nearly half a century earlier, and it was celebrated around the world. Yet finding the particle was never the end of the story. The Higgs boson matters because of what it does: it is the visible hint of a field that pervades the universe and gives other elementary particles their mass. Whether the particle behaves exactly as the Standard Model of particle physics demands, or shows subtle deviations that would point to newer physics, depends not on a single discovery run but on years of increasingly precise measurement. A decade on, that second, slower work is now the main business at CERN. The 2012 discovery was, in this sense, a door opening onto a much longer corridor: the boson itself had to be characterised, its couplings mapped, its decays catalogued, before anyone could say whether the Standard Model stood or wavered.

B. Physicists often speak of studying a particle by watching how it decays. The Higgs boson is unstable, breaking apart almost immediately after it is created, and the debris it leaves behind carries the signature of its properties. One decay mode is especially prized: the Higgs decays into two Z bosons, which themselves decay into four charged particles — two electrons and two muons, or four of one kind. Because four charged particles can be reconstructed with such precision in the detector, this "golden channel" gives the cleanest image of the parent particle. Its drawback is rarity: only roughly one Higgs decay in ten thousand follows this route. Yet rarity is a price worth paying for clarity, and the volume of data now collected at the collider is large enough that even rare events accumulate. Electrons and muons behave quite differently inside the detector: electrons deposit their energy in the electromagnetic calorimeter and leave tracks in the inner tracker, while muons travel all the way through to dedicated muon chambers at the outermost layers. Reconstructing all four final-state particles with high precision lets physicists infer the mass and momentum of the decaying parent as if from its own fingerprint.

C. The most recent analysis from the CMS experiment used data recorded over three years, from 2022 to 2024, when the collider ran at an unprecedented collision energy of 13.6 teraelectronvolts. The dataset, measured in inverse femtobarns, represents nearly twenty times the information on hand at the moment of the discovery. With that volume came both a sharper signal and a far more demanding test. Rather than merely confirming that a bump exists in the four-lepton spectrum, the team could now measure how the Higgs is produced — how often it appears moving fast, how often it is accompanied by sprays of other particles, and at what angles its decay products emerge. These so-called differential measurements let physicists compare the data not just with the Standard Model in general, but with detailed theoretical calculations of how the boson should be made. The technique is demanding because the collision environment in Run 3 was far busier than in earlier runs, with many overlapping proton-proton interactions crowding each recorded event. Reconstruction algorithms had to be rebuilt to disentangle the Higgs signal from this background without washing it out.

D. The result, for now, is reassuring and quietly disappointing in equal measure. The measurements agree with Standard Model predictions, and no statistically significant deviation has yet surfaced. That is reassuring because the Standard Model has survived every test thrown at it for half a century, and a miscalibration in the experiment itself could have produced a spurious discrepancy. It is disappointing in the sense that physicists hope, almost desperately, for the smallest crack in the theory — a hint of dark matter, extra dimensions, or some new force — because the Standard Model is known to be incomplete. The way forward, as in precision work of every kind, is simply to accumulate more data and refine the analysis. Calibration of the tracking system, sharper measurements of electron and muon energies, and new reconstruction techniques for the busy collision environment all reduce the uncertainty that currently hides any tiny deviation. In this kind of science, a missing effect is itself a result: it tells theorists where their models are allowed to be wrong, and it narrows the territory that new physics would have to occupy.

E. Other teams at CERN are pushing into even rarer corners. The ATLAS experiment recently reported independent evidence that the Higgs can decay into a pair of muons, a process that would confirm how the boson couples to particles in the second generation of matter. CMS has searched for the decay of the Higgs into charm quarks, using machine-learning tools to separate signal from background. Both collaborations have been hunting the simultaneous production of two Higgs bosons, which would reveal how the particle interacts with itself and therefore how stable the universe is. In 2025 the four large CERN experiments shared a major science prize for precisely this programme of detailed measurement. The era of simply asking whether the Higgs exists is over. The new question is whether it is exactly what we think it is — and the microscope is still being turned up. The collider is expected to run for years more, collecting datasets still larger than the one just analysed, and the planned high-luminosity upgrade will multiply the number of Higgs bosons produced by a factor of ten. Each increase sharpens the measurement a little further, and it is in that slow, patient sharpening that any crack in the Standard Model is most likely to show.

Questions 1-4

Choose the correct heading for paragraphs B, C, D and E from the list of headings below.

List of Headings i. How physicists "read" a Higgs decay ii. Why the Higgs was predicted in the 1960s iii. A decade of new data and finer measurements iv. Agreement with theory — and the hope of finding a crack v. The cost of building the Large Hadron Collider vi. Pushing into ever rarer decay modes vii. Why electrons are heavier than muons

1. Paragraph B: ____
2. Paragraph C: ____
3. Paragraph D: ____
4. Paragraph E: ____

Questions 5-8

Choose the correct letter, A, B, C or D.

5. Why is the four-lepton decay called the "golden channel"? A. It produces gold particles. B. It yields a very clear and precisely reconstructible signature. C. It occurs in ten percent of all decays. D. It was discovered last.

6. How much more data does the latest CMS analysis use compared with the discovery period? A. Roughly twice as much. B. About twenty times as much. C. No more than before. D. A thousand times as much.

7. What is the writer's attitude toward the absence of deviations from the Standard Model? A. Purely relieved. B. Purely disappointed. C. Both reassuring, because the model holds, and disappointing, because physicists hope for cracks. D. Indifferent.

8. Why are physicists studying pairs of Higgs bosons? A. To measure the mass of muons. B. To learn how the Higgs interacts with itself and test the universe's stability. C. To prove the Standard Model wrong. D. To reduce the cost of the experiment.

Questions 9-13

Do the following statements agree with the claims of the writer?

Write:

• TRUE if the statement agrees with the information
• FALSE if the statement contradicts the information
• NOT GIVEN if there is no information on this

9. The Higgs boson was discovered at CERN in July 2012.
10. The four-lepton decay occurs in roughly one in ten thousand Higgs decays.
11. The latest CMS data were collected at a collision energy of 13.6 teraelectronvolts.
12. The new analysis has already found statistically significant evidence for new physics beyond the Standard Model.
13. The Higgs boson's mass is around 125 gigaelectronvolts.

Questions 14-15

Complete the summary below using NO MORE THAN TWO WORDS from the passage.

In the "golden channel", the Higgs decays into two (14) __________ bosons, which in turn produce four charged leptons that can be reconstructed with high (15) __________.

答案与解析

← 上一篇 | 返回雅思焦点 | 下一篇 →