유럽입자물리연구소(CERN)는 14일(현지시간) 지난해 대형강입자충돌기(LHC)에서 검출된 소립자가 '힉스 입자'임이 확실시된다고 밝혔다.
BBC와 AP 등에 따르면 CERN 조 인칸델라 연구팀장은 "어떤 종류의 힉스 입자인지 알아내려면 아직 갈 길이 멀지만 개인적으로 지금 갖고 있는 것이 힉스 입자라는 점은 명확하다"고 말했다.
그는 이탈리아 라투일레에서 열린 연례 물리학회에서 CERN의 분석 결과 지난해 7월 LHC에서 검출된 입자의 '스핀'이 힉스 입자의 특성과 일치한다는 추론에 도달했다고 밝혔다.
CERN 아틀라스 연구팀의 데이브 찰튼 대변인도 "검출된 입자의 스핀 값이 표준모형의 힉스 입자와 같은 것으로 나타나 힉스 입자 단위에서 측정 작업을 진행하고 있다"고 설명했다.
스핀은 입자의 고유한 각(角)운동량으로 힉스 입자는 이 스핀이 제로(0)라야 한다.
이날 AP통신은 CERN 연구팀의 발언을 인용해 힉스 입자 발견이 확실하다고 보도 했지만 다른 외신들은 가능성이 좀 더 커졌다며 추가 규명의 여지를 남겼다.
물리학계는 힉스 입자의 입증 가능성이 커진 것은 맞지만 더 규명해야 한다는 신중한 반응을 보이고 있다.
CERN도 공식 성명에서 힉스 입자 발견이라는 최종 결론에 도달하려면 더 많은 자료를 이용한 추가 분석이 필요하다고 밝혔다.
이에 앞서 CERN 과학자들은 지난 6일 "검출된 입자가 힉스 입자일 가능성은 99.
6%이며 99.9%가 될 때까지 확인할 필요가 있다고 밝힌 바 있다.
힉스 입자는 기본입자들과의 상호작용을 통해 다른 모든 입자에 질량을 부여하는 역할을 하는 존재로 여겨진다.
1964년 영국의 물리학자 피터 힉스가 그 존재를 예언했지만 현재까지 물질을 구 성하는 기본입자 중에서 유일하게 관측되지 않은 가상의 입자다.
입자 '표준모형'에 따르면 모든 물질은 기본입자 12개와 힘을 전달하는 매개입 자 4개, 힉스 입자로 구성된 17개의 작은 입자(소립자)로 이뤄진다.
전자와 물질에 질량을 주는 힉스 입자가 없다면 우주 안에는 어떤 원자도 상호 연결된 상태로 존재할 수 없으며 화학작용이나 생명체도 존재할 수 없는 것으로 여겨진다.
CERN은 이번 분석을 위해 2개 연구팀이 작년보다 2.5배 늘어난 자료를 토대로 연구를 진행했다고 설명했다.
<관련 영문 기사>
Physicists say they have found a Higgs boson
It helps solve one of the most fundamental riddles of the universe: how the Big Bang created something out of nothing 13.7 billion years ago.
In what could go down as one of the great Eureka! moments in physics _ and win somebody the Nobel Prize _ scientists said Thursday that after a half-century quest, they are confident they have found a Higgs boson, the elusive subatomic speck sometimes called the “God particle.”
The existence of the particle was theorized in 1964 by the British physicist Peter Higgs to explain why matter has mass. Scientists believe the particle acts like molasses or snow: When other tiny basic building blocks pass through it, they stick together, slow down and form atoms.
Scientists at CERN, the Geneva-based European Organization for Nuclear Research, announced in July that they had found something that looked like the Higgs boson, but they weren't certain, and they needed to go through the data and rule out the possibility it wasn't something else.
On Thursday, they said they believe they got it right.
“To me it is clear that we are dealing with a Higgs boson, though we still have a long way to go to know what kind of Higgs boson it is,” said Joe Incandela, a physicist who heads one of the two main teams at CERN, each involving about 3,000 scientists.
Whether or not it was a Higgs boson had to be demonstrated by how it interacts with other particles and its quantum properties, CERN said. The data “strongly indicates that it is a Higgs boson,” it said.
The discovery explains what once seemed unexplainable and still is a bit hard for the average person to comprehend. But it means the key theory that scientists use to explain everything works _ for now, at least.
Its discovery could be a strong contender for the Nobel, though it is uncertain whether the prize would go to the 83-year-old Peter Higgs and the others who first proposed the theory, or to the thousands of scientists who found it, or to all of them.
Finding it wasn't easy. It took more than two decades, thousands of scientists and mountains of data from trillions of colliding protons.
And it needed the world's biggest atom smasher _ CERN's Large Hadron Collider, which cost $10 billion to build and run in a 17-mile (27-kilometer) tunnel beneath the Swiss-French border _ to produce the extreme surge of energies simulating those 1 trillionth to 2 trillionths of a second after the Big Bang.
The Higgs boson is so elusive that only about one collision per trillion will produce one of them in the collider.
CERN said it is open question whether this is the Higgs boson that was expected in the original formulation, or the lightest of several Higgses predicted in some theories that go beyond that model.
“We found a new particle and we want to know how it behaves, and maybe it behaves the way it was predicted in 1964, maybe it's a little bit different,” said physicist Sean Carroll of the California Institute of Technology, who isn't involved in the research.
Finding a Higgs more or less as expected is actually a bit deflating, Carroll said, because physicists had also hoped that an unexpected type of Higgs might open windows into yet more mysteries of the universe.
“Scientists always want to be wrong in their theories. They always want to be surprised,” he said. “It's a bittersweet victory when your theory turns out to be right, because it means, on the one hand, you're right, that's nice, but on the other hand, you haven't learned anything new that's surprising.”
Some of the remaining mysteries including why gravity is so weak and what is the dark matter that is believed to make up a large part of the total mass in the universe, said Patty McBride, who heads a center at the Fermilab in Chicago. (AP)
