LHCb Collaboration discovers new proton-like particle

The LHCb experiment at CERN’s Large Hadron Collider (LHC) has discovered a new particle consisting of two charm quarks and one down quark, a similar structure to the familiar proton, but with two heavy charm quarks replacing the two up quarks of the proton, thus quadrupling its mass. The discovery, presented at the ongoing Moriond conference, will help physicists better understand how the strong force binds protons, neutrons and other composite particles together. Quarks are fundamental building blocks of matter and come in six flavours: up, down, charm, strange, top and bottom. They usually combine in groups of twos and threes to form mesons and baryons, respectively. Unlike the stable proton, however, most of these mesons and baryons, which are collectively known as hadrons, are unstable and short-lived, making them a challenge to observe. Producing them requires smashing together high-energy particles in a machine such as the Large Hadron Collider (LHC). These unstable hadrons will quickly decay, but the more stable particles that are produced as a result of this decay can be detected and the properties of the original particle can therefore be deduced. Researchers have used this approach many times to find new hadrons, and the new particle just announced by the LHCb Collaboration brings the total number of hadrons discovered by LHC experiments up to 80. “This is the first new particle identified after the upgrades to the LHCb detector that were completed in 2023, and only the second time a baryon with two heavy quarks has been observed, the first having being observed by LHCb almost 10 years ago,” says LHCb Spokesperson Vincenzo Vagnoni. “The result will help theorists test models of quantum chromodynamics, the theory of the strong force that binds quarks into not only conventional baryons and mesons but also more exotic hadrons such as tetraquarks and pentaquarks.” In 2017, LHCb reported the discovery of a very similar particle, which consists of two charm quarks and one up quark. This up quark is the only difference between this particle and the new one, which has a down quark in its place. Despite the similarity, the new particle has a predicted lifetime that is up to six times shorter than its counterpart, due to complex quantum effects. This makes it even more challenging to observe. By analysing data from proton–proton collisions recorded by the LHCb detector during the third run of the LHC, the LHCb Collaboration observed the new baryon with a statistical significance of 7 sigma, well above the threshold of 5 sigma required to claim a discovery. “This major result is a fantastic example of how LHCb’s unique capabilities play a vital role in the success of the LHC,” says Mark Thomson, CERN Director-General. “It highlights how experimental upgrades at CERN directly lead to new discoveries, setting the stage for the transformative science we expect from the High-Luminosity LHC. These achievements are only possible thanks to the exceptional performance of CERN’s accelerator complex and the teams who make it all work and to the commitment of the scientists on the LHCb experiment.” Further information: LHCb presentation at Moriond is available here. LHCb news article.

home.cern · CERN

Ask HN: How do you deal with people who trust LLMs? | Hacker News

news.ycombinator.com

미국과 협상할 인물 모두 죽이는 이스라엘···라리자니 암살에 “전쟁 더 길어질 것”

전시 이란의 실권자로 국정운영을 총괄했던 알리 라리자니 최고국가안보회의(SNSC) 사무총장이 이스라엘에 표적 암살당하면서 전쟁이 장기화할 수 있다는 전망이 나온다. 강경 군부와 온건파 간 중재 역할을 해온 ‘실용적 보수주의자’ 라리자니의 죽음으로 군부의 장악력이 커지면서 종전을 위한 외교적 해법을 찾기 어려워질 수 있다는 것이다. SNSC는 18일(현...

www.khan.co.kr · 경향신문

29년간 한국서 5남매 키운 엄마, ‘가족해체’ 폭탄 품고 하루하루 째깍째깍

찔끔찔끔 내놓는 정부의 한시적 ‘체류자격’ 연장 대책… 그나마 이주노동자 가족 대다수에겐 ‘그림의 떡’

h21.hani.co.kr · 한겨레21