Discovery of the Xi-cc-plus Baryon at CERN

• 19 Mar 2026

Source: TH 

The Large Hadron Collider beauty (LHCb) experiment at CERN’s Large Hadron Collider (LHC) has announced the discovery of a new particle, the Xi-cc-plus, a heavy baryon that will help physicists better understand how the strong force binds protons, neutrons and other composite particles together.  

• About Xi-cc-plus Particle: The Xi-cc-plus consists of two charm quarks and one down quark, making it a heavy sibling of the proton (which has two up quarks and one down quark). 
  • It was produced by smashing high-energy protons in the Large Hadron Collider (LHC). Like most hadrons, it is unstable and decays rapidly. 
  • This is the first new particle found since the 2023 LHCb detector upgrades, bringing the total number of hadrons discovered by LHC experiments to 80. 
• Physical Properties: Due to the presence of two heavy charm quarks, the particle is approximately 4 times heavier than a proton and has a significantly shorter lifetime than its counterparts. 
• Rare Find: This marks only the 2nd time a baryon containing two heavy quarks has ever been observed. The first, a similar particle with two charm quarks and an up quark, was discovered by LHCb in 2017. 
• Scientific Significance: The discovery helps theorists test models of Quantum Chromodynamics (QCD), the theory describing the strong force that binds quarks into hadrons (mesons and baryons). 
  • It opens doors for studying exotic hadrons like tetraquarks and pentaquarks, setting the stage for future research at the High-Luminosity LHC. 
  • QCD is the theoretical framework in particle physics that describes the strong nuclear force, one of the four fundamental forces of nature. It explains how quarks and gluons interact to form composite particles like protons, neutrons, and mesons.

Large Hadron Collider (LHC) 

• LHC is the world’s largest and most powerful particle accelerator located at CERN near Geneva. It boosts particles, such as protons, to nearly the speed of light in two high-energy beams traveling in opposite directions.  
  • These beams are then made to collide at four specific points around the ring, where massive detectors (like ATLAS, CMS, and LHCb) record the resulting "subatomic debris." 

Key Terms 

• Baryon: A baryon is a type of composite subatomic particle made up of three quarks, held together by the strong nuclear force. Along with mesons (which consist of one quark and one antiquark), baryons belong to the broader family of particles known as hadrons. 
• Quark: Quarks are elementary particles and fundamental building blocks of matter. They carry a fractional electric charge (either +2/3 or -1/3). 
• Antiquark: Every quark has a corresponding antiparticle known as an antiquark. An antiquark has the same mass as its quark counterpart but possesses opposite physical charges. If a charm quark has a +2/3 charge, the charm antiquark has a -2/3 charge. If a quark is "blue," its antiquark is "anti-blue." 

Read More: Large Hadron Collider