Discovery of the ? cc + Particle at the LHC: A New Chapter in Particle Physics

Researchers at CERN's Large Hadron Collider (LHC) have announced the discovery of a new particle, the ? cc + (Xi-cc-plus), which is a heavier cousin of the proton. This particle, composed of two charm quarks and one down quark, is approximately four times heavier than a proton. The discovery was made possible by the upgraded LHCb detector, which allowed scientists to capture this fleeting particle in just one year of data collection.

Heavier cousin of the proton discovered at the LHC – Physics WorldLHCb Collaboration discovers new proton-like particleScience Daily

The ? cc + particle's unique quark composition makes it an important subject for testing quantum chromodynamics (QCD), the theory that describes the strong force binding quarks together. Tim Gershon, spokesperson-elect for LHCb, emphasized that the particle's structure provides an ideal opportunity to examine QCD's binding mechanisms. The particle's extremely short lifetime, less than a trillionth of a second, previously hindered its detection, but advancements in detector technology have now made this possible.

Heavier cousin of the proton discovered at the LHC – Physics WorldLHCb Collaboration discovers new proton-like particle

The upgraded LHCb detector features a silicon pixel system known as the Vertex Locator, which tracks particle paths with high precision, and a Ring Imaging Cherenkov system that identifies particle types based on emitted light. These enhancements have significantly increased the detector's data collection capabilities, enabling the observation of rare particles like the ? cc +. The statistical significance of the discovery was measured at 7 sigma, surpassing the 5 sigma threshold required for a confirmed discovery.

Heavier cousin of the proton discovered at the LHC – Physics WorldScience Daily

The ? cc + particle's existence had been hinted at over two decades ago by the SELEX experiment at Fermilab, but those findings could not be confirmed. The LHCb's recent measurement provides a clear and unambiguous detection, resolving a long-standing question in particle physics. This discovery also adds to the total number of hadrons identified by LHC experiments, which now stands at 80.

Heavier cousin of the proton discovered at the LHC – Physics WorldScience Daily

The University of Manchester played a pivotal role in the discovery, with significant contributions to the LHCb detector upgrade. Professor Chris Parkes led the UK’s involvement in the project, which included designing and building critical components of the upgraded tracking system. The university's historical significance in particle physics, dating back to the identification of the proton, continues to influence modern research.

Science DailyHeavier cousin of the proton discovered at the LHC – Physics World

Following the discovery of the ? cc +, physicists aim to measure its properties in detail, including its lifetime and decay channels. There is also interest in discovering even heavier particles, such as the ? bc and ? bb, which may require further upgrades to the LHCb detector. However, funding for these future upgrades has recently come under scrutiny, particularly concerning the UK Research and Innovation (UKRI) agency's decisions.

Heavier cousin of the proton discovered at the LHC – Physics World

Mark Thomson, CERN Director-General, remarked on the importance of the LHCb's capabilities in achieving this discovery, stating, “This major result is a fantastic example of how LHCb’s unique capabilities play a vital role in the success of the LHC.” Tim Gershon highlighted the significance of the discovery for testing QCD, noting, “Studies of particles containing two heavy quarks are very interesting for tests of the QCD binding mechanisms.”

LHCb Collaboration discovers new proton-like particleHeavier cousin of the proton discovered at the LHC – Physics World

• “The key development that made the observation possible was the upgrade of the LHCb detector,” — Tim Gershon, Spokesperson-elect for LHCb

Heavier cousin of the proton discovered at the LHC – Physics World

• “Rutherford's gold-foil experiment in a Manchester basement transformed our understanding of matter, and today's discovery builds on that legacy using state-of-the-art technology at CERN. Both milestones demonstrate just how far curiosity driven research can take us. This discovery showcases the extraordinary capability of the upgraded LHCb detector and the strength of UK and Manchester contributions to the experiment.” — Professor Chris Parkes, University of Manchester

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• “This major result is a fantastic example of how LHCb’s unique capabilities play a vital role in the success of the LHC,” — Mark Thomson, CERN Director-General

LHCb Collaboration discovers new proton-like particle

The discovery of the ? cc + particle marks a significant advancement in particle physics, paving the way for future research and exploration of the fundamental forces that govern matter.

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