JUL 12, 2017 6:00 AM PDT

The Discovery of Xi-cc an Exotic and Charming Particle

WRITTEN BY: Daniel Duan

On July 6, a team of researchers from the European Organization for Nuclear Research (CERN) announced that they confirmed the observation of a theoretically predicted particle called Xi-cc (the "Xi" is pronounced "ksi"). The newly discovered particle has a mass 3,621 MeV (million electron volts), almost four times the mass of a proton (938 MeV). This heavy particle is made of two charm quarks and an up quark. As comparison, a proton is made of two up quarks and a down quark. The observation of Xi-cc was made possible thanks to the high production rate of heavy quarks at the Large Hadron Collider (LHC) and the unique capabilities of the LHCb experiment (a collaboration dedicated for studies on matter-antimatter asymmetry), which identify the disintegration of protons with excellent efficiency.

Envisioned image of the Xi-cc particle, made of two charm quarks and one up quark. Credit: CERN

The Xi-cc particle is a type of baryon. According to the standard model of physics, a baryon is a particle composed of three quarks or a triquark. The name "baryon" comes from the Greek word for "heavy", since at the time of naming most known elementary particles are lighter in masses. The baryons that most of us familiar with are protons and neutrons, which make up everyday matter.

Standard Model of Elementary Particles. Credit: Wikipedia

In the standard model, there are six types of quarks, and a random mix of three that involves at least one charm quark can theoretically form a great variety of baryons. The baryons observed in previous experiments contain only one heavy quark. The discovery of Xi-cc confirmed for the first time that baryons with two heavy quarks exists for real. Therefore, the Xi-cc is also dubbed a “doubly charmed” particle.

Related: the standard model of physics

According to Giovanni Passaleva the spokesperson of the LHCb team, “finding a doubly heavy-quark baryon is of great interest as it will provide a unique tool to further probe quantum chromodynamics, the theory that describes the strong interaction, one of the four fundamental forces. Such particles will thus help us improve the predictive power of our theories.”

Scientist had long predicted the existence of Xi-cc but without clear idea of its mass. Some physicists such as Jonathan Rosner, an emeritus professor from the University of Chicago had predicted a theoretical mass for the Xi that is close to the CERN team discovery. An earlier experiment at Fermi National Accelerator Laboratory caught a glimpse of Xi-cc back in 2002, but the data estimated a mass that was 100 MeV lower. The results from LHCb confirmed the prediction was correct, which also acts as a confirmation of the standard model.

What is the dynamics inside the Xi-cc particle like? Physicists suggest we should look up the sky for answer. "In contrast to other baryons, in which the three quarks perform an elaborate dance around each other, a doubly heavy baryon is expected to act like a planetary system, where the two heavy quarks play the role of heavy stars orbiting one around the other, with the lighter quark orbiting around this binary system," explained Guy Wilkinson, a former spokesperson for LHCb.

 

The LHCb Experiment Credit: CERN

 

Source: CERN/Live Science

 

About the Author
  • Graduated with a bachelor degree in Pharmaceutical Science and a master degree in neuropharmacology, Daniel is a radiopharmaceutical and radiobiology expert based in Ottawa, Canada. With years of experience in biomedical R&D, Daniel is very into writing. He is constantly fascinated by what's happening in the world of science. He hopes to capture the public's interest and promote scientific literacy with his trending news articles. The recurring topics in his Chemistry & Physics trending news section include alternative energy, material science, theoretical physics, medical imaging, and green chemistry.
You May Also Like
OCT 02, 2020
Chemistry & Physics
A New Way of Building Houses: 3-D Printing with Clay
OCT 02, 2020
A New Way of Building Houses: 3-D Printing with Clay
Our ancestors had a long history of building dwelling structures using clay and plant-based fibrous materials. Even thes ...
OCT 22, 2020
Chemistry & Physics
NASA Looks to Nuclear Fusion for Powering Deep Space Missions
OCT 22, 2020
NASA Looks to Nuclear Fusion for Powering Deep Space Missions
Nuclear fusion is the frontier of energy research, and NASA has a plan to bring this state-of-the-art power source to th ...
OCT 23, 2020
Chemistry & Physics
Expanding on Einstein's theory of time dilation
OCT 23, 2020
Expanding on Einstein's theory of time dilation
Research published recently in the journal Nature Communications considers the influence of the quantum mechanics c ...
OCT 28, 2020
Cell & Molecular Biology
Mimicking Cells With a Microfluidic Chip
OCT 28, 2020
Mimicking Cells With a Microfluidic Chip
Cell culture models are one way for scientists to learn more about biology. But cells grow in large cultures that are of ...
DEC 23, 2020
Chemistry & Physics
Fiber optic cables manufactured under pressure reduce signal loss
DEC 23, 2020
Fiber optic cables manufactured under pressure reduce signal loss
New research from Penn State and AGC Inc. in Japan reports that the silica glass used in fiber optic cables would be mor ...
JAN 17, 2021
Space & Astronomy
New Way to Extract Energy from Black Holes
JAN 17, 2021
New Way to Extract Energy from Black Holes
In his theory of general relativity, Einstein predicted that black holes harbor an enormous amount of energy. And now, r ...
Loading Comments...