Story URL: http://news.medill.northwestern.edu/chicago/news.aspx?id=229608
Story Retrieval Date: 12/22/2014 9:41:54 PM CST
Physicists announced their discovery this week of a new subatomic particle that hid for years in the debris created when subatomic particles collide at CERN.
The particle, the exotic hadron made up of two quarks and two antiquarks, lurked in the shadows of CERN's atom smasher for the last eight years, a particle that now has cleared the way for further discoveries.
CERN's Large Hadron Collider beauty experiment is part of the world's largest particle collider nestled deep beneath the border of France and Switzerland in CERN's subterranean complex scientist found evidence of a hadron, composed of two quarks and two antiquarks, hiding in the debris of the experiment's subatomic collisions.
Sheldon Stone, a co-author of the paper and a physicist at Syracuse University, said that this discovery clears up a controversy among researchers, “where some thought this structure existed and others thought it was an error in the data.” He was quick to add that “there is no controversy here anymore.”
Stone said that besides clearing up the controversy, this discovery also paves the way for further exploration. “There isn't anything more we can do with this,” Sheldon said. “The next step is to look for other structures we haven't found yet.”
Since the 1960s, the Standard Model, the general theory that explains how matter interacts, predicted and proved that the fundamental particles known then, protons, neutrons and electrons, are not the smallest that exist. Rather, these particles are composites known as hadrons, and they are made of particles called quarks.
The vast majority of hadrons, called baryons, are made of three quarks. Protons and neutrons are examples of this three-quark structure. Another classification of hadrons, called mesons, are made of a quark and an antiquark. Since antiquarks are a form of antimatter, mesons are inherently unstable and quickly decay, forming common particles like electrons and neutrinos. But in 2008, Japan's Belle particle colliding experiment found hints of a new hadron that did not exactly fit into either of these categories.
In the years since, researchers have been trying to get a better look at what Belle observed, and on Wednesday CERN published clear evidence of the exotic hadron that is made of two quarks and two antiquarks, created by single quark-antiquark mesons colliding at high speeds.
The Large Hadron Collider beauty experiment differs from CERN's more famous experiments, such as ATLAS or CMS, because the experiment observes particles colliding while going in the same direction, instead of colliding at near light speed as they travel in opposite directions. Due to this set up, the LHCb is ideal for many other experiments as well, such as exploring the world of weak interactions among particles.