Two experiments at CERN's Large Hadron Collider made a discovery that links the two heaviest elementary particles of the Standard Model: the Higgs boson and top quark.
CMS And Atlas Experiments
Scientists working in the CMS and ATLAS experiments saw simultaneous production of these two particles during a rare subatomic process, marking the first time scientists measured the direct interaction between Higgs boson and top quarks.
The rare process involves two gluons inside the colliding protons fusing and producing two virtual top quarks.
Interaction Of Higgs Boson And Top Quarks
Fundamental particles gain mass when they interact with the Higgs field, so it is not surprising that the top quark would be observed to have strong coupling with the Higgs boson. Scientists, however, said that the theory still needs to be carefully scrutinized.
The Higgs boson was first predicted in the 1960s, but it was only in 2012 that it was discovered by the CMS and ATLAS experiments. By this time, theorists already have an idea how the Higgs boson should behave based on the Standard Model of particle physics.
Physicists now tap the LHS to test these predictions. Among those they want to investigate are whether Higgs boson can interact with quarks and what the relationship may look like.
Researchers are interested in the Higgs boson-top quark relationship because the top quark is the most massive particle that scientists have discovered.
"As the 'giver of mass,' the Higgs boson should be enormously fond of the top quark," Patty McBride, from the U.S. Department of Energy's Fermi National Accelerator Laboratory, said.
Earlier evidences failed to meet the threshold needed to claim discovery of coupling, but results of the new experiments, which were published in the Physical Review Letter, showed that the Higgs boson definitely communicates with the top quark.
Scientists were able to observe a statistically significant abundance of events in which the production of the Higgs boson is associated with two top quarks.
"The observation of Higgs boson production in association with a top quark-antiquark pair is reported, based on a combined analysis of proton-proton collision data," researchers wrote in their study.
Physics Beyond The Standard Model
Scientists said that exploring the relationship of the Higgs boson and the top quark further may lead to new physics beyond the standard model.
"In the coming years, much more data will be collected and the precision will be improved, in order to see if the Higgs boson reveals the presence of physics beyond the Standard Model," said Florencia Canelli, from the Department of Physics at the University of Zurich.
