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OSU scientists make ‘significant’ contributions to physics breakthrough

Wednesday, September 12, 2018

Discovery advances understanding of subatomic particles

Oklahoma State University scientists have joined a celebration among a worldwide cadre of scientists who are part of the latest discovery involving the celebrity Higgs boson subatomic particle. The August announcement of the discovery, a decade in the making, was made at the ATLAS experiment’s Large Hadron Collider (LHC) in Switzerland near Geneva, where OSU physicists, students and post-graduates work on its research teams.

The recent revelation showed that, most of the time when the Higgs decays, it transforms into even smaller particles known as bottom or b-quarks, as predicted by the Standard Model of the theory of subatomic particles.

The monumental 2012 Higgs boson discovery turned the particle into a scientific superstar because it is the most important confirmation of the Standard Model, the theory of how the universe functions at the subatomic level. Its discovery was a quantum leap in understanding how particles interact and resulted in the Nobel Prize in Physics for Peter Higgs and François Englert.

“The Standard Model is the best theory scientists have to explain the behavior of subatomic particles,” said Joseph Haley, OSU associate professor of physics. “The Higgs boson is very important because it is required for other fundamental particles to have mass.” 

It took years of experimentation, and an important contribution from OSU, to record the decay phenomena because Higgs bosons are only seen in roughly one out of a billion particle collisions in the Large Hadron Collider and exist for only one-septillionth of a second.

“You can only observe the Higgs boson through its decay, which is extremely rare — it is very short-lived,” said Sasha Khanov, associate professor of physics. Khanov, Haley and physics professor Flera Rizatdinova work in the OSU High Energy Physics (HEP) laboratory that contributed to the discovery.

OSU’s HEP group was pivotal in detecting the Higgs boson decay by developing a technique to help identify the event despite its rarity. B-tagging allows scientists to recognize the hard-to-observe Higgs decay by pinpointing signature jets of energy released by b-quarks in LHC collisions.

“The OSU High Energy Physics group made significant contributions to the development of b-tagging algorithms at ATLAS, in particular the measurement of the probability to misidentify a non-b-jet as a b-jet,” said Rizatdinova.

Khanov played a critical role in the Higgs-to-b-quark decay experiment as a member and co-chair of the project’s editorial board. He and fellow board members — scientists from around the world — analyzed data from the experiment to confirm its soundness before announcing the find to an eager scientific community and the public.

The HEP team is studying a variety of subatomic particles, including the Higgs, and searching for new particles and potential phenomena such as dark matter, a theoretical form of matter believed to make up the majority of the mass of the universe. The team uses data from the LHC, the world’s largest atom smasher at the ATLAS research complex in Switzerland. The LHC crashes particles into each other at nearly the speed of light, allowing scientists to record data from the aftermath and observe occurrences such as the Higgs decay. OSU sends graduate students and post-doctoral fellows to Europe to work at the LHC.

Haley uses LHC data to look for inconsistencies, which are believed to exist but have never been detected in the Standard Model. Dark matter would be just such an inconsistency, which Haley calls new physics.

“Any deviation in the Standard Model’s predictions of Higgs’ decay would have been evidence of new physics,” Haley said. “The reason this is interesting is that we hope to find something that disagrees with the Standard Model’s prediction. We have some evidence of physics beyond the Standard Model, like dark matter, but have not found out where it goes wrong.”

The discovery of the Higgs-to-bottom-quark phenomena is a large step forward in unlocking the secrets of the universe governing how fundamental particles behave. The participation of Oklahoma State University researchers and students in understanding the tiniest universal elements is a testament to the reach and reputation of OSU scientists.

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