What’s next for particle physicists, post-​​Higgs?

by Angela Herring

In March of last year, sci­en­tists working with the Large Hadron Col­lider at the Euro­pean Orga­ni­za­tion for Nuclear Research in Geneva, Switzer­land, iden­ti­fied the Higgs boson, the last elu­sive par­ticle in the Stan­dard Model of physics. The Higgs par­ticle, said North­eastern assis­tant pro­fessor of physics Toyoko Ori­moto, one of the sci­en­tists on the team, can be used to explain how ele­men­tary par­ti­cles acquire mass. “Before the dis­covery of the Higgs boson, the Stan­dard Model was like a puzzle with one piece missing,” she said, “and you kind of know what that piece will look like.”

Ori­moto hopes the Large Hadron Col­lider will be able to address many more unan­swered ques­tions in physics. “The Higgs par­ticle is inter­esting,” she said, “but what really cap­tures my imag­i­na­tion is thinking about pos­si­bil­i­ties beyond the Stan­dard Model.”

Backed by an Early Career Award from the Depart­ment of Energy, Ori­moto hopes to begin exploring those other possibilities.

For her, the two biggest ques­tions still left unan­swered by the Stan­dard Model are gravity and dark matter. “Dark matter and dark energy make up more than 95 per­cent of the uni­verse, and yet the Stan­dard Model doesn’t address them,” she said.

Dark matter was hypoth­e­sized to explain the large dis­crep­an­cies between the grav­i­ta­tional behavior of large astro­nom­ical objects and the amount of detectable matter they con­tain. Physi­cists sus­pect that dark matter is made up of ele­men­tary par­ti­cles that are dif­fi­cult to observe in the lab­o­ra­tory because of their weak interactivity.

Gravity is a more well-​​know force, but it’s also extremely weak for unknown rea­sons, Ori­moto said. You can get a sense of its weak­ness, she explained, by coun­ter­acting earth’s grav­i­ta­tional pull on a tiny paper­clip by moving it with a single magnet. While clas­sical physics does a fine job of explaining how gravity works on a macro­scopic scale, things fall apart when par­ticle physi­cists try to under­stand it at the quantum level.

One of the most com­pelling the­o­ries often used to explain anom­alies such as dark matter and the weak­ness of gravity, Ori­moto said, is super­sym­metry, wherein all of the par­ti­cles described in the Stan­dard Model have a super­sym­metric “brother” par­ticle. In super­sym­metry, there are also mul­tiple Higgs bosons, a fact that Ori­moto and her col­leagues at the LHC plan to leverage as they begin to probe deeper into the behavior of the newly dis­cov­ered Higgs.

The researchers will take a closer look at the Higgs’ behavior using hordes of data col­lected at the LHC. If some of its prop­er­ties cannot be explained by the Stan­dard Model, Ori­moto said, then  super­sym­metry or some other new theory of physics could be at work.

She can’t wait to inves­ti­gate. “I started to get inter­ested in the idea that every­thing in the uni­verse was made up of this small set of ele­men­tary par­ti­cles and that blew my mind,” said Ori­moto, recalling the moment in the 1990s when sci­en­tists announced the dis­covery of the top quark, the heav­iest of the ele­men­tary par­ti­cles in the Stan­dard Model. “And it hasn’t stopped blowing my mind.”

Originally published in news@Northeastern on July 16, 2013

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