Research Spotlight: CERN scientists close in on Higgs boson

high-energy physics

Research Spotlight: CERN scientists close in on Higgs boson

An event showing four muons (red tracks) from a proton-proton collision in ATLAS. This event is consistent with two Z particles decaying into two muons each. Such events are produced by Standard Model processes without Higgs particles. They are also a possible signature for Higgs particle production, but many events must be analyzed together in order to tell if there is a Higgs signal. (Image courtesy of CERN.)

In a giant game of hide and seek, physicists say there are indications they finally may have found evidence of the long sought after fundamental particle called the Higgs boson.

Researchers at Switzerland-based CERN, the largest high-energy physics experiment in the world, have been seeking the Higgs boson since it was theorized in the 1960s. The so-called “God” particle is believed to play a fundamental role in solving the important mystery of why matter has mass.

Thousands of scientists from around the world seek evidence of the Higgs particle through experiments at CERN’s Large Hadron Collider. The researchers analyze a flood of electronic data streaming from the breakup of speeding protons colliding in the massive particle accelerator. Scientists on Tuesday announced in a seminar held at CERN that they’ve found hints of the Higgs.

SMU physicist Ryszard Stroynowski“Now we have a strong indication, but not yet a confirmation, of a discovery,” said SMU physicist Ryszard Stroynowski (left), the leader of SMU’s team of scientists working on the experiment.

Theorists have predicted that some subatomic particles gain mass by interacting with other particles called Higgs bosons. The Higgs boson is the only undiscovered part of the Standard Model of physics, which describes the basic building blocks of matter and their interactions.

Higgs bosons, if they exist, are short-lived and can decay in many different ways. Just as a vending machine might return the same amount of change using different combinations of coins, the Higgs can decay into different combinations of particles. Discovery relies on observing statistically significant excesses of the particles into which they decay rather than observing the Higgs itself.

“If indeed we are able to confirm sighting of the Higgs in the months ahead, this clearly focuses our future studies,” said Stroynowski, a professor in the SMU Department of Physics. “Now by the middle of next year we’ll know for sure if this particle exists and we can begin to study its properties. This is a very big step in the understanding of particle physics.”

Besides Stroynowski, the SMU team of researchers includes three other Physics Department faculty: Jingbo YeRobert Kehoe and Stephen Sekula, six postdoctoral fellows and five graduate students. Main contributions to the new analysis of the data were made by postdoctoral researcher Julia Hoffman and graduate student Ryan Rios.

Others in the department who have contributed include former postdoctoral fellow David Joffe, now an assistant professor at Kennesaw State University, graduate students Renat Ishmukhametov and Rozmin Daya and theoretical faculty Fredrick Olness and Pavel Nadolsky.

Stroynowski, Hoffman, and Rios are among the more than 70 scientists whose work directly contributed to the conference papers reporting the findings, said Olness, a professor and chairman of the SMU Department of Physics. While thousands of scientists worldwide participated directly and indirectly in the experiments, SMU is one of only a few U.S. universities whose scientists are named among the 70 researchers directly cited on one of the three conference papers.

“SMU’s role in the LHC experiments provides our students a chance to participate in pioneering discoveries,” Olness said. “SMU students helped build the ATLAS detector, they were in the control room when the experiment started up, and they contributed to the analysis. The results presented today are historic, and they will help shape our view of the matter and forces that comprise our universe; SMU students have played a role in this achievement.”

SMU's Ryszard Stroynowski and Ryan Rios

In Fondren Science Building, physicist and SMU Physics Professor Ryszard Stroynowski and physics graduate student Ryan Rios discuss the Higgs boson after viewing a CERN web cast Tuesday announcing evidence of the Higgs. (Photo by Hillsman S. Jackson.)

Discovering the type of Higgs boson predicted in the Standard Model would confirm a theory first put forward in the 1960s.

“This year, the LHC has come roaring into the front of the hunt for the Higgs boson and may be poised to either identify it, or refute its existence, in the coming months,” said Kehoe, associate professor in the SMU Department of Physics. “As I like to tell my students learning modern physics, ‘You still live in a world in which we do not know for sure the mechanism breaking the symmetry between electromagnetic and weak interactions. That world may be soon to change forever. We may soon see a truly new thing.’”

– Written by Margaret Allen

> Read the full story at the SMU Research blog

December 14, 2011|News|

Research Spotlight: Top quark helps in hunt for Higgs boson

Standard Model fundamental particlesNew high-energy particle research by a team working with data from Fermi National Accelerator Laboratory further heightens the uncertainty about the exact nature of a key theoretical component of modern physics – the massive fundamental particle called the Higgs boson.

Analysis of data from particle collisions resulting in two leptons helps improve measurements of the mass of another heavy subatomic particle called the top quark, says SMU physicist Robert Kehoe, who led the team that calculated the measurement.

Improving the measurement of the mass of the top quark bears on the nature of the Higgs, says Kehoe, an assistant professor in SMU’s Department of Physics.

The Higgs was postulated in the 1960s to help explain how basic elements of the universe fit together and interact. It is responsible for a phenomenon called the Higgs mechanism, which gives mass to the fundamental particles of nature.

Physicists have searched for more than four decades to observe the never-before-seen Higgs. Now they hope it will be observed in the next few years since data started flowing recently from the world’s newest and largest high-energy particle accelerator, the CERN laboratory’s Large Hadron Collider near Geneva, Switzerland.

Researchers theorize that the top quark – because of its sizable mass – is sensitive to the Higgs and therefore may point to it. They theorize that knowing the mass of the top quark narrows the range of where the Higgs will be detected in CERN’s LHC collisions. The top quark is one of 16 species of subatomic particles that physicists have observed. It was predicted in the 1970s and observed in 1995. Increasingly precise measurements of its mass have been achieved almost every year since, and physicists closely watch the incremental measurements of the top quark.

The two-lepton analysis by Kehoe and SMU post-doctoral researcher Peter Renkel looked at data taken over four years during high-energy collisions at Fermilab, a Department of Energy proton-antiproton collider in Batavia, Illinois.

The two-lepton analysis is one of almost a dozen analyses of the mass of the top quark at a Fermilab experiment called “DZero.” The DZero experiment involves 500 physicists and is one of Fermilab’s two large experimental collaborations of scientists. The top quark mass was first observed simultaneously by these two experiments. Several measurements of the top quark’s mass from these two experiments are combined to a “world average” value.

The new world average is so precise that it constrains more tightly than ever the range of possible measurements for the mass of the Higgs, Kehoe says.

If the Higgs does prove different than currently expected, physicists may have to rework their long-standing theoretical framework, known as the Standard Model. Scientists worldwide are hoping to validate the Standard Model – which has worked well for more than 30 years to explain everything from radioactivity to computer chips – by actually observing the Higgs.

“The new results may be an indication that the Higgs boson has different properties than the Standard Model indicates,” Kehoe says. “It’s very difficult to devise a theory without some mechanism that mimics fairly well the Higgs mechanism. But if the underlying cause of this mechanism is significantly different, that will have a major impact on the fundamentals of the Standard Model. It could point to something deeper than the standard Higgs boson at work, and that is very interesting.”

(Above, a Fermilab graphic depicting the Standard Model fundamental particles.)

Read more at the SMU Research blog

December 8, 2009|Research|

For the Record: Dec. 4, 2009

Philip Van Keuren, 'Allee II Woman III'Philip Van Keuren, Art, Meadows School of the Arts, is featured in a current exhibition at The McKinney Avenue Contemporary, a noted Dallas gallery of contemporary art. The exhibition, titled “Philip Van Keuren: Forty Years of Works on Paper, 1969-2009,” features a selection of his collages, drawings and photographs and will be on view at The Mac through Dec. 19. Recently, he was interviewed on WRR-FM’s “Art Matters” about his artistic work and his career. (Right, a section of Van Keuren’s 2009 diptych Allee II Woman III, Iris print.)

SMU’s chapter of the Public Relations Student Society of America (PRSSA) won three 2009 Frederick H. Teahan Awards at the PRSSA National Conference held in San Diego in November. The team won a total of $800, as well as two plaques and a trophy. Entries for the Teahan awards are submitted from among the 300 PRSSA chapters at colleges and universities nationwide. SMU won in every category it entered.

The University received top honors for Outstanding Chapter Development and Outstanding PRSA/PRSSA Chapter Relationship. Faculty adviser Christy Baily-Byers, Corporate Communications and Public Affairs, Meadows School of the Arts, received the Outstanding Faculty Advisor Award for her “dedication and creative chapter guidance, effective student motivation, exceptional contributions to public relations education, supportive chapter advocacy and representation within the academic department and with the PRSA sponsoring chapter and its members.”

Steve Sekula, Physics, Dedman College, has been named to membership in the BaBar Collaboration, a group of about 600 physicists and engineers from 75 institutions in 10 countries who study the subatomic particles called B mesons produced by the PEP-II storage ring in the BaBar detector at Stanford University. His efforts will focus on physics research and publications. In addition, he will publish a paper on a search for invisible decays of the Upsilon(1S) meson in Physical Review Letters. The process may be sensitive to the presence of either low-mass dark matter or a low-mass dark gauge boson. The paper is available in a preprint version online.

December 4, 2009|For the Record|
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