SMU scientists celebrate Nobel Prize for Higgs discovery

Higgs boson

SMU scientists celebrate Nobel Prize for Higgs discovery

Particle collision from the ATLAS ExperimentSMU’s experimental physics group played a pivotal role in discovering the Higgs boson — the particle that proves the theory for which two scientists have received the 2013 Nobel Prize in Physics.

The Royal Swedish Academy of Sciences today awarded the Nobel Prize to theorists Peter W. Higgs and François Englert to recognize their work developing the theory of what is now known as the Higgs field, which gives elementary particles mass. U.S. scientists played a significant role in advancing the theory and in discovering the particle that proves the existence of the Higgs field, the Higgs boson.

The Nobel citation recognizes Higgs and Englert “for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles, and which recently was confirmed through the discovery of the predicted fundamental particle, by the ATLAS and CMS experiments at CERN’s Large Hadron Collider.”

“A scientist may test out a thousand different ideas over the course of a career. If you’re fortunate, you get to experiment with one that works,” says SMU physicist Ryszard Stroynowski, a principal investigator in the search for the Higgs boson. As the leader of an SMU Department of Physics team working on the experiment, Stroynowski served as U.S. coordinator for the ATLAS Experiment’s Liquid Argon Calorimeter, which measures energy from the particles created by proton collisions.

The University’s experimental physics group has been involved since 1994 and is a major contributor to the research, the heart of which is the Large Hadron Collider particle accelerator on the border with Switzerland and France.

Preliminary discovery results were announced July 4, 2012 at CERN, the European Organization for Nuclear Research, near Geneva, Switzerland, and at the International Conference of High Energy Physics in Melbourne, Australia.

• Several contributors from SMU have made their mark on the project at various stages, including current Department of Physics faculty members Ryszard Stroynowski, Jingbo Ye, Robert Kehoe and Stephen Sekula. Faculty members Pavel Nadolsky and Fred Olness performed theoretical calculations used in various aspects of data analysis.

• University postdoctoral fellows on the ATLAS Experiment have included Julia Hoffmann, David Joffe, Ana Firan, Haleh Hadavand, Peter Renkel, Aidan Randle-Conde, Daniel Goldin and Sami Kama.

• SMU has awarded eight Ph.D. and seven M.S. degrees to students who performed advanced work on ATLAS, including Ryan Rios, Rozmin Daya, Renat Ishmukhametov, Tingting Cao, Kamile Dindar, Pavel Zarzhitsky and Azzedin Kasmi.

• Significant contributions to ATLAS have also been made by SMU faculty members in the Department of Physics’ Optoelectronics Lab, including Tiankuan Liu, Annie Xiang and Datao Gong.

“The discovery of the Higgs is a great achievement, confirming an idea that will require rewriting of the textbooks,” Stroynowski says. “But there is much more to be learned from the LHC and from ATLAS data in the next few years. We look forward to continuing this work.”

> Read the full story from SMU News

October 8, 2013|News, Research|

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|
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