Rios was a graduate student in the SMU Department of Physics and as part of a team led by SMU Physics Professor Ryszard Stroynowski spent from 2007 to 2012 as a member of the ATLAS experiment at Switzerland-based CERN’s Large Hadron Collider, the largest high-energy physics experiment in the world. Rios and the SMU team were part of the successful search for the Higgs boson fundamental particle.
Rios is now a senior research engineer for Lockheed Martin at NASA’s Johnson Space Center.
By Glenn Roberts Jr.
As a member of the ATLAS experiment at the Large Hadron Collider, Ryan Rios spent 2007 to 2012 surrounded by fellow physicists.
Now, as a senior research engineer for Lockheed Martin at NASA’s Johnson Space Center, he still sees his fair share.
He’s not the only scientist to have made the leap from experimenting on Earth to keeping astronauts safe in space. Rios works on a small team that includes colleagues with backgrounds in physics, biology, radiation health, engineering, information technology and statistics.
“I didn’t really leave particle physics, I just kind of changed venues,” Rios says. “A lot of the skillsets I developed on ATLAS I was able to transfer over pretty easily.”
The group at Johnson Space Center supports current and planned crewed space missions by designing, testing and monitoring particle detectors that measure radiation levels in space.
Massive solar flares and other solar events that accelerate particles, other sources of cosmic radiation, and weak spots in Earth’s magnetic field can all pose radiation threats to astronauts. Members of the radiation group provide advisories on such sources. This makes it possible to warn astronauts, who can then seek shelter in heavier-shielded areas of the spacecraft.
Johnson Space Center has a focus on training and supporting astronauts and planning for future crewed missions. Rios has done work for the International Space Station and the robotic Orion mission that launched in December as a test for future crewed missions. His group recently developed a new radiation detector for the space station crew.
Rios worked at CERN for four years as a graduate student and postdoc at Southern Methodist University in Dallas. At CERN he was introduced to a physics analysis platform called ROOT, which is also used at NASA. Some of the particle detectors he works with now were developed by a CERN-based collaboration.
Fellow Johnson Space Center worker Kerry Lee wound up a group lead for radiation operations after using ROOT during his three years as a summer student on the Collider Detector at Fermilab, or CDF experiment.
SMU’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.”
In the 1960s, Higgs and Englert, along with other theorists, including Robert Brout, Tom Kibble and Americans Carl Hagen and Gerald Guralnik, published papers introducing key concepts in the theory of the Higgs field. In 2012, scientists on the international ATLAS and CMS experiments, performed at the Large Hadron Collider at CERN laboratory in Europe, confirmed this theory when they announced the discovery of the Higgs boson.
“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.
SMU joins nearly 2,000 physicists from U.S. institutions — including 89 U.S. universities and seven U.S. Department of Energy laboratories — that participate in the ATLAS and CMS experiments, making up about 23 percent of the ATLAS collaboration and 33 percent of CMS at the time of the Higgs discovery. Brookhaven National Laboratory serves as the U.S. hub for the ATLAS experiment, and Fermi National Accelerator Laboratory serves as the U.S. hub for the CMS experiment. U.S. scientists provided a significant portion of the intellectual leadership on Higgs analysis teams for both experiments.
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.
“It is an honor that the Nobel Committee recognizes these theorists for their role in predicting what is one of the biggest discoveries in particle physics in the last few decades,” said Fermilab Director Nigel Lockyer. “I congratulate the whole particle physics community for this achievement.”
The majority of U.S. scientists participating in LHC experiments work primarily from their home institutions, remotely accessing and analyzing data through high-capacity networks and grid computing. The United States plays an important role in this distributed computing system, providing 23 percent of the computing power for ATLAS and 40 percent for CMS. The United States also supplied or played a leading role in several main components of the two detectors and the LHC accelerator, amounting to a value of $164 million for the ATLAS detector, $167 million for the CMS detector, and $200 million for the LHC. Support for the U.S. effort comes from the U.S. Department of Energy Office of Science and the National Science Foundation.
“It’s wonderful to see a 50-year-old theory confirmed after decades of hard work and remarkable ingenuity,” said Brookhaven National Laboratory Director Doon Gibbs. “The U.S. has played a key role, contributing scientific and technical expertise along with essential computing and data analysis capabilities — all of which were necessary to bring the Higgs out of hiding. It’s a privilege to share in the success of an experiment that has changed the face of science.”
The discovery of the Higgs boson at CERN was the culmination of decades of effort by physicists and engineers around the world, at the LHC but also at other accelerators such as the Tevatron accelerator, located at Fermilab, and the Large Electron Positron accelerator, which once inhabited the tunnel where the LHC resides. Work by scientists at the Tevatron and LEP developed search techniques and eliminated a significant fraction of the space in which the Higgs boson could hide.
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 and Daniel Goldin.
SMU has awarded eight Ph.D. and seven M.Sc. 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.”
Higgs and Englert published their papers independently and did not meet in person until the July 4, 2012, announcement of the discovery of the Higgs boson at CERN. Higgs, 84, is a professor emeritus at the University of Edinburgh in Scotland. Englert, 80, is a professor emeritus at Universite Libre de Bruxelles in Belgium.
The prize was announced at 5:45 a.m. CDT on Tuesday, Oct. 8, 2013.
SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information see www.smu.edu.
SMU has an uplink facility located on campus for live TV, radio, or online interviews. To speak with an SMU expert or book an SMU guest in the studio, call SMU News & Communications at 214-768-7650.
Physicists from SMU and around the globe were euphoric Wednesday with the revelation that a new particle consistent with the Higgs boson “God particle” has been observed.
Described as a great triumph for science, the observation is the biggest physics discovery of the last 50 years and opens what scientists said is a vast new frontier for more research.
The achievement is the result of the global CERN scientific collaboration of thousands of scientists, including physicists from SMU, and CERN’s massive $10 billion Large Hadron Collider proton smasher.
“The observation opens up clear directions for physicists at SMU and throughout the world to study the properties of the Higgs,” said SMU physicist Ryszard Stroynowski, a principal investigator in the search for the Higgs and the leader of SMU’s team from the Department of Physics on the experiment.
“The experimental physics group at SMU has been involved since 1994 and is a major contributor to this study. This discovery was many years in the making, but it was worth the wait,” Stroynowski said.
The results, which are preliminary, were announced at CERN, the European Organization for Nuclear Research, near Geneva, Switzerland, and at the International Conference of High Energy Physics in Melbourne, Australia.
SMU at CERN
SMU researchers at CERN for the Higgs unveiling included Tingting Cao, Renat Ishmukhatemov, Aidan Randle-Conde, Stephen Sekula and Julia Hoffman. (Credit: Tingting Cao)
SMU Dean of Dedman College of Humanities and Sciences William M. Tsutsui noted that the crucial work contributed by SMU scientists gives Dallas standing in the discovery.
“Although the world’s eyes are on Switzerland, it is important to remember how much of the expertise driving the revolutionary experiments at CERN came from right here in Dallas,” Tsutsui said. “Distinguished scholars in Dedman College’s Department of Physics, including Ryszard Stroynowski and Jingbo Ye, have played critical roles in the search for the tiniest and most elusive building blocks of the universe.”
Observation is culmination of nearly 50 years of research In making the announcement, CERN’s scientists stopped short of declaring the new particle the Higgs, saying they will further analyze the data to see whether it is the Higgs boson as originally theorized more than 40 years ago, but which has never been observed through experiments.
A Higgs particle is necessary to round out the fundamental particles that make up physics’ Standard Model, which describes the fundamental particles and their interactions.
Without a Higgs, the Standard Model does not fully explain how the universe emerged from the Big Bang. The Higgs explains how matter acquires mass.
CERN’s Large Hadron Collider along the border of France and Switzerland made it possible to observe evidence of the Higgs by smashing together protons at high energies so their breakup replicates the Big Bang. The LHC, which took a decade to build, started operation in 2010. It is home to the largest high-energy physics experiments in the world, including the ATLAS and CMS particle detectors, which supplied the data for Wednesday’s results.
Scientists from 45 collaborating nations work on the LHC experiments, including more than 1,700 from 89 U.S. universities. They have helped design, build and operate the LHC accelerator and its particle detectors.
LHC’s data equivalent to grains of sand needed to fill Olympic-size pool The LHC is a 17-mile tunnel some 100 meters below ground. Within the tunnel, billions of protons are sent hurling into one another to re-create the high-energy explosions present at the Big Bang. In those rare instances when protons collide in the LHC tunnel, the smashing protons break up into smaller particles. In a process akin to reverse engineering, the resulting particle sprays are captured as data that are then analyzed for evidence that they emerged from the fundamental Higgs.
In announcing the results, CERN scientists said data taken the past two years represent 500 trillion collisions. That equates to the grains of sand it would take to fill an Olympic-size swimming pool. Within that data, evidence pointing to the Higgs equals an amount of sand covering the tip of a finger, they said.
Discovery made possible by global supercomputing grid that includes SMU Credit for the discovery goes not only to the scientists and to CERN’s Large Hadron Collider, but also to a vast worldwide computing grid at partnering institutions. Physicists rely on supercomputers to assist their analysis of the massive flow of raw data containing the Higgs.
The SMU High-Performance Computing system is part of that grid and routinely runs data that contributed to the observation, Stroynowski said.
“Much of the success of our small group in the highly competitive environment of a large international collaboration has been due to an easy access and superb performance of the SMU High Performance Computing system,” Stroynowski said. “We used the HPC for fast data analyses and complex calculations needed for the discovery.”
Discovery of the new particle demonstrates the importance of basic research, said James Quick, associate vice president for research at SMU and dean of graduate studies.
“SMU is proud and excited that its Department of Physics has been an active participant in this effort and looks forward to the department’s continued participation at CERN,” he said. “Launched by a federal research project sponsored by Congressman Pete Sessions, high-performance computing at SMU played a role in the Higgs discovery and is a primary focus in the university’s drive to expand research and enhance education.”
Discovery is once-in-a-lifetime milestone for SMU researchers SMU researchers contribute to the experiment through hardware and software development, as well as by taking operations shifts, both in the control room and in the United States, by remote, and through review of their colleagues’ work.
“It’s a very happy day for all of us in particle physics,” said Nadolsky, who with other physicists contributed calculations extensively used by LHC experimentalists, including for discovery of the Higgs boson candidate and for ongoing analyses to establish the properties of the new particle. Those working with him include postdoctoral researchers Marco Guzzi and Jun Gao, graduate student Zhihua Liang, and senior lecturer Simon Dalley.
Other researchers who have participated on the SMU team include Ana Firan, Haleh Hadavand, Sami Kama, Aidan Randle-Conde, Peter Renkel, Rozmin Daya, Renat Ishmukhametov, Tingting Cao and Kamile Dindar-Yagci.
Electronics development was carried out by research professors Andy Liu and Annie Xiang, with computer support by Justin Ross.
“The discovery of the Higgs is a once-in-a-lifetime event; this is the culmination of a 50-year quest,” said Olness, chair of the SMU Physics Department. “The last time a discovery of this import occurred was in 1983 with the observation of the W and Z boson — also at CERN; this achievement was recognized with the 1984 Nobel Prize. Many speculate the discovery of the Higgs boson also merits a Nobel Prize.”
The vast majority of U.S. scientists participate in the LHC experiments from their home institutions, remotely accessing and analyzing the data through high-capacity networks and grid computing.
“The results released on July 4 are truly a ‘team effort,’ not just by SMU but throughout all of ATLAS,” said Sekula, assistant physics professor. “These results are not possible without both the cooperation and competition that are needed to drive scientific innovation and progress.”
Waiting for Higgs for more than half a century Physicists theorized in 1964 the existence of a new particle, now known as the Higgs, whose coupling with other particles would determine their mass.
SMU’s Kehoe said the observation changes our view of the universe. “It further transforms our daily experience of mass, which is hard and heavy, into the ghostly world of quantum mechanical interactions,” Kehoe said. “If what we are seeing is the Higgs particle, we will have identified the last unknown particle in the Standard Model.”
The Standard Model of particle physics has proved to explain correctly the elementary particles and forces of nature through more than four decades of experimental tests. But it cannot, without the Higgs boson, explain how most of these particles acquire their mass, a key ingredient in the formation of our universe.
CERN reported that both the ATLAS and CMS experiments within the LHC independently observed the new heavy particle in the mass region around 125-126 billion electron volts.
“So far, more than one study indicates an excess, but by a bit more than expected,” Kehoe said. “And the mass is in the range predicted for a Standard Model Higgs. However, measurements from other analyses need also to be brought to bear.”
The preliminary results announced Wednesday are based on data collected in 2011 and 2012, with the 2012 data still under analysis. A more complete picture will emerge later this year after the LHC provides more data.
Scientists to gather more data to learn about new particle Sekula, who was at CERN and live-blogged Wednesday’s announcement, reported that “the atmosphere in the Main Amphitheater at CERN was electric, and all this energy burst forth in thunderous applause when first CMS, then ATLAS, showed independent and overwhelming evidence for the existence of a new particle in nature, consistent with the Higgs particle. Decades of scientific hope and frustration suddenly turned to joy and excitement — I can only imagine what the future holds as we gather more data and learn more about this particle.”
The CMS and ATLAS experiments in December announced seeing tantalizing hints of a new particle in their hunt for the Higgs. Since resuming data-taking in March 2012, the CMS and ATLAS experiments have more than doubled their collected data.
In the future, physicists will have to determine the properties of the new particle.
“How much does it weigh precisely? What are its quantum mechanical properties?” Kehoe said. “There are several theories that are consistent with what we’ve seen so far, like the theory of supersymmetry, and we need to make careful measurements to tell which one is correct. If what we’re seeing is a new type of particle that only superficially resembles the Higgs right now, then this will revolutionize our understanding of matter and energy at a fundamental level.” — Margaret Allen, CERN, Fermilab
SMU is a nationally ranked private university in Dallas founded 100 years ago. Today, SMU enrolls nearly 11,000 students who benefit from the academic opportunities and international reach of seven degree-granting schools. For more information see www.smuresearch.com.
SMU has an uplink facility located on campus for live TV, radio, or online interviews. To speak with an SMU expert or book an SMU guest in the SMU Broadcast Studio, call SMU News & Communications at 214-768-7650.
Subatomic particle can explain why matter has mass
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. (article continued below)
“It doesn’t matter how beautiful your theory is, it doesn’t matter how smart you are. If it doesn’t agree with experiment, it’s wrong.” — physicist Richard Feynman
By Fredrick Olness
Chairman and Professor
SMU Department of Physics
A 50 year search for the origin of particle mass nears an end. Maybe.
Mass is a seemingly simple property of everyday objects — atoms, humans, coffee cups. Yet, to understand the origin of mass on a fundamental level has been a challenging problem with a long history. The solution to this problem, suggested nearly 50 years ago, was the Higgs Boson (or just Higgs, for short). However, it has yet to be discovered.
On Tuesday, Dec. 13, 2011, an end to the Higgs search appeared much closer when the CERN Laboratory in Geneva, Switzerland presented the latest results from the Large Hadron Collider (LHC) in a colloquium broadcast around the globe on the World Wide Web.
The announcement was a joint presentation by researchers from ATLAS and CMS, the two largest independent experiments at the LHC, in which they presented evidence for the Higgs based on the results of their 2011 data set.
Both the ATLAS and CMS experiments observed evidence for the Higgs. While the evidence was significant, it was not yet sufficient to claim an unambiguous discovery; however, it is quite compelling that the Higgs mass range obtained by these two independent experiments is consistent.
These results represent a tremendous step forward in explaining why fundamental particles have mass, and whether the Higgs exists.
What is the Higgs boson?
The postulated Higgs boson is responsible for giving mass to the many fundamental particles that make up the universe. This includes the quarks that comprise protons and neutrons, which comprise atoms and molecules, which comprise humans and everything around them. In essence, the Higgs generates the mass of the fundamental particles that make up you and your coffee cup.
We know objects have mass — just lift a heavy suitcase or weigh yourself on a scale. But to explain this seemingly simple idea in the context of our current fundamental theories has been a struggle ever since the idea of the Higgs was introduced 50 year ago. The problem is that to give particles mass in a straightforward manner would spoil a particular symmetry of the theory known as the “gauge symmetry.” Who cares? you ask, and why should I be worried about symmetry?
Symmetries have been an important guiding aspect of physics dating back before Einstein, who used symmetry principles, in part, to conclude that “all reference frames are created equal,” which led to his Theory of Relativity — certainly one of the triumphs of the 20th Century.
And that is what is so special about the Higgs; it gives particles a mass without violating the rules of symmetry.
How does the Higgs solve the problem?
According to our current understanding, Higgs bosons permeate all of space. As fundamental particles move through space, Higgs bosons interact with the particles and effectively exert a drag on them; it is this drag effect which we interpret as the mass of the particle.
Consider the following experiment. First move your coffee cup through the air, and then repeat this motion underwater; the water provides more resistance on the cup and it “feels more massive” as you drag it through the water as compared to the air. It is the interaction between the water and the coffee cup that provides the resistance to motion of mass. In this analogy, the water is playing the role of the Higgs.
It is the same with a quark, one of the fundamental particles that matter is made from. As a quark moves through space it interacts with the Higgs, and this interaction exerts a drag on the quark so that it “feels heavy.” But this is an illusion; in the strict interpretation of the theory, the quark has “mass” only because of the interaction with the Higgs that simulates the effects of the weight.
DÉJÀ VU: Luminiferous aether
To recap, the current theoretical picture is that Higgs bosons are everywhere. They permeate all space, and they must exist so that fundamental particles (that make up you and your coffee cup) have mass.
Have we seen this situation before?
In the late 1800’s, physicists posited the existence of a “luminiferous aether” which permeated all space. Scientists knew that water waves traveled through water, sound waves through air, and so they believed that light waves also needed something to travel through; luminiferous aether was invented to serve this purpose and get the “right” answer. There were many experiments that gave indirect evidence for the aether; however, all attempts to directly measure it were unsuccessful. Eventually it was demonstrated that the luminiferous aether did not exist, and this paved the way for Einstein to show that it was unnecessary and to present an alternative, his theory of relativity.
Thus, the non-existence of luminiferous aether actually led to more fantastic discoveries than if it had been proven.
Direct vs. indirect evidence
So we come to the central question: does the Higgs exist?
There is ample indirect evidence that the Higgs exists. We know that fundamental particles have mass, and we believe this mass is due to particle interactions with Higgs bosons. Over the past 50 years physicists have performed a variety of sophisticated experiments, and they all point to the existence of the Higgs.
However, in many ways the Higgs is a contrived solution; inelegant, introduced into the theory because so far there has been no better way to get the right answer — that particles have mass.
Just because it is currently the only solution developed does not mean it is the one that nature chooses.
And that is why we need direct evidence of the Higgs; we need to produce an actual Higgs in the laboratory, study its properties, and verify our theoretical view of the world with cold, hard facts from experimental observation.
The 2011 LHC results
The LHC experiment is producing these facts and evidence.
If the Higgs is confirmed to exist, it would validate our theory of how particles acquire mass, and serve as the foundation for myriad experiments in the future. Many speculate this discovery would also warrant a Nobel Prize.
If the Higgs is confirmed to not exist, it would likely send many theorists back to the drawing board in hopes of finding that nature has an even more clever mechanism of how particles acquire mass than we have yet been capable of conceiving. And, just as the non-existence of the aether set the stage for relativity, the non-existence of the Higgs could set the stage for future surprises.
Either way it will be an exciting journey and the results from the LHC bring us one step closer to the answer.
Fredrick Olness is a theoretical physicist at SMU studying Quantum Chromodynamics (the fundamental force that binds nuclei) to help answer the questions: What are the fundamental building blocks of nature, and what holds them together?
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.
Higgs: Attempting to discover Standard Model’s missing piece
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.”
SMU researchers contributed to the results announced Tuesday by CERN
Besides Stroynowski, the SMU team of researchers includes three other Physics Department faculty: Jingbo Ye, Robert 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.
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.
“Professor Stroynowski has demonstrated extraordinary scientific leadership in keeping our relatively small Department of Physics at SMU engaged in one of the most significant scientific experiments of our time,” said Jim Quick, SMU Associate Vice President for Research.
SMU’s role in the LHC experiments provides SMU students a chance to participate in pioneering discoveries, said Olness.
“SMU students helped build the ATLAS detector, they were in the control room when the experiment started up, and they contributed to the analysis,” he said. “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.”
Higgs discovery would confirm decades-old theory
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 Robert 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.’”
Even if the LHC experiments find a particle where they expect to find the Higgs, it will take more analysis and more data to prove it is a Standard Model Higgs, according to CERN researchers. If scientists found subtle departures from the Standard Model in the particle’s behavior, this would point to the presence of new physics, linked to theories that go beyond the Standard Model. Observing a non-Standard Model Higgs, currently beyond the reach of the LHC experiments with the data they’ve recorded so far, would immediately open the door to new physics, said an official statement from CERN.
Results constrain Higgs’ mass to a range more limited than before
In announcing the findings, CERN noted that two experiments at the LHC have nearly eliminated the space in which the Higgs boson could dwell. The ATLAS and CMS experiments see modest excesses in their data that could soon uncover the famous missing piece of the physics puzzle, the scientists said.
The experiments’ main conclusion is that the Standard Model Higgs boson, if it exists, is most likely to have a mass constrained to the range 116-130 giga-electron-volts (GeV) by the ATLAS experiment, and 115-127 GeV by CMS. Tantalizing hints have been seen by both experiments in this mass region, but these are not yet strong enough to claim a discovery.
Both ATLAS and CMS have analyzed several decay channels, and the experiments see small excesses in the low mass region that has not yet been excluded.
Taken individually, none of these excesses is any more statistically significant than rolling a die and coming up with two sixes in a row. What is interesting is that there are multiple independent measurements pointing to the region of 124 to 126 GeV. It’s far too early to say whether ATLAS and CMS have discovered the Higgs boson, but these updated results are generating a lot of interest in the particle physics community.
The experiments revealed the latest results as part of their regular report to the CERN Council, which provides oversight for the laboratory near Geneva, Switzerland.
Experiments in coming months will refine the analysis
More than 1,600 scientists, students, engineers and technicians from more than 90 U.S. universities and five U.S. national laboratories take part in the ATLAS and CMS experiments. The Department of Energy’s Office of Science and the National Science Foundation provide support for U.S. participation in these experiments.
Over the coming months, both the ATLAS and CMS experiments will focus on refining their analyses in time for the winter particle physics conferences in March. The experiments will resume taking data in spring 2012.
Another possibility, discovering the absence of a Standard Model Higgs, would point to new physics at the LHC’s full design energy, set to be achieved after 2014. Whether ATLAS and CMS show over the coming months that the Standard Model Higgs boson exists or not, the LHC program is closing in on new discoveries. — CERN, Southern Methodist University
SMU is a member of the ATLAS experiment at the LHC. It takes a large team of scientists to search for the Higgs and other new physics; the SMU delegation includes faculty members Ryszard Stroynowski, Jingbo Ye, Robert Kehoe, Stephen Sekula, and a number of research professors, postdoctoral fellows and graduate students.
In addition, recent SMU ATLAS contributors include postdoctoral fellows Julia Hoffman, David Joffe (now at Kennesaw State), Ana Firan, Haleh Hadavand, Sami Kama, Aidan Randle-Conde and Peter Renkel, and graduate students Ryan Rios, Rozmin Daya, Renat Ishmukhametov Tingting Cao and Kamile Dindar-Yagci. Theoretical support was provided by faculty member Pavel Nadolsky, electronics development by research professors Andy Liu and Annie Xiang, and computer support by Justin Ross.