Tag: Annie C. Xiang

Physicists tune Large Hadron Collider to find “sweet spot” in high-energy proton smasher

Post author By Margaret Allen
Post date April 14, 2015

New launch of the world’s most powerful particle accelerator is the most stringent test yet of our accepted theories of how subatomic particles work and interact.

Start up of the world’s largest science experiment is underway — with protons traveling in opposite directions at almost the speed of light in the deep underground tunnel called the Large Hadron Collider near Geneva.

As protons collide, physicists will peer into the resulting particle showers for new discoveries about the universe, said Ryszard Stroynowski, a collaborator on one of the collider’s key experiments and a professor in the Department of Physics at Southern Methodist University, Dallas.

“The hoopla and enthusiastic articles generated by discovery of the Higgs boson two years ago left an impression among many people that we have succeeded, we are done, we understand everything,” said Stroynowski, who is the senior member of SMU’s Large Hadron Collider team. “The reality is far from this. The only thing that we have found is that Higgs exist and therefore the Higgs mechanism of generating the mass of fundamental particles is possible.”

There is much more to be learned during Run 2 of the world’s most powerful particle accelerator.

The Large Hadron Collider, the most powerful proton smasher in the world, includes the ATLAS detector, one of the LHC's four particle detectors. (CERN) — The Large Hadron Collider, the most powerful proton smasher in the world, includes the ATLAS detector, one of the LHC’s four particle detectors. (CERN)

“In a way we kicked a can down the road because we still do not have sufficient precision to know where to look for the really, really new physics that is suggested by astronomical observations,” he said. “The observed facts that are not explained by current theory are many.”

The LHC’s control room in Geneva on April 5 restarted the Large Hadron Collider. A project of CERN, the European Organization for Nuclear Research, the 17-mile LHC tunnel — big enough to ride a bicycle through — straddles the border between France and Switzerland.

Two years ago it made headlines worldwide when its global collaboration of thousands of scientists discovered the Higgs Boson fundamental particle.

The Large Hadron Collider’s first run began in 2009. In 2012 it was paused for an extensive upgrade.

The new upgraded and supercharged LHC restarts at almost twice the energy and higher intensity than it was operating at previously, so it will deliver much more data.

The Liquid Argon Calorimeter sits at the heart of the ATLAS detector — Data flowing from the ATLAS detector’s Liquid Argon Calorimeter — which measures the energies carried by particle interactions — is delivered via a data link computer chip developed by physicists at Southern Methodist University. (CERN)

“I think that in the LHC Run 2 we will sieve through more data than in all particle physics experiments in the world together for the past 50 years,” Stroynowski said. “Nature would be really strange if we do not find something new.”

SMU is active on the LHC’s ATLAS detector experiment
Within the big LHC tunnel, gigantic particle detectors at four interaction points along the ring record the proton collisions that are generated when the beams collide.

In routine operation, protons make 11,245 laps of the LHC per second — producing up to 1 billion collisions per second. With that many collisions, each detector captures collision events 40 million times each second.

That’s a lot of collision data, says SMU physicist Robert Kehoe, a member of the ATLAS particle detector experiment with Stroynowski and other SMU physicists.

Evaluating that much data isn’t humanly possible, so a computerized ATLAS hardware “trigger system” grabs the data, makes a fast evaluation, decides if it might hold something of interest to physicists, than quickly discards or saves it.

The Liquid Argon Calorimeter sits at the heart of ATLAS, measuring the energies carried by particle interactions. (CERN)

“That gets rid of 99.999 percent of the data,” Kehoe said. “This trigger hardware system makes measurements — but they are very crude, fast and primitive.”

To further pare down the data, a custom-designed software program culls even more data from each nano-second grab, reducing 40 million events down to 200.

Two groups from SMU, one led by Kehoe, helped develop software to monitor the performance of the trigger systems’ thousands of computer processors.

“The software program has to be accurate in deciding which 200 to keep. We must be very careful that it’s the right 200 — the 200 that might tell us more about the Higgs boson, for example. If it’s not the right 200, then we can’t achieve our scientific goals.”

The ATLAS computers are part of CERN’s computing center, which stores more than 30 petabytes of data from the LHC experiments every year, the equivalent of 1.2 million Blu-ray discs.

Flood of data from ATLAS transmitted via tiny electronics designed at SMU to withstand harsh conditions
An SMU physics team also collaborates on the design, construction and delivery of the ATLAS “readout” system — an electronic system within the ATLAS trigger system that sends collision data from ATLAS to its data processing farm.

Data from the ATLAS particle detector’s Liquid Argon Calorimeter is transmitted via 1,524 small fiber-optic transmitters. A powerful and reliable workhorse, the link is one of thousands of critical components on the LHC that contributed to discovery and precision measurement of the Higgs boson.

The custom-made high-speed data transmitters were designed to withstand extremely harsh conditions — low temperature and high radiation.

“It’s not always a smooth ride operating electronics in such a harsh environment,” said Jingbo Ye, the physics professor who leads the SMU data-link team. “Failure of any transmitter results in the loss of a chunk of valuable data. We’re working to improve the design for future detectors because by 2017 and 2018, the existing optical data-link design won’t be able to carry all the data.”

Each electrical-to-optical and optical-to-electrical signal converter transmits 1.6 gigabytes of data per second. Lighter and smaller than their widely used commercial counterpart, the tiny, wickedly fast transmitters have been transmitting from the Liquid Argon Calorimeter for about 10 years.

Upgraded optical data link is now in the works to accommodate beefed-up data flow
A more powerful data link — much smaller and faster than the current one — is in research and development now. Slated for installation in 2017, it has the capacity to deliver 5.2 gigabytes of data per second.

The new link’s design has been even more challenging than the first, Ye said. It has a smaller footprint than the first, but handles more data, while at the same time maintaining the existing power supply and heat exchanger now in the ATLAS detector.

The link will have the highest data density in the world of any data link based on the transmitter optical subassembly TOSA, a standard industrial package, Ye said.

Fine-tuning the new, upgraded machine will take several weeks
The world’s most powerful machine for smashing protons together will require some “tuning” before physicists from around the world are ready to take data, said Stephen Sekula, a researcher on ATLAS and assistant professor of physics at SMU.

The trick is to get reliable, stable beams that can remain in collision state for 8 to 12 to 24 hours at a time, so that the particle physicists working on the experiments, who prize stability, will be satisfied with the quality of the beam conditions being delivered to them, Sekula said.

“The LHC isn’t a toaster,” he said. “We’re not stamping thousands of them out of a factory every day, there’s only one of them on the planet and when you upgrade it it’s a new piece of equipment with new idiosyncrasies, so there’s no guarantee it will behave as it did before.”

Machine physicists at CERN must learn the nuances of the upgraded machine, he said. The beam must be stable, so physicists on shifts in the control room can take high-quality data under stable operating conditions.

The process will take weeks, Sekula said.

10 times as many Higgs particles means a flood of data to sift for gems
LHC Run 2 will collide particles at a staggering 13 teraelectronvolts (TeV), which is 60 percent higher than any accelerator has achieved before.

“On paper, Run 2 will give us four times more data than we took on Run 1,” Sekula said. “But each of those multiples of data are actually worth more. Because not only are we going to take more collisions, we’re going to do it at a higher energy. When you do more collisions and you do them at a higher energy, the rate at which you make Higgs Bosons goes way up. We’re going to get 10 times more Higgs than we did in run 1 — at least.”

SMU’s ManeFrame supercomputer plays a key role in helping physicists from the Large Hadron Collider experiments. One of the fastest academic supercomputers in the nation, it allows physicists at SMU and around the world to sift through the flood of data, quickly analyze massive amounts of information, and deliver results to the collaborating scientists.

During Run 1, the LHC delivered about 8,500 Higgs particles a week to the scientists, but also delivered a huge number of other kinds of particles that have to be sifted away to find the Higgs particles. Run 2 will make 10 times that, Sekula said. “So they’ll rain from the sky. And with more Higgs, we’ll have an easier time sifting the gems out of the gravel.”

Run 2 will operate at the energy originally intended for Run 1, which was initially stalled by a faulty electrical connection on some superconducting magnets in a sector of the tunnel. Machine physicists were able to get the machine running — just never at full power. And still the Higgs was discovered, notes SMU physics professor Fredrick Olness.

“The 2008 magnet accident at the LHC underscores just how complex a machine this is,” Olness said. “We are pushing the technology to the cutting-edge.”

Huge possibilities for new discoveries, but some will be more important than others
There are a handful of major new discoveries that could emerge from Run 2 data, Stroynowski said.

New physics laws related to Higgs — Physicists know only global Higgs properties, many with very poor understanding. They will be measuring Higgs properties with much greater precision, and any deviation from the present picture will indicate new physics laws. “Improved precision is the only guaranteed outcome of the coming run,” Stroynowski said. “But of course we hope that not everything will be as expected. Any deviation may be due to supersymmetry or something completely new.”
Why basic particles have such a huge range of masses — Clarity achieved by precision measurements of Higgs properties may help to shed light on the exact reason for the pattern of masses found in the known fundamental particles. If new particles are discovered in the LHC during Run 2, the mathematical theories that could explain them might also shed light on the puzzle of why masses have such diversity in the building blocks of nature
Dark matter — Astronomical observations require a new form of matter that acts only via gravity, otherwise all galaxies would have fallen apart a long time ago. One candidate theory is supersymmetry, which predicts a host of new particles. Some of those particles, if they exist, would fit the characteristics of dark matter. LHC scientists will be looking for them in the coming run both directly, and for indirect effects.
Quark gluon plasma — In collisions of lead nuclei with each other, LHC scientists have observed a new form of matter called quark gluon plasma. Thought to have been present in the cosmos near the very beginning of time, making and studying this state of matter could teach us more about the early, hot, dense universe.
Mini black-holes — Some scientists are looking for “mini black-holes” predicted by innovative physicist Stephen Hawking, but that is considered “a v-e-e-e-e-r-y long shot,” Stroynowski said.
Matter-antimatter — A cosmic imbalance in the amounts of matter and its opposite, antimatter, must be explained by particle physics. The LHC is home to several experiments and teams that aim to search for answers.

— SMU, Fermilab, CERN

Tags Andrew Turvey, Annie C. Xiang, Ashleigh Miller, Dedman College, Fredrick Olness, Jingbo Ye, Matthew Stein, Robert Kehoe, Ryszard Stroynowski, Sami Kama, SMU Department of Physics, Stephen J. Sekula

Energy & Matter Researcher news

SMU physicists celebrate Nobel Prize for discovery of Higgs boson “god particle”

Post author By Margaret Allen
Post date October 8, 2013

SMU joins nearly 2,000 physicists from U.S. institutions — including 89 U.S. universities and seven U.S. DOE labs — that participate in discovery experiments

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.

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For more information, www.smuresearch.com.

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.

Tags Annie C. Xiang, Dedman College, Fredrick Olness, Jingbo Ye, Julia Hoffman, Pavel Nadolsky, Robert Kehoe, Ryan Rios, Ryszard Stroynowski, SMU Department of Physics, Stephen J. Sekula

Energy & Matter Researcher news Technology

Fiber-optic data link, now with DOE funding, is critical in the hunt for Big Bang’s “God” particle

Post author By Margaret Allen
Post date June 29, 2012

Tiny optoelectronic module plays a key role in the world’s largest physics experiments; new module will be 75 times faster than the current fiber-optic data link on Large Hadron Collider’s ATLAS experiment

1st gen link,pink,400x300 — The SMU fiber-optic data link (above) was made specifically for ATLAS and its extremely harsh low-temperature, high-radiation environment. More than 1,500 of the data link modules are installed on ATLAS. A second-generation link, which is five times faster but with a smaller footprint, is slated for the next upgrade of the LHC detectors. A planned third-generation data link, being funded by DOE, will be 75 times faster.(Credit: www.smuresearch.com)

A tiny optoelectronic module designed in part by SMU physicists plays a big role in the world’s largest physics experiment at CERN in Switzerland, where scientists are searching for the “God” particle.

The module, a fiber-optic transmitter, sends the Large Hadron Collider’s critical raw data from its ATLAS experiment to offsite computer farms. From there, thousands of physicists around the world access the data and analyze it for the long-sought-after particle, the Higgs boson.

Now as a result of SMU’s role on the LHC data link, SMU Physics Research Professor Annie Xiang has won a three-year research and development grant with $67,500 in support annually from the U.S. Department of Energy to advance the design of the optoelectronic module.

The grant calls for a customized multi-channel optical transmitter that can be deployed on many of the world’s high-energy particle detectors.

Xiang is principal investigator for SMU’s Data Links Group in SMU’s Physics Department, working in the Optoelectronics Lab of Physics Professor Jingbo Ye. She coordinates the lab’s development of optical data transmission systems for particle physics experiments.

More than 1,500 data link modules are installed on ATLAS
“We made the first-generation fiber-optic data link specifically for ATLAS and its extremely harsh low-temperature, high-radiation environment,” Xiang said.

More than 1,500 of the first-generation data link modules are installed on the calorimeter detectors of ATLAS. The link’s job is to reliably offload a continuous flood of raw data without failure or error. Scientists scour the data for signs of the Higgs boson, which has been theorized for decades but never actually observed. It is believed the Higgs gives mass to the matter that we observe.

A second-generation data link, which SMU also helped design, is slated for deployment in the next upgrade of the LHC in coming years. The current data link installed in ATLAS can transmit up to 1.6 gigabits a second in a single channel, which equates to writing an HD DVD in one minute, Xiang said. The second-generation link, a 5 gigabit transceiver, has a smaller footprint than the current link, but can transmit three times faster and is qualified for even higher radiation. “Many thousands of the second-generation link can be expected across the LHC detectors,” Xiang said.

The data link being supported by DOE will be even faster. A transmitter only, it will have a transmission capacity of 120 gigabits a second, or 75 times faster than the data link currently installed on ATLAS, Xiang said.

DOE project will customize off-the-shelf commercial components for on-detector installation
To design the links, SMU’s team and its collaborators start with qualified commercial transmitters and receivers, then customize them for the LHC detectors, Xiang said. They will repeat that process to develop the data link being supported by DOE.

Called a “generic” module, the link supported by DOE isn’t specified for any particular detector, but rather will be available to deploy on detectors at the LHC, at Fermi National Accelerator Laboratory (Fermilab) and others.

The module — a 12-channel transmitter — must be high speed and low footprint, and able to withstand an extremely cold and high-radiation environment, while at the same time maintaining low mass and low power consumption, Xiang said.

The DOE award is part of a collaborative project with Fermilab, the University of Minnesota, The Ohio State University and Argonne National Laboratory, with a total funding of $900,000. SMU designed the first-generation module in collaboration with Taiwan’s Academia Sinica. SMU collaborated on the second-generation module with CERN, Oxford University and Fermilab.

Ye and Xiang are members of SMU’s ATLAS team, which is led by SMU Physics Professor Ryszard Stroynowski. — Margaret Allen

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.

Tags Annie C. Xiang, Dedman College, Jingbo Ye, Ryszard Stroynowski, SMU Department of Physics

Energy & Matter Researcher news Student researchers Technology

SMU physicists at CERN find hints of long sought after Higgs boson — dubbed the fundamental “God” particle

Post author By Margaret Allen
Post date December 13, 2011

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.

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

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.

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.

“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.

Tags Annie C. Xiang, Dedman College, Fredrick Olness, Jingbo Ye, Julia Hoffman, Pavel Nadolsky, Robert Kehoe, Ryan Rios, Ryszard Stroynowski, SMU Department of Physics, Stephen J. Sekula