Tevatron scientists announce their final results on the Higgs particle

After more than 10 years of gathering and analyzing data produced by the U.S. Department of Energy’s Tevatron collider, scientists from the CDF and DZero collaborations have found their strongest indication to date for the long-sought Higgs particle. Squeezing the last bit of information out of 500 trillion collisions produced by the Tevatron for each experiment since March 2001, the final analysis of the data does not settle the question of whether the Higgs particle exists, but gets closer to an answer. The Tevatron scientists unveiled their latest results on July 2, two days before the highly anticipated announcement of the latest Higgs-search results from the Large Hadron Collider in Europe.

“The Tevatron experiments accomplished the goals that we had set with this data sample,” said Fermilab’s Rob Roser, cospokesperson for the CDF experiment at DOE’s Fermi National Accelerator Laboratory. “Our data strongly point toward the existence of the Higgs boson, but it will take results from the experiments at the Large Hadron Collider in Europe to establish a discovery.”

Scientists of the CDF and DZero collider experiments at the Tevatron received a round of rousing applause from hundreds of colleagues when they presented their results at a scientific seminar at Fermilab. The Large Hadron Collider results will be announced at a scientific seminar at 2 a.m. CDT on July 4 at the CERN particle physics laboratory in Geneva, Switzerland.

“It is a real cliffhanger,” said DZero co-spokesperson Gregorio Bernardi, physicist at the Laboratory of Nuclear and High Energy Physics, or LPNHE, at the University of Paris VI & VII. “We know exactly what signal we are looking for in our data, and we see strong indications of the production and decay of Higgs bosons in a crucial decay mode with a pair of bottom quarks, which is difficult to observe at the LHC. We are very excited about it.”

The Higgs particle is named after Scottish physicist Peter Higgs, who among other physicists in the 1960s helped develop the theoretical model that explains why some particles have mass and others don’t, a major step toward understanding the origin of mass. The model predicts the existence of a new particle, which has eluded experimental detection ever since. Only high-energy particle colliders such as the Tevatron, which was shut down in September 2011, and the Large Hadron Collider, which produced its first collisions in November 2009, have the chance to produce the Higgs particle. About 1,700 scientists from U.S. institutions, including Fermilab, are working on the LHC experiments.

The Tevatron results indicate that the Higgs particle, if it exists, has a mass between 115 and 135 GeV/c², or about 130 times the mass of the proton.

“During its life, the Tevatron must have produced thousands of Higgs particles, if they actually exist, and it’s up to us to try to find them in the data we have collected,” said Luciano Ristori, co-spokesperson of the CDF experiment and physicist at Fermilab and the Italian Istituto Nazionale di Fisica Nucleare (INFN) . “We have developed sophisticated simulation and analysis programs to identify Higgs-like patterns. Still, it is easier to look for a friend’s face in a sports stadium filled with 100,000 people than to search for a Higgs-like event among trillions of collisions.”

The final Tevatron results corroborate the Higgs search results that scientists from the Tevatron and the LHC presented at physics conferences in March 2012.

The search for the Higgs particle at the Tevatron focuses on a different decay mode than the search at the LHC. According to the theoretical framework known as the Standard Model of Particles, Higgs bosons 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. At the LHC, the experiments can most easily observe the existence of a Higgs particle by searching for its decay into two energetic photons. At the Tevatron, experiments most easily see the decay of a Higgs particle into a pair of bottom quarks.

Tevatron scientists found that the observed Higgs signal in the combined CDF and DZero data in the bottom-quark decay mode has a statistical significance of 2.9 sigma. This means there is only a 1-in-550 chance that the signal is due to a statistical fluctuation.

“We achieved a critical step in the search for the Higgs boson,” said Dmitri Denisov, DZero cospokesperson and physicist at Fermilab. “While 5-sigma significance is required for a discovery, it seems unlikely that the Tevatron collisions mimicked a Higgs signal. Nobody expected the Tevatron to get this far when it was built in the 1980s.”

The Tevatron is one of eight particle accelerators and storage rings on the Fermilab site. The largest, operational accelerator at Fermilab now is the 2-mile-circumference Main Injector, which provides particles for the laboratory’s neutrino and muon research programs.

The CDF and DZero collaborations submitted their joint Higgs search results to the electronic preprint archive arXiv.org. The paper also is available at:
http://tevnphwg.fnal.gov/results/SM_Higgs_Summer_12/

Read frequently asked questions about the Higgs boson.

: After more than 10 years of gathering and analyzing data produced by the U.S. Department of Energy’s Tevatron collider, scientists from the CDF and DZero experiments have found their strongest indication to date for the long-sought Higgs particle. The Tevatron results indicate that the Higgs particle, if it exists, has a mass between 115 and 135 GeV/c², or about 130 times the mass of the proton.

: The 4-mile-in-circumference Tevatron accelerator, shut down in September 2011, is one of eight particle accelerators and storage rings at the Department of Energy’s Fermilab. It used superconducting magnets to propel protons and antiprotons to nearly the speed of light. In the foreground is the 2-mile Main Injector accelerator, which powers Fermilab’s neutrino and muon research programs.

: The Tevatron typically produced about 10 million proton-antiproton collisions per second. Each collision produced hundreds of particles. The CDF and DZero experiments recorded about 200 collisions per second for further analysis.

: The three-story, 6,000-ton CDF detector recorded snapshots of the particles that emerge when protons and antiprotons collide.

: Scientists measured the energy, momentum and electric charges of subatomic particles using a three-story assembly of sub detectors wrapped around DZero’s collision area like the layers of an onion.

Fermilab scientist Don Lincoln describes the concept of how the search for the Higgs boson is accomplished.

Notes to the editors:

CDF is an international experiment of 430 physicists from 58 institutions in 15 countries . DZero is an international experiment conducted by 446 physicists from 82 institutions in 18 countries. Funding for the CDF and DZero experiments comes from DOE’s Office of Science, the National Science Foundation, and a number of international funding agencies.

CDF collaborating institutions are at http://www-cdf.fnal.gov/collaboration/index.html

DZero collaborating institutions are at http://www-d0.fnal.gov/ib/Institutions.html

Fermilab is America’s premier national laboratory for particle physics research. A U.S. Department of Energy Office of Science laboratory, Fermilab is located near Chicago, Illinois and operated under contract by the Fermi Research Alliance, LLC. Visit Fermilab’s website at http://www.fnal.gov and follow us on Twitter at @FermilabToday.

The DOE Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit http://science.energy.gov.

Credit: Fermilab

Our galaxy, the Milky Way, is a large spiral galaxy surrounded by dozens of smaller satellite galaxies. Scientists have long theorized that occasionally these satellites will pass through the disk of the Milky Way, perturbing both the satellite and the disk. A team of astronomers from Canada and the United States have discovered what may well be the smoking gun of such an encounter, one that occurred close to our position in the galaxy and relatively recently, at least in the cosmological sense.

“We have found evidence that our Milky Way had an encounter with a small galaxy or massive dark matter structure perhaps as recently as 100 million years ago,” said Larry Widrow, professor at Queen’s University in Canada. “We clearly observe unexpected differences in the Milky Way’s stellar distribution above and below the Galaxy’s midplane that have the appearance of a vertical wave — something that nobody has seen before.”

The discovery is based on observations of some 300,000 nearby Milky Way stars by the Sloan Digital Sky Survey. Stars in the disk of the Milky Way move up and down at a speed of about 20-30 kilometers per second while orbiting the center of the galaxy at a brisk 220 kilometers per second. Widrow and his four collaborators from the University of Kentucky, the University of Chicago and Fermi National Accelerator Laboratory have found that the positions and motions of these nearby stars weren’t quite as regular as previously thought.

“Our part of the Milky Way is ringing like a bell,” said Brian Yanny, of the Department of Energy’s Fermilab. “But we have not been able to identify the celestial object that passed through the Milky Way. It could have been one of the small satellite galaxies that move around the center of our galaxy, or an invisible structure such as a dark matter halo.”

Adds Susan Gardner, professor of physics at the University of Kentucky: “The perturbation need not have been a single isolated event in the past, and it may even be ongoing. Additional observations may well clarify its origin.”

When the collaboration started analyzing the SDSS data on the Milky Way, they noticed a small but statistically significant difference in the distribution of stars north and south of the Milky Way’s midplane. For more than a year, the team members explored various explanations of this north-south asymmetry, such as the effect of interstellar dust on distance determinations and the way the stars surveyed were selected. When those attempts failed, they began to explore the alternative explanation that the data was telling them something about recent events in the history of the Galaxy.

The scientists used computer simulations to explore what would happen if a satellite galaxy or dark matter structure passed through the disk of the Milky Way. The simulations indicate that over the next 100 million years or so, our galaxy will “stop ringing:” the north-south asymmetry will disappear and the vertical motions of stars in the solar neighborhood will revert back to their equilibrium orbits — unless we get hit again.

The Milky Way is more than 9 billion years old with about 100 billion stars and total mass more than 300 billion times that of the sun. Most of the mass in and around the Milky Way is in the form of dark matter.

Scientists know of more than 20 visible satellite galaxies that circle the center of the Milky Way, with masses ranging from one million to one billion solar masses. There may also be invisible satellites made of dark matter. (There is six times as much dark matter in the universe as ordinary, visible matter.) Astronomers’ computer simulations have found that this invisible matter formed hundreds of massive structures that move around our Milky Way.

Because of their abundance, these dark matter satellites are more likely than the visible satellite galaxies to cut through the Milky Way’s midplane and cause vertical waves.

“Future astronomical programs, such as the space-based Gaia Mission, will be able to map out the vertical perturbations in our galaxy in unprecedented detail,” Widrow said. “That will offer a strong test of our findings.”

The results have been published in The Astrophysical Journal Letters:
http://iopscience.iop.org/2041-8205/750/2/L41/pdf/2041-8205_750_2_L41.pdf

Every day researchers add another sea of data to an ocean of knowledge on the world around us — billions on top of billions of measurements, images and observations of the tiniest subatomic particles up to the movement of planets and stars.

“Making sense of that — simulating, mapping, analyzing — this is how researchers work these days,” said Miron Livny, computer sciences professor at the University of Wisconsin–Madison. “More and more researchers need more and more computing power to support that work.”

To that end, the Department of Energy Office of Science and the National Science Foundation have committed up to $27 million to Open Science Grid (OSG), a nine-member partnership extending the reach of distributed high-throughput computing (DHTC) capabilities.

Distributed computing musters the power of a network of machines that reside at different institutions to make the best use of all available processing and storage capacity, giving scientists the muscle of a supercomputer that may otherwise be out of reach.

Expanded over the last six years to include more than 80 sites contributing users and data storage and processing capacity, OSG now delivers more than 2 million computing hours and moves about a third of a petabyte of data on a daily basis.

“The commitment from the two agencies will take the capabilities and culture we’ve developed to more campuses throughout the United States,” said Livny, OSG’s principal investigator. “It is about advancing the state of the art to support education and research in more science domains and improve our ability to handle more data.”

The OSG Consortium bridges organizational boundaries, working directly with faculty, students and system administrators at campuses across the nation, as well as large multi-national scientific collaborations such as the Large Hadron Collider at the European Center for Nuclear Research.

“Our close partnerships allow us to build on existing experience in working with and processing Big Data and the advanced networks needed to transport the massive datasets of the future,” said Michael Ernst, an OSG co-principal investigator who directs the Brookhaven National Laboratory RHIC/ATLAS Computing Facility and coordinates computing activities across the United States for ATLAS, one of the LHC’s largest particle physics experiments.

“Moving forward, the OSG will continue to bring these principles and technologies to the benefit of new research communities, and also expand its services, integrating networks, data and ever more complex user workflows,” said Lothar Bauerdick, OSG executive director and head of the U.S. LHC Compact Muon Solenoid experiment software and computing project.

OSG, a full partner in the NSF Extreme Digital program and a member of the XSEDE federation, will field new tools for distributed computing to facilitate sharing of computational resources both on and between campuses.

“The OSG has been developing the Virtual Data Toolkit for over 10 years,” said Frank Würthwein, an OSG co-principal investigator and physics professor at the University of California–San Diego. “This software service acts as an anchor for the DHTC community, supporting components that researchers need but are no longer supported elsewhere. Over the next five years, the OSG software services will expand into new, more community-specific, integrated software solutions via the VDT.”

The DOE Office of Science portion of the funding—up to $8.2 million — will support distributed computing efforts based at DOE national laboratories that make masses of data from experiments at the LHC available to U.S. researchers at their home institutions. The balance of the funding, contributed by NSF, will be used to promote distributed computing resources at U.S. universities.

Under the new award, nine institutions will receive funding: Brookhaven National Laboratory, Fermi National Accelerator Laboratory, University of Chicago, University of Wisconsin Madison, Indiana University, University of California San Diego, University of Illinois at Urbana-Champaign, University of Nebraska, and the Information Sciences Institute at the University of Southern California.

“The members of the OSG Consortium are fully committed to collaborating over the next five years to make this project a success,” said Ruth Pordes, chair of the OSG Council and the Fermilab Computing Sector associate head for Grids. “By working together, the OSG project and the scientists who use the OSG will be able to achieve great things.”

Batavia, Illinois—Fermi National Accelerator Laboratory welcomes the public to view its herd of American bison, commonly known as buffalo. Five calves have been born in the past few weeks, increasing the herd size to 25. Visitors, including families with young children, can enter the Fermilab site through its Pine Street entrance in Batavia or the Batavia Road entrance in Warrenville. Admission is free, but a valid photo ID is necessary to enter the site. Summer hours are from 8 a.m. to 8 p.m., seven days a week.

Fermilab’s first director, Robert Wilson, established the bison herd in 1969 as a symbol of the history of the Midwestern prairie and the laboratory’s pioneering research at the frontiers of particle physics. The herd remains a major attraction for families and wildlife enthusiasts. Today, the Fermilab site also boasts 1,100 acres of reconstructed tall-grass prairie as well as seven particle accelerators. The U.S. Department of Energy designated the 6,800-acre Fermilab site a National Environmental Research Park in 1989.

Visitors can learn more about nature at Fermilab by hiking the Interpretive Prairie Trail, a half-mile-long trail located near the Pine Street entrance. The Leon Lederman Science Education Center offers exhibits on the prairie and hands-on physics displays. The Lederman Center hours are Monday-Friday from 8:30 a.m. to 4:30 p.m. and Saturdays from 9 a.m. to 3 p.m.

For up-to-date information for visitors, please visit www.fnal.gov or call (630) 840-3351.

To learn more about Fermilab’s bison herd, please visit our website at www.fnal.gov/pub/about/campus/ecology/wildlife/bison.html.

: Fermilab welcomes the public to view its herd of American bison, commonly known as buffalo. The herd grazes on a pasture half a mile from Wilson Hall, Fermilab’s 16-story administrative building. Photo: Fermilab

: Fermilab’s first director, Robert Wilson, established the bison herd in 1969 as a symbol of the history of the Midwestern prairie and the laboratory’s pioneering research at the frontiers of particle physics. Photo: Fermilab

: North American bison can reach a height of more than five feet and a weight of 2,500 pounds. They can run at a speed of more than 30 miles an hour. Photo: Fermilab

: Buffalo babies are usually born in spring, after a gestation of nine months. Photo: Fermilab

Batavia, Illinois—Scientists from the MINOS experiment at the Department of Energy’s Fermi National Accelerator Laboratory have revealed the world’s most precise measurement of a key parameter that governs the transformation of one type of neutrino to another. The results confirm that neutrinos and their antimatter counterparts, antineutrinos, have similar masses as predicted by most commonly accepted theories that explain how the subatomic world works.

MINOS caused a jolt in the physics world in 2010 when it announced that a measurement of this parameter, called delta m squared, showed a surprisingly large difference between the masses of neutrinos and antineutrinos. A subsequent 2011 measurement with increased statistics appeared to bring the neutrino and antineutrino masses closer in sync. With twice as much antineutrino data collected since its 2011 result, scientists confirm that the gap has closed. This upholds predictions and provides crucial information for many other neutrino experiments around the globe.

The new measurement is one of several announced this week by the MINOS experiment at the Neutrino 2012 conference in Kyoto, Japan. These are the final results from the first phase of the MINOS experiment.

“At the end of its initial seven-year run, MINOS has proven that it has been an incredibly successful long-baseline neutrino experiment,” said Fermilab’s Rob Plunkett, MINOS co-spokesperson. “We look forward to the next phase, when we will search for a new type of neutrino.”

MINOS scientists also announced this week their latest measurement of the search for a rare phenomenon, the transformation of muon neutrinos into electron neutrinos. The Daya Bay experiment in China and the RENO experiment in Korea made headlines earlier this year with their measurements of this transformation, observed in neutrinos generated by nuclear reactors.

To measure the transformation of one type of neutrino to another, the MINOS experiment sends a beam of muon neutrinos 450 miles (735 kilometers) through the earth from the Main Injector accelerator at Fermilab to a 5,000-ton neutrino detector located half a mile underground in the Soudan Underground Laboratory in northern Minnesota. The experiment uses two almost identical detectors: the detector at Fermilab is used to check the purity of the muon neutrino beam, and the detector at Soudan looks for electron and muon neutrinos. The neutrinos’ trip from Fermilab to Soudan takes about 2.5 milliseconds, giving the neutrinos enough time to change their identities.

With its full data set collected, MINOS recorded a total of 21 electron-neutrino-like events on top of a background of 79. This represents 40% more data than its 2011 measurement of this transformation. The larger data set allowed MINOS scientists to improve their measurement of a parameter that describes this transformation, called sin²2θ₁₃. The new measurement remains consistent with the experiment’s previous measurements and provides an important clue to understanding the puzzle of neutrinos – how they transform from one type to another, and which of the three neutrino types is the most massive.

Because MINOS uses different types of neutrinos than those produced by nuclear reactors, and compared to the Japanese experiment T2K has its two detectors significantly farther apart, its measurements of the transformation of muon to electron neutrinos are sensitive to different effects than other worldwide experiments. In particular, depending on how nature has chosen to order the neutrino masses, MINOS measurements of the parameter sin²2θ₁₃ could be different from those made by T2K.

“The results from MINOS have pushed the endeavor into the next phase: now we start to look for the mass ordering of neutrinos,” said University College London Professor Jenny Thomas, co-spokesperson for the MINOS experiment. “Fermilab will lead this endeavor with its NOvA experiment that will start next year.”

In 2013 the upgraded Fermilab accelerator complex will send an even more intense and higher-energy beam of muon neutrinos to two experiments in Northern Minnesota: the brand-new NOvA experiment and the second phase of MINOS. In its next phase, MINOS will focus on the hunt for a fourth type of neutrino. Hints of a fourth type have been observed in two previous experiments.

The MINOS experiment involves more than 140 scientists, engineers, technical specialists and students from 30 institutions, including universities and national laboratories, in five countries: Brazil, Greece, Poland, the United Kingdom and the United States. Funding comes from: the U.S. Department of Energy’s Office of Science; the U.K.’s Science and Technology Facilities Council; the U.S. National Science Foundation; the University of Minnesota, which operates the Soudan Underground Laboratory; Brazil’s Foundation for Research Support of the State of São Paulo (FAPESP) and National Council of Scientific and Technological Development (CNPq) and the University of Athens in Greece.

: This graph shows the parameters for muon neutrino mixing. The blue curve shows the latest MINOS result for the boundary of the region of allowed values for the mixing parameters. The MINOS result is compared with measurements from other experiments (red, gray, green).The blue star is the set of parameters preferred by the MINOS data, specifically a delta m squared of 2.39×10^-3 ev² and a value for sin² (2theta) of 0.96. The new MINOS result uses all neutrino beam and antineutrino beam data from the NuMI beamline and also includes data from atmospheric neutrinos collected at the MINOS detector.

: The blue and red regions in both plots show the areas allowed by MINOS for the parameters of electron-neutrino appearance. The top plot shows the MINOS measurement for one ordering of neutrino masses; the bottom plot shows the same measurement assuming the other mass ordering. The vertical axis shows allowed values of an unknown parameter that controls how much neutrinos and antineutrinos show different behavior in this process.

: Scientists know that there exist three types of neutrinos and three types of antineutrinos. Cosmological observations and laboratory-based experiments indicate that the masses of these particles must be extremely small: Each neutrino and antineutrino must weigh less than a millionth of the weight of an electron.

: Neutrinos, ghost-like particles that rarely interact with matter, travel 450 miles straight through the earth from Fermilab to Soudan — no tunnel needed. The Main Injector Neutrino Oscillation Search (MINOS) experiment studies the neutrino beam using two detectors. The MINOS near detector, located at Fermilab, records the composition of the neutrino beam as it leaves the Fermilab site. The MINOS far detector, located in Minnesota, half a mile underground, again analyzes the neutrino beam. This allows scientists to directly study the oscillation of muon neutrinos into electron neutrinos or tau neutrinos under laboratory conditions.

: The MINOS far detector is located in a cavern half a mile underground in the Soudan Underground Laboratory, Minnesota. The 100-foot-long MINOS far detector consists of 486 massive octagonal planes, lined up like the slices of a loaf of bread. Each plane consists of a sheet of steel about 25 feet high and one inch thick, with the last one visible in the photo. The whole detector weighs 6,000 tons. Since March 2005, the far detector has recorded neutrinos from a beam produced at Fermilab. The MINOS collaboration records about 1,000 neutrinos per year.

: The 1,000-ton MINOS near detector sits 350 feet underground at Fermilab. The detector consists of 282 octagonal-shaped detector planes, each weighing more than a pickup truck. Scientists use the near detector to verify the intensity and purity of the muon neutrino beam leaving the Fermilab site. Photo: Peter Ginter

: Fermilab completed the construction and testing of the Neutrino at the Main Injector (NuMI) beam line in early 2005. Protons from Fermilab’s Main Injector accelerator (left) travel 1,000 feet down the beam line, smash into a graphite target and create muon neutrinos. The neutrinos traverse the MINOS near detector, located at the far end of the NuMI complex, and travel straight through the earth to a former iron mine in Soudan, Minnesota, where they cross the MINOS far detector. Some of the neutrinos arrive as electron neutrinos or tau neutrinos.

: When operating at highest intensity, the NuMI beam line transports a package of 35,000 billion protons every two seconds to a graphite target. The target converts the protons into bursts of particles with exotic names such as kaons and pions. Like a beam of light emerging from a flashlight, the particles form a wide cone when leaving the target. A set of two special lenses, called horns (photo), is the key instrument to focus the beam and send it in the right direction. The beam particles decay and produce muon neutrinos, which travel in the same direction. Photo: Peter Ginter

: More than 140 scientists, engineers, technical specialists and students from Brazil, Greece, Poland, the United Kingdom and the United States are involved in the MINOS experiment. This photo shows some of them posing for a group photo at Fermilab, with the 16-story Wilson Hall and the spiral-shaped MINOS service building in the background.

: Far view The University of Minnesota Foundation commissioned a mural for the MINOS cavern at the Soudan Underground Laboratory, painted onto the rock wall, 59 feet wide by 25 feet high. The mural contains images of scientists such as Enrico Fermi and Wolfgang Pauli, Wilson Hall at Fermilab, George Shultz, a key figure in the history of Minnesota mining, and some surprises. A description of the mural, painted by Minneapolis artist Joe Giannetti, is available here.

Using different search techniques, Tevatron physicists see hints of Higgs boson sighting consistent with those from LHC

Batavia, Ill. — New measurements announced today by scientists from the CDF and DZero collaborations at the Department of Energy’s Fermi National Accelerator Laboratory indicate that the elusive Higgs boson may nearly be cornered. After analyzing the full data set from the Tevatron accelerator, which completed its last run in September 2011, the two independent experiments see hints of a Higgs boson.

Physicists from the CDF and DZero collaborations found excesses in their data that might be interpreted as coming from a Higgs boson with a mass in the region of 115 to 135 GeV. In this range, the new result has a probability of being due to a statistical fluctuation at level of significance known among scientists as 2.2 sigma. This new result also excludes the possibility of the Higgs having a mass in the range from 147 to 179 GeV.

Physicists claim evidence of a new particle only if the probability that the data could be due to a statistical fluctuation is less than 1 in 740, or three sigmas. A discovery is claimed only if that probability is less than 1 in 3.5 million, or five sigmas.

This result sits well within the stringent constraints established by earlier direct and indirect measurements made by CERN’s Large Hadron Collider, the Tevatron, and other accelerators, which place the mass of the Higgs boson within the range of 115 to 127 GeV. These findings are also consistent with the December 2011 announcement of excesses seen in that range by LHC experiments, which searched for the Higgs in different decay patterns. None of the hints announced so far from the Tevatron or LHC experiments, however, are strong enough to claim evidence for the Higgs boson.

“The end game is approaching in the hunt for the Higgs boson,” said Jim Siegrist, DOE Associate Director of Science for High Energy Physics. “This is an important milestone for the Tevatron experiments, and demonstrates the continuing importance of independent measurements in the quest to understand the building blocks of nature.”

Physicists from the CDF and DZero experiments made the announcement at the annual conference on Electroweak Interactions and Unified Theories known as Rencontres de Moriond in Italy. This is the latest result in a decade-long search by teams of physicists at the Tevatron.

“I am thrilled with the pace of progress in the hunt for the Higgs boson. CDF and DZero scientists from around the world have pulled out all the stops to reach this very nice and important contribution to the Higgs boson search,” said Fermilab Director Pier Oddone. “The two collaborations independently combed through hundreds of trillions of proton-antiproton collisions recorded by their experiments to arrive at this exciting result.”

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. Discovering the Higgs boson relies on observing a statistically significant excess of the particles into which the Higgs decays and those particles must have corresponding kinematic properties that allow for the mass of the Higgs to be reconstructed.

“There is still much work ahead before the scientific community can say for sure whether the Higgs boson exists,” said Dmitri Denisov, DZero co-spokesperson and physicist at Fermilab. “Based on these exciting hints, we are working as quickly as possible to further improve our analysis methods and squeeze the last ounce out of Tevatron data.”

Only high-energy particle colliders such as the Tevatron and LHC can recreate the energy conditions found in the universe shortly after the Big Bang. According to the Standard Model, the theory that explains and predicts how nature’s building blocks behave and interact with each other, the Higgs boson gives mass to other particles.

“Without something like the Higgs boson giving fundamental particles mass, the whole world around us would be very different from what we see today,” said Giovanni Punzi, CDF co-spokesperson and physicist at the National Institute of Nuclear Physics, or INFN, in Pisa, Italy. “Physicists have known for a long time that the Higgs or something like it must exist, and we are eager to finally pin this phenomenon down and start learning more about it.”

If a Higgs boson is created in a high-energy particle collision, it immediately decays into lighter more stable particles before even the world’s best detectors and fastest computers can snap a picture of it. To find the Higgs boson, physicists retraced the path of these secondary particles and ruled out processes that mimic its signal.

The experiments at the Tevatron and the LHC offer a complementary search strategy for the Higgs boson. The Tevatron was a proton/anti-proton collider, with a maximum center of mass energy of 2 TeV, whereas the LHC is a proton/proton collider that will ultimately reach 14 TeV. Because the two accelerators collide different pairs of particles at different energies and produce different types of backgrounds, the search strategies are different. At the Tevatron, for example, the most powerful method is to search the CDF and DZero datasets to look for a Higgs boson that decays into a pair of bottom quarks if the Higgs boson mass is approximately 115-130 GeV. It is crucial to observe the Higgs boson in several types of decay modes because the Standard Model predicts different branching ratios for different decay modes. If these ratios are observed, then this is experimental confirmation of both the Standard Model and the Higgs.

“The search for the Higgs boson by the Tevatron and LHC experiments is like two people taking a picture of a park from different vantage points,” said Gregorio Bernardi, DZero co-spokesperson at the Nuclear Physics Laboratory of the High Energies, or LPNHE, in Paris . “One picture may show a child that is blocked from the other’s view by a tree. Both pictures may show the child but only one can resolve the child’s features. You need to combine both viewpoints to get a true picture of who is in the park. At this point both pictures are fuzzy and we think maybe they show someone in the park. Eventually the LHC with future data samples will be able to give us a sharp picture of what is there. The Tevatron by further improving its analyses will also sharpen the picture which is emerging today.”

This new updated analysis uses 10 inverse femtobarns of data from both CDF and DZero, the full data set collected from 10 years of the Tevatron’s collider program. Ten inverse femtobarns of data represents about 500 trillion proton-antiproton collisions. Data analysis will continue at both experiments.

“This result represents years of work from hundreds of scientists around the world,” said Rob Roser, CDF co-spokesperson and physicist at Fermilab. “But we are not done yet — together with our LHC colleagues, we expect 2012 to be the year we know whether the Higgs exists or not, and assuming it is discovered, we will have first indications that it behaves as predicted by the Standard Model.”

Read frequently asked questions about the Higgs boson.

Notes to editors:

CDF is an international experiment of 430 physicists from 58 institutions in 15 countries. DZero is an international experiment conducted by 446 physicists from 82 institutions in 18 countries. Funding for the CDF and DZero experiments comes from DOE’s Office of Science, the National Science Foundation, and a number of international funding agencies.

CDF collaborating institutions are at http://www-cdf.fnal.gov/collaboration/index.html

DZero collaborating institutions are at http://www-d0.fnal.gov/ib/Institutions.html

Fermilab is a U.S. Department of Energy Office of Science national laboratory, operated under contract by the Fermi Research Alliance, LLC. Visit Fermilab’s website at http://www.fnal.gov.

The plots on this page show the range of masses for the Higgs boson compatible with the latest Tevatron data, in the assumption that the observed excess is caused by the presence of a Higgs boson with the features predicted by the standard theory.

: Observed and expected exclusion limits for a Standard Model Higgs boson at the 95-percent confidence level for the combined CDF and DZero analyses. The limits are expressed as multiples of the SM prediction for test masses chosen every 5 GeV/c² in the range of 100 to 200 GeV/c². The points are joined by straight lines for better readability. The yellow and green bands indicate the 68- and 95-percent probability regions, in the absence of a signal. The difference between the observed and expected limits around 124 GeV could be explained by the presence of a Higgs boson whose mass would lie between 115 to 135 GeV. The CDF and DZero data exclude a Higgs boson between 147 and 179 GeV/c² at the 95-percent confidence level.

: The 4-mile in circumference Tevatron accelerator at Fermilab uses superconducting magnets chilled to minus 450 degrees Fahrenheit, as cold as outer space, to move particles at nearly the speed of light.

: The Tevatron typically produces about 10 million proton-antiproton collisions per second. Each collision produces hundreds of particles. About 200 collisions per second are recorded at each detector for further analysis.

: The three-story, 6,000-ton CDF detector takes snapshots of the particles that emerge when protons and antiprotons collide.

: The three-story, 6,000-ton CDF detector takes snapshots of the particles that emerge when protons and antiprotons collide.

: Control room for CDF where particle sprays from collisions are analyzed.

: Scientists measure the energy, momentum and electric charges of subatomic particles using a three-story assembly of sub detectors wrapped around DZero’s collision area like the layers of an onion.

: Scientists measure the energy, momentum and electric charges of subatomic particles using a three-story assembly of sub detectors wrapped around DZero’s collision area like the layers of an onion.

: Control room for DZero where particle sprays from collisions are analyzed.

: Higgs field can slow down some (otherwise massless) elementary particles—like a vat of molasses slowing down a high-speed bullet. Such particles would behave like massive particles traveling at less than light speed. Other particles—such as the photons of light—are immune to the field: they do not slow down and remain massless.

: At the Large Hadron Collider, which smashes protons into protons, scientists focus on finding signs for the decay of the Higgs particle into two photons.

: At the Tevatron, which made protons and antiprotons collide, scientists focus on finding signs for the decay of the Higgs particle into a bottom quark and anti-bottom quark.

Fermilab scientist Don Lincoln describes the concept of how the search for the Higgs boson is accomplished.

The world’s most precise measurement of the mass of the W boson, one of nature’s elementary particles, has been achieved by scientists from the CDF and DZero collaborations at the Department of Energy’s Fermi National Accelerator Laboratory. The new measurement is an important, independent constraint of the mass of the theorized Higgs boson. It also provides a rigorous test of the Standard Model that serves as the blueprint for our world, detailing the properties of the building blocks of matter and how they interact.

The Higgs boson is the last undiscovered component of the Standard Model and theorized to give all other particles their masses. Scientists employ two techniques to find the hiding place of the Higgs particle: the direct production of Higgs particles and precision measurements of other particles and forces that could be influenced by the existence of a Higgs particles. The new measurement of the W boson mass falls into the precision category.

The CDF collaboration measured the W boson mass to be 80387 ± 19 MeV/c². The DZero collaboration measured the particle’s mass to be 80375 ± 23 MeV/c². The two measurements combined along with the addition of previous data from the earliest operation of the Tevatron produces a measurement of 80387 ± 17 MeV/c², which has a precision of 0.02 percent.

These ultra-precise, rigorous measurements took up to five years for the collaborations to complete independently. The collaborations measured the particle’s mass in six different ways, which all match and combine for a result that is twice as precise as the previous measurement. The results were presented at seminars at Fermilab over the past two weeks by physicists Ashutosh Kotwal from Duke University and Jan Stark from the Laboratoire de Physique Subatomique et de Cosmologie in Grenoble, France.

“This measurement illustrates the great contributions that the Tevatron has made and continues to make with further analysis of its accumulated data,” said Fermilab Director Pier Oddone. “The precision of the measurement is unprecedented and allows rigorous tests of our underlying theory of how the universe works.”

The new W mass measurement and the latest precision determination of the mass of the top quark from Fermilab triangulate the location of the Higgs particle and restrict its mass to less than 152 GeV/c² .This is in agreement with the latest direct searches at the LHC, which constrain the Higgs mass to less than 127 GeV/c², and direct-search limits from the Tevatron, which point to a Higgs mass of less than 156 GeV/c², before the update of their results expected for next week.

“The Tevatron has expanded the way we view particle physics,” said CDF co-spokesperson and Fermilab physicist Rob Roser. “Tevatron experiments discovered the top quark, made precision measurements of the W boson mass, observed B_s mixing and set many limits on potential new physics theories.”

The new measurement comes at a pivotal time, just days before physicists from the Tevatron and the Large Hadron Collider at CERN will present their latest direct-search results in the hunt for the Higgs at the annual conference on Electroweak Interactions and Unified Theories known as Rencontres de Moriond in Italy. The CDF and DZero experiments plan to present their latest results on Wednesday, March 7.

“It is a very exciting time to analyze data at particle colliders,” said Gregorio Bernardi, DZero co-spokesperson and physicist at the Laboratoire de Physique Nucléaire et de Hautes Energies in Paris. “The next few months will confirm if the Standard Model is correct, or if there are other particles and forces yet to be discovered.”

The existence of the world we live in depends on the W boson mass being heavy rather than massless as the Standard Model predicts. The W boson is a carrier of the electroweak nuclear force that is responsible for such fundamental process as the production of energy in the sun.

“The W mass is a very distinctive feature of the universe we live in, and requires an explanation,” said Giovanni Punzi, CDF co-spokesperson and physicist from the University of Pisa. “Its precise value is perhaps the most striking evidence for something “out there” still to be found, be it the Higgs or some variation of it.”

“The measurement of the W boson mass will be one of the great scientific legacies of the Tevatron particle collider,” added DZero co-spokesperson and Fermilab scientist Dmitri Denisov.

Notes for Editors:

Funding for the CDF and DZero experiments comes from DOE’s Office of Science, the U.S. National Science Foundation, and numerous international funding agencies.

CDF collaborating institutions are at http://www-cdf.fnal.gov/collaboration/index.html

DZero collaborating institutions are at http://www-d0.fnal.gov/ib/Institutions.html

Fermilab, America’s only national laboratory fully dedicated to particle physics research, is a U.S. Department of Energy Office of Science laboratory operated under contract by the Fermi Research Alliance, LLC. Visit Fermilab’s website at http://www.fnal.gov.

: The new CDF and Dzero combined result for the W boson mass (vertical section of green oval), combined with the world’s best value for the top quark mass (horizontal section of green oval), restricts the Higgs mass requiring it to be less than 152 GeV/c2 with 95 percent probability. Direct searches have narrowed the allowed Higgs mass range to 115-127 GeV/c2. The grey bar shows the remaining area the Higgs could reside in.

: Scientists measure the energy, momentum and electric charges of subatomic particles using a three-story assembly of sub detectors wrapped around DZero’s collision area like the layers of an onion.

: The Tevatron typically produces about 10 million proton-antiproton collisions per second. Each collision produces hundreds of particles. About 200 collisions per second are recorded at each detector for further analysis.

: Scientists measure the energy, momentum and electric charges of subatomic particles using a three-story assembly of sub detectors wrapped around DZero’s collision area like the layers of an onion.

: The three-story, 6,000-ton CDF detector takes snapshots of the particles that emerge when protons and antiprotons collide.

: Control room for CDF where particle sprays from collisions are analyzed.

: The three-story, 6,000-ton CDF detector takes snapshots of the particles that emerge when protons and antiprotons collide.

: The orange oval shows the previous CDF and DZero combined result for the W boson mass (vertical section of the oval), combined with the world’s best value for the top quark mass (horizontal section of the oval). The green oval shows the new result. The grey bar shows the remaining areas not ruled out for where the Higgs boson could reside.

: Control room for CDF where particle sprays from collisions are analyzed.

: The 4-mile in circumference Tevatron accelerator at Fermilab uses superconducting magnets chilled to minus 450 degrees Fahrenheit, as cold as outer space, to move particles at nearly the speed of light.

Scientists at Fermilab and Berkeley Lab build the biggest map of dark matter yet, using methods that will improve ground-based surveys

Teams from Fermilab and Berkeley Lab used galaxies from wide-ranging SDSS Stripe 82, a tiny detail of which is shown here, to plot new maps of dark matter based on the largest direct measurements of cosmic shear to date. Credit: SDSS.

BATAVIA, Illinois, and BERKELEY, California – Two teams of physicists at the U.S. Department of Energy’s Fermilab and Lawrence Berkeley National Laboratory (Berkeley Lab) have independently made the largest direct measurements of the invisible scaffolding of the universe, building maps of dark matter using new methods that, in turn, will remove key hurdles for understanding dark energy with ground-based telescopes.

The teams’ measurements look for tiny distortions in the images of distant galaxies, called “cosmic shear,” caused by the gravitational influence of massive, invisible dark matter structures in the foreground. Accurately mapping out these dark-matter structures and their evolution over time is likely to be the most sensitive of the few tools available to physicists in their ongoing effort to understand the mysterious space-stretching effects of dark energy.

Both teams depended upon extensive databases of cosmic images collected by the Sloan Digital Sky Survey (SDSS), which were compiled in large part with the help of Berkeley Lab and Fermilab.

“These results are very encouraging for future large sky surveys. The images produced lead to a picture of the galaxies in the universe that is about six times fainter, or further back in time, than is available from single images,” says Huan Lin, a Fermilab physicist and member of the SDSS and the Dark Energy Survey (DES).

Layering photos of one area of sky taken at various time periods, a process called coaddition, can increase the sensitivity of the images six fold by removing errors and enhancing faint light signals. The image on the left show a single picture of galaxies from the SDSS Stripe 82 area of sky. The image on the right shows the same area with the layered effect, increasing the number of visible, distant galaxies. Credit: SDSS.

Melanie Simet, a member of the SDSS collaboration from the University of Chicago, will outline the new techniques for improving maps of cosmic shear and explain how these techniques can expand the reach of upcoming international sky survey experiments during a talk at 2 p.m. CST on Monday, January 9, at the American Astronomical Society (AAS) conference in Austin, Texas. In her talk she will demonstrate a unique way to analyze dark matter’s distortion of galaxies to get a better picture of the universe’s past.

Eric Huff, an SDSS member from Berkeley Lab and the University of California at Berkeley, will present a poster describing the full cosmic shear measurement, including the new constraints on dark energy, from 9 a.m. to 2 p.m. CST Thursday, January 12, at the AAS conference.

Several large astronomical surveys, such as the Dark Energy Survey, the Large Synoptic Survey Telescope, and the HyperSuprimeCam survey, will try to measure cosmic shear in the coming years. Weak lensing distortions are so subtle, however, that the same atmospheric effects that cause stars to twinkle at night pose a formidable challenge for cosmic shear measurements. Until now, no ground-based cosmic-shear measurement has been able to completely and provably separate weak lensing effects from the atmospheric distortions.

“The community has been building towards cosmic shear measurements for a number of years now,” says Huff, an astronomer at Berkeley Lab, “but there’s also been some skepticism as to whether they can be done accurately enough to constrain dark energy. Showing that we can achieve the required accuracy with these pathfinding studies is important for the next generation of large surveys.”

Constrains on cosmological parameters from SDSS Stripe 82 cosmic shear at the 1- and 2-sigma level. Also shown are the constraints from WMAP. The innermost region is the combined constrain from both WMAP and Stripe 82. Credit: SDSS.

To construct dark matter maps, the Berkeley Lab and Fermilab teams used images of galaxies collected between 2000 and 2009 by SDSS surveys I and II, using the 2.5-meter SLOAN telescope at Apache Point Observatory in New Mexico. The galaxies lie within a continuous ribbon of sky known as SDSS Stripe 82, lying along the celestial equator and encompassing 275 square degrees. The galaxy images were captured in multiple passes over many years.

The two teams layered snapshots of a given area taken at different times, a process called coaddition, to remove errors caused by the atmospheric effects and to enhance very faint signals coming from distant parts of the universe. The teams used different techniques to model and control for the atmospheric variations and to measure the lensing signal, and have performed an exhaustive series of tests to prove that these models work.

Gravity tends to pull matter together into dense concentrations, but dark energy acts as a repulsive force that slows down the collapse. Thus the clumpiness of the dark matter maps provides a measurement of the amount of dark energy in the universe.

When they compared their final results before the AAS meeting, both teams found somewhat less structure than would have been expected from other measurements such as the Wilkinson Microwave Anisotropy Probe (WMAP), but, says Berkeley Lab’s Huff, “the results are not yet different enough from previous experiments to ring any alarm bells.”

Meanwhile, says Lin, “Our image-correction processes should prove a valuable tool for the next generation of weak-lensing surveys.”

Fermilab/ University of Chicago scientific papers:

coadd data: http://arxiv.org/abs/1111.6619
photometric redshifts: http://arxiv.org/abs/1111.6620
cluster lensing: http://arxiv.org/abs/1111.6621
cosmic shear: http://arxiv.org/abs/1111.6622

Berkeley Lab/ University of California at Berkeley scientific papers:

coadd data: http://arxiv.org/abs/1111.6958
cosmic shear: http://arxiv.org/abs/1112.3143

Note for Editors:

Lawrence Berkeley National Laboratory addresses the world’s most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab’s scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy’s Office of Science. For more, visit www.lbl.gov.

Fermilab is a national laboratory supported by the Office of Science of the U.S. Department of Energy, operated under contract by Fermi Research Alliance, LLC. Visit Fermilab’s website at http://www.fnal.gov.

The National Science Foundation supported this research. For more information, please visit http://www.nsf.gov/.

The Sloan Digital Sky Survey is the most ambitious survey of the sky ever undertaken, involving more than 300 astronomers and engineers at 25 institutions around the world. SDSS-II, which began in 2005 and finished observations in July, 2008, is comprised of three complementary projects.

Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS Web Site is http://www.sdss.org/.

Batavia, Ill. — A new accelerator research facility being built at Fermi National Accelerator Laboratory will bolster Illinois’ reputation as a technology hub and foster job creation.

Officials broke ground for the Illinois Accelerator Research Center at Fermilab Dec. 16. From left: Bob Kephart, IARC Project Director; Jim Siegrist, associate director of the Office of Science for the Office of High Energy Physics; Michael Weis, DOE Fermilab site manager for the Office of Science; William Brinkman, director of the Office of Science for the DOE; Pier Oddone, Fermilab director; Warren Ribley, director of the Illinois Department of Commerce and Economic Opportunity; Linda Holmes, Illinois state senator; and Michael Fortner, Illinois state representative.

The Illinois Accelerator Research Center (IARC) at the Department of Energy’s Fermilab will provide a state-of-the-art facility for research, development and industrialization of particle accelerator technology. The design and construction of IARC is jointly funded by DOE and the State of Illinois.

“In Illinois we understand the importance of investing in cutting edge technologies, which not only boost our economy, but also secure our role as a major competitor in the global marketplace,” said Governor Quinn. “The best minds in the world are right here, and today we are investing in our future by ensuring that the latest groundbreaking particle research activities will continue to come from Illinois.”

A major focus of IARC will be to develop partnerships with private industry for the commercial and industrial application of accelerator technology for energy and the environment, medicine, industry, national security and discovery science. IARC will also offer unique advanced educational opportunities to a new generation of Illinois engineers and scientists and attract top scientists from around the world.

Located in the heart of the industrial area of the Fermilab campus, IARC will house 42,000 square feet of technical, office and educational space for scientists and engineers from Fermilab, DOE’s Argonne National Laboratory, local universities and industrial partners.

“The IARC facility will help fuel innovation by developing advanced technologies, strengthening ties with industry and training the scientists of tomorrow,” said Dr. William F. Brinkman, Director of DOE’s Office of Science, one of the speakers at today’s groundbreaking. “The Department of Energy welcomes the opportunity to partner with the State of Illinois and looks forward to seeing IARC come to fruition.”

The superstars of the particle accelerator world are the giant research accelerators such as the Large Hadron Collider in Switzerland and Fermilab’s Tevatron, which was permanently shut down in September. Behind the headlines, about 30,000 accelerators are at work around the world in industry, medicine, security, defense and science. All the products that are processed, treated or inspected by particle beams have an estimated annual value of more than $500 billion.

Today’s particle accelerators address many of the challenges confronting our nation in the areas of sustainable energy, a cleaner environment, economic security, health care and national defense. The accelerators of tomorrow have the potential to make still greater contributions. Other nations are already applying these next-generation technologies to current-generation issues, and challenging U.S. leadership in accelerator innovation. The U.S., which has traditionally led the world in the development and application of accelerator technology, now finds its leadership threatened.

“A focused effort and strengthened partnerships between government and industry are required for the United States to remain competitive in accelerator science and technology,” said Fermilab Director Pier Oddone. “IARC will greatly enhance accelerator research and innovation at Fermilab and strengthen our capability to host new international projects. We will also broaden our economic impact on Illinois by working with industry and universities on advanced R&D with many commercial and scientific applications.”

The Illinois Jobs Now! capital bill provided $20 million to the Illinois Department of Commerce and Economic Opportunity to fund a grant for the design and construction of a new building that will form part of the IARC complex.

“The IARC facility positions Illinois at the forefront of the world-wide effort to develop cutting-edge accelerator technologies,” said Warren Ribley, Director of the Illinois Department of Commerce and Economic Opportunity, another speaker at today’s groundbreaking. “It also reinforces the Quinn Administration’s commitment to supporting innovation in Illinois, as well as the creation of 200 high-tech jobs in addition to construction jobs.”

The DOE is also providing $13 million to Fermilab to refurbish an existing heavy industrial building that will be incorporated into the complex, adding 36,000 square feet of specialized workspace.

More information about the Illinois Accelerator Research Center is available at: http://www.fnal.gov/pub/IARC

To learn more about the applications of particle accelerators, visit: http://www.acceleratorsamerica.org/

Fermilab is a national laboratory supported by the Office of Science of the U.S. Department of Energy, operated under contract by Fermi Research Alliance, LLC.

The Illinois Department of Commerce and Economic Opportunity raises Illinois’ profile as a global business destination and nexus of innovation. It provides a foundation for the economic prosperity of all Illinoisans, through the coordination of business recruitment and retention, infrastructure building and job training efforts, and administration of state and federal grant programs.

DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the Unites States, and is working to address some of the most pressing challenges of our time. For more information, please visit the Office of Science website at science.energy.gov.

BATAVIA, Illinois — Two experiments at the Large Hadron Collider have nearly eliminated the space in which the Higgs boson could dwell, scientists announced in a seminar held at CERN today. However, the ATLAS and CMS experiments see modest excesses in their data that could soon uncover the famous missing piece of the physics puzzle.

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.

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.

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 GeV by the ATLAS experiment, and 115-127 GeV by CMS. Tantalising hints have been seen by both experiments in this mass region, but these are not yet strong enough to claim a discovery.

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. Both ATLAS and CMS have analysed 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.

Hundreds of scientists from U.S. universities and institutions are heavily involved in the search for the Higgs boson at LHC experiments, said CMS physicist Boaz Klima of the Department of Energy’s Fermi National Accelerator Laboratory near Chicago. “U.S. scientists are definitely in the thick of things in all aspects and at all levels,” he said.

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 CMS and ATLAS experiments, the vast majority via an ultra-high broadband network that delivers LHC data to researchers at universities and national laboratories across the nation . The Department of Energy’s Office of Science and the National Science Foundation provide support for U.S. participation in these experiments. Fermi National Accelerator Laboratory is the host laboratory for the U.S. contingent on the CMS experiment, while Brookhaven National Laboratory hosts the U.S. ATLAS collaboration.

Over the coming months, both the CMS and ATLAS 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.

“We’ve now analyzed all or most of the data taken in 2011 in some of the most important Higgs search analyses,” said ATLAS physicist Rik Yoshida of Argonne National Laboratory near Chicago. “I think everybody’s very surprised and pleased at the pace of progress.”

Higgs-hunting scientists on experiments at U.S. particle accelerator the Tevatron will also present results in March.

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

Even if the 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. 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 .

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.

Notes for editors:

Media contacts:

Brookhaven National Laboratory – Karen McNulty Walsh, kmcnulty@bnl.gov, 631-344-8350

Fermi National Accelerator Laboratory – Tona Kunz, tkunz@fnal.gov, 630-840-3351

Information about the US participation in the LHC is available at http://www.uslhc.us. Follow US LHC on Twitter at twitter.com/uslhc.

Brookhaven National Laboratory is operated and managed for DOE’s Office of Science by Brookhaven Science Associates and Battelle. Visit Brookhaven Lab’s electronic newsroom for links, news archives, graphics, and more: http://www.bnl.gov/newsroom.

Fermilab is a U.S. Department of Energy Office of Science national laboratory, operated under contract by the Fermi Research Alliance, LLC. Visit Fermilab’s website at http://www.fnal.gov.

The National Science Foundation focuses its LHC support on funding the activities of U.S. university scientists and students on the ATLAS, CMS and LHCb detectors, as well as promoting the development of advanced computing innovations essential to address the data challenges posed by the LHC. For more information, please visit http://www.nsf.gov/.

CERN, the European Organization for Nuclear Research, is the world’s leading laboratory for particle physics. It has its headquarters in Geneva. At present, its Member States are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, the Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. Romania is a candidate for accession. Israel is an Associate Member in the pre-stage to Membership. India, Japan, the Russian Federation, the United States of America, Turkey, the European Commission and UNESCO have Observer status.