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ATLAS and CMS experiments present Higgs search status

By Various experts

It's far too early to say whether ATLAS and CMS have discovered the Higgs boson, but updated results are generating a lot of interest in the particle physics community.

Dr. Philip Schuster, Faculty, Perimeter Institute for Theoretical Physics, Canada
"For 40 years, physicists have searched for the origin of the weak interactions, and the mechanism that generates mass for fundamental particles in the Universe. These phenomena are responsible for basic features of our world ranging from the long lifetime of the Sun to the very existence of atoms. Today, it looks like we have promising evidence that there is actually a Higgs mechanism in Nature, and the particle associated with that mechanism may finally be showing itself. Going forward, physicists will gather more evidence needed to prove that a Higgs particle exists. Understanding the properties of the Higgs mechanism and where it comes from will be an important goal for the next decade."

Dr Alan Barr of Oxford University’s Department of Physics, ATLAS UK physics coordinator
“It is a testament to the superb performance of the LHC that we are already finding hints that might be indicative of Higgs bosons so early in the machine’s lifetime. The results are not yet conclusive, but during the next year we will know whether the Higgs boson exists in the form predicted by the “Standard Model” of particle physics. The analysis has to be done very carefully, since in scientific research the most interesting results are often found in unexpected places.’

“We must bear in mind that the Standard Model is known to be incomplete, since it describes only that 5% of the universe that is made of atoms. What the LHC will tell us about the other 95% of the universe is likely to be an open question for many years to come.”

Prof Dan Tovey, Professor of Particle Physics at the University of Sheffield and spokesman for ATLAS
"While these results do not provide conclusive proof of the existence of the Higgs boson the fact that broadly similar hints have been seen by two competing experiments using several different complementary techniques is very suggestive. With much more data due next year it won't be long before we can answer this question once and for all."

Prof Geoff Hall, Professor of Physics at Imperial College London and UK spokesperson for CMS
"At the beginning of this year, we had little idea of what mass the Higgs boson might have, assuming it really existed. Now the situation is completely changed, as a result of less than one year of LHC data, and the region where the Higgs may be found has been narrowed from about 500 GeV to 10-20 GeV. There are also strong hints that the Higgs may really exist in that narrow range. This is quite remarkable. The successful and rapid analysis shows how well the experiments work and how ready for the complex studies the scientists are, after about twenty years of building and preparation. It has been a huge effort. It is too soon to draw conclusions but it certainly begins to feel as though we are on the verge of momentous progress, confirming the Standard Model and shedding new light on deeper ideas. Of course, it is tempting to speculate how particle physics will change with a Higgs discovery but most of us are still focused on verifying that it is really found and, if so, to prove what kind of Higgs it is – eg Standard Model or supersymmetric. This will require a lot more data in the coming year, and even after that for some years to come."

Prof Themis Bowcock, Head OF Particle Physics at the University of Liverpool
“The CERN results on the Higgs boson have the scientific world agog. Have they or have they not seen the elusive particle sometimes called the God Particle? First proposed in the 1960s, this particle plays a crucial role in the evolution of the Universe from the Big Bang to the way we see it today.

“Our understanding of nature and its fundamental forces is known as the Standard Model. For the last 40 years it has allowed us to understand phenomena such as light, the way the sun burns, and how atoms and nuclei are held together.

“The Standard Model relies on a particle called the Higgs boson which interacts with other particles making some very heavy whilst leaving others light. This shapes the Universe we know today. However to date no-one has found direct evidence of the Higgs.

“The ATLAS and CMS experiments at the LHC have come as close as anyone to observing the Higgs and now both have presented small but significant signals. It is possible that each observation is simply a statistical fluke, a fluctuation in the background, mimicking a Higgs signal. But the fact that ATLAS and CMS independently agree on the possible Higgs mass substantially increases the overall significance of the results.

“If the Higgs observation is confirmed, through analysis of data to be collected next year, this really will be one of the discoveries of the century. Physicists will have uncovered a keystone in the makeup of the Universe – one whose influence we see and feel every day of our lives.”

Dr Alan Barr, physics coordinator of the ATLAS UK collaboration
“Our understanding of physics at the microscopic level is described by a beautiful piece of mathematics known as the “Standard Model”. For that mathematical model to work correctly, various pieces must work together, like a well-engineered machine. The Higgs boson is a crucial part of the machinery of the subatomic world.

“This evidence of the existence of a Higgs boson suggests that the mathematically beautiful theory of the subatomic world is more than just an elegant model, and that it really does seem to describe the universe around us.”

Dr Stephen Haywood, Head of the Atlas Group at the STFC Rutherford Appleton Laboratory
“This is what many of us have been working towards for the best part of 20 years. If the first inklings of the Higgs boson are confirmed, then this is just the start of the adventure to unlock the secrets of the fundamental constituents of the Universe.”

Dr Claire Shepherd-Themistocleus, Head of the CMS Group at the STFC Rutherford Appleton Laboratory
“We are homing in on the Higgs. We have had hints today of what its mass might be and the excitement of scientists is palpable. Whether this is ultimately confirmed or we finally rule out a low mass Higgs boson, we are on the verge of a major change in our understanding of the fundamental nature of matter.”

Prof Stephan Söldner-Rembold, Head of the Particle Physics Group at the University of Manchester
“ATLAS and CMS have presented an important milestone in their search for the Higgs particle, but it is not yet sufficient for a proper discovery given the amount of data recorded so far. Still, I am very excited about it, since the quality of the LHC results is exceptional.

“The Higgs particle seems to have picked itself a mass which makes things very difficult for us physicists. Everything points at a mass in the range 115-140 GeV and we concentrate on this region with our searches at the LHC and at the Tevatron.

“The results indicate we are about half-way there and within one year we will probably know whether the Higgs particle exists with absolute certainty, but it is unfortunately not a Christmas present this year. The Higgs particle will, of course, be a great discovery, but it would be an even greater discovery if it didn't exist where theory predicts it to be. This would be a huge surprise and secretly we hope this might happen. If this is case, there must be something else that takes the role of the “standard” Higgs particle, perhaps a family of several Higgs particles or something even more exotic. The unexpected is always the most exciting.”

Source: Science Media Centre / AusSMC