Tevatron experiments report latest results in search for Higgs boson

Mar 07, 2012
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 presense 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.

(PhysOrg.com) -- 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 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 , 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 in the quest to understand the building blocks of nature.”

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

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 , 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, 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.”

Explore further: Experiment with speeding ions verifies relativistic time dilation to new level of precision

More information: Higgs boson FAQ (PDF)

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Kinedryl
1.6 / 5 (5) Mar 07, 2012
These data are very similar to those originally reported in July 2011 for 9 /fb, just the sigma increased by whole unit. I do perceive a bit suspicious, if statistical significance of results increases ten-times with adding of another 10% of data...;-) Apparently there is a strong political pressure for confirming the latest CERN results...

http://www.symmet...article/

Many physicists aren't very sure, if these findings really correspond the Higgs boson predicted with Standard Model. The signal manifests itself pronouncedly in dilepton channel instead of Z-boson channel and its intensity is higher then expected too..
LeeSawyer
5 / 5 (6) Mar 07, 2012
Actually, Kinedryl, wouldn't the the overall consistency in shape of the exclusion limit actually make you _less_ suspicious ;-) ? In any event, it is not simply a 10% increase in data - in some channels the increase is much more than that, and many systematic errors have been reduced. This ties-in directly with the much improved W mass measurement released last week.

Obviously, one of the firsts tests, after the Higgs is confirmed, is to measure its properties and to try to determine if it is a single Standard Model Higgs, or part of a larger Higgs sector predicted by SuperSymmetry or extensions of the Standard Model.
Egleton
1 / 5 (1) Mar 07, 2012
I am not suspicious. I am confused.
If massive particles interact with the Higgs field why do they resist changes in their momentum? Why does a bullet not stop if fired in a vacuum?

This Higgs field of Higgs particles should absorb the energy of massive particles passing through it. I understand that mass-less particles that do not react with the H field will keep on moving unimpeded.

Exactly how does the Higgs particle sustain the mass and momentum of a hadron?

This Higgs field is an impenetrable fog.
Kinedryl
1 / 5 (2) Mar 07, 2012
In any event, it is not simply a 10% increase in data
The first graph from March 2011 contains data of 8.6 /fb integrated luminosity, the second one at the title of article for 10 /fb. The (10 minus 8.6) over 10 is 14%. In addition, Tevatron collider was closed closed in Sept 2011 - so it simply couldn't upgrade these ten years old datasets more than just by just a few percents during four months.
wouldn't the the overall consistency in shape of the exclusion limit actually make you _less_ suspicious
This is just my point - the data remained the same, but their reliability increased ten-times...;-) Btw the location of Higgs boson peak is at 130 GeV, not 125 GeV. It indicates, the data from both colliders are still loaded with lotta noise.
Kinedryl
1 / 5 (3) Mar 07, 2012
After all, these graphs are confusing, as the real curve of Higgs boson scattering data drawn at scale appears in this way. For comparison cold fusion data are ignored even when they provide the COP peak in 600% scale - it just illustrates the scope of double standards, which are applied for evaluation of experimental results in mainstream and non-mainstream physics.
Callippo
1 / 5 (5) Mar 07, 2012
BTW In dense aether model the same foamy fluctuations of vacuum observable at the sky as a dark matter foam should emerge at the quantum scale, because the dispersion model is essentially symmetric around human observer scale. They do manifest with typical power spectrum, corresponding the dodecahedral symmetry of this foam, which should have its counterpart at the "Higgs boson" spectrum.
Callippo
1 / 5 (1) Mar 08, 2012
In this context it's interesting, the supersymmetry models predict not just only one mass of Higgs boson, but many of them. For example the simplest supersymmetric extension of Standard Model predicts as many Higgs bosons, as many peaks we are observing at the power spectrum of CMBR (i.e. five ones). In minimal Supersymmetric extension (MSSM) two Higgs doublets result in five physical states, the masses of which can be determined by two parameters.
5thabove
1 / 5 (1) Mar 09, 2012

The problem with finding the God Particle is it has Mass found in the weak force and finding it is like finding a CPU in software. Look at this:

CERN neutrinos @ v-c/c=2.48e-5 sec in 453.6 miles = Stanford's SLAC E158 asymmetry of the weak force @ 2.48e-5 sec in 456.3 miles with a .20e-5 harmonic comma, the distance CERNs neutrinos traveled showing the asymmetry in space as well as in time as it must since space is relative to time. It is based on a ratio obtained by adding the distance light travels in one hour to the distance light travels in one thousand years called the asymmetry of the weak force SLACs E158 team of experts discovered, and then reducing it to the distance light travels in only 453.6 miles. (Its much easier to comprehend the ratio @ 3.6 seconds added to 31,556,952 seconds in a 365.2425 day year and then add it's it value to 453.6 miles)

How can this "unrelated" data match? It was not a broken cable that caused v-c/c=2.48e-5! That's politics

John F. Hendry
5thabove
1 / 5 (1) Mar 09, 2012
Note: Cohan and Glasgow predicted an asymmetry of space. That figure shows a .20e-5 harmonic comma CERN and SLAC E158 data created which I stated for years and knew had to be there because if you add the asymmetry of the weak force to time you have to add it to space too, and that's a well-known fact of harmonics in music theory too dealing with (tonal) space obviously connected in harmonic phase timing to consciousness. You can't have one asymmetry without the other if space is relative to time.

Showing the cause of the speed of light is the first step in resolving the observation induced misconceptions of the data being obtained. Quantum physics is not a game of dice as Einstein said, its a two sided card game where a third side requires another card that has its own relative flip side that gives you the information of the card below it by understanding its phase in time. The weak force asymmetry space separates the cards so nothing is missing or left to chance.

John F. Hendry^^
Kinedryl
1 / 5 (2) Mar 09, 2012
it is like finding a CPU in software
Yes, it's a nice analogy. In AWT the finding of Higgs boson correspond the detection of underwater with surface ripples, as the water surface always appears void and empty for them - no matter, how the surface is actually deformed. But the dispersion of surface ripples introduces limits for it at both low, both high distance/energy density scale - their solitons undergo hypersphere packing geometry, which can be described with Lie gauge groups and their root vectors introduce a characteristic dodecahedral imprint into both CMBR noise at large scales, both quantum noise at low scales.
5thabove
1 / 5 (1) Mar 09, 2012
I am showing that CERN was correct in their neutrino measurements and what caused v-c/c=2.48e-5 in 453.6 miles to occur: the asymatry of the weak force.

What this means most importantly is recognizing a true inertial frame of reference exists in Nature to measure time from and separation of the weak force from the strong force by {a} weak force asymatry while still retaining anti-particle atomic phase timing in observation of a speed of light clock running fast @ 3.6 seconds a year due to {a} wf asy. E=m {a}c2, F=m {a}a, etc.

That adds the needed cosmological constant, the error in Newton's law was known and I said it applied to Ohm's Law down the line.

The location of Mass is found in the weak force.

The reason for the discrepancy between matter and anti-matter is due to a single Mass anti-particle source creating matter relative to time one atom at a time always moving on to the next in time dilated Universe @3.6sec a year.

This changes physics thanks to CERN.

John F. Hendry^^
5thabove
1 / 5 (1) Mar 09, 2012
Thanks...the calculations are posted on Nature's forum if want to see them. Search my name on Google...even v-c/c=2.48e-5 gets you there. SLAC E158 had about 3 entries before I posted that and then everyone stopped saying it was an error and SLACs Google pages went up about 10 a day till they got to 100 pages full so I could watch how many people started looking at the WF Asy data. Been saying it for years but no one paid attention till this happened...small part of my work.

John^^
Callippo
1 / 5 (1) Mar 10, 2012
Sean_W
1 / 5 (1) Mar 12, 2012
Gravitons for gravitational mass, the Higgs for inertial mass... is there any relation between these two things? Do they affect one another at all? And is there a picture of the fine scale structure of spacetime that is compatible with these particles? I suppose I'm jumping the gun with these questions. Without advanced calculus I probably won't understand the answers when they arrive anyway but it would be reassuring to know that someone understands it all.
Callippo
1 / 5 (2) Mar 12, 2012
Without advanced calculus I probably won't understand the answers when they arrive anyway but it would be reassuring to know that someone understands it all.
The advanced calculus will not help you with understanding, if you couldn't follow every step of it at the intuitive level. In dense aether model the space-time is always formed with many another gradients of space-time, which slow down the energy spreading and doing the space for us. But from the same reason every space is filled with tiny density fluctuations which do behave like the Brownian noise at the seemingly flat water surface. These fluctuations do manifest in two main ways: 1) they exert the omnipresent pressure to all massive objects. The place between these objects is shielded and the objects are pushed into it - this is what the gravity means in dense aether model. 2) they disperse the waves exchanged with massive objects i.e. they're giving them a rest mass and inertia. Is it difficult to understand it? Nope.
5thabove
1 / 5 (1) Mar 12, 2012
Sean W said: "Gravitons for gravitational mass, the Higgs for inertial mass.."

If you turn your question around a simple picture forms. You have Mass..call it Mr. Higgs as some joke comparing it to the Beatles's Eggman but realize it's Mass occupying it's own space dead or alive...doesn't matter to see the picture, and it's in oscillation because of it's own gravity flowing within itself and as it oscillates the space left in its wake created relative to time (like a pendulum) has energy following through the space created that moves in two directions relative to two moving phases in time in sync with Mass: up and down. Mass "sees" in one direction and going up its "unhappy" losing energy as an electron, and coming back down its "happy" gaining it back as the "missing graviton needed for a force carrier of gravity". The force carrier of gravity is space and that 4th oscillation phase is where Mass is 1/4 of the time with energy left behind in sync. Space and water are a lot alike. JFH
5thabove
1 / 5 (1) Mar 12, 2012
Note: That's just a simple analogy of Mass and time creating an atom and when Mass stops at each end of the oscillation cycle it gets bigger because it stopped. Its space/size is relative to time so if it moves @ SOL to displace the same space it must get smaller at all points and stretch out. The neutron at the top measures a little bigger because it forms after the proton phase and time used to measure it has expanded. We see this expansion of time/space in both worlds, big and small. Space is literally relative to time in size, and time is created by Mass oscillation within the weak force that transfers it energy when neutron forms via the photon/neutrino space into the strong force, so I am talking about the anti-particle side of matter where Mass is found.

JFH^^