Latest analyses from the Large Hadron Collider boosts case for particle.
Today the two main experiments at the Large Hadron Collider (LHC), the world’s most powerful particle accelerator, submitted the results of their latest analyses. The new papers boost the case for December’s announcement of a possible Higgs signal, but let’s not get too excited.
First, there are no new data in there — the LHC stopped colliding protons back in November, and these latest results are just rehashes of that earlier run. In the case of the Compact Muon Solenoid (CMS), physicists have been able to look at another possible kind of Higgs decay, and that allows them to boost their Higgs signal from 2.5 sigma to 3.1 sigma. Taken together with data from the other detector, ATLAS, Higgs’ overall signal now unofficially stands at about 4.3 sigma. In other words, if statistics are to be believed, then this signal has about a 99.996% chance of being right.
It all sounds very convincing, but keep your hat on, because the fact is that statistical coincidences happen every day. Over at Cosmic Variance, Sean Carroll points out that there is a 3.8 sigma signal in the Super Bowl coin toss. Does that mean that they’ve discovered a super-partner to the bowl? No. (If you don’t get that joke, don’t worry, it was written only as punishment for those who would.)
After the LHC starts again this spring, we’ll be much closer to knowing what’s actually going on. Right now, scientists are meeting in Chamonix, France, to decide at what power to run the collider this coming year. The latest rumours are that the machine will push from 7 to 8 teraelectronvolts, and it will also increase its luminosity (the number of collisions per pass).
For a little more context about what’s going on, check out this video of my trip back in November:
Higgs result means elegant universe is back in vogue
AFTER a short spell on the rocks, a mathematically elegant view of the universe is back in vogue. Recent hints of the Higgs boson at the Large Hadron Collider help explain why we have not seen evidence for the beautiful theory of supersymmetry yet - and point to fresh ways to focus the search.
Supersymmetry, or SUSY, is an extension to the standard model of how particles and forces interact. Via elegant equations, it posits that every fundamental particle - including quarks, electrons, photons and neutrinos - has a heavier, as yet unseen “superpartner” with slightly different properties (see diagram). This smooths some embarrassing wrinkles in the standard model. However, not one superpartner has yet shown up at the LHC, the particle smasher at CERN near Geneva, Switzerland, prompting fears that, despite its beauty, SUSY could be wrong.
That changed on 13 December, when LHC physicists reported that they might have found traces of the Higgs boson, the standard-model particle that is thought to give all others mass. The data suggested a mass for the Higgs close to 125 gigaelectronvolts, 133 times that of the proton and too light for a Higgs to survive without a heavier companion particle, which could be a superpartner.
Finding the Higgs is the Beginning of a Long Quest to Discover a Theory of Everything
The announcement this week that two groups of scientists have narrowed the search for the elusive Higgs Boson made headlines around the world. Next year, physicists actually hope to find the Higgs particle.
But is this an end to physics? No - It’s just the beginning. The Higgs particle is the last piece of the jigsaw puzzle, called the Standard Model of particles although we have yet to confirm its existence.
Once found, it will complete this picture of known sub-atomic particles. However, the Standard Model can only explain 4% of the matter/energy content of the universe. The rest is made of dark matter (23%) and dark energy (73%). We know that atoms make up a distinct minority in this universe and 96% of the univese is NOT made of atoms (and the particles of the Standard Model). Even more glaring, the Standard Model does not contain gravity, yet gravity is the most pervasive force in the universe.
Physicists at the Large Hadron Collider, a particle accelerator near Geneva, Switzerland, report that they’re hot on the trail of an elusive elementary particle known as the Higgs boson.
It’s only a matter of time before they’ll have the infamous “God particle” in handcuffs, they say. But after years of particle- and head-bashing at the LHC, one burning question is whether there’s an easier way to do this. Instead of constructing an 18-mile-long, high-energy collider to generate a Higgs particle from scratch, couldn’t we just go look for one in nature?
And if so, where in space might it be?
John Gunion, first author of “The Higgs Hunter’s Guide” (Basic Books, 1990) and a professor of physics at the University of California, Davis, said Higgs bosons regularly pop into existence all over space. Quantum fluctuations — momentary bursts of energy from nowhere that are permitted by the rules of quantum mechanics — cause pairs of the particles to spontaneously arise out of the vacuum, then annihilate each other an instant later. Because these freebie Higgs have extremely high energies, the rules of quantum mechanics dictate that they don’t get to stick around for as long as lesser particles would. So, if you’re a Higgs hunter, how much time do you have to catch these bosons before they disappear? “Shorter than 1-trillionth-of-1-trillionth of a second,” Gunion said. [Gallery: Search for the Higgs Boson]
A Tantalizing Glimpse That May Be the Higgs Boson — But Wait For 2012
Physicists at CERN may have caught the first whiffs of the elusive Higgs boson, researchers announced this morning, but more numbers must be crunched before anyone will claim its discovery. Bumps in signals at the Large Hadron Collider are not surefire proof of the so-called god particle, at least not yet — but at the very least they’re enough to keep faith in our modern theories of physics.
Two detectors have been sifting the detritus from ultra-high-energy proton collisions at the LHC, and so far they have seen “tantalizing hints” of the Higgs, physicists said at a news conference. The particle weighs about 125 to 126 giga-electronvolts, according to evidence from the Atlas and CMS detectors, respectively. That’s about 125 times heavier than a proton.
If it exists at all, it must weigh between 117 to 127 GeV, according to the new measurements. That relatively narrow band is the result of previous LHC (and Tevatron) experiments that already ruled out other suspected sizes.
The news is all in the title of this post. I know some of my colleagues will disagree, and the message is by no means the one that officially CERN wants to deliver nor publicized by the press. But “Firm Evidence” is what I personally would call the now public results of the ATLAS and CMS experiments in their multi-pronged searches of a Standard Model Higgs boson.
I will explain why below, using some of the most important graphs shown by Fabiola Gianotti and Guido Tonelli today; but before I continue, let me tell you why I have stressed “Standard Model” above. A particle which behaves like the Standard Model Higgs, both in the way it is produced and in the way it decays, cannot in my opinion be considered a hint of Supersymmetry just because some of the SUSY theories do predict that the lightest of the 5 or more Higgs particles will behave like a Standard Model Higgs boson!
So, SUSY enthusiasts should remain quiet for the time being, especially since large swaths of parameter space are being directly canceled by the CMS and ATLAS searches -for instance, a 500 GeV gluino is by now almost totally excluded (it remains possible in very specialized and ad-hoc scenarios) and Gordy Kane no later than one year ago was willing to put his money on it.
Rumor Mill: LHC Researchers Expect First Glimpse of the Higgs Boson Next Week
There’s no official announcement yet—that comes next week—but word on the street and around the cafeteria at CERN says that scientists may announce that they’ve glimpsed the elusive Higgs boson at a meeting scheduled for Tuesday. Researchers at the Large Hadron Collider have been saying that they are closing on the so-called God Particle for a while now, and while a rock-solid 5-sigma event isn’t in the offing we might finally see our first experimental data that points toward a real Higgs sighting.
Why all the buzz all of a sudden? Firstly, next week’s meeting will see presentations by researchers from both the ATLAS and CMS experiments, the two main experiments at the LHC charged with finding the Higgs. That’s not particularly out of the ordinary, but rumor has it senior scientists from each experiment will be presenting, something that is usually delegated further down the chain of command.
Further, there’s the reportedly palpable sense of anticipation at CERN itself, where reporters on site are reporting a growing sense of excitement. Television news show Newsnight managed to grab quotes from a few scientists at CERN this week that point toward a feeling of anxious elation. READ FULL ARTICLE AT POPSCI
Scientists May Be Closing in on the Higgs Boson Particle
Particle physics has played out over the last half-century or so like a seasoned crime drama: scientists would use accepted theories and their deductive skills to predict whether a particle should exist, build colossal particle accelerators to find it, then catch it red-handed by smashing atoms together in a spectacular final act. For the denouement, Nobel prizes are usually awarded.
That sequence has been played out time and again, but the investigation is progressing at glacial pace in pursuit of one high-profile culprit: the Higgs boson. Long predicted as the agent responsible for bestowing some fundamental particles with mass, the Higgs would only give itself away at tremendous energies — too much for particle accelerators to produce.
Until now. Europe’s Large Hadron Collider (LHC), which has been consistently operating since 2009 after a botched grand opening the previous year, is theoretically capable of seeing hints of the Higgs boson, and now the rumor among the physics community is that it’s done just that. A two-part lecture scheduled for Dec. 13 at the European Organization for Nuclear Research (CERN) has the tantalizing title, “Update on the Standard Model Higgs searches.”
Could a Higgs Boson Announcement Be Imminent From the LHC?
Physicists at the Large Hadron Collider could be getting an early Christmas present: the Higgs boson. According to the latest rumors, scientists at the LHC are seeing a signal that could correspond to a Higgs particle with a mass of 125 GeV (a proton is slightly less than 1 GeV).
Public talks are scheduled to discuss the latest results from ATLAS and CMS, two of the main LHC experiments, on Dec. 13. This follows one day after a closed-door CERN council meeting where officials will get a short preview of the findings, whatever they may be.
“Chances are high (but not strictly 100%) that the talks will either announce a (de facto or de iure) discovery or some far-reaching exclusion that will be really qualitative and unexpected,” wrote theoretical physicist Lubos Motl on his blog.
Motl also mentioned that an internal email sent to the CERN community suggests that results on the elusive Higgs — which is required under the Standard Model of particle physics to provide mass to different particles — will be inconclusive. This could mean that the finding is below the five-sigma threshold needed to definitively declare a discovery in physics.
But if the rumors are true, and the Higgs has been seen at 125 GeV, it could bolster the idea that there is physics beyond the Standard Model that describes the behavior of subatomic particles. A 125 GeV Higgs is lighter than predicted under the simplest models and would likely require more complex theories, such as supersymmetry, which posits the existence of a heavier partner to all known particles.
