new subatomic particles
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Physicists just discoveredtwo new subatomicparticles. Here's whythat matters.Updated by Joseph Stromberg on November 26, 2014, 9:00 a.m.
ET @josephstromberg [email protected]
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A visitor to the Large Hadron Collider, the particle accelerator where the new particles were
observed.(Peter Macdiarmid/Getty Images)
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Last week, physicists at the Large Hadron Collider—
the particle acceleratorused to discover the Higgs Boson in 2012— announced that they discoveredtwo subatomic particles, the baryons Xi_b'- and Xi_b*-.
If that sentence leaves you feeling just a bit mystified, you're not alone.
Physics might be the most complex of all scientific fields, and at times, it can behard to explain its fundamental concepts in basic English. But with the helpof Patrick Koppenburg — one of the scientists at the Large Hadron Collider
(LHC) involved in this new discovery—
here's a comprehensible guide to thesenew particles, the Higgs, and the ongoing experiments at the LHC as a whole.
1) What was just discovered?On November 19, scientists announced that, using data collected in 2012, they'dobserved two new varieties of a class of tiny subatomic particlescalled baryons. You've probably already heard of two other types of baryons:protons and neutrons.
The thing that unites protons, neutrons, and the two new baryons is that they'reall made out of three even-smaller particles called quarks — one of thefundamental building blocks of all matter.
Quarks themselves come in six "flavors" (called up, down, strange, charm,bottom, and top). A proton is built from two up quarks and one down quark, whilethe new baryons are both made from one down quark, one bottom quark, andone strange quark.
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A diagram showing the 17 fundamental particles of the standard model. (MissMJ)
These two new baryons weren't a huge discovery, as new particles like this arefound a few times a year. What's more, the existence of these baryons waspredicted by the standard model, our current, best formula for predicting thebehavior of all particles.
Seeing them firsthand, however, is useful. "It's quite easy to predict their
existence, but it's much more difficult to predict their mass," Koppenburg says."Observing them allows us to measure it." That data allows physicists to betterunderstand how the strong nuclear forceholds quarks together.
Under normal conditions, the three quarks that make up these new baryonsnever combine in this particular way. But conditions in the Large Hadron Colliderare anything but normal.
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2) What is the Large Hadron Collider?
A tunnel at the LHC. (Fabrice Coffrini/AFP/Getty Images)
The LHC, which was completed in 2008, is the world's largest particle
accelerator. It's a nearly 17-mile-long tunnel ring that lies below the border ofFrance and Switzerland and allows physicists to conduct some pretty intenseexperiments.
In essence, these experiment involve shooting beams of particles around thering, using enormous magnets to speed them up to 99.9999 percent of the speedof light (causing them to whip around the ring about 11,000 times per second),then crashing them together.
The huge amount of energy present in these collisions leads the particles to
break apart and recombine in some pretty exotic ways. The recombinations—
along with other data collected during the collisions — allow physicists to testpredictions made by the standard model.
3) What is the Higgs boson?
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Data from one of the particle detectors at the LHC. (Fabrice Coffrini/AFP/GettyImages)
The Higgs boson, a type of particle, is one of the primary reasons the LHC wascreated. "In building the LHC, what we really hoped to do was either find theHiggs, or be able to exclude its existence," Koppenburg says.
In July 2012, after analyzing the results of a collision between protons, theyfound it.
The particle is evidence of a force called the Higgs field: an invisible field thatpervades all space and exerts a drag on every particle. This drag is why weperceive particles to have mass— a resistance to being moved.
The Higgs field is a sort of keystone of the standard model, as it allows the rest ofits equations to make a whole lot more sense.
4) What's the point of all this?Both the Higgs-related research and more recent work at the LHC are aimed atone goal: pushing the standard model to its limits, to see where it's correct andwhere it breaks down.
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That's because the standard model is incomplete. "It's extremely efficient atmaking predictions, but we physicists don't really like it," Koppenburg says.
THE GOAL IS TO PUSH THE STANDARD MODEL TO ITS LIMITS, TO SEEWHERE IT BREAKS DOWN
Though the standard model accurately describes the behavior of particles inmost ways, it doesn't account for the force of gravity, or exotic substances suchas dark matter and dark energy. It also doesn't mesh well with our theories aboutthe birth of the universe.
In other words, the standard model is the best description we currently have ofhow all objects behave, but as Koppenburg says, "it must be wrong somewhere."
The discovery of the Higgs—
along with last week's discovery of the two newbaryons— served to confirm the current model. That sort of data is useful,because it provides real evidence for our calculations, showing we're on the righttrack so far in trying to understand the universe.
But future discoveries that aren't predicted by the standard model might be evenmore useful, as they could indicate which aspects of it need to be changed.
5) What's next for the LHC?
A tunnel in the LHC. (Vladimir Simicek/isifa/Getty Images)
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Currently, the LHC is shut down for a series of upgrades. It will open sometime inearly 2015, capable of producing much higher-energy collisions than before.
These collisions will allow scientists to keep discovering new subatomic particles,and also look more closely at the Higgs boson and observe how it behaves under
different conditions.
"We're hoping to find things that were not predicted by the standard model,"Koppenburg says. "Perhaps particles that are so heavy that they haven't beenproduced before, or other kinds of deviations."
The right kinds of deviations, he and other physicists hope, will allow us toimprove our model. Someday, this sort of work could even lead to the creation anew model that fully describes the behavior of all objects in the universe.