Finally, Something non-political.
Look for a major announcement tomorrow (12/13/2011) from C.E.R.N. with respect to new data from the Large Hadron Collider.


The announcement, planned for 8 a.m. EST (2 p.m. CET), will address the status of the search for the elusive Higgs boson particle, sometimes called the "God Particle" because of its importance to science.

Background

Q. What is the Higgs and why is it important?

A. The name Higgs refers to at least four things. First of all, there is a Higgs mechanism, which is ultimately responsible for elementary particles’ masses. This is certainly one of the trickier aspects of particle physics to explain, but essentially something like a charge — not an electric charge — permeates the vacuum, the state with no particles.

These “charges” are associated with a Higgs field. As particles pass through this field they interact with the “charges,” and this interaction makes them act as if they had mass. Heavier particles do so more, and lighter particles do so less. The Higgs mechanism is essential to the masses of elementary particles.

The Higgs particle, or Higgs boson, is the vestige of the simplest proposed model of what created the Higgs field in the first place. Contrary to popular understanding, the Higgs field gives mass — not the Higgs boson. But a discovery of the Higgs boson would tell us that the Higgs mechanism is right and help us pin down the theory that underlies both the Higgs mechanism and the Standard Model.

In the simplest implementation of the Higgs mechanism, the experimental consequence is the Higgs boson. It is the particle that the experimentalists are now searching for.

Of course, Higgs is also the name of the person, Peter Higgs, who first developed the underlying theory (along with five others who will be in contention for the Nobel Prize if and when the Higgs particle is discovered.)

Q. How will we know it when we find it?

A. In the simplest implementation of the Higgs mechanism, we know precisely what the properties of the Higgs boson should be. That’s because of its connection to the Higgs mechanism, which tells us that its interactions with any particular particle are determined by that particular particle’s mass.

Knowing the interactions, we can calculate how often the Higgs boson should be produced and the ways in which it should decay. It can decay only into those particles that are light enough for energy to be conserved. Roughly speaking, the Higgs boson decays into the heaviest such particles the most often, since it interacts with them the most strongly.

What we don’t know, however, is the Higgs boson’s mass. The Higgs boson decays differently, depending on its mass, since a heavier Higgs boson can decay in ways that a light Higgs boson can’t. So when experimenters look for the Higgs boson, they look over a range of masses and employ a variety of search strategies.

Q. What do we know about it so far?

A. Experimenters have already ruled out a large range of masses. The Higgs boson, if it exists, has to be heavier than 114.4 giga-electron volts (GeV), which are the units of mass that particle physicists use. By comparison, protons, the bedrock of ordinary matter, are about 1 giga-electron volt, and an electron is only half a million electron volts.

Based on recent searches by the L.H.C., the Higgs boson is also excluded between about 140 GeV and 500 GeV. This makes the most likely region for the Higgs mass to be between about 115 and 140 GeV, which is the range Tuesday’s results should focus on, although in principle heavier Higgs boson masses are in contention too.

I don’t want to shatter hopes, but don’t count on Tuesday’s results being definitive. This is the toughest range of masses for the L.H.C., and detection is tricky for this range. I suspect they will have enough evidence not to exclude the Higgs, but too little to fully pin it down without next year’s data.

Q. What difference does its mass make?

A. Actually, as far as matter’s properties go, it doesn’t really make a great deal of difference. As long as the Higgs mechanism is in place, elementary particles that we know about will have the masses that they do.

But no one thinks the Higgs is the final word about what underlies the Standard Model of particle physics, the theory that describes the most basic elements of matter and the forces through which they interact. Even if the Higgs boson is discovered, the question will still remain of why masses are what they are.

According to quantum field theory — the theory that combines quantum mechanics and special relativity — masses would be expected to be ten thousand trillion times bigger. Without some deeper ingredient, a fudge of that size would be required to make it all hang together. No particle physicist believes that.

We all expect a richer theory underlying the Standard Model. That’s one reason the mass matters to us. Some theories only accommodate a particular range of masses. Knowing the mass will give us insight into what that deeper underlying theory is.

Q. Is the L.H.C. a flop if we don’t find the Higgs boson?

A. The great irony is that not finding a Higgs boson would be spectacular from the point of view of particle physics, pointing to something more interesting than the simple Higgs model. Future investigations could reveal that the particle playing the role of the Higgs has interactions aside from the ones we know have to be there for particles to acquire mass.

The other possibility is that the answer is not the simple, fundamental particle that the Large Hadron Collider currently is looking for. It could be a more complicated object or part of a more complex sector that would take longer to find.

Q. Does this have anything to do with neutrinos — specifically, the ones that were recently reported as having traveled faster than light on a journey that originated at CERN?

A. Neutrinos have tiny masses. The Higgs mechanism is probably partially responsible for those, too. Just nothing that encourages them to go faster than light (which they most likely don’t).

Q. In 1993, the U.S. Congress canceled a larger American collider, the superconducting super collider, which would have been bigger than the CERN machine. Would it have found the Higgs particle years ago?

A. Yes, if it had gone according to schedule. And it would have been able to find things that weren’t a simple Higgs boson, too. The L.H.C. can do such searches as well, but with its lower energy the work is more challenging and will require more time.

Update:

GENEVA (AP) — One of two research teams hunting for an elusive sub-atomic
particle believed to be a basic building block of the universe announced Tuesday
that it has narrowed down the search thanks to the latest data.
The Higgs boson — also known as the so-called "God particle" — is more likely
to be found in the lower energy ranges of the massive atom smasher being used to
track it down, the team's leader said. The information is expected to be
confirmed later in the day by the second team.
The unveiling of the latest data has generated much buzz among researchers
who hope that the particle, if it exists, can help explain many mysteries of the
universe. British physicist Peter Higgs theorized the particle's existence more
than 40 years ago to explain why atoms, and everything else in the universe,
have weight.
Both of the research teams are involved with CERN, the European Organization
for Nuclear Research near Geneva. CERN oversees the $10-billion Large Hadron
Collider under the Swiss-French border, a 17-mile (27-kilometer) tunnel where
high energy beams of protons are sent crashing into each other at incredible
speeds.
Fabiola Gianotti, an Italian physicist who heads the team running what's
called the ATLAS experiment, said "the hottest region" is in lower energy ranges
of the collider. She said there are indications of the Higgs' existence and that
with enough data it could be unambiguously discovered or ruled out next
year.
Although it would be an enormous scientific breakthrough for the physics
world if the Higgs boson was found, officials at CERN have ruled out making any
such announcement this year.
Leaders of the second team, running what's called the CMS experiment, were
due to present their findings later Tuesday.