Particle Physics and the Universe

Particle Physics of the Early Universe

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But the Higgs' field has two very important jobs to do that can't be achieved by any other field. Its first job is to talk to the W and Z bosons via their respective fields , the carriers of the weak nuclear force. By talking to these other bosons, the Higgs is able to give them mass and make sure that they stay separated from the photons, the carriers of electromagnetic force.

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Without the Higgs boson running interference, all these carriers would be merged together and those two forces would merge together. The other job of the Higgs boson is to talk to other particles, like electrons; through these conversations, it also gives them mass. This all works out nicely, because we have no other way of explaining the masses of these particles. This was all worked out in the s through a series of complicated but assuredly elegant math , but there's just one tiny hitch to the theory: There's no real way to predict the exact mass of the Higgs boson.

In other words, when you go looking for the particle which is the little local vibration of the much larger field in a particle collider, you don't know exactly what and where you're going to find it.

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In , scientists at the LHC announced the discovery of the Higgs boson after finding a few of the particles that represent the Higgs' field had been produced when protons were smashed into one another at near light-speed. These particles had a mass of gigaelectronvolts GeV , or about the equivalent of protons — so it's kind of heavy but not incredibly huge. At first glance, all that sounds fine.

Physicists didn't really have a firm prediction for the mass of the Higgs boson, so it could be whatever it wanted to be; we happened to find the mass within the energy range of the LHC. Break out the bubbly, and let's start celebrating.

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Except that there are some hesitant, kind-of-sort-of half-predictions about the mass of the Higgs boson based on the way it interacts with yet another particle, the top quark. Those calculations predict a number way higher than GeV. It could just be that those predictions are wrong, but then we have to circle back to the math and figure out where things are going haywire. Or the mismatch between broad predictions and the reality of what was found inside the LHC could mean that there's more to the Higgs boson story. There very well could be a whole plethora of Higgs bosons out there that are too heavy for us to see with our current generation of particle colliders.

The higher a particle's mass, the more energy it has and the more energy it takes to create that hefty thing. In fact, some speculative theories that push our knowledge of physics beyond the Standard Model do predict the existence of these heavy Higgs bosons. The exact nature of these additional Higgs characters depends on the theory, of course, ranging anywhere from simply one or two extra-heavy Higgs fields to even composite structures made of multiple different kinds of Higgs bosons stuck together. Theorists are hard at work trying to find any possible way to test these theories, since most of them are simply inaccessible to current experiments.

In a recent paper submitted to the Journal of High Energy Physics, and published online in the preprint journal arXiv , a team of physicists has advanced a proposal to search for the existence of more Higgs bosons, based on the peculiar way the particles might decay into lighter, more easily-recognizable particles, such as electrons, neutrinos and photons.

Physicists Search for Monstrous Higgs Particle. It Could Seal the Fate of the Universe.

However, in the past two decades, a new branch of string theory called F-theory has allowed physicists to work with strongly interacting, or strongly coupled, strings. This means that string theorists can use algebraic geometry—which uses algebraic techniques to tackle geometric problems—to analyze the various ways of compactifying extra dimensions in F-theory and to find solutions.

Mathematicians have been independently studying some of the geometric forms that appear in F-theory. Now, Cvetic, Lin, James Halverson of Northeastern University in Boston, and their colleagues have used such techniques to identify a class of solutions with string vibrational modes that lead to a similar spectrum of fermions or, particles of matter as is described by the standard model—including the property that all fermions come in three generations for example, the electron, muon and tau are the three generations of one type of fermion.

For example, the quarks and leptons in these solutions come in left and right-handed versions, as they do in our universe.

The new work shows that there are at least a quadrillion solutions in which particles have the same chiral spectrum as the standard model, which is 10 orders of magnitude more solutions than had been found within string theory until now. Further study would involve uncovering stronger connections with the particle physics of the real world. The researchers still have to work out the couplings or interactions between particles in the F-theory solutions—which again depend on the geometric details of the compactifications of the extra dimensions.

It could be that within the space of the quadrillion solutions, there are some with couplings that could cause the proton to decay within observable timescales.

This would clearly be at odds with the real world, as experiments have yet to see any sign of protons decaying. Alternatively, physicists could search for solutions that realize the spectrum of standard model particles that preserve a mathematical symmetry called R-parity. Also, the work assumes supersymmetry, which means that all the standard model particles have partner particles.

String theory needs this symmetry in order to ensure the mathematical consistency of solutions. Crucially, experiments at the Large Hadron Collider LHC have also shown that supersymmetry—if it is the correct description of nature—is not broken even at the energy scales probed by the LHC, given that the LHC has yet to find any supersymmetric particles.

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String theorists think that supersymmetry might be broken only at extremely high energies that are not within experimental reach anytime soon. Despite these caveats, other string theorists are approving of the new work. It works out nicely here. But Vafa and Taylor both caution that these solutions are far from matching perfectly with the standard model.

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