Original URL: http://www.theregister.co.uk/2010/06/15/higgs_bosons/

God particles breeding like bosons

Family of Higgs actually five, US research suggests

By Lester Haines

Posted in Science, 15th June 2010 08:30 GMT

US researchers have suggested that the elusive God particle - the Higgs boson - may actually be no less than a quintet of divine, and as yet elusive, components of the universe.

The Standard Model. Source: AAASThe theoretical Higgs boson is required to give mass to the 16 other particles described by the Standard Model (see graphic), the "internally consistent" theory describing the electromagnetic, strong nuclear and weak nuclear interaction between particles.

New findings from the DZero experiment at Fermilab's Tevatron particle accelerator, however, have led scientists to propose five such particles.

DZero is looking into just why the universe has more matter than antimatter - the so-called "CP violation" of the principle of "CP symmetry", which states that the sum of two symmetries - charge conjugation (C), which transforms a particle into its antiparticle, and parity (P) - should result in an equal amount of matter and antimatter.

Fermilab summarises: "When matter and anti-matter particles collide in high-energy collisions, they turn into energy and produce new particles and antiparticles.

"Similar processes occurring at the beginning of the universe should have left us with a universe with equal amounts of matter and anti-matter. But the world around is made of matter only and antiparticles can only be produced at colliders, in nuclear reactions or cosmic rays."

CP violation, which could go some way to explaining the disappearing antimatter mystery, was first demonstrated back in 1964 by James Cronin and Val Fitch in the decay of neutral kaons ("strange" particles containing strange quarks). DZero has focused on demonstrating the result of high-speed collisions of protons and anti-protons, yielding pairs of muon and antimuon particles from the decay of B mesons.

The result is a one per cent difference in the production of muons and antimuons, which represents a much greater matter/anti-matter ratio than previously seen.

This disparity is "beyond what could be explained by the Standard Model", the BBC explains, so enter stage left multiple Higgs bosons.

Fermilab's Bogdan Dobrescu, Patrick J Fox and Adam Martin say the findings indicate "five Higgs bosons with similar masses but different electric charges".

The BBC elaborates that according to this "two-Higgs doublet model", three bosons would have a neutral charge and "one each would have a negative and positive electric charge".

The name of this theoretical concept comes from the fact that while under the Standard Model the Higgs boson is seen as one particle, it actually comes in a "package of four". Martin explained to the BBC: "In the Standard Model, you only see one of them because the other three are absorbed into [other parts of the scheme] such as the W and the Z bosons. There's only one left.

"So if you want to add another Higgs doublet - you actually have to add four more particles."

If that's not enough particles for you, the Fermilab team's suggestion also fits into the "supersymmetry" theory, which is "an extension to the Standard Model, in which each particle in the scheme has a more massive 'shadow' partner particle".

Just how many Higgs bosons there actually are, and whether the universe is really full of supersymmetrical shadowy partners could be revealed by in due course by the Large Hadron Collider.

The Fermilab press release is here, and its "Evidence for an anomalous like-sign dimuon charge asymmetry" is here. ®