Francois Englert and Peter Higgs

Colloquium on the 2013 Nobel Prize in Physics Awarded to Francois Englert and Peter Higgs

Philip D. Mannheim

In 2013 the Nobel Prize in Physics was awarded to Francois Englert and Peter Higgs for their development in 1964 of the mass generation mechanism (the Higgs mechanism) in local gauge theories.
This mechanism requires the existence of a massive scalar particle, the Higgs boson, and in 2012 the Higgs boson was finally observed at the Large Hadron Collider after an almost half a century search. In this talk we review the work of these Nobel recipients and discuss its implications.

Search for Higgs shifts in white dwarfs

The discovery of the Higgs boson at the Large Hadron Collider (LHC) in 2012 marked an important step toward understanding the origin of the mass of fundamental particles. Since mass plays a major role in gravity, the Higgs could also reveal insights into the nature of gravity. One possibility is that the Higgs field could couple to a specific spacetime curvature, a scenario that is invoked in various extensions of the standard model.

Now, scientists have shown that dying stars called white dwarfs can be used to investigate and place limits on the coupling between the Higgs field and spacetime curvature. The study, by Roberto Onofrio at the University of Padova in Italy and the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and Gary A. Wegner at Dartmouth College in Hanover, New Hampshire, is published in a recent issue of The Astrophysical Journal. Continue reading Search for Higgs shifts in white dwarfs

Mother of Higgs boson found in superconductors

A weird theoretical cousin of the Higgs boson, one that inspired the decades-long hunt for the elusive particle, has been properly observed for the first time. The discovery bookends one of the most exciting eras in modern physics.

The Higgs field, which gives rise to its namesake boson, is credited with giving other particles mass by slowing their movement through the vacuum of space. First proposed in the 1960s, the particle finally appeared at the Large Hadron Collider at CERN near Geneva, Switzerland, in 2012, and some of the theorists behind it received the 2013 Nobel prize in physics.

But the idea was actually borrowed from the behaviour of photons in superconductors, metals that, when cooled to very low temperatures, allow electrons to move without resistance.

Near zero degrees kelvin, vibrations are set up in the superconducting material that slow down pairs of photons travelling through, making light act as though it has a mass.

This effect is closely linked to the idea of the Higgs – “the mother of it actually,” says Raymond Volkas at the University of Melbourne in Australia.

Those vibrations are the mathematical equivalent of Higgs particles, says Ryo Shimano at the University of Tokyo, who led the team that made the new discovery. The superconductor version explains the virtual mass of light in a superconductor, while the particle physics Higgs field explains the mass of W and Z bosons in the vacuum.

Double trouble

Physicists had expected the Higgs-like effect to appear in all superconductors because it is also responsible for their characteristic property – zero electrical resistance. But it had only been seen before by imposing a different kind of vibration on the material.

To find it in a superconductor in its normal state, Shimano and colleagues violently shook the superconductor with a very brief pulse of light. Shimano says it is similar to how particle physicists create the real Higgs boson with energetic particle collisions. They first created the superconducting Higgs last year, and have now studied its properties to show that, mathematically speaking, it behaves almost exactly like the particle physics Higgs.

Noting the similarities between the two systems could be useful in studying the real Higgs boson. “One can prepare various types of ‘vacuum’ in condensed matter systems, which are not able to be realized in particle physics experiments,” Shimano says. “One can really do the experiments in a table-top manner, which would definitely reveal new physics and hopefully provide some useful feedbacks to particle physics.”

Journal reference: Science, DOI: 10.1126/science.1254697

by Michael Slezak –

Evidence for the direct decay of the 125 GeV Higgs boson to fermions

The CMS Collaboration
The discovery of a new boson with a mass of approximately 125 GeV in 2012 at the Large Hadron Collider has heralded a new era in understanding the nature of electroweak symmetry breaking and possibly completing the standard model of particle physics.
Since the first observation in decays to γγ, WW and ZZ boson pairs, an extensive set of measurements of the mass and couplings to W and Z bosons, as well as multiple tests of the spin-parity quantum numbers, have revealed that the properties of the new boson are consistent with those of the long-sought agent responsible for electroweak symmetry breaking.
An important open question is whether the new particle also couples to fermions, and in particular to down-type fermions, as the current measurements mainly constrain the couplings to the up-type top quark.
Determination of the couplings to down-type fermions requires direct measurement of the corresponding Higgs boson decays, as recently reported by the Compact Muon Solenoid (CMS) experiment in the study of Higgs decays to bottom quarks15 and τ leptons.
Here, we report the combination of these two channels, which results in strong evidence for the direct coupling of the 125 GeV Higgs boson to down-type fermions, with an observed significance of 3.8 standard deviations, when 4.4 are expected….
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The Higgs boson and the neutrino

Massive thoughts
The Higgs boson and the neutrino fascinate the general public and particle physicists alike. Why is that?

Nigel Lockyer, Director of Fermilab

If there are two particles that everyone has read about in the news lately, it’s the Higgs boson and the neutrino. Why do we continue to be fascinated by these two particles?

As just about everyone now knows, the Higgs boson is integrally connected to the field that gives particles their mass. But the excitement of this discovery isn’t over; now we need to figure out how this actually works and whether it explains everything about how particles get their mass. With time, this knowledge is likely to affect daily life.

One way it could possibly bridge the gap between fundamental research and the commercial market, I believe, is in batteries. The ultimate battery in nature is mass. The expression E=mc2 is a statement of that fact. During the early moments of the universe, all particles were massless and traveling at the speed of light. Once the Higgs mechanism turned on, particles suddenly began interacting with the field and, in this process, converted their energy into what we now refer to as mass. In a recent address to the Canadian Nuclear Society, I suggested that if engineers of the future could learn how to manipulate the Higgs field (to “turn it on and off”), then we would have developed the ultimate energy source and the best battery nature has created. This idea definitely belongs in the science-fiction category, but remember that progress in science is driven by thinking “outside the box!”

This sort of thinking comes from looking at the Higgs from another angle. According to the Standard Model, many particles come in left-handed and right-handed versions (in the former, the particle’s direction of spin matches its direction of motion, while in the latter, they are opposite).

Keeping this fact in mind, let’s look at the mass of the familiar electron as an example. When we say that the mass of the electron is created by interactions with the Higgs field, we can think of this as the Higgs field rapidly changing a left-handed electron into a right-handed electron, and vice versa. This switching back and forth is energy and, through E=mc2, energy is mass. A heavier particle like the top quark would experience this flipping at a much higher frequency than a lighter particle like the electron. As we learn more about how this process works, I encourage physicists to also seek applications of that knowledge.

And what about neutrinos? Do they get their mass from the Higgs field or in a completely different way? Once thought to be massless, neutrinos are now known to have a tiny mass. If the Higgs mechanism is responsible for that mass, there must exist both a left-handed and a right-handed neutrino. A good number of physicists think that both are out there, but we do not yet know. That knowledge may help us understand why the neutrino mass is tiny, as well as why there is more matter than antimatter in the universe—one of the most important questions facing our field of particle physics.

But since the neutrino is a neutral particle, the story gets more interesting. It may instead be possible that there is another type of mass. Referred to as a Majorana mass, it is not a mass described by the flipping of left- and right-handed neutrinos back and forth, but it is “intrinsic,” not derived from any kind of “motional energy.” I expect that the efforts by our field of particle physics, in the collective sense, will pursue the questions associated with both the Higgs boson and the neutrino with enthusiasm, and that the results will lead to advancements we can’t even imagine today.

Nobel laureate François Englert at CERN last week. The equation on the blackboard describes the Brout-Englert-Higgs mechanism that gives particles mass (Image: Maximilien Brice)

François Englert, The formula of the universe

Nobel laureate François Englert at CERN last week. The equation on the blackboard describes the Brout-Englert-Higgs mechanism that gives particles mass (Image: Maximilien Brice)

Nobel laureate François Englert at CERN last week. The equation on the blackboard describes the Brout-Englert-Higgs mechanism that gives particles mass (Image: Maximilien Brice)

A Nobel laureate and a blackboard at CERN is all you need to explain the fundamental physics of the universe. At least, that’s what François Englert convinced us on his visit to CERN last week.
Englert shared the 2013 Nobel prize in physics with Peter Higgs “for the theoretical discovery of a mechanism that contributes to our understanding of the origin of mass of subatomic particles”. In the video below, he explains how he and Higgs manipulated equations containing mathematical constructs called scalar fields to predict the existence of the Brout-Englert-Higgs field.

Nobel laureate François Englert explains the Brout-Englert-Higgs mechanism that gives particles mass, with the help of a blackboard (Video: CERN)

According to Englert, the equation describing this mechanism is built in two parts. One part consists of scalar fields; the other consists of constructs called gauge fields. Englert explains that a big problem in particle physics in the 1960s was to find a gauge field that had mass. Solving that problem – working out how a gauge field could have mass -would help to explain other problems in physics, such as how to mathematically describe short-range interactions inside the nuclei of atoms. But Englert says that you cannot easily just add mass to a gauge field “off-hand”. He needed another theoretical approach.
The key was to add a new part – a new scalar field – to the equation describing the mass mechanism. Part of this new scalar field could be mathematically simplified. What came out of the algebraic manipulation was a term that gave rise to “a condensate spread out all over the universe”. Then, the interaction between the condensate and another part of the equation could be generalized, says Englert, to give mass to elementary particles. Easy peasy!
“I know this is extremely abstract,” says a modest Englert of his explanation. “But if I have two minutes [to explain it], I can hardly do more!”