Why higgs mechanism

Nobel Prize announcement with accompanying background. Focus story on Nobel Prize for theory of symmetry breaking.

A new technique in which atoms move slowly through a diffraction grating lets researchers measure the tiny Casimir-Polder interaction, a force that arises from quantum vacuum fluctuations. Read More ». The Nobel Prize in Physics has been awarded to two of the theorists who formulated the Higgs mechanism, which gives mass to fundamental particles.

Higgs Phys. Englert and R. Brout Phys. The analogy you used is very helpful. I like the fact that this is independent of thinking about photons or just energy transfer and that the interaction of a field does the job without implying friction and the nonsense that arises from it.

Your fog analogy is very similar to this, and I concede, maybe more straightforward than mine with an audience that does not want to go into the sun energy transfer.

In any case, yes, this interaction kind of stuff fog or photon extinction is the best approach by far. Fernando, thanks for the awesome analogy post. Yes, I find it amazing how photons that impact Earth are hundred of thousands years old. It just raises more questions! Just as Sean roughly mentioned in his book, we are wired up to ask questions. Human nature. I would hate to be born without asking questions about how anything works.

Look to the stars! Saw your talk tonight. Second, thanks for differentiating here and in your book between mass wrt elementary particles versus ordinary objects. Sean and the other guests were very interesting and did a great job with providing info on the Higgs and the LHC.

I am a great admirer of your work and I would like very much to join your blog. At present I am reading your new book on Higgs. Without the Higgs mechanism, all particles are not allowed to have a mass, because such terms would violate the gauge symmetry. Breaking of gauge symmetry is a bad thing, because the renormalizability , i. However, we know from experiments that some elementary particles , like the electron or also the W-bosons that mediate weak interactions, are massive.

These masses can be explained thanks to the Higgs mechanism. The masses then arise as a result of the coupling of the massive particles to the Higgs field and this is possible without breaking gauge symmetry. The Higgs mechanism is no longer just a theory but was confirmed by the discovery of the Higgs particle through the LHC experiment.

One sure priority is the research program in Higgs physics. The discovery of the Higgs boson [7] opened the door to the understanding of the mechanism of electroweak breaking. This mechanism plays a crucial role in nature, giving rise to a fundamental scale that rules not only the microscopic world but many physical properties of our universe, from the size of atoms to the timescale of the processes that make the sun shine.

Missing the opportunity to study in depth the mechanism of electroweak breaking would be like giving up the exploration of a new continent in the planet of knowledge.

Although a fundamental milestone, the discovery of the Higgs cannot be regarded as the final resolution to the enigma of electroweak breaking. If anything, its discovery has rendered unavoidable the need to address some of the open problems in particle physics. Indeed, every single Higgs interaction introduces its own puzzle. The Yukawa couplings express the flavour problem, i. The Higgs quartic coupling raises issues with the stability of the SM electroweak vacuum.

The Higgs quadratic term incarnates the naturalness problem. The constant term in the Higgs potential is an expression of the cosmological constant problem. The root of these problems is that the Higgs boson introduces 14 new forces without taking into account other forces associated with neutrinos besides the 3 known fundamental forces of the Standard Model.

Unlike strong, weak, and electromagnetic forces, these new 14 forces are not gauge-like. Not surprisingly, they do not share the properties of elegance, simplicity, robustness, and predictivity that characterise the gauge forces of the Standard Model. Accustomed with the conceptual perfection of the gauge sector of the Standard Model, it is difficult for a theorist to believe that a structure so arbitrary and provisional as the Higgs sector could be the final word on electroweak breaking.

There must be more still to be discovered. The way to get to the bottom of the question is a program of precision measurements on the Higgs boson properties. This is already underway, but future high-energy colliders will be able to bring these precision studies to unprecedented levels of precision.

Much can be learned from these studies about the Higgs boson, the phenomenon of electroweak breaking, the fundamental laws that govern nature, the early stages of the Universe and its ultimate fate. But is the gauge symmetry actually broken spontaneously? In the above exposition of the Higgs mechanism, there were two instances when a symmetry was broken.

First, when we selected one minimum out of the infinite number of equivalent minima, a spontaneous breaking indeed took place, but only of a global symmetry. This minimum represents a vacuum, and in order to perturbatively describe the quantum field theory, we need to quantize the fields. Quantization of gauge field theories requires the introduction of a gauge-fixing procedure, and during this procedure, we break the gauge symmetry by hand, explicitly, not spontaneously.

The reason why the phase with nonvanishing scalar expectation value is often labeled SSB is that one uses perturbation theory to select at zero coupling with the gauge fields a scalar field configuration from global SSB; but this preferred choice is only a convenient one. Symmetry breaking in QFT results from a mismatch between variational symmetries of the Lagrangian and symmetries that can be implemented as unitary transformations on the Hilbert space of states.

The second case corresponds to SSB. The symmetry is hidden in that there is no unitary operator to map a physical state to its symmetric counterparts; instead, the symmetry is roughly speaking a map from one Hilbert space of states to an entirely distinct space.

Similarly, in QFT, the degenerate vacua correspond to distinct global field configurations with minimum energy, with Hilbert spaces built up from a particular vacuum state. Associated with spontaneous symmetry breaking is the phenomenon of symmetry restoration. If one heats a system that possesses a broken symmetry it tends to be restored at high temperature. Thus a ferromagnetic material can be magnetized at low temperature or even at room temperature with all the little atomic magnets aligned in the same direction.

This is a state of broken rotational symmetry. As the temperature increases the atoms vibrate more and more. Finally when the temperature is greater than a certain critical value the fluctuations win out over the forces that tend to align the atomic magnets and the average magnetization vanishes. Above the critical temperature the system exhibits rotational symmetry. Such a transition from a state of broken symmetry to one where the symmetry is restored is a phase transition.

We believe that the same phenomenon occurs in the case of the symmetries of the fundamental forces of nature. Many of these are broken at low temperatures. Very early in the history of the universe, when the temperature was very high, all of these symmetries of nature were presumably restored. The resulting phase transitions, as the universe expanded and cooled, from symmetric states to those of broken symmetry have important cosmological implications.

The role of symmetry in fundamental physics by David J. The Higgs sector of the Standard Model of particle physics represents a 4d Yukawa model. A careful analysis of this sector reveals that it defines a trivial theory. The cutoff has to be introduced to regularize the theory. Thus the Higgs sector of the Standard Model can only be considered as an effective theory connected with a non-removable cutoff parameter, which can be interpreted as the maximal scale up to which the underlying effective theory can be trusted.

This remarkable fact tells us that once the Higgs boson has been discovered and its physical mass mH measured, it would be possible to infer the scale up to which the Standard Model can be valid at most from the comparison of mH with its cutoff-dependent upper bound.

They obtained reliable upper and lower bounds on the Higgs boson mass as a function of the cutoff parameter [44, 45].

On the other hand, for a Higgs boson mass of about GeV the Standard Model can be valid up to very large cutoff scales.

Nair at page It should be emphasized that there is no breakdown of this true gauge symmetry here. In fact gauge symmetry is crucial in removing the massless modes. To show how this works out in some detail, we will…. This breaking of a global symmetry is also mentioned at page in Duncan's "Conceptual Framework of Quantum Field Theory":.

Once a gauge is fixed, however, to remove the redundant degrees of freedom, the remaining discrete! RSS - Posts. Skip to content. Or Just an Important One?

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Higgs Discovery: Is it a Simplest Higgs? Is it a Higgs? Perhaps Composite? A Higgs of Simplest Type? More Than One Higgs? The Higgs FAQ 2. Movie Clips New? Share this: Twitter Facebook. Like this: Like Loading Jay carlson July 2, at PM Reply. Joey July 2, at PM Reply.

Giovanni July 3, at PM Reply. Dan July 3, at PM Reply. Nice piece. Mike July 4, at AM Reply. Alex July 4, at AM Reply. Thank you! Cannot express how much I appreciate your postsx. Pooja July 4, at AM Reply. This is most definitely a forum for curious laypeople! Mike July 4, at PM Reply. Mathematician July 6, at AM Reply. Mathematician July 7, at AM Reply.

Will do Matt! Hope to hear you give some talks and looking forward to your book! Jo July 10, at AM Reply. Sammy July 10, at PM Reply. Particle matters July 16, at PM Reply.

Thanks — well explained on a difficult subject — Matty Particle Matters. Veronica June 22, at PM Reply. I know this is entirely off topic buut I had to share it with someone! Good info. Lucky me I found your site by accident stumbleupon. I seriously appreciate individuals like you! Take care!! Brandi March 6, at PM Reply. Leave a Reply Cancel reply Enter your comment here Fill in your details below or click an icon to log in:.