Higgs Boson

FIELDS OF STUDY: Quantum Field Theory; Atomic Physics; Quantum Physics

ABSTRACT: This essay describes the discovery and importance of the Higgs boson. The Higgs boson is the elementary particle that accounts for gravitation in the standard model of physics. The existence of such a particle was first proposed by Dr. Peter Higgs in 1964. The existence of the particle was proven in 2013 through work performed at CERN (the European Organization for Nuclear Research).

principal terms

• boson: carrier of one of the four fundamental forces.
• electroweak force: the force responsible for nuclear decay.
• elementary particle: one of the fundamental constituents of matter.
• Higgs field: a theorized field that, through interactions with matter, causes that matter to have mass.
• lepton: an elementary particle that has no color and thus cannot form nuclei.
• standard model: the contemporary framework for understanding particle physics.

Elementary Particles

The standard model of particle physics is the primary theoretical model used to explain and predict particle interaction at the smallest scales and to describe the known subatomic particles. It has limitations, notably not working well with the full theory of gravitation as laid out in general relativity, but in its domain, it has been hugely successful.

At the subatomic level, everything is made of the elementary particles. The Higgs boson is the first step in reconciling gravitation and particle physics. The interactions between these particles are mediated by the fundamental forces, which are interactions among a set of distinct properties. These forces are electromagnetism, the strong nuclear force, the weak nuclear force, and gravity.

Electromagnetism is the force that causes things with opposite charges (positive and negative) to attract each other, while things with the same charge repel each other. This can easily be observed with magnets. On the atomic level, electromagnetism is also responsible for many other phenomena, such as friction. Electromagnetism is also what binds atoms together into molecules. This force is carried by the photon, which is also the particle responsible for light. A particle that carries a force is a boson and interacts with only that one force.

The strong nuclear force is the force that sticks quarks together into more complex units like protons and neutrons. Strong nuclear force is linked to the property of color, which has nothing to do with visible color, but instead, is a way of tracking the property metaphorically. Color is said to come in three primary types (red, blue, and green), each with an opposite (antired, antiblue, and antigreen). When the three types are combined in a stable way, they cancel out in a way similar to that in which red, blue, and green light combine to make white in a human eye. The strong nuclear force is transmitted in bosons called gluons, so called because they glue things together. It has color but no charge or mass, similar to the way in which a photon has charge but no mass or color. The reason it is called the strong nuclear force is that the attraction between differently color-charged quarks within protons is what holds the nuclei of atoms together. The attraction of the strong force is enough to overcome the electromagnetic repulsion between the protons.

The weak nuclear force changes the flavor of quarks. There are six flavors of quarks: up, down, strange, charm, top, and bottom. Each flavor of quark has a different charge, mass, and spin. If one can change the flavor, one can change those things. Weak nuclear force is carried by W and Z bosons. These bosons have mass, although bosons are not supposed to. This breaks electroweak symmetry. In physics, a symmetry is an unchanging mathematical or physical property that is necessary for a system, such as the general model, to function. Although the fuss over symmetry-breaking sounds like nitpicking and overreliance on theory, symmetries are the guiding principles of particle physics and are deeply ingrained in the math that guides the research. Electromagnetism is usually treated in concert with the weak nuclear force as electroweak force. This is because they have essentially equal strength.

Leptons are particles that do not have color and thus do not experience the strong force. They do not bond in nuclei. Quarks can be thought of as pack animals, like dogs, usually found in groups, while leptons are solitary, like cats. Electrons are the best-known kind of lepton.

The fundamental forces can be conceived of as being stored in a field, with bosons manifesting from the field to interact with other particles. A field suffuses space and gives it that property.

The Gravitational Outlier

The last fundamental force is gravity, which is observable on the largest scales and has the longest range. It has long been puzzling how gravity works, since general relativity does not mesh well with quantum mechanics. Scientists have also wondered why W and Z bosons have mass. As bosons, they should be interacting with only one force. This discrepancy led to theorizing that there could be certain conditions where the symmetries do not apply. Because gravity happens everywhere, the field responsible for it must exist everywhere. This theoretical field was dubbed the Higgs field, after the physicist Peter Higgs, one of the scientists who proposed it in 1964. The Higgs field breaks the symmetry of the electroweak interaction.

In theorizing this, they later realized that this would also explain why other fundamental particles had mass. The Higgs boson would thus be an excitation from the underlying and pervading Higgs field that would then interact with different particles in the same way that the other bosons do to give them greater or lesser mass. The theory provided a plausible explanation of the observable conditions, but there was no proof at first. Equally, it required assuming the existence of scalar fields. Up to this point, fields had been described as vector, meaning that they have a strength and direction, polarity, flavor, and color. A scalar field has only the strength. The issue was proving it.

Finding the Higgs Boson

Higgs bosons are very short-lived and require high-energy states to be observed. In order to find the Higgs boson, a new generation of technology was needed. Because these particles are so short-lived, the most effective way to find them was to search for the products of their decay. To create them, more powerful colliders were required. Colliders work by slamming particles together at very high energies. The higher energy the collision, the more interesting things scatter. It is akin to trying to learn about how a car works by ramming it into a wall and seeing what parts come flying out. Though scientists might theorize that spark plugs existed, in order to obtain proof, they would need a crash powerful enough to break the engine block open and a net fine enough to catch something as small as the plug.

This sort of collision required energy orders of magnitude beyond what the colliders of the 1960s could generate. To that end, it took the construction of CERN’s Large Hadron Collider (LHC) to generate the power and provide the detectors, and the invention of a massive data sharing and computing space across the range of international researchers. Likewise, in order to sift the data, distributed computing systems were devised to allow calculations to be spread out over many computers, an early example of cloud computing.

Scientists found evidence of a particle that had the properties of the Higgs boson and appeared in the proper places on July 4, 2012. This suggested that the Higgs theory was correct, but while it was clear that a new boson had been discovered, it was unclear if that boson was the Higgs boson. As more data emerged, scientists found more and more proof that this particle was indeed the Higgs boson. On March 14, 2013, it was tentatively confirmed as the Higgs boson, though there may be multiple Higgs bosons. A second run of the LHC, upgraded for greater collision energy, was completed in 2015; further exploring the properties of the Higgs boson was one of CERN’s main goals for the upgraded LHC.

As scientists continued to study the data from the LHC, it was announced in the fall of 2017 that some teams had been working on programming a quantum computer to be able to sift through large amounts of such data and assist in the discovery of new particles. To develop this technology, the scientists tested to see if a quantum computer could detect the Higgs boson; while the experiment was a success in that it proved that it would be possible, the scientists noted that they have yet to determine whether this method would be most efficient.

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