The Duck Pond Splash Down

Intrinsic properties are those that are fundamental to a particle itself, independent of external conditions. [Built-in]

Let’s categorize the properties into intrinsic properties and those used as identifiers:

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Intrinsic Properties

1. Mass – Fundamental to the particle.
2. Charge – Fundamental electromagnetic property.
3. Spin – An inherent form of angular momentum.
4. Colour Charge – Essential for quarks and gluons in strong interactions.
5. Parity – Describes symmetry properties, intrinsic to particles.

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Properties Used for Identification and Classification

1. Flavour – Used to differentiate types within a family (like quarks or leptons).
2. Lifetime – Indicates how long a particle exists before decaying, which is more about observing behaviour than an intrinsic characteristic.
3. Baryon Number – A conservation law used to identify types of particles like baryons.
4. Lepton Number – Similar to baryon number, it helps in classifying leptons.
5. Weak Isospin – Analogous to charge, but for weak interactions, serving more as a label for how particles interact under the weak force.

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Intrinsic properties such as mass, charge, spin, color charge, and parity are inherent qualities of the particles. Properties like flavour, baryon number, lepton number, weak isospin, and lifetime, while sometimes viewed as intrinsic, are often used more for identifying, classifying, and understanding interactions in particle physics.

We can ignore the non-intrinsic for now, but know that they are also applied to particles.

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Examples

The Photon

The photon, which is the quantum of electromagnetic radiation and the force carrier for the electromagnetic force, has the following intrinsic properties:

1. Mass: Photons are massless. They have zero rest mass, which allows them to travel at the speed of light in a vacuum.
2. Charge: Photons are electrically neutral, meaning they carry no charge.
3. Spin: Photons have a spin of 1. This intrinsic angular momentum is integral to their behaviour, particularly in how they interact with other particles through electromagnetic forces. However, because they are massless, their spin only manifests along their direction of motion (helicity), which can take the values of (+1).

These properties define the fundamental character of photons and govern their interactions and behaviours according to the rules of quantum mechanics and electromagnetism.

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Helicity

Helicity is a concept used in physics to describe the direction of spin of a particle in relation to its direction of motion. Think of it as measuring whether the particle’s spin is aligned with its movement or against it.

Imagine a particle as a tiny spinning ball.

If it moves in the direction it is spinning (like a right-handed screw moving forward as you twist it to the right), it has a positive helicity.

If it spins in the opposite direction of its movement (like a left-handed screw moving forward as you twist it to the left), it has negative helicity.

For massless particles like photons, which always move at the speed of light, helicity is especially meaningful because it’s always conserved (doesn’t change). Photons can have helicity (+1) or (-1), depending on their spin direction relative to their motion. This property is crucial for describing how light and other electromagnetic radiation interact with matter.

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Up Quark

Up quarks are one of the six types of quarks in the Standard Model of particle physics, and they have several intrinsic properties:

1. Mass: Up quarks have a mass of approximately 2.3 MeV/c². However, this value can vary depending on the energy scale due to quantum chromodynamics effects.
2. Charge: Up quarks carry an electric charge of (+2/3) elementary charges.
3. Spin: Like all quarks, up quarks have a spin of (1/2), which makes them fermions. This half-integer spin means they obey Fermi-Dirac statistics.
4. Color Charge: Up quarks possess a color charge, an intrinsic property necessary for participating in strong interactions. This color charge can be one of three types: red, green, or blue.

These properties not only define the up quark but also dictate how it interacts with other fundamental particles through the fundamental forces of nature.

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The table

For me, this table gives a list of observed properties of particles that helps with understanding. It is simple and easy to grasp. However, we will dive into each of the properties in further posts.

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