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Define the concept of baryon number
Define the concept of baryon number
Baryon number is defined as a quantum number of a system defined by B=1/3*(number of quarks - number of anti-quarks).
Define the concept of lepton number
Define the concept of lepton number
Lepton number is defined as a conserved quantum number representing the difference between the number of leptons and the number of antileptons in an elementary particle interaction, defined by L=(number of leptons - number of antileptons).
Recall conservation
Recall conservation
Baryon number and lepton number are always conserved in a reaction. Baryon and lepton number are the same before and after an interactions, therefore are conserved.
Explain electron and electron particle interaction
Explain electron and electron particle interaction
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Explain electron positron particle interaction
Explain electron positron particle interaction
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Explain electron and positron annihilation particle interaction
Explain electron and positron annihilation particle interaction
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Explain a neutron decaying intro a proton particle interaction
Explain a neutron decaying intro a proton particle interaction
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Study Notes
Baryon Number
- A quantum number representing the total number of baryons in a system.
- Baryons are particles like protons and neutrons, which have a baryon number of +1.
- Antibaryons, such as anti-protons, have a baryon number of -1.
- Non-baryonic particles, like electrons and neutrinos, have a baryon number of 0.
- Baryon number is conserved in all particle interactions, meaning the total baryon number before and after a reaction remains constant.
Lepton Number
- A quantum number that signifies the total number of leptons in a system.
- Leptons include particles like electrons, muons, and neutrinos, each with a lepton number of +1.
- Antileptons, such as positrons and antineutrinos, have a lepton number of -1.
- Non-leptonic particles do not contribute to the lepton number, having a value of 0.
- Lepton number is also conserved in particle interactions, maintaining the total lepton number pre and post-reaction.
Conservation
- Both baryon number and lepton number are fundamental conservation laws in particle physics.
- These conservation laws apply during particle decay, annihilation, and other reactions, ensuring that these quantum numbers do not change overall in an isolated system.
Electron and Electron Interaction
- Electrons are negatively charged leptons that participate in electromagnetic interactions.
- They can scatter off each other primarily through the exchange of virtual photons.
- Such interactions are governed by electromagnetic force and can result in changes in direction but preserve energy and momentum.
Electron-Positron Interaction
- An electron (e-) and a positron (e+), being matter and antimatter counterparts, interact through electromagnetic forces.
- When they come close, they can annihilate each other, a significant interaction resulting in photon creation.
- This interaction can produce energy according to the mass-energy equivalence principle (E=mc^2).
Electron-Positron Annihilation
- Annihilation of an electron and a positron results in the production of gamma-ray photons.
- Typically produces two photons moving in opposite directions due to conservation of momentum.
- This process is a direct demonstration of the relationship between mass and energy, as the mass of the electron and positron is converted to energy in the form of photons.
Neutron Decay into Proton
- A neutron can decay into a proton through a process called beta decay.
- During this interaction, a neutron (n) transforms into a proton (p) by emitting a W- boson, which subsequently decays into an electron and an electron antineutrino.
- This conversion preserves baryon number (no change, as both neutron and proton are baryons) and the lepton number (initially 0, ending with +1 from electron and -1 from antineutrino).
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Description
This quiz explores the fundamental concept of baryon number in particle physics. It aims to clarify how baryon number conservation plays a significant role in understanding nuclear reactions and interactions. Perfect for students who want to deepen their knowledge of subatomic particles.
