# Homework Help: Sub-atomic particles

1. Jul 29, 2010

### bharata

Hi all I'm new here and this is my first post. Sorry if it's a bit weird...
So I have an investigation and here is the task...

Baryons, leptopns, mesons - strange names for strange particles
Select any family of sub-atomic particles, research its discovery, and write a report that highlights the physical nature of the particle family. Remember that this is a physics report and ensure that the physics ideas are given appropriate importance.

Now, my question first of all is, what is sub-atomic particles. I think sub-particles are the particles that are smaller than an atom. But I need more detail on this and please help me give examples of sub-particles. And what it means by "family" of sub-atomic. Like why does the word "family" indicate for?

Also as a beginner in physics(I am now in year 12), would you advice me of the things I should write in my report? Because I understand that you know what sort of things a teacher would expect with the task above. (i.e I shouldn't go too detail on certain parts and I should be more precise on certain parts)

This task is due on Monday and I would like any of your help :)
Thank you

2. Jul 29, 2010

### merryjman

You are correct: sub-atomic particles are those which are smaller than an atom. Some of them belong to a family called "baryons," of which the neutron and the proton are 2 of many examples. They are called this because they're made of 3 "quarks" rather than 2 (those are called "mesons"). Baryons and mesons are classes of particles called "hadrons" which basically means particles made from quarks. And there are 18 known varieties of quark.

Others belong to a family called "leptons," of which the electron, neutrino and muon are examples.

That is what is meant by the word "family."

A good introductory-level website where you can learn a lot about this stuff is http://www.particleadventure.org/ Click "GO!" where it says "Standard Model" and read all the way through it, and you'll understand why there are so many names and so many families.

3. Jul 30, 2010

### bharata

hey thanks, the website helps a lot and tell me anything I would need to know.
Now I'm going to start my writing and I think 'leptons' would be my choice, since the web you gave contained more precise information about leptons.
Do you know what sort of things I could write for family 'leptons' considering the task is asking 'the discovery' and 'physics idea', etc.

I am afraid I write things that are not important to the task thank you

Last edited: Jul 30, 2010
4. Jul 30, 2010

### bharata

would electrons be possibly composed of something?

5. Jul 31, 2010

### bharata

Hey, what is the use of leptonic numbers?

6. Aug 1, 2010

### eXorikos

In the Standard Model electrons are elementary particles. Beyond the SM there are theories that say leptons are composed of smaller particles (eg. leptoquarks). Although those are just theories and there is no experimental evidence. (as far as I know)

They came up as bookkeeping devices that say which reactions are allowed and which aren't. Only reactions that conserve electron, muon, tau number are allowed. Maybe in Quantum Field Theory they come out of the theory itself, I haven't had a QFT course yet.

7. Aug 19, 2010

### bharata

Hello again...I'm back! Now I got another amazing physics investigation :D
This assignment is due next week and it's about the Large Hadron Collider (LHC)
The task requires me to write the research of its development and application, purpose, use of fields in and the limitations of device. Including the relevant mathematical treatments of the information.