"New" Particles

There are 12 fundamental particles in the 'Standard Model'

This section involves quite a lot of memory work. Particles can be classified into leptons and hadrons.

Heavy Hadrons & Little Leptons

A very good animated review of the fundamental particles

The hadrons are the particles that experience all four forces of Nature, and they can be subdivided into baryons and mesons.

The leptons are those particles that do not experience the strong force, and the four types of lepton are the electron, the positron, the neutrino and the anti-neutrino.

Hadrons are the more massive particles while Lepton are lighter, the names actually come from the Greek for Heavy and Light :)

Mass of particles comes from energy of the reactions – m =

The larger the energy the greater the variety of particles.

Problems with the standard model

middling Mesons, big Baryons

Where is the Higgs Boson?

It has been found on July 4, 2012.

It is an extremely short lived particle that was predicted in 1962,

Gravity is not part of the standard model, although it is the best known of all the fundamental forces.

The model also predicts the existence of a special particle called a Higgs Boson that gives other particles their mass. We haven't been able to find or infer the presence of the Higgs Boson to date.

in the standard model of particle physics, the existence of the Higgs boson explains how spontaneous breaking of electroweak symmetry takes place in nature.

There are so many particles, collectively they are called “particle zoo”.

They have lots of different names and it can be difficult to recall them all but take heart:

even the great Enrico Fermi once said to his student (and future Nobel Laureate) Leon Lederman,

"Young man, if I could remember the names of these particles,

I would have been a botanist!"


There are 6 leptons

indivisible point objects, not subject to strong force, e.g. electron, positron, taon, muon and neutrino.

me < mL < Mp

leptons do not feel strong force

Leptons have charges in units of 1 or 0.

What is a neutrino,

Neutrinos are fundemental particles (they are not made up of other particles) in the Lepton family

The were proposed by Wolfgang Pauli (in 1931) in order to conserve, Charge, momentum and 'spin' in beta decay Nuclear reactions.

In 1932 James Chadwick discovered the particle, he called it a neutron.

3 Flavours of Neutrino

electron Neutrino tau Neutrino muon Neutrino

good history here ....


Kamiokande and look for images



e.g. protons, neutrons, and heavier particles.

subject to all forces, feels strong force

made up of 3 Quarks

The proton is the lightest Baryon


examples the Pion Kaon K+

subject to all forces,

mass varies between mass of electron and mass of proton.

Made of a Quark & an Anti - Quark

The Quark and Anti quark are not the same variety / flavour


Hadrons consist of smaller particles called quarks.

There are six types of quark:

up, down, strange, charm, bottom and top.

Protons consist of two up quarks and one down quark,

while neutrons are composed of one up quark and two down quarks.

Mesons are made of a quark and an antiquark.

All particles of Nature have a corresponding antiparticle.

The conservation laws of physics that have been encountered in mechanics (mass, energy, momentum), electricity (charge) and nuclear energy (mass-energy), are also obeyed in particle interactions.

Quarks (and antiquarks) have electric charges in units of 1/3 or 2/3 's.

"We don't allow faster than light neutrinos in here" said the bartender.

A neutrino walks into a bar.

Large Hadron Collider

Appropriate calculations.

Pioneering work to investigate the structure of matter and origin of universe.

International collaboration, e.g. CERN.

The Maths of how these particles are mapped are in Feynmann diagrams

Am nearly sure this app was made by Irish students for the Leaving Cert

CERN scientists estimate that, if the Standard Model is correct, a single Higgs boson may be produced every few hours. At this rate, it may take about two to three years to collect enough data to discover the Higgs boson unambiguously. Similarly, it may take one year or more before sufficient results concerning supersymmetric particles have been gathered to draw meaningful conclusions.[3] On the other hand, some extensions of the Standard Model predict additional particles, such as the heavy W' and Z' gauge bosons, whose existence might already be probed after a few months of data collection.


Here’s one for all you armchair particle physicists. Find out all about the ATLAS detector, have a go at spotting the Higgs, and best of all, download particle collisions live from CERN. You can then explore particle tracks inside ATLAS in full 3D glory – even if (like us) you don’t really know what’s going on, you have to admit it looks pretty cool.

Available on Android. Free.

Beta - is when a neutron decays to a proton, an electron and antineutrino

Beta + is when a proton decays into a neutron, positron and neutrino