Standard Model Subatomic World Protons neutrons and electrons

Standard Model

Subatomic World ] Protons, neutrons, and electrons make up atoms. ] Photons are particles that convey electromagnetic energy. • Force carrier ] These make up most of the material universe.

Artificial Particles ] Unstable particles can be produced. • Unique mass energy • Characteristic lifetime ] The lifetime t is related to the probability that a particle will survive a given period of time. ] The survival time is affected by relativity.

Leptons ] Leptons are fundamental ] Charged leptons: particles. • Interact weakly – no nuclear interaction • Able to exist in isolation ] Electrons are stable. • Muons and taus are unstable. ] Neutrinos are stable and very low mass. • Partner with charged leptons • electron, e-: 0. 511 Me. V/c 2 = 1/1836 mp • muon, m-: 0. 1057 Ge. V/c 2 = 1/9 mp • tau, t- : 1. 776 Ge. V/c 2 = 1. 9 mp

Baryons ] Baryons have atomic mass comparable to protons and neutrons. n • Conserved quantity p ] First artificial ones were given S- S 0 L S+ a property of strangeness. • Quantum number ] Later ones were given new X- X 0 properties. • Charm, beauty, truth

Mesons ] Some artificial particles were lower mass than baryons. • No atomic mass conservation ] Mesons are also had same quantum properties as baryons. • Strangeness conserved

Quarks ] Quarks are fundamental building blocks, but are not detected directly. • Binding force too great • Stable quarks bind to others ] Quarks exist in hadrons. • Baryons are three quarks • Mesons are a quark-anti quark pair. ] Some baryons • proton, p: uud • neutron, n: udd • lambda, L 0: uds • lambda-b, Lb 0 : udb ] Some mesons • pi-minus, p-: ud • k-plus, K+: us • J/psi, Y: cc

Standard Model ] The fundamental particles can be placed into a compact table. • Standard Model • Separate matter from force carriers ] The leptons and quarks fall into three related generations. • Normal mater in first generation next