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76 Cards in this Set
- Front
- Back
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define anisotropic |
not going all same direction |
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define electron volt |
kinetic energy gained by one electron when it is accelerated by one volt |
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define cross section |
model of a nucleus as a completely absorbing cross section |
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equation for einsteins relation and the reletivistic relation |
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units of cross section |
barn = 10^-28 |
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equation for fermi's golden rule |
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Born approximations |
- assume single scattering -initial and final states are defined by plane waves -ignore recoil from nucleus |
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equation for scattering amplitude Mfi |
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special cases of form factor |
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definition of a boson |
-integar spin -can be created and destroyed -are own antiparticles -symmetric when particles are interchanged |
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definition of a fermion |
-half integar spin -include constituent particles of matter -produced as fermion antifermion pairs -antisymmetic when particles are interchanged |
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definition of a quark |
Baryon number of ±1/3 up and down |
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definition of a lepton |
lepton number conserved electrons and neutrinos generations: Le Lu Lt (increasing mass) |
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define quantum mechanical potential |
probability distribution |
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define quantum field theory |
interacts at very small distances |
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define virtual photon |
only exist with the freedom of the uncertainty principle and for a short period of time |
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two types of field |
fermion acts as a source and boson propagates both fermion and boson are sources |
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source, particle, spin, mass and strength of strong force |
colour gluon spin 1 mass 0 ~1 at large distances and <1 at small distances |
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source, particle, spin, mass and strength of EM force |
charge photons spin 1 mass 0 ~10^-2 |
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source, particle, spin, mass and strength of weak force |
leptons and quarks W±, Z spin 1 mass 80-90Gev/c^2 ~10^-15 @10^-15m ~10^-2 @10^-18 |
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source, particle, spin, mass and strength of gravity |
energy density graviton G spin 2 mass 0 ~10^-38 |
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equations for momentum q and resultant force |
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reletivistic relation to wave equation |
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equation for yukawa potential |
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matrix element Mfi |
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propagator term |
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define invariance principle |
reflects a basic symmetry and is always related to a Conservation law |
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generator of translations |
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invariance in Hamiltonian |
leads to conservation of momentum |
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CPT invariance |
weak interactions are invariant under CP all interactions are invariant under CPT |
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combining conservation laws |
continuous transformation = additive discrete transformation = multiplicative |
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Charge operator Q |
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Partity operator P |
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Charge conjunction C |
changes particles into antiparticles |
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time reversal T |
reverses time coordinate |
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number for cross section, alpha |
1/137 |
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magnetic moment in terms of atomic and QM |
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anomalous magnetic moment a |
in order of alpha 1/137 |
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High order process for altering magnetic moment |
- electron surrounded by cloud of virtual photons - charge carried by electron - mass and energy shared by electron and cloud of photons - value of e/m for bare electron increases so magnetic moment increases |
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properties that lead to postulation of weak force |
- low rates and long lifetimes - violation of conservation laws - frequent involvement of neutrinos |
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cross sections at low energy |
cross section proportional to G |
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define strong interaction |
binds constituents of nucleons and other hadrons |
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properties of strong interaction |
- only acts on quarks - strong - overcomes coulomb repulsion -binds qqq or qqbar |
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what happens if a quark is ejected |
- colour field builds up and creates a quark antiquark pair to reduce fieldn - new pair are attracted to original particle and produced colourless meson and baryon |
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what colour can a quark be |
Red, green or blue |
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equations for electric charge |
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properties of isospin |
- hypothetical space - charge can be due to change in isospin - wavefunction is always antisymmetic - conservation of strong interactions |
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isospin of pions |
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isospin of nucleons |
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isospin of quarks |
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overall wavefunction |
must be overally antisymmetic |
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define strangeness |
unusual stability for strongly interacting particles - strange particles can only decay by weak interactions |
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charm quark |
- charge 2/3 - partner to s quark |
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3rd pair of quarks |
top/truth bottom/beauty |
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generation of fermions |
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symmetry of pn and np |
no defined symmetry |
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combining two nucleons |
no colour and therefore spin and isospin need to be antisymmetic |
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combining quarks |
has colour so isospin x spin must be symmetric |
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weak isospin |
T, T3 doesn't conserve quark flavour |
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dc and sc |
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most likely decay chain |
t > b > c > s > u |
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strong and weak eigenstates of down and strange |
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mixing matrix of three generations |
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k0 reaction |
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k0 bar reaction |
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k1 and k2 |
distinguished by their weak decays |
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distinguishing between k0 and k0 bar |
weak interactions don't conserve strangeness but CP is conserved |
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strangeness regeneration |
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electron positron annihilation |
produces particle antiparticle pair that proceeds through a time like virtual photon |
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cross section for energies at 2x rest mass of quark |
cross section = z^2e^4 |
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ratio R |
must be over all colours and flavours |
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R at low energies |
2 |
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R at higher energies |
3 1/2 - 3 2/3 |
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inelastic scattering |
- evidence for point like particles |
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elastic scattering |
- if you take nucleons to be made of point like particles then q^2/2mv will be constant for elastic scattering however quarks are not at rest |
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k0 at low energies |
only get pure samples of k0, no k0 bar |
