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Flashcards

NPP

Luisina Canto NPP Highers English 88 cards

NPP

Cards in this deck (88)

  1. 1Quarks ForcesEM, Strong, Weak
  2. 2Leptons ForcesEM, Weak
  3. 3Neutrinos ForcesWeak
  4. 4Gluon ForcesStrong Force
  5. 5Fundemental Force order (strongest to weak)Strong Nuclear, EM, Weak, Gravitaional
  6. 6Feymann Diagram purposegraphical way to describe particle interaction
  7. 7Feynman Diagram: Coupling strength QED Vertexamplitude prop e^n
    Prob prop e^2n
    Prob prop fine structure constant ^n
    n- number of verticies
  8. 8Basic relativistic variablesBasic relativistic variables
  9. 9Relativistic Kinematics Lorentz invariant equation of EMassless particles becomes E=|p|cRelativistic Kinematics Lorentz invariant equation of E
  10. 10Multiparticle system, total mass (relativistic)P_T= sum(P)
    E_T=sum(E)    Multiparticle system, total mass (relativistic)
  11. 11Total mass / Center of mass energy (invariance)Total mass / Center of mass energy (invariance)
  12. 12Is 4-Vector a lorentz invarient object?NO, but the length of a 4-vector is
    |P|^2= m^2c^2
  13. 13Four Vector exampledecay X->c+d (X rest frame)Four Vector example
  14. 14Conserved quantities in standard modelEnergy, momentum, Angular momentum, Charge
  15. 15Spin angular momentumSpin angular momentum
  16. 16Number of values spin in z direction has Sz2s+1
  17. 17Helicityprojection of spin along the particles momentum vector. EG h=+1/2 (when spin and momentum align) OR =1/2( when anti-aligned)Helicity
  18. 18Parity congugationreflects position vector of each particle through the origin.
    P=+/- 1    Parity congugation
  19. 19Charge conjugationflips all internal charges (particle -> antiparticle)Charge conjugation
  20. 20Conservation of charge and parity conjugation- EM and strong forces conserve C and P
    - Weak forces do NOT
  21. 21Decay- probability of survival until time t (S)λ - decay rate
    τ- lifetime    Decay- probability of survival until time t (S)
  22. 22collision of e + p -->Z, with mass_Z=91GeV/c^2Need COM Energy=sqrt(s) = 91GeV
  23. 23Number of particles after time t (decay)Number of particles after time t (decay)
  24. 24Half timeTime taken for 1/2 of the initial samples to decayHalf time
  25. 25Decay widthunstable state doesn't have an exact energy. . has energy units. width quantises the uncertainty of mass for particle with finite lifetimeDecay width
  26. 26Decay width vs lifetimeLarge lifetime = Low width
    Small lifetime = Large width
    Stable particles have 0 width
  27. 27Total decay ratesum of separate rates
  28. 28Total widthactual physical uncertainty of massTotal width
  29. 29Branching ratioProportion of decay to a particular modeBranching ratio
  30. 30Quarksu,d,c,s,t,b
  31. 31Leptonse,v_2,miu,v_miu,tau,v_tauc
  32. 32Cross section of reactiontotal target area = Adno
    effective target area presented to the incoming particle to cause a reaction    Cross section of reaction
  33. 33Reaction rate per unit area of targetφ= particle flux (particles/area/time)
    n= atom density= atom (quantity of atoms in molecule) density*Navogrado/Atomic mass    Reaction rate per unit area of target
  34. 34Mean free path lparticles will more this distance before interactingMean free path l
  35. 35Differential cross section - isotropic scattering caseprobability of scattering at a particular energy or angle...Differential cross section - isotropic scattering case
  36. 36Reaction Thresholdminimum (kinetic) energy of the incident particle for
    the reaction to occur; assume head-on collision, products stick together
    (i.e. the most favourable conditions lead to the threshold condition)
  37. 37RealtivityRealtivity
  38. 38UNITS1 fm = 10−15 m
    1 barn = 10−28 m2 = 10−24 cm2 = 100 fm2
    proton, neutron and amu masses are all around 1 GeV/c2
  39. 39UNITSm_proton*c^2~ 1GeV
    mass=GeV/c^2
    Momentum= GeV/c
    Energy=GeV
    r_proton ~ 1fm
  40. 40Calculating nn= atom density= atom (quantity of atoms in molecule) density*Navogrado/Atomic massCalculating n
  41. 41Feyman diagram propertiesIngoing lines: particles with well defines energy and momentum
    Verticies: place where actual interaction take place, each has a factor of the relevant charge associated with it (e when EM force). Number of verticies depends on forces.
    Between Varticies: mediator/force carrier and is virtual
  42. 42Reduced massReduced mass
  43. 43TISE using Coloumb potentialTISE using Coloumb potential
  44. 44Energy Eigenstate TISE using coloumb potentialEnergy Eigenstate TISE using coloumb potential
  45. 45Energy Eigenstates TISE using SHM potential mω^2r^2/2Energy Eigenstates TISE using SHM potential mω^2r^2/2
  46. 46EM Decay + Feynman Diagramat vertex:
    - Charged fermion (anti-fermion) radiates or absorbs a photon
    -
  47. 47Type of decay- excited state to a ground state of a composite particle
    -electron positron annihilation possible through reversal of one fermion line at the vertex
  48. 48Positronium decay- ground state decay to only even number of photons
    -higher state decay to only odd number
    - Dance between e and e+ before they anihilate
    - Energy levels: miu=me/2
    En=-6.8/n^2 eV
  49. 49Range of weak force¯h/mc
  50. 50Charge conjugationTakesevery particle and replaces it with its antiparticle
  51. 51Rutherford scattering- evidence of compact nuclei at core of atomsdistribution of scattering- theta, differential cross section.
    Result is not isotropic, falls rapidly with increase angle (due to small force at large angle)    Rutherford scattering- evidence of compact nuclei at core of atoms
  52. 52Rutherford scattering, with spinRutherford scattering, with spin
  53. 53Electron positon annihilation into muons (Feynman diagram)Electron positon annihilation into muons (Feynman diagram)
  54. 54Strong Force-Affects quarks and gluons
    -short range
    -Mediator: Gluons
  55. 55Quarks-6 quark: u,d,c,s,t,b
    Baryon number = +1/3
    - 6 anti-quark: u^-,...
    Baryon number= -1/3
  56. 56Gluons- only interact with quarks
    -massless
    -colouredL each has 1gs of colour and 1gs of anticolour
  57. 57Quark-gluon vertexQuark-gluon vertex
  58. 58gluon fine structure constantgluon fine structure constant
  59. 59Gluon self interaction- each gluon carries colour and anticolour
    1) Confinement
    2)Asymptotic Freedom
  60. 60Confinement- We never see single quarks of gluons but only hadrons.
    - never have a state with a non-zero strong charge on it
    -Gluons radiate more gluons so field lines increase while density stays constant, which means total energy becomes infinate which is impossible leading to confinement of gluons.
  61. 61Asymptotic Freedom- at short distance, force goes to 0
    -balloon modell
    -if quark hit (by photon), for a short time (doesnt go very far), it acts as if it is not a bound state at all
    - Force between 2 quarks at a distance - 14tonnes
  62. 62Hadrons- bound states of quarks
    -mesons q, baryons qqq
    - Must be colour singlet C=0 (COLOURLESS)
    -
  63. 63Colour singletsCan achieve C=0 in 2ways:
    1)symmetric sum over all colourless pairs
    2) antisymmetric sum over colourless triplet of each colour    Colour singlets
  64. 64BARYON chartBARYON chart
  65. 65Baryon wavefunctionTotal wavefunction must be ANTISYMMETRICBaryon wavefunction
  66. 66Meson- ground state J=0
    - Excited states J=1
  67. 67For baryon bound state massEb=binding energy >0For baryon bound state mass
  68. 68Magnetic dipole relationfundemental dirac eqMagnetic dipole relation
  69. 69Energy splitting due to mag dip momergy level splitting arises due to mag dip mom of circulating electron colupling to nuclear mad dip mom.Energy splitting due to mag dip mom
  70. 70Binding energy relation to spinK= constant of proportionalityBinding energy relation to spin
  71. 71Working to find mass. Ground state J=0, Excited J=1L=0 so J=sq+sq^-
    - use J^2 to find dot product to sub into binding energy    Working to find mass. Ground state J=0, Excited J=1
  72. 72Decay of baryon excited state- Decay to ground state through photon emission
    - RARE: EM force decay, so strong force decay would be preffered
  73. 73p+ meson decay-mostly decays into pion ρ+ → π+π
    -very fast decay: strong force with only 2 verticies    p+ meson decay
  74. 74Strong force decays-Very fast
    - order 10^-23 seconds
    - eg:
    K∗+ → K0π+
  75. 75Charge conjugation calcCharge conjugation calc
  76. 76Gluon addition- Gluon carries colour change
    -will produce a jet of hadrons
    - contribute additional term to cross section for hadron
  77. 77Angular information contribution-tell us about the spin of the particle
  78. 78Why is proton stable and neutron is not?SM -> Baryon number must be conserved
    - Neutron can decay to a proton (mp
  79. 79Neutron decayn → p + e− + ̄νe + νμ
    Conserve momentum by recoiling both neutrino and antineutrino
    against the electron.
  80. 80SEMF*Insert pic*
  81. 81Volume TermThe nuclear force is short range so the
    most important contributions come from the neighbouring nucleons. The principal contribution to the binding energy therefore scales with A.
  82. 82Surface TermCorrection to reduce the binding energy to take into account the fact that the nucleons on the surface have fewer nearest neighbours than those in the centre.
    Nuclear radius scales with A, so, term is proportional to A^2/3
  83. 83Coulomb termElectrostatic repulsion between protons
    produces a potential that reduces the binding energy.
    The A contribution scales with the number of proton-proton pairs, i.e. Z(Z − 1).
  84. 84Asymmetry TermNuclei with the same number of protons and neutrons are observed to be more stable, i.e. the binding energy is larger.
    This is a “penalty term” proportional to. the asymmetry in the numbers of protons and neutrons.
  85. 85PairingPauli exclusion principle implies that nucleons must be added to the next energy level up if two protons or two neutrons occupy the same energy level
    with opposite spins. So, if the nucleus contains an even number of protons and an even number of neutrons δ > 0 and the binding energy is increased.
    Conversely, if Z and N are odd, then δ < 0 and the binding energy is reduced.
    For even/odd or odd/even nuclei δ = 0.
  86. 86Electron- positron annihilation into quarksElectron- positron annihilation into quarks
  87. 87Quark electric chargee_q instead of e
    Amplitude(qq) ∝ eeq ,
    Cross section: σqq ∝ e^2eq^2
    = e^4(eq/e)^2 ∝ α^2(eq/e)^2 .
  88. 88Cross section for hadron productionCross section for hadron production

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Highers NPP Flashcards on NPP, created by Luisina Canto on 09/03/2022.
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Luisina Canto
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