Phy489 Lecture 3
1
So far
Fundamental interactions in the Standard Model (SM)
Mediated by particle exchange
Three fundamental forces
have different effective strengths
act over different timescal
PHY489/1489 (2013) Assignment #1 Solutions (Oct. 15, 2013)
I have some comments on the answers to the first problem on the assignment.
1) The problem stated that you had to
Physics 489 (Fall 2013) Assignment #2
Due Wednesday Oct. 23, 2013
Do all problems. They are of equal value. As usual the policy on late assignments (and
other assignment related issues) can be found o
Phy489 Lecture 2
Standard Model Particle Masses
0.511 MeV/c2
Fermions
( spin )
Matter particles
106 MeV/c2
e
e
e L
ue L
~150 MeV/c
u L
d
d L
~150 MeV/c
, Z 0
W
0
W gZ
,
2
2
Bosons
( spin 1 )
Fo
Phy489 Lecture 2122
0
Chiral Fermion States & Electroweak UnicaBon
QuesBon: how can we contemplate unifying two forces that appear to have couplings
that are very dierent
Phy489 Lecture 20
Neutral Weak Interactions
Unification of the electromagnetic and weak interactions (Glashow, Weinberg, Salam) is
discussed in 9.7. We will cover some of this, but only briefly
Discus
Phy489 Lecture 4
1
Special Relativity: Lorentz Transformations
not accelerating
y
S
y'
S'
v
x
Consider two inertial reference frames S
and S' having a relative velocity v (which
we will align along th
PHY489 Lecture 18
Electrodynamics of Quarks and Hadrons
Here we wont discuss contribution from the weak interaction (yet). Note that QED
describes the interaction of the photon with charged spin-1/2 f
Phy489 Lecture 19
Charged Weak Interactions
Fundamental charged weak interaction leptonic vertex:
Here, a lepton emits (absorbs) a W- (W+) and transforms into neutrino
of the same lepton species.
W
He
Phy489 Lecture 9
Discussion is of baryon wavefunctions because baryons are
made up of three quarks (which are treated here as identical)
while mesons consist of distinguishable particles since they ar
Phy489 Lecture 6
Reminder about invariant mass:
2
A system of n particles has a mass defined by M INV c 2 = PTOT PTOT where PTOT
is the total four momentum of the system PTOT = p1 + p2 + p3 + . + pn
2
Phy489 Lecture 7
0
Clebsch-Gordan Coefficients
| j1m1 > | j2 m2 > =
j1 + j2
j =| j1 j2 |
C
j j1 j2
m m1 m 2
| jm > m = m1 + m2
Two systems with spin j1 and j2 and z components m1 and m2 can combine to
PHY489 Lecture 13
Feynman Rules for Fundamental Processes
So far we have learned about:
particle content
interactions (allowed vertices)
conservation laws
relativistic kinematics
Fermis golden ru
Phy489 Lecture 11
Question
Why are
(
K *0 K *0 oscillations not observed experimentally ?
K *0 is the same as K 0 but with spin-1 instead of spin-0. )
K0
sd
spin 0 M (K 0 ) 498 MeV / c 2
K *0
sd
spin
PHY489 Lecture 14
The Dirac Equation
First a reminder (hopefully) from non-relativistic quantum mechanics:
E=
2
p
2m
+V
To express this in the form of a wave equation we make the operator
substitution
PHY489 Lecture 12
Fermis Golden Rule for Transitions
transition probability
W=
Mif
matrix element
2
2
2
Mif f E
()
= f Vif i
2
Density of final states
available for energy E.
Matrix element contains t
PHY489 Lecture 15
Solutions to the Dirac Equation
(
)
=
here the matrices are 4x4 and is a 4-component Dirac spinor
Still need to discuss the form of the spinor :
We had i mc = 0 :
1
2
3
4
Consid
Phy489 Lecture 9
1
CP Violation
Standard Model contains only left-handed neutrinos and right-handed anti-neutrinos
C L = L
charge conjugation not a symmetry of the weak interaction
P L = R
parity also
PHY489 Lecture 16
0
Quantum Electrodynamics
Follow Griffiths sections 7.5-7.7 + example 7.7 from section 7.8, using
the e- e- scattering as an example.
Feynman rules for Quantum Electrodynamics
e- e-
PHY489/1489 (Fall 2013) Assignment 1
Due Wednesday Oct. 2, 2013
There are 7 problems on the following two pages. Do all of them. Total points = 60.
Please take note of the following:
When comparing to