Matter                                Antimatter

p+                                     ¯p- (anti-proton)

e-                                      e+ (positron)

n                                       ¯n (anti-neutron)

Placed metal bar in center of detection field.

Loses energy when hits bar, can see from where it came

Because the direction of the tracks..

must be positively charged= e+

From cosmic rays= emit high energy sttuff

Nature's accelerator

A theory by Pukawa predicted that what mediated strong interaction

mass?

particles called pions

approx. mass of electron

How was the muon discovered

What is it?

discovered in photographic emulsion that was exposed to cosmic rays.Did not interact with protons

The muon= secong gen particle that looked like a heavier electron

Strange particles

How were they identified?

mass?

make "v" like tracks

produced by a new particle= k particles

mass=1/2 of proton

Pauli invented what particle?

Why?

Problem with neutrino

Neutrino

to help with the problem of conserving E and P

Can't interact with EM, need new force

W particle

like pions and strong force

What is a baryon?

what are not?

Something that consists of 3 quarks

pi, muon, electron and k particles

the # of strange quarks

get more strangeness the more mass you have

Particle accelerators were invented to do what?

unit?

to control production of large #s of particles

to produce high-energy beams

Use E and B field combos to ramp up energy of particles.

Unit= elecron volt

Cyclotron

Cosmotron

LHC

in the 50's how did particles show up as in scatering data?

Why couldn't they see them?

Resonances (series of particles)

Particles decayed too fast~10^-23 sec

all types of quarks

charge and strangeness

                          q                      s

u=up               +2/3                   0

d=down           -1/3                    0

c-charm             +2/3                 

s=strange          -1/3                  -1

t-top                  +2/3

b-bottom             -1/3

How was the quark model proved

what did they find

used a linear accelerator

shot electron beam at liquid hydrogen

if proton was ball of energy-expect beam to go right through=not observed

OBSERVED= back scattering-happens if had quarks

constituents.

found: 3 quark constituents

proton=uud

All observable particles are either

baryons= 3 quark combo=q₁ q₂ q₃

eg. (p,n, sigma+)

or Mesons= quark–antiquark pairs₁ ¯q₂

eg. (k+, pi+)

November revolution. e- and e+ collider and SPEAR and exp. at AGS observed what?

What did this lead to?

new fairly stable particle

name= J/4

new meson w/charm quark

tau

leptons:         Q

tau neutrino= 0

tau          =   -1

bottom quark

Quark         Q

T-top        = +2/3

b-bottom  = -1/3

very large m_top=170 GEV

m_bottom =4.7 GEV

electromagnetic — photons

weak — w-,w+, z0

for strong interactions between quarks

used generalized photons (gluons)

3 types of elec charge for quarks

COLORS! red, gree, blue

8-diff colored gluons in this theory

rule regarding colors

all observable paarticles must be color neutral or white

white= 3 quarks or particle-anti particle combo

problem with color theory

what was invented to fix this

theory requires all matter problems to be massless (weak interaction theory)

Invented Higgs particle to fix this and generate mass.

At very high temps=higgs behaves as force mediator

at low energies, Higgs field freezes out=generates mass.

QED=electromagnetic — photons

?=Weak Force — w+,w-, z0

QCD=Strong force — gluons

Higgs — H

discrepancy btwn solar Ve production and the # of neutrinos observed from sun.

saw only 1/2 of predicted particles

reason: Neutrinos can cause oscillations=mass

a particular type of star that varied in brightness over time.

Period of oscillation realted to luminosity-standard candle

measure distance that the stat moves during the year

Variable star brightness: the shorter the period, the dimmer the star

the longer the period, the brighter the star.

How to measure distance to star

what did hubble realize

use star luminosity which is gained from stellar parallox

this allowed hubble to see that the cloud of gas he saw was 100 x further away than any star in our galaxy=universe is huge

To test motion of a star:

what did this show

Doppler effect, a star in motion and its light wavelength shift corresponds to color shift.

For star moving away, spectrum is red-shifted.

showed that galaxies are moving away from us

was developing general relativity, found equation had no time independent solutions. Always found either contration or expansion of space. Decided to include an extra term to get rid static solution.

w/out the constant he had redicted the expanding universe

71(km/s)/ mpc

mega=3 million light years

1 par sec=3.26 light years

sun and planets begin to form

when stars collapse, they create all the elements and as it explodes, elements shoot off and end in gases where gravity pulls dense objects togther

Timeline of early galaxy

8 bil

6 bil

1 bil

300,00

3 mins

10^-6sec

10^-12sec

8 bil yrs old=sun and planets begin to form

6 bil yrs old=milky way galaxy is in forming

1 bil yrs old = first stars are forming structure formation

300,000 yrs old= entire univ=one big molecule

-light did not propogate -as sson as light was emitted it was absorbed by another atom

at 3 mins old=entire univ was one giant nucleus

at 10^-6 sec= univ=one gigantic nucleon (quarks and gluons)

at 10^-12sec= Higgs particle melts-all particles are massless prior to 10^-12 sec.

get restoration of symmetry btwn EM and weak force

No idea-purely theoretical

possibly grand unification-symmetry would include strong force

need to include gravity in quantum way

light was able to freely travel through univ for 1st time

prior to 300,000=univ=one big molecule (plasma)

after=atoms form, more space, univ transperant to light

How was cosmic microwave background radiation discovered?

what is it?

used a radio antenna to look at sources in our galaxy

instrument was sensitive to low intensity radio and microwaves

heard random noise in the signal

thought it was pigions..but signal was still there

realized it was a real physical signal the CMBR

When an object radiates energy it does so across a variety of wavelengths

Nucleosynthesis- creation of new atomic particles from nucleoons (quarks and gluons)

which can be ued to measure the density of matter

at some point, a few billion yrs after star is formed, it burns up all the H fuel

gravity then takes over and it collapses the star material

then gets hotter and fusion begins again making heavier elements

then=BIG EXPLOSION-elements shoot off, emit light that can emit light brighter than the galaxy it is in.

- speeds of stars don't agree with calculations

pos. solutions.=

A.modify newtonian gravity-hard to do in a way that works with gen. relativity

B. Dark Matter-much more mass than is seen

-must not interact with photons or EM force

-neutrinos could work but are much too light

-motions of galaxies appear to be missing mass

Gravitational lensing=how mass cluster bend lights and affectd how we see stars-calculated mass is much larger than observed mass

Problems w/ Gravitational Lensing

indicates what?

frequently indentifies dark matter

more matter needed to bend the light to agree with calcs-90% is missing

don't know

but...doesn't interact with photon, if it did you would see it

3 catagories

1) Hot dark matter-ultra-relativistic speeds,close to c

2) warm darm matter: slower than hot but still relativistic

3) cold dark matter:slowly moving =, non-relativistic speeds.

1) MACHOS-Massive compact hale objects

-small invisible objects made of ordinary matter

2) WIMPS- weakly interacting massive particles

-postulate particles that interact only via weak interactions

idea: early univ-electrons and positrons and high energy collide to produce WIMPS

a. These events are very rare, 90% of matter should be happening more frequently

b. Nucleosynthesis-4% baryons

if this was right nucleosynthesis would be wrong (closer to one)

Bar vogenesis Theories

tries to explain what?

Process that violates Baryon # conservation, these occur in grand unified theories (GUTs)

why there is anti-matter and matter in the univ.

a. Age problem or flatness prob.

-ballance btwn matter and initial kenetic energy to get univ to live longer than 14 billion yrs

b. Smoothness prob.- CMBR is uniform across sky~same temp in regions that have never been thermal contact

c. Lumpiness prob. -universe is not a symmetrical ball of gas

Our universe is expanding at an exponential rate

fixes prob of flatness problem=curvature naturally flattens out-universe large automatically due to inflation

fixes prob of smoothness-small bit @same temp initially

fixes prob of lumpiness-might have small quantum fluctuations of "small bit"-tiny QF's can expand to structure of univ.

1)cyclic models for univ.-repeated expansion and contraction in cycle- univ. oscillates

-string theory

2) Cosmic strings-field at GUT scale can wrap up into sring like structures that extend across large portions of univ.-studies of CMBR don't match model

Supernovae-prob with hubble law

explanations?

supernovae too dim

1)dust--bt only happens at great distances

2) universe is accelerating expansion

-dark matter may be why gravity is isn't causing deceleration as it should

omega>1=energy density is large enough for recollapse

omega<1=not enough energy density for re collapse

omega=1=flat

1) luminous matter (baryons)

2) Dark matter?

3) Dark energy

1. initial guess-based on observations

2. compute consequences of guess

compare calculated consequences w/expts

4. if expts disagree with consequences, then theory is wrong

Quark model-

developed substructure of all mesons and baryons

generalized electromagnetic force-photon to incorporate weak force- z,w,w,gamma

needed to break smmetry using higgs to get theory to work.

a further generalization of symmetry used in electroweak (w/out the breaking higgs)

QCD-

1 photon—8 gluons

THere are no quantum versions of theory

and cannot test...

Kaluza-Klein theory

prob:

wrote down theory of gravity in 4 space dimensions in one time

not visually defined, but mathwise works fine

curled up extra demension into tiny circle that you cant see

prob:makes prediction that EM force is equal to the strength of gravity.

an attempt to undrstand meson dynamics

didn't work

came back as fndamental theory of nature

quarks, leptons, photons etc=variety of string occilations

included closed string--behaves like gravity-graviton

lowest string mode for closed string was tachyon (not graviton)

tachyon= particle that always is faster than c

but don't really exist

===UNSTABLE

prob 2: need to curl up extra demensions to get theory to work in 4d

String theory:

using supersymmetry

each observed particle must have a superpartner

photon — photino

electron — selectron