The Standard Model of Particle Physics Piet Mulders [email protected] mulders Studiedag Natuurkunde en Sterrenkunde.

The Standard Model of Particle Physics

Piet Mulders

[email protected]

http://www.nat.vu.nl/~mulders

http://www.wyp2005.nl

Studiedag Natuurkunde en SterrenkundeFeb. 10, 2005

The Standard Model of particle physics

• The particle content• Experiments; matter and antimatter• The fundamental forces• Force carriers• Central theme of Standard Model: symmetry• The history of the universe• Remaining questions in the standard model

• Mass and structure of space-time• The mass in the universe• Neutrinos

The particle content

http://www.nat.vu.nl/~mulders P.J. Mulders home

TheoryExperimentApplication

Materie

MATTER

A bit more or less Hydrogen in metals like Yttrium-Palladium (Griessen)

REFLECTING

TRANSPARENT

Materie

MATTER

ELECTRONATOM10-10 m

The periodic table

Materie

MATTER

ELECTRONATOM10-10 m

MATTER

ELECTRONATOM10-10 m

NUCLEUS10-14 m

NEUTRINO

ATOM10-10 m

ELECTRON

MATTER

NUCLEUS10-14 m

NEUTRINO

NUCLEONproton/neutron10-15 m

Atomic nuclei

Island of stability

Atomic nuclei

• Isotopes• Radioactivity

alphabeta gamma

after 15 min.

Neutrinos

more on neutrinos

Building blocks of the subatomic world

Materie

ELECTRON

MATTER

ATOM10-10 m

NUCLEUS10-14 m

NEUTRINO


ELECTRON

MATTER

ATOM10-10 m

NUCLEUS10-14 m

NEUTRINO


QUARKup/down

Basic building blocks of matter

home

How do we know this?


By using the largest microscopes on Earth

Antiparticles

Standard model content

• 3 particle families

The fundamental forces


Forces in daily life

Electromagnetism Gravity

• Two of four basic forces• Both based on fundamental principles

Standard model

• 3 particle families• 4 fundamental forces

• strong force quark nucleon atomic nucleus• electromagnetic force atom molecule complexity• weak force decay

• gravity

UNIFICATION

more on gravity

Standard model

• 3 particle families• 4 fundamental forces• Corresponding force particles

And a consistent theoretical framework: a renormalizable non-abelian gauge theory

Steven WeinbergSheldon GlashowAbdus Salam

Gerard ‘t HooftMartinus Veltman

How is the action of force particles


Force carriers of weak interactions

Force particles play a role in:

Interactions Pair creation Annihilation

Example: neutron decay

Neutron beta-decay

At the quark level

n p + e + e

d u + e + e

Three kinds of neutrinos!

Z0 decay into: quark pairs (except top quarks!) lepton pairs

ee, , neutrino pairs (‘invisible’)

lifetime is inverse of decay probability

i

colli

ssio

n p

robabili

ty

energy (GeV)

weak

electromagnetic

Strength of interactions

GF ~ /MW2

strong

How do quarks and gluons give the proton its properties?

A one-line theory: QCDMassless quarks

and gluons

Protons and neutrons:Basic constituents of atomic nuclei forming99.5 % of the visible mass in the universe

QED versus QCD

This implies a constant force T0 = 1 GeV/fm = 20 Ton

Permanent confinement of colored quarks

short distances

large distances

Frank WilczekDavid GrossDavid Politzer

Mass of nucleon

• Almost massless quarks: mu ~ 5 MeV and md ~ 10 MeV

• constant force T0 = 1 GeV/fm leads to confinement of color over distances of ~ 0.8 fmPressure in bubble: B ~ 100 MeV/fm3 EV = 4BR3/3 ~ 200 MeV

• Momentum p ~ 1/R ~ 250 MeV

• Energy per quark: EQ ~ 250 MeV

• Total energy: E ~ 940 MeV = mass of nucleon

d uu

u d d

proton

neutron

Phase diagram of QCD

quark-gluon plasma

hadrons

nuclear matter

T

ud

A model calculation

q (MeV)

T (MeV)

Harmen WarringaDaniël Boer

Central theme of standard

model:SYMMETRY


Mirror symmetry

• Mirror world?• Example: top• Mirror world exist• Conclusion: mirror symmetry is a

symmetry of our daily world

Broken mirror symmetry

• A pion decays into spinning particles

• For a neutrino only one spin direction exist!

• But how can we measure this?

• spin + charge magnet

• Only observed at N-pole of the magnet!

lefthanded

For neutrinos there exist L but not R

mirror imagesrighthanded

CP symmetry

• Mirror symmetry (P) is broken in the subatomic world• Particle-antiparticle symmetry (C) is also broken• But … the combination is indeed a symmetryalmost

__ _K0 = ds, K0 = sd have slightly different masses and decay in a different way

CPT symmetry

Time reversal

• CPT is (to our present knowledge!) indeed a good symmetry of the world

• CP is almost a good symmetry• Thus also time reversal is almost a good

symmetry, but not exact!• This symmetry breaking allows for the surplus of

matter over antimatter in the universe (even if this is only 1 : 109)Number of baryons 0,25 x 1079 (~ 0,25 per m3)But the number of photons and neutrinos 1088 (~ 400 per cm3)

more on mass in universe

CP-violation in standard model

CP-violation can be implemented in the standard model through complex phase(s) in CKM-matrix.This requires at least three families!

CabibboKobayashiMaskawa

The history of the universe


BIG BANG

13.7 billion years ago

inflation

and finally now….

Remaining questions in the standard model

• 3 particle families• 4 fundamental forces• corresponding force particles• Glimp of the ‘Higgs particle(s)’?

… and very many questions remaining!

(Anti)matter in universe ??Black holes ?

Space and time ?Points ?Strings ?

Chaos ?

Phase tr

ansitions ?

Complexity

Hadrons Why 3 families ??

Neutrinos ?

Their masses ?


Where to find the answers?


In accelerators ?

• Collissions in the Large Hadron Collider at CERN– New particles

(Higgs, …)– New symmetries

(Fermion-Boson symmetry)

– Origin of mass – Origin of symmetry

breaking (e.g. CP-violation)

ATLAS

CMS

LHCb

(future) detectors at CERN

Super KamiokandeUnderground ?

Underground ?

• Atmospheric neutrinos oscillate over thousands of kilometers

• Solar neutrinos change flavor in the Sun

• Masses m ~ 0.01 eV

(that is extremely small, but compare k ~ 104 eV/K) Sudbury Neutrino Observatory (SNO)

In the mediterranean?or the ice?

• Looking for high energy cosmic neutrinos– Supernovae– Neutron stars– Black holes ANTARES

AMANDA

Answers in the sky?

Cold Dark Matter

Dark baryonicmatter (3.5%)

Normal matter: stars (0.4%)

Dark Energy

CosmicAccelaration

73%

23%

, ,lm lmaT Y

WMAP satellite

,T 2.7248K 2.7252KAngular Power Spectrum

l

0.4 100.3(6.5 ) 10baryons

photons

N

N

Cosmic microwave background

EINDE

home

Mass and the structure of space-

time


Mass: energy and momentum

Velocity of light: c = 3 x 108 m/s = 300 000 km/s

2

2

2

1 vc

mcE

2

21 vc

mvp

2 212E mc mv

p mv

If v much smaller than c

Mass: gravity

( )( )

GM Rv R

R

rotatiesnelheden in galaxies

2 2

3

4T

R GM

omloopstijden en afstanden(planeten, dubbelsterren)

2

2

Mm vG mR R

zwaartekrachtversnelling ac

bij cirkelbeweging

zwaremassa

tragemassa=

Mass: curvature of space-time

• Zonder kracht: rechtlijnige beweging

• Zwaartekracht wordt veroorzaakt door massa

• Massa bepaalt ook mate van respons (equivalentieprincipe)

Algemene relativiteitstheorie:Beweging in zwaartekrachtveld is rechtlijnige beweging in een t.g.v massa gekromde ruimte

GEEN KROMMING POSITIEVE KROMMING NEGATIEVE KROMMING

curvature

• Kromming van een bol: k = 1/R2

• Bijv voor voetbal: k = 50 /m2

• Bijv voor aarde: k = 2.8 x 10-14 /m2

• Andere methode gaat via hoeken k = /S()

The boomerang experiment

• 2 terra-cruisers• back and forth!

R = 42 min = 7.5 x 1011 mof = 20 m/s = 0.67 x 10-7

R = (16 km)/ = 2.4 x 1011 m k = 1/R2 = 1.6 x 10-23/m2 !!!

Vergelijk met ‘bol’:

space-time curvature

home

1 s = 3 x 108 m


The matter in the universe

Matter in the universe

Cold Dark Matter

Dark baryonicmatter (3.5%)

Normal matter: stars (0.4%)

Dark Energy

CosmicAccelaration

73%

23%

Evidence for Dark Matter

Rotation of galaxies Gravitational lenses Microwave background

Ultra High Energy Cosmic Rays

0,1

1

10

18 18,5 19 19,5 20 20,5

uniform distribution,

AGASA data (E 20%)

HiRes 1 Monocular

(E

)

E3 (

10

24 e

V2m

-2s-1

sr-1

)

log10

E (eV)

protons onlyData beyondthe GZK limit:new physics?

CMB

pionE

E’

Neutrinos


Origin of neutrinos

• Weak decay of atomic nuclei (Sun/reactors): …n… …p… + e + e (righthanded antineutrino)

…p… …n… + e+ + e (lefthanded neutrino)• Cosmic rays (decay of the pion)

+ (righthanded antineutrino)

+ + + (lefthanded neutrino)• Remnants of the big bang

just as photons (T = 2.7 K background) for all three kinds of neutrinos (e, en ) about 400 per cm3

Questions around neutrinos

• What are the masses of neutrinos

• Where are the neutrinos from the Sun?Half of them is missing!

How to detect neutrinos?

Neutrino detectors

Sudbury Neutrino Observatory(SNO)

Detection via cherenkov light emitted by particles moving “faster” than light

(from antares experiment)

Neutrino detection techniques

Neutrino detectors

Super Kamiokande

Neutrino oscillations in the atmosphere

• Neutrinos in the atmosphere are created in the decay of pions. These are mainly neutrinos

• If the neutrino is a quantummechanical superposition of two neutrinos 1 en 2 it gives rise to oscillations

Place and timeof measurement

Place and timeof production

Neutrino oscillaties in atmosfeer

• Superkamiokande showed oscillations depending on the distance L to the detector

• Oscillation-wavelength is thousands of kilometers mass smaller than 0.000 001 of that of the electron

• Nature of oscillations is

Consequences of mass

• Particles with mass must come as righthanded and lefthanded!

• This is only possible if the neutrino is its own anti-particle (as the photon, but unlike the electron)

Dirac and Majorana neutrinos

Fermion(general)

P = spiegelenC = deeltje-antideeltjeT = tijdomkeer


Diracneutrino


Majorananeutrino

Neutrino oscillations in the Sun

• Oscillations arise because the interaction of e with matter differs from the interaction of

(e ‘feels’ electrons, doesn’t!)

• SNO showed that what is missing on e appears as a different kind of neutrino

• Most probably these are oscillations of the type e

Neutrino mixing

Mixing pattern of neutrinos as for quarks with possibly also complex phases and CP violation

The Standard Model of Particle Physics Piet Mulders [email protected] mulders Studiedag Natuurkunde en Sterrenkunde.

Documents

gravity slide

universe slide

strong slide

transparent slide

earth slide

mulders home slide

quark updown slide

subatomic world slide