Particle Physics : Now and the Future

David MilsteadStockholms Universitet

The most important questions in modern physics

The most important experiment in modern physics

Physics as a career

Open questions for the curious physicist

What are the fundamental building blocksof matter and what are the forces whichact on them ?

Why do particles have masses ?

Why does nature seem to dislike anti-matter ?

What is dark matter and dark energy ?

Nature’s building blocks (so far)Nature’s building blocks (so far)

proton

W,Z,g, force

Standard Model of Particle Physics

Forces between particles

e- e-

e+e-

q q

Z

g

Looking for a single super force !

Electromagnetism

Weak

Strong

Gravity ?

-

Anti-matter is rare (<<1%). Why ?

How do particles get mass ?How do particles get mass ?

t

bc

s

ude

e

Massa

Peter Higgs theory explains why particles get mass.

To prove the theory we must find a new particle: Higgs boson

Energy in the Universe

Atoms

Dark matter 25% Dark energy

70%

We can’t understand 95% of the energyin the universe

Supersymmetry

A new family of particles

Predicted to appear at the LHCOne of them could be dark matter

Story so far

• Protons are made up of quarks. What are quarks made up of ?

• Are there more quarks ?• Can we find a single super force ?• We can’t understand 95% of the

universe’s energy – what is dark matter?

• Where did the anti-matter go ?

Go back to the start

First mammalsFirst DNA

Nu (15 billion years)Solar system

10-36 10-6 10-2

Matter-antimatter asymmetry

The electromagnetic weak forces separate, Higgs

Quarks become bound in protons

sekunder

Big bang

+ dark matter, dark energy.

microscope

AcceleratorNaked eye

binoculars

Telescope

Measuring large and small objects

Accelerators collide high energy particles to recreate the early universe and look inside a proton!

Collide a particle with a proton and study quarks

We can also produce newparticles via E=mc2 -Higgs, SUSY etc.....

The second most useful relation in physics

LHCLarge Hadron Collider collides protons with energy 7 TeVIt starts in 2007

Each proton beam has energy = aircraft carrier at 10 knots

LHC vs Stockholm’s underground

LHC Blue line

Length 27km 16 km

Depth 100m 20-30m

ATLAS experiment

Five levels high

7,000,000 kg 42m length 22m wide 22m high2,000 physicists 150 universities 34 countriesThe goal is to discover new particles!

How can we find the Higgs

boson/SUSY ?

We are developing the WWWs successor: the Grid

Concorde(15 Km)

Balloon(30 Km)

CD stack with1 year LHC data!(~ 20 Km)

Mt. Blanc(4.8 Km)

Search through 20,000,000 collisions for one Higgs boson or several SUSY particles

LHCs data corresponds to 14 million cds every year

We will need 100,000 computers to analyse the data

We start with this

And look for this signature in the mess

Finding the Higgs boson

• 800,000,000 proton-proton interactions per second

• ~100,000,000 channels

• 0.0002 Higgs per second

Nature’s mirror doesn’t work

Process B is a mirror image of process A. Process B uses the anti-particles of process A.

We can measure a difference between them.Could explain why the early universe lost its anti-matter!

Summary of the physics LHC is one of the world’s most ambitious

scientific projects

It will address many of the most important questions in modern physics

- What is mass ? - Matter anti-matter - Dark matter + much more.. Particle physics looks forward to a bright future

Research Physics as a career

• 3-4 years undergraduate (BSc/MSc) + 3-4 post-graduate (Ph.D.)

• 2:2 upwards required• Be prepared to travel• Be prepared for several short term post-

doctoral jobs• Can jump off at any point to a far more

lucrative career

The best and worst aspects of my job

Cutting edge physicsTravel, new languages and culturesFree to do what I find interestingNobody asks what I’m doing

Applying for new grants/fundingTravel – impossible to stay put for a monthNobody asks what I’m doing