The Higgs Boson

Valerie Rapson Astrophysical Sciences and Technology

Graduate Student

Rochester Institute of Technology

Outline What is the Higgs boson?

Standard Model of particle physics

Higgs field and the mass of objects

Discovering the Higgs boson

The Higgs and Dark matter and energy

What is the Higgs Boson A super tiny (sub-atomic) particle which allows objects

to have mass.

Mass vs. Weight Mass is how much space we take up (doesn’t change)

Weight is how hard gravity pulls on us (changes)

Weight

Mass always = 12 pounds

What are we made of? Humans are made of cells which are made of atoms

Atoms contain protons, neutrons and electrons

Electrons (-)

Protons (+)

neutrons

What are we made of? Protons and neutrons are made of quarks

Up Quark

Down Quark

What holds it all together? If opposite forces attract, and like forces repel, why

doesn’t the nucleus fall apart?

The strong force!

Four Forces of Nature

Standard Model The standard model of particle physics describes the

particles that exist, and how they make up matter

Building blocks

of particles

Some basic

particles

“glue” that binds

things together +

-

-

Bosons and Fermions We can group these particles into categories called

bosons and fermions

Fermions make up all matter

Fermions Bosons

+ Higgs and Graviton

Mass of Particles The ultimate question is why? Why do some particles

have more mass than others, and why do some have no

mass at all?

Higgs Field The Higgs field is an “invisible” field made of Higgs

bosons

Empty space is filled with the Higgs field

Higgs Bosons and Mass The Higgs bosons that make up the Higgs field give

objects mass

Imagine you are at a party….

Higgs bosons

Higgs field

Higgs Bosons and Mass …And a famous scientist walks through the door…

Higgs Bosons and Mass …the partygoers will crowd around the scientist, making it

harder for him to move through the room. He feels more

massive…

Higgs Bosons and Mass …a less famous scientist enters, and a few partygoers go

talk to him. It’s easier for the second scientist to travel

through the room and thus he is less massive.

An Alternate Explanation…

"If the constituent parts of matter were sticky-faced toddlers, then the

Higgs field would be like one of those ball pits they have in the

children's play area at IKEA. Each colored plastic ball represents a

Higgs boson: collectively they provide the essential drag that stops

your toddler from falling to the bottom of the universe, where all the

snakes and hypodermic needles are.”

-The Guardian

History of the Higgs Pre-1960’s, the Standard Model said electrons and

quarks should have no mass

Experiments say they do!

4*10-27 lbs 2*10-30 lbs

0.000000000000000000000000004 pounds!

History of the Higgs In 1964, 3 groups came up with a theory that slightly

tweaked the Standard Model and gave those particles

mass

Called this entity the Higgs field after Peter Higgs

Peter Higgs

U. Edinburgh

Carl Hagan

U. Rochester!

History of the Higgs Mass is acquired via spontaneous symmetry breaking

Oxygen molecule

O

O

High temperature Low temperature

History of the Higgs Higgs bosons break symmetry of the field when they

crowd around particles

Searching for the Higgs Scientists began using particle accelerators in the 1980’s

to search for the Higgs boson

Goal: smash two particles together with enough force to

create the highly energetic particle called the Higgs

boson

Fermilab Batavia,

IL

Properties of the Higgs Higgs boson has energy between 115 and 180 GeV

E=mc2 4.2 * 10-25 pounds

125x proton!

Spin=0 (symmetric)

Charge=0 (neutral)

Life: 10-23 seconds!

Large Hadron Collider at

CERN World’s largest and most powerful particle accelerator

Located near Geneva, Switzerland

LHC at CERN Look for elementary particles either by creating them or

breaking particles apart

P+ P+

?? ??

??

LHC at CERN Often don’t see the particles directly, only detect the

patterns left behind by their decay products

Recipe for a Higgs The LHC has enough power to crash two protons

together to search for a Higgs boson

2 protons 2 gluons virtual top and bottom quark

Higgs boson 4 muons

Simulated

Elusive Higgs The Higgs boson is hard to find!

1. Takes a ton of power to make one

2. Survives for such a short time

3. The same decay products are made by colliding many

other particles

Discovery Discovery of a particle with properties similar to that of

the Higgs boson were announced July 4th, 2012

4 * 10-25 pounds

Seen multiple times in 300 trillion collisions

2 independent groups confirm

Decay pattern similar to what

was predicted

More follow up needed

More than one Higgs? Supersymmetry is the idea that the universe, on the most

basic scale, is very simple and symmetric

Suggests that many different types of Higgs bosons can

exist

Which one did we find? Does it fit the standard model?

Dark Matter and Dark Energy

Composition of the Universe

The Existence of Dark Matter Imagine rolling a coin down a gravity well, or rolling a

marble around inside of a funnel

As the object gets closer

to the center, it orbits the

center faster

This is what we expect for

stars orbiting in a galaxy

The Existence of Dark Matter That is not what we observe!!

Must be some hidden

energy causing stars to

speed up!

The Existence of Dark Matter The universe is expanding at an accelerating rate!

Is dark energy speeding it up?

Higgs and Dark Energy The Higgs boson and dark matter are not the same

It’s existence may help explain what dark energy and dark

matter is, and how it works

Conclusions We await further confirmation that scientists have

discovered the Higgs boson particle

If so, it explains why objects have mass and confirms the

Standard Model of particle physics

The Higgs field will hopefully shed some light (pun

intended) on dark matter and dark energy

Supersymmetry????