Professor Steve F King presented his 'The Standard Models In Particle Physics' talk to Cafe Scientifique, Isle of Wight on 13 April 2015.

1. 1
A Tale of Two
Standard Models
Steve King, Shanklin, Isle of Wight, 13th April, 2015

2. 2
This is a tale of two Standard Models
• The Standard Model
of Particle Physics
• The Standard Model
of Cosmology
• And the connection between at the Large
Hadron Collider. . .

3. 3
Angels and Demons

4. 4
We are all familiar with antimatter… yet…
…it is a mystery why the Universe contains any matter at all

5. WQuestions about the Universe
The origin of matter – why was there a tiny excess of matter over
antimatter in the Universe, at a level of one part in a billion?
The origin and fate of the Universe – and why is it so big and flat?
The dark side of the Universe – why is 95% of mass-energy in a
form that is presently unknown, including 27% dark matter and
68% dark energy?
Sound of the
Big Bang
5
The Standard Model of Cosmology

6. 6
Dark matter is observed in the
collisions of galaxy clusters

7. 7
Dark matter is observed in the
collisions of galaxy clusters
Atoms (red gas)
Dark matter particles
(blue gas)
Dark matter particles
(blue gas)
What are the dark particles?

8. To answer such questions we need to
look back in time to the Early Universe
Hubble Space Telescope
8

9. 9
WMAP movie

10. If we want to
understand the
dark matter
particles in the
Universe we
must recreate
the high
energies of
the Big Bang
10

11. To do this we need a high energy
particle accelerator
11

12. 12
1. The resolving power of a microscope is
limited by the wavelength of the light.L
Why “High Energy”?
Actually there are three reasons:
e.g. bats use high frequency
sonar with wavelength less
than or about same the size
of an insect.
L
L
So, like bats, to see small things we need light with small wavelength
and high frequency – hence high energy photons since E hf=

13. 13
2
E mc=
2. Einstein taught us that
So high energy is
equivalent to large mass.
With high energies we
are able to produce very
heavy particles.
The basic unit of energy is the
“electron Volt” which is the energy that
a single electron receives when it passes
from the negative terminal to the
positive terminal of a 1 Volt battery.

14. 14
3. Boltzmann taught us that E=kT so high energy
means high temperature where is Boltzmann’s
constant. In the early Universe, just after the big bang, the
universe was very small and very hot.
So high energy physics teaches us about the early Universe.
kT
E

15. 15
What have we learned from High Energy Physics?
- Matter is made of particles (“particle physics”)
Answer: only 84 times! A single atom
nanometre
A nucleus
with orbiting
electrons
To understand this, take an apple and a knife, and cut the apple in
half once. Then cut one half in half again. Then continue the process.
After some number of cuts you will arrive at a single atom.
Question: how many cuts are required?

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−
−−
−
−
−−
−
-
+
+
+
+
−
−−
−
The electrical
attraction is
caused by
photon
exchange

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It is made of protons (p) and neutrons (n)
The nucleus of the atom is positively charged
The protons and neutrons are made of charged quarks
The quarks also carry a new “colour charge”
The quarks
are stuck
together by
gluons

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This decay process is very weak (15 minutes is an eternity!)
Without such weak interactions the Sun would shut down!
The (free) neutron is radioactive and beta decays after 15 minutes
into proton, electron and “neutrino” (electron-like neutral particle)
Nothing lasts for ever

19. 19
The Four Forces of Nature

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The Standard Model

21. The quest for unification – can the three known forces of the
standard model (and gravity) be unified?
The problem of flavour – why are there three generations of
quarks and leptons?
The origin of mass – what is the origin of all the particle masses?
Unanswered questions
21

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The Higgs Field is
the giver of mass

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The Higgs Boson
In the “Standard Model” the origin of mass is
addressed using a mechanism named after the
British physicist Peter Higgs.
This predicted a spinless particle: Higgs boson
According to
Higgs, space is
filled with a new
type of field
analagous to
magnetic or
electric fields…

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Higgs only introduced the boson after
his paper was rejected for not having
any predictions

25. 25
Particle Fever movie

26. 26
The CERN Large Hadron Collider (LHC)
Atlas

27. 27
LHC movie

28. 28
Brief History of the LHC
10th September 2008 - LHC switched on
– BBC devote a whole day of coverage to “Big Bang day”
-Soothsayers predict the end of the World
- Scientists at CERN celebrate

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Brief History of the LHC
19th September 2008 – LHC explosion due
to bad soldering joint between two magnets
– repairs took 14 months

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Brief History of the LHC
23rd November 2009 – first LHC proton-
proton collisions (world did not end!)
ATLAS Experiment © 2011 CERN

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LHC Run at 8 TeV in 2012
Brief History of the LHC
New results indicate that particle
discovered at CERN is a Higgs boson:
- Spin zero
- It is equal to its own antiparticle
and is mirror symmetric
- Decays as predicted by Standard
Model
Highest luminosity = 7.73·1033 cm-2s-1
Total Collisions = 1.80·1015
Recorded luminosity = 27.03 fb-1

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Higgs 4 Muons

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Higgs e+e-e+e-

34. 34

35. 35

36. 36

37. 37

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But is it THE Higgs Boson ?
=
?
Observed Higgs has poor
resolution – but it is
definitely Higgs-like
With better resolution it
could the Higgs boson could
look different

39. 39
What’s been happening in last two years, upgrading the LHC…

40. 40
LHC Run 2 at 13 TeV
LHC about to
restart after 2
year shutdown
(first collisions
end May 2015)
What’s in store
for Run 2?

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top+anti-top+(Higgs->tau+anti-tau)
Verify other Standard Model modes

42. 42
Supersymmetry (a.k.a. SUSY)
Spin 0
Bosons (like the Higgs)
SleptonsSquarks
The Generations of Smatter
~ ~ ~
~ ~ ~
~ ~ ~
~ ~ ~
s s s
s s s
s s s
s s s
Spin 1/2
Fermions
Seen Not Seen

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BOSONS
FERMIONS Gravitino Photino Gluino˜W, ˜Z

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Supersymmetric Higgs Bosons
Higgs Boson Higgsino
Higgs Boson
Higgsino
Supersymmetry (SUSY) predicts more Higgs
Bosons and spinning Higgsinos!

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46. Supersymmetry includes dark matter particles
An excellent candidate for dark
matter particle is the spin ½
partner to the photon called the
photino
˜
46

47. 47
Strong
Weak
Electromagnetic
SUSY permits a unification of three of the forces

48. 48
Allows
unification
including
gravity

49. 49
Strings moving in extra dimensions

50. 50

51. 51
The Next Director of CERN
Fabiola Gianotti, pictured here at the ATLAS detector, will
be CERN's next Director-General. Her five-year mandate will
begin on 1 January 2016

52. 52
It was the best of times [Nobel Prizes],
It was the worst of times [only Higgs discovered],
It was the age of wisdom [Standard Model complete],
It was the age of foolishness [many unanswered questions],
It was the epoch of belief [Supersymmetry…],…,
It was the season of Light [International Year of Light 2015],
It was the season of Darkness [Dark Matter and Energy],
It was the spring of hope [LHC Run 2 in Spring],
It was the winter of despair [No results last winter],
We had everything before us [new discoveries],
We had nothing before us [only Standard Model]…
Adapted from A Tale of Two Cities 1859 by Charles Dickens 1812-1870
P.S. Dickens spent Summer 1849 in Bonchurch
Summary: A Tale of Two
Standard Models ca.2015

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Thank you for your
kind attention!