march 24, 2007dark puzzles of the universe1 prof. bhaskar dutta and prof. teruki kamon department of...
Post on 20-Dec-2015
213 views
TRANSCRIPT
March 24, 2007 Dark Puzzles of the Universe 1
Dark Puzzles of the Universe
Prof. Bhaskar Duttaand
Prof. Teruki Kamon
Department of PhysicsTexas A&M University
Saturday Morning Physics (2007)
March 24, 2007 Dark Puzzles of the Universe 2March 24, 2007 Dark Puzzles of the Universe 2
Question
March 24, 2007 Dark Puzzles of the Universe 3
Thinking of Our Universe
March 24, 2007 Dark Puzzles of the UniverseMarch 24, 2007 Dark Puzzles of the Universe 3
My Universe
March 24, 2007 Dark Puzzles of the Universe 4
How do we measure the content of the Universe?
We look at the the oldest light which set out on its journey long before the Earth or even
our galaxy existed.
Measurement of this light tells us the story of the Universe.
This light forms the background of the Universe: Cosmic Microwave Background (CMB)
Message from the Universe
March 24, 2007 Dark Puzzles of the Universe 5
CMB was emitted when the Universe was only 380,000 years old.
The Most Distant Light
March 24, 2007 Dark Puzzles of the Universe 5
March 24, 2007 Dark Puzzles of the Universe 6
The Universe Pie
March 24, 2007 Dark Puzzles of the Universe
Today, we discuss DM.March 24, 2007 Dark Puzzles of the Universe 6
March 24, 2007 Dark Puzzles of the Universe 7
4%
The 23% is still unobserved in the laboratory.. (This new matter can not be seen visually!)We call this Dark Matter..
Content of the Universe
March 24, 2007 Dark Puzzles of the Universe 7
March 24, 2007 Dark Puzzles of the Universe 8
Examples of observations:
We know the dark matter exist.
Collision of the galaxies
Rotation curves of the galaxies
Existence of Dark Matter
March 24, 2007 Dark Puzzles of the Universe 8
March 24, 2007 Dark Puzzles of the Universe 9
4
3
2
1splitting normal matter and dark matter apart
– Another Clear Evidence of Dark Matter – (8/21/06)
Dark Matter(Gravitational Lensing)
Ordinary Matter(NASA’s Chandra XObservatory)
March 24, 2007 Dark Puzzles of the Universe
Cosmic Collision of 2 Galaxy Clusters
March 24, 2007 Dark Puzzles of the Universe 9
time
Approximately the same size asthe Milky Way
March 24, 2007 Dark Puzzles of the Universe 10
Old observation
Rotation Curves of the Galaxies
Dark Puzzles of the Universe 10March 24, 2007March 24, 2007
March 24, 2007 Dark Puzzles of the Universe 11
What is Dark Matter?
Can it be one of the known particles?11
Neutral and long-lived object
March 24, 2007 Dark Puzzles of the UniverseMarch 24, 2007 Dark Puzzles of the Universe
March 24, 2007 Dark Puzzles of the Universe 12
Building Blocks of Matter
What are the elementary particles?
March 24, 2007 Dark Puzzles of the Universe 13
Zoo: 12 Particle AnimalsThe elementary particles are fundamental building blocks of matter.
All masses in MeV.ANIMAL MASSES SCALE WITH PARTICLE MASSES
6 Typ
es o
f
Lepto
ns
6 Typ
es o
f
Quarks
March 24, 2007 Dark Puzzles of the Universe 14
Fantastic Four
NOTE : Graviton (G) ( not found) carries gravitational force.
Gluons (g) for strong forceQuarks experience them. Protons & neutrons form.
Photons () for electromagnetic force
Quarks, leptons (other than neutrinos) experience this force.
W’s for weak forces Quarks, leptons experience this force.
g W G
March 24, 2007 Dark Puzzles of the Universe 15
The Standard Model is a model which describes all these particles and 3 of 4 forces:
So, can it explain our Universe?
The Standard Model
We have confirmed the existence of SM in the laboratory experiments.
March 24, 2007 Dark Puzzles of the Universe 16
We need a new model, called Supersymmetric Standard Model or SUSY. This model has a new charge-less (neutral) particle: Neutral-ino
Dark Matter Particle?
1) What is the new model? 2) Can the neutralino be observed and consistent
with the dark matter content of the Universe?
Quarks, electron, muon, tau particles, and force carriers can not be the dark matter, since their interactions are stronger than what we expect.
Neutrinos can, but they have other problems.
x x xx x x
x x xx x x
xx
x
x
March 24, 2007 Dark Puzzles of the Universe 17
Physicists always dream about unification of all the forces.
Dream of Unification
The grand unification of the forces occur in the SUSY model.
March 24, 2007 Dark Puzzles of the Universe 18
Mirror Reflection
Ferm
ilab
Bo
sela
b
March 24, 2007 Dark Puzzles of the Universe 19
Supersymmetric Reflection
e
e
But, one of them is neutralino. This is a leading candidate for dark matter particle.
Lots of new
particles!!!!
01~
Renam
ed a
s “c
hi o
ne z
ero”
March 24, 2007 Dark Puzzles of the Universe 20
~ 0.0000001 seconds
When Were the Dark Matter Particles Created?
March 24, 2007 Dark Puzzles of the Universe 20
Now
March 24, 2007 Dark Puzzles of the Universe 21
My Universe
Thinking of Dark Matter Detection
March 24, 2007 Dark Puzzles of the UniverseMarch 24, 2007 Dark Puzzles of the Universe 21
March 24, 2007 Dark Puzzles of the Universe 22
Dark Matter particle
One type of experiment: in deep underground
How Can We See Them in the Lab?
detector
µ
March 24, 2007 Dark Puzzles of the Universe 23
One promising way: In collisions
ColliderCollider
March 24, 2007 Dark Puzzles of the Universe 24
One promising way: In particle collisions
Particle ColliderParticle Collider
➩ Tevatron and Large Hadron Collider
March 24, 2007 Dark Puzzles of the Universe 25
E = mc2 Proton and ant-proton collision can produce the Standard Model particles like heavy top quarks (~180 times heavier than a proton!)
Physics Magic: Ping-pong balls Physics Magic: Ping-pong balls Steel Balls Steel Balls
March 24, 2007 Dark Puzzles of the Universe 26
CDF DØ
Proton (p) Antiproton (p)_
Tevatron at FermilabTevatron at Fermilab
March 24, 2007 Dark Puzzles of the Universe 27
[Tevatron] proton and anti-proton collide and produce the Standard Model particles as well as New Particles. In 1995, the CDF(*) and D0 collaborations co-discovered the top quark in ~4 trillion (4,000,000,000,000) collisions.
[Q] We have 100 trillion collisons today. Can the Tevatron produce the neutralinos?
[A] May not [the neutralinos can be heavier.]
March 24, 2007 Dark Puzzles of the Universe 27
Pattern RecognitionPattern Recognition
(*) The TAMU group is one of charter members of the CDF collaboration.
March 24, 2007 Dark Puzzles of the Universe 28
The LHC at CERN, scheduled for the first proton-proton collisions in 2007 in Switzerland, will have the smashing power of 14 Tera electron Volts (14,000,000,000 eV) - far larger than any other machine ever built. Two experimental groups, called ATLAS and CMS(*), will record the first collisions by the end of 2007.
Large Hadron Collider (LHC)Large Hadron Collider (LHC)
7 times powerful than the
Tevatron
(*) The TAMU group is a member of the CMS collaboration.
March 24, 2007 Dark Puzzles of the Universe 28
March 24, 2007 Dark Puzzles of the Universe 29
Collisions as We Imagine …Collisions as We Imagine …
March 24, 2007 Dark Puzzles of the Universe 29
March 24, 2007 Dark Puzzles of the Universe 30
How do we produce the neutralinos at the LHC?
neutralinos (dark matter particles)
March 24, 2007 Dark Puzzles of the Universe 30
More Pattern RecognitionMore Pattern Recognition
We have to extract this reaction out of many trillion pp collisions.
March 24, 2007 Dark Puzzles of the Universe 31
We measure the masses (m) of the
particles at the LHC.
How do you know that the neutralinos (we will observe) at the collider are responsible for the dark matter content?
= x(m) x y / z + g x h (m) p (m) / q + r (m) x 45 / 100 + 60 x ur (m) x ty + d x s (m) + j (m) x p (m) = 0.23
We calculate the dark matter content ()in the new model of
the Universe.
March 24, 2007 Dark Puzzles of the Universe 32
So far in the laboratories we have seen the particles responsible for 4% of the universe.
The upcoming experiments will try to probe the nature of 23 % of the universe: dark matter.
Challenge:73% of the universe is still a major
puzzle.Not yet understood theoretically!
Conclusion
March 24, 2007 Dark Puzzles of the Universe 32
March 24, 2007 Dark Puzzles of the Universe 33
So far in the laboratories we have seen the particles responsible for 4% of the universe.
The upcoming experiments will try to probe the nature of 23 % of the universe: dark matter.
Challenge:73% of the universe is still a major
puzzle.Not yet understood theoretically!
Conclusion
March 24, 2007 33
TO SOLVE THE PUZZLE OF THE UNIVERSE.
March 24, 2007 Dark Puzzles of the Universe
March 24, 2007 Dark Puzzles of the Universe 34
Any Question?
March 24, 2007 34March 24, 2007 Dark Puzzles of the Universe