astroparticle cosmo
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Exploring the Fundamental Particlesin the Universe
Exploring the Fundamental Particles in the Universe – p.1/29
Outline
Standard Model of Particle Physics
Beyond the Standard Model
Astroparticle Physics
Exploring the Fundamental Particles in the Universe – p.2/29
Standard Model of Particle Physics
LEPTONS : e− e+ µ− µ+ τ− τ+
νe νe νµ νµ ντ ντ
QUARKS : u u d d s s
c c b b t t
GAUGEBOSONS : γ W± Z g(8) G
HIGGSBOSON : φ
Antiparticle - same mass, opposite charge Exploring the Fundamental Particles in the Universe – p.3/29
PARTICLE DISCOVERIES
Cathode Ray Tube Electron (1897)
Compton scattering expt Photon (1923)
Cosmic Rays Positron (1932), Muon (1936)
Beta decay Electron neutrino (1956)(nuclear reactors)
Exploring the Fundamental Particles in the Universe – p.4/29
ACCELERATORS
FERMILAB pp
KEK e+e−
CERN(LHC) pp
BROOKHAVEN HeavyIonCollisions
Exploring the Fundamental Particles in the Universe – p.5/29
CERN - [27km, 100m, 11K rev/s, 1011 p per bunch]
Exploring the Fundamental Particles in the Universe – p.6/29
The LHC tunnel
Exploring the Fundamental Particles in the Universe – p.7/29
Exploring the Fundamental Particles in the Universe – p.8/29
Decaying Higgs after a p-p collision600mill/s
The decay of a Higgs particle following a collision oftwo protons (simulation). [600 million collisionseverysecond]
Exploring the Fundamental Particles in the Universe – p.9/29
PARTICLE DISCOVERIES
Accelerators Muon and Tau neutrino, Tau lepton
Up and Down quarks
s,c,b,t quarks
Gluons, W±, Z (1962-2000)
Higgs particle is not yet discovered. (LHC?)
Exploring the Fundamental Particles in the Universe – p.10/29
PARTICLE DISCOVERIES
Accelerators Muon and Tau neutrino, Tau lepton
Up and Down quarks
s,c,b,t quarks
Gluons, W±, Z (1962-2000)
Higgs particle is not yet discovered. (LHC?)Exploring the Fundamental Particles in the Universe – p.10/29
Theoretical Calculations
Quantum Mechanics Non-relativistic particlesQuantum Field Theory Relativistic particles
Represent each particle by a field
As in QM, work with a Hamiltonian (or Lagrangian)
Use perturbation theory (like in QM) to calculate howparticles decay, interact with each other, etc.
Compare theoretical and experimental results
Exploring the Fundamental Particles in the Universe – p.11/29
The Lagrangian of the Standard Model
L = −1
4W i
µνW iµν − 1
4BµνBµν − 1
4Gj
µνGjµν +θ2g2
16π2Tr
(
GjµνGjµν
)
+fDγµ(1− γ5)
[
i∂µ − g1
2τ iW i
µ − g′Y
2Bµ − gs
1
2λjGj
µ
]
fD
+fγµ(1 + γ5)
[
i∂µ − g′Y
2Bµ − gs
1
2λjGj
µ
]
f
+
∣
∣
∣
∣
(
i∂µ − g1
2τ iW i
µ − g′Y
2Bµ − gs
1
2λjGj
µ
)
φ
∣
∣
∣
∣
2
− V (φ)
−mfφf1f1 −mfφcf2f2 [i = 1, 2, 3; j = 1, 2, .., 8]
where f are fermions ( leptons and quarks), Gjµ, W j
µ andBi
µ are the strong and electroweak gauge bosonsrespectively, and φ is the Higgs boson. The Lagrangianhas SU(3)c × SU(2)L × U(1)Y mathematical symmetry,which spontaneously breaks into SU(3)c × U(1)EM.
Exploring the Fundamental Particles in the Universe – p.12/29
Unease with the Standard Model
The Standard Model of Particle Physics has 19parameters.The large number of arbitrary parameters in theStandard Model is a cause of concern.
Also neutrinos are massless in the Standard Model.(1998 - ν mass)
Some theoretical calculations of the Higgs massmake it too large (unless one carefully adjustsparameters).
GO BEYOND THE STANDARD MODEL
Exploring the Fundamental Particles in the Universe – p.13/29
Unease with the Standard Model
The Standard Model of Particle Physics has 19parameters.The large number of arbitrary parameters in theStandard Model is a cause of concern.
Also neutrinos are massless in the Standard Model.(1998 - ν mass)
Some theoretical calculations of the Higgs massmake it too large (unless one carefully adjustsparameters).
GO BEYOND THE STANDARD MODEL
Exploring the Fundamental Particles in the Universe – p.13/29
Unease with the Standard Model
The Standard Model of Particle Physics has 19parameters.The large number of arbitrary parameters in theStandard Model is a cause of concern.
Also neutrinos are massless in the Standard Model.(1998 - ν mass)
Some theoretical calculations of the Higgs massmake it too large (unless one carefully adjustsparameters).
GO BEYOND THE STANDARD MODEL
Exploring the Fundamental Particles in the Universe – p.13/29
Unease with the Standard Model
The Standard Model of Particle Physics has 19parameters.The large number of arbitrary parameters in theStandard Model is a cause of concern.
Also neutrinos are massless in the Standard Model.(1998 - ν mass)
Some theoretical calculations of the Higgs massmake it too large (unless one carefully adjustsparameters).
GO BEYOND THE STANDARD MODELExploring the Fundamental Particles in the Universe – p.13/29
Beyond the Standard Model
High Energy Theory −→ Standard Model(like Special Relativity −→ Newtonian Physics)
GRAND UNIFIED THEORIES (GUTs)(larger mathematical symmetry, neutrino mass)
SUPERSYMMETRY (controls the Higgs mass)
FERMION ←→ BOSON
BOSON ←→ FERMION
γ (PHOTON) ←→ γ (PHOTINO)
e (ELECTRON) ←→ e (SELECTRON)
Discoveries at the LHC?
Exploring the Fundamental Particles in the Universe – p.14/29
Beyond the Standard Model
High Energy Theory −→ Standard Model(like Special Relativity −→ Newtonian Physics)
GRAND UNIFIED THEORIES (GUTs)(larger mathematical symmetry, neutrino mass)
SUPERSYMMETRY (controls the Higgs mass)
FERMION ←→ BOSON
BOSON ←→ FERMION
γ (PHOTON) ←→ γ (PHOTINO)
e (ELECTRON) ←→ e (SELECTRON)
Discoveries at the LHC?
Exploring the Fundamental Particles in the Universe – p.14/29
Beyond the Standard Model
High Energy Theory −→ Standard Model(like Special Relativity −→ Newtonian Physics)
GRAND UNIFIED THEORIES (GUTs)(larger mathematical symmetry, neutrino mass)
SUPERSYMMETRY (controls the Higgs mass)
FERMION ←→ BOSON
BOSON ←→ FERMION
γ (PHOTON) ←→ γ (PHOTINO)
e (ELECTRON) ←→ e (SELECTRON)
Discoveries at the LHC?
Exploring the Fundamental Particles in the Universe – p.14/29
Beyond the Standard Model
High Energy Theory −→ Standard Model(like Special Relativity −→ Newtonian Physics)
GRAND UNIFIED THEORIES (GUTs)(larger mathematical symmetry, neutrino mass)
SUPERSYMMETRY (controls the Higgs mass)
FERMION ←→ BOSON
BOSON ←→ FERMION
γ (PHOTON) ←→ γ (PHOTINO)
e (ELECTRON) ←→ e (SELECTRON)
Discoveries at the LHC? Exploring the Fundamental Particles in the Universe – p.14/29
The Standard Model and Beyond
THE STANDARD MODEL OF PARTICLE PHYSICS
Theory: Lagrangian (Quantum Field Theory)Experiment: Cosmic Rays, Accelerators
BEYOND THE STANDARD MODEL
Grand Unified Theories (GUTs)Supersymmetry
LARGE HADRON COLLIDERExploring the Fundamental Particles in the Universe – p.15/29
What about Gravity?
CLASSICAL GRAVITY −− GENERAL THEORY OF RELATIVITY
QUANTUM GRAVITY −− ?
SUPERSTRING THEORY
Elementary particles like the photon and the electron are not point-likeobjects but are extended objects.To see the string like behaviour need very high energy probes.
Supersymmetric GUTs are included in superstring theory and theGRAVITON appears naturally in the particle spectrum. So it is aUNIFIED QUANTUM THEORY of PARTICLE PHYSICS and GRAVITY.
d > 4
Exploring the Fundamental Particles in the Universe – p.16/29
What about Gravity?
CLASSICAL GRAVITY −− GENERAL THEORY OF RELATIVITY
QUANTUM GRAVITY −− ?
SUPERSTRING THEORY
Elementary particles like the photon and the electron are not point-likeobjects but are extended objects.To see the string like behaviour need very high energy probes.
Supersymmetric GUTs are included in superstring theory and theGRAVITON appears naturally in the particle spectrum. So it is aUNIFIED QUANTUM THEORY of PARTICLE PHYSICS and GRAVITY.
d > 4
Exploring the Fundamental Particles in the Universe – p.16/29
What about Gravity?
CLASSICAL GRAVITY −− GENERAL THEORY OF RELATIVITY
QUANTUM GRAVITY −− ?
SUPERSTRING THEORY
Elementary particles like the photon and the electron are not point-likeobjects but are extended objects.To see the string like behaviour need very high energy probes.
Supersymmetric GUTs are included in superstring theory and theGRAVITON appears naturally in the particle spectrum. So it is aUNIFIED QUANTUM THEORY of PARTICLE PHYSICS and GRAVITY.
d > 4
Exploring the Fundamental Particles in the Universe – p.16/29
What about Gravity?
CLASSICAL GRAVITY −− GENERAL THEORY OF RELATIVITY
QUANTUM GRAVITY −− ?
SUPERSTRING THEORY
Elementary particles like the photon and the electron are not point-likeobjects but are extended objects.To see the string like behaviour need very high energy probes.
Supersymmetric GUTs are included in superstring theory and theGRAVITON appears naturally in the particle spectrum. So it is aUNIFIED QUANTUM THEORY of PARTICLE PHYSICS and GRAVITY.
d > 4 Exploring the Fundamental Particles in the Universe – p.16/29
Cosmology and Particle Physics
Particle Physics theories find applications inastrophysical scenarios and in the context of the EarlyUniverse. Particularly in the latter case, they allow us totest interactions of particles at very high energies.
Solar Neutrino DeficitDark MatterMatter-Antimatter Asymmetry
Exploring the Fundamental Particles in the Universe – p.17/29
Solar Neutrino Deficit
Nuclear reactions in the Sunp + p → 2H + e+ + νe
p +2 H → 3He + γ3He +3 He → 4He + 2p3He +4 He → 7Be + γ
7Be + e− → 7Li + νe
7Be + p → 8B + γ8B → 8Be∗ + e+ + νe
8Be → 4He +4 He
We detect only 1/3 of the neutrinos νe that we expect.Exploring the Fundamental Particles in the Universe – p.18/29
Neutrino Oscillations
No solution from Solar Physics.
Is something happening to neutrinos as they travel fromthe sun to the earth?
Exploring the Fundamental Particles in the Universe – p.19/29
Neutrino Oscillations
No solution from Solar Physics.
Is something happening to neutrinos as they travel fromthe sun to the earth?
Exploring the Fundamental Particles in the Universe – p.19/29
Neutrino Oscillations
Electron neutrinos emitted by the sun transform intomuon and tau neutrinos. Therefore we detect only 1/3 ofthe neutrinos emitted by the sun.
This hypothesis of neutrino oscillations has beenconfirmed by experiments. (νe ↔ νµ ↔ ντ)
Neutrino oscillations requires neutrino massessPhysics of stars tells us about fundamental particles ν
Exploring the Fundamental Particles in the Universe – p.20/29
Neutrino Oscillations
Electron neutrinos emitted by the sun transform intomuon and tau neutrinos. Therefore we detect only 1/3 ofthe neutrinos emitted by the sun.
This hypothesis of neutrino oscillations has beenconfirmed by experiments. (νe ↔ νµ ↔ ντ)
Neutrino oscillations requires neutrino massessPhysics of stars tells us about fundamental particles ν
Exploring the Fundamental Particles in the Universe – p.20/29
Dark Matter
Velocity Rotation Curves of Galaxies
Expect v ∼ 1√r, since mv2
r= GMm
r2 and M is constant.BUT ....
Exploring the Fundamental Particles in the Universe – p.21/29
Exploring the Fundamental Particles in the Universe – p.22/29
Take v ∼ constant. How can this be explained?
mv2
r= G
Mm
r2
If M(r) = Ar, then v ∼ constant.
But M(r) = Ar ⇒ matter beyond the central luminousregion which we can not see.
This non-luminous matter (does not emit or scatter light)is called DARK MATTER.
Exploring the Fundamental Particles in the Universe – p.23/29
Take v ∼ constant. How can this be explained?
mv2
r= G
Mm
r2
If M(r) = Ar, then v ∼ constant.
But M(r) = Ar ⇒ matter beyond the central luminousregion which we can not see.
This non-luminous matter (does not emit or scatter light)is called DARK MATTER.
Exploring the Fundamental Particles in the Universe – p.23/29
Take v ∼ constant. How can this be explained?
mv2
r= G
Mm
r2
If M(r) = Ar, then v ∼ constant.
But M(r) = Ar ⇒ matter beyond the central luminousregion which we can not see.
This non-luminous matter (does not emit or scatter light)is called DARK MATTER.
Exploring the Fundamental Particles in the Universe – p.23/29
DARK MATTER does not emit or scatter light so it isdifficult to detect.What is it?
Consists primarily of non-Standard Model matter –supersymmetric particles, axions, massive neutrinos, ...
High energy physics theories provide possible candidatesfor dark matter
Exploring the Fundamental Particles in the Universe – p.24/29
Matter-Antimatter Asymmetry
Observed Universe is made up of only matter.M + M → photons
Antimatter seen in laboratories since 1930s.
We believe that at early times (t < 1s) there wereequal amounts of matter and antimatter in the Universe.
WHERE DID THE ANTIMATTER GO?
Exploring the Fundamental Particles in the Universe – p.25/29
Matter-Antimatter Asymmetry
WHERE DID THE ANTIMATTER GO?
Disequilibrium in the early Universe
100 M + 100 M −→ 103 M + 101 M −→ 2 M
Possible mechanism of creating matter excess is via thedecay of GUT bosons X at t ∼ 10−34 s (T ∼ 1026K).
X −→ M
−→ M
r > r ⇒ N(M) > N(M).Particle physics theories to explain the M-A asymmetry
Exploring the Fundamental Particles in the Universe – p.26/29
Conclusion
We have a good understanding of the history andevolution of our Universe, but there are sillimportant outstanding questions – Big Bang, DarkMatter, Dark Energy
The Standard Model of Particle Physics is good butnot good enoughNeed to consider theories Beyond the StandardModel valid at higher energies
Exploring the Fundamental Particles in the Universe – p.27/29
Conclusion
Problems in Particle Physics are often linked toCosmology and vice versa
High energy particle physics theories such as StringTheory may explain the Big Bang, Supersymmetricmodels may provide the Dark Matter, GUTs mayexplain the Matter-Antimatter Asymmetry, SolarPhysics provides clues to the nature of Neutrinos
Accelerators such as the LHC will (hopefully)discover the dark matter particle
Exploring the Fundamental Particles in the Universe – p.28/29
Cosmology and Particle Physics
Books
The First Three Minutes by S. Weinberg
The Big and the Small, vol. I and II by G.Venkataraman
[email protected] the Fundamental Particles in the Universe – p.29/29