Lecture 20 Nuclear Astrophysics - Heeger Group | Experimental

Experimental Nuclear Physics - PHYS741Karsten Heeger, Univ. Wisconsin 1

Lecture 20 Nuclear Astrophysics

Baryons, Dark Matter, Dark EnergyBaryogenesis, Leptogenesis

Experimental Nuclear Physics PHYS 741

[email protected]

References and Figures from:- Haxton, “Nuclear Astrophysics”- Basdevant, “Fundamentals in Nuclear Physics

mailto:[email protected]

mailto:[email protected]

Experimental Nuclear Physics - PHYS741Karsten Heeger, Univ. Wisconsin

Pheno Seminar this Friday

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Friday, November 21st, 2008Phenomenology Seminar

Methods to Detect the Cosmic Neutrino Background

Time: 2:30 pmPlace: 5280 Chamberlin HallSpeaker: Bob McElrath, CERN


Make-Up Physics 741 Lecture

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Friday, November 21st, 2008PHYS 741 Lecture

Time: 11:00 am

Place: 4274 Chamberlin Hall


Course Project

• Please send me your outline by Friday, November 21

• All talks are to be posted by Friday, December 12, 2008, 5pm CST

• Please post talks (in PDF or PPT) + references (in PDF) if you have them on a website or email them to me so that I can download them and review them before Dec 15-16.

• UW provides MyWebSpace. You can post files there.

• Final presentations will be on December 15, 4-6.30pm and December 16, 9am - noon.

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What are the characteristics of todayʼs Universe?


What are the characteristics of todayʼs Universe?

- expansion of Universe- visible Universe- baryons- dark matter- photons- neutrinos- the vacuum


Milestones in Early Universe

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at T < 100 keVdeuterium formation, followed by BBN

at T < 1 eV (380,000 yrs)photons decouple, cannot break up atomsno more free charges to scatter photonsUniverse becomes transparent

n+p ↔ d+γ p+e- ↔ H+γ

at T ~ 1 MeV (~ 1 sec)neutrinos decouplerelic neutrino spectrum left over


Cosmic Microwave Background

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Occupants of the Universe

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all data from WMAP except for - photon density (COBE)- lower limit of neutrino density (oscillation data)


Milestones in Early Universe

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at T < 100 keVdeuterium formation, followed by BBN

at T < 1 eV (380,000 yrs)photons decouple, cannot break up atomsno more free charges to scatter photonsUniverse becomes transparent

n+p ↔ d+γ p+e- ↔ H+γ

at T ~ 1 MeV (~ 1 sec)neutrinos decouplerelic neutrino spectrum left over

Relic Neutrinos


Neutrinos and Cosmology

very early universe | big bang nucleosynthesis | late time structure formation

large-scale structureWMAP

enhanced early ISW effect effect on structure formation

We see imprints of neutrino mass in the structure of todayʼs Universe …

Even small neutrino mass influences power spectrum of galaxy correlations

Neutrinos that are more massive cause more clustering on large scales.

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Cosmological Information on Neutrino Mass

very early universe | big bang nucleosynthesis | late time structure formation

large-scale structureWMAP

enhanced early ISW effect effect on structure formation

Mass limits comparable to 0νββ experiments, in the range of 0.5-1eV depending on priors for h, Ωbh2, Ωtot. → Cosmological neutrino mass limits probe Dirac and Majorana ν!

Neutrinosʼ contribution to the Universeʼs energy density Ωνh2=Σimi/92.5 eV

Combining WMAP + large scale structure (2dF, SDSS) Ωνh2<0.0076 (95% CL)

If mνe ~ mντ (degenerate neutrino species) mν < 0.55 eV (95% CL)

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Future Cosmological Constraints on Σmν

Cosmology probes important aspects of particle physics:- Neutrino mass - Dark energy equation of state

Partial degeneracy between mν, ω(neutrino mass states and dark energy equation)→ cross-correlate CMB and LSS, weak lensing, BAO measurements

Planck + LSST-like lensing survey survey ⇒ σ(Σmν)≤ 0.05 eV → probes difference between normal and inverted hierarchy

Ref: astr-ph/0603019

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Luminosity of High Redshift Objects

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observational evidence for vacuum energy -> positive vacuum energy density




Heavy Elements:0.03%

Ghostly Neutrinos: ~0.3%

Stars:0.5%

Free Hydrogen and Helium:0.4%

Dark Energy:70%

Dark Matter:25%

Matter in the Universe

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Occupants of the Universe

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all data from WMAP except for - photon density (COBE)- lower limit of neutrino density (oscillation data)


Very Early Universe

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at T 100 GeV - 10^12 GeVbaryogenesis & leptogenesis



Formative Events in the Evolution of the Universe

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Baryogenesis and Leptogenesis

to explain matter-antimatter asymmetry


Baryogenesis & Leptogenesis

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baryogenesis = hypothetical physical processes that produced an asymmetry between baryons and anti-baryons in the very early universe, resulting in the substantial amounts of residual matter that make up the universe today

leptogenesis = process which creates leptons


Baryon Asymmetry of Universe

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If CPT is violated, a baryon number can arise even in thermal equilibrium

!! The observed baryon asymmetry should

be generated dynamically after inflation

!! Matter-antimatter asymmetry can be dynamically generated in an expanding Universe if:

"! B is not conserved

"! C and CP are violated

"! departure from thermal equilibrium

Sakharov conditions

Bennet et al, AJ 2003; Spergel et al, AJ 2003

Sakharov, JETPL 1967

!! Several mechanism have been proposed to generate the baryon asymmetry of the

Universe:

Electroweak baryogenesis, GUT baryogenesis, Affleck-Dine mechanism, Leptogenesis,

Spontaneous baryogenesis, Gravitational baryogenesis, ...


Sakharov Conditions

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1967

1. baryon number violation

2. violation of C and CP

3. departure from thermal equilibrium


Mass Spectrum of Light Neutrinos

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Neutrinos !! Large scale structure data can put an upper limit on the ratio due to the neutrino free streaming effect

Bennet et al, AJ 2003

WMAP I + 2dFGRS gives

These upper limit is complemented by the results from neutrino oscillation experiments

Strumia & Vissani 2005, Fogli et al 2005

!! With these data alone, one cannot order the neutrino states by their mass in only one way.

!! The neutrino mass spectrum can be further classified into

!! The three independent mass square differences satisfy

For the case of 3 degenerate neutrino species, the WMAP limit on the sum of the neutrino masses gives

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1

2

2

mass-scale from atmospheric neutrino oscillations (~ 0.05 eV) cannot be explained in SM


See-Saw Mechanism

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Seesaw Mechanism

One of the most attractive ideas for explaining small neutrino masses is the one based on the

Minkowski, PLB 1977

Gell-Mann, Ramond & Slansky, 1979

Yanagida, 1979

Glashow, 1980

Mohapatra & Senjanovic, PRL 1980

When the heavy Majorana neutrinos decay into leptons and

Higgs scalars they violate lepton number, and the

interference between the tree-level and the one-loop amplitudes yields a non-zero CP-asymmetry. This leads to a

lepton asymmetry which is then partially converted into

baryon asymmetry by sphaleron processes.

Leptogenesis

Thanks to MIKE LESTER (and FRJ)


Light and Heavy Neutrino States

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Quantum correction

10 GeV14 M3

M2M1

Leptogenesis

10 GeV 2

m 3

m 2m 1

ν-oscillations

Seesaw


Leptogenesis

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Leptogenesis

Sphalerons

Non-perturbative effects

Violate B+L

Conserve B-L

Efficient above the EW scale

Can be converted into baryon number through

(SM)

(MSSM)

Kuzmin et al 1985

Khlebnikov et al 1985

Leptogenesis via heavy Majorana neutrino decay

Asymmetry in the lepton number

Seesaw Mechanism

Neutrino masses

Fukugita & Yanagida, PLB 1986


Heavy Neutrino Decays in Leptogenesis

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Tree level and one-loop diagrams contributing to heavy neutrinodecays whose interference leads to Leptogenesis.


Leptogenesis

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What is a sphaleron? - sphaleron is a static (time independent) solution to the electroweak field equations of the Standard Model involved in processes that violate baryon and lepton number.

- such processes cannot be represented by Feynman diagrams, and are therefore called non-perturbative.

Leptogenesis and Sphalerons- In SM, baryon number violating processes convert three baryons to three antileptons, and related processes. This violates conservation of baryon number and lepton number, but the difference B−L is conserved

- an imbalance of the number of leptons and antileptons is formed first by leptogenesis and sphaleron transitions then convert this to an imbalance in the numbers of baryons and antibaryons.

- today sphalerons are unobservably rare but have been more common at the higher temperatures of the early universe.


νR neutrinos responsible for generation of lepton asymmetry may also be responsible for smallness of the observed neutrino mass through the see-saw mechanism

Leptogenesis (Fukugita, Yanagida, 1986) • Out-of-equilibrium L-violating decays of heavy Majorana neutrinos leading to L asymmetry but leaving B unchanged.

→ Anomalous processes change BL and LL but not BL-LL. Redistribute L asymmetry. L in Universe is mostly carried by 2°K neutrinos. Observable effect is baryon asymmetry.

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Lecture 20 Nuclear Astrophysics - Heeger Group | Experimental