Baryogenesis, Leptogenesis and Lepton Flavor Violation Heinrich P¨ as University of Hawaii Honolulu, HI, USA Super B Factory Workshop, Hawaii 2005 H. P¨ as Baryogenesis, Leptogenesis, LFV SuperB 2005 1
Outline • Status: Evidence for the baryon asymmetry • Requisites: Sakharov conditions for baryogenesis • Realization: Particle physics scenarios • Focus: Leptogenesis and the seesaw mechanism • Work out: LFV and the seesaw mechanism H. P¨ as Baryogenesis, Leptogenesis, LFV SuperB 2005 2
Evidence for the baryon asymmetry Observation: there are more baryons than anti-baryons in the universe • Spectrum of anti-protons in cosmic radiation (BESS/balloon in 35 km altitude) consistent with generation from cosmic primaries • no anti-nuclei found in cosmic radiation (AMS spectrometer/Discovery) H. P¨ as Baryogenesis, Leptogenesis, LFV SuperB 2005 3
Evidence for the baryon asymmetry • no aniihilation radiation detected in the local galaxy cluster • no distortion of cosmic microwave background from particle-anti-particle annihilation in the observable universe H. P¨ as Baryogenesis, Leptogenesis, LFV SuperB 2005 4
Magnitude of baryon asymmetry big bang nucleosynthesis: ∼ 0 . 1 − 180 s after big bang Synthesis p, n → D, 3 He, 4 He, 7 Li dissociated by collisions with high-energetic γ ’s ⇒ sensitive to: η B = n B − n B n γ Search for D , 3 He, 4 He, 7 Li in gas clouds and stars with small metallicity ⇒ 2 . 6 · 10 − 10 < η B < 6 . 2 · 10 − 10 S. Sarkar, astro-ph/0205116 H. P¨ as Baryogenesis, Leptogenesis, LFV SuperB 2005 5
Magnitude of baryon asymmetry Anisotropies in the CMB: Atomic synthesis ∼ 380000 y after big bang D.N. Spergel, Astrophys. J. Suppl. 148 Acustic oscillations in the early universe (2003) 175 Comparison 1st peak (fundamental wave: gravity ⇒ / ⇒ gas pressure) to 2nd peak (overtone: gravity ⇔ gas pressure) ⇒ Ratio baryons (gravity + gas pressure)/ cold dark matter (gravity) ⇒ Ratio ρ B / ρ γ ≃ 1 η B = 6 . 1 +0 . 3 − 0 . 2 · 10 − 10 ⇒ H. P¨ as Baryogenesis, Leptogenesis, LFV SuperB 2005 6
Baryon asymmetry as initial condition? Possibility: η B = 6 · 10 − 10 as initial condition? Inflationary epoch: 1 − kr 2 + r 2 dθ 2 + r 2 sin 2 θdφ 2 � ds 2 = dt 2 − R 2 ( t ) � dr 2 � R ( t ) ∝ exp( Λ / 3 t ) • ρ Λ = Λ / 8 πG : Vacuum energy of inflaton field • ⇒ flat, homogenous und empty universe! • ⇒ end of inflation: decay of inflaton field into thermal plasma • ⇒ particles and anti-particles in equal abundances • ⇒ Necessity of baryogenesis after inflationary epoch H. P¨ as Baryogenesis, Leptogenesis, LFV SuperB 2005 7
Sakharov-Bedingungen for baryogenesis • Baryon number violation: Interactions, which generate or annihilate B • Non-Equilibrium: Γ( i ( � p i ,� s i ) → f ( � p f ,� s f )) � = Γ( f ( � p f ,� s f ) → i ( � p i ,� s i )) ⇒ arrow of time • C violation: Γ( i ( � p i ,� s i ) → f ( � p f ,� s f )) � = Γ( i ( � p i ,� s i ) → f ( � p f ,� s f )) ⇒ different process rates for particles and anti-particles • CP violation: Γ( i ( � p i ,� s i ) → f ( � p f ,� s f )) � = Γ( i ( − � p i ,� s i ) → f ( − � p f ,� s f )) ⇒ different process rates for particles and anti-particles of different parities A.D. Sakharov, 1967; V.A. Kuzmin, 1970 H. P¨ as Baryogenesis, Leptogenesis, LFV SuperB 2005 8
Sakharov-Bedingungen for baryogenesis How can the Sakharov conditions be realized in a particle physics model? Baryon number violation? H. P¨ as Baryogenesis, Leptogenesis, LFV SuperB 2005 9
1st Model: GUT Baryogenesis Hypercharge Standard Model Quarks u c t d s b L L L u , R d , R c , s , R t , R b Grand Unified Theory R R SU(2) Leptons e , R µ , τ quarks and leptons in the R R same multiplet ν ν ν e µ τ L L L Unification of forces Strong Right handed neutrinos? ..."Desert"... Supersymmetry symmetry: bosons <−> fermions quarks <−> (scalar) squarks leptons <−> (scalar) sleptons bosons <−> (s=1/2) bosinos coupling unification benefits: cancels divergencies dark matter candidate necessary for gravity H. P¨ as Baryogenesis, Leptogenesis, LFV SuperB 2005 10
1st Model: GUT Baryogenesis • Baryon number violationen: GUT multiplet • Non-equilibrium decay of heavy X -bosons for M X > T universe • CP -violation: Γ( X → qq ) > Γ( X → qq ) • Problem: thermal generation of X bosons with m X ∼ M GUT → high reheating temperature after inflation T reh ∼ M GUT ≃ 10 16 GeV → powerful generation of weakly interacting superpartners (gravitinos) in SUSY scenarios → decay products prevent successful BBN Ingnatiev, Krasnikov, Kuzmin, Tavkhelidze, 1978; Yoshimura, Weinberg, 1979 H. P¨ as Baryogenesis, Leptogenesis, LFV SuperB 2005 11
2nd Model: Elektroweak baryogenesis Baryon number violation already in the Standard Model? H. P¨ as Baryogenesis, Leptogenesis, LFV SuperB 2005 12
2nd Model: Elektroweak baryogenesis Sphalerons: B violation in the Standard Model Topologically different field configurations ⇒ degenrated vacua with different baryon numbers t’Hooft 1976 T > T EW ⇒ Transitions between vacua, Baryon number violation Kuzmin, Rubakov, Shaposhnikov, 1985 H. P¨ as Baryogenesis, Leptogenesis, LFV SuperB 2005 13
2nd Model: Elektroweak baryogenesis Electroweak phase transition ∼ 10 − 10 s after big bang Condensation of the Higgs field: � φ � = 0 → � φ � = v ( T < T c ) ⇒ Mass generation, CP violation Non-equilibrium: analogy water-steam transition Requirement: 1st order transition ⇔ competing ground states dependent of Higgs potential ⇒ depending on Higgs self interaction √ λ ⇒ m H = v ( T = 0) 2 λ < 70 GeV m H > 114 GeV bei LEP too small! H. P¨ as Baryogenesis, Leptogenesis, LFV SuperB 2005 14
3rd Modell: Leptogenesis Combination of Non-equilibrium decay and baryogenesis at low energies? H. P¨ as Baryogenesis, Leptogenesis, LFV SuperB 2005 15
3rd Modell: Leptogenesis Neutrino mass generation in the seesaw mechanism Motivation: m ν ≪ m u,d,e , Standard Model: m ν ≡ 0 , since no right-handed neutrino + h ( ) 0 h Assumption: ∃ right-handed neutrino N R : “Normal” Dirac mass term m D ν L N R ( ) L ν ν R e However: N R is a SM singlet! ⇒ Majorana mass term N R M R ( N R ) C , M R ≫ m D ν R C ν L E. Majorana 1937 ν c m D � � � � � � 0 ν L m D+M ≡ L m D M R ( N R ) c ( N R ) m D ≪ m R ⇒ m light ≃ − ( m D ) 2 /M R ≪ m D ⇒ ∃ right-handed Neutrino N R with L violating mass M R ∼ 10 14 GeV H. P¨ as Baryogenesis, Leptogenesis, LFV SuperB 2005 16
3rd Modell: Leptogenesis N R decays in the early universe • Non-equilibrium decay of heavy neutrinos for M R > T universe • CP violation Γ( N R → ¯ h + ¯ ν L ) > Γ( N R → h + ν L ) ⇒ L -violation • B -violation: L -violation + B + L violating sphaleron processes → B violation ⇒ Relations to neutrino physics + lepton flavor violation! Fukugita, Yanagida, 1986 H. P¨ as Baryogenesis, Leptogenesis, LFV SuperB 2005 17
3rd Modell: Leptogenesis ν R sector 3 Majorana masses 6 R−Matrix elements seesaw−Relation 18 parameters ν L sector 3 mixing angles: θ sun , , θ atm θ 13 1 Dirac phase 2 2 2 2 ∆ m : ∆ m ∆ m sun atm 2 Majorana phases , 1 absolute mass H. P¨ as Baryogenesis, Leptogenesis, LFV SuperB 2005 18
LFV processes ν Y ν ∝ ( m D ) 2 ∝ M R ( ∼ M 3 ) Inverting the seesaw matrix: Y † ⇒ Look for processes ∝ Y † ν Y ν ⇒ Lepton Flavor violating corrections to slepton masses! ~ h 2 h 2 ~ ~ ~ ~ l l i j l l i j ~ ν R ν R γ 2 ~ ( m ) δ γ χ µ e L ~ ~ l l µ e µ e µ e ~ ~ ν µ ν e ~ 2 χ o ( m ) δ L µ e H. P¨ as Baryogenesis, Leptogenesis, LFV SuperB 2005 19
Br ( µ → eγ ) and Br ( τ → µγ ) SUSY scenario SPS1, m 1 < 0 . 03 eV PDG: Br ( µ → eγ ) < 1 . 2 · 10 − 11 (90% C.L. ) ⇒ M R < 10 14 − 10 15 GeV Br ( τ → µγ ) < 10 − 8 (90% C.L. ) : determination accuracy factor 2! F. Deppisch, H. P¨ as, A. Redelbach, R. R¨ uckl, Y. Shimizu, Eur.Phys.J. C28 (2003) 365-374 H. P¨ as Baryogenesis, Leptogenesis, LFV SuperB 2005 20
Gravitino bound and R-matrix elements mSUGRA problem: overabundance of gravitinos for T R > 10 10 GeV ( m 3 / 2 ≃ 1 TeV) ⇒ M 1 < 10 T R < 10 11 GeV ⇒ x 2 , 3 ≃ 0 , π, 2 π Contours: y i = 0 . 1 , best fit ν L F. Deppisch, H. P¨ as, A. Redelbach, R. R¨ uckl, in preparation H. P¨ as Baryogenesis, Leptogenesis, LFV SuperB 2005 21
Br ( µ → eγ / Br ( τ → µγ and x 1 Strong variation of Br ( µ → eγ ) /Br ( τ → µγ ) with x 1 SuperB: Br ( τ → µγ ) ≃ 10 8 ⇒ Sensitivity: Br ( µ → eγ ) /Br ( τ → µγ ) < O 10 − 3 F. Deppisch, H. P¨ as, A. Redelbach, R. R¨ uckl, in preparation H. P¨ as Baryogenesis, Leptogenesis, LFV SuperB 2005 22
Recommend
More recommend
