Baryogenesis, Leptogenesis, and New Interactions

Home , Baryogenesis, Leptogenesis, Reionization

• The baryon (matter) asymmetry

• The Sakharov conditions

• Possible mechanisms

• A new very weak interaction

Germantown (December 3, 2003) Paul Langacker (Penn) Recent Reviews

• A. Riotto and M. Trodden, Ann. Rev. Nucl. Part. Sci. 49, 35 (1999) [arXiv:hep-ph/9901362].

• M. Trodden, Electroweak baryogenesis, Rev. Mod. Phys. 71, 1463 (1999) [arXiv:hep-ph/9803479].

• W. Bernreuther, CP violation and baryogenesis, Lect. Notes Phys. 591, 237 (2002) [arXiv:hep-ph/0205279].

• M. Dine and A. Kusenko, The origin of the matter-antimatter asymmetry, arXiv:hep-ph/0303065.

• A. D. Dolgov, Cosmological matter antimatter asymmetry and antimatter in the universe, arXiv:hep-ph/0211260.

Germantown (December 3, 2003) Paul Langacker (Penn) The baryon (matter) asymmetry

The baryon asymmetry: • Matter and antimatter are (almost) symmetric, but our part of the universe involves matter only • nB ∼ 6.1+0.7 ×10−10 (Big Bang Nucleosynthesis (BBN)), nγ −0.5 6.14 ± 0.25×10−10 (WMAP)

• nB¯ ∼ 0 (small amounts consistent with secondary production)

Germantown (December 3, 2003) Paul Langacker (Penn) − + BBN: νen ↔ e p and e n ↔ ν¯ep keep nn/np in equilibrium as long as it is rapid enough

Freezeout at T? ∼ 1 MeV, when Γweak ∼ H

nn −(mn−mp+µνe)/T? 4 = e → He (µν ∼ νe − ν¯e asymmetry) np e

4 4n4He He mass fraction: Yp = depends strongly on ξe ≡ nH nB µν /T?, weakly on η ≡ e nγ

D nB +0.7 −10 Y2 = depends on η (baryometer) ⇒ ∼ 6.1 ×10 H nγ −0.5

Germantown (December 3, 2003) Paul Langacker (Penn) Germantown (December 3, 2003) Paul Langacker (Penn) Independent determination of η from CMB ⇒nB ∼ 6.14 ± nγ 0.25×10−10

Germantown (December 3, 2003) Paul Langacker (Penn) Angular Scale 90° 2° 0.5° 0.2° 6000

TT Cross Power Spectrum 5000 Λ - CDM All Data WMAP 4000 CBI )

2 ACBAR (µK π

/2 3000 l +1)C l ( l 2000

1000

TE Cross Power 3 Reionization Spectrum ) 2 2 (µK π /2 l

1 +1)C l (

-1 0 10 40100 200 400 800 1400 Multipole moment (l)

Germantown (December 3, 2003) Paul Langacker (Penn) Germantown (December 3, 2003) Paul Langacker (Penn) • nB¯ ∼ 0 (small amounts consistent with secondary production) > ¯ • For T ∼ GeV, had nB ∼ nB¯ ∼ nγ; most BB pairs annihilated, −18 leaving small baryon excess (Otherwise, nB = nB¯ ∼ 10 nγ) n −n • Hence, need B B¯ ∼ 6×10−10 for T ∼> GeV nγ

• Neutrality: ne− ∼ nB; ne+ ∼ 0 (up to secondary production) • Large neutrino-antineutrino asymmetry possible (important for BBN), but unlikely

Germantown (December 3, 2003) Paul Langacker (Penn) (Barger, Kneller, Marfatia, PL, Steigman)

Germantown (December 3, 2003) Paul Langacker (Penn) Origin: Where did the asymmetry come from?

Prexisting asymmetry? Only if no inﬂation

Domains of matter and antimatter? • Absence of annihilation radiation implies separation > 10 Mpc (probably much stronger by CMB) • Separation of symmetric plasma? No known mechanism. −6 Causality constraints imply regions contain less than 10 M • Domains by spontaneous CP breaking possible, but hard to avoid domain wall diﬃculties

Baryogenesis: dynamical generation of asymmetry from initially symmetric conditions

Germantown (December 3, 2003) Paul Langacker (Penn) The Sakharov conditions

Basic ideas worked out by Sakharov in 1967, but no concrete model

1. Baryon number violation

2. CP violation: to distinguish baryons from antibaryons

3. Nonequilibrium of B-violating processes

Germantown (December 3, 2003) Paul Langacker (Penn) 1. Baryon number violation • Processes involving black holes • Standard model: tunneling between vacua with diﬀerent B (Rate 2 at T = 0 is ∼ e−4πsin θW /α ∼ 10−170!) • Grand uniﬁcation (GUT): new interactions lead to proton decay

Germantown (December 3, 2003) Paul Langacker (Penn) 2. CP violation: to distinguish baryons from antibaryons • Complex phases introduced by mass terms or interactions with spin-0 • Need interference of two amplitudes • Active programs in neutrino physics and heavy (b) quark decays to further explore CP violation

Germantown (December 3, 2003) Paul Langacker (Penn) Germantown (December 3, 2003) Paul Langacker (Penn) 3. Nonequilibrium of B-violating processes (or CPT violation due to expanding universe)

• Out of equilibrium decays of heavy particles (n e−m/T ) • Phase transitions • Classical ﬁeld dynamics (e.g., inﬂaton)

Germantown (December 3, 2003) Paul Langacker (Penn) Grand Uniﬁcation

Pati-Salam, 73; Georgi-Glashow, 74 > Strong, weak, electromagnetic uniﬁed at Q ∼ MX MZ • Simple group

G → SU(3)×SU(2)×U(1) MX

• Gravity not included (perhaps not ambitious enough)

• Couplings meet at MX ∼ 1014 GeV (w/o SUSY) (works much better with SUSY 16 →MX ∼ 10 GeV)

Germantown (December 3, 2003) Paul Langacker (Penn) 4 qX = 3

1 qY = 3

• q, q,¯ l, ¯l uniﬁed (in same multiplets)⇒ – Charge quantization (no U(1) factors) – Proton decay mediated by new gauge bosons, e.g. p→e+π0 (other modes in SUSY GUTS) 4 MX 30 14 – τp ∼ 2 5 ∼ 10 yr for MX ∼ 10 GeV α mp (1038 yr in SUSY, but faster p→νK¯ +)

Germantown (December 3, 2003) Paul Langacker (Penn) Possible mechanisms for generating the asymmetry

GUT baryogenesis (Yoshimura, 1979) • Out of equilibrium decay of heavy (M ∼> 1013 GeV) colored spin-0 particle H (grand uniﬁcation partner of Higgs boson):

H→q¯q¯ or ql; H¯ →qq orq ¯¯l

• Equal total rates (CPT conservation) but unequal partial rates (CP violation)

• Large enough asymmetry generated (for nonminimal model)

• B − L conserved ⇒B = L

Germantown (December 3, 2003) Paul Langacker (Penn) • Hard to combine with inﬂation unless very high reheating T • Electroweak baryon number unsuppressed at T ∼> 100 GeV (electroweak scale); wipes out asymmetry with B = L

Germantown (December 3, 2003) Paul Langacker (Penn) Leptogenesis: (Fukugita, Yanagida)

CDHSW • Seesaw model of neutrino CHORUS NOMAD

mass: mixing between light 100 KARMEN2 NOMAD LSND CHORUS and heavy neutrino Bugey BNL E776

SuperK 2 CHOO mD 10–3 Z PaloVerde mlight ∼ mD m heavy ] LMA 2

KamLAND SMA [eV where mD is similar to 2 –6

m 10 quark or charged lepton ∆ 12 LOW mass, and mheavy ∼ 10 νe↔νX νµ↔ντ GeV ν ↔ν 10–9 e τ νe↔νµ

VAC • Successful for neutrino mass scales, but mixings –12 10 –4 –2 0 2 problematic 10 10 10 10 tan2θ

Germantown (December 3, 2003) Paul Langacker (Penn) Germantown (December 3, 2003) Paul Langacker (Penn) Leptonic CP violating Phases

• Weak charge-raising current

3 µ† X 0 µ 5 0 0 µ 5 0 JW = ν¯mγ (1 − γ )em +u ¯mγ (1 − γ )dm m=1  e−  µ 5 − = (¯ν1ν¯2ν¯3)γ (1 − γ )VMNS  µ  τ −  d  µ 5 + (¯u c¯ t¯)γ (1 − γ )VCKM  s  b

u† d – VCKM = AL AL is 3×3 unitary Cabibbo-Kobayashi-Maskawa (CKM) matrix from mismatch between weak and Yukawa interactions

Germantown (December 3, 2003) Paul Langacker (Penn) ν† e – VMNS = AL AL is leptonic analogue f – AL relates weak and mass eigenstate left-handed ﬁelds

• VCKM has 3 angles and 1 CP-violating phase

• For Dirac neutrinos, VMNS also has one CP-violating phase, measurable in oscillations, e.g., νµ→νe vs ν¯µ→ν¯e

• For Majorana neutrinos, VMNS has additional factor diag (eiφ1, eiφ2, 1) (Majorana phases, due to fewer physical ﬁelds with unobservable phases) – Observable in principle in neutrinoless double beta decay, which P3 2 depends on i=1 Veimνi – Probably impossible in practice due to nuclear matrix element uncertainties (Barger, Glashow, PL, Marfatia) • Leptogenesis has 3 additional phases from Yukawa couplings to heavy right-handed neutrinos

Germantown (December 3, 2003) Paul Langacker (Penn) • Out of equilibrium decays of

Nheavy→l + Higgs 6= Nheavy→¯l + Higgs

created a lepton asymmetry • Electroweak tunneling (actually thermal ﬂuctucation) then converts some of the lepton asymmetry into a baryon asymmetry! • Diﬃculties in supersymmetric version: gravitino problem suggests

reheating temperature too low (unless Nheavy produced nonthermally)

Germantown (December 3, 2003) Paul Langacker (Penn) Electroweak baryogenesis

Utilize the electroweak (B-violating) tunneling to generate the asymmetry at time of electroweak phase transition (Kuzmin, Rubakov, Shaposhnikov)

Oﬀ the wall scenario (Cohen, Kaplan, Nelson) V eff T = T 2 > TC • Strong ﬁrst order phase transition from electroweak symmetry unbroken (massless W , Z,

fermions) to broken phase T = TC (massive W , Z, fermions) T = T < T proceeds by nucleation and 1 C 0 φ φ expansion of bubbles crit

(Figures: W. Bernreuther, hep-ph/0205279)

Germantown (December 3, 2003) Paul Langacker (Penn) • CP violation by asymmetric reflection/transmission of quarks and leptons from the wall (e.g. quarks transmitted, antiquarks reflected) • Electroweak B violation in unbroken phase outside wall > • Scenario requires strong first order transition, v(Tc)/Tc ∼ 1−1.3 and adequate CP violation in expanding bubble wall

v Wall

unbroken phase broken phase q φ = 0 q q q becomes our world

CP Γ Sph ~_ 0 CP B + L _ _ q q _ _ q q Γ Sph >> H B + L

Germantown (December 3, 2003) Paul Langacker (Penn) Implementation of “oﬀ the wall”

Standard model: no strong ﬁrst order for Mh > 114.4 GeV; CP violation too small

Minimal supersymmetric extension (MSSM): small parameter space for light Higgs and stop

NMSSM (extension to include extra Higgs ﬁelds): can have strong ﬁrst order but cosmological domain walls

Germantown (December 3, 2003) Paul Langacker (Penn) A new very weak interaction?

Extended gauge symmetry: (extra Z boson with mass ∼ TeV) (M. Cvetiˇc, PL, et al; J. Erler, PL, T. Li) • Expected in many string theories, grand uniﬁcation, dynamical symmetry breaking • Solves supersymmetric mass (µ) problem

Germantown (December 3, 2003) Paul Langacker (Penn) MZ [GeV] 2500

• Typically MZ0 > 500 − 800 Zχ GeV (Tevatron, LEP 2, WNC), 2000 −3 |θZ−Z0| < few × 10 (Z- pole) (PL, Jens Erler) 1500 (cf., MW ∼ 80 GeV, MZ ∼ 91 GeV) X

1000 • Discovery to M 0 ∼ 5−8 TeV Z oo 5 1 0 at LHC, LC

500 • Diagnostics to 1-2 TeV (asymmetries, y distributions, CDF excluded associated production, rare 0 decays) −0.01 −0.005 0 0.005 0.01 sin θ

Germantown (December 3, 2003) Paul Langacker (Penn) Tevatron (pp) Zχ √ -1 s=2 TeV, L=15fb Zψ

LHC (pp) Zη √s=14 TeV, L=100fb-1 ZLR Z √s=14 TeV, L=1 ab-1 ALR SLHC (pp) ZSSM -1 √s=28 TeV, L=100fb ZUUM

ZKK √s=28 TeV, L=1 ab-1 VLHC (pp) √s=40 TeV, L=100fb-1

√s=40 TeV, L=1 ab-1

√s=100 TeV, L=100fb-1

√s=100 TeV, L=1 ab-1

√s=200 TeV, L=100fb-1

√s=200 TeV, L=1 ab-1

1000 10000 Discovery Reach for Z' (GeV)

Germantown (December 3, 2003) Paul Langacker (Penn) Implications of U(1)0

• Solution to µ problem

• Exotics; needed for anomaly cancellation (can be consistent with gauge uniﬁcation)

• Non-standard sparticle spectrum

• Neutrino implications: Dirac, natural νR decoupling, TeV seesaw

• Dirac neutrinos and BBN (Barger, PL, Lee)

• FCNC (especially in string models) (PL, Pl¨umacher); rare B decays (Barger, Chiang, PL, LI)

Germantown (December 3, 2003) Paul Langacker (Penn) • Non-standard Higgs masses, couplings (doublet-singlet mixing) (Han, PL, McElrath)

• Enhanced possibility of EW baryogenesis (Kang, Liu, PL, Li)

Germantown (December 3, 2003) Paul Langacker (Penn) Nonstandard Higgs

(T. Han, PL, B. McElrath)

• Complex Higgs, neutralino spectrum and decays, very diﬀerent from MSSM and NMSSM because of mixing and D terms

Germantown (December 3, 2003) Paul Langacker (Penn) • 6 scalars and 4 pseudoscalars – Can have tree level CP breaking ⇒ mixing – Separate into two sectors, one decoupled – Often light scalars with signiﬁcant doublet admixture, but reduced coupling due to singlet admixture; MA < 65 GeV – Can have lightest Higgs up to 185 GeV with all couplings perturbative to MP because of D terms

2 2 2 2 2 2 Mh ≤ h v + (MZ − h v ) cos 2β 2 2 2 2 2 2 + 2gZ0v (QH2 cos β + sin βQH1) 2 4 3cos βm m ˜ m ˜ + t log t1 t2 . 2 2 2 2 v π mt

Germantown (December 3, 2003) Paul Langacker (Penn) 200

ξ H1 A1, MSSM> 0.01 175 ξ H1 A2, MSSM > 0.01 ξ H1 A2, MSSM > 0.1 ξ 150 H1 A2, MSSM > 0.5

125 H m 100

25 0 50 100 150 200 250 300 m Germantown (December 3, 2003)A Paul Langacker (Penn) 0.5

H2 0.4 Standard Model

0.3 -> ZH) (pb)

- 0.2 e + (e

σ 0.1

0 20 30 40 50 60 70 80 90 100 110 m Germantown (December 3, 2003)H Paul Langacker (Penn) Linear Collider (500 GeV) Higgsstrahlung Cross Section 70

H 60 1 H2

H3 50 Standard Model

-> ZH) (fb) 30 - e +

(e 20 σ 10

0 0 100 200 300 400 M Germantown (December 3, 2003)H Paul Langacker (Penn) Electroweak Baryogenesis with an extra U(1)0

Generates adequate baryon asymmetry (J. Kang, PL, T. Li, T. Liu)

• First phase transition breaks extended gauge symmetry, second breaks SU(2)×U(1) • Strong ﬁrst order phase transition • Explicit CP breaking in Higgs sector, diﬀerent for SU(2)×U(1) broken, unbroken • New contributions to electric dipole moments very small

Germantown (December 3, 2003) Paul Langacker (Penn) Germantown (December 3, 2003) Paul Langacker (Penn) Transition at Tc = 100 GeV, v(Tc)/Tc = 2.3

Germantown (December 3, 2003) Paul Langacker (Penn) 2.2

2.0

1.8

1.6

1.4

1.2

1.0 (z) CP 0.8 ( ) (z) CP eff h (z) or h (z) 0.6 1 2

0.4

0.2

0.0

-0.2 -30 -20 -10 0 10 20 30 z

Germantown (December 3, 2003) Paul Langacker (Penn) 0.7

0.6 n /s (10 -10) B 0.5

0.4 )

-10 0.3 /s (10

B 0.2 n

0.1

0.0

-0.1 0.0 0.2 0.4 0.6 0.8 1.0 gamma (pi)

−10 γ = explicit CP phase. Need nB/s ∼ (0.8 − 0.9)×10 . (No theory error. Parameters not optimized.)

Germantown (December 3, 2003) Paul Langacker (Penn) Conclusions

• The matter-antimatter asymmetry is one of the most important issues in particle physics and cosmology

• Several possible mechanisms: leptogenesis, electroweak baryogenesis, Aﬄeck-Dine (decay of coherent (classical) scalar quark ﬁelds in supersymmetry)

• Heavy Z0? – Very well motivated in grand uniﬁcation, strings, dynamical symmetry breaking – Many new features, including enhanced possibility of electroweak baryogenesis, non-standard Higgs, contributions to rare B decays

– Should be observable at LHC, linear collider, possibily Tevatron if it exists

Germantown (December 3, 2003) Paul Langacker (Penn)