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Before Nu04 Maltoni et al 04 Large mixings: different from - PowerPoint PPT Presentation

Jan 31, 2024 •130 likes •535 views

Paris, 19 June '04 Neutrino 2004: concluding talk G. Altarelli CERN Top Highlights at Neutrino 04 Main lessons from neutrinos in recent years Impact on particle physics & cosmology Solid evidence for solar and atmosph.

  1. Paris, 19 June '04 Neutrino 2004: concluding talk G. Altarelli CERN • Top Highlights at Neutrino ‘04 • Main lessons from neutrinos in recent years • Impact on particle physics & cosmology

  2. Solid evidence for solar and atmosph. ν oscillations (+LSND unclear) Δ m 2 values fixed: Δ m 2 atm ~ 2.5 10 -3 eV 2 , Δ m 2 sol ~ 8 10 -5 eV 2 ( Δ m 2 LSND ~ 1 eV 2 ) mixing angles: θ 12 (solar) large θ 23 (atm) large,~maximal θ 13 (CHOOZ) small G. Altarelli

  3. Before Nu’04 Maltoni et al ’04 Large ν mixings: different from quarks! At first a surprise compatible with maximal G. Altarelli but not necessarily or likely so

  4. Recently great progress on Δ m 212 ! After KamLAND I & SNO(salt) Before KamLAND J. Bahcall et al Δ m 2 (eV 2 ) Nu’04: G. Altarelli Note the change KamLAND II of scale

  5. KamLAND KamLAND brings brings Δν solar down down to to earth! earth! Δν solar Gratta G. Altarelli

  6. Goswami G. Altarelli

  7. KamLAND KamLAND “L”/E “L”/E distribution: distribution: direct direct look look at at oscillations oscillations Gratta G. Altarelli

  8. Atmospheric neutrinos: SuperKamiokande L/E analysis Kearns Superkamiokande G. Altarelli

  9. L/E: stronger L/E lower bound on Δ m 2 Superkamiokande Kearns L/E G. Altarelli

  10. Important Important progress progress by by K2K K2K (bringing (bringing Δν atm down down to to earth) earth) Δν atm Nakaya G. Altarelli

  11. Goswami Recently Δ m 2 atm went down. As a consequence the upper bound on sin 2 θ 13 is weaker SK L/E results tend to improve the bound G. Altarelli

  12. Lindner G. Altarelli Present limit

  13. ν oscillations measure Δ m 2 . What is m 2 ? Δ m 2 atm ~ 2.5 10 -3 eV 2 ; Δ m 2 sun ~ 8 10 -5 eV 2 • Direct limits End-point tritium β decay (Mainz, Troitsk) m " ν e" < 2.2 eV Future: Katrin (sub-eV) m " ν µ " < 170 KeV Eitel m " ντ " < 18.2 MeV • 0 νββ m ee < 0.2 - 0.5 - ? eV (nucl. matrix elmnts) Evidence of signal? Klapdor-Kleingrothaus • Cosmology Ω ν h 2 ~ Σ i m i /94eV (h 2 ~1/2) Σ i m i � ~ 0.7-1.8-? eV (dep. on priors) WMAP, 2dFGRS... Any ν mass < 0.23-0.7 eV Why ν 's so much lighter than quarks and leptons? G. Altarelli

  14. Neutrino masses Log 10 m/eV t are really special! 10 b τ c m t /( Δ m 2 atm ) 1/2 ~10 12 s 8 µ d u Massless ν ’s? 6 e • no ν R • L conserved 4 Small ν masses? 2 • ν R very heavy WMAP 0 Upper limit on m ν • L not conserved ( Δ m 2 atm ) 1/2 ( Δ m 2 sol ) 1/2 -2 KamLAND G. Altarelli

  15. A very natural and appealing explanation: ν 's are nearly massless because they are Majorana particles and get masses through L non conserving interactions suppressed by a large scale M ~ M GUT m 2 m ~ m t ~ v ~ 200 GeV m ν ~ M M: scale of L non cons. Note: m ν ∼ ( Δ m 2atm ) 1/2 ~ 0.05 eV m ~ v ~ 200 GeV M ~ 10 15 GeV Neutrino masses are a probe of physics at M GUT ! G. Altarelli

  16. GUT's Effective couplings depend on scale M α 3 (M) The log running is computable from spectrum α 2 (M) α 1 (M) M Pl m W M GUT logM The large scale structure of particle physics: • SU(3) SU(2) U(1) unify at M GUT x x • at M Pl : quantum gravity r~10 -33 cm Superstring theory: a 10-dimensional non-local, unified theory of all interact’s The really fundamental level G. Altarelli

  17. By now GUT's are part of our culture in particle physics • Unity of forces: unification of couplings • Unity of quarks and leptons different "directions" in G • Family Q-numbers e.g. in SO(10) a whole family in 16 • Charge quantisation: Q d = -1/3-> -1/N colour • B and L non conservation ->p-decay, baryogenesis, ν masses • • • • • Most of us believe that Grand Unification must be a feature of the final theory! G. Altarelli

  18. Conceptual problems of the SM • No quantum gravity (M Pl ~ 10 19 GeV) Most clearly: • But a direct extrapolation of the SM leads directly to GUT's (M GUT ~ 10 16 GeV) M GUT close to M Pl • suggests unification with gravity as in superstring theories • poses the problem of the relation m W vs M GUT - M Pl The hierarchy Can the SM be valid up to M GUT - M Pl ?? problem Not only it looks very unlikely, but the new physics must be near the weak scale! G. Altarelli

  19. For the low energy theory: the “little hierarchy” problem: e.g. the top loop (the most pressing): m h 2 =m 2 bare + δ m h 2 t h h This hierarchy problem demands Λ ~o(1TeV) new physics near the weak scale Λ : scale of new physics beyond the SM • Λ >>m Z : the SM is so good at LEP -1/2 ~ o(1TeV) for a • Λ ~ few times G F natural explanation of m h or m W Barbieri, Strumia The LEP Paradox: m h light, new physics must be so close but its effects are not directly visible G. Altarelli

  20. Examples: SUSY • Supersymmetry: boson-fermion symm. exact (unrealistic): cancellation of δ µ 2 top loop approximate (possible): Λ ~ m SUSY -m ord Λ ~ m stop The most widely accepted • The Higgs is a ψψ condensate. No fund. scalars. But needs new very strong binding force: Λ new ~10 3 Λ QCD (technicolor). Strongly disfavoured by LEP • Large extra spacetime dimensions that bring M Pl down to o(1TeV) Elegant and exciting. Rich potentiality. Does it work? • Models where extra symmetries allow m h only at 2 loops and non pert. regime starts at Λ ~10 TeV "Little Higgs" models. Tension with EW precision tests G. Altarelli

  21. • Coupling unification: Precise SUSY fits with GUT's matching of gauge couplings at M GUT fails in SM and From α QED (m Z ), is well compatible in SUSY sin 2 θ W measured at LEP predict Non SUSY GUT's α s (m Z )=0.073±0.002 α s (m Z ) for unification (assuming desert) SUSY GUT's α s (m Z )=0.130±0.010 EXP: α s (m Z )=0.119±0.003 Langacker, Polonski Present world average Dominant error: thresholds near M GUT • Proton decay: Far too fast without SUSY • M GUT ~ 10 15 GeV non SUSY ->10 16 GeV SUSY • Dominant decay: Higgsino exchange While GUT's and SUSY very well match, (best phenomenological hint for SUSY!) in technicolor , large extra dimensions, G. Altarelli little higgs etc., there is no ground for GUT's

  22. Turner/Lahav Most of the Universe is not made up of Dark Matter atoms: Ω tot ~1, Ω b ~0.044, Ω m ~0.27 WMAP Most is Dark Matter and Dark Energy Most Dark Matter is Cold (non relativistic at freeze out) Significant Hot Dark matter is disfavoured Neutrinos are not much cosmo-relevant: Ω ν <0.015 (WMAP) SUSY has excellent DM candidates: Neutralinos (--> LHC) Also Axions are still viable (in a small mass window m~10 -5 eV) Van Bibber Identification of Dark Matter is of a task of enormous importance for particle physics and cosmology G. Altarelli

  23. Search for neutralinos Gascon Schnee Edsjo DAMA G. Altarelli

  24. Neutrino masses point to M GUT , well fit into the SUSY-GUT’s picture: indeed add considerable support to this idea. Technicolor, Little Higgs, Extra dim....: nearby cut-off. Problem of suppressing Another big plus of neutrinos is the elegant picture of baryogenesis thru leptogenesis (after LEP has disfavoured BG at the weak scale) G. Altarelli Buchmuller

  25. Baryogenesis A most attractive possibility: BG via Leptogenesis near the GUT scale T ~ 10 12±3 GeV (after inflation) Buchmuller,Yanagida, Plumacher, Ellis, Lola, Only survives if Δ (B-L) is not 0 Giudice et al, Fujii et al (otherwise is washed out at T ew by instantons) Main candidate: decay of lightest ν R (M~10 12 GeV) L non conserv. in ν R out-of-equilibrium decay: B-L excess survives at T ew and gives the obs. B asymm. Quantitative studies confirm that the range of m i from ν oscill's is perfectly compatible with BG via (thermal) LG In particular the bound m i � < 10 -1 eV Close to WMAP was derived Can be somewhat relaxed for Buchmuller, Di Bari, Plumacher G. Altarelli degenerate ν ’s. Giudice et al

  26. The scale of the cosmological constant is a big mystery. ρ Λ ∼ (2 10 -3 eV) 4 ~ (0.1mm )-4 Ω Λ ~ 0.65 In Quantum Field Theory: ρ Λ ∼ ( Λ cutoff ) 4 Similar to m ν !? If Λ cutoff ~ M Pl ρ Λ ∼ 10 123 ρ obs Exact SUSY would solve the problem: ρ Λ = 0 But SUSY is broken: ρ Λ ~ ( Λ SUSY ) 4 ~ 10 59 ρ obs ( ρ Λ ) 1/4 ~ ( Λ EW ) 2 /M Pl It is interesting that the correct order is Other problem: Why now? rad Quintessence? ρ m Λ t Now G. Altarelli

  27. The scale of vacuum energy poses a large naturalness problem! So far no clear way out: • A modification of gravity at 0.1mm? (large extra dim.) • Leak of vac. energy to other universes (wormholes)? • Anthropic principle: just right for galaxy formation (Weinberg) Perhaps naturality irrelevant also for Higgs: Arkani-Hamed, Dimopoulos; Giudice, Romanino ‘04 Split SUSY: a fine tuned light Higgs + light gauginos and higgsinos. all other s-partners heavy preserves coupling unification and dark matter Or simply a two-scale non-SUSY GUT with axions as DM G. Altarelli For ν masses all that would remain fine

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