Neutrino Oscillation Hitoshi Murayama Berkeley PRCUS Meeting IHEP

Neutrino Oscillation Hitoshi Murayama (Berkeley) PRC-US Meeting @ IHEP June 12, 2006 Murayama, IHEP, June 12, 2006

Outline • • Past: Why Neutrinos? Present: Era of Revolution Future Conclusion Murayama, IHEP, June 12, 2006 2

Past Why Neutrinos? Murayama, IHEP, June 12, 2006

Interest in Neutrino Mass • So much activity on neutrino mass already. Why am I interested in this? Window to (way) high energy scales beyond the Standard Model! • Two ways: – Go to high energies – Study rare, tiny effects Murayama, IHEP, June 12, 2006 4

Rare Effects from High-Energies • Effects of physics beyond the SM as effective operators • Can be classified systematically (Weinberg) Murayama, IHEP, June 12, 2006 5

Unique Role of Neutrino Mass • Lowest order effect of physics at short distances • Tiny effect (m /E )2~(0. 1 e. V/Ge. V)2=10– 20! • Interferometry (i. e. , Michaelson-Morley) – Need coherent source – Need interference (i. e. , large mixing angles) – Need long baseline Nature was kind to provide all of them! • “neutrino interferometry” (a. k. a. neutrino oscillation) a unique tool to study physics at very Murayama, IHEP, June 12, 2006 high scales 6

Ubiquitous Neutrinos They must have played some important role in the universe! Murayama, IHEP, June 12, 2006 7

Present Era of Revolution Murayama, IHEP, June 12, 2006

The Data Evidence for oscillation: • “Indisputable” – Atmospheric – Solar – Reactor • “strong” – Accelerator (K 2 K) And we shouldn’t forget: • “unconfirmed” – Accelerator (LSND) Murayama, IHEP, June 12, 2006 9

Super. Kamiokande Atmospheric disappear 2/dof=839. 7/755 (18%) m 2=2. 5 10 -3 e. V 2 sin 22 =1 Downwards ’s don’t disappear 1/2 of upwards Murayama, IHEP, Junedisappear 12, 2006 ’s do 10

SNO Solar transform in flavor 2/3 of e’s Murayama, IHEP, June 12, 2006 11

Kam. LAND Reactor neutrinos do oscillate! Proper time L 0=180 km Murayama, IHEP, June 12, 2006 12

What we learned • Lepton Flavor is not conserved • Neutrinos have tiny mass, not very hierarchical • Neutrinos mix a lot the first evidence for demise of the Minimal Standard Model Very different from quarks Murayama, IHEP, June 12, 2006 13

Typical Theorists’ View ca. 1990 • Solar neutrino solution must be small angle Wrong! MSW solution because it’s cute • Natural scale for m 223 ~ 10– 100 e. V 2 Wrong! because it is cosmologically interesting Wrong! • Angle 23 must be 23 ~ Vcb =0. 04 • Atmospheric neutrino anomaly must go Wrong! away because it needs a large angle Murayama, IHEP, June 12, 2006 14

The Big Questions • • • What is the origin of neutrino mass? Did neutrinos play a role in our existence? Did neutrinos play a role in forming galaxies? Did neutrinos play a role in birth of the universe? Are neutrinos telling us something about unification of matter and/or forces? • Will neutrinos give us more surprises? Big questions tough questions to answer Murayama, IHEP, June 12, 2006 15

Immediate Questions • • Dirac or Majorana? Absolute mass scale? How small is 13? CP Violation? Mass hierarchy? Is 23 maximal? LSND? Sterile neutrino(s)? CPT violation? Murayama, IHEP, June 12, 2006 16

Future Murayama, IHEP, June 12, 2006

Immediate Questions • • Dirac or Majorana? Absolute mass scale? How small is 13? CP Violation? Mass hierarchy? Is 23 maximal? LSND? Sterile neutrino(s)? CPT violation? Murayama, IHEP, June 12, 2006 18

Immediate Questions • • Dirac or Majorana? Absolute mass scale? How small is 13? CP Violation? Mass hierarchy? Is 23 maximal? LSND? Sterile neutrino(s)? CPT violation? Murayama, IHEP, June 12, 2006 19

LSND doesn’t fit into the picture • Sterile neutrino (3+1) barely consistent with short-baseline data • Sterile neutrinos are strongly constrained by WMAP+SDSS: m<0. 26 e. V (95%CL) WMAP 3 yr+SDSS (Seljak, Slosar, Mc. Donald) • CPT violation without sterile neutrino excluded by SNO+Kam. LAND HM, Pierce Murayama, IHEP, June 12, 2006 20

The hell breaks loose • Mini-Boo. NE will open the box this summer • If Mini-Boo. NE confirms LSND, it is hard to understand what is going on, because there is currently no simple way to accommodate LSND result with other neutrino data – – Multiple sterile neutrinos? 3+2? Sterile neutrino and CPT violation? Mass varying neutrinos? Something even more wild and wacky? Murayama, IHEP, June 12, 2006 21

What it would take • We will need neutrino “oscillation” experiments with multiple baselines, multiple modes – E~10 Ge. V, L~10 km, looking for appearance – Redo CDHSW ( disappearance experiment with L=130 & 885 m, E=19. 2 Ge. V) – E~1 Ge. V, L~1 km, looking for oscillatory behavior and CP violation in e , or better, e – Some in the air, some in the earth – Probably more – Muon source would help greatly Murayama, IHEP, June 12, 2006 22

Immediate Questions • • Dirac or Majorana? Absolute mass scale? How small is 13? CP Violation? Mass hierarchy? Is 23 maximal? LSND? Sterile neutrino(s)? CPT violation? Murayama, IHEP, June 12, 2006 23

T 2 K (Tokai to Kamioka) Murayama, IHEP, June 12, 2006 24

Immediate Questions • • Dirac or Majorana? Absolute mass scale? How small is 13? CP Violation? Mass hierarchy? Is 23 maximal? LSND? Sterile neutrino(s)? CPT violation? Murayama, IHEP, June 12, 2006 25

LMA confirmed by Kam. LAND • Dream case for neutrino oscillation physics! • m 2 solar within reach of long-baseline expts • Even CP violation may be probable • Possible only if: – m 122, s 12 large enough (LMA) – 13 large enough Murayama, IHEP, June 12, 2006 26

13 decides the future • The value of 13 crucial for the future of neutrino oscillation physics • Determines the required facility/parameters/baseline/energy – sin 22 13>0. 01 conventional neutrino beam – sin 22 13<0. 01 storage ring, beam • Two paths to determine 13 – Long-baseline accelerator: T 2 K, NO A – Reactor neutrino experiment: 2 CHOOZ, Daya Bay Murayama, IHEP, June 12, 2006 27

NO A Fermilab to Minnesota NO A MINOS 25 kt L=810 km 32 -plane block Admirer Murayama, IHEP, June 12, 2006 28

Daya Bay Far site 1600 m from Ling Ao 2000 m from Daya Overburden: 350 m m 0 1 9 Empty detectors: moved to underground halls through access tunnel. Filled detectors: swapped between underground halls via horizontal tunnels. Ling Ao Near 500 m from Ling Ao Overburden: 98 m Mid site ~1000 m from Daya Overburden: 208 m 730 m 570 230 m 290 m Entrance portal Ling Ao-ll NPP (under const. ) m Ling Ao NPP Daya Bay Near 360 m from Daya Bay Overburden: 97 m Daya Bay NPP Total tunnel length: ~2700 m Murayama, IHEP, June 12, 2006 29

3 sensitivity on sin 2 2 13 Murayama, IHEP, June 12, 2006 30

T 2 K vs NO A • LBL e appearance • Combination of – sin 22 13 – Matter effect – CP phase 95%CL resolution of mass hierarchy Murayama, IHEP, June 12, 2006 31

Accelerator vs Reactor w 100 t (3 yrs) +T 2 K (5 yr, n-only) 90% CL Reactor w 10 t (3 yrs) +T 2 K 90% CL Reactor experiments can help in Resolving the 23 degeneracy (Example: sin 22 23 = 0. 95 ± 0. 01) Reactor w 100 t (3 yrs) + Nova only (3 yr + 3 yr) Reactor w 10 t (3 yrs) + Nova 90% CL Mc. Connel & Shaevitz, hep-ex/0409028 Murayama, IHEP, June 12, 2006 32

My prejudice • Let’s not write a complicated theory • The only natural measure for mixing angles is the group-theoretical invariant Haar measure • Kolmogorov–Smirnov test: 64% • sin 2 2 13>0. 04 (2 s) • sin 2 2 13>0. 01 (99%CL) 13 Murayama, IHEP, June 12, 2006 12 23 33

Immediate Questions • • Dirac or Majorana? Absolute mass scale? How small is 13? CP Violation? Mass hierarchy? Is 23 maximal? LSND? Sterile neutrino(s)? CPT violation? Murayama, IHEP, June 12, 2006 34

What about the Big Questions? • • • What is the origin of neutrino mass? Did neutrinos play a role in our existence? Did neutrinos play a role in forming galaxies? Did neutrinos play a role in birth of the universe? Are neutrinos telling us something about unification of matter and/or forces? • Will neutrinos give us more surprises? Big questions tough questions to answer Murayama, IHEP, June 12, 2006 35

Seesaw Mechanism • Why is neutrino mass so small? • Need right-handed neutrinos to generate neutrino mass , but R SM neutral To obtain m 3~( m 2 atm)1/2, m. D~mt, M 3~1014– 1014 Ge. V Murayama, IHEP, June 12, 2006 36

Leptogenesis • You generate Lepton Asymmetry first. (Fukugita, Yanagida) • Generate L from the direct CP violation in right-handed neutrino decay • L gets converted to B via EW anomaly More matter than anti-matter We have survived “The Great Annihilation” • Despite detailed information on neutrino masses, it still works (e. g. , Bari, Buchmüller, Plümacher) 37

~R Origin of Universe – slowly rolls down the potential – oscillates around it minimum – decays to produce a thermal bath • The superpartner of right-handed neutrino fits the bill • When it decays, it produces the lepton asymmetry at the same time (HM, Suzuki, Yanagida, Yokoyama) • Decay products: supersymmetry and hence dark matter Neutrino is mother of the Universe? size of the universe amplitude • Maybe an even bigger role: inflation • Need a spinless field that Murayama, IHEP, June 12, 2006 38

LHC/ILC may help • LHC finds SUSY • ILC measures masses precisely • If both gaugino and sfermion masses unify, there can’t be new particles < 1014 Ge. V except for gauge-singlets Murayama, IHEP, June 12, 2006 39

Plausible scenario • 0 found • Lepton flavor violation limits ( e , e • LHC discovers SUSY conversion, etc) • ILC shows unification of improve gaugino and scalar masses • Tevatron and EDM (e and • Dark matter concordance n) exclude Electroweak between collider, Baryogenesis cosmology, direct • CMB B-mode polarization detection gives tensor mode r=0. 16 • CP in -oscillation found If this happens, we will be led to believe seesaw+leptogenesis (Buckley, HM) Murayama, IHEP, June 12, 2006 40

Conclusions • Neutrino oscillation a unique tool to probe (very) high-energy world • Era of revolution • sin 2 2 13 decides the future • My prejudice: 13 is “large” • Reactor & accelerator LBL expts complementary • To understand “big questions” we need a diverse set of experiments Murayama, IHEP, June 12, 2006 41

The I visibles Murayama, IHEP, June 12, 2006 42

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