Theory Overview Hitoshi Murayama LBNLnu September 4 2002
Theory Overview Hitoshi Murayama LBNLnu September 4, 2002 LBNLnu Hitoshi Murayama
Disclaimer • Discussion today is limited to “neutrino properties” • Not covered: – – – High-energy neutrino astronomy Indirect dark matter search solar neutrino astrophysics Supernova neutrinos GZK neutrinos cosmic relic neutrinos • Try to raise some points for debate LBNLnu Hitoshi Murayama 2
Outline • Introduction • Current Status of Neutrino Oscillation • Future – LSND false – – LMA true – LMA false • • Future – LSND true – Absolute Mass Scale Majorana vs Dirac Conclusion LBNLnu Hitoshi Murayama 3
Current Status of Neutrino Oscillation LBNLnu Hitoshi Murayama
MNS matrix • Standard parameterization of Maki. Nakagawa-Sakata matrix for 3 generations atmospheric ? ? ? LBNLnu Hitoshi Murayama solar 5
Three-generation • Solar & atmospheric n oscillations easily accommodated within three generations • sin 22 q 23 near maximal, Dm 2 atm ~ 3 10– 3 e. V 2 • sin 22 q 12 large, Dm 2 solar ~ 3– 30 10– 5 e. V 2? • sin 22 q 13 < 0. 05 from CHOOZ, Palo Verde • Because of small sin 22 q 13, solar & atmospheric n oscillations almost decouple • Need to know the solar situation, sin 22 q 13, and mass hierarchy LBNLnu Hitoshi Murayama 6
What we learned in 2001– 2 • Atmospheric nm is lost (>10 s), converted mostly likely to nt (>99%CL) (SK, MACRO) • Solar ne is converted to either nm or nt (>5 s) (SNO) • Explanation is probably neutrino oscillation – Other possibilities: Neutrino decay, Violation of equivalence principle, spin resonant rotation, FCNC – Possible, but models tend to be ugly • Tiny neutrino mass: the first evidence for incompleteness of Minimal Standard Model LBNLnu Hitoshi Murayama 7
March 2002 April 2002 with SNO LBNLnu Hitoshi Murayama 8
Typical Theorists’ View ca. 1990 • Solar neutrino solution must be small angle MSW solution because it’s cute Most likely wrong! • Natural scale for Dm 223 ~ 10– 100 e. V 2 because it is cosmologically interesting Wrong! • Angle q 23 must be of the order of Vcb Wrong! • Atmospheric neutrino anomaly must go away because it needs a large angle Wrong! LBNLnu Hitoshi Murayama 9
MINOS (Nu. MI) OPERA/ICARUS (CNGS) • MINOS: precision measurements of (Dm 232, sin 22 q 23) • Extend reach in sin 22 q 13 by a factor ~2 below CHOOZ • OPERA/ICARUS @ CNGS: tau appearance in nm nt • Limited consistency check that there is no nm ns with large error Dm 223 1. 2 10– 3 e. V 2 OPERA 5 years LBNLnu Hitoshi Murayama 2. 4 5. 4 BG 2. 7 10. 8 53. 5 0. 75 10
MONOLITH, JHF 2 K • MONOLITH aims at verifying oscillation curves with atmospheric neutrinos • JHF 2 K: Further precision measurements of Dm 223, sin 22 q 23 LBNLnu Hitoshi Murayama 11
LSND 3. 3 s Signal • Excess positron events over calculated BG LBNLnu Hitoshi Murayama 12
Sterile Neutrino • LSND, atmospheric and solar neutrino oscillation signals • 3+1 or 2+2 spectrum? Dm 2 LSND ~ e. V 2 Dm 2 atm ~ 3 10– 3 e. V 2 Dm 2 solar < 10– 3 e. V 2 Can’t be accommodated with 3 neutrinos Need a sterile neutrino New type of neutrino with no weak interaction LBNLnu Hitoshi Murayama 13
Sterile Neutrino getting tight • 3+1 spectrum: sin 22 q. LSND=4|U 4 e|2|U 4 m|2 – |U 4 m|2 can’t be big because of CDHS, SK U/D – |U 4 e|2 can’t be big because of Bugey – Marginally allowed (90% excl. vs 99% allw’d) • 2+2 spectrum: past fits preferred – Atmospheric mostly nm nt – Solar mostly ne ns (or vice versa) – Now solar sterile getting tight due to SNO (Barger et al, Giunti et al, Gonzalez-Garcia et al, Strumia) Both scenarios disfavored at ~99% CL LBNLnu Hitoshi Murayama 14
CPT Violation? “A desperate remedy…” • LSND evidence: anti-neutrinos • Solar evidence: neutrinos • If neutrinos and antineutrinos have different mass spectra, atmospheric, solar, LSND accommodated without a sterile neutrino (HM, Yanagida) Best fit to current data (Strumia) LBNLnu Hitoshi Murayama 15
Pressing Questions • • Solution to the solar neutrino problem? How small is q 13? Mass hierarchy? CP Violation? LSND? Sterile neutrino(s)? CPT violation? Absolute mass scale? Dirac or Majorana? LBNLnu Hitoshi Murayama 16
Future – LSND false – LBNLnu Hitoshi Murayama
Mini-Boo. NE • Settles the issue of LSND evidence • Major branch point: do we need a sterile neutrino? CPT violation? • Suppose LSND disproven by Mini. Boo. NE LBNLnu Hitoshi Murayama 18
Kam. LAND • Can see the dip when Dm 2>2 10– 5 e. V 2 • Can measure mass & mixing parameters (Pierce, HM) Data/theory LBNLnu Hitoshi Murayama 19
Mini-Kam. LAND • If Dm 2>10– 4 e. V 2, oscillation washed out at Kam. LAND • Need “Mini-Kam. LAND” with L~20 km to measure Dm 2 (hep-ex/0203013) LBNLnu Hitoshi Murayama 20
If LMA confirmed. . . • Dream case for neutrino oscillation physics! • Dm 2 solar within reach of long-baseline expts • Even CP violation may be probable – neutrino superbeam – muon-storage ring neutrino factory • If LMA excluded by Kam. LAND, study of lower energy solar neutrinos crucial LBNLnu Hitoshi Murayama 21
CP Violation • Possible only if: – Dm 122, s 12 large enough (LMA) – q 13 large enough LBNLnu Hitoshi Murayama 22
superbeam • Existing proposals of neutrino superbeam (Debbie Harris@Snowmass 2001) LBNLnu Hitoshi Murayama 23
High-energy superbeam • Higher E, longer L Can study matter effect to determine the mass hierarchy (Barger, Marfatia, Whisnant@Snowmass 2001) LBNLnu Hitoshi Murayama 24
Shootout (Lindner) LBNLnu Hitoshi Murayama 25
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Solar Neutrino Spectrum Bahcall. Pinsonneault LBNLnu Hitoshi Murayama 28
VAC by seasonal variation • 7 Be neutrino monochromatic • seasonal effect probes VAC region (de Gouvêa, Friedland, HM) • Borexino crucial • Hopefully also by Kam. LAND LBNLnu Hitoshi Murayama 29
VAC by seasonal variation • Fit to seasonal variation to measure parameters Can pep n resolve degeneracy? LBNLnu Hitoshi Murayama 30
LOW by day/night effect • 7 Be neutrino monochromatic • Day/night effect probes LOW region • (de Gouvêa, Friedland, HM) • Borexino crucial • Hopefully also by Kam. LAND LBNLnu Hitoshi Murayama 31
LOW by zenith angle dependence • More information in zenith angle depend. (de Gouvêa, Friedland, HM) LBNLnu Hitoshi Murayama 32
Flavor Content • Small difference in recoil spectrum NC: e–nm, t NC+CC: e–ne • Can in principle be used to discriminate flavor of solar neutrinos modelindependently (de Gouvêa, HM) LBNLnu Hitoshi Murayama 7 Be SMA Kam. LAND 600 t*3 yrs 33
SMA by pp neutrinos • SMA: Sharp falloff in probability in the pp neutrino region the survival • Because of the condition for the level crossing • Measure the falloff Dm 2 measurement LBNLnu Hitoshi Murayama 34
Can pp neutrinos be studied? • CC+NC (electron recoil) LENS-Yb – gaseous He TPC – HERON: superfluid He (phonon & roton) – liquid Xe – GENIUS: Ge • CC (ne capture) – LENS: Yb or In – MOON: Mo LBNLnu Hitoshi Murayama 35
Case for low-energy solar n? • If Kam. LAND disproves LMA, case for lowenergy solar n is very clear: Settle solar neutrino problem! • What if Kam. LAND proves LMA? – Unitarity test using pp flux (“known” better than 1%) to study possible sterile contribution – Precision measurement of q 12 using Psurv=cos 2 q 12 for pp and Psurv=sin 2 q 12 for 8 B – Testing solar astrophysics – Too much work? LBNLnu Hitoshi Murayama 36
Case for neutrino superbeam? • If Kam. LAND confirms LMA, case for n superbeam is very clear: Find CP violation! • What if Kam. LAND disproves LMA? – sin 2 2 q 13 – sign(Dm 223) – Consistency check with mode ne nt – Too expensive? LBNLnu Hitoshi Murayama 37
Future – LSND true – LBNLnu Hitoshi Murayama
The hell breaks loose • Sterile neutrinos? – How many of them? 3? – Even with just one, there are six angles, three phases, four masses to determine • “Short” baseline experiments (~10 km) the initial target – Search for various oscillation modes with Dm 2 LSND~0. 1– 1 e. V 2 LBNLnu Hitoshi Murayama 39
The hell breaks loose • CPT Violation? – Determination of three angles, one phase, two mass-squared differences for neutrinos and antineutrinos separately – Combination of “short” and “long” baseline experiments together with low-energy solar neutrino experiments LBNLnu Hitoshi Murayama 40
Absolute Mass Scale LBNLnu Hitoshi Murayama
Cosmology vs Direct Mass Meas. • Combination of – CMBR anisotropy power spectrum (MAP/Planck) – Sloan Digital Sky Survey Sensitive down to Simni~0. 3 e. V • Tritium end point – KATRIN mne~0. 35 e. V • Both approaches require three “degenerate” neutrinos – Most theorists think unlikely… LBNLnu Hitoshi Murayama 42
Majorana vs Dirac LBNLnu Hitoshi Murayama
Neutrinoless Double-beta Decay • The only known practical approach to discriminate Majorana vs Dirac neutrinos • 0 nbb: nn ppe–e– with no neutrinos • Matrix element <mne>=Simni. Uei 2 • m 3~(Dm 223)1/2≈5 10– 2 e. V looks promising • However m 3 Ue 32<<m 3 • Upside down hierarchy an easier target • Still cancellation between m 1 and m 2 possible if Ue 12 and Ue 22 destructively interfere LBNLnu Hitoshi Murayama 44
Random 3 3 seesaw “Anarchy” (Hall, HM, Weiner; Haba, HM) LBNLnu Hitoshi Murayama 45
“Best Case” Scenario • Suppose finite neutrino mass found with Tritium end point say, all three mni~0. 5 e. V • Suppose 0 nbb found • Determine q 12 from pp solar neutrino precisely • If |<mne>|=|Simni. Uei 2| < mni but |<mne>| > mni cos 2 q 12, it demonstrates the need for a Majorana phase Leptogenesis? • Uncertainly in nuclear matrix element likely limiting factor (~2? ) LBNLnu Hitoshi Murayama 46
Conclusions • LSND false, LMA true q 13 and CP violation using superbeam, n-factory? • LSND false, LMA false low-energy solar neutrino • LSND true Combination of “short” and “long” baselines, solar neutrinos • Need absolute mass determination in any case • Need discriminate Dirac vs Majorana in any case LBNLnu Hitoshi Murayama 47
General Question • In the case of B-physics, consistency check of three-generation CKM framework tests physics beyond the standard model • Neutrino mass itself is physics beyond the standard model • Minimal extention: SM with massive neutrinos • Does the consistency check of three-generation MNS framework go beyond the SM with massive neutrinos? – Yes on possibilities of sterile neutrino – What else? R-parity violation? LBNLnu Hitoshi Murayama 48
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