neutrino physics
Download
Skip this Video
Download Presentation
Neutrino Physics

Loading in 2 Seconds...

play fullscreen
1 / 46

Neutrino Physics - PowerPoint PPT Presentation


  • 198 Views
  • Uploaded on

Neutrino Physics. Neutrino mass and mixing No neutrinoless double beta decay. Nishikawa @ XXXIV International Meeting on Fundamental Physics April 3-7,2006. Neutrinos are Everywhere. Big Bang: They are still left over: ~300 neutrinos per cm 3 Natural sources

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Neutrino Physics' - lynn


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
neutrino physics

Neutrino Physics

Neutrino mass and mixing

No neutrinoless double beta decay

  • Nishikawa
  • @XXXIV International Meeting
  • on Fundamental Physics
  • April 3-7,2006
neutrinos are everywhere
Neutrinos are Everywhere
  • Big Bang:
    • They are still left over: ~300 neutrinos per cm3
  • Natural sources
    • Sun : 1012 of neutrinos /sec /cm2
    • Atmosphere : 103 high energy neutrinos /sec/m2
    • Reactor : 1020 neutrinos/GWth
  • Weak:
    • Need to stack up lead shield up to three light-years to stop them
  • Light
    • Twelve orders of magnitudes below Mt or weak scale10
slide3

Brief history

    • 1930 Pauli’s neutrino hypothesis
    • 1934 Fermi theory of weak interaction
    • 1956 Neutrino observation by Reines and Cowan
  • Neutrinos are left handed

q-t puzzle and parity

    • 1957 Parity violation by Wu et.al.

Helicity of neutrino measured by M.Goldhaber et.al.

    • 1958 V-A (Sudarshan & Marshak, Feynman & Gell-Mann) Current-current formulation
  • Intermediate Vector Boson (W) hypothesis
    • 1960 Two neutrino hypothesis (Lee, Yang)
    • 1968 Solar neutrino problem (Ray Davis)
  • Electro-weak unification
    • 1967 Weinberg, Salam, Glashow
    • ‘t Hooft’s proof
    • 1973 Discovery of Weak Neutral Current (Gargamelle)
    • 1983 Observation of Z,W
conclusion of this series of talks

Conclusion of this series of talks

Experimental evidences for the following summary

slide5

Two mass eigen-states haveDm2~8x10-5 eV2

  • Define n1, n2 such that
  • mn2 > mn1
  • Solarn MSW in neutrino (not anti-neutrino)
  • n1 is the largest component inne
  • Third mass eigen-sate (n3) isseparated byDm2~ ±3x10-3 eV2
  • Smallne component inn3 (n3 consists ofnm, nt, almost 50;50)which is larger in nt ? (q23<p/4 ?)
  • neutrino mass and charged lepton mass ordering
  • same or inverted

8

atm.

3x10-3eV2

issues about neutrinos for coming years
Issues about neutrinos for coming years?

Neutrino-lessbb

  • What is Neutrino?Tiny mass (~x 10-10 ) of q,l±
    • Majorana : Majorana and Dirac masses co-exist
      • See Saw mn~ m2/M (M~coupling unification scale)
      • neutrino = antineutrino DL= 2 units
    • Dirac : ~ quarks, charged leptons
      • very very weakly coupled RH
  • Different patterns of mixings in quarks and in leptons
    • Masses and interactions (transitions among elementary particles)
    • Particle and anti-particle distinction, especially in pure leptonic process
  • Baryon- Anti-Baryon asymmetry in Universe ?

NeutrinoOscillation

contents 1
Contents-1
  • Experimental achievements
  • What are neutrinos?
  • Their interactions?
  • Imaging type water Cherenkov detector (Super-Kamiokande)
helicity of neutrino v a
Helicity of neutrino (V-A)
  • Parity

LH

RH

direction of motion

direction of motion

P

Maximum parity violation means a possibility

where only one of those state exist in nature

direction of spin = direction of advancement of right handed screw

neutrinos must be massless
Neutrinos must be Massless
  • All neutrinos left-handed  massless
  • If they have mass, can’t go at speed of light.
  • Now neutrino right-handed??

 contradiction  can’t be massive

anti neutrinos are right handed

nCR

Anti-Neutrinos are Right-handed
  • CPT theorem in quantum field theory
    • C: interchange particles & anti-particles
    • P: parity (r → -r)
    • T: time-reversal (t → -t)
  • State obtained by CPT from nL must exist: nCR
  • Lorenz transformed state

nR (Lorenz)

nCR = nR ?

standard model
Standard Model

Finite mass of neutrinos imply the Standard Model is incomplete!

  • Not just incomplete but probably a lot more profound
    • New kind of field (Majorana : nCR=nR)
    • Very small RH interaction (Cannot produced by interaction)
intermediate vector boson and m decay
Intermediate Vector Boson and m-decay
  • Feinberg’s argument (1958)
  • V-A current-current formulation suggest W± analog to g
  • Pontecorvo (1959) Schwartz (1960) idea of high energy neutrino beam

nm = ne ?

slide15

DONUT

FNAL E872 Beam dump beam

Status:

406 neutrino interaction analyzed.

7 ntCCevent detected

On-going :

Component analysis of the prompt neutrino beam

νe:νμ:ντ

Interaction Point

t

Decay Point of t

neutrino

Vertex detection :

Neutrino interaction and decay of short lived particles

Reject Low momentum tracks

(114 tracks remained)

Reject passing

through tracks

(420 tracks remained)

All tracks in the Scanning region (4179 tracks)

Detection of ντCCin DONUT

the number of neutrinos collider experiments

N = 2.984 0.008

The Number of Neutrinoscollider experiments
  • most precise measurements come from Z e + e
  • invisible partial width, inv, determined by subtracting measured visible partial widths (Z decays to quarks and charged leptons) from the Z width
  • invisible width assumed to be due to N
  • Standard Model value (  l)SM = 1.991  0.001 (using ratio reduces model dependence)
charged current interaction

W

Charged current interaction

Transformation between pair of particles, differ by unit charge

neL nmL ntL uL cL tL

t3=1/2

(nR nR nR)

uR cR tR

eR mR tR

dR sR bR

eL mL tL dL sL bL

t3=-1/2

mixing exist (CKM)

  • Coupling constant(GF) is universal for all particles
  • Left-handed particles form weak isospin-doublets
  • All right-handed particles have no charged current interaction
  • (even if they exist in nature) iso-singlets
  • Interaction is mediated by W intermediate vector boson

GF =

slide19

l

nl

W

e

ne

nl + n→ l(-) + p

nl + p → l(+) +n

GF : Fermi coupling constant

isotropic in cms

~10-41・Encm2

Enth~10GeVform

nl+e → ne+l

g

l:Forward peak

qn-e small

g

~10-38・En cm2

Complication by free, almost free nucleons

form factors, Nuclear effect(Pauli blocking) H2O D2O CH

quasi elastic scattering cross sections
Quasi-elastic scattering cross-sections

m-

nm

W

p

Cross-section (nm)

10-38cm2

magenta Old MC

red new MC

  • Two form factors
    • MV fixed by e.m. (CVC)
    • Axial V form factor

n

s/En (10-38cm2/GeV)

1 10 100 GeV

data on charged current processes
Data on charged current processes
  • Not well known
  • Especially 2~3 GeV
  • must be determined internally
neutral current interaction

neL nmL ntL eL mL tL

uL cL tL dL sL bL

(nR nR nR)

eR mR tR

uR cR tR

dR sR bR

gL,R

nl

Neutral current interaction

nl

Z

e(N)

e(N)

gL,R

g=T3 - sin2qW·Q

neutrino oscillation
Neutrino oscillation

n1

n2

nt

nm

  • Inteferometry (i.e., Michaelson-Morley)
    • Coherent source
    • Interference (i.e., large mixing angles)
    • Need long baseline for small Dm2
  • Neutrino mass must be non-zero, if oscillation occurs
the hamiltonian
The Hamiltonian
  • The Hamiltonian of a freely-propagating massive neutrino
  • But in quantum mechanics, mass is a matrix in general. 22 case:
two neutrino oscillation
Two-Neutrino Oscillation
  • When produced (e.g., p+m+nm), neutrino is of a particular type
  • At time t
  • No longer 100% nm, partly nt!
  • “Survival probability” for nm after t
three flavor mixing in lepton sector

ne

nm

nt

Three Flavor Mixing in Lepton Sector

mass eigenstates

Weak eigenstates

m1

m2

m3

cij = cosqij, sij=sinqij

q12, q23, q13

+ d (+2 Majorana phase)

Dm122, Dm232, Dm132

matter effect msw effect
Matter effect MSW effect
  • Neutrinos propagate in matter receive a refractive effect due to their interaction (extra energy V, the energy E, momentum k’) with matter

The refractive index n is defined by

E2=k2+m2the dispersion relation in vacuum and k’=nk

n=1-EV/k2

ne electron density

msw effect ii
MSW effect (II)

- for anti-neutrino

Dn=1-n ~7.6 x 10-19 (r/100g cm-3)(E/10MeV)-1 for ne small for nm,t

velocity changes == effective mass changes in matter

(r=100g/cc at the center of Sun)

Active neutrinos by interaction with p,n

Can distinguish ‘active’ and ‘sterile’ neutrinos

effective mass in matter
effective mass in matter

Schrodinger eq.

Hamiltonian

Effective mass difference of ne and nm,tin matter by Ve

mass difference and mixing angle in matter
Mass difference and mixing angle in matter

A change sign for anti-neutrinos

Ne= 6x1025 /cc = 6 x 10-14 /fm3 for r=100g/cc

GF~10-5 GeV-2 (0.2GeV·fm)3 =8 x 10-8 GeV fm3

A =10-2 En (GeV) eV2

slide32

MSW in the Solar neutrinos

In(Dm2)

m2

m1

In(sin2q)

Also Day Night!

msw for sterile
‘MSW’ for sterile

Large Dm2 →(E >10 GeV in earth) Dm2~A

matter effect in the earth for sterile neutrinos
matter effect in the earth for sterile neutrinos

PC, Evis>5GeV

<Eν>~25GeV

up/down ratio

ns

ns

Z

νμーνs

νμーνs

n

νμーντ

νμーντ

n

up through going μ

<Eν>~100GeV

vertical/horizontal ratio

detectors for neutrino oscillation experiments
Detectors for Neutrino Oscillation Experiments
  • Massive
  • Neutrino oscillation is the oscillation between different flavors
    • e, μ, τidentification by charged current interactions
    • target and sensor must be combined
  • Only Flux(En) x s(En) will be measured
    • En, L must be known event-by event to get Dm2
    • Two distances if possible
particle identification
Particle identification
  • m-ID
    • minimum ionizing particle with long range R500g/cm2/GeV
  • e-ID
    • showering particle, large g (TRD), E/p1(with magnet)
  • t-ID
    • short decay length
    • isolated hadronic activity (charm)
    • t→enn t→mnn, t→nt +hadrons
inside super k
Inside Super-K

Kamiokande

super kamiokande 1996

41.4m

40m

Super-Kamiokande (1996)
  • 1996-
  • 50000ton water
  • 11146 50cmf PMT (40% photo coverage)
  • 1000m underground
  • Min det. energy ~ 5 MeV
  • Inner and outer
principle of the technique

qc

dN 2pasin2qc

dxdl l2

=

Principle of the technique
  • Cherenkov radiation: electromagnetic radiation in a medium with refractive index n if nb>1 (b=v/c)
    • cosqc = 1/nb,
    • where N is the number of emitted Cherenkov photons with wavelength l, dx is the particle’s path length, and a =1/137
    • Cherenkov photons are detected with a large number of photomultiplier tubes (PMT)
  • For Super-K, qC = 42deg (b = 1), good at simple geom.
  • N(photo e.) ~ 6 / Mev e- : about 1/1000 of scintillator
  • Attenuation length can be attained upto ~100m
  • P(threshold)~1.2 GeV/c for protons
slide42

Cherenkov light

Charged particle

particle id e m in single ring events
Particle ID (e & m)(in single ring events)
  • An experiment with test beams confirmed the particle ID

capability (PL B374(1996)238)

K2K 98% nm beam

near detector

m

e

m

e

Atm. data

Excellent for low multiplicity

Low energy

ad