phys 5326 – lecture #11
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Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
1
PHYS 5326 – Lecture #11Monday, Feb. 24, 2003
Dr. Jae Yu
1. Brief Review of sin2W measurement
2. Neutrino Oscillation Measurements1. Solar neutrinos2. Atmospheric neutrinos
3. A lecture on neutrino mass (Dr. Sydney Meshkov from CalTech)
•Next makeup class is Friday, Mar. 14, 1-2:30pm, rm 200.
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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How is sin2W measured?
• Cross section ratios between NC and CC proportional to sin2W
• Llewellyn Smith Formula:
)(CC
)(CC
W4
W22
)(CC
)(NC)(
σ
σ1θsin
95
θsin21
ρσ
σR
WEMweak QIcoupling 2)3( sin)3(weakIcoupling
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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SM Global Fits with New ResultsWithout NuTeV dof=20.5/14: P=11.4%With NuTeV dof=29.7/15: P=1.3%Confidence level in upper Mhiggs limit weakens slightly.
LEP EWWG: http://www.cern.ch/LEPEWWG
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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Tree-level Parameters: and sin2W(on-shell)
• Either sin2W(on-shell) or 0 could agree with SM but both agreeing
simultaneously is unlikely
150GeV
Mln0.00032
50GeV
175GeVM0.00022θδsin
H
2
22tshell)(On
W2
0.0400.9983ρ
0.00310.2265θsin
0
W2
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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• R can be expressed in terms of quark couplings:
Model Independent Analysis
2R
2L-
--
grgR 1
XN
XN
Where
2
1
XνNσ
XNνσr
Paschos-Wolfenstein formula can be expressed as
2R
2L
νν
W22
νCC
νCC
νNC
νNC gg
r1
rRRθsin
2
1ρ
σσ
σσR
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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Model Independent Analysis
Difficult to explain the disagreement with SM by:Parton Distribution Function or LO vs NLO or Electroweak Radiative Correction: large MHiggs
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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Linking sin2W with Higgs through Mtop vs MW
150GeVM
ln0.0003250GeV
175GeVM0.00022θδsin H
2
22tshell)(On
W2
One-loop correction to sin2W
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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Oscillation Probability• Substituting the energies into the wave function:
E
tmiE
mpitt 2expcossin2exp22
121
where and .22
21
2 mmm pE
• Since the ’s move at the speed of light, t=x/c, where x is the distance to the source of .
• The probability for with energy E oscillates to e at the distance L from the source becomes
E
LmP e
222 27.1
sin2sin
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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Why is Neutrino Oscillation Important?• Neutrinos are one of the fundamental constituents in nature
– Three weak eigenstates based on SM• Left handed particles and right handed anti-particles only
– Violates parity Why only neutrinos?– Is it because of its masslessness?
• SM based on massless neutrinos• Mass eigenstates of neutrinos makes flavors to mix• SM in trouble…• Many experimental results showing definitive evidences of
neutrino oscillation– SNO giving 5 sigma results
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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Sources for Oscillation Experiments• Must have some way of knowing the flux
– Why?• Natural Sources
– Solar neutrinos– Atmospheric neutrinos
• Manmade Sources– Nuclear Reactor– Accelerator
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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Oscillation Detectors• The most important factor is the energy of neutrinos
and its products from interactions• Good particle ID is crucial• Detectors using natural sources
– Deep under ground to minimize cosmic ray background– Use Cerenkov light from secondary interactions of
neutrinose + e e+X: electron gives out Cerenkov light CC interactions, resulting in muons with Cerenkov light
• Detectors using accelerator made neutrinos– Look very much like normal neutrino detectors
• Need to increase statistics
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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Solar Neutrinos• Result from nuclear fusion process in the Sun• Primary reactions and the neutrino energy from
them are:
eLieBe 77
158B
0.867Be
1.44pep
0.42pp
E End point (MeV)ReactionName
eeDpp
eDpep
eeHeB 48 2
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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Solar Neutrino Energy Spectrum
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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Comparison of Theory and Experiments
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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Sudbery Neutrino Observatory (SNO)•Sudbery mine, Canada•6800 ft underground•12 m diameter acrylic vessel•1000 tons of D2O•9600 PMT’s
Elastic Scattering
Neutral Current
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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SNO e Event Display
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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Solar Neutrino Flux
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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SNO First Results
0.35
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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Atmospheric Neutrinos• Neutrinos resulting from the atmospheric
interactions of cosmic ray particles to e is about 2 to 1– He, p, etc + N ,K, etc
e+e+
– This reaction gives 2 and 1 e
• Expected flux ratio between and e is 2 to 1• Form a double ratio for the measurement
The
Exp
NN
NN
R
e
e
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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Super Kamiokande•Kamioka zinc mine, Japan• 1000m underground•40 m (d) x 40m(h) SS•50,000 tons of ultra pure H2O•11200(inner)+1800(outer) 50cm PMT’s•Originally for proton decay experiment•Accident in Nov. 2001, destroyed 7000 PMT’s•Dec. 2002 resume data taking
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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Atmospheric Neutrino Oscillations
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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Super-K Atmospheric Neutrino Results
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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Super-K Event Displays
Stopping 3
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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Other Experimental Results
Soudan 2 experiment
Macro experiment
Monday, Feb. 24, 2003 PHYS 5326, Spring 2003Jae Yu
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Accelerator Based Experiments• Mostly from accelerators• Long and Short baseline experiments
– Long baseline: Detectors located far away from the source, assisted by a similar detector at a very short distance (eg. MINOS: 370km, K2K: 250km, etc)
• Compare the near detector with the far detector, taking into account angular dispersion
– Short baseline: Detectors located at a close distance to the source
• Need to know flux well
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