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PHYS 5326 Lecture #11Monday, Feb. 24, 2003Dr. Jae YuBrief Review
of sin2qW measurementNeutrino Oscillation MeasurementsSolar
neutrinosAtmospheric neutrinosA lecture on neutrino mass (Dr.
Sydney Meshkov from CalTech)Next makeup class is Friday, Mar. 14,
1-2:30pm, rm 200.
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How is sin2qW measured?Cross section ratios between NC and CC
proportional to sin2qWLlewellyn Smith Formula:
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SM Global Fits with New ResultsWithout NuTeV c2/dof=20.5/14:
P=11.4%With NuTeV c2/dof=29.7/15: P=1.3%Confidence level in upper
Mhiggs limit weakens slightly.LEP EWWG:
http://www.cern.ch/LEPEWWG
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Tree-level Parameters: r0 and sin2qW(on-shell)Either
sin2qW(on-shell) or r0 could agree with SM but both agreeing
simultaneously is unlikely
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Model Independent AnalysisRn(`n) can be expressed in terms of
quark couplings:Where Paschos-Wolfenstein formula can be expressed
as
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Model Independent AnalysisDifficult to explain the disagreement
with SM by:Parton Distribution Function or LO vs NLO or Electroweak
Radiative Correction: large MHiggs
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Linking sin2qW with Higgs through Mtop vs MWOne-loop correction
to sin2qW
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Oscillation ProbabilitySubstituting the energies into the wave
function:Since the ns move at the speed of light, t=x/c, where x is
the distance to the source of nm.The probability for nm with energy
En oscillates to ne at the distance L from the source becomes
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Why is Neutrino Oscillation Important?Neutrinos are one of the
fundamental constituents in natureThree weak eigenstates based on
SMLeft handed particles and right handed anti-particles
onlyViolates parity Why only neutrinos?Is it because of its
masslessness?SM based on massless neutrinosMass eigenstates of
neutrinos makes flavors to mixSM in troubleMany experimental
results showing definitive evidences of neutrino oscillationSNO
giving 5 sigma results
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n Sources for Oscillation ExperimentsMust have some way of
knowing the fluxWhy?Natural SourcesSolar neutrinosAtmospheric
neutrinosManmade SourcesNuclear ReactorAccelerator
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Oscillation DetectorsThe most important factor is the energy of
neutrinos and its products from interactionsGood particle ID is
crucialDetectors using natural sourcesDeep under ground to minimize
cosmic ray backgroundUse Cerenkov light from secondary interactions
of neutrinosne + e e+X: electron gives out Cerenkov lightnm CC
interactions, resulting in muons with Cerenkov lightDetectors using
accelerator made neutrinosLook very much like normal neutrino
detectorsNeed to increase statistics
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Solar NeutrinosResult from nuclear fusion process in the
SunPrimary reactions and the neutrino energy from them are:
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Solar Neutrino Energy Spectrum
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Comparison of Theory and Experiments
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Sudbery Neutrino Observatory (SNO)Sudbery mine, Canada6800 ft
underground12 m diameter acrylic vessel1000 tons of D2O9600
PMTsElastic ScatteringNeutral Current
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SNO ne Event Display
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Solar Neutrino Flux
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SNO First Results
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Atmospheric NeutrinosNeutrinos resulting from the atmospheric
interactions of cosmic ray particlesnm to ne is about 2 to 1He, p,
etc + N p,K, etcp m+nmm e+ne+nmThis reaction gives 2 nm and 1
neExpected flux ratio between nm and ne is 2 to 1Form a double
ratio for the measurement
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Super KamiokandeKamioka zinc mine, Japan 1000m underground40 m
(d) x 40m(h) SS50,000 tons of ultra pure
H2O11200(inner)+1800(outer) 50cm PMTsOriginally for proton decay
experimentAccident in Nov. 2001, destroyed 7000 PMTsDec. 2002
resume data taking
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Atmospheric Neutrino Oscillations
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Super-K Atmospheric Neutrino Results
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Super-K Event Displays
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Other Experimental ResultsSoudan 2 experimentMacro
experiment
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Accelerator Based ExperimentsMostly nm from acceleratorsLong and
Short baseline experimentsLong 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
dispersionShort baseline: Detectors located at a close distance to
the sourceNeed to know flux well