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.

How is sin2qW measured?Cross section ratios between NC and CC proportional to sin2qWLlewellyn Smith Formula:

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

Tree-level Parameters: r0 and sin2qW(on-shell)Either sin2qW(on-shell) or r0 could agree with SM but both agreeing simultaneously is unlikely

Model Independent AnalysisRn(`n) can be expressed in terms of quark couplings:Where Paschos-Wolfenstein formula can be expressed as

Model Independent AnalysisDifficult to explain the disagreement with SM by:Parton Distribution Function or LO vs NLO or Electroweak Radiative Correction: large MHiggs

Linking sin2qW with Higgs through Mtop vs MWOne-loop correction to sin2qW

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

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

n Sources for Oscillation ExperimentsMust have some way of knowing the fluxWhy?Natural SourcesSolar neutrinosAtmospheric neutrinosManmade SourcesNuclear ReactorAccelerator

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

Solar NeutrinosResult from nuclear fusion process in the SunPrimary reactions and the neutrino energy from them are:

Solar Neutrino Energy Spectrum

Comparison of Theory and Experiments

Sudbery Neutrino Observatory (SNO)Sudbery mine, Canada6800 ft underground12 m diameter acrylic vessel1000 tons of D2O9600 PMTsElastic ScatteringNeutral Current

SNO ne Event Display

Solar Neutrino Flux

SNO First Results

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

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

Atmospheric Neutrino Oscillations

Super-K Atmospheric Neutrino Results

Super-K Event Displays

Other Experimental ResultsSoudan 2 experimentMacro experiment

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