NEUTRINOS: PAST PRESENT FUTURE Heidi Schellman @ Frank Merritt Fest 2015 1

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NEUTRINOS:PAST PRESENT FUTUREHeidi Schellman @ Frank Merritt Fest 2015

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What we knew in 1971

Neutrinos exist (Cowan, Reines 1956) There are two kinds (Lederman,

Schwartz, Steinberger - 1962 ) They may interact through W and Z

boson exchange (Glashow, Weinberg, Salaam - 1968)

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FERMILAB NALCAL, July 1971 NAL, CALTECH JOIN IN NEUTRINO

STUDIES (EXPERIMENT 21) The Caltech-NAL researchers planned

to carry their studies on neutrinos up to about 300 BeV. In July 1971, data existed only up to about 10 BeV.

Evidence suggests the W has a mass greater than that of two protons…

The Caltech-NAL experiment …, hoped to produce and detect the particle if its mass is less than about 20 proton masses.

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Neutral currents observed 1973

Gargamelle hadronic neutral current event

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Weinberg angle measurement: 1997

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What we know now

Neutrinos Oscillate! Solar – Davis 1960’s Atmospheric – SuperK – 1998 + many others

Neutrinos have Mass (but what is it?) The mixing angles are largish!

q13 - Daya Bay, RENO, Chooz, T2K, MINOS - 2012

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Precision measurements

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11 What’s left

Unknown: Mass hierarchy and mass offset

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NormalHierarchy

InvertedHierarchy

Dm12

Dm23 > 0

Dm23 < 0

We know the absolute value of the mass differences but not the minimum mass or the sign of Dm2

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??Interactions with matter can tell the difference.Dm2

12 > 0 is known from solar, sign of Dm2

23 is still unknown

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By 2035: Mass Hierarchy and CP violating phase – DUNE + HyperK + reactor

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Absolute mass scale may take longer!

Dm213 = .0025 says at least 1 has m >

0.050 eV Cosmology - Sm < 0.23 eV - PLANCK

2015 Direct - me < 0.200 eV – Katrin 2018? Neutrino-less 2b decay

If Majorana And inverted hierarchy

Stolen from MR-M at NSAC Workshop

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Surprises

Is there CP violation in the Majorana phases?

Are there more ‘sterile’ neutrino species? Are there right handed ones? Are they the dark matter?

Why don’t we know what 95% of the Universe is anyways?

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Example: nMSM

3 “light” R-handed neutrinos, keV and GeV mass scales

N1 is dark matter candidate

N2 N3 may be visible in CCFR/NuTeV ATLAS/CMS Beam dump

experiments

Phys.Rev.Lett. 110 (2013) 6, 061801

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Neutrinos tell no lies

Neutrinos are hard to make They are hard to find But once you find them, every one tells

you a lot