Flavor Symmetry Models

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Flavor Symmetry Models

• Hitoshi Murayama (UC Berkeley)
• 2nd Intl Scoping Study Meeting
• KEK, January 23, 2006

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How do we understand this?
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Question of Flavor

• What distinguishes different generations?
• Same gauge quantum numbers, yet different
• Hierarchy with small mixings
• ? Need some ordered structure
• Probably a hidden flavor quantum number
• ? Need flavor symmetry
• Flavor symmetry must allow top Yukawa
• Other Yukawas forbidden
• Small symmetry breaking generates small Yukawas
• Repeat Gell-Mann Okubo!

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Broken Flavor Symmetry

• Flavor quantum numbers (SU(5)-like)
• 10(Q, uR, eR) (2, 1, 0)
• 5(L, dR) (1, 1, 1)
• Flavor symmetry broken by a VEV ???0.02
• mumcmt md2ms2mb2 me2mm2mt2 ?4 ?2 1

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Not bad!

• mb 3mt, ms 3mm, md 3me
• mumcmt md2ms2mb2 me2mm2mt2

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New Insight from Neutrinos

• Neutrinos are already providing significant new
  information about flavor symmetries
• If LMA, all mixing except Ue3 large
• Two mass splittings not very different
• Atmospheric mixing maximal
• Any new symmetry or structure behind it?

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Is There a Structurein Neutrino Masses Mixings?

• Monte Carlo random complex 3?3 matrices with
  seesaw mechanism
• (Hall, HM, Weiner Haba, HM)

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Anarchy

• Reasonable distributions from randomness
• ? Underlying symmetries dont distinguish 3
  neutrinos.
• Flavor quantum numbers
• 10(Q, uR, eR) (2, 1, 0)
• 5(L, dR) (1, 1, 1)
• Inconceivable just a few years ago

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q13 in Anarchy

• q13 cannot be too small if anarchy
• How often can large angle fluctuate down to the
  CHOOZ limit?
• KolmogorovSmirnov test 12
• sin2 2q13gt0.004 (3s)
• CP violation very likely observable at long
  baseline experiment

(de Gouvêa, HM)
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Anarchy is Peaceful

• Anarchy (Miriam-Webster)
• A utopian society of individuals who enjoy
  complete freedom without government
• Peaceful ideology that neutrinos work together
  based on their good will
• Predicts large mixings, LMA, large CP violation
• sin22q13 just below the bound
• Ideal for superbeam, n-factory
• ? Pro-globalization!

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Different Flavor Symmetries

• Altarelli-Feruglio-Masina hep-ph/0210342

Hall, HM, Weiner
Sato, Yanagida Vissani
Barbieri et al
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Critical Measurements

• sin2 2q231.00?0.01?
• Determines a need for a new symmetry to enforce
  the maximal mixing
• sin2 2q13lt0.01?
• Determines if the flavor quantum number of
  electron is different from mu, tau
• Normal or inverted hierarchy?
• Most symmetries predict the normal hierarchy
• CP Violation?
• Plausibility test of leptogenesis

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Large q23 and quarks

• Large mixing between nt and nm
• Make it SU(5) GUT
• Then a large mixing between sR and bR
• Mixing among right-handed fields drop out from
  CKM matrix
• But mixing among superpartners physical
• O(1) effects on b?s transition possible
• (Chang, Masiero, HM)
• Expect CP violation in neutrino sector especially
  if leptogenesis
• Bs?J/y f?? Bd?f Ks

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More FossilsLepton Flavor Violation

• Neutrino oscillation
• ? lepton family number is not conserved!
• Any tests using charged leptons?
• Top quark unified with leptons
• Slepton masses split in up- or neutrino-basis
• Causes lepton-flavor violation (Barbieri, Hall)
• predict B(t?mg), B(m?eg), m?e at interesting (or
  too-large) levels

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Dynamics behind flavor symmetry?

• Once flavor symmetry structure identified (e.g.,
  Gell-ManOkubo), what is dynamics? (e.g., QCD)

• Supersymmetry
• Anomalous U(1) gauge symmetry with Green-Schwarz
  mechanism
• Large Extra Dimensions
• Fat brane with physically separated left- and
  right-handed particles
• Technicolor
• New broken gauge symmetries at 100TeV scale

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Conclusions

• Revolutions in neutrino physics
• The solar neutrino problem solved!
• Small but finite neutrino mass
• Probes physics beyond the standard model
• New insights into the origin of flavor
• Interesting interplay between neutrinos and
  cosmos
• Neutrino mass may be responsible for our
  existence
• Neutrinos may even be the origin of the universe
• A lot more to learn in the next few years