Proton Decay at DUSEL

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Proton Decay at DUSEL
Stuart Raby

DUSEL Town Meeting Washington, D.C. November 3,
2007
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Motivation for Deep Underground Science
Laboratory

• Long-baseline neutrino oscillations
• q13 , leptonic CP viol.
• Astrophysical neutrinos - SN, solar,
  neutrino bkgd.
• Neutrino masses - neutrinoless 2b decay
• Direct dark matter detection
• n-nbar oscillations
• Proton decay
• Can all be done with one large detector
• Conclusions

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Outline

• SUSY GUTs
• motivation and consequences
• Proton decay
• Conclusions

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Supersymmetric Standard Model
Motivation ??
Solve hierarchy problem MZ/MPl 10-16
SM - fine-tuning 10-32
SUSY
technically natural
Dynamical
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Phenomenology of SUSY GUTs

• charge quantization

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Pati-Salam SU(4)CxSU(2)LxSU(2)R
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Georgi-Glashow
Pati-Salam
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Charge quantization
Georgi Fritzsch Minkowski
spinor repsn. of SO( 10 )
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Phenomenology

• charge quantization
• gauge coupling unification

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Gauge coupling unification
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Phenomenology

• charge quantization
• gauge coupling unification
• neutrino masses
• See-Saw scale ( .01 - .1 ) MGUT

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Phenomenology

• charge quantization
• gauge coupling unification
• neutrino masses
• LSP- dark matter candidate
• baryogenesis via leptogenesis
• quark and lepton masses

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Fermion Masses in SO(10)
l 16 10 16
top, bottom, tau, nt Yukawa unification
Minimal SO(10) Model
Mohapatra, Babu, Senjanovic, Bajc, Aulakh, Chen,
Mahanthappa,
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Minimal SO(10) Model
II
Albright, Anderson, Babu, Barr, Barbieri,
Berezhiani, Blazek, Carena, Dermisek,
Dimopoulos, Hall, Pati, Raby, Romanino, Rossi,
Starkman, Wagner, Wilczek, Wiesenfeldt,
Willenbrock
Possible UV completion to strings !!
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SO(10) x D3 x U(1) family sym. Yukawa
Unification for 3rd Family
Dermisek Raby hep-ph/0507045 Dermisek,
Harada S.R. hep-ph/0606055
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SO(10) x D3 x U(1) family sym. Yukawa
Unification for 3rd Family
Fits fermion masses and mixing angles well
Requires soft SUSY breaking paras
Blazek, Dermisek Raby PRL 88 (2002)
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Global c2 analysis of DR Model
24 parameters at GUT scale
compare to SM - 27 parameters
MSSM - 32 parameters
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Recent analysis of DR Model
Challenging SO(10) SUSY GUTs with
family symmetries through FCNC processes Albrecht
, Altmannshofer, Buras, Guadagnoli, Straub
arXiv0707.3954 hep-ph

Find good fits to quark, charged lepton
neutrino masses and mixing angles Also test
flavor violation in b physics some tension
between b ? s g b ? s l l-
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UV completion
Orbifold GUTs in 5 or 6 dimensions GUT
symmetry breaking Doublet-Triplet splitting
Kawamura Hall Nomura Contino, Pilo, Rattazzi
Trincherini Altarelli, Feruglio Masina
Dermisek Mafi H.D. Kim Raby Asaka,
Buchmuller Covi Lee Hebecker March-Russell
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M4 x S1/(Z2xZ2)

P
P
P P parity affect boundary conditions at
fixed points
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E6 Orbifold GUT on M4 x S1/(Z2xZ2)
Kobayashi, SR Zhang
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UV completion
Orbifold GUTs in 5 or 6 dimensions Derived
from Heterotic string in 10 D
Kobayashi, Raby Zhang Forste, Nilles,
Vaudrevange Wingerter Buchmuller,
Hamaguchi, Lebedev Ratz JE Kim, JH Kim
Kyae Buchmuller, Ludeling Schmidt
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E8 x E8 Heterotic string in 10D
Compactify 6D on (T2)3
Then mod by Z6 (Z3 x Z2) and Add Wilson
lines
Z6 embedded in E8 x E8 gauge lattice as shift
V6 consistent with mod. inv. !
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First consider (T2)3/Z3 W3
Wilson line in
SU3 torus
Massless modes From Untwisted sector
(G2 , SU3) twisted sector
E6 GUT in 5D
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Recently obtained MSSM
from heterotic string With 3 families, no
light exotics and non-trivial
quark lepton masses Lebedev et
al. The Heterotic Road to the MSSM with R
parity,''
arXiv0708.2691 hep-th
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Phenomenology

• charge quantization
• gauge coupling unification
• neutrino masses
• dark matter candidate
• baryogenesis via leptogenesis
• quark and lepton masses
• proton decay

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Proton Decay -- gauge exchange
Lucas Raby, Murayama Pierce
MX gt 7x 1015 GeV tp gt 1.5x1034
years
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Proton Decay -- higgs exchange
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Proton Decay -- higgs exchange

• c color triplet Yukawa coupling --
• In a complete GUT its constrained by
• fermion masses and mixing angles
• blattice - a 0.0118(21) GeV3
• ß 0.0118(21) GeV3
• Y. Aoki
  et al. hep-lat/0607002

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Proton Decay -- higgs exchange

• Loop factor
• gauginos (light), 12 gen. scalars
  (heavy)
• constrained by gauge coupling
• unification and GUT breaking sectors

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Proton Decay -- higgs exchange
Babu, Pati Wilczek, Altarelli, Feruglio
Masina, Dermisek, Mafi Raby
SUSY GUTs Under siege !!
Dermisek, Mafi Raby
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Proton Decay Orbifold GUTs

• 5 6 dimensionful orbifold GUTs
• dim. 5 operators - can be suppressed
• dim. 6 operators - typically
  enhanced
• MX lt MGUT
• String orbifolds
• dim. 5 operators strike back
• dim. 6 operators - likely enhanced

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Conclusions

• SUSY GUTs predict proton neutron
• decay with lifetimes exceeding BUT near
• Super-K bounds
• 5D Orbifold GUTs can suppress dim. 5
• BUT enhance dim. 6 operators
• Strings may enhance both ?
• Observation of proton decay would
• dramatically change our understanding of
• nature !!

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Conclusions
Proton decay should be just around the
corner BUT which mode dominates ? The
answer is model dependent !!
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Conclusions
Proton decay should be just around the
corner BUT which mode dominates ? The
answer is model dependent !!