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Hiroaki SUGIYAMA(Ritsumeikan Univ., Shiga, Japan)

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Introduction
Neutrino masses are extremely smaller than other fermion masses.

Neutrino-specific mechanism to generate their masses ?

Yukawa with SM Higgs?

Yukawa with new scalar ?

Seesaw with very heavy particle ?

Light new scalar ?

Far from experimental reach

LHC ?

3/27

Large Hadron Collider

first event of Higgs
at ATLAS (4 Apr. 2008)

first event of Higgs
at CMS (4 Apr. 2008)

collider at(cf. Tevatron:

at26.7km ring (cf. 26.4km loop subway in Nagoya, Japan)

ATLAS: Higgs , new phys.
ALICE: quark-gluon plasma

CMS: Higgs , new phys.
LHCb: B phys.

TOTEM (near CMS): elastic and diffractive cross sections
LHCf (near ATLAS): cosmic ray)

4/27

New scalars at the LHC

Leptophilic Scalars !
Origin of neutrino masses

5/27

Yukawa Interactions with Leptophilic Scalars
singlet: Singly charged (e.g., in Zee model): Doubly charged (e.g., in Zee-Babu model)
Radiative neutrino mass

doublet: Neutrinophilic doublet
Tree neutrino mass

triplet(e,g., in Higgs Triplet Model)

6/27

ModelYukawa interactions

LHC
Scalar decay into leptons

Goal (Hope)

Origin of neutrino mass
Neutrino mass matrix

T2K, DCHOOZ, Daya Bay, RENO, …
Neutrino oscillation data

7/27

Doubly Charged ScalarDoubly Charged Higgs - Triplet Target :Symmetric

Higgs Triplet Model

W. Konetschny and W. Kumer, PLB70, 433 (1977)
M. Magg and C. Wetterich, PLB94, 61 (1980)
T.P. Cheng and L.F. Li, PRD22, 2860 (1980)
J. Schechter and J.W.F. Valle, PRD22, 2227 (1980)

Yukawa :Neutrino masses :Scalar potential :Soft breaking of8/27

9/27

Set upTarget :10/27

Information on

A.G. Akeroyd, M. Aoki, HS, PRD 77,075010

See also J. Garayoa, T. Schwetz, JHEP 0803,009
M. Kadastki, M. Raidal, L. Rebane, PRD 77, 115023

11/27

Information on Non-Zerothe lightest mass

12/27

Information on CP-Violation with Majorana Phases13/27

Doubly Charged Scalar - Singlet Target :Symmetric

Zee-Babu Model

A. Zee, NPB264, 99 (1986)
K.S. Babu, PLB203, 132 (1988)

Yukawa :Mass eigenstate
Neutrino masses :14/27

orNo

contribution (assumption)K.S. Babu and C. Macesanu, PRD67, 073010 (2003)
D. Aristizabal Sierra and M. Hirsch, JHEP0612, 052 (2006)
M. Nebot et al., PRD77, 093013 (2008)

15/27Singly Charged Scalar16/27Singly Charged Higgs - Doublet or Triplet Neutrinophillic Doublet

S. Gabriel and S. Nandi, PLB655, 141 (2007)
S.M. Davidson and H.E. Logan, PRD80, 905008 (2009)

Only for neutrinos
Neutrino Yukawa ::odd

Dirac neutrinos :( Spontaneous Symmetry Breaking
Scalar potential :)Soft breaking ofSet up for Dirac neutrinos

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Target :Set up for Majorana neutrinos (“HTM-like” case)Target :(See also, S. Kanemura and K. Yagyu, arXiv:1201.6287 )18/27

S.M. Davidson and H.E. Logan, PRD80, 905008 (2009)19/27

P. Fileviez Perez et al., PRD78, 015018 (2008)

20/27Singly Charged Scalar - Singlet 1 Mass eigenstate (assumption)

Target :AntisymmetricSimplest Zee Model

A. Zee, PLB93, 389 (1980)
L. Wolfenstein, NPB175, 93 (1980)

Doublet Yukawa :No Flavor-Changing-Neutral-Current

Excluded by Oscillation datae.g., X.G. He, EPJC34, 371 (2004)

General (Original) Zee Model

A. Zee, PLB93, 389 (1980)

Doublet Yukawa :Incl. FCNC
Set upMass eigenstate (assumption)

Target :Antisymmetric

Neutrino mass :dominance (assumption)

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22/27orNot acceptable: Arbitlary

23/27Singly Charged Scalar - Singlet 2 Set up
Mass eigenstate (assumption)

Target :Antisymmetric

Majorana neutrinos :Example : Zee-Babu model

A. Zee, NPB264, 99 (1986)
K.S. Babu, PLB203, 132 (1988)

Dirac neutrinos :Example : 1-loop model

S. Nasri and S. Moussa, MPLA17, 771 (2002)
S. Kanemura, T. Nabeshima, HS, PLB703, 66 (2011)24/27or

K.S. Babu and C. Macesanu, PRD67, 073010 (2003)
D. Aristizabal Sierra and M. Hirsch, JHEP0612, 052 (2006)
M. Nebot et al., PRD77, 093013 (2008)
S. Kanemura, T. Nabeshima, HS, PLB703, 66 (2011)25/27or

K.S. Babu and C. Macesanu, PRD67, 073010 (2003)
D. Aristizabal Sierra and M. Hirsch, JHEP0612, 052 (2006)
M. Nebot et al., PRD77, 093013 (2008)
S. Kanemura, T. Nabeshima, HS, PLB703, 66 (2011)26/27

Summary of My Hope - 1
triplet :Doubly charged :Singly charged :or not ?

or not ?
or not ?

oror not ?

doublet :27/27

Summary of My Hope - 2
singly charged

singlet :or(Majorana)

doubly charged

singlet :Zee-Babu model ??

(Dirac)