Yang-Hwan, Ahn (KIAS) - PDF Free Download

Yang-Hwan, Ahn (KIAS) Collaboration with Paolo Gondolo (Univ. of Utah) Appear to 1312.xxxxx 2013 Particle Theory Group @ Yonsei Univ. 1

The SM as an effective theory Several theoretical arguments (inclusion of gravity, instability of he Higgs potential, neutrino masses,.) and cosmological evidence (dark matter, inflation, cosmological constant, ) point toward the existence of physics beyond the SM. The outstanding puzzles in the SM are enormously various hierarchies spanned by the fermion masses and their mixing patterns : 2

Questions Why lepton mixing angles are so different from those of the quark sector? The bi-large mixing angles of leptons may be telling us about some new symmetries not presented in the quark sector and provide a clue to the nature of the quark-lepton physics beyond the SM. Why neutrino masses are so small, compared with the charged fermion masses? The huge smallness of neutrino masses compared to the charged fermion masses is related to the existence of a new fundamental scale, and thus new physics beyond the SM. [SEESAW Mechanism] Why the hierarchy of neutrino masses are so mild, while those of charged fermion masses are so strong? The large ratios between the masses of fermions of successive generations may be due to higher order effects. [Froggatt-Nielsen Mechanism] 3

What determines the observed pattern of masses and mixings of quarks and leptons? Our Idea No clear direction for future searches large number of independent (1) parameters In a complete model, the mass scale suppression can be identified as the masses of the messenger fields 4

A new advanced approach for the flavor puzzle It consists of the introduction of family symmetries with higher order effects, which constrains the flavor structure of Yukawa couplings and lead to predictions for fermion masses and mixings : The gauge singlet flavon field is activated to dimension-4(3) operators with different orders Non-Abelian flavor symmetry + anomalous U(1) global symmetry are imposed The coefficients are all of order one is the scale of flavor dynamics, and is a mass scale for the FN fields which are integrated out 5

Present Knowledges on Quark and Lepton sectors 6

Present Knowledges on Quark and Lepton sectors 7

Present Knowledges on Quark and Lepton sectors 8

Present Knowledges on Quark and Lepton sectors 9

SEESAW A simple and attractive explanation of the smallness ofνmass Bulit-in mechanism for generating BAU so-called Leptogenesis 3 3 Seesaw model Integrating out the heavy states 18 parameters ( 12 real+6 pha 9 observables ( 6 real+3 phases ) Half of the parameters of the model get lost at low-e The 3 low-e CP-violating phases depend, in general, on all 6 seesaw phases. 10

Present Knowledges on Quark and Lepton sectors 11

lepton sector All data can be explained in terms of oscillation between just 3 known species Their neutrino species have definite masses : Two possible orderings of neutrino masses Earth matter effects(lbl) Quasi-Degenerate case And one lepton flavor can convert to another 12

U PMNS Pontecorvo-Maki-NaKagawa-Sakata (PMNS) Matrix 1 0 0 c 0 s e c s 0 i CP 13 13 12 12 0 c23 s23 0 1 0 s12 c12 0 i CP 0 s23 c 23 s13e 0 c 13 0 0 1 Atmospheric and SBL reactor Solar and LBL accelerator LBL reactor P Not observable in Neutrino oscillation Majorana phases Neutrinoless Double beta decay 13

Where Do we Stand? (arxiv: 1209, 3023 Gonzalez-Garcia, Maltoni, Salvado and Schwetz) Large mixings (solar & Atm) New flavor symmetry 14

Where Do we Stand? (arxiv: 1209, 3023 Gonzalez-Garcia, Maltoni, Salvado and Schwetz) Large mixings (solar & Atm) New flavor symmetry Relatively large 13 can give constraint CP (LBL experiments T2K and No A) 15

Where Do we Stand? 18

Where Do we Stand? There are empirical fermion mass hierarchies in the charged leptons, up- and down-type quark sectors calculated from the measured values (PDG) m u :m c :m t =λ 8 :λ 4 :1 m d :m s :m b =λ 4 :λ 2 :1 m e :m μ :m τ =λ 5 :λ 2 :1 Quark mixing angles 19

Flavor Symmetry In approaches to reconstruct the high-energy physics from low-energy data, one can assume a flavor symmetry, which may reduce the unknown parameters Unless flavor symmetries are assumed, particle masses and mixings are generally undetermined in gauge theory: A4, T, S4, S3 : Discrete & Non-Abelian global spontaneously broken at high-energy broken by a set of scalar fields which transform only under the flavor sym. Symmetry Breaking 20

A4 Symmetry (Smallest group for three-families) Even permutations of 4 objects : S 2 =T 3 =(ST) 3 =I S 2 =I Z2 symmetry T 3 =I Z3 symmetry Finite group of S, TST 2, T 2 ST 12 elements in 4 T, TS, ST, STS conjugacy classes T 2, ST 2, T 2 S, TST 1 There are 4 irreducible representation : 1, 1, 1, 3 Why A4 (Discrete & non-abelian)? 3 2 A4 is the smallest discrete group that has 3-dimensional irreducible representation A4 flavor symmetry can give a µ- symmetric pattern for experimental data subgroup itself large mixings mismatch between Z2 and Z3 symmetry 4 21

The Model 23

Fermionic tetrahedral Symmetry A 4 24

Fermionic tetrahedral Symmetry A 4 Comparison with Ma, Rajasekaran (2001), Babu, Ma, Valle (2003) Ahn, Gondolo See also, Ahn, Baek, Gondolo (2012) Ma, Rajasekaran (2001) Babu, Ma, Valle (2003) 25

Leptonic tetrahedral Symmetry A 4 Minimal Yukawa couplings!! Each Dirac-like and charged-lepton sector has three independent Yukawa terms A non-degenerate Dirac-neutrino Yukawa matrix Heavy s acquire mass terms induced by and fields The three leptons e, µ, are eigenstates of T with eigenvalues 1,, 2 respectively : L e (e R ) 1 L µ (µ R ) L ( R ) 2 As a consequence, the charged lepton mass matrix automatically diagonal. 26

Quark tetrahedral Symmetry A 4 Each flavor of up-(down-)type quarks has three independent Yukawa terms; the down-type terms involve the A4 triplets and D R, and singlets Q L, while the up-type terms involve the A4 singlet and singlets Q L. The right-handed up-type quarks are eigenstates of T with eigenvalues 1, 2, respectively : =exp(2 i/3) u R 1, c R, t R 2 27

U(1) X Hierarchy : Strong & Mild 28

U(1) X Hierarchy : Strong & Mild 29

U(1) X Hierarchy : Strong & Mild 30

U(1) X Hierarchy : Strong & Mild Provide off-diagonal entries in the matrix and lead to the correct CKM 31

Spontaneously-broken Leptonic A 4 Symmetry 5 parameters : y 1 32

Spontaneously-broken Leptonic A 4 Symmetry 33

After seesawing In the limit y 2 y 3 the above matrix goes to µ- symmetry leading to θ 13 =0 and θ 23 =45 In the limit y 2 =y 3 1 TBM: θ 13 =0, θ 23 =45 and θ 12 =sin -1 (1/ 3) Non-zero 13 requires deviations of y 2, y 3 from unit, in turn implying a possibility of Leptonic CP violation 34

Phenomenology of light neutrino Model prediction, CP-violating phases and 0 -decay 35

Neutrinoless double beta decay NMO : IMO : 36

Leptonic Dirac CP-phase vs Atm. angle NMO : + IMO : NMO favors 23 >45 and 23 <45 (but small deviations from the maximality), while IMO favors 23 <45 and 23 >45 with large deviations from maximality. 37

0 -decay m ee vs Atm. mixing 23 NMO : + IMO : Our model can be tested in the very near future neutrino oscillation experiments and/or 0 -decay experiments 38

0 -decay m ee vs Atm. mixing 23 NMO : + IMO : 39

0 -decay m ee vs Atm. mixing 23 NMO : + IMO : 40

Conclusion 41

The Higgs sector We have to make terms sufficiently small, which would destroy the vacuum stability One example: use extra dimensions 42