Download presentation

Presentation is loading. Please wait.

Published byRosanna Ryan Modified over 2 years ago

1
TeV-scale seesaw with non-negligible left-right neutrino mixings Yukihiro Mimura (National Taiwan University) Based on arXiv:1110.2252 [hep-ph] Collaboration with N. Haba, T. Horita, and K. Kaneta (Osaka U) 1 Seminar at Academia Sinica (2012.1.13, Friday)

2
Introduction Neutrinos are massive, but active neutrino masses are tiny, < O(1) eV The simplest mechanism is type-I seesaw. “Natural” scale for

3
3 Q. Is there a chance to “observe” the right-handed neutrino? Ex. C.f. Right-handed neutrino mass can be O(100) GeV, but, …..

4
4 Left-right neutrino mixing: Ex. Negligibly small to create the Majorana neutrino at the collider.

5
5 Q. Is it possible to make the left-right mixing large enough to detect the existence of the right-handed neutrino? A. Yes, if generation structure is taken into account. Buchmuller-Wyler, Buchmuller-Greub, Tommasini-Barenboim-Bernabeu-Jarskog, Gluza, Kerstern-Smirnov, Adhikari-Raychaudhuri, Ma, He-Ma, He-Oh-Tandean-Wen, Chen-He-Tandean-Tsai, …. (sorry, incomplete list)

6
6 What we have done: 1.Find a convenient flavor basis to describe the non-negligible left-right neutrino mixing. 2.Consider a flavor symmetry to obtain a sizable left-right neutrino mixing. 3.Experimental implication

7
7 What we see in this talk: 1.Introduction (Done) 2.Convenient basis to describe the left-right neutrino mixing 3.Experimental constraints 4.Flavor symmetry 5.Experimental implications 6.Summary

8
8 = Diagonalization : PMSN neutrino mixing matrix :

9
9 Current eigenstate Mass eigenstates (approximate) active neutrino mixing matrix for neutrino oscillations Left-right neutrino mixing matrix

10
10 Lesson : Two-generation case Without loss of generality, we can choose (1,1) elements are zero by rotation of left- and right-handed fields.

11
11 In the limit b 0, the matrix is rank 2. Features of this basis: Easy to find a tiny active neutrino mass limit. Left-right mixing is characterized by

12
12 Multiplying from both sides,

13
13 After all, Diagonalization matrix of charged-lepton mass Diagonalization matrix of right-handed Majorana mass Note : precise experimental results require ~

14
14 Three-generation case Without loss of generality, we can choose a basis: In the limit b,d,e 0, the 6x6 neutrino matrix is rank 3. Features of this basis: Easy to find a tiny active neutrino mass limit. Left-right mixing is characterized by

15
15 After all, Ex. (T2K/MINOS/WCHOOZ/Daya Bay…) LHC (same-sign muons)

16
16 In old works in the literature, people works in the basis: is required for tiny neutrino mass. In our basis, The above condition is satisfied simply due to

17
17 Experimental constraints (Atre-Han-Pascoli-Zhang)

18
18 1.Colliders 2.Tau and K, D meson decays 3.Precision electroweak data 4.Neutrino-less double beta decay 5. Lepton flavor violation ~ (Fermi constant, lepton universality, invisible Z decay, …)

19
19 Numerical Example (Unit in GeV)

20
20 small Rank reduced Key structure : It can be realized by a flavor symmetry.

21
21 Froggatt-Nielsen mechanism U(1): SU(2):

22
22 Example: Dirac Yukawa : : B-L charged scalars which acquire VEV

23
23 (x denotes non-zero entry.) If both the Dirac and Majorana mass matrices are in the form : the seesaw mass matrix is also in the form of

24
24 Suppose that the mixings from the charged lepton are small, the Unitary matrix U is the MSN matrix. From the condition: we obtain …. Next page

25
25 (Only the case of Normal hierarchy gives solutions in the setup.) Using the experimental data, we obtain 13 mixing as a prediction. (Cubic equation of 13 mixing for given CP phase).

26
26 Current experimental best fit point :

27
27 Resonant production Same-sign WW fusion Same-sign di-lepton events at the LHC (This is more important)

28
28 Bare cross sections for same-sign di-muon (Atre-Han-Pascoli-Zhang) Datta-Guchait-Pilaftsis, Almeidia-Coutinho-Martins Simoes-do Vale, Panella-Cannoni-Carimalo-Srivastava, del Aguila-Aguilar-Saavedra, Chen-He-Tandean-Tsai, ….

29
29 LHC sensitivity (Atre-Han-Pascoli-Zhang)

30
30 Same-sign di-electron is strongly constrainted by double beta decay : Amplitude is proportional to. It can also controlled by a flavor symmetry. Same-sign di-electron can have a chance to be observed.

31
31 Several special cases: Two-lighter right-handed neutrino masses are degenerate. Double beta decay vanishes. Double beta decay and μ e γ vanish. Two right-handed neutrino masses are degenerate. Lepton number(-like) symmetry remains. Degeneracy of Majorana neutrino Merit of TeV-scale resonant leptogenesis 1 2 3

32
32 Summary 1.We consider a convenient basis to describe the non-negligible left-right neutrino mixing. 2.Tiny neutrino masses can be realized even if the left-right mixing is sizable. 3.The neutrino mass structure can be controlled by a flavor symmetry. 4.Same-sign di-electron events may be observed as well as di-muon events, satisfying the constraint of neutrino-less double beta decay.

Similar presentations

Presentation is loading. Please wait....

OK

Universality of weak interactions?

Universality of weak interactions?

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on 3g mobile technology download Ppt on australian continental divide Ppt on law against child marriage in yemen File type ppt on cybercrime virus Ppt on history of atom Ppt on revolution of the earth and seasons kids Ppt on polynomials of 91 Ppt on solid dielectrics glass Ppt on area of plane figures Ppt on bluetooth architecture piconets