B. Dutta

Texas A&M University

Phys.Rev.Lett.100:181801,2008; arXiv:0805.2988; To appear

Grand Unified Models, Proton Decay and Phase of

Collaborator: Yukihiro Mimura

ICHEP 08

Large FCNCs exist for general SUSY breaking masses.

Flavor universality of SUSY breaking is assumed to solve the flavor problem.

FCNCs can still be induced by RGEs.

In MSSM, the quark FCNCs are small due to small CKM mixings.

If there is a heavy particle, e.g., heavy right handed neutrino, the loop corrections can induce sizable FCNCs due to large neutrino mixing. (Borzumati-Masiero)

Flavor Violation in Grand Unified Models

The flavor violation effects teach us GUT scale physics

Introduction

and are correlated.

In this talk :

In GUT models,

(Belle)

The phase of . Is also restricted

We will study large CP phase in SU(5) and SO(10) GUT models.

The nature of FCNC and CP violation is very important to test the existence of new physics

FCNC and New Physics

Dutta, Mimura, Phys.Rev.Lett.97:241802,2006.

Large Phase of

CP violation in

Measurements :

SM prediction : small!

2.2 sigma deviation from the SM

(arXiv: 0712.2397)

(arXiv: 0802.2255)

Combined data analysis by UTfit: More than 3 sigma deviation from the SM

arXiv:0803.0659

The gluino box diagram dominates.

Mass insertion approximation:

b s

s b

(Ball-Khalil-Kou)

However, experimental result of does not constrain size of SUSY contribution much.

Accurate measurement of mass difference is consistent with SM.

There is room for a sizable SUSY contribution.

One may think that large SUSY contribution is not allowed.

New Physics Contribution in the Mixing

Due to free phases in the Yukawa coupling

[Tevatron]

What is this large SUSY contribution?

SU(5) GUT

Down quarks and lepton doublet are unified in

Right-handed neutrino :

Both RH down-squarks and LH sleptons can have FCNC effects.

(Moroi, Akama-Kiyo-Komine-Moroi, Baek-Goto-Okada-Okumura, …)

U is the MNS neutrino mixing matrix.

SU(5) GUT…

The flavor violating elements in m25 induces Bs mixing

Sparticle spectrum is restricted. LHC

SU(5) GUT…

2

1

in Bs mixing

Stau coannihilation region

Higgsino dark matter region

Both left- and right-squarks have FCNC effects in SO(10).

Flavor violating effects are larger in the box diagram in SO(10).

SO(10) GUT

In the SO(10) model, can be large due to left-right box enhancement.

can be suppressed by a choice of vacua.

If (8,2,1/2) (in 126 Higgs) is light, it generates FCNC in the quark sector

For example,

Light (8,2,1/2) is needed to suppress proton decay.

(Dutta-Mimura-Mohapatra, Phys.Rev.Lett.100:181801,2008. )

SO(10) GUT…

(8,2,1/2) introduces flavor violation only in the squark sector

If is suppressed by a choice of the vacua, constraint is important.

However, can be adjusted to be the experimental rangeunless is enhanced too much by gluino contribution.

(this requires small left-right mixing for sbottom)

Direct CP violation of can be largefor large

Large Tan

h0, H0, A0

bR sL

bRsL

Double penguin diagram can have largeContribution

This diagram’s contribution (~tan4/MA4)

Similar single penguin diagrams contribute to Bs process (~2tan6/MA

4)

Large Bs phase induces larger Bs process even for tan~20 for universal boundary condition

Both SU(5) and SO(10) get contribution from this diagram

Chargino and gluino mediated penguins contribute

Conclusion We study the bound of from the LFV in SUSY GUT models.

SUSY spectrum is restricted in SU(5) modelwhere Dirac neutrino is the origin of the large phase.

SO(10) models can generate larger phases.

We expect further accurate experimentsto learn more about the GUT scale physics from the

Back up slides

(95%)

(UTfit)