Low scale supergravity mediation Low scale supergravity mediation in brane world scenario and in brane world scenario and hidden sector phenomenology hidden sector phenomenology

Phys.Rev.D74:055005,2006（ arXiv: hep-ph/0606156 ）

ACFA07 in Beijing: 2007.2.5

Hideo Itoh (KEK)in collaboration with

Nobuchika Okada (KEK) and Toshifumi Yamashita (SISSA)

1.Introductio1.IntroductionnStandard Model We have fine-tuning prob.

SM vacuum is not stable under quantum correctionssince Higgs self energy is UV sensitive:

Supersymmetry A possibility to solve above prob.

New physics without quadratic div. in quantum corrections

Minimal Supersymmetric SM (MSSM)

Minimal supersymmetric extension of the Standard Model

But…

Sparticles have not been observed yet

SUSY must be broken at low energy

MSSM

We introduce soft breaking terms to break SUSY by hand

SUSY should be spontaneously broken

What is the origin of SUSY breaking?

SUSY is broken by hidden sector

X : super field of hidden sectorFX: F-term of hidden sector

SUSY breaking is caused by F-term of hidden sector

Basic scenario

Simplest hidden sector model

Next we consider SUSY breaking mediation

Image of SUSY breaking mediation

Hidden sector MSSM sectorgravitygauge anomalygaugino… at Λ which is a mediation scale

Mediated by

SUSY breaking effect is mediated at mediation scale Λ

・ gauge mediation

・ gravity mediation (mSUGRA)Ex.)

Sfermion mass:

Gaugino mass:

Sparticle mass

Our work

We propose a new scenario of the low scale SUGRA mediation

・ Brane world scenario in warped extra dimensions・ Mediation scale becomes low:Λ ～ 1–10TeV 　　　　　　　　 　　　　　・ Interesting collider phenomena as will be shown

2.New low scale SUSY breaking model 2.New low scale SUSY breaking model

Λ0>0 Λπ<0

Extra-dim

ΛBulk<0

We conpactified 5th dim. as S1/Z2 orbifolding

Solution of Einstein eq.

・ r : radius of 5th dim.・ y : angle of S1

・ k : curvature of bulk

Brane setup in warped extra dimensions(Randall-Sundrum setup)

UV brane IR braneExtra-dim

On the IR brane

In effective 4-dim. theory

Cutoff on the IR brane (ΛIR) is effectively “warped down”

Warp factor

In this setup, SUSY breaking mediation is the same as mSUGRA on the IR brane.

Our new field setup on branes

V

H

gravity

IR braneUV brane

Both of the hidden and visible sectors on the same IR brane

Warp factor is a free parameter of our model　 → ΛIR is a free parameter!

Sparticle masses on this set up

Generate from higher dimensional operators

Suppressed by effective mass scale ΛIR= ω MPl not by 4D Planck scale!

4D mSUGRA case

Interaction between hidden and visible sectors

If ΛIR << MPl Contact int. between hidden andvisible sectors become strong!

In the following, we investigate hidden sector pheno.

3.Hidden sector 3.Hidden sector phenomenologyphenomenology

If the hidden sector scalar X is light enough (MX < 1TeV), it can be produced at LHC and ILC!

ILCLHC

Production processes are similar to Higgs productions

If ΛIR is order TeV scale Can produce hidden sectorat collider experiments

But, the decay processes are quite different as will be discussed in the following

・ Higgs production ・ X-production

At LHC

・ mX ～ mh ～ 120GeV・ ΛIR ～ 10TeV

X to SM fermion pair coupling

Partial decay width into light fermion pairs is very much suppressed

This feature is quite different in comparison with Higgs case.

X to gauge boson pair coupling

Decay processes

(c,c1,c2 and c3 are order one parameters)

Br

Mh[GeV]

Branching ratio

gg

γγ WW

ZZtt

bb

Br

MX[GeV] 1000

1

10-1

10-2

10-3

100 200

X decays h decays

103

102

101

100

10-1

Event number ratio

5 10 100

Event number ratio is very much enhanced up to ΛIR ～ 100TeV.So we may probe hidden sector to use this signal at LHC.

Mh=MX=120GeV

Higgs production

Angular distributionis quite different asyou will see next.

At ILC

X production

X production

Higgs production

Angular distribution

Longitudinal modedominates

Higgs case X case

Transverse modedominates

6

8

4

0 1-1 0.2 0.4 0.6 0.8-0.2-0.4-0.6-0.8

2

0

[fb]

Angular distribution

Other interesting process

No SM background!We are doing simulation studiesH. Itoh, K. Fujii, N. Okada & T. Yoshioka,

　　 work in progress 　

4.Summary4.Summary

We have proposed a new setup of the mSUGRA in warped extra dimensions.

・ Visible and hidden sectors on the same IR brane・ Cutoff scale can be low

Enhanced contact interactions between hidden and visible

fields

Cutoff scale is low

The hidden sector field may be produced at LHC or ILC!

Production cross sections become comparable with Higgs case

Br(X→γγ) is enhanced event number very much in comparison with h→γγ.This signal is large and clean at LHC!!

Cutoff scale ~ TeV

Decay processes are quite different

We may detect hidden sector at LHC and ILC!

But

Production processes are similar to Higgs

Back up slide

Another interesting feature

In our model

c1,c2,c3 = 1

Gaugino masses relation Decay width of X to VV

induce

Every original mass scale is warped down on the IR brane.

4. 4. ΛIR ～ 10TeV is natural

Ex.)

In the RS brane setup, it is natural that ΛIR ～ 10TeV.

From a view point of naturalness, everything looks like going well…

at LHC

We may probe the hidden sector.

(Suppose mild hierarchy)

・・ Backup slideBackup slideGravitino mass

4D effective theory → should reproduce 4D gravity correctly

Gravitino becomes LSP by warping down