B. Dutta

Texas A&M University

Phys.Rev.Lett.99:261301, 2007; To appear

Inflation, Dark Matter and Neutrino Masses

Collaborators: Rouzbeh Allahverdi, Anupam Mazumdar

ICHEP ‘08

Inflation and Dark Matter: Needs new physics

What is this well motivated model particle physicsmodel?

Neutrino masses are small and require new physics: Can they be tied to this model?

How can we test this model? Where?

LHC, dark matter detection …

How economically can we achieve all these?

Introduction

We consider supersymmetry

Dark Matter Candidate ~ (weak scale)

Inflaton Mass ~ (weak scale)

Sneutrino (spin 0) is the candidate

Scalar Inflaton field contains the DM particleSneutrino

Left Sneutrinos are ruled out as dark matter candidates

We will consider New Sneutrinos

Supersymmetry Framework

We consider simple extension: SU(3) x SU(2)L x U(1)Y x U(1)B-L

B-L sneutrino can be the dark matter candidate

U(1)B-L gets broken at a TeV or so

We have an extra Z’ and 3 more neutralinos

This is a minimal extension of the SM

Model

The model provides Dirac mass for neutrinos

The inflaton is composed of : Higgs field, Slepton and Sneutrino

The corresponding flat direction : NHuL (W h NHuL)

The mass of the flat direction is described in terms of the sparticle masses O(weak scale)

The mass of the inflaton, ~ O(weak scale)

Inflaton

Note: DM candidate sneutrino is a part of the inflaton

3

~~LHN u

where,

Flat direction and MSSM [Allahverdi, Enqvist, Kusenko, Mazumdar…]

The potential along the flat direction :

h is the Yukawa coupling

For A = 4 m

We get V’(0)=0 V’’(0)=0 but V’’’(0) 0

342

22

||36

||12

||2

|)(| AhhmV f

V()=V(0)+1/3!V’’’(0)(-0)3+…

Potential for inflation

V

In order to fit the CMBR result we need h~10-12

We need this small coupling to explain the neutrino mass

We have Dirac neutrinos

=h<Hu> M~O(0.1) eV

Tiny neutrino mass arises when we explain inflation in this model

Small Neutrino Mass

Inflaton is related to the neutrino mass:

H ~ 1.91 x 10-5

Amplitude of Perturbations: H ~ f(m,m,0)

Inflaton vs neutrino masses

Phys.Rev.Lett.99:261301, 2007

Inflaton and sparticle masses are correlated

We use SUGRA boundary condition

=1200 GeVmg~

1640 GeV

730 GeV

m=0.3 eV

Each line: Left end m0=0; Right end : M(sneutrino)=M(neutralino)

Inflaton and other SUSY masses

Dark matter content is explained: Sneutrino is the LSP

Sneutrino component of inflaton has never decayed

-prime: t –channel, Z-prime: s-channelZ~

Dark Matter Content

Phys.Rev.Lett.99:261301, 2007

Direct Detection of dark matter

LHC: Signal is similar as in the standard scenario with neutralino LSP

If we can identify the spin of dark matter particleit is possible extract this model

Work in progress…

N~ interacts with quark via Z’ exchange

Typical cross section : 2 x10-8 pb for Z’ mass ~ 2 TeV

Collider Signal:

Signal

However, sneutrino has spin 0

Conclusion

It is possible to explain Inflation and dark matter in the context of particle physics model

We need to extend the MSSM by an extra U(1) symmetry

Sneutrino is the dark matter candidate which is part of the flat direction for inflation

Dark Matter content can be satisfied

Direct detection experiment can observe it

One can distinguish this scenario at the LHC if the spin of the missing particle can be measured