Beyond the MSSM

From the little hierarchy problem to the Baryon Asymmetry of the Universe

Kfir Blum

Advisors:

Yossi Nir and Eli Waxman

Supersymmetry (SUSY) is a great idea

It fixes the fine tuning problem

MSSM = simplest SUSY extension of SM Higgs sector extremely predictive:

more so than in SM!

…But it does not completely solve the tuning – little hierarchy problem remains

The little hierarchy problem

MSSM: at classical level, mH< mZ=91 GeV ! LEPII: mH>114 GeV

need large quantum corrections; can do with very heavy stops, mst>TeV

This implies % tuning

If additional DOF heavy M >> mZ, general way to proceed is via effective field theory:

Beyond MSSM

MSSM ain’t the whole story(we know this: for one, it isn’t enough to break SUSY)

Can additional DOF solve little hierarchy problem?

BMSSM

• Expand in powers of m/M, m ~ mZ << M

• Higgs sector:

)Approx’( SUSY + leading m/M Only two operators !

• In the scalar potential:

For M < 10 TeV,

More than enough to lift mH above LEP at classical level

See e.g. Dine, Seiberg & Thomas,

Phys.Rev.D76:095004,2007

BMSSM: Implications for vacuum stability and Cosmology

• Vacuum stability

• Dark Matter

• The electroweak phase transition and electroweak baryogenesis

Blum, Delaunay & Hochberg,

Phys.Rev.D80:075004,2009

Bernal, Blum, Losada & Nir ,

JHEP 0908:053,2009

Blum, Delaunay, Losada, Nir, Tulin,Work in progress

Bernal, Blum, Losada & Nir ,

JHEP 0908:053,2009 Blum & Nir ,

Phys.Rev.D78:035005,2009

MSSM

BMSSM

BMSSM Higgs potential non trivial.

Raise mH tunneling problem ?

Vacuum stability

…SUSY implies:

Constraints remain:

• Must not overcome gauge couplings• Upper bound on M

MSSM

BMSSM

Baryon Asymmetry of the Universe cannot be solved within SM

MSSM EWBG – little hierarchy amplified

need mH~114 GeV, but also light stop

other stop very heavy big little hierarchy

BMSSM:• Can have 2 light stops! No hierarchy• New couplings CP violation• Spontaneous EWBG

BMSSM

Electroweak Baryogenesis

Summary

* MSSM little hierarchy problem – due to constrained Higgs sector, solved Beyond-MSSM * Vacuum stability – SUSY renders effective theory simple & consistent

* Implications for Cosmology

– Natural EW Baryogenesis with 2 light stops – DM scenarios )bulk region reopens(

Outlook

* Spontaneous EW Baryogenesis

* Light stop phenomenology

* Microscopic realizations

Thanks!

Xtras

If…

•BMSSM respects R-parity

•Approximately SUSY (msoft<<M)

SUSY breaking via spurions

Pure Higgs:

Only 2 new operators!…enough to solve little hierarchy problem

Choice of basis

Leading mass shift

Dimension 6 scalar term,

and condition for neglecting it

2-loop thermal corrections associated with dim 6 term

Effective potential

EWPT I

EWPT – Barrier Formation

• First order: barrier forms between EW breaking and conserving minima

• Barrier height depends on light scalar dof coupling to the higgs field, and on thermal screening

• In SM, only gauge bosons contribute to barrier

• In MSSM, negative soft squared-mass can reduce thermal screening for stops, making them the dominant player by far

BMSSM higgsinos

Chargino-chargino-scalar-scalar

terms and modifications to the mass

matrices exist as well

Most natural parameter spacefor MSSM DM:Bino annihilates via lightsfermion exchange.

Example – mSUGRA Bulk Region.

If sfermion spectrum correlated )light sleptons light stops(,LEPII kills bulk region, since stopsmust be heavy.

BMSSM Dark Matter

BMSSM:

• mH decoupled from mst

efficient sfermion t-channel,

bulk region lives• Stop co-annihilation region

Also:

• Higgs resonance channel,

• Modified Higgsino couplings